Volume 4, Issue 8 S A M B A T A L K S - PAGE 1 January, 2005

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Do you have a problem case or situation in ambulatory anesthesia about which you would like some advice? Would you like to reply to questions others have raised about ambulatory anesthesia issues? Do you have any comments or opinions regarding any topic related to ambulatory anesthesia which you would like to share with other professionals? If you answered "yes" to any of the above, then "Join the Discussion" here.

To enter the Discussion with a question, reply, or other comment, please contact us. Your question/reply/comment will be published in this section of the next available issue of SAMBA TALKS. Include your name (or initials), city, and state, if you would like these published. Please note that because of the high volume of questions we receive, there is often a delay of 1 to 2 months before the questions can be published.

Questions and responses from previous months are now available at the eNewsletter Discussion Archive. If you have any comments regarding the previous questions, please submit them to SAMBA Discussion, and they will be published here next month.

?? - LAST MONTH'S QUESTIONS WITH REPLIES - ?? - TOP

QUESTION 1:

Has SAMBA commented on the Canadian survey about BMI?  About 50% of the respondents stated they did ambulatory surgery on patients with a BMI of 45 or less with no other medical problems. Has SAMBA done a similar survey? If OR beds accommodate patients weighing 500 lbs., can we safely anesthetize patients with a BMI of 50 or greater if they are young and have no other medical problems? This issue is more of a problem at our ASC than the morbidly obese patient with concomitant medical problems. It is easier to convince the surgeons that these patients need to be done at the hospital. It is the "healthy" morbidly obese patients that we are constantly questioned about their suitability for ambulatory surgery.
 
-- From Nolana Bell, M.D., Auburn, WA.

REPLY:

Over the past two decades, the US has seen an upward trend in adult obesity, doubling from 15% of the population in 1980 to 31% in 2001 (NHANES: National Health and Nutrition Surveys Data). Body mass index (BMI), describes body weight relative to height and is strongly correlated with total body fat contents in adults. Obesity has been defined as > 30 BMI, and Morbid obesity (MO or Clinically Severe Obesity) as > 35 BMI. The rising prevalence in adults and children has created a national public health problem, and anesthesiologists will be faced with evaluated the eligibility of these patients for anesthesia.

At the last SAMBA Mid-year meeting, I presented information about eligibility of obese patients for ambulatory and office based surgery. No absolute cut-off was provided. In that discussion, the increased morbidity and mortality of obesity patients was linked to the presence of co-morbidities and BMI. Multisystemic effects on cardiovascular (e.g. CAD, HTN, CHF, Pulmonary HTN), respiratory (e.g. sleep apnea, restrictive lung disease, reduced FRC), endocrine (e.g. DM, thyroid disease), musculoskeletal, surgical wound healing and even psychiatric systems need to be considered. There are reported increase risks of premature and sudden death in BMI > 35 (2-13 times); Twice the risk of DVT for BMI > 30; 50-60% of obese patients have mild- moderate HTN; 5-10% have severe HTN, 3-4 times the risk of respiratory depression from sedative/analgesics with a BMI > 35 and a 5% risk of sleep apnea with BMI > 30. Patients having undergone bariatric procedures do not reverse their risks for at least 12 months. As such a proper preoperative evaluation would need to be conducted to identify these risks. Until proven otherwise, patients with BMI > 30 are at increased risk and likely to have any of the associated co-morbidities. In addition to the physiologic stability of the patient, technical considerations, such as appropriately sized equipment, IV access, airway management, and operating room table size influence whether these patients can be done in a non-hospital setting.

With the prevalence of obesity increasing worldwide, it is apparent that clear guidelines are needed. However, to date no evidenced-based guidelines have been formulated. Absent that, a recent publication entitled, Ambulatory Surgery Adult Patient Selection Criteria: A survey of Canadian Anesthesiologists [http://www.cja-jca.org/cgi/content/abstract/51/5/437] tried to address controversial issues in ambulatory surgery patient selection using a short questionnaire. A response rate of 60% from among 1357 anesthesiologists reported that medical conditions with extreme grades of severity (mild or severe) are associated with majority opinion to proceed or not to proceed with surgery. Issues with 75% agreement reflect common practice. The specific conclusions regarding obesity are as follows:

Over 90% of anesthesiologist would include in their patient selection a patient with MO (BMI > 35-44) in the absence of cardiovascular or respiratory co-morbidities. 81.7% of responders would not include these MO patients with BMI > 35-44 in the presence of co-morbidities; and 95.2% of responders would not include severe MO (BMI > 45) with co-morbidities. When asked about severe MO (BMI > 45) without co-morbidities, the responders were split: 49.5% would and 50.1 % would not include them as ambulatory surgery patients. Lack of consensus under these circumstances begs for prospective outcome studies that could serve as a future guide for changing the practice of ambulatory anesthesia.

While the ambulatory surgery environment provides a reasonable alternative for many outpatient procedures, the surgical and anesthesia considerations associated with obesity including anatomic, physiologic, and pharmacologic implications must be seriously considered. The risks and benefits of proceeding in either a hospital, ASC or an office need to be appreciated and discussed with the patient and the surgeon

Selected Reading:

1. Twersky RS. Panel on office-based anesthesia: update on patient eligibility – obese patients ; SAMBA Mid-year meeting, October 22,2004, Las Vegas, NV.

2. U.S. Dept of Health and Human Services. The surgeon general's call to action to prevent and decrease overweight and obesity, 2001. www.cdc.gov/nccdphp/dnpa.obesity/recommendations.htm. accessed Sept 2004

3. Flegal KM, Carroll MD, Ogden CL, Johnson CL. Prevalence and trends in obesity among US adults, 1999-2000. JAMA 2002;288:1723-7.

4. Iverson RE, Lynch D. ASPS Task Force on Patient Safety in Office-Based Surgery Facilities. Patient safety in the office-based surgery facilities: II. Patient selection. Plast Reconstr Surg 2002; 110(7):1785-90; discussion 1791-2

5. DeJong, RH. Body mass index: risk predictor for cosmetic day surgery. Plast Reconstr Surg 2001;108(2):556-61

6. Adams JP, Murphy PG. Obesity in anesthesia and intensive care. Br J Anaesth 2000;85:91-108

7. Davies KE, Houghton K, Montgomery JE. Obesity and day-case surgery. Anaesthesia 2001; 56: 1112-5.

8. Atkins JP, White J, Ahmed K. Day surgery and body mass index: results of a national survey. Anaesthesia 2002; 57: 169-82.

-- From Rebecca Twersky, M.D., Brooklyn, NY

QUESTION 2:

I am the Director of Nursing in a free standing surgery center. We had an increase of post-op nausea and vomiting (PONV). Calculated out there was 10% of the patients having postoperative PONV. It has since decreased to 6.25%. Are these numbers within normal range for PONV? We do general surgery, ENT, podiatry, and plastics.

-- From Cathy Smith, R.N., B.S.N.

REPLY:

The postoperative nausea and vomiting (PONV) rate in a free-standing surgery center will depend not only on the type of surgical procedure but on the anesthetic regimen and on a number of preoperative clinical risk factors. There are literally thousands of clinical studies in this area. From these studies among the most commonly cited factors that predict PONV are female gender, young age, previous history of PONV, and use of narcotics. A rate of 6.25 to 10% on the face of it does not appear excessive. Rates as high as 30% or more are noted in the literature for certain surgical procedure and high risk groups.

Another point worth noting is that PONV is not a binary outcome. Nausea, and vomiting, will vary in severity. Furthermore, antiemetic agents differ in their ability to prevent nausea, compared with prevention of vomiting. To define this more carefully, nausea and vomiting scores, similar to those used for the quantification of pain, are in use in some centers.

Although reduction of PONV is, because of its unpleasantness, a worthy objective for any outpatient surgery center, keep in mind that PONV is only an intermediary outcome. To assess whether your rate is inappropriately high, check whether PONV is itself leading to a
significant number of unexpected admissions, delayed discharge from the facility, or patient dissatisfaction with perioperative care. If that is the case then it is probably worthwhile dissecting out the cause for a higher PONV rate and focusing on preventive and therapeutic measures. By applying multimodal interventions, including multiple antiemetic agents,
adequate hydration, propofol-based anesthesia, avoidance of narcotic analgesics and nitrous oxide, the PONV rate can be reduced to very low levels (Scuderi. Anesthesiology 1999;90:360-371)

-- From Gary Kantor, M.D., Cleveland, OH

?? -- THIS MONTH'S QUESTIONS -- ?? - TOP

QUESTION 1:

We currently have a policy in place and do ambulatory procedures on patients with implanted automatic defibrillators. We turn them off if any form of electrocautery is to be used.  We otherwise leave them on.

Is it appropriate to do such patients in a free standing center and should they always be turned off? We are somewhat concerned in that an AICD may simply be a marker of patients with enough cardiac pathology such that it may be best to simply exclude them.     

-- From B. Evans, M.D.

QUESTION 2:

Is pregnancy testing necessary for EGD/Colonoscopy on female patients?

-- From Mahendra Shah
 

QUESTION 3:

Do any ambulatory surgery sites have criteria-based discharge phone call
processes?  We are currently attempting contact with 100%, reaching only
60% of patients. 

-- From Christine Barrett

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