Over 1,600 abstracts were presented at the 2004 American Society of Anesthesiologist Annual Meeting in Las Vegas, NV. As in previous years, a number of these abstracts examined issues directly related to patient safety. This brief review will highlight some of the important abstracts discussed at the meeting.
Postoperative Neurocognitive Dysfunction
Several investigators examined the incidence and causes of postoperative neurocognitive decline in elderly patients undergoing anesthesia and surgery. In an ongoing prospective study in 130 orthopedic patients older than 65 years of age, Jankowski et al. (A-40) examined the predictors and consequences of postoperative delirium. Neuropsychological and functional testing were performed preoperatively and 3 months postoperatively, and patients were examined daily throughout the hospital stay for the presence of postoperative delirium. Patients who developed postoperative delirium tended to be older and had fewer years of formal education. In addition, an association between postoperative delirium and other major complications (myocardial infarction, dysrhythmias) was observed. An investigation from the University of California (San Francisco) examined the influence of pain medications on postoperative delirium in patients ≥65 years of age scheduled for major noncardiac surgery (A-39). A structured interview was conducted preoperatively and for the first 2 days following surgery to detect the presence of delirium. Multivariate logistic regression analysis revealed age >80 and lower education level were independently associated with increased delirium risk. The use of oral narcotics was associated with a decreased risk of delirium (OR 0.44, CI 0.23-0.85); narcotics administered by other routes did not affect delirium risk. These findings suggest that the method of postoperative pain relief may influence the occurrence of delirium.
Monk and colleagues conducted a prospective, longitudinal study to evaluate the long-term effects of postoperative neurocognitive dysfunction in elderly patients (A-62). Using a battery of tests, the investigators examined 354 patients undergoing major noncardiac surgery preoperatively, at hospital discharge, 3 months, and 2 years after surgery. The cognitive deficit rate was 59% at hospital discharge, 34% at 3 months following surgery, and 42% at the 2-year measurement period. Analysis of the data revealed that cognitive decline at discharge was a significant predictor of long-term cognitive impairment. This well-designed study reveals that many elderly patients are discharged from the hospital with neurocognitive dysfunction, and that this dysfunction may persist for up to 2 years.
Investigators from Parma, Italy, conducted a prospective, randomized trial to evaluate the impact of interventions to improve regional cerebral oxygen saturation (rSO2) on cognitive dysfunction in elderly patients presenting for abdominal surgery (A-61). In the intervention group, rSO2 was maintained above 75% of preinduction values by increasing blood pressure, PaCO2, and FiO2, and by decreasing brain oxygen consumption with a bolus of propofol. In the control group, clinicians were blinded to rSO2 data. In the intervention group, the incidence of postoperative cognitive decline was reduced (35%) and length of stay shortened (9 days), compared to the control group (54% and 13 days, respectively). The authors conclude that techniques to increase rSO2 can potentially improve outcomes in elderly patients.
Use of Perioperative Beta-Blockers
The use of beta-blockers in the perioperative setting has been shown to reduce cardiac morbidity and mortality. Despite clear scientific evidence of the benefit of beta-blockers in appropriate patient populations, few hospitals have protocols for administration of beta-blockers, and many patients at risk for cardiac events do not receive these agents. Two studies from Yale University School of Medicine examined whether the publication of guidelines promoting the use of perioperative beta-blockade increased the use of the drugs at the institution. In the first investigation, data were collected on a cohort of patients (n=230) scheduled for intermediate-to high-risk noncardiac surgery prior to the publication of ACC/AHA guidelines (A-1302). These patients were compared to a similar cohort of subjects operated on following the publication of the guidelines. Nearly half of the patients in each group who were eligible to receive perioperative beta-blockers did not receive them. Approximately three-quarters of each cohort was evaluated by a medical service prior to surgery, yet beta-blocker therapy was recommended by only 51% of consultants. In a similar investigation, the medical records of patients undergoing major vascular surgery were reviewed prior to (n=172) and after (n=197) the publication of the ACC/AHA guidelines (A-204). As demonstrated in the previous investigation, only about one-half of eligible patients received beta-blockers perioperatively in each cohort. In addition, only a small percentage of patients in each group achieved target heart rates ≤60 bpm (22-29%) as recommended by the ACC/AHA. Vigoda et al. examined the resting heart rate of high-risk patients receiving beta-blockers in a preoperative clinic, and compared this to their average heart rate in the operating room (A-1381). Only 27% of patients on chronic beta-blocker therapy had resting heart rates ≤60 bpm in the preoperative clinic, and only 19% had a resting heart rate ≤60 and average intraoperative heart rate <66 bpm. These studies demonstrate that there has been little improvement in the use of beta-blockers in patients at risk for adverse cardiovascular events, and that only a minority of patients receiving this therapy are adequately beta-blocked.
Trace Anesthetic Gases
Current recommendations from OSHA and the ASA state that trace anesthetic gases should be monitored at all anesthetizing locations. Ohmura and colleagues measured trace gases in the patient wards of a cancer institute, a large general hospital, and a small community hospital (A-1329). Measurements were obtained in the morning and afternoon of 3 consecutive days in the operating rooms and in patient wards above and below the ORs. The highest levels of sevoflurane detected in the OR areas were 1.1-1.3 ppm, and in the patient wards, 1.2-1.6 ppm. Trace gases were consistently detected in the wards, even on floors several levels above and below the ORs. The results suggest that other areas of the hospital should be monitored for trace anesthetic gases.
Patients with sleep apnea are at risk for adverse cardiovascular and respiratory events in the perioperative period. Previous studies suggest that a large percentage of patients with sleep apnea remain undiagnosed. In a study from Ontario, Canada, the authors examined the prevalence of sleep apnea in patients presenting for elective surgical procedures (A-13). The Berlin questionnaire was used in patients at a preoperative assessment clinic. This 9-item questionnaire has a high sensitivity and specificity for identifying patients at high-risk for sleep apnea in the primary care setting. The Berlin questionnaire identified 23.9% of all patients at the preoperative clinic as being high-risk for sleep apnea. It also identified all patients in whom a previous diagnosis of sleep apnea had been made. The authors conclude that approximately one-quarter of surgical patients are at high-risk for sleep apnea, and that the Berlin questionnaire can be used to identify those at risk.
Central Line Infection
Berenholtz et al. conducted a prospective cohort study in an intensive care unit setting to determine whether the introduction of a multifaceted systems intervention would reduce the incidence of catheter-related blood stream infections (A-3). All clinicians were educated about evidence-based infection control practices (hand hygiene, chlorhexidine skin prep, maximal barrier precautions, subclavian vein placement). In addition, a checklist to ensure adherence to these practices was used, a central line cart was created, providers were asked daily whether catheters could be removed, and nurses were empowered to stop the procedure if improper techniques were observed. The introduction of these interventions reduced the number of catheter-related blood stream infections from 11.3/1000 catheter days (prior to interventions) to 0/1000 catheter days. The findings from this study demonstrate that strict adherence to an evidence-based infection control policy can markedly reduce the incidence of catheter-related infections. This brief review summarized only a small number of the important abstracts on patient safety presented at the 2004 Annual Meeting. To view other abstracts on patient safety, or to obtain further information on the abstracts discussed in this review, please visit the Anesthesiology website at http://www.anesthesiology.org.
Dr. Murphy is the Director of Cardiac Anesthesia at Evanston Northwestern Healthcare and an Assistant Professor at Northwestern University Medical School in Chicago.
Dr. Vender is Chairman of the Department of Anesthesia at Evanston Northwestern Healthcare and a Professor at Northwestern University Medical School in Chicago.