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OSA Can Complicate Anesthesia Delivery
Respiratory Therapists and Anesthesiologists Must Be Vigilant

By Sharlene Sephton

An anesthesia mask looms over the patient undergoing surgery. The glare from the lights overhead dim, and consciousness slips away. Seduced into slumber, his upper airway muscles relax, closing off the passage. He ceases breathing.

If this was a typical night at home in bed, his brain would sense trouble and briefly awaken him to restart his breathing. But as he lies on the operating table, the anesthesia inhibits these arousals, and the amount of oxygen in his bloodstream falls dangerously low.

This scenario demonstrates the risks anesthesia presents for obstructive sleep apnea patients. "Although there have been no clinical trials on anesthesia in sleep apnea patients, clinical experience confirms that anesthesia can be problematic in these patients," according to Christin Engelhardt, executive director of the American Sleep Apnea Association (ASAA).

Yet, with meticulous preparation, careful maintenance of the airway during surgery, and postoperative vigilance, anesthesia can be delivered safely.1

Preoperative Assessment
"Not all patients are aware that they suffer from obstructive sleep apnea," says David J. Plevak, MD, associate professor of anesthesiology at the Mayo Clinic, Rochester, Minn. "It's an illness that is not completely appreciated and is underdiagnosed."

Therefore, he stresses that a patient with OSA not undergo elective procedures until a preoperative assessment, including a physical examination and previous history of anesthesia or surgery, is performed. Dr. Plevak suggests several key questions to ask patients:2

# Do you snore nightly?

# Has anyone ever said that you stop breathing in your sleep?

# Do you feel tired and groggy on awakening?

# Do you fall asleep easily during the day?

# Do you frequently have headaches in the morning? (However, this symptom is nonspecific.)

"Anesthesiologists have an important role in detecting OSA symptoms," Engelhardt agrees. "By asking patients these questions during pre-surgery screening, they will start to take their symptoms more seriously."

If sleep apnea is suspected, a sleep study may be warranted. Other specialized tests, such as an echocardiogram or pulmonary function tests, can help clarify physical findings that might suggest systemic or pulmonary hypertension, heart failure or impaired oxygenation, all of which are markers of OSA.2

Once OSA is recognized, the anesthesiologist will know to use caution when administering sedatives and maintaining proper airway control throughout the surgery.

Postoperative Considerations
This vigilance should continue into the postoperative period, Dr. Plevak says. "Certain medications that patients are given during surgery may be lingering in the immediate post-op period and exacerbate periods of apnea."

CPAP should be used in the recovery room and the pressure monitored because after anesthesia it may need to be increased. In most cases, allowing medications time to be metabolized is all that is necessary. In severe instances, continuing mechanical ventilation in recovery may be required.

"The worst case is that someone be transferred from a monitored area to an unmonitored area and they develop apnea episodes causing a medical emergency. It might lead to patient demise," Dr. Plevak says.

However, several anesthesiologists alerted the ASAA about insurance companies that have refused to allow OSA patients to be kept under the care of medical personnel where they could be monitored appropriately, according to Engelhardt. In response, the ASAA board of directors approved last year a statement on same-day surgery that reads, in part:

"Given the nature of the disorder, it may be fitting to monitor sleep apnea patients for several hours after the last dose of anesthesia and opioids or other sedatives, longer than non-sleep apnea patients require and possibly through one full natural sleep period. Hence there is concern that same-day surgery may not be appropriate for some sleep apnea surgery patients."3

The ASAA is hoping respiratory therapists and anesthesiologists will help to increase the recognition of sleep apnea among their patients by thorough screening and will take the necessary steps, including informing hospitals and third-party payors of the precarious relationship between sleep apnea and anesthesia, to provide safe delivery of anesthesia.

References
1. Ogan OU, Plevak DJ. Sleep apnea and anesthesia. WAKE-UP CALL [ASAA newsletter] 1996 Jun/July.

2. Ogan OU, Plevak DJ. Anesthesia safety is always an issue with obstructive sleep apnea. Anesthetic Patient Safety Foundation Newsletter 1997;12(2):14-15.

3. Sleep apnea and same-day surgery accessed via the Web at http://www.sleepapnea.org/resources/pubs/sameday.html.

Sharlene Sephton is editor of ADVANCE.

Sleep Tracks, Advance for Managers of Respiratory Care, June, 2000.

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SLEEP APNEA AND SAME-DAY SURGERY

It is well known that sleep apnea* can be a complicating factor in the administration of general anesthesia. It is also known that when the anesthesiologist is aware of the sleep apnea in the patient undergoing surgery and takes appropriate measures to maintain the airway, the risks of administering anesthesia to people with sleep apnea can be minimized.

Although there have been no clinical trials on anesthesia in sleep apnea patients, clinical experience confirms that anesthesia can be problematic in these patients. The cause of potential problems is seen in an anatomic and physiologic understanding of sleep apnea: the syndrome of obstructive sleep apnea is characterized by repetitive episodes of upper airway obstruction during sleep. ("Apnea" literally means "without breath" and is clinically defined as a cessation of breath that lasts at least ten seconds.) Sleep apnea may be accompanied by sleep disruption and arterial oxygen desaturation.

General anesthesia suppresses upper airway muscle activity, and it may impair breathing by allowing the airway to close. Anesthesia thus may increase the number of and duration of sleep apnea episodes and may decrease arterial oxygen saturation. Further, anesthesia inhibits arousals which would occur during sleep. Attention to sleep apnea should continue into the post-operative period because the lingering sedative and respiratory depressant effects of the anesthetic can pose difficulty, as can some analgesics.

Given the nature of the disorder, it may be fitting to monitor sleep apnea patients for several hours after the last dose of anesthesia and opioids or other sedatives, longer than non-sleep apnea patients require and possibly through one full natural sleep period. Hence there is concern that same-day surgery (also known as out-patient or ambulatory surgery) may not be appropriate for some sleep apnea surgery patients.

Before surgery, the anesthesiologist should first conduct a thorough preoperative assessment (including history of anesthesia) and physical examination. The use of preoperative sedatives must be considered carefully as sedative medication, like anesthesia, suppresses upper airway muscle activity. During surgery, maintaining the patency of the airway is the anesthesiologist's primary concern.

The period of awakening from anesthesia after surgery can also be problematic for sleep apnea patients. In patients who have undergone surgery to treat sleep apnea, the airway can be narrowed from swelling and inflammation. There may also be some upper airway swelling secondary to intubation and extubation. As mentioned, the lingering sedative and respiratory depressant effects of the anesthetic can pose difficulty. If narcotics are found to be necessary in the post-operative period, appropriate monitoring of oxygenation, ventilation, and cardiac rhythm should be provided as narcotic analgesics can precipitate or potentiate apnea that may result in a respiratory arrest. Perioperative vigilance must continue into the postoperative period.

Many patients require postoperative intubation and mechanical ventilation until fully awake. Patients who already use a prescribed CPAP (Continuous Positive Airway Pressure) machine should utilize it, but the pressure should be monitored to ascertain that it is adequate. CPAP can also be employed postoperatively in other patients without their own machine to support breathing. For certain patients, it may be judicious to admit them to an intermediate care or intensive care area postoperatively to facilitate close monitoring and airway support measures.

Therefore it is deemed wise to let sleep apnea patients remain in the care of medical personnel until it can be ascertained that their breathing will not be obstructed. While sleep apnea patients may require a longer period of time in the care of medical personnel than would otherwise be required of the surgical procedure, this precaution is prudent and enables anesthesiologists to provide safe anesthetic care for sleep apnea patients.

Approved by the ASAA Board of Directors June, 1999.

It should be remembered that the overwhelming majority of sleep apnea cases have not been identified. Thus it is not sufficient simply to ask if a patient has sleep apnea. Instead, health care professionals must ask proper screening questions of their patients, especially those individuals at risk for sleep apnea and those children undergoing a tonsillectomy and adenoidectomy, before making decisions on patient care.

For more information about sleep apnea and anesthesia, including screening questions, anesthesiologists can read "Anesthesia Safety Always an Issue with Obstructive Sleep Apnea" by Okoronkwo U. Ogan, MD and David J. Plevak, MD, Anesthetic Patient Safety Foundation Newsletter, Summer 1997 (Volume 12, No. 2, p. 14-15). Also of interest is "Sleep Apnea and Narcotic Postoperative Pain Medication: A Morbidity and Mortality Risk" by Ann Lofsky, MD, Anesthesia Patient Safety Foundation Newsletter, Summer 2002 (Volume 17, No. 2, p. 24-25). "Creation of Observational Unit May Decrease Sleep Apnea Risk", a Letter to the Editor from Jonathon Benumof, MD, appears in the Fall 2002 issue of the Anesthesia Patient Safety Foundation Newsletter (Volume 17, No. 3, p. 39). (A search of the Global Anesthesiology Network entire site, www.gasnet.org, using the term "sleep apnea," may also be beneficial.) Anesthesiologists may also find interesting the article "Perioperative Apnea Diagnosis, Management Deemed Critical" on a presentation given by Jonathon Benumof, MD at Anesthesia Update 2000.

Another interesting article is Postoperative Complications in Patients With Obstructive Sleep Apnea Syndrome Undergoing Hip or Knee Replacement: A Case-Control Study by Rakesh M. Gupta, MD, Javad Parvizi, MD, Arlen D. Hanssen, MD, and Peter C. Gay, MD. The researchers conducted a retrospective case-control study of patients having knee or hip replacement surgery and found that, compared to the controls, complications were significantly higher in the sleep apnea group. Further, they found that there was a trend for the untreated OSA patients to have more complications than the treated OSA patients. (Complications were defined as reintubation, acute hypercapnia, episodic desats, arrhythmia, myocardial ischemia or infarction, and delirium.)

A source of information for the general public is the article "Sleep Apnea and Anesthesia" from the June-July 1996 issue of the ASAA newsletter WAKE-UP CALL.

*There are three types of sleep apnea: obstructive, central, and mixed (a combination of the two). Obstructive sleep apnea is the most common. Patients with mixed sleep apnea should be treated as if they had obstructive. Pure central sleep apnea, while rare, also requires consideration.