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Preoperative Evaluation/Patient Issues/Obesity & sleep apnea

QUESTION:

I am being besieged by the morbidly obese with diagnosed or suspected sleep apnea .  I am familiar with Dr. Benumof's ASA Refresher Course article and several letters to the editor.  I am also aware that this subject will be discussed at the upcoming SAMBA meeting.  I am having difficulty putting together a policy re: sleep apnea. Does anyone have anything that might help me?

-- From S.R., Dallas, TX

REPLY:

Unfortunately there is very little data available which helps us develop evidence-based protocols for the management of OSA patients. The vast majority of published information is either retrospective reviews, case reports, or opinion. We do know that the number of patients with OSA is expected to increase 5-10 fold over the next decade so this problem is not going away. It is estimated that 4% of middle-aged males and 2% of females have OSA and 80-90% of patients have not been diagnosed.

Patients with OSA are at increased risk for perioperative problems including difficult intubation, postoperative hypoxia, hypercarbia, ischemia and reintubation. There are 19 cases of patients with OSA in the ASA closed claims database. In 18/19 cases, the patient sustained brain damage or death related to adverse respiratory system events. There is a recent report in the Anesthesia Patient Safety Foundation Newsletter (Lofsky APSF Newsletter 2002; 17:24-5) describing 8 cases of "unexplained" postoperative cardiopulmonary arrests. All patients received parenteral narcotics and were ultimately diagnosed with OSA.

Treatment of OSA with nCPAP may dramatically improve BP control and symptoms of heart failure. None of the case reports of sudden death or cardiorespiratory arrest involved patients wearing nCPAP. One study (Rennotte et al Chest 1995;107:367-74) described 14 consecutive patients effectively treated with nCPAP for 3 weeks preop, nearly continuously postop for 24 hrs and then for all sleep periods. There were no major complications despite the use of opioid analgesics. This highlights the importance of screening patients for symptoms of OSA preoperatively so they can be studied and treated before surgery.

Although there is no data correlating severity of OSA with complications, most authors feel it is reasonable to consider severity of OSA when formulating a management plan. Similarly, the anesthetic technique has not been studied to determine its influence on complications. Regional anesthesia may have advantages by circumventing airway difficulties and limiting the need for sedative and analgesic medications. However, the type of surgery and need for postoperative opioid analgesics is probably more important than the type of anesthetic.

It is not known which OSA patients can safely undergo ambulatory surgery. The recent paper in A&A (Sabers et al Anesth Analg 2003;96:1328-35) found no difference in unexpected admission rates or complications between OSA and weight-matched controls. However, there are several problems with this retrospective study. There was a very high unanticipated admission rate (24%), the controls were obese and not screened for symptoms of OSA, the OSA group was a mixture of treated and untreated and there was no information about complications for patients who were sent home. There are several papers expressing opinions (Tung and Rock Curr Opin Anaesth 2001;14:671-678 and Benumof J Clin Anesth 2001;13:144-156) and one paper that proposes a protocol for management of OSA patients (Deutscher et al APSF Newsletter 2002; 17:58). Ultimately, each institution needs to develop guidelines for management of these patients. I think it is imperative that patients are screened preoperatively for symptoms of OSA and elective surgery postponed until they can be assessed and treated. Adequately treated OSA patients may be considered for ambulatory surgery if they are having minor surgery with minimal need for postoperative analgesics, are alert and are willing and able to use nCPAP themselves at home for all sleep periods.

-- From Janet van Vlymen, MD, FRCPC, Kingston, Ontario, Canada

REPLY:

Any discussion really depends on the type of facility you practice in. I would not allow surgery involving the airway in these patients if I worked in a free standing unit. I feel that these patients should be admitted over-night after general anesthesia and airway surgery. As you know they can be difficult intubations. Most are not. But when these patients are difficult intubations they can be very difficult. Our policy is to approach these patients very cautiously. When in doubt, admit overnight. Their recovery from general anesthesia is often stormy. Sitting them up immediately after extubation helps. Expect lower oxygen saturations early. They usually improve with time. These patients can die in the postoperative period. They are especially sensitive to morphine.

We do surgery on several of these patients every week. Most do well. However, some are challenging postop problems. If you don't want to get hung up in the PACU occasionally, don't do them.

-- From Grover R. Mims, MD, Winston-Salem, NC

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