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Severe sleep apnea may raise postoperative cardiovascular complication risk

Unrecognized severe obstructive sleep apnea is associated with a significantly increased risk for cardiovascular complications within 30 days after surgery, according to new data published in JAMA.

Among 1,218 patients included in the analysis, the primary composite outcome — myocardial injury, cardiac death, heart failure, thromboembolism, atrial fibrillation and stroke — occurred in 19.3% of all patients within 30 days after major noncardiac surgery.

The rate of the primary outcome was higher in patients with obstructive sleep apnea, occurring in 30.1% of patients with severe obstructive sleep apnea, 22.1% of patients with moderate obstructive sleep apnea, 19% of patients with mild obstructive sleep apnea and 14.2% of patients without obstructive sleep apnea.

Further, results linked obstructive sleep apnea to an increased risk for the primary outcome (adjusted HR = 1.49; 95% CI, 1.19-2.01). When assessed according to disease severity, however, this association was significant only for patients with severe obstructive sleep apnea (aHR = 2.23; 95% CI, 1.49-3.34) and not for those with moderate (aHR = 1.47; 95% CI, 0.98-2.09) or mild obstructive sleep apnea (aHR = 1.36; 95% CI, 0.97-1.91).

Additional findings

In post hoc analyses, there were associations between severe obstructive sleep apnea and cardiac death (aHR = 13.66; 95% CI, 1.63-114.19), myocardial injury (aHR = 1.8; 95% CI, 1.17-2.77), congestive heart failure (aHR = 6.55; 95% CI, 1.71-25.06) and atrial fibrillation (aHR = 3.96; 95% CI, 1.24-12.6). Severe disease remained independently associated with cardiovascular complications in a sensitivity analysis that substituted myocardial infarction for myocardial injury.

Using a high-resolution pulse oximeter wristwatch (PULSOX-300i, Konica Minolta Sensing Inc.), the researchers monitored oxyhemoglobin desaturation. Data showed that patients with vs. without cardiovascular complications had longer mean cumulative duration of oxygen hemoglobin desaturation less than 80% during the first 3 nights after surgery (23.1 vs. 10.2 minutes; P < .001).

Perioperative outcomes appeared to be unaffected by type of anesthesia, use of postoperative opioids and supplemental oxygen therapy.

The researchers also preoperatively assessed risk for sleep apnea using the STOP-Bang questionnaire. They found that high risk was linked to an increased rate of the primary outcome (aHR = 1.68; 95% CI, 1.11-2.54), myocardial injury and ICU readmission. Intermediate risk was associated with ICU readmission and wound infection.

Sleep apnea as a risk factor

The multicenter, prospective POSA study included at-risk adults without a diagnosis of sleep apnea undergoing major noncardiac surgery at eight hospitals in five countries from 2012 to 2017. The mean age of the patients was 67 years and 40.2% were women.

Patients were diagnosed with obstructive sleep apnea based on a preoperative overnight sleep study using a portable type 3 sleep monitoring device (ApneaLink Plus, ResMed). Among all patients, 67.6% had unrecognized obstructive sleep apnea.

The researchers noted that the study had limitations, including a lack of electroencephalograms recorded in the preoperative sleep studies and a lack of control in perioperative management. The study is also not generalizable to ambulatory or minor procedures or to a broader population, as 54.7% of the patients were Chinese.

However, the study also has important strong points, according to Dennis Auckley, MD, from MetroHealth Medical Center, Case Western Reserve University, and Stavros Memtsoudis, MD, PhD, MBA, from Weill Cornell Medical College and Hospital for Special Surgery.

“This study has several strengths that distinguish it from previous work in the field: The study is large, prospective and well-organized; has predefined outcomes; and uses rigorous methodology and follow-up,” they wrote in an accompanying editorial.

For instance, Auckley and Memtsoudis also highlighted the use of a standardized objective sleep testing using a portable type 3 testing device as being more accurate than questionnaire screening, noting that it is now also viewed as a reasonable alternative to polysomnography. The use of clinically relevant predetermined outcomes that showed that an association not only between severe obstructive sleep apnea and the primary composite outcome but between severe disease and the individual components as well was also important.

The researchers also “avoided the pitfall often seen in the perioperative literature of assigning postoperative oxygen desaturation as an outcome,” and instead only focused on clinical events, Auckley and Memtsoudis wrote.

Follow-up was excellent, as was controlling for most confounders, although more information on opioid dosing would have been helpful, they added.

Importantly, the study raises awareness that obstructive sleep apnea is a major perioperative risk factor that warrants attention.

“Although more research is needed to further detail the mechanisms and clinical management strategies, [obstructive sleep apnea] as a disease complex should receive the same attention as other comorbidities, such as diabetes, for which optimization has improved perioperative morbidity and mortality over recent decades,” they wrote. – by Melissa Foster

Disclosures: ResMed has supplied the ApneaLink devices and PULSOX-300i oximeter wristwatch in all sites as an unrestricted loan. These were returned at the end of the study. One author reports she has received grants from the Ontario Ministry of Health and Long-Term Care, Acacia Pharma and Medtronic and she is holding a patent pending for the STOP-Bang questionnaire. All other authors report no relevant financial disclosures. Auckley reports he has received research funding from Medtronic. Memtsoudis reports he has received personal fees from Teikoku and Sandoz.