William J. Brady, MD

The use of bolus-dose vasopressors in anesthesiology and other areas of critical care medicine is well known. This common medical intervention, however, is not often employed in emergency medicine (EM). Bolus-dose vasopressors are defined as the administration of small bolus doses of vasopressor agents, such as epinephrine or phenylephrine, to patients with compromised perfusion who continue to have a pulse (ie, these patients are not in cardiac arrest). This intervention is considered as a temporizing measure for transient hypotension or as a bridge to more definitive therapy.

Clinical Application

Bolus-dose vasopressive therapy is also referred to as push-dose pressor (PDP) therapy—a term coined by Weingart.^1-3 Theoretically, any vasopressor could be used in a mini-dose, bolus fashion, though in current clinical practice, anesthesiologists primarily employ ephedrine, epinephrine, and phenylephrine. Two of these agents are likely more appropriate for the ED, including epinephrine and phenylephrine. Both of these agents have a short half-life and therefore an abbreviated period of effect. In addition, dosing and related administration of epinephrine and phenylephrine is relatively straightforward. Moreover, most emergency physicians and nurses are quite familiar with both agents.

With respect to ephedrine, due to its longer half-life, complex dosing regimen, and associated higher-incidence of cardiovascular (CV) complications, its use is likely not appropriate in the ED as a bolus-dose vasopressor.

Epinephrine and Phenylephrine

Epinephrine is a potent sympathomimetic agent with alpha- and beta-receptor activity. In addition to its vasopressor effects, epinephrine is also an inotropic and chronotropic agent, increasing cardiac output, heart rate (HR), and systemic vascular resistance, which can markedly improve perfusion. Epinephrine also can be given to patients with hypoperfusion and/or shock due to low-cardiac output with or without vasodilation, lacking significant tachycardia.

Phenylephrine is a pure alpha agonist and therefore does not appreciably affect cardiac output and HR, but does significantly increase systemic vascular resistance and thus systemic perfusion. Phenylephrine can be used to treat patients with hypoperfusion and/or shock states due to vasodilation with coexistent, significant tachycardia.

Preparation and Administration

The preparation and dosing of push-dose epinephrine and phenylephrine are not particularly complex. Many clinicians recommend the pre-mixed, manufacturer-prepared agents for PDP therapy. These premixed formulations not only facilitate administration, but also reduce the chance of a preparation error that can result in incorrect dosing.^3-5 If pre-mixed formulations are not available, clinicians can readily prepare epinephrine and phenylephrine for PDP use.

Push-Dose Epinephrine. Clinicians can prepare epinephrine for push-dose administration as follows:^1-3

• Obtain 1 mL of epinephrine 1:10,000 (ie, 0.1 mg/mL or 100 mcg/mL);
• Obtain a 10 mL syringe of normal saline and remove 1 mL;
• Inject the 1 mL of epinephrine 1:10,000 (100 mcg/mL) into this syringe containing 9 mL of normal saline; and
• Result: 10 mL of epinephrine (10 mcg/mL), with each 1 mL of this solution containing 10 mcg of epinephrine.

Administration of push-dose epinephrine (10 mcg/mL) produces effect within 1 minute of use with a duration of approximately 5 to 10 minutes. Dosing at this concentration ranges from 0.5 to 2.0 mL every 2 to 5 minutes, delivering 5 to 20 mcg.^1-3Push-Dose Phenylephrine. To prepare phenylephrine for push-dose administration, clinicians may use the following approach:^1-3

• Obtain 1 mL of phenylephrine (10 mg/mL concentration);
• Inject this 1 mL of phenylephrine (10 mg/mL) into a 100 mL bag of normal saline; and
• Result: 100 mL of phenylephrine (100 mcg/mL), with each 1 mL of this solution containing 100 mcg of phenylephrine.

Administration of push-dose phenylephrine (100 mcg/mL) produces effect within 1 minute of use with a duration of approximately 10 to 20 minutes. Dosing at this concentration ranges from 0.5 to 2.0 mL every 2 to 5 minutes, delivering 50 to 200 mcg.^1-3Alternative Push-Dose Preparations for Phenylephrine. Two other methods of preparing phenylephrine for bolus-dose administration include the following: (1) the addition of phenylephrine 20 mg to a bag of 250 cc of normal saline, resulting in an 80 mcg/mL concentration; and/or (2) phenylephrine (20 mg) is commercially available for continuous infusion in a 250 mL bag of normal saline, yielding the same concentration of 80 mcg/mL; in either case, medication can be drawn up and administered. Dosing at this concentration ranges from 0.5 to 2.5 mL every 2 to 5 minutes, delivering 40 to 200 mcg. Lastly, phenylephrine is also commercially available in pre-made mixtures, specifically manufactured for bolus-dose therapy.

Indications

Both epinephrine and phenylephrine can be considered in the management of significant transient or sustained hypoperfusion. Although the definition of significant hypotension is complex, Brunauer et al⁶ have suggested that a mean arterial pressure (MAP) of approximately 35 mm Hg is associated with a significant risk of CV collapse. Of course, a MAP of 40 to 50 mm Hg is also very concerning clinically, with significant risk of deterioration and CV collapse.

Procedural events, such as conscious sedation or rapid sequence intubation (RSI), can produce significant hypotension; PDP can rapidly correct hypotension. In other clinical scenarios in which sustained hypotension is likely and not transient (eg, sepsis with shock), PDP can be used as a bridge to definitive care (eg, volume replacement, continuous vasopressor infusion). It is important to note, however, that PDP administration must occur in conjunction with or after the patient has received other appropriate therapies such as a normal saline bolus and continuous vasopressor infusions. Push-dose pressors are not a replacement for these proven interventions, but rather are an important augmentation to these therapies.

Emergency Medicine Literature

As previously noted, the literature base describing and supporting the clinical use of PDP in EM is extremely limited. The few articles that comprise this literature base address significant hypotension in periendotracheal intubation intervention, post-return of spontaneous circulation (ROSC) management, and shock management with preload augmentation.^7-9In addition, there are several articles in the literature that address safety concerns surrounding the use of PDP in the ED.^4,5

Panchal et al¹⁰ investigated the use of phenylephrine in hypotensive patients undergoing RSI-assisted endotracheal intubation. The authors performed a 1-year retrospective review of hypotensive patients managed with endotracheal intubation for a range of clinical conditions that required clinical care intervention. In this study, 20 of the 119 patients received phenylephrine in the peri-intubation period. A range of clinical conditions requiring critical care intervention were encountered; in addition, almost three-quarters of these patients were receiving at least one other vasopressor infusion. Further differences were seen in the timing of PDP administration. In those patients receiving bolus-dose phenylephrine, blood pressure (BP) improved without change in HR. Panchal et al¹⁰ concluded that while push-dose phenylephrine improved hemodynamic status, there was significant variation among clinicians regarding dosing, timing of use, and overall clinical situation The significant variation in PDP management in this study was noted to be a potential source of medical error, thus increasing the chance of adverse clinical event.

Push-dose pressor therapy can be employed for significant hypotension while more definitive therapy is being readied and applied. For instance, patients with significant hypotension requiring continuous vasopressor infusion can be managed with PDP while appropriate venous access is established, intravenous fluids are administered, and medications are prepared. The immediate period after resuscitation from cardiac arrest can be complicated by shock of many types. In fact, hypotension following ROSC in the cardiac arrest patient is not uncommon and has been identified as a risk issue associated with poor outcome. Prompt treatment of this altered perfusion may improve outcome. Gottlieb⁸ described three patients with ROSC after cardiac arrest. All three patients experienced significant, sustained hypotension with systolic blood pressure reading in the 50 to 60 mm Hg range; bolus-dose epinephrine was administered with significant improvement in the hemodynamic status while central venous access was established.

In a related clinical scenario, Schwartz et al⁹ considered the impact of PDP on central venous line (CVL) placement with continuous vasopressor infusion. In this ED study, although patients experienced an increase in BP, this impact was transient with approximately half of these individuals ultimately requiring CVL. In addition, serious adverse effect was noted more commonly in the phenylephrine-treated patients with “reactive” hypertension and ventricular tachycardia occurring in study patients.

Patient-Safety Considerations

In addition to the limited literature base supporting PDP use in the ED, another major significant issue focuses on safety concerns and adverse effects. Extremely limited data is available describing adverse events related to ED-administered PDP. Extrapolating from other EM and critical care administrations of peripheral epinephrine, both local and systemic adverse effects have been reported.^11,12 The range of adverse events noted in these studies are considerable, including local skin and soft-tissue injury (necrosis), end-organ tissue ischemia (eg, digits, tip of nose), acute hypertension, cardiac ischemic events, and left ventricular (LV) dysfunction.^11,12

When comparing peripheral infusion with central infusion, the risk of extravasation with resultant local tissue injury is markedly greater with peripheral vasopressor administration. In a systematic review of this issue, Loubani and Green¹¹ noted that such local adverse events were much more commonly associated with peripheral administration.

In another report of vasopressor use in the ED, Kanwar et al¹² described apparent confusion with epinephrine dosing and route of administration, resulting in very significant, systemic CV maladies, including severe elevations in BP, acute LV dysfunction, and chest pain associated with ST segment elevation.

It must be stressed that the publications by Loubani and Green¹¹ and Kanwar et al¹² described peripheral vasopressor administration: neither study included PDP therapy. Therefore, as previously noted, the aforementioned statements are extrapolated from when applied to PDP strategy.

Acquisto et al⁴ describe several errors in medication administration of PDP in the ED and other critical care areas of the hospital. In this report, all treating physicians were present at the patients’ bedside, either administering the medication or directly supervising its use. Agents involved included epinephrine and phenylephrine, delivered at exceedingly high doses. In their study, the authors noted several issues which they believe contributed to medication errors, including heterogeneity of pathology treated in these patients, apparent “earlier-than-appropriate” use of vasopressors (ie, prior to giving an appropriate fluid bolus), and medication preparation at the bedside by clinicians who may not possess the experience and training to mix these agents.

From a patient-safety perspective, Holden et al⁵ noted the potential for dosing error with significant adverse medical consequence related to PDP, as well as several contributing issues. First, they highlight the lack of a solid literature base to support administration of PDP in the ED and the development of decision-making guidelines for use in the ED. They also observed an inconsistency in approach to patient selection, medication choice, agent preparation, dosing, and other therapies. As seen in the Acquisto et al⁴ report, the patient-care scenarios are high risk and quite dynamic.

Conclusion

Bolus-dose vasopressor therapy is a potentially very useful treatment in the ED and other emergency/critical care settings. However, despite its benefits in treating patients in shock or with hypoperfusion, PDP is not widely used in EM due to the lack of studies, reviews, and guidelines in the literature to support its use in the ED. Such a literature base is required to provide an appropriate, safe means of patient selection, medication choice, dosing, and administration. Continued educational and research efforts are needed to more fully explore the use of PDP therapy in the ED.

When used correctly and appropriately, PDP has promise to be an important aid in the management of shock in the ED. Although bolus-dose therapy is appropriate for select clinical scenarios involving significant shock states which have the potential for progression to complete CV collapse without timely therapy, it is an adjunct to, not a replacement for commonly employed and medically indicated therapies such as crystalloid bolus or continuous vasopressor infusions.

The use of bolus-dose vasopressors in anesthesiology and other areas of critical care medicine is well known. This common medical intervention, however, is not often employed in emergency medicine (EM). Bolus-dose vasopressors are defined as the administration of small bolus doses of vasopressor agents, such as epinephrine or phenylephrine, to patients with compromised perfusion who continue to have a pulse (ie, these patients are not in cardiac arrest). This intervention is considered as a temporizing measure for transient hypotension or as a bridge to more definitive therapy.

Clinical Application

Bolus-dose vasopressive therapy is also referred to as push-dose pressor (PDP) therapy—a term coined by Weingart.^1-3 Theoretically, any vasopressor could be used in a mini-dose, bolus fashion, though in current clinical practice, anesthesiologists primarily employ ephedrine, epinephrine, and phenylephrine. Two of these agents are likely more appropriate for the ED, including epinephrine and phenylephrine. Both of these agents have a short half-life and therefore an abbreviated period of effect. In addition, dosing and related administration of epinephrine and phenylephrine is relatively straightforward. Moreover, most emergency physicians and nurses are quite familiar with both agents.

With respect to ephedrine, due to its longer half-life, complex dosing regimen, and associated higher-incidence of cardiovascular (CV) complications, its use is likely not appropriate in the ED as a bolus-dose vasopressor.

Epinephrine and Phenylephrine

Epinephrine is a potent sympathomimetic agent with alpha- and beta-receptor activity. In addition to its vasopressor effects, epinephrine is also an inotropic and chronotropic agent, increasing cardiac output, heart rate (HR), and systemic vascular resistance, which can markedly improve perfusion. Epinephrine also can be given to patients with hypoperfusion and/or shock due to low-cardiac output with or without vasodilation, lacking significant tachycardia.

Phenylephrine is a pure alpha agonist and therefore does not appreciably affect cardiac output and HR, but does significantly increase systemic vascular resistance and thus systemic perfusion. Phenylephrine can be used to treat patients with hypoperfusion and/or shock states due to vasodilation with coexistent, significant tachycardia.

Preparation and Administration

The preparation and dosing of push-dose epinephrine and phenylephrine are not particularly complex. Many clinicians recommend the pre-mixed, manufacturer-prepared agents for PDP therapy. These premixed formulations not only facilitate administration, but also reduce the chance of a preparation error that can result in incorrect dosing.^3-5 If pre-mixed formulations are not available, clinicians can readily prepare epinephrine and phenylephrine for PDP use.

Push-Dose Epinephrine. Clinicians can prepare epinephrine for push-dose administration as follows:^1-3

• Obtain 1 mL of epinephrine 1:10,000 (ie, 0.1 mg/mL or 100 mcg/mL);
• Obtain a 10 mL syringe of normal saline and remove 1 mL;
• Inject the 1 mL of epinephrine 1:10,000 (100 mcg/mL) into this syringe containing 9 mL of normal saline; and
• Result: 10 mL of epinephrine (10 mcg/mL), with each 1 mL of this solution containing 10 mcg of epinephrine.

Administration of push-dose epinephrine (10 mcg/mL) produces effect within 1 minute of use with a duration of approximately 5 to 10 minutes. Dosing at this concentration ranges from 0.5 to 2.0 mL every 2 to 5 minutes, delivering 5 to 20 mcg.^1-3Push-Dose Phenylephrine. To prepare phenylephrine for push-dose administration, clinicians may use the following approach:^1-3

• Obtain 1 mL of phenylephrine (10 mg/mL concentration);
• Inject this 1 mL of phenylephrine (10 mg/mL) into a 100 mL bag of normal saline; and
• Result: 100 mL of phenylephrine (100 mcg/mL), with each 1 mL of this solution containing 100 mcg of phenylephrine.

Administration of push-dose phenylephrine (100 mcg/mL) produces effect within 1 minute of use with a duration of approximately 10 to 20 minutes. Dosing at this concentration ranges from 0.5 to 2.0 mL every 2 to 5 minutes, delivering 50 to 200 mcg.^1-3Alternative Push-Dose Preparations for Phenylephrine. Two other methods of preparing phenylephrine for bolus-dose administration include the following: (1) the addition of phenylephrine 20 mg to a bag of 250 cc of normal saline, resulting in an 80 mcg/mL concentration; and/or (2) phenylephrine (20 mg) is commercially available for continuous infusion in a 250 mL bag of normal saline, yielding the same concentration of 80 mcg/mL; in either case, medication can be drawn up and administered. Dosing at this concentration ranges from 0.5 to 2.5 mL every 2 to 5 minutes, delivering 40 to 200 mcg. Lastly, phenylephrine is also commercially available in pre-made mixtures, specifically manufactured for bolus-dose therapy.

Indications

Both epinephrine and phenylephrine can be considered in the management of significant transient or sustained hypoperfusion. Although the definition of significant hypotension is complex, Brunauer et al⁶ have suggested that a mean arterial pressure (MAP) of approximately 35 mm Hg is associated with a significant risk of CV collapse. Of course, a MAP of 40 to 50 mm Hg is also very concerning clinically, with significant risk of deterioration and CV collapse.

Procedural events, such as conscious sedation or rapid sequence intubation (RSI), can produce significant hypotension; PDP can rapidly correct hypotension. In other clinical scenarios in which sustained hypotension is likely and not transient (eg, sepsis with shock), PDP can be used as a bridge to definitive care (eg, volume replacement, continuous vasopressor infusion). It is important to note, however, that PDP administration must occur in conjunction with or after the patient has received other appropriate therapies such as a normal saline bolus and continuous vasopressor infusions. Push-dose pressors are not a replacement for these proven interventions, but rather are an important augmentation to these therapies.

Emergency Medicine Literature

As previously noted, the literature base describing and supporting the clinical use of PDP in EM is extremely limited. The few articles that comprise this literature base address significant hypotension in periendotracheal intubation intervention, post-return of spontaneous circulation (ROSC) management, and shock management with preload augmentation.^7-9In addition, there are several articles in the literature that address safety concerns surrounding the use of PDP in the ED.^4,5

Panchal et al¹⁰ investigated the use of phenylephrine in hypotensive patients undergoing RSI-assisted endotracheal intubation. The authors performed a 1-year retrospective review of hypotensive patients managed with endotracheal intubation for a range of clinical conditions that required clinical care intervention. In this study, 20 of the 119 patients received phenylephrine in the peri-intubation period. A range of clinical conditions requiring critical care intervention were encountered; in addition, almost three-quarters of these patients were receiving at least one other vasopressor infusion. Further differences were seen in the timing of PDP administration. In those patients receiving bolus-dose phenylephrine, blood pressure (BP) improved without change in HR. Panchal et al¹⁰ concluded that while push-dose phenylephrine improved hemodynamic status, there was significant variation among clinicians regarding dosing, timing of use, and overall clinical situation The significant variation in PDP management in this study was noted to be a potential source of medical error, thus increasing the chance of adverse clinical event.

Push-dose pressor therapy can be employed for significant hypotension while more definitive therapy is being readied and applied. For instance, patients with significant hypotension requiring continuous vasopressor infusion can be managed with PDP while appropriate venous access is established, intravenous fluids are administered, and medications are prepared. The immediate period after resuscitation from cardiac arrest can be complicated by shock of many types. In fact, hypotension following ROSC in the cardiac arrest patient is not uncommon and has been identified as a risk issue associated with poor outcome. Prompt treatment of this altered perfusion may improve outcome. Gottlieb⁸ described three patients with ROSC after cardiac arrest. All three patients experienced significant, sustained hypotension with systolic blood pressure reading in the 50 to 60 mm Hg range; bolus-dose epinephrine was administered with significant improvement in the hemodynamic status while central venous access was established.

In a related clinical scenario, Schwartz et al⁹ considered the impact of PDP on central venous line (CVL) placement with continuous vasopressor infusion. In this ED study, although patients experienced an increase in BP, this impact was transient with approximately half of these individuals ultimately requiring CVL. In addition, serious adverse effect was noted more commonly in the phenylephrine-treated patients with “reactive” hypertension and ventricular tachycardia occurring in study patients.

Patient-Safety Considerations

In addition to the limited literature base supporting PDP use in the ED, another major significant issue focuses on safety concerns and adverse effects. Extremely limited data is available describing adverse events related to ED-administered PDP. Extrapolating from other EM and critical care administrations of peripheral epinephrine, both local and systemic adverse effects have been reported.^11,12 The range of adverse events noted in these studies are considerable, including local skin and soft-tissue injury (necrosis), end-organ tissue ischemia (eg, digits, tip of nose), acute hypertension, cardiac ischemic events, and left ventricular (LV) dysfunction.^11,12

When comparing peripheral infusion with central infusion, the risk of extravasation with resultant local tissue injury is markedly greater with peripheral vasopressor administration. In a systematic review of this issue, Loubani and Green¹¹ noted that such local adverse events were much more commonly associated with peripheral administration.

In another report of vasopressor use in the ED, Kanwar et al¹² described apparent confusion with epinephrine dosing and route of administration, resulting in very significant, systemic CV maladies, including severe elevations in BP, acute LV dysfunction, and chest pain associated with ST segment elevation.

It must be stressed that the publications by Loubani and Green¹¹ and Kanwar et al¹² described peripheral vasopressor administration: neither study included PDP therapy. Therefore, as previously noted, the aforementioned statements are extrapolated from when applied to PDP strategy.

Acquisto et al⁴ describe several errors in medication administration of PDP in the ED and other critical care areas of the hospital. In this report, all treating physicians were present at the patients’ bedside, either administering the medication or directly supervising its use. Agents involved included epinephrine and phenylephrine, delivered at exceedingly high doses. In their study, the authors noted several issues which they believe contributed to medication errors, including heterogeneity of pathology treated in these patients, apparent “earlier-than-appropriate” use of vasopressors (ie, prior to giving an appropriate fluid bolus), and medication preparation at the bedside by clinicians who may not possess the experience and training to mix these agents.

From a patient-safety perspective, Holden et al⁵ noted the potential for dosing error with significant adverse medical consequence related to PDP, as well as several contributing issues. First, they highlight the lack of a solid literature base to support administration of PDP in the ED and the development of decision-making guidelines for use in the ED. They also observed an inconsistency in approach to patient selection, medication choice, agent preparation, dosing, and other therapies. As seen in the Acquisto et al⁴ report, the patient-care scenarios are high risk and quite dynamic.

Conclusion

Bolus-dose vasopressor therapy is a potentially very useful treatment in the ED and other emergency/critical care settings. However, despite its benefits in treating patients in shock or with hypoperfusion, PDP is not widely used in EM due to the lack of studies, reviews, and guidelines in the literature to support its use in the ED. Such a literature base is required to provide an appropriate, safe means of patient selection, medication choice, dosing, and administration. Continued educational and research efforts are needed to more fully explore the use of PDP therapy in the ED.

When used correctly and appropriately, PDP has promise to be an important aid in the management of shock in the ED. Although bolus-dose therapy is appropriate for select clinical scenarios involving significant shock states which have the potential for progression to complete CV collapse without timely therapy, it is an adjunct to, not a replacement for commonly employed and medically indicated therapies such as crystalloid bolus or continuous vasopressor infusions.

The use of bolus-dose vasopressors in anesthesiology and other areas of critical care medicine is well known. This common medical intervention, however, is not often employed in emergency medicine (EM). Bolus-dose vasopressors are defined as the administration of small bolus doses of vasopressor agents, such as epinephrine or phenylephrine, to patients with compromised perfusion who continue to have a pulse (ie, these patients are not in cardiac arrest). This intervention is considered as a temporizing measure for transient hypotension or as a bridge to more definitive therapy.

Clinical Application

Bolus-dose vasopressive therapy is also referred to as push-dose pressor (PDP) therapy—a term coined by Weingart.^1-3 Theoretically, any vasopressor could be used in a mini-dose, bolus fashion, though in current clinical practice, anesthesiologists primarily employ ephedrine, epinephrine, and phenylephrine. Two of these agents are likely more appropriate for the ED, including epinephrine and phenylephrine. Both of these agents have a short half-life and therefore an abbreviated period of effect. In addition, dosing and related administration of epinephrine and phenylephrine is relatively straightforward. Moreover, most emergency physicians and nurses are quite familiar with both agents.

With respect to ephedrine, due to its longer half-life, complex dosing regimen, and associated higher-incidence of cardiovascular (CV) complications, its use is likely not appropriate in the ED as a bolus-dose vasopressor.

Epinephrine and Phenylephrine

Epinephrine is a potent sympathomimetic agent with alpha- and beta-receptor activity. In addition to its vasopressor effects, epinephrine is also an inotropic and chronotropic agent, increasing cardiac output, heart rate (HR), and systemic vascular resistance, which can markedly improve perfusion. Epinephrine also can be given to patients with hypoperfusion and/or shock due to low-cardiac output with or without vasodilation, lacking significant tachycardia.

Phenylephrine is a pure alpha agonist and therefore does not appreciably affect cardiac output and HR, but does significantly increase systemic vascular resistance and thus systemic perfusion. Phenylephrine can be used to treat patients with hypoperfusion and/or shock states due to vasodilation with coexistent, significant tachycardia.

Preparation and Administration

The preparation and dosing of push-dose epinephrine and phenylephrine are not particularly complex. Many clinicians recommend the pre-mixed, manufacturer-prepared agents for PDP therapy. These premixed formulations not only facilitate administration, but also reduce the chance of a preparation error that can result in incorrect dosing.^3-5 If pre-mixed formulations are not available, clinicians can readily prepare epinephrine and phenylephrine for PDP use.

Push-Dose Epinephrine. Clinicians can prepare epinephrine for push-dose administration as follows:^1-3

• Obtain 1 mL of epinephrine 1:10,000 (ie, 0.1 mg/mL or 100 mcg/mL);
• Obtain a 10 mL syringe of normal saline and remove 1 mL;
• Inject the 1 mL of epinephrine 1:10,000 (100 mcg/mL) into this syringe containing 9 mL of normal saline; and
• Result: 10 mL of epinephrine (10 mcg/mL), with each 1 mL of this solution containing 10 mcg of epinephrine.

Administration of push-dose epinephrine (10 mcg/mL) produces effect within 1 minute of use with a duration of approximately 5 to 10 minutes. Dosing at this concentration ranges from 0.5 to 2.0 mL every 2 to 5 minutes, delivering 5 to 20 mcg.^1-3Push-Dose Phenylephrine. To prepare phenylephrine for push-dose administration, clinicians may use the following approach:^1-3

• Obtain 1 mL of phenylephrine (10 mg/mL concentration);
• Inject this 1 mL of phenylephrine (10 mg/mL) into a 100 mL bag of normal saline; and
• Result: 100 mL of phenylephrine (100 mcg/mL), with each 1 mL of this solution containing 100 mcg of phenylephrine.

Administration of push-dose phenylephrine (100 mcg/mL) produces effect within 1 minute of use with a duration of approximately 10 to 20 minutes. Dosing at this concentration ranges from 0.5 to 2.0 mL every 2 to 5 minutes, delivering 50 to 200 mcg.^1-3Alternative Push-Dose Preparations for Phenylephrine. Two other methods of preparing phenylephrine for bolus-dose administration include the following: (1) the addition of phenylephrine 20 mg to a bag of 250 cc of normal saline, resulting in an 80 mcg/mL concentration; and/or (2) phenylephrine (20 mg) is commercially available for continuous infusion in a 250 mL bag of normal saline, yielding the same concentration of 80 mcg/mL; in either case, medication can be drawn up and administered. Dosing at this concentration ranges from 0.5 to 2.5 mL every 2 to 5 minutes, delivering 40 to 200 mcg. Lastly, phenylephrine is also commercially available in pre-made mixtures, specifically manufactured for bolus-dose therapy.

Indications

Both epinephrine and phenylephrine can be considered in the management of significant transient or sustained hypoperfusion. Although the definition of significant hypotension is complex, Brunauer et al⁶ have suggested that a mean arterial pressure (MAP) of approximately 35 mm Hg is associated with a significant risk of CV collapse. Of course, a MAP of 40 to 50 mm Hg is also very concerning clinically, with significant risk of deterioration and CV collapse.

Procedural events, such as conscious sedation or rapid sequence intubation (RSI), can produce significant hypotension; PDP can rapidly correct hypotension. In other clinical scenarios in which sustained hypotension is likely and not transient (eg, sepsis with shock), PDP can be used as a bridge to definitive care (eg, volume replacement, continuous vasopressor infusion). It is important to note, however, that PDP administration must occur in conjunction with or after the patient has received other appropriate therapies such as a normal saline bolus and continuous vasopressor infusions. Push-dose pressors are not a replacement for these proven interventions, but rather are an important augmentation to these therapies.

Emergency Medicine Literature

As previously noted, the literature base describing and supporting the clinical use of PDP in EM is extremely limited. The few articles that comprise this literature base address significant hypotension in periendotracheal intubation intervention, post-return of spontaneous circulation (ROSC) management, and shock management with preload augmentation.^7-9In addition, there are several articles in the literature that address safety concerns surrounding the use of PDP in the ED.^4,5

Panchal et al¹⁰ investigated the use of phenylephrine in hypotensive patients undergoing RSI-assisted endotracheal intubation. The authors performed a 1-year retrospective review of hypotensive patients managed with endotracheal intubation for a range of clinical conditions that required clinical care intervention. In this study, 20 of the 119 patients received phenylephrine in the peri-intubation period. A range of clinical conditions requiring critical care intervention were encountered; in addition, almost three-quarters of these patients were receiving at least one other vasopressor infusion. Further differences were seen in the timing of PDP administration. In those patients receiving bolus-dose phenylephrine, blood pressure (BP) improved without change in HR. Panchal et al¹⁰ concluded that while push-dose phenylephrine improved hemodynamic status, there was significant variation among clinicians regarding dosing, timing of use, and overall clinical situation The significant variation in PDP management in this study was noted to be a potential source of medical error, thus increasing the chance of adverse clinical event.

Push-dose pressor therapy can be employed for significant hypotension while more definitive therapy is being readied and applied. For instance, patients with significant hypotension requiring continuous vasopressor infusion can be managed with PDP while appropriate venous access is established, intravenous fluids are administered, and medications are prepared. The immediate period after resuscitation from cardiac arrest can be complicated by shock of many types. In fact, hypotension following ROSC in the cardiac arrest patient is not uncommon and has been identified as a risk issue associated with poor outcome. Prompt treatment of this altered perfusion may improve outcome. Gottlieb⁸ described three patients with ROSC after cardiac arrest. All three patients experienced significant, sustained hypotension with systolic blood pressure reading in the 50 to 60 mm Hg range; bolus-dose epinephrine was administered with significant improvement in the hemodynamic status while central venous access was established.

In a related clinical scenario, Schwartz et al⁹ considered the impact of PDP on central venous line (CVL) placement with continuous vasopressor infusion. In this ED study, although patients experienced an increase in BP, this impact was transient with approximately half of these individuals ultimately requiring CVL. In addition, serious adverse effect was noted more commonly in the phenylephrine-treated patients with “reactive” hypertension and ventricular tachycardia occurring in study patients.

Patient-Safety Considerations

In addition to the limited literature base supporting PDP use in the ED, another major significant issue focuses on safety concerns and adverse effects. Extremely limited data is available describing adverse events related to ED-administered PDP. Extrapolating from other EM and critical care administrations of peripheral epinephrine, both local and systemic adverse effects have been reported.^11,12 The range of adverse events noted in these studies are considerable, including local skin and soft-tissue injury (necrosis), end-organ tissue ischemia (eg, digits, tip of nose), acute hypertension, cardiac ischemic events, and left ventricular (LV) dysfunction.^11,12

When comparing peripheral infusion with central infusion, the risk of extravasation with resultant local tissue injury is markedly greater with peripheral vasopressor administration. In a systematic review of this issue, Loubani and Green¹¹ noted that such local adverse events were much more commonly associated with peripheral administration.

In another report of vasopressor use in the ED, Kanwar et al¹² described apparent confusion with epinephrine dosing and route of administration, resulting in very significant, systemic CV maladies, including severe elevations in BP, acute LV dysfunction, and chest pain associated with ST segment elevation.

It must be stressed that the publications by Loubani and Green¹¹ and Kanwar et al¹² described peripheral vasopressor administration: neither study included PDP therapy. Therefore, as previously noted, the aforementioned statements are extrapolated from when applied to PDP strategy.

Acquisto et al⁴ describe several errors in medication administration of PDP in the ED and other critical care areas of the hospital. In this report, all treating physicians were present at the patients’ bedside, either administering the medication or directly supervising its use. Agents involved included epinephrine and phenylephrine, delivered at exceedingly high doses. In their study, the authors noted several issues which they believe contributed to medication errors, including heterogeneity of pathology treated in these patients, apparent “earlier-than-appropriate” use of vasopressors (ie, prior to giving an appropriate fluid bolus), and medication preparation at the bedside by clinicians who may not possess the experience and training to mix these agents.

From a patient-safety perspective, Holden et al⁵ noted the potential for dosing error with significant adverse medical consequence related to PDP, as well as several contributing issues. First, they highlight the lack of a solid literature base to support administration of PDP in the ED and the development of decision-making guidelines for use in the ED. They also observed an inconsistency in approach to patient selection, medication choice, agent preparation, dosing, and other therapies. As seen in the Acquisto et al⁴ report, the patient-care scenarios are high risk and quite dynamic.

Conclusion

Bolus-dose vasopressor therapy is a potentially very useful treatment in the ED and other emergency/critical care settings. However, despite its benefits in treating patients in shock or with hypoperfusion, PDP is not widely used in EM due to the lack of studies, reviews, and guidelines in the literature to support its use in the ED. Such a literature base is required to provide an appropriate, safe means of patient selection, medication choice, dosing, and administration. Continued educational and research efforts are needed to more fully explore the use of PDP therapy in the ED.

When used correctly and appropriately, PDP has promise to be an important aid in the management of shock in the ED. Although bolus-dose therapy is appropriate for select clinical scenarios involving significant shock states which have the potential for progression to complete CV collapse without timely therapy, it is an adjunct to, not a replacement for commonly employed and medically indicated therapies such as crystalloid bolus or continuous vasopressor infusions.

It could happen. You are on a plane, perhaps on your way to a medical conference or a well-deserved vacation, when the flight attendant asks you to help a passenger experiencing an in-flight medical emergency. What is your role in this situation?

FLIGHT ATTENDANTS USED TO BE NURSES

Before World War II, nearly all American flight attendants were nurses, who could address most medical issues that arose during flights.¹ Airlines eliminated this preferential hiring practice to support the war effort. Traveling healthcare providers thereafter often volunteered to assist when in-flight medical issues arose, but aircraft carried minimal medical equipment and volunteers’ liability was uncertain.

In 1998, Congress passed the Aviation Medical Assistance Act (AMAA), which provides liability protection for on-board healthcare providers who render medical assistance. It also required the Federal Aviation Administration (FAA) to improve its standards for in-flight medical equipment.^2,3

HOW OFTEN DO EMERGENCIES ARISE?

How often medical events occur during flight is difficult to estimate because airlines are not mandated to report such issues.⁴ Based on data from a ground-based communications center that provides medical consultation service to airlines, medical events occur in approximately 1 in every 604 flights.⁵ This is likely an underestimate, as many medical events may be handled on board without involving a ground-based consultation center.

The most common emergencies are syncope or presyncope, representing 37.4% of consultations, followed by respiratory symptoms (12.1%), nausea or vomiting (9.5%), cardiac symptoms (7.7%), seizures (5.8%), and abdominal pain (4.1%).⁵ Very few in-flight medical emergencies progress to death; the reported mortality rate is 0.3%.⁵

CABIN PRESSURES ARE RELATIVELY LOW

The cabins of commercial airliners are pressurized, but the pressure is still lower than on the ground. The cabin pressure in flight is equivalent to that at an altitude of 6,000 to 8,000 feet,^6,7 ie, about 23 or 24 mm Hg, compared with about 30 mm Hg at sea level. At this pressure, passengers have a partial pressure of arterial oxygen (Pao₂) of 60 mm Hg (normal at sea level is > 80).⁸

This reduced oxygen pressure is typically not clinically meaningful in healthy people. However, people with underlying pulmonary or cardiac illness may be starting further to the left on the oxygen dissociation curve before gaining altitude, putting them at risk for acute exacerbations of underlying medical conditions. Many patients who rely on supplemental oxygen, such as those with chronic obstructive pulmonary disease, are advised to increase their oxygen support during flight.⁹

Boyle’s law says that the volume of a gas is inversely proportional to its pressure. As the pressure drops in the cabin after takeoff, air trapped in an enclosed space—eg, in some patient’s bodies—can increase in volume up to 30%,¹⁰ which can have medical ramifications. Clinically significant pneumothorax during flight has been reported.^11–13 Partially because of these volumetric changes, patients who have undergone abdominal surgery are advised to avoid flying for at least 2 weeks after their procedure.^10,14 Patients who have had recent ocular or intracranial surgery may also be at risk of in-flight complications.¹⁵

IN-FLIGHT MEDICAL RESOURCES

The limited medical supplies available on aircraft often challenge healthcare providers who offer to respond to in-flight medical events. However, several important medical resources are available.

Medical kits and defibrillators

FAA regulations require airlines based in the United States to carry basic first aid supplies such as bandages and splints.³ Airlines are also required to carry a medical kit containing the items listed in Table 1.

The FAA-mandated kit does not cover every circumstance that may arise. Although in-flight pediatric events occasionally occur,¹⁶ many of the available medications are inappropriate for young children. The FAA does not require sedative or antipsychotic agents, which could be useful for passengers who have acute psychiatric episodes. Obstetric supplies are absent. On international carriers, the contents of medical kits are highly variable,¹⁷ as are the names used for some medications.

The FAA requires at least 1 automated external defibrillator (AED) to be available on each commercial aircraft.³ The timely use of AEDs greatly improves survivability after out-of-hospital cardiac arrest.^18,19 One study involving a major US airline found a 40% survival rate to hospital discharge in patients who received in-flight defibrillation.²⁰ Without this intervention, very few of the patients would have been expected to survive. In addition to being clinically effective, placing AEDs aboard commercial aircraft is a cost-effective public health intervention.²¹

Most major airlines can contact ground-based medical consultation services during flight.¹⁰ These centers are staffed with healthcare providers who can provide flight crews with advice on how to handle medical events in real time. Healthcare providers can likewise discuss specific medical issues with these services if they respond to an in-flight medical event. Ground-based call centers can also communicate with prehospital providers should a flight need to be diverted.

Other on-board providers

Some medical events require the involvement of more than one medical provider. Other physicians, nurses, and prehospital providers are often also on board.²² Responding physicians can also request the assistance of these other healthcare providers. Flight attendants in the United States are required to be trained in cardiopulmonary resuscitation (CPR).²³

Flight diversion

Critically ill patients or those with time-sensitive medical emergencies may require the aircraft to divert from its intended destination. As may be expected, medical emergencies suspected to involve the cardiovascular, neurologic, or respiratory system have been shown to most likely result in aircraft diversion.^5,24 Approximately 7% of in-flight medical events in which a ground-based medical consultation service is contacted result in diversion.⁵

While an on-board responding physician can make a recommendation to divert based on the patient’s acute medical status, only the captain can make the ultimate decision.⁴ On-board healthcare providers should clearly state that a patient might benefit from an unscheduled landing if that is truly their assessment. In addition to communicating their clinical concerns with the flight crew, the responding physician may also be able to discuss the situation with the airline’s ground-based consultation service. On-board physicians can make important contributions to the assessment of illness severity and triage decisions.

MEDICOLEGAL ISSUES

No legal duty to assist

US healthcare providers are not legally required to respond to on-board medical emergencies on US-based airlines. Canada and the United Kingdom also do not require providers to render assistance. But the General Medical Council (the regulatory body for UK doctors) states that doctors have an ethical duty to respond in the event of a medical emergency, including one on board an aircraft. Other countries, notably Australia and some in the European Union, require healthcare professionals to respond to on-board medical emergencies.¹⁰

Regardless of potential legal duties to assist, healthcare providers are arguably ethically obliged to render assistance if they can.

Aviation Medical Assistance Act

The extent of an American healthcare provider’s liability risk for assisting in a medical emergency on a plane registered in the United States is limited by statute. The 1998 AMAA provides liability protection for on-board medical providers who are asked to assist during an in-flight medical emergency. This statute covers all US-certified air carriers on domestic flights and would likely be held to apply to US aircraft in foreign airspace because of the general rule that the law of the country where the air carrier is registered applies to in-flight events.

Under the AMAA, providers asked to assist with in-flight medical emergencies are not liable for malpractice as long as their actions are not “grossly” negligent or intended to cause the patient harm.²⁵ This is distinguishable from a standard malpractice liability scenario, in which the plaintiff only needs to show ordinary negligence. In a traditional healthcare setting, a provider has to act within the “standard of care” when assessing and treating a patient. If the provider deviates from the standard of care, such as by making an error in judgment or diagnosis, the provider is legally negligent. Under traditional malpractice law, even if a provider is minimally negligent, he or she is liable for any damages resulting from that negligence. Under a gross negligence standard, providers are protected from liability unless they demonstrate flagrant disregard for the patient’s health and safety.

Postflight issues

A provider who undertakes care should continue to provide care until it is no longer necessary, either because the patient recovers or the responsibility has been transferred to another provider. At the point of transfer, the healthcare provider’s relationship with the patient terminates.

The provider should document the encounter, typically using airline-specific documentation. The responding physician needs to be mindful of the patient’s privacy, refraining from discussing the event with others without the patient’s authorization.²⁶

Healthcare providers who wish to respond to in-flight medical emergencies must first determine if they are sufficiently capable of providing care. During a flight, providers do not expect to be on duty and so may have consumed alcoholic beverages to an extent that would potentially render them unsuitable to respond. When it is appropriate to become involved in a medical emergency during flight, the healthcare provider should state his or her qualifications to the passenger and to flight personnel.

If circumstances allow, the volunteer provider should obtain the patient’s consent for evaluation and treatment.¹⁰ Additionally, with the multilingual nature of commercial air travel, especially on international flights, the provider may need to enlist a translator’s assistance.

Providers may find it preferable to treat passengers in their seats.²⁷ Given the confined space in an aircraft, keeping ill passengers out of the aisle allows others to move about the cabin. If it becomes necessary to move the patient, a location should be sought that minimally interferes with other passengers’ needs.

If a passenger has critical medical needs, in-flight medical volunteers can recommend flight diversion, which should also be discussed with ground-based medical staff. However, as emphasized earlier, the captain makes the ultimate decision to divert, taking into account other operational factors that affect the safety of the aircraft and its occupants. In-flight medical care providers should perform only the treatments they are qualified to provide and should operate within their scope of training.

After the aircraft lands, if the passenger must be transported to a hospital, providers should supply prehospital personnel with a requisite transfer-of-care communication. In-flight medical providers who have performed a significant medical intervention might find it appropriate to accompany the patient to the hospital.

SPECIFIC CONDITIONS

The list of possible acute medical issues that occur aboard aircraft is extensive. Here are a few of them.

Trauma

Passengers may experience injuries during flight, for example during periods of heavy air turbulence. Responding physicians should assess for potential life-threatening injuries, keeping in mind that some passengers may be at higher risk. For example, if a passenger on anticoagulation experiences a blunt head injury, this would raise suspicion for possible intracranial hemorrhage, and frequent reassessment of neurologic status may be necessary. If an extremity fracture is suspected, the physician should splint the affected limb. Analgesia may be provided from the medical kit, if appropriate.

Gastrointestinal issues

Acute gastrointestinal issues such as nausea and vomiting are often reported to ground-based medical consultation services.⁵ Responding on-board providers must consider if the passenger is simply experiencing gastrointestinal upset from a benign condition such as gastroenteritis or has a more serious condition. For some patients, vomiting may be a symptom of a myocardial infarction.²⁸ Bilious emesis with abdominal distention may be associated with small-bowel obstruction. While antiemetics are not included in the FAA-mandated medical kit, providers can initiate intravenous fluid therapy for passengers who show signs of hypovolemia.

Cardiac arrest

Although cardiac arrest during flight is rare,⁵ medical providers should nonetheless be prepared to handle it. Upon recognition of cardiac arrest, the provider should immediately begin cardiopulmonary resuscitation and use the on-board AED to defibrillate a potentially shockable rhythm. Flight attendants are trained in cardiopulmonary resuscitation and therefore may assist with resuscitation efforts. If the patient is resuscitated, the responding physician should recommend diversion of the flight.

In the event of a severe life-threatening allergic reaction, the FAA-mandated emergency medical kit contains both diphenhydramine and epinephrine. For an adult experiencing anaphylaxis, a responding on-board physician can administer diphenhydramine 50 mg and epinephrine 0.3 mg (using the 1:1000 formulation), both intramuscularly. For patients with bronchospasm, a metered-dose inhaler of albuterol can be given. As anaphylaxis is an acute and potentially lethal condition, diversion of the aircraft would also be appropriate.²⁹

Myocardial infarction

When acute myocardial infarction is suspected, it is appropriate for the provider to give aspirin, with important exceptions for patients who are experiencing an acute hemorrhage or who have an aspirin allergy.³⁰ Supplemental oxygen should likewise be provided if the responding physician suspects compromised oxygenation. As acute myocardial infarction is also a time-sensitive condition, the clinician who suspects this diagnosis should recommend diversion of the aircraft.

Acute psychiatric issues

While approximately 2.4% of on-board medical events are attributed to psychiatric issues,⁵ there are few tools at the clinician’s disposal in the FAA-mandated emergency medical kit. Antipsychotics and sedatives are not included. The responding physician may need to attempt verbal de-escalation of aggressive behavior. If the safety of the flight is compromised, the application of improvised physical restraints may be appropriate.

Altered mental status

The differential diagnosis for altered mental status is extensive. The on-board physician should try to identify reversible and potentially lethal conditions and determine the potential need for aircraft diversion.

If possible, a blood sugar level should be measured (although the FAA-mandated kit does not contain a glucometer). It may be appropriate to empirically give intravenous dextrose to patients strongly suspected of having hypoglycemia.

If respiratory or cerebrovascular compromise is suspected, supplemental oxygen should be provided.

Unless a reversible cause of altered mental status is identified and treated successfully, it will likely be appropriate to recommend diversion of the aircraft.

Acknowledgment: The authors acknowledge Linda J. Kesselring, MS, ELS, the technical editor/writer in the Department of Emergency Medicine University of Maryland School of Medicine, for her contributions as copy editor of a previous version of this manuscript.

It could happen. You are on a plane, perhaps on your way to a medical conference or a well-deserved vacation, when the flight attendant asks you to help a passenger experiencing an in-flight medical emergency. What is your role in this situation?

FLIGHT ATTENDANTS USED TO BE NURSES

Before World War II, nearly all American flight attendants were nurses, who could address most medical issues that arose during flights.¹ Airlines eliminated this preferential hiring practice to support the war effort. Traveling healthcare providers thereafter often volunteered to assist when in-flight medical issues arose, but aircraft carried minimal medical equipment and volunteers’ liability was uncertain.

In 1998, Congress passed the Aviation Medical Assistance Act (AMAA), which provides liability protection for on-board healthcare providers who render medical assistance. It also required the Federal Aviation Administration (FAA) to improve its standards for in-flight medical equipment.^2,3

HOW OFTEN DO EMERGENCIES ARISE?

How often medical events occur during flight is difficult to estimate because airlines are not mandated to report such issues.⁴ Based on data from a ground-based communications center that provides medical consultation service to airlines, medical events occur in approximately 1 in every 604 flights.⁵ This is likely an underestimate, as many medical events may be handled on board without involving a ground-based consultation center.

The most common emergencies are syncope or presyncope, representing 37.4% of consultations, followed by respiratory symptoms (12.1%), nausea or vomiting (9.5%), cardiac symptoms (7.7%), seizures (5.8%), and abdominal pain (4.1%).⁵ Very few in-flight medical emergencies progress to death; the reported mortality rate is 0.3%.⁵

CABIN PRESSURES ARE RELATIVELY LOW

The cabins of commercial airliners are pressurized, but the pressure is still lower than on the ground. The cabin pressure in flight is equivalent to that at an altitude of 6,000 to 8,000 feet,^6,7 ie, about 23 or 24 mm Hg, compared with about 30 mm Hg at sea level. At this pressure, passengers have a partial pressure of arterial oxygen (Pao₂) of 60 mm Hg (normal at sea level is > 80).⁸

This reduced oxygen pressure is typically not clinically meaningful in healthy people. However, people with underlying pulmonary or cardiac illness may be starting further to the left on the oxygen dissociation curve before gaining altitude, putting them at risk for acute exacerbations of underlying medical conditions. Many patients who rely on supplemental oxygen, such as those with chronic obstructive pulmonary disease, are advised to increase their oxygen support during flight.⁹

Boyle’s law says that the volume of a gas is inversely proportional to its pressure. As the pressure drops in the cabin after takeoff, air trapped in an enclosed space—eg, in some patient’s bodies—can increase in volume up to 30%,¹⁰ which can have medical ramifications. Clinically significant pneumothorax during flight has been reported.^11–13 Partially because of these volumetric changes, patients who have undergone abdominal surgery are advised to avoid flying for at least 2 weeks after their procedure.^10,14 Patients who have had recent ocular or intracranial surgery may also be at risk of in-flight complications.¹⁵

IN-FLIGHT MEDICAL RESOURCES

The limited medical supplies available on aircraft often challenge healthcare providers who offer to respond to in-flight medical events. However, several important medical resources are available.

Medical kits and defibrillators

FAA regulations require airlines based in the United States to carry basic first aid supplies such as bandages and splints.³ Airlines are also required to carry a medical kit containing the items listed in Table 1.

The FAA-mandated kit does not cover every circumstance that may arise. Although in-flight pediatric events occasionally occur,¹⁶ many of the available medications are inappropriate for young children. The FAA does not require sedative or antipsychotic agents, which could be useful for passengers who have acute psychiatric episodes. Obstetric supplies are absent. On international carriers, the contents of medical kits are highly variable,¹⁷ as are the names used for some medications.

The FAA requires at least 1 automated external defibrillator (AED) to be available on each commercial aircraft.³ The timely use of AEDs greatly improves survivability after out-of-hospital cardiac arrest.^18,19 One study involving a major US airline found a 40% survival rate to hospital discharge in patients who received in-flight defibrillation.²⁰ Without this intervention, very few of the patients would have been expected to survive. In addition to being clinically effective, placing AEDs aboard commercial aircraft is a cost-effective public health intervention.²¹

Most major airlines can contact ground-based medical consultation services during flight.¹⁰ These centers are staffed with healthcare providers who can provide flight crews with advice on how to handle medical events in real time. Healthcare providers can likewise discuss specific medical issues with these services if they respond to an in-flight medical event. Ground-based call centers can also communicate with prehospital providers should a flight need to be diverted.

Other on-board providers

Some medical events require the involvement of more than one medical provider. Other physicians, nurses, and prehospital providers are often also on board.²² Responding physicians can also request the assistance of these other healthcare providers. Flight attendants in the United States are required to be trained in cardiopulmonary resuscitation (CPR).²³

Flight diversion

Critically ill patients or those with time-sensitive medical emergencies may require the aircraft to divert from its intended destination. As may be expected, medical emergencies suspected to involve the cardiovascular, neurologic, or respiratory system have been shown to most likely result in aircraft diversion.^5,24 Approximately 7% of in-flight medical events in which a ground-based medical consultation service is contacted result in diversion.⁵

While an on-board responding physician can make a recommendation to divert based on the patient’s acute medical status, only the captain can make the ultimate decision.⁴ On-board healthcare providers should clearly state that a patient might benefit from an unscheduled landing if that is truly their assessment. In addition to communicating their clinical concerns with the flight crew, the responding physician may also be able to discuss the situation with the airline’s ground-based consultation service. On-board physicians can make important contributions to the assessment of illness severity and triage decisions.

MEDICOLEGAL ISSUES

No legal duty to assist

US healthcare providers are not legally required to respond to on-board medical emergencies on US-based airlines. Canada and the United Kingdom also do not require providers to render assistance. But the General Medical Council (the regulatory body for UK doctors) states that doctors have an ethical duty to respond in the event of a medical emergency, including one on board an aircraft. Other countries, notably Australia and some in the European Union, require healthcare professionals to respond to on-board medical emergencies.¹⁰

Regardless of potential legal duties to assist, healthcare providers are arguably ethically obliged to render assistance if they can.

Aviation Medical Assistance Act

The extent of an American healthcare provider’s liability risk for assisting in a medical emergency on a plane registered in the United States is limited by statute. The 1998 AMAA provides liability protection for on-board medical providers who are asked to assist during an in-flight medical emergency. This statute covers all US-certified air carriers on domestic flights and would likely be held to apply to US aircraft in foreign airspace because of the general rule that the law of the country where the air carrier is registered applies to in-flight events.

Under the AMAA, providers asked to assist with in-flight medical emergencies are not liable for malpractice as long as their actions are not “grossly” negligent or intended to cause the patient harm.²⁵ This is distinguishable from a standard malpractice liability scenario, in which the plaintiff only needs to show ordinary negligence. In a traditional healthcare setting, a provider has to act within the “standard of care” when assessing and treating a patient. If the provider deviates from the standard of care, such as by making an error in judgment or diagnosis, the provider is legally negligent. Under traditional malpractice law, even if a provider is minimally negligent, he or she is liable for any damages resulting from that negligence. Under a gross negligence standard, providers are protected from liability unless they demonstrate flagrant disregard for the patient’s health and safety.

Postflight issues

A provider who undertakes care should continue to provide care until it is no longer necessary, either because the patient recovers or the responsibility has been transferred to another provider. At the point of transfer, the healthcare provider’s relationship with the patient terminates.

The provider should document the encounter, typically using airline-specific documentation. The responding physician needs to be mindful of the patient’s privacy, refraining from discussing the event with others without the patient’s authorization.²⁶

Healthcare providers who wish to respond to in-flight medical emergencies must first determine if they are sufficiently capable of providing care. During a flight, providers do not expect to be on duty and so may have consumed alcoholic beverages to an extent that would potentially render them unsuitable to respond. When it is appropriate to become involved in a medical emergency during flight, the healthcare provider should state his or her qualifications to the passenger and to flight personnel.

If circumstances allow, the volunteer provider should obtain the patient’s consent for evaluation and treatment.¹⁰ Additionally, with the multilingual nature of commercial air travel, especially on international flights, the provider may need to enlist a translator’s assistance.

Providers may find it preferable to treat passengers in their seats.²⁷ Given the confined space in an aircraft, keeping ill passengers out of the aisle allows others to move about the cabin. If it becomes necessary to move the patient, a location should be sought that minimally interferes with other passengers’ needs.

If a passenger has critical medical needs, in-flight medical volunteers can recommend flight diversion, which should also be discussed with ground-based medical staff. However, as emphasized earlier, the captain makes the ultimate decision to divert, taking into account other operational factors that affect the safety of the aircraft and its occupants. In-flight medical care providers should perform only the treatments they are qualified to provide and should operate within their scope of training.

After the aircraft lands, if the passenger must be transported to a hospital, providers should supply prehospital personnel with a requisite transfer-of-care communication. In-flight medical providers who have performed a significant medical intervention might find it appropriate to accompany the patient to the hospital.

SPECIFIC CONDITIONS

The list of possible acute medical issues that occur aboard aircraft is extensive. Here are a few of them.

Trauma

Passengers may experience injuries during flight, for example during periods of heavy air turbulence. Responding physicians should assess for potential life-threatening injuries, keeping in mind that some passengers may be at higher risk. For example, if a passenger on anticoagulation experiences a blunt head injury, this would raise suspicion for possible intracranial hemorrhage, and frequent reassessment of neurologic status may be necessary. If an extremity fracture is suspected, the physician should splint the affected limb. Analgesia may be provided from the medical kit, if appropriate.

Gastrointestinal issues

Acute gastrointestinal issues such as nausea and vomiting are often reported to ground-based medical consultation services.⁵ Responding on-board providers must consider if the passenger is simply experiencing gastrointestinal upset from a benign condition such as gastroenteritis or has a more serious condition. For some patients, vomiting may be a symptom of a myocardial infarction.²⁸ Bilious emesis with abdominal distention may be associated with small-bowel obstruction. While antiemetics are not included in the FAA-mandated medical kit, providers can initiate intravenous fluid therapy for passengers who show signs of hypovolemia.

Cardiac arrest

Although cardiac arrest during flight is rare,⁵ medical providers should nonetheless be prepared to handle it. Upon recognition of cardiac arrest, the provider should immediately begin cardiopulmonary resuscitation and use the on-board AED to defibrillate a potentially shockable rhythm. Flight attendants are trained in cardiopulmonary resuscitation and therefore may assist with resuscitation efforts. If the patient is resuscitated, the responding physician should recommend diversion of the flight.

In the event of a severe life-threatening allergic reaction, the FAA-mandated emergency medical kit contains both diphenhydramine and epinephrine. For an adult experiencing anaphylaxis, a responding on-board physician can administer diphenhydramine 50 mg and epinephrine 0.3 mg (using the 1:1000 formulation), both intramuscularly. For patients with bronchospasm, a metered-dose inhaler of albuterol can be given. As anaphylaxis is an acute and potentially lethal condition, diversion of the aircraft would also be appropriate.²⁹

Myocardial infarction

When acute myocardial infarction is suspected, it is appropriate for the provider to give aspirin, with important exceptions for patients who are experiencing an acute hemorrhage or who have an aspirin allergy.³⁰ Supplemental oxygen should likewise be provided if the responding physician suspects compromised oxygenation. As acute myocardial infarction is also a time-sensitive condition, the clinician who suspects this diagnosis should recommend diversion of the aircraft.

Acute psychiatric issues

While approximately 2.4% of on-board medical events are attributed to psychiatric issues,⁵ there are few tools at the clinician’s disposal in the FAA-mandated emergency medical kit. Antipsychotics and sedatives are not included. The responding physician may need to attempt verbal de-escalation of aggressive behavior. If the safety of the flight is compromised, the application of improvised physical restraints may be appropriate.

Altered mental status

The differential diagnosis for altered mental status is extensive. The on-board physician should try to identify reversible and potentially lethal conditions and determine the potential need for aircraft diversion.

If possible, a blood sugar level should be measured (although the FAA-mandated kit does not contain a glucometer). It may be appropriate to empirically give intravenous dextrose to patients strongly suspected of having hypoglycemia.

If respiratory or cerebrovascular compromise is suspected, supplemental oxygen should be provided.

Unless a reversible cause of altered mental status is identified and treated successfully, it will likely be appropriate to recommend diversion of the aircraft.

Acknowledgment: The authors acknowledge Linda J. Kesselring, MS, ELS, the technical editor/writer in the Department of Emergency Medicine University of Maryland School of Medicine, for her contributions as copy editor of a previous version of this manuscript.

It could happen. You are on a plane, perhaps on your way to a medical conference or a well-deserved vacation, when the flight attendant asks you to help a passenger experiencing an in-flight medical emergency. What is your role in this situation?

FLIGHT ATTENDANTS USED TO BE NURSES

Before World War II, nearly all American flight attendants were nurses, who could address most medical issues that arose during flights.¹ Airlines eliminated this preferential hiring practice to support the war effort. Traveling healthcare providers thereafter often volunteered to assist when in-flight medical issues arose, but aircraft carried minimal medical equipment and volunteers’ liability was uncertain.

In 1998, Congress passed the Aviation Medical Assistance Act (AMAA), which provides liability protection for on-board healthcare providers who render medical assistance. It also required the Federal Aviation Administration (FAA) to improve its standards for in-flight medical equipment.^2,3

HOW OFTEN DO EMERGENCIES ARISE?

How often medical events occur during flight is difficult to estimate because airlines are not mandated to report such issues.⁴ Based on data from a ground-based communications center that provides medical consultation service to airlines, medical events occur in approximately 1 in every 604 flights.⁵ This is likely an underestimate, as many medical events may be handled on board without involving a ground-based consultation center.

The most common emergencies are syncope or presyncope, representing 37.4% of consultations, followed by respiratory symptoms (12.1%), nausea or vomiting (9.5%), cardiac symptoms (7.7%), seizures (5.8%), and abdominal pain (4.1%).⁵ Very few in-flight medical emergencies progress to death; the reported mortality rate is 0.3%.⁵

CABIN PRESSURES ARE RELATIVELY LOW

The cabins of commercial airliners are pressurized, but the pressure is still lower than on the ground. The cabin pressure in flight is equivalent to that at an altitude of 6,000 to 8,000 feet,^6,7 ie, about 23 or 24 mm Hg, compared with about 30 mm Hg at sea level. At this pressure, passengers have a partial pressure of arterial oxygen (Pao₂) of 60 mm Hg (normal at sea level is > 80).⁸

This reduced oxygen pressure is typically not clinically meaningful in healthy people. However, people with underlying pulmonary or cardiac illness may be starting further to the left on the oxygen dissociation curve before gaining altitude, putting them at risk for acute exacerbations of underlying medical conditions. Many patients who rely on supplemental oxygen, such as those with chronic obstructive pulmonary disease, are advised to increase their oxygen support during flight.⁹

Boyle’s law says that the volume of a gas is inversely proportional to its pressure. As the pressure drops in the cabin after takeoff, air trapped in an enclosed space—eg, in some patient’s bodies—can increase in volume up to 30%,¹⁰ which can have medical ramifications. Clinically significant pneumothorax during flight has been reported.^11–13 Partially because of these volumetric changes, patients who have undergone abdominal surgery are advised to avoid flying for at least 2 weeks after their procedure.^10,14 Patients who have had recent ocular or intracranial surgery may also be at risk of in-flight complications.¹⁵

IN-FLIGHT MEDICAL RESOURCES

The limited medical supplies available on aircraft often challenge healthcare providers who offer to respond to in-flight medical events. However, several important medical resources are available.

Medical kits and defibrillators

FAA regulations require airlines based in the United States to carry basic first aid supplies such as bandages and splints.³ Airlines are also required to carry a medical kit containing the items listed in Table 1.

The FAA-mandated kit does not cover every circumstance that may arise. Although in-flight pediatric events occasionally occur,¹⁶ many of the available medications are inappropriate for young children. The FAA does not require sedative or antipsychotic agents, which could be useful for passengers who have acute psychiatric episodes. Obstetric supplies are absent. On international carriers, the contents of medical kits are highly variable,¹⁷ as are the names used for some medications.

The FAA requires at least 1 automated external defibrillator (AED) to be available on each commercial aircraft.³ The timely use of AEDs greatly improves survivability after out-of-hospital cardiac arrest.^18,19 One study involving a major US airline found a 40% survival rate to hospital discharge in patients who received in-flight defibrillation.²⁰ Without this intervention, very few of the patients would have been expected to survive. In addition to being clinically effective, placing AEDs aboard commercial aircraft is a cost-effective public health intervention.²¹

Most major airlines can contact ground-based medical consultation services during flight.¹⁰ These centers are staffed with healthcare providers who can provide flight crews with advice on how to handle medical events in real time. Healthcare providers can likewise discuss specific medical issues with these services if they respond to an in-flight medical event. Ground-based call centers can also communicate with prehospital providers should a flight need to be diverted.

Other on-board providers

Some medical events require the involvement of more than one medical provider. Other physicians, nurses, and prehospital providers are often also on board.²² Responding physicians can also request the assistance of these other healthcare providers. Flight attendants in the United States are required to be trained in cardiopulmonary resuscitation (CPR).²³

Flight diversion

Critically ill patients or those with time-sensitive medical emergencies may require the aircraft to divert from its intended destination. As may be expected, medical emergencies suspected to involve the cardiovascular, neurologic, or respiratory system have been shown to most likely result in aircraft diversion.^5,24 Approximately 7% of in-flight medical events in which a ground-based medical consultation service is contacted result in diversion.⁵

While an on-board responding physician can make a recommendation to divert based on the patient’s acute medical status, only the captain can make the ultimate decision.⁴ On-board healthcare providers should clearly state that a patient might benefit from an unscheduled landing if that is truly their assessment. In addition to communicating their clinical concerns with the flight crew, the responding physician may also be able to discuss the situation with the airline’s ground-based consultation service. On-board physicians can make important contributions to the assessment of illness severity and triage decisions.

MEDICOLEGAL ISSUES

No legal duty to assist

US healthcare providers are not legally required to respond to on-board medical emergencies on US-based airlines. Canada and the United Kingdom also do not require providers to render assistance. But the General Medical Council (the regulatory body for UK doctors) states that doctors have an ethical duty to respond in the event of a medical emergency, including one on board an aircraft. Other countries, notably Australia and some in the European Union, require healthcare professionals to respond to on-board medical emergencies.¹⁰

Regardless of potential legal duties to assist, healthcare providers are arguably ethically obliged to render assistance if they can.

Aviation Medical Assistance Act

The extent of an American healthcare provider’s liability risk for assisting in a medical emergency on a plane registered in the United States is limited by statute. The 1998 AMAA provides liability protection for on-board medical providers who are asked to assist during an in-flight medical emergency. This statute covers all US-certified air carriers on domestic flights and would likely be held to apply to US aircraft in foreign airspace because of the general rule that the law of the country where the air carrier is registered applies to in-flight events.

Under the AMAA, providers asked to assist with in-flight medical emergencies are not liable for malpractice as long as their actions are not “grossly” negligent or intended to cause the patient harm.²⁵ This is distinguishable from a standard malpractice liability scenario, in which the plaintiff only needs to show ordinary negligence. In a traditional healthcare setting, a provider has to act within the “standard of care” when assessing and treating a patient. If the provider deviates from the standard of care, such as by making an error in judgment or diagnosis, the provider is legally negligent. Under traditional malpractice law, even if a provider is minimally negligent, he or she is liable for any damages resulting from that negligence. Under a gross negligence standard, providers are protected from liability unless they demonstrate flagrant disregard for the patient’s health and safety.

Postflight issues

A provider who undertakes care should continue to provide care until it is no longer necessary, either because the patient recovers or the responsibility has been transferred to another provider. At the point of transfer, the healthcare provider’s relationship with the patient terminates.

The provider should document the encounter, typically using airline-specific documentation. The responding physician needs to be mindful of the patient’s privacy, refraining from discussing the event with others without the patient’s authorization.²⁶

Healthcare providers who wish to respond to in-flight medical emergencies must first determine if they are sufficiently capable of providing care. During a flight, providers do not expect to be on duty and so may have consumed alcoholic beverages to an extent that would potentially render them unsuitable to respond. When it is appropriate to become involved in a medical emergency during flight, the healthcare provider should state his or her qualifications to the passenger and to flight personnel.

If circumstances allow, the volunteer provider should obtain the patient’s consent for evaluation and treatment.¹⁰ Additionally, with the multilingual nature of commercial air travel, especially on international flights, the provider may need to enlist a translator’s assistance.

Providers may find it preferable to treat passengers in their seats.²⁷ Given the confined space in an aircraft, keeping ill passengers out of the aisle allows others to move about the cabin. If it becomes necessary to move the patient, a location should be sought that minimally interferes with other passengers’ needs.

If a passenger has critical medical needs, in-flight medical volunteers can recommend flight diversion, which should also be discussed with ground-based medical staff. However, as emphasized earlier, the captain makes the ultimate decision to divert, taking into account other operational factors that affect the safety of the aircraft and its occupants. In-flight medical care providers should perform only the treatments they are qualified to provide and should operate within their scope of training.

After the aircraft lands, if the passenger must be transported to a hospital, providers should supply prehospital personnel with a requisite transfer-of-care communication. In-flight medical providers who have performed a significant medical intervention might find it appropriate to accompany the patient to the hospital.

SPECIFIC CONDITIONS

The list of possible acute medical issues that occur aboard aircraft is extensive. Here are a few of them.

Trauma

Passengers may experience injuries during flight, for example during periods of heavy air turbulence. Responding physicians should assess for potential life-threatening injuries, keeping in mind that some passengers may be at higher risk. For example, if a passenger on anticoagulation experiences a blunt head injury, this would raise suspicion for possible intracranial hemorrhage, and frequent reassessment of neurologic status may be necessary. If an extremity fracture is suspected, the physician should splint the affected limb. Analgesia may be provided from the medical kit, if appropriate.

Gastrointestinal issues

Acute gastrointestinal issues such as nausea and vomiting are often reported to ground-based medical consultation services.⁵ Responding on-board providers must consider if the passenger is simply experiencing gastrointestinal upset from a benign condition such as gastroenteritis or has a more serious condition. For some patients, vomiting may be a symptom of a myocardial infarction.²⁸ Bilious emesis with abdominal distention may be associated with small-bowel obstruction. While antiemetics are not included in the FAA-mandated medical kit, providers can initiate intravenous fluid therapy for passengers who show signs of hypovolemia.

Cardiac arrest

Although cardiac arrest during flight is rare,⁵ medical providers should nonetheless be prepared to handle it. Upon recognition of cardiac arrest, the provider should immediately begin cardiopulmonary resuscitation and use the on-board AED to defibrillate a potentially shockable rhythm. Flight attendants are trained in cardiopulmonary resuscitation and therefore may assist with resuscitation efforts. If the patient is resuscitated, the responding physician should recommend diversion of the flight.

In the event of a severe life-threatening allergic reaction, the FAA-mandated emergency medical kit contains both diphenhydramine and epinephrine. For an adult experiencing anaphylaxis, a responding on-board physician can administer diphenhydramine 50 mg and epinephrine 0.3 mg (using the 1:1000 formulation), both intramuscularly. For patients with bronchospasm, a metered-dose inhaler of albuterol can be given. As anaphylaxis is an acute and potentially lethal condition, diversion of the aircraft would also be appropriate.²⁹

Myocardial infarction

When acute myocardial infarction is suspected, it is appropriate for the provider to give aspirin, with important exceptions for patients who are experiencing an acute hemorrhage or who have an aspirin allergy.³⁰ Supplemental oxygen should likewise be provided if the responding physician suspects compromised oxygenation. As acute myocardial infarction is also a time-sensitive condition, the clinician who suspects this diagnosis should recommend diversion of the aircraft.

Acute psychiatric issues

While approximately 2.4% of on-board medical events are attributed to psychiatric issues,⁵ there are few tools at the clinician’s disposal in the FAA-mandated emergency medical kit. Antipsychotics and sedatives are not included. The responding physician may need to attempt verbal de-escalation of aggressive behavior. If the safety of the flight is compromised, the application of improvised physical restraints may be appropriate.

Altered mental status

The differential diagnosis for altered mental status is extensive. The on-board physician should try to identify reversible and potentially lethal conditions and determine the potential need for aircraft diversion.

If possible, a blood sugar level should be measured (although the FAA-mandated kit does not contain a glucometer). It may be appropriate to empirically give intravenous dextrose to patients strongly suspected of having hypoglycemia.

If respiratory or cerebrovascular compromise is suspected, supplemental oxygen should be provided.

Unless a reversible cause of altered mental status is identified and treated successfully, it will likely be appropriate to recommend diversion of the aircraft.

Acknowledgment: The authors acknowledge Linda J. Kesselring, MS, ELS, the technical editor/writer in the Department of Emergency Medicine University of Maryland School of Medicine, for her contributions as copy editor of a previous version of this manuscript.