Keeping an eye—and ear—out for sleep apnea

Ignoring sleep apnea is done at the patient's peril.


“For as loudly as [people with sleep apnea] snore, it's very often a forgotten disease in the hospital,” said Nick Fitterman, FACP, chief of staff and director of hospitalist services at Huntington Hospital in Huntington, N.Y.

Yet ignoring apnea is done at the patient's peril. “Sleep apnea seems to be flying under people's radar screen,” said Walter Kraft, FACP, associate professor of medicine and pharmacology at Thomas Jefferson University in Philadelphia. “It's associated with much worse outcomes than you would otherwise anticipate in the perioperative period.”

A spouse who complains about snoring is a potential indicator of sleep apnea Photo by Thinkstock
A spouse who complains about snoring is a potential indicator of sleep apnea. Photo by Thinkstock.

Surgical patients with untreated obstructive sleep apnea (OSA) are more likely to become hypoxic and develop arrhythmias postoperatively, Dr. Fitterman said. They also may be difficult to extubate and suffer pulmonary complications, he said. OSA-related problems extend beyond the surgical realm, as well. Patients with sleep apnea are more vulnerable to the respiratory effects of opioids, sedative-hypnotics and even muscle relaxants, said Lawrence Epstein, MD, associate physician in the division of sleep medicine at Brigham and Women's Hospital in Boston and chief medical officer of Sleep HealthCenters.

A hospitalist who diagnoses a previously unrecognized case of sleep apnea can potentially save a patient from unnecessary testing and invasive procedures, he added. For example, a patient with undiagnosed OSA may end up scheduled for a cardiac catheterization due to apparent syncope spells that are really the person falling asleep, Dr. Epstein said.

Over the long term, untreated OSA can impact control of hypertension and diabetes, and patients with the condition are at increased risk for falling asleep at the wheel due to sleep deprivation, Dr. Epstein added.

Hospitalists, who are in a position to notice the signs of sleep apnea, can play a critical role in diagnosing the disease and ensuring the patient gets appropriate treatment.

Assessment

As a first step in screening for sleep apnea, simply ask patients during the history if they are already on CPAP or have ever been on it, advised Howard Marcus, FACP, an internist in Austin, Texas who has written on the effect of opioids on respiration. “There are various ways to get into the diagnosis even when you only have a few minutes,” he said.

Sometimes a patient's symptoms and risk factors are obvious: If the spouse of a 250-pound patient (usually male) says the person “snores like a freight train” and stops breathing off and on throughout the night, and the patient complains of daytime fatigue, you can be pretty sure you're looking at a case of OSA, Dr. Marcus said. (It's a myth, however, that only overweight people have OSA, Dr. Fitterman noted.)

A number of questionnaires are available to screen people for OSA. One is the STOP-BANG, which assesses Snoring, Tiredness during the day, Observed apnea, high blood Pressure, Body mass index (35 or higher), Age (older than 50), Neck circumference (over 40 cm), and Gender (male). In evaluating the STOP-BANG, Dr. Kraft and colleagues found that elective surgical patients who scored as high risk for OSA had more than a ten-fold increase in the odds of postoperative complications, usually respiratory in nature. Their results were published in the October 2010 Archives of Otolaryngology Head and Neck Surgery.

“A positive STOP-BANG screening questionnaire [three yes answers] does not make a diagnosis of OSA, but it does identify patients at higher risk for the condition,” said Dr. Kraft. “It also has a very good negative predictive value for those with two or fewer positive responses, and thus seems a good tool for risk stratification.”

Treatment

Definitively diagnosing OSA requires using the “gold standard” of a polysomnography (PSG), said Tajender Vasu, MD, lead author of the STOP-BANG study and a sleep medicine fellow at Thomas Jefferson University Hospital in Philadelphia. PSG typically isn't done in the hospital, however, so hospitalists can use portable sleep monitors if they suspect OSA, Dr. Epstein said. The portable monitors can be sufficient to guide treatment during hospitalization in patients without comorbid respiratory or cardiac disorders that interfere with the accuracy of the devices. Then patients can be referred for more extensive sleep studies after discharge, Dr. Epstein said.

A continuous positive airway pressure (CPAP) machine is typically used to manage suspected OSA during hospitalization, experts said. Beth Israel Deaconess Medical Center (BIDMC) in Boston keeps careful tabs on postoperative patients who had high-risk preoperative scores on the STOP-BANG, then gives CPAP if needed, said Suzanne Bertisch, MD, a sleep medicine specialist and former hospitalist there.

“We are presumptively treating [patients] as if they have OSA, without being formally diagnosed with a sleep study,” Dr. Bertisch said. “Those with apneas and desaturations in the [post-anesthesia recovery unit] following surgery are given CPAP in the hospital and are loaned a machine to take home.”

Ideally, patients with previously diagnosed OSA would bring their CPAP machine with them to use during hospitalization, said Adebola Adesanya, MD, a hospitalist and anesthesiologist at the University of Texas Southwestern Medical Center in Dallas. “It is very helpful if the surgeon or anesthesiologist involved with the surgery is aware of the machine settings prior to the surgery,” he said.

Hospital patients who appear to have OSA also can benefit from using AutoPAP machines—i.e., CPAP machines that alter the pressure of air delivered to meet changing patient needs, Dr. Adesanya said. He co-authored an article in the December 2010 Chest that included an algorithm for managing surgical patients diagnosed with, or at high risk for, OSA. Strategies include using wrist or armband alerts to flag at-risk patients, and continuously monitoring oxygen saturation in the postoperative period. While based on current evidence, the algorithm hasn't been validated in a study, Dr. Adesanya noted.

Simple strategies can also reduce risk in the postoperative phase, Dr. Kraft noted. “Lateral positioning may help reduce [airway] obstruction,” he said.

Occasionally, inpatients at BIDMC undergo sleep studies when OSA is believed to be complicating their disease, in order to learn how to best approach treatment, Dr. Bertisch said. Candidates for a study might include patients who have “hypercarbic failure with obesity hypoventilation syndrome and OSA,” she said.

Some patients will have both OSA and central sleep apnea, noted Dr. Adesanya. In central sleep apnea, the problem is the brain's initiation of breathing; OSA involves a physical barrier. While a sleep study is needed to distinguish between the two, hospitalists should have a “high index of suspicion” for central sleep apnea when caring for patients with severe heart failure and other predisposing conditions, such as renal failure or a recent stroke, he said.

Oximetry and capnography can detect hypoxia and increased CO2 levels non-invasively in central sleep apnea patients, as can arterial blood gasses. As for treatment, theophylline and acetazolamide have been tried; bilevel positive airway pressure also may be useful for patients with hypercapnia, said Dr. Adesanya. In any case, hospitalists should order an outpatient sleep study if central sleep apnea is suspected, he said.

Respiratory depression

Hospitalists can help patients with diagnosed or suspected sleep apnea sidestep the threat of medication-related respiratory problems, experts noted. “Oftentimes, patients with OSA are on benzodiazepines and sleep aids, with polypharmacy all over the place. But the real killer is the narcotic,” said Dr. Marcus.

Physicians should weigh the risks and benefits of ordering narcotics for patients with diagnosed or probable OSA and strive to use the lowest effective dose, Dr. Fitterman said. Prescribers are often “heavy-handed with dosing” for patients who are obese and may be at risk for OSA, he added.

Dr. Adesanya recommended the sedative analgesic dexmedetomidine be considered for pain management, since it doesn't cause as much respiratory depression as opioids in recommended doses. The drug is also known to cause minimal airway compromise even in people with sleep apnea, he said. When appropriate, patients with sleep apnea or at high risk for it should receive regional analgesia, which might eliminate their need for opiates entirely, he added.

Detecting patients headed toward respiratory depression as early as possible requires monitoring end-tidal CO2, which tells you the person is hypoventilating, Dr. Adesanya said. By contrast, he noted, hypoxia detected by oximetry is a late sign of respiratory depression.

You can monitor for CO2 noninvasively with capnography, which most operating rooms use, Dr. Adensanya added. While capnography isn't usually continued in the recovery room, it could be, especially for high-risk patients, he said. Increased collaboration between anesthesiologists and hospitalists on issues like this would be useful in managing patients with OSA, he said.

At discharge, hospitalists should advise patients who are at risk for sleep apnea to follow up with their primary care physician for formal diagnosis, Dr. Kraft said. They should also ask patients whether they take sleep medications or drink alcohol near bedtime, either of which can exacerbate OSA, Dr. Fitterman said, adding that some patients self-medicate for sleep disorders. Obese patients should be counseled about weight loss, as well, experts said.

Future research

Studies to date have generally shown nasal CPAP reduces postoperative complications in people undergoing abdominal and cardiac surgery, Dr. Vasu said. Still, there is a need for a randomized controlled trial of perioperative nasal CPAP in patients identified as likely to have OSA, he said.

BIDMC is collecting data to look at the impact of its screening program and proactive treatment for surgical patients with potential OSA, Dr. Bertisch said. While logically it makes sense that the hospital's approach would improve outcomes, the costs versus benefits aren't known at this point, and there is no longitudinal data to support the approach, she said.

“The argument is that ‘it only takes one death’, but on the other hand, we don't know what the true risks or costs are,” Dr. Bertisch said.

Also unclear is whether CPAP improves outcomes in OSA patients taking narcotics, said Dr. Marcus; this needs to be a focus of future research.

One thing appears likely: OSA will become increasingly commonplace as the population continues to get more overweight, Dr. Epstein said. OSA is something “we're going to encounter more and more—and we need greater awareness of it,” he said.