What If? Study Results Challenge VTE Pathophysiology

Post-trauma deep vein thrombosis and pulmonary embolism diagnoses in severely injured blunt trauma patients were associated with different clinical risk factors, leading researchers to consider that the two "may represent distinct pathophysiologic entities."

At the meeting, Dr. Scott C. Brakenridge also pointed to other recent findings, including a study that found that more than half of pulmonary embolism (PE) cases are diagnosed within the first few days of injury (Am. J. Surg. 2011;201:209-15).

"We believe these findings bring into question whether the conventional wisdom of peripheral thrombosis and subsequent embolism is an oversimplification of thromboembolic pathophysiology after injury," said Dr. Brakenridge, a trauma/surgical critical care and vascular surgery fellow, at Harborview Medical Center and the University of Washington, Seattle.

In the multicenter prospective observational study, he and his coinvestigators compared clinical risk factors for deep vein thrombosis (DVT) and PE in 1,822 severely injured blunt trauma patients with evidence of hemorrhagic shock, treated at one of five urban trauma centers from 2002 to 2011. Most were male, their median age was 41 years, and the median injury severity score was 33; they received a mean of 6 U of packed red blood cells and 12 L crystalloid resuscitation over the first 24 hours.

Within 28 days of injury, 95 patients (5.1%) were diagnosed with a DVT and 83 (3.9%) were diagnosed with a PE; the total number of patients diagnosed with the traditional composite end point of venous thromboembolism (VTE) was 159 (8.5%). Of the 159 patients with VTE, only 6% (9 patients) were diagnosed with both DVT and PE.

Risk factors for the composite end point VTE resembled those from other studies. However, when analyzed individually, DVT and PE exhibited differences in their risk-factor profiles. The independent risk factors identified among those diagnosed with a DVT were failure to initiate prophylaxis within the first 48 hours, a thoracic abbreviated injury score of 3 or more, and body mass index above 28 kg/m². Independent risk factors for PE were serum lactate greater than 5 mmol/L and male gender. The median times to diagnosis of DVT and PE were similar at approximately 10 days.

These results indicate that the risk factors for a clinical DVT diagnosis after severe blunt trauma "appear to represent the inability to initiate prompt pharmacologic prophylaxis, overall injury burden and obesity, while risk factors for PE are gender specific and consistent with a severe shock state." Dr. Brakenridge said.

Mechanistically, he and his associates are suggesting that while a predisposition to DVT and PE may share "a postinjury hypercoagulopathic state ... their discordance may be secondary to differences in local factors such as tissue injury, stasis, and endothelial damage, as well as systemic influences such as a severe shock state," he added.

The study had limitations, including a lack of standardized DVT screening protocols, and more prospective studies that evaluate the pathophysiology, diagnosis, and treatment of DVT and PE early after injury are needed, Dr. Brakenridge said. "If borne out in future prospective studies, this could have significant implications for the diagnosis, and treatment of postinjury DVT and PE," he added.

Dr. Brakenridge and his coinvestigators reported having no disclosures.

Post-trauma deep vein thrombosis and pulmonary embolism diagnoses in severely injured blunt trauma patients were associated with different clinical risk factors, leading researchers to consider that the two "may represent distinct pathophysiologic entities."

At the meeting, Dr. Scott C. Brakenridge also pointed to other recent findings, including a study that found that more than half of pulmonary embolism (PE) cases are diagnosed within the first few days of injury (Am. J. Surg. 2011;201:209-15).

"We believe these findings bring into question whether the conventional wisdom of peripheral thrombosis and subsequent embolism is an oversimplification of thromboembolic pathophysiology after injury," said Dr. Brakenridge, a trauma/surgical critical care and vascular surgery fellow, at Harborview Medical Center and the University of Washington, Seattle.

In the multicenter prospective observational study, he and his coinvestigators compared clinical risk factors for deep vein thrombosis (DVT) and PE in 1,822 severely injured blunt trauma patients with evidence of hemorrhagic shock, treated at one of five urban trauma centers from 2002 to 2011. Most were male, their median age was 41 years, and the median injury severity score was 33; they received a mean of 6 U of packed red blood cells and 12 L crystalloid resuscitation over the first 24 hours.

Within 28 days of injury, 95 patients (5.1%) were diagnosed with a DVT and 83 (3.9%) were diagnosed with a PE; the total number of patients diagnosed with the traditional composite end point of venous thromboembolism (VTE) was 159 (8.5%). Of the 159 patients with VTE, only 6% (9 patients) were diagnosed with both DVT and PE.

Risk factors for the composite end point VTE resembled those from other studies. However, when analyzed individually, DVT and PE exhibited differences in their risk-factor profiles. The independent risk factors identified among those diagnosed with a DVT were failure to initiate prophylaxis within the first 48 hours, a thoracic abbreviated injury score of 3 or more, and body mass index above 28 kg/m². Independent risk factors for PE were serum lactate greater than 5 mmol/L and male gender. The median times to diagnosis of DVT and PE were similar at approximately 10 days.

These results indicate that the risk factors for a clinical DVT diagnosis after severe blunt trauma "appear to represent the inability to initiate prompt pharmacologic prophylaxis, overall injury burden and obesity, while risk factors for PE are gender specific and consistent with a severe shock state." Dr. Brakenridge said.

Mechanistically, he and his associates are suggesting that while a predisposition to DVT and PE may share "a postinjury hypercoagulopathic state ... their discordance may be secondary to differences in local factors such as tissue injury, stasis, and endothelial damage, as well as systemic influences such as a severe shock state," he added.

The study had limitations, including a lack of standardized DVT screening protocols, and more prospective studies that evaluate the pathophysiology, diagnosis, and treatment of DVT and PE early after injury are needed, Dr. Brakenridge said. "If borne out in future prospective studies, this could have significant implications for the diagnosis, and treatment of postinjury DVT and PE," he added.

Dr. Brakenridge and his coinvestigators reported having no disclosures.

Post-trauma deep vein thrombosis and pulmonary embolism diagnoses in severely injured blunt trauma patients were associated with different clinical risk factors, leading researchers to consider that the two "may represent distinct pathophysiologic entities."

At the meeting, Dr. Scott C. Brakenridge also pointed to other recent findings, including a study that found that more than half of pulmonary embolism (PE) cases are diagnosed within the first few days of injury (Am. J. Surg. 2011;201:209-15).

"We believe these findings bring into question whether the conventional wisdom of peripheral thrombosis and subsequent embolism is an oversimplification of thromboembolic pathophysiology after injury," said Dr. Brakenridge, a trauma/surgical critical care and vascular surgery fellow, at Harborview Medical Center and the University of Washington, Seattle.

In the multicenter prospective observational study, he and his coinvestigators compared clinical risk factors for deep vein thrombosis (DVT) and PE in 1,822 severely injured blunt trauma patients with evidence of hemorrhagic shock, treated at one of five urban trauma centers from 2002 to 2011. Most were male, their median age was 41 years, and the median injury severity score was 33; they received a mean of 6 U of packed red blood cells and 12 L crystalloid resuscitation over the first 24 hours.

Within 28 days of injury, 95 patients (5.1%) were diagnosed with a DVT and 83 (3.9%) were diagnosed with a PE; the total number of patients diagnosed with the traditional composite end point of venous thromboembolism (VTE) was 159 (8.5%). Of the 159 patients with VTE, only 6% (9 patients) were diagnosed with both DVT and PE.

Risk factors for the composite end point VTE resembled those from other studies. However, when analyzed individually, DVT and PE exhibited differences in their risk-factor profiles. The independent risk factors identified among those diagnosed with a DVT were failure to initiate prophylaxis within the first 48 hours, a thoracic abbreviated injury score of 3 or more, and body mass index above 28 kg/m². Independent risk factors for PE were serum lactate greater than 5 mmol/L and male gender. The median times to diagnosis of DVT and PE were similar at approximately 10 days.

These results indicate that the risk factors for a clinical DVT diagnosis after severe blunt trauma "appear to represent the inability to initiate prompt pharmacologic prophylaxis, overall injury burden and obesity, while risk factors for PE are gender specific and consistent with a severe shock state." Dr. Brakenridge said.

Mechanistically, he and his associates are suggesting that while a predisposition to DVT and PE may share "a postinjury hypercoagulopathic state ... their discordance may be secondary to differences in local factors such as tissue injury, stasis, and endothelial damage, as well as systemic influences such as a severe shock state," he added.

The study had limitations, including a lack of standardized DVT screening protocols, and more prospective studies that evaluate the pathophysiology, diagnosis, and treatment of DVT and PE early after injury are needed, Dr. Brakenridge said. "If borne out in future prospective studies, this could have significant implications for the diagnosis, and treatment of postinjury DVT and PE," he added.

Dr. Brakenridge and his coinvestigators reported having no disclosures.