Study finds that identification and treatment of unrecognized obstructive sleep apnea before surgery improves outcomes
Patient reports better quality of life from treatment
(September 18, 2013)
An estimated 80 percent of patients who have obstructive sleep apnea (OSA) go undiagnosed, including Deanna G. McNeil, a 72-year-old nurse from Toronto. Before hip replacement surgery in 2010, Deanna completed the STOP-Bang questionnaire, created by Frances Chung, M.B.B.S., professor, Department of Anesthesia, University of Toronto, Ontario. Based on the questionnaire, Deanna was suspected to have OSA.
OSA is a serious sleep disorder in which breathing stops and starts during sleep. It is often associated with other health conditions such as arrhythmia, hypertension, heart failure and diabetes. Also these patients are more prone to having motor vehicle accidents while driving. Patients with OSA are at an increased risk during surgery and anesthesia, particularly for respiratory depression when opioids are given for postoperative pain management.
“Since physician anesthesiologists function as perioperative physicians before, during and after surgery, it is important we help identify patients with OSA,” said Dr. Chung. “In the preoperative clinic, we evaluate and educate patients regarding anesthesia. As airway experts, this is a great opportune time to treat patients for OSA.”
After a sleep study, Deanna was diagnosed with OSA. She began using the mainstay treatment for the condition, continuous positive airway pressure (CPAP). During CPAP, a machine uses mild air pressure to keep airways open. A special type of CPAP, auto-titrated CPAP (APAP), adjusts delivered pressure over the course of the night automatically based on breath-by-breath measurement.
In an effort to better treat patients such as Deanna and determine the effectiveness of APAP, researchers at the University of Toronto examined 177 patients with an apnea-hypopnea index of more than 15 events per hour in a randomized controlled trial, the results of which were published in the October 2013 issue of Anesthesiology.
Eighty-seven participants received APAP for two to three nights before surgery and five nights after surgery, while 90 participants received routine care. One hundred patients completed the study. Patients who received APAP did so for 2.4 to 4.6 hours per night.
Postoperatively, patients who received APAP did better. Participants who received APAP had a median apnea-hypopnea index of three events per hour on the third postoperative night, while control patients had a median of 32 events per hour. Patients who received CPAP also had better oxygenation in the postoperative nights. Similarly, Deanna had positive outcomes after using APAP. Today, she feels much more alert as her afternoon tiredness has subsided.
Researchers hope the findings will encourage patients with OSA to use APAP, especially since daily
compliance with the machine can be low. “Some patients are concerned that the machine will be
uncomfortable. However, many adjust quickly and find its benefits very rewarding, especially in reducing
depression and motor vehicle accidents due to troublesome sleep,” noted Dr. Chung.
“Unless you get tested for OSA, you are not aware you have it,” said Deanna. “I believe APAP has given
me the opportunity to have a better quality of life. It is important for individuals to determine whether
or not they have OSA in order to address any related underlying health conditions that can impact life
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