Due to an aging population, higher rates of obesity and an increase in the overall number of surgical procedures, more surgical patients are likely to present with obstructive sleep apnea (OSA).
To address the challenges that anesthesiologists face perioperatively while managing patients with OSA, the Society of Anesthesia and Sleep Medicine (SASM) released new practice guidelines in Anesthesia & Analgesia (2016;123:452-473).
“OSA patients pose a two- to threefold risk of cardiac and pulmonary complications compared to a normal patient without OSA,” said Frances Chung, MBBS, FRCPC, chair of the SASM Preoperative Assessment Task Force, which reviewed 61 published, peer-reviewed articles consisting of 413,304 OSA patients and 8,556,279 non-OSA patients. All these articles showed an increased risk for complications from OSA with surgery. “This is the reason why we developed the guideline,” said Dr. Chung, who also is professor of anesthesiology and pain medicine at University Health Network, University of Toronto, and immediate past president of SASM.
This is an essential guideline for anesthesiologists to use during preoperative screening assessment and preparation of patients with known and unknown OSA, as well as treated and untreated OSA.
Dr. Chung said it is important that anesthesiologists be aware of suspected OSA patients and patients who are nonadherent to continuous positive airway pressure (CPAP) therapy. “Patients with suspected OSA and those who are not treated may receive opioids during and after surgery, which may cause issues,” she said.
The guideline recommends that patients fill out the short updated STOP-Bang sleep apnea questionnaire to identify suspected OSA (Figure). “This screening tool identifies, with reasonable accuracy, OSA cases,” Dr. Chung said. “We also advocate that a family doctor and/or surgeon attempt to identify patients who may have suspected OSA earlier in the process.”
The guidelines state that although a diagnosis of OSA may change postoperative outcomes, there is not enough evidence to support delaying or canceling surgery, with a few exceptions. Patients with obesity hypoventilation syndrome, severe pulmonary hypertension or resting hypoxemia may warrant further evaluation, including perhaps treatment, such as with CPAP. In these patients, further optimization is necessary to prevent postoperative complications (Table 1).
If available, it may be prudent to have the results of a sleep study and the patient’s recommended PAP setting before undergoing surgery. Similarly, if feasible, facilities may want to invest in PAP equipment for perioperative use or have patients bring their own PAP equipment to the surgery location.
“There is preliminary evidence that CPAP may provide some benefits to patients in the perioperative period,” Dr. Chung said. “For patients who are already on CPAP, we recommend that the therapy continue after surgery.” Setting adjustments may be required, however, for facial swelling, upper airway edema, fluid shifts, pharmacotherapy and respiratory function.
“Patients who are not adherent to CPAP need to be watched, and may require further monitoring or CPAP in the post-op period,” Dr. Chung said (Table 2).
Because opioids may cause respiratory depression and impair the arousal response in OSA patients, anesthesiologists should adjust or titrate pain medication according to the needs of an individual patient, Dr. Chung said. “These patients may need postoperative monitoring.”
Furthermore, to better manage OSA patients overall, “there needs to be a collaborative effort among the surgeon, the family doctor, the patient and the anesthesiologist,” Dr. Chung said.
Unlike some of the previous practice guidelines, “ours is based on the most recent evidence, easy to implement and more cost-effective,” Dr. Chung said. However, further research is needed to delineate how best to risk-stratify OSA patients and how to optimize the preoperative assessment and preparation of patients with known and unknown, and treated and untreated, OSA.