Clinical question: Are patients with obstructive sleep apnea (OSA) and preoperative hypercapnia more likely to experience postoperative complications than those without?
Background: Obesity hypoventilation syndrome (OHS) is known to increase medical morbidity in patients with OSA, but its impact on postoperative outcome is unknown.
Study design: Retrospective cohort study.
Setting: Single tertiary-care center.
Synopsis: The study examined 1,800 patients with body mass index (BMI) ≥30 who underwent polysomnography, elective non-cardiac surgery (NCS), and had a blood gas performed. Of those, 194 patients were identified as having OSA with hypercapnia, and 325 were identified as having only OSA. Investigators found that the presence of hypercapnia in patients with OSA, whether from OHS, COPD, or another cause, was associated with worse postoperative outcomes. They found a statistically significant increase in postoperative respiratory failure (21% versus 2%), heart failure (8% versus 0%), tracheostomy (2% versus 1%), and ICU transfer (21% versus 6%). Mortality data did not reach significance.
The major limitation to the study is that hypercapnia is underrecognized in this patient population, and as a result, only patients who had a blood gas were included; many hypercapnic patients may have had elective NCS without receiving a blood gas and were thus excluded.
Bottom line: Consider performing a preoperative blood gas in patients with OSA undergoing elective NCS to help with postoperative complication risk assessment.
Citation: Kaw R, Bhateja P, Paz y Mar H, et al. Postoperative complications in patients with unrecognized obesity hypoventilation syndrome undergoing elective noncardiac surgery. Chest. 2016;149(1):84-91 doi:10.1378/chest.14-3216.
