There's no denying that the patients presenting for outpatient surgery are increasing in size and in the number of co-morbidities - specifically obstructive sleep apnea. In this condition, the neck and jaw muscles relax during sleep, resulting in the potential for tissue in the airway to obstruct air flow. Patients who have OSA are at a greater risk both intra- and post-operatively for such negative outcomes as increased respiratory complications, hospital transfers, post-discharge breathing difficulties due to anesthesia and opiates, and possibly death. And you wouldn't believe how many overweight and obese patients don't know they suffer from or have symptoms of OSA. According to the literature, 80 percent to 90 percent are undiagnosed.

While we weren't experiencing significant problems with morbidly obese patients, we knew there was greater potential for negative outcomes with this group, and we wanted to be at the fore of safety. However, there are no clear evidence-based guidelines for outpatient surgical facilities to follow or from which to develop policies. So we took matters into our own hands, undertaking our own study and literature review (see "Inside Our OSA Survey" on page 48).

The result is a body mass index/constant positive airway pressure protocol that has ensured enhanced safety for our overweight and obese patients - we've not had a single complication attributable to OSA in the past five-plus years. Here's how we at the Frederick Surgical Center in Maryland devised our BMI/CPAP protocol and how you can apply it to your facility.

Baseline standards
We began our sleep apnea efforts in August 2000. If a patient had been diagnosed with OSA and had a CPAP machine at home, the medical director automatically reviewed the patient to ensure he was a safe, appropriate candidate for surgery in the ASC. As we began seeing this type of patient more frequently, we instructed patients to bring their CPAP machines with them the day of surgery. But all too often, the patient didn't know how to use it, it was dirty or we found it wasn't working properly. In other words, CPAP machines for at-home use were useless the vast majority of the time. We realized we needed to develop operative and discharge protocols that would assume none of our patients had CPAP machines and we bought one of our own as a precaution.

However, that only took care of our patients with known OSA - we also needed a way to screen for patients with undiagnosed OSA and reduce the risk of unforeseen complications in a larger number of patients. Therefore, all patients having a BMI greater than or equal to 45 were screened and continually evaluated. We noted that patients with BMIs even below 40 increasingly had histories of sleep apnea or other co-morbidities. This clinical evidence and a literature search indicated that morbid obesity was defined as BMI of 35 of greater, so we adjusted the parameters for screening accordingly.

Preemptive strike
The BMI/CPAP protocol consists of eight questions that we ask patients by phone to further evaluate their risk factors.

• Does the patient have a history of sleep apnea?
• Does the patient have a history of snoring? (It's often a good idea to get the spouse or partner to answer this one.)
• Does the patient have a history of chronic fatigue?
• Does the patient wake frequently at night?
• Does the patient experience episodes of apnea during sleep?
• Does the patient use or have a history of using CPAP or apnea monitoring?
• If using CPAP, do you use it on a regular basis?
• Does the patient have a history of congestive heart failure?

Based on this information, we'd perform further work-up, such as an EKG, regardless of the patient's age. (Previously, advanced patient age or known cardiac disease were the only indicators for EKG.) Anesthesia would then evaluate these patients for appropriateness in the outpatient setting. If further work-up or sleep studies are indicated, we'd complete those before we determined anesthesia care. This lets us reschedule the patient elsewhere if necessary and prevents inconvenient day-of cancellations. And if the patient can be operated on in our center, we can assure him of a top level of safety.

Anesthesia's expertise
Thanks to our aggressive screening, anesthesia is well-prepared to review patients pre-operatively to determine the setting, appropriate anesthetic technique and post-op pain relief, and supplemental OSA treatment. Here's how.

• Hospital or ASC? Anyone with a BMI over 50 or a weight over 400 pounds is automatically deemed not a candidate for general or regional anesthesia. If this was the original plan, the medical director considers alternatives. And if we can't safely implement those, the protocol refers the individual for inpatient care to ensure safety. Other times, it's a judgment call. If the procedure requires several hours under general anesthesia or a lot of narcotics post-op, the hospital may be more appropriate. Patients with severe, previously undetected OSA also aren't good candidates; post-surgery recovery isn't the time for patients to learn to use CPAP. If the patient is high-risk, and the surgeon insists on general, the procedure should be done in the hospital.
• General, regional or MAC? There is no easy answer to this question, but there are guidelines to follow. We recommend regional on OSA patients whenever possible. For example, having orthopedic surgeries on the shoulder, elbow, wrist and knee can be done using this technique. Patients have to agree to the use of the technique, but that's not usually a problem once they've been educated on it. We can use monitored anesthesia care for minor cases like carpal tunnel or small lesion excision, where there isn't much pain involved. But even when doing MAC, you have to be prepared to administer general anesthetic, because the plan may change at a moment's notice, depending on the patient's status during surgery. We have the difficult airway cart immediately available for OSA patients - up to about 5 percent of whom have what's classified as a difficult airway. Our difficult airway cart includes laryngeal mask airways, a Fastrack LMA, various laryngoscope blades and endotracheal tubes, a fiberoptic bronchoscope and a Bullard scope.
• Is CPAP needed? Anybody already on CPAP pre-op would be a candidate for its use post-op. If a patient appears to have OSA based on our screening, and shows signs of airway obstruction, leading to hypoventilatory hypoxia, we would require CPAP in the post-op period.
• How to avoid opiates? Obviously, we want to provide all patients with adequate pain control, but opiates depress respiratory function. So whenever we can, we try to use local anesthetic at the incision site or use regional anesthesia for post-op pain control. For example, an interscalene nerve block before shoulder surgery will usually leave patients comfortable when they wake up and not requiring narcotics. We also administer toradol for supplemental pain relief.

Confident discharge
After our study, we felt that we should have a CPAP machine available for post-op care - if, despite pre-op screening and anesthetic precautions, patients were having trouble waking up and breathing on their own in recovery. We worked with the respiratory department at the local hospital because it had recently evaluated several types of CPAP. We trialed their recommendation and were satisfied with its simplicity of use and the $850 price tag. We've only had to use it once in two years, but knowing it's there if we need it is reassuring.

As long as there are no complications or problems post-op (none so far), patients are discharged according to normal protocols. If the plan is for patients to use CPAP at home, we instruct them to follow these guidelines to prevent apnea during their home recoveries:

• Use the CPAP machine while resting for the first 24 hours post-op, and every normal sleep cycle thereafter using physician-prescribed settings. The machine is not necessary when moving about.
• Be in the company of a responsible adult companion for 24 hours to ensure use of the CPAP and to monitor pressure requirements during sleep.
• If you have one, use a dental device to assist with your OSA while at rest for the first 24 hours.
• When using pain medications, narcotics or sedatives of any kind, use the CPAP machine while at rest. If the surgeon orders these medications, inform him or her of your history of OSA before taking them.
• Maintain CPAP equipment according to manufacturer's guidelines, and ensure that pressure and alarm settings are as prescribed by the ordering physician.
• Sleep on your side or sitting up in a chair whenever possible.
• If PONV impedes use of the CPAP, notify your surgeon.
• Avoid the use of alcohol.
• Report any problems to your physician immediately or seek assistance at the nearest emergency room.

Easy implementation
A lot of surgical facilities might say we're overly aggressive, but we feel safety is of the utmost priority. We would rather postpone a surgery or have it moved to the hospital setting than take the risk at our ASC. After all, if there's a good chance a patient will end up in the hospital, he may as well start there.

Our anesthesiologists are also our medical directors, so they're very involved in the decision-making. Their leadership means all the anesthesia providers are on board, and the physicians have quickly come around.

With our policies firmly in place, we need only stay current on the literature to ensure we maintain best practices in screening, follow-up referral and patient education.