Mayo investigators reported back in 2001 that people with obstructive sleep apnea had a higher rate of perioperative complications including hypoxia and longer lengths of stay. Since then, there have been other signals that this is a real phenomenon, but perhaps surprisingly, the evidence hasn’t exactly piled up to unequivocally prove the intuitive point.
That’s because the studies are (by necessity) case-control designs, and there are so few “real” controls — folks who’ve actually had a polysomnogram and been shown not to have OSA, as Roop Kaw et al point out in the February issue of CHEST. They remedied that problem by whacking it with big numbers, further strengthening the link between OSA and postoperative complications.
What They Did:
Using a database of almost 40,000 people who underwent preoperative evaluation by internal medicine for noncardiac surgery, they found 471 patients who had undergone polysomnogram, including 282 with obstructive sleep apnea (AHI >= 5, “cases”) and 189 without OSA (AHI < 5, “controls”).
What They Found:
Those with OSA had a higher rate of hypoxia postop (odds ratio 7.9); complications in general (OR 6.9); transfer to an ICU (OR 4.43); and longer hospital length of stay (much weaker, an unimpressive OR 1.65).
Postop hypoxemia is not necessarily a big deal (these patients can be hypoxic during a nap, right?). But the complications here seeemed real: about half required transfer to an ICU. Respiratory failure accounted for more than one-third of the complications.
Clinical Takeaway: Of course, astute physicians who’ve been watching people with OSA desaturate and go to ICUs for the past decade or more weren’t waiting for this paper to prove that OSA leads to perioperative complications. The American Society of Anesthesiologists has had a guideline document out since 2006 to help manage these patients. That document, and other experts, recommend for patients with known OSA or at high risk for undiagnosed OSA who are undergoing surgery:
- Reducing systemic opioids as much as possible (instead, use regional analgesia; neuraxial analgesia; NSAIDs);
- Observe them in PACU for longer postop — 3 hours has been suggested;
- Place them on continuous pulse oximetry postop, and provide continuous supplemental oxygen after surgery, even if they’re not hypoxemic yet;
- Put them in the lateral (side) position, not supine (on their backs) postop, if possible;
- Start CPAP if they were on it at home; if they weren’t, consider starting it in the hospital.
Kaw R et al. Postoperative Complications in Patients With Obstructive Sleep Apnea. CHEST 2012;141:436-441.