If you don’t have a standardized process for obstructive sleep apnea screening of all patients heading into the operating room at your hospital you should, because perioperative pulmonary complications can occur, according to Efren C. Manjarrez MD, SFHM, FACP.
Dr. Efren C. Manjarrez
If OSA is not documented in the patient’s chart, you may find yourself making a bedside assessment. “I usually don’t ask the patients this because they can’t necessarily answer the questions,” Dr. Manjarrez, associate professor in the division of hospital medicine at the University of Miami, said at SHM Converge, the annual conference of the Society of Hospital Medicine. “So, I ask their partner: ‘Does your partner snore loudly? Are they sleepy during the daytime, or are they gasping or choking in the middle of the night?’”
The following factors have a relatively high specificity for OSA: a STOP-Bang score of 5 or greater, a STOP-Bang score of 2 or greater plus male gender, and a STOP-Bang score of 2 or greater plus a body mass index greater than 35 kg/m2. Clinicians can also check the Mallampati score on their patients by having them tilt their heads back and stick out their tongues.
“If the uvula is not touching the tongue, that’s a Mallampati score of 1; that’s a pretty wide-open airway,” Dr. Manjarrez said. “However, when you do not have any form of an airway and the palate is touching the tongue, that is a Mallampati score of 4, which indicates OSA.”
Other objective data suggestive of OSA include high blood pressure, a BMI over 35 kg/m2, a neck circumference of greater than 40 cm, and male gender. In a study of patients who presented for surgery who did not have a diagnosis of sleep apnea, a high STOP-Bang score indicated a high probability of moderate to severe sleep apnea (Br J. Anaesth 2012;108[5]:768-75).
“If the STOP-Bang score is 0-2, your workup stops,” Dr. Manjarrez said. “If your STOP-Bang score is 5 or above, there’s a high likelihood they have moderate or severe sleep apnea. Patients who have a STOP-Bang of 3-4, calculate their STOP score. If the STOP score is 2 or more and they’re male, obese, and have a neck circumference of greater than 40 cm, there’s a pretty good chance they’ve got OSA.”
Screening for OSA prior to surgery matters, because the potential pulmonary complications are fairly high, “anywhere from postoperative respiratory failure to COPD exacerbation and hypoxia to pneumonia,” he continued. “These patients very commonly desaturate and are difficult for the anesthesiologists to intubate. Fortunately, we have not found significant cardiac complications in the medical literature, but we do know that patients with OSA commonly get postoperative atrial fibrillation. There are also combined complications like desaturation and AFib and difficult intubations. Patients with sleep apnea do have a higher resource utilization perioperatively. Fortunately, at this point in time the data does not show that patients with OSA going in for surgery have an increased mortality.”
To optimize the care of these patients prior to surgery, Dr. Manjarrez recommends that hospitalists document that a patient either has known OSA or suspected OSA. “If possible, obtain their sleep study results and recommended PAP settings,” he said. “Ask patients to bring their PAP device to the hospital or to assure the hospital has appropriate surrogate devices available. You also want to advise the patient and the perioperative care team of the increased risk of complications in patients at high risk for OSA and optimize other conditions that may impair cardiorespiratory function.”
Perioperative risk reduction strategies include planning for difficult intubation and mask ventilation, using regional anesthesia and analgesia, using sedatives with caution, minimizing the use of opioids and anticipating variable opioid responses. “When I have a patient with suspected sleep apnea and no red flags I write down ‘OSA precautions,’ in the chart, which means elevate the head of the bed, perform continuous pulse oximetry, and cautiously supply supplemental oxygen as needed,” he said.
Postoperatively, he continued, minimize sedative agents and opioids, use regional and nonopioid analgesics when possible, provide supplemental oxygen until the patient is able to maintain baseline SaO2 on room air in a monitored setting, maintain the patient in nonsupine position when feasible, and continuously monitor pulse oximetry.
Consider delay of elective surgery and referral to a sleep medicine specialist in cases of uncontrolled systemic conditions or impaired gas exchange, including hypoventilation syndromes (a clue being a serum HC03 of 28 or higher), severe pulmonary hypertension (a clue being right ventricular systolic blood pressure or pulmonary systolic pressure of 70 mm Hg or above, or right ventricular dilatation/dysfunction), and hypoxemia not explained by cardiac disease.
A systematic review and meta-analysis of six studies that included 904 patients with sleep apnea found that there was no significant difference in the postoperative adverse events between CPAP and no-CPAP treatment (Anesth Analg 2015;120:1013-23). However, there was a significant reduction in the Apnea-Hypopnea Index postoperatively among those who used CPAP (37 vs. 12 events per hour; P less than .001), as well as a significant reduction in hospital length of stay 4 vs. 4.4 days; P = .05).
Dr. Manjarrez reported having no financial disclosures.
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