SAFE OUTCOME Sleep apnea, which is often undiagnosed, increases a patient's anesthetic risk.

As a nurse anesthetist who works in a variety of surgical settings, from office-based suites to trauma hospitals, I can expect to encounter at least one patient with obstructive sleep apnea (OSA) almost every day — either diagnosed or undiagnosed. Interestingly, up to 85% of people with OSA are undiagnosed, and research indicates that up to 30% of patients undergoing routine endoscopy either have OSA or are at a high risk for a positive screen. I consider properly handling OSA one of my top priorities. Here's my 5-point plan designed to make sure OSA patients have a safe and uneventful perioperative experience.

1. Know your patient
The syndrome of OSA is characterized by repetitive episodes of upper airway obstruction during sleep. The word "apnea" is a Greek word that literally means "without breath" and it is clinically defined as a cessation of breath that lasts at least 10 seconds despite continuing ventilatory effort. The adult human is one of the only animals to be at risk for OSA, because our upper airway is a long, soft-walled tube with no bony support. Instead of bones, we rely on the actions of muscles to keep the airway open. However, when we sleep we lose muscle tone, and the deeper the sleep the greater the muscle relaxation, regardless whether the sleep is due to natural causes or pharmacologically induced. In general, the normal, healthy person doesn't have a problem with OSA, but there are a number of things that can put a person at greater risk. Obesity (BMI greater than 30) is the leading cause of OSA in the United States (70-90% of patients with OSA are obese). Other causes include a large tongue, a small and receding mandible, enlarged tonsils, nasal obstruction, and a thick or fat neck.

2. Know the risks of OSA associated with surgery
Is your staff aware of the potential complications that can occur due to improper management of patients with OSA? Catastrophic respiratory outcomes of patients with OSA during the perioperative period have been increasing and are a very serious issue. This is most likely explained by the increase in obesity among the U.S. general population. Brain damage and death in an OSA patient are due to failure to secure the airway during the induction of anesthesia, respiratory obstruction shortly after extubation, and respiratory arrest after the administration of opioids and/or sedation to extubated patients in the recovery area.

3. Know how to properly screen your patients for OSA
Commit a thorough pre-operative review of all patients to determine whether a patient has OSA and to what severity it is. You should review all medical records, physical examinations, sleep studies and any X-rays. Even if you do a thorough pre-op review of a patient, the majority of patients with OSA will lack a formal diagnosis. The gold-standard for the diagnosis of OSA is polysomnography (PSG). How-ever, PSG is fairly expensive and there can be a wait time anywhere from 2-10 months, making it unlikely that most outpatients will have had a PSG done.

Anesthesia providers can use the STOP-Bang Questionnaire to screen patients for sleep apnea risk factors and severity, and to develop a care plan that will lead to a safe anesthetic outcome. STOP-Bang asks patients to self-report things like snoring, apneic episodes and daytime somnolence, as well as physical characteristics such as BMI and neck circumference, gender, age and airway anomalies. I've often found that many of my patients don't realize whether they snore or if they have apneic episodes, so I'll ask their partners or family members that are present — many times you will get a very enthusiastic yes from their loved ones. Flag patients who you determine to be at high risk so that you can make the appropriate modifications both intraoperatively and post-operatively.

SCREENING TOOL The STOP-Bang questionnaire is a widely used screening tool for obstructive sleep apnea (stopbang.ca).

STOP-BANG QUESTIONNAIRE
How to Identify Sleep Apnea Risk Factors

Developed in 2008 by Frances Chung, MBBS, LMCC, FRCPC, a professor of anesthesia at the University of Toronto, as a pre-surgery screening tool, the STOP-Bang questionnaire is used to help identify sleep apnea easily with 8 short questions.

STOP

Snoring

Do you snore loudly (loud enough to be heard through closed doors or your bed-partner elbows you for snoring at night)?

(Y/N)

Tired?

Do you often feel tired, fatigued or sleepy during the daytime (such as falling asleep during driving or talking to someone)?

(Y/N)

Observed?

Has anyone observed you stop breathing or choking/gasping during your sleep?

(Y/N)

Pressure?

Do you have or are you being treated for high blood pressure?

(Y/N)

BANG

Body mass index?

Body mass index more than 35 kg/m2?

(Y/N)

Age

Age older than 50?

(Y/N)

Neck size large? (measured around Adams apple)

For male, is your shirt collar 17 inches / 43cm or larger?For female, is your shirt collar 16 inches / 41cm or larger?

(Y/N)

Gender

Male?

(Y/N)

Yes to ??? 3 questions = high risk of obstructive sleep apnea

Yes to < 3 questions = low risk of obstructive sleep apnea

4. Your intraoperative game plan
The key to your intraoperative game plan is avoiding IV and volatile anesthetics whenever possible or otherwise using them sparingly. Almost all IV and volatile anesthetics are muscle relaxants and respiratory depressants. If a general anesthetic is required, try to use shorter-acting anesthetic agents and agents that are metabolized quickly. In general, I have found that patients with OSA tend to require less narcotic compared with the general population. It would be wise to consider remifentanil, which is metabolized quickly by esterases in the blood and tissues, instead of fentanyl, morphine or hydromorphone, which are metabolized much slower and can accumulate in adipose tissue. Both dexmedetomidine and ketamine are great adjuncts, because they're good sedatives and cause very little respiratory depression. Additionally, IV NSAIDs, acetaminophen and ketorolac are excellent for treating pain without any respiratory depression.

Desflurane is a better choice than both sevoflurane and isoflurane if a volatile anesthetic must be used. Desflurane provides faster wash-in and wash-out than sevoflurane or isoflurane in obese patients, and recovery is much faster after desflurane administration. If you're going to use muscle relaxants, make sure the patient has been fully reversed before extubating. I would recommend sugammadex over neostigmine because it's a more rapid-acting and reliable antagonist of residual muscle paralysis. The patient should have adequate tidal volume and respiratory rate along with intact airway reflexes and acceptable concentrations of end-tidal CO₂.

When and where it is appropriate, I strongly recommend a regional anesthetic technique instead of or along with general anesthesia. Besides regional anesthesia, early administration of local anesthetic can seriously cut down on the amount of respiratory depressing anesthetic drugs.

5. Post-op care of your OSA patients
If patients have been identified as having OSA and have a CPAP machine, they should be told to bring it with them on the day of surgery, and it should be used post-operatively until it is deemed appropriate to discontinue. Keep positive airway pressure (PAP) machines in stock for use post-operatively in undiagnosed OSA patients or OSA patients that don't bring their CPAP machines with them.

While administering analgesics, post-operative staff should be vigilant to observe for bradypnea, apnea, inability to wean from oxygen, and low or decreasing arterial oxygen saturations. If a patient has no respiratory events in PACU, the American Society of Anesthesia guidelines recommend he stays in recovery for a minimum of 3 hours. If there are any observed respiratory events, the guidelines recommend a minimum of 7 hours in the PACU. Ultimately, the decision of whether to discharge patients is up to the practitioner and should be based on the type of procedure, the type of anesthesia, the level of pain, their age and what kind of care they'll be receiving at home. In the case that respiratory events don't resolve, you may want to consider admitting the patient to the hospital with continuous SpO₂ and end tidal CO₂ monitoring. Any patient who's screened as high-risk for OSA should have follow-up and referral to have formal polysomnography and receive a formal diagnosis. OSM