ASA April 2003 Newsletter

SAMBA and Evidence-Based Medicine: Turning Anecdotes Into Facts

Lydia A. Conlay, M.D., Ph.D., President
Society for Ambulatory Anesthesia

Many of the changes that have taken place in ambulatory practice over the past decade have happened far in advance of any evidence demonstrating safety, and in some cases, even efficacy. The acuity of patients in hospitals increased over a decade ago at the same time that ambulatory cases were moving to the more efficient and patient-friendly outpatient surgical centers. Now the acuity of patients in these centers also has increased because simpler cases (at least they are usually simpler cases) are moving into the office setting. Of course, we are frequently called upon to provide care in such situations before there is any evidence that they are actually safe.

As president of the Society for Ambulatory Surgery (SAMBA), I have been invited to report on topics of interest to our membership and to ASA’s membership as well. Few items have excited as much interest within SAMBA as those studies that fall into the categories of evidence-based medicine or “outcomes studies.” Whether traveling to a physician’s office in tandem with a postanesthesia care unit nurse, evaluating patients in the anesthesiologist’s office prior to an office procedure or testing the limits of a 23-hour stay, outcomes studies have become increasingly important to aid practitioners’ attempts to understand the limits within which we can safely practice — or to put it another way, to define the margins of the envelope itself. Evidence-based decision making accounts for the inherent flaws in human wiring, which makes us particularly prone to errors in judgment when evaluating issues that involve probability. How many of us have heard, “I have done over 20 of these now and haven’t noticed any problems”? Nor, by the way, was the potential for any problems necessarily monitored. Should an average of one in 21 patients suffer a fatal complication, few would consider the resulting 5 percent mortality rate to be acceptable. As humans, we innately tend to value the new, the unusual or, all too often, the anecdotal at the expense of the familiar, the proven or the “tried and true.”

SAMBA is addressing these issues by supporting clinically based research by top-flight investigators that can be translated easily and directly into useful information for the typical practitioner who cares for ambulatory patients today. We do so in part because our practices continue to move forward at an extraordinary pace and because of public pressure to improve outcomes and to reduce errors following medical procedures. During the past year, several “outcomes-based” themes have garnered much interest.

How old is too old, and how sick is too sick? Fleisher et al. attempted to answer these two questions in a study funded by SAMBA.¹ In a cohort of more than 1.2 million patients, age in excess of 85 years was found to be one of the strongest predictors of hospital admission and death within seven days of a surgical procedure, thus suggesting that even young-appearing patients over 85 suffer an increased operative risk from surgery. Similarly, older patients with more complicated comorbidities were more likely to require admission even following a minor “outpatient” surgical procedure, suggesting that they may be less suitable for surgery in a freestanding facility. With respect to the presence of comorbidities, the good news was that outpatient anesthesia was proven to be very safe. The risks of hospital admission or death following an ambulatory procedure were influenced by the duration of the operative time or the presence of cardiovascular disease, malignancy or an HIV-positive status. The exception to this rule remains, of course, cataract surgery, which has a very low morbidity and mortality rate even in patients with significant disease.²

Pain is a major issue influencing the outcome of ambulatory patients. If this seems like a familiar refrain, it may be worth noting that, in 1989, Gold and colleagues reported in the Journal of the American Medical Association that almost 20 percent of patients undergoing ambulatory procedures were admitted to the hospital unexpectedly from pain.³ This is not meant to imply that there have not been significant advances in analgesic therapies in the ensuing years. However, it is possible, if not probable, that the improvements in analgesia simply have not kept up with expansions in surgical procedures considered appropriate for ambulatory care. In a recent article by Pavlin et al., the surgical procedure was indeed the major predictor of postoperative pain. Pain was, in turn, the major predictor of recovery time.⁴ Gebhard and colleagues demonstrated that almost 40 percent of ambulatory patients had significant pain during the first 24 hours postoperatively, but the pain was attenuated in some orthopedic patients receiving peripheral nerve blocks.⁵ Atiyeh and Philip reported a high percentage of both pain and postoperative nausea and vomiting (PONV) postoperatively following central neuraxial blockade.⁶ It is thus important to remember to provide pain management following a central neuraxial block at home.

The COX-2 inhibitors are undoubtedly one of the most exciting entries into the anesthesiologist’s armamentarium. Clearly superior to acetaminophen or placebo, their administration is associated with reductions in pain, PONV, improved oral intake and return to normal activity. These compounds also may reduce the resources necessary to manage postoperative pain as well as other indices of outcomes such as length of stay and patient satisfaction.^7,8 We hope to see a parenteral version out later this year.

Obstructive sleep apnea. This condition continues to be a serious concern since tools cannot reliably indicate which patients with obstructive sleep apnea are appropriate for ambulatory surgery. Warner and colleagues reported that neither disturbed breathing patterns nor obstructive sleep apnea increased the likelihood of a difficult intubation or an unplanned hospital admission.⁹ Consensus suggests the avoidance of midazolam and miserly use of muscle relaxants in patients with obstructive sleep apnea, but actual evidence of precipitating factors for postoperative complications has not been forthcoming.

The culture of evidence-based medicine. A stellar example of a decisive action not related to outcome was the Food and Drug Administration’s recent “black box” warning for droperidol. Despite several large, randomized, controlled studies showing that droperidol (in low doses) was as safe as ondansetron and/or placebo, the warning was placed on the basis of 10 anecdotal reports from patients receiving a myriad of other drugs that also could have precipitated the catastrophic event. We can only hope that as the evidence-based culture expands, such decisions will be based on scientific evidence and clinical outcomes. SAMBA continues to support such efforts to scientifically direct practice in our rapidly expanding field. Due to the fact that ambulatory practices administer more than 70 percent of all anesthetics today, we welcome your support in these endeavors.

References:

1. Fleisher LA. Outcomes in ambulatory anesthesia related to location of care. Session 3. Presentation at Society for Ambulatory Anesthesia Mid Year Meeting 2002. [unpublished].

2. Schein OD, Katz J, Bass EB, et al. The value of routine preoperative medical testing before cataract surgery. N Engl J Med. 2000; 342:168-175.

3. Gold BS, Kitz DS, Lecky JH, Neuhuas JM. Unanticipated admission to the hospital following ambulatory surgery. JAMA. 1989; 262(21):3008-3010.

4. Pavlin DJ, Chen C, Penaloza DA, et al. Pain as a factor complicating recovery and discharge after ambulatory surgery. Anesth Analg. 2002; 95(3):627-634.

5. Gebhard RE, Pivalizza EG, Warters RD, et al. Pain after discharge from ambulatory surgery — Orthopedic patients benefit from peripheral nerve blocks. Anesthesiology. 2002; A-25. (American Society of Anesthesiologists Annual Meeting abstracts are available online at: <www.asa-abstracts.com>.)

6. Atiyeh L, Philip BK. Adverse outcomes after ambulatory anesthesia: Surprising results. Anesthesiology. 2002; A-30. (American Society of Anesthesiologists Annual Meeting abstracts are available online at: <www.asa-abstracts.com>.)

7. Joshi GP. Patient postdischarge symptom experience after single presurgery dose of IV parecoxib sodium, a novel COX-2 inhibitor, followed by oral valdecoxib for pain associated with laparoscopic cholecystectomy. Anesthesiology. 2002; A-29. (American Society of Anesthesiologists Annual Meeting abstracts are available online at: <www.asa-abstracts.com>.)

8. Klein KW, Issioui T, White PF, et al. Role of COX-2 inhibitors in preventing pain after outpatient ENT surgery. Anesthesiology. 2002; A-36. (American Society of Anesthesiologists Annual Meeting abstracts are available online at: <www.asa-abstracts.com>.)

9. Warner DO, Sabers C, Schroeder DR, et al. Obstructive sleep apnea as a risk factor for unanticipated admissions after outpatient surgery. Anesthesiology. 2002; A-31.(American Society of Anesthesiologists Annual Meeting abstracts are available online at: <www.asa-abstracts.com>.).

Lydia A. Conlay, M.D., Ph.D., is Professor and Chair, Baylor College of Medicine, The Methodist Hospital, Houston, Texas.

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