Safety-Related Abstracts Prominent at Orlando ASA

Glenn S. Murphy, MD; Jeffery S. Vender, MD

Nearly 1400 abstracts were presented at the 2002 American Society of Anesthesiologists Annual Meeting in Orlando. During 6 poster sessions, more than 100 scientific papers were exhibited that related directly to patient safety. The following review will highlight a few of the many interesting abstracts directly related to patient safety.

Preoperative Evaluation

The administration of beta-blocking drugs to high-risk surgical patients may reduce the risk of adverse cardiac events. Rapchuk et al. (A-1077) determined the frequency of use of beta-blockers in patients presenting for major non-cardiac surgery. They examined 222 patients who were scheduled to undergo major non-cardiac surgery. Ninety-six of these subjects met previously established criteria for beta-blocker use. Only 40% of these candidates for beta-blocker use were receiving these drugs preoperatively. The authors estimate that 40-80 deaths could be prevented each year at their institution if appropriate use of beta-blocking drugs was instituted.

The North American Society of Pacing and Electrophysiology recommends that pacemaker patients receive a telephone check every 3 months and an in-office evaluation every year. Rozner et al. (A-1071) examined compliance with these guidelines in a group of 161 preanesthetic pacemaker patients. Overall, 42% of patients were not compliant with the telephone check, and 32% had no in-office evaluation within a year. Pacemaker malfunction (battery depletion or inadequate or potentially injurious settings) that required an intervention was noted in 15% of patients. These findings support the American College of Cardiology recommendation that patients with pacemakers receive a preoperative interrogation.

Kozack et al. (A-1204) mailed a questionnaire to 168 individuals to determine if the incidence of chronic muscle pain is higher in patients susceptible to malignant hyperthermia (MH). One hundred and six subjects who tested positive to the Caffeine Halothane Contracture Test (CHCT) were compared to 62 subjects who tested negative. Thirty-eight percent of MH susceptible individuals reported chronic muscle pain, compared to only 14% of those who tested negative. The authors observed that MH susceptible patients may not be asymptomatic, as previously reported, and that symptoms of chronic muscle pain are common in those who test positive on the CHCT.

Several papers examined the use of herbal medications in surgical patients. Herbal medications have the potential to induce cardiovascular changes, alter drug metabolism, and increase the risk of bleeding in the perioperative period. Nearly 30% of high-risk surgical patients (A-1184), 18% of preoperative cancer patients (A-1129), and 5% of pediatric surgical patients (A-1236) were found to be using herbal medications immediately prior to their surgical procedures. These surveys demonstrate that a high percentage of surgical patients are regularly using herbal supplements; clinicians should routinely ask their patients about use of these drugs.

Postoperative Complications

Weldon et al. (A-1097) evaluated the relationship between anesthetic depth during elective major surgery and mortality during the first postoperative year. BIS data were recorded in 907 adult patients undergoing major surgery of at least 2 hours duration. The percentage of time the BIS values were <40, 40-60, and >60 were recorded. Logistic regression modeling revealed that increasing age (P=0.001) and lower BIS values (P=0.001) were independently associated with higher mortality rates. These findings suggest that maintaining deeper level of anesthesia in patients older than 40 years of age may be associated with higher 1-year mortality rates (see Advancing Age/Deeper Anesthesia, page 61).

Two abstracts presented data from the ASA Closed Claims Project. Spitellie et al. (A-1124) analyzed claims for central line injuries. Compared to other claims in the database, central line cases had a greater severity of injury (46% resulted in death). Pericardial tamponade and pulmonary artery rupture had a higher proportion of death (83% and 100%, respectively). Lee et al. (A-1126) assessed liability associated with regional anesthesia in the operating room. A higher percentage of temporary or non-disabling injuries occurred in regional anesthesia claims compared to other surgical anesthesia claims (64% vs. 46%), with obstetrics accounting for nearly half of these minor cases. Median payments for regional claims ($85,750) were significantly lower than claims for other surgical anesthesia cases ($117,000).

Fleisher et al. (A-1127) examined the safety of conducting surgical procedures on an elderly patient population in the outpatient setting. The rates of death and admission to an inpatient hospital were determined in a 5% sample of Medicare beneficiaries between the years 1994-1999. A total of 564,267 procedures were studied in the settings of outpatient hospitals, ambulatory surgical centers, and offices. A low mortality rate on the day of surgery (2.4 per 100,000 cases) and a small number of admissions to an inpatient hospital (8.41-21 per 1000 cases) were noted. Variables associated with adverse outcomes included increasing age, prior admission within 6 months, and invasiveness of the surgery.

Surgical patients are at risk for developing hypoxemia in the postoperative period, which may contribute to adverse outcomes. Curry et al. (A-1173) compared the number of hypoxemic events recorded with continuous central pulse oximetry to that recorded on the patients’ charts during the first 48 hours following abdominal surgery. Using central pulse oximetry, more than 1,200 episodes of oxygen saturation <90% were recorded in the 69 study patients. However, only 9 episodes of hypoxemia were recorded in the patients’ charts. These findings suggest that the majority of hypoxemic events that occur in the postoperative period may be missed by clinicians caring for the patient.

Miscellaneous

Mertes et al. (A-1083) examine the causes of anaphylactic reactions during anesthesia at 40 allergo-anesthesia centers in France over a 2-year period. Over 500 patients were diagnosed with an anaphylactic reaction during anesthesia by clinical history, skin tests, and IgE assays. Seventy percent of the reactions occurred in females. Fifty-nine percent of anaphylactic reactions were attributed to neuromuscular blocking agents; succinylcholine and rocuronium were the most frequently incriminated agents. More than two-thirds of the episodes resulted in life-threatening reactions or cardiac/respiratory arrests.

In the past, a subset of patients admitted for epiglottitis required general anesthesia and endotracheal intubation. Swamidoss et al. (A-1182) examined a New York State database during the year 2000 to determine the demographics and management of epiglottitis. Thirty patients were admitted in the year 2000 with a diagnosis of epiglottitis. Males comprised 60% of the sample, and only 1 patient was less than 4 years of age. No patients required general anesthesia or tracheostomies. The incidence of epiglottitis in pediatric patients appears to be decreasing, and the need for general anesthesia with tracheal intubation is also declining.

In December 2001, the FDA issued a “black box” warning about the potential of droperidol to induce cardiac arrhythmias. Norton et al. (A-1196) analyzed the 273 case reports upon which the warning is based. Adverse cardiac outcomes occurred in 74 of these cases. Most of these (57/74) involved excessive doses of droperidol (50-600 mg). In only 17 of the 74 reports was droperidol the sole drug administered, and the dose administered was 2.5 mg or less in only 5 of these cases. On the basis of this data, the authors concluded that the FDA warnings about droperidol do not appear to be justified.

This review summarizes only a portion of the abstracts related to patient safety that were presented at the ASA Annual meeting. All of the abstracts from the 2002 meeting may be viewed at the Anesthesiology web site at www.anesthesiology.org.

Dr. Murphy is the Director of Cardiac Anesthesia at Evanston Northwestern Healthcare and is an Assistant Professor at the Northwestern University Medical School in Chicago, IL.

Dr. Vender is Chair of the Department of Anesthesia at Evanston Northwestern Healthcare and is a Professor at Northwestern University Medical School in Chicago, IL.