Automatic Airway Pressure Devices Can Treat Simple Apnea

SCOTTSDALE, ARIZ. — Automatic devices that adjust continuous positive airway pressure in response to changes in airway resistance or flow are as effective as conventional machines for the treatment of uncomplicated obstructive sleep apnea, Dr. Neil S. Freedman said at a meeting on sleep medicine sponsored by the American College of Chest Physicians.

AutoCPAP (APAP) will never be superior to fixed continuous positive airway pressure (CPAP) as a treatment, but it offers two advantages: faster treatment of apnea, and the potential for lower costs, according to Dr. Freedman, who is with a group practice that specializes in sleep disorders in Bannockburn, Ill., and the sleep center at Lake Forest (Ill.) Hospital.

Citing long waits for sleep studies, he said that he will put a patient on APAP pending a sleep study if the person weighs 300 pounds, snores, has had observed apnea, and is drowsy during the day. In such cases, he said, the sleep study must still be done within 30 days to secure reimbursement and to determine pressures.

Although attended APAP in a sleep laboratory is currently accepted as useful for titrating fixed CPAP pressures in uncomplicated patients, Dr. Freedman said that unattended APAP has not been established as useful for that purpose. Unattended APAP also is not established as a treatment for patients who have never used CPAP, but Dr. Freedman said this may no longer be valid.

He cited a randomized controlled trial in which 360 patients were randomized to standard CPAP, APAP titrated at home, or titration at home by a predicted formula (Am. J. Respir. Crit. Care Med. 2004;170:1218–24). Successful home titration of APAP went from 83% on the first try to 96% on the second try. All groups had equivalent improvements in quality of life, and nearly all patients wanted to continue the treatments to which they had been assigned.

Dr. Freedman listed various monikers for the new technology—automated, auto-titrating, auto-adjusting, and self-titrating—but settled on APAP as a common term. The devices vary considerably in efficacy, he advised, and their role in treating obstructive sleep apnea is not well defined.

“All APAPs are not the same,” he said, warning against generalizing conclusions from clinical studies of any one APAP technology to APAP devices as a class.

He emphasized that the devices use different detection methods, employ different algorithms, and have different response times. Notably, whereas some monitor inspiratory flow, others measure resistance.

“They all respond in different ways,” he said. “Nobody knows what the best algorithm is.”

Among the studies he cited was a benchmark testing of five APAP machines (Eur. Respir. J. 2004;24:649–58). All five suppressed obstructive apnea, but none suppressed flow limitation. The investigators reported considerable variation in residual hypopnea, control of snoring, and response to mask leaks. Four of the machines inappropriately increased pressure in response to central apnea.

Dr. Freedman suggested APAP machines that use a forced oscillation technique (FOT) may be better suited than flow-based APAP for evaluation of central apnea.

“You don't want a machine to make central apnea worse,” he said.

APAP should not be used to treat patients who hyperventilate, have heart failure or COPD/chronic lung disease, or do not snore, according to Dr. Freedman. All these conditions have been excluded from the studies performed so far.

He said the lack of data also makes APAP's efficacy unclear for obstructive sleep apneas that are related to rapid eye movement, are position dependent, involve high pressures, or occur in patients who are intolerant of CPAP.

AutoCPAP will never be superior to fixed CPAP, but it's faster and less expensive. DR. FREEDMAN

SCOTTSDALE, ARIZ. — Automatic devices that adjust continuous positive airway pressure in response to changes in airway resistance or flow are as effective as conventional machines for the treatment of uncomplicated obstructive sleep apnea, Dr. Neil S. Freedman said at a meeting on sleep medicine sponsored by the American College of Chest Physicians.

AutoCPAP (APAP) will never be superior to fixed continuous positive airway pressure (CPAP) as a treatment, but it offers two advantages: faster treatment of apnea, and the potential for lower costs, according to Dr. Freedman, who is with a group practice that specializes in sleep disorders in Bannockburn, Ill., and the sleep center at Lake Forest (Ill.) Hospital.

Citing long waits for sleep studies, he said that he will put a patient on APAP pending a sleep study if the person weighs 300 pounds, snores, has had observed apnea, and is drowsy during the day. In such cases, he said, the sleep study must still be done within 30 days to secure reimbursement and to determine pressures.

Although attended APAP in a sleep laboratory is currently accepted as useful for titrating fixed CPAP pressures in uncomplicated patients, Dr. Freedman said that unattended APAP has not been established as useful for that purpose. Unattended APAP also is not established as a treatment for patients who have never used CPAP, but Dr. Freedman said this may no longer be valid.

He cited a randomized controlled trial in which 360 patients were randomized to standard CPAP, APAP titrated at home, or titration at home by a predicted formula (Am. J. Respir. Crit. Care Med. 2004;170:1218–24). Successful home titration of APAP went from 83% on the first try to 96% on the second try. All groups had equivalent improvements in quality of life, and nearly all patients wanted to continue the treatments to which they had been assigned.

Dr. Freedman listed various monikers for the new technology—automated, auto-titrating, auto-adjusting, and self-titrating—but settled on APAP as a common term. The devices vary considerably in efficacy, he advised, and their role in treating obstructive sleep apnea is not well defined.

“All APAPs are not the same,” he said, warning against generalizing conclusions from clinical studies of any one APAP technology to APAP devices as a class.

He emphasized that the devices use different detection methods, employ different algorithms, and have different response times. Notably, whereas some monitor inspiratory flow, others measure resistance.

“They all respond in different ways,” he said. “Nobody knows what the best algorithm is.”

Among the studies he cited was a benchmark testing of five APAP machines (Eur. Respir. J. 2004;24:649–58). All five suppressed obstructive apnea, but none suppressed flow limitation. The investigators reported considerable variation in residual hypopnea, control of snoring, and response to mask leaks. Four of the machines inappropriately increased pressure in response to central apnea.

Dr. Freedman suggested APAP machines that use a forced oscillation technique (FOT) may be better suited than flow-based APAP for evaluation of central apnea.

“You don't want a machine to make central apnea worse,” he said.

APAP should not be used to treat patients who hyperventilate, have heart failure or COPD/chronic lung disease, or do not snore, according to Dr. Freedman. All these conditions have been excluded from the studies performed so far.

He said the lack of data also makes APAP's efficacy unclear for obstructive sleep apneas that are related to rapid eye movement, are position dependent, involve high pressures, or occur in patients who are intolerant of CPAP.

AutoCPAP will never be superior to fixed CPAP, but it's faster and less expensive. DR. FREEDMAN

SCOTTSDALE, ARIZ. — Automatic devices that adjust continuous positive airway pressure in response to changes in airway resistance or flow are as effective as conventional machines for the treatment of uncomplicated obstructive sleep apnea, Dr. Neil S. Freedman said at a meeting on sleep medicine sponsored by the American College of Chest Physicians.

AutoCPAP (APAP) will never be superior to fixed continuous positive airway pressure (CPAP) as a treatment, but it offers two advantages: faster treatment of apnea, and the potential for lower costs, according to Dr. Freedman, who is with a group practice that specializes in sleep disorders in Bannockburn, Ill., and the sleep center at Lake Forest (Ill.) Hospital.

Citing long waits for sleep studies, he said that he will put a patient on APAP pending a sleep study if the person weighs 300 pounds, snores, has had observed apnea, and is drowsy during the day. In such cases, he said, the sleep study must still be done within 30 days to secure reimbursement and to determine pressures.

Although attended APAP in a sleep laboratory is currently accepted as useful for titrating fixed CPAP pressures in uncomplicated patients, Dr. Freedman said that unattended APAP has not been established as useful for that purpose. Unattended APAP also is not established as a treatment for patients who have never used CPAP, but Dr. Freedman said this may no longer be valid.

He cited a randomized controlled trial in which 360 patients were randomized to standard CPAP, APAP titrated at home, or titration at home by a predicted formula (Am. J. Respir. Crit. Care Med. 2004;170:1218–24). Successful home titration of APAP went from 83% on the first try to 96% on the second try. All groups had equivalent improvements in quality of life, and nearly all patients wanted to continue the treatments to which they had been assigned.

Dr. Freedman listed various monikers for the new technology—automated, auto-titrating, auto-adjusting, and self-titrating—but settled on APAP as a common term. The devices vary considerably in efficacy, he advised, and their role in treating obstructive sleep apnea is not well defined.

“All APAPs are not the same,” he said, warning against generalizing conclusions from clinical studies of any one APAP technology to APAP devices as a class.

He emphasized that the devices use different detection methods, employ different algorithms, and have different response times. Notably, whereas some monitor inspiratory flow, others measure resistance.

“They all respond in different ways,” he said. “Nobody knows what the best algorithm is.”

Among the studies he cited was a benchmark testing of five APAP machines (Eur. Respir. J. 2004;24:649–58). All five suppressed obstructive apnea, but none suppressed flow limitation. The investigators reported considerable variation in residual hypopnea, control of snoring, and response to mask leaks. Four of the machines inappropriately increased pressure in response to central apnea.

Dr. Freedman suggested APAP machines that use a forced oscillation technique (FOT) may be better suited than flow-based APAP for evaluation of central apnea.

“You don't want a machine to make central apnea worse,” he said.

APAP should not be used to treat patients who hyperventilate, have heart failure or COPD/chronic lung disease, or do not snore, according to Dr. Freedman. All these conditions have been excluded from the studies performed so far.

He said the lack of data also makes APAP's efficacy unclear for obstructive sleep apneas that are related to rapid eye movement, are position dependent, involve high pressures, or occur in patients who are intolerant of CPAP.

AutoCPAP will never be superior to fixed CPAP, but it's faster and less expensive. DR. FREEDMAN