Jesse J. Muir

Multicenter Study of General Anesthesia. II. Results

A prospective, stratified, randomized clinical trial of the safety and efficacy of four general anesthetic agents (enflurane, fentanyl, halothane, and isoflurane) was conducted in 17,201 patients (study population). Patients were studied before, during, and after anesthesia for up to 7 days. Nineteen patients died (0.11%), and in seven of these (0.04%) the anesthetic may have been a contributing factor. The rates of death, myocardial infarction, and stroke in the study population were so low (less than 0.15%) that no conclusions regarding the relative rates of these outcomes among the four anesthetic agents could be reached. The rates of 16 of 66 types of adverse outcomes in the study population were significantly different among the four study agents. Most of these outcomes were minor. However, severe ventricular arrhythmia (P less than 10(-6)) was more common with halothane, severe hypertension (P less than 10(-6)) and severe bronchospasm (P = 0.028) were more common with fentanyl, and severe tachycardia (P = 0.001) was more common with isoflurane. Recovery from anesthesia during the first 30 min was slowest in those patients who received halothane (P less than or equal to 0.001). In addition, patients who received fentanyl experienced less pain during the first hour in the recovery room (P less than 10(-6)). In conclusion, clinically important differences do exist for some outcomes among the four study agents.

Role of nitrous oxide and other factors in postoperative nausea and vomiting: a randomized and blinded prospective study.

Postoperative nausea and vomiting have been reported to be associated with the use of nitrous oxide. To further investigate this possibility, 780 patients undergoing anesthesia and surgery were randomly divided into four groups: group I: enflurane/nitrous oxide/oxygen; group II: enflurane/air/oxygen; group III: isoflurane/nitrous oxide/oxygen; and group IV: isoflurane/air/oxygen. The frequency of postoperative nausea and vomiting was ascertained in the recovery room and at 24-h follow-up by blinded observers. Other data collected included gender, age, body mass index, previous history of postoperative nausea and vomiting, and postoperative narcotic use. The authors found no association between the use of nitrous oxide and subsequent development of postoperative nausea and vomiting. Use of the 95% confidence interval allowed the authors to project a maximum potential increase in the frequency of postoperative nausea and vomiting associated with nitrous oxide to be 5.4% with enflurane and 9.7% with isoflurane in the immediate postoperative period. Female gender, younger age, and a previous history of postoperative nausea and vomiting, but not body mass index, were found to be associated with postoperative nausea and vomiting (P less than 0.05). It is concluded that there is no association between the use of nitrous oxide and the development of postoperative nausea and vomiting.

Multicenter study of general anesthesia. I. Design and patient demography.

A prospective randomized clinical trial of enflurane, fentanyl, halothane, and isoflurane is described. The 17,201 patients were stratified into two groups (preanesthetic medication and no preanesthetic medication) and were randomized to one of four study agents: enflurane, fentanyl, halothane, and isoflurane. Fifteen university-affiliated hospitals in the United States and Canada participated. All patients were first assessed preoperatively. Data were collected during anesthesia, in the immediate recovery period, and for up to 7 days after anesthesia/surgery. The mean age of the patients was 43 yr, the mean height 167 cm, and the mean weight 68 kg. Sixty-five percent of patients were female. In this study 90.7% of patients were classified as ASA Physical Status 1 or 2, and 34.7% of patients smoked. It is concluded that pooling of data across institutions was valid and does allow determination of the efficacy and relative safety of the four study agents.

Glucose Management in Patients Undergoing Operation for Insulinoma Removal

Medical records of 38 patients undergoing anesthesia and surgery for removal of an insulinoma were reviewed to determine 1) the safety of avoiding intraoperative glucose, 2) the appropriate frequency of plasma glucose analysis, and 3) the accuracy of using rebound hyperglycemia as an indication of tumor removal. Plasma glucose was determined approximately every 15 min during operative and recovery-room periods. The changes in plasma glucose concentrations before tumor removal were compared with those occurring after the resection in each patient by separate linear regressions of glucose concentration versus time. The slopes of the preresection regression lines averaged +0.196 (±SD 0.577) mg-dl-1.min-1. The mean of the postresection slopes was +0.624 (±SD 0.339) ·di-1.min-1. The mean difference in slope (post- minus pre-) was +0.426 (±SD 0.748) ·dl-1.min-1, indicating that a significant (P ≤ 0.02) increase in post-resection slope had occurred. In no case did a preresection plasma glucose concentration decrease to less than 50 mg·dl-1 if the previous value had been 60 mg·dl-1 or greater. Nonetheless, there were nine patients whose plasma glucose did decrease to less than 50 mg·dl-1 at some time during the operative course. Only 39% of patients showed a rebound of 20 mg·dl-1 or more in the first 30 min after resection.The authors conclude that intermittent sampling is safe as long as plasma glucose is kept above 60 mg·dl-1 by infusing glucose. Hyperglycemic rebound is not helpful in determining the adequacy of surgical excision.

Role of Nitrous Oxide and Other Factors in Postoperative Nausea and Vomiting: A Randomized and Blinded Prospective Study

Postoperative nausea and vomiting have been reported to be associated with the use of nitrous oxide. To further investigate this possibility, 780 patients undergoing anesthesia and surgery were randomly divided into four groups: group I: enflurane/nitrous oxide/oxygen; group II: enflurane/air/oxygen; group III: isoflurane/nitrous oxide/oxygen; and group IV: isoflurane/air/oxygen. The frequency of postoperative nausea and vomiting was ascertained in the recovery room and at 24-h follow-up by blinded observers. Other data collected included gender, age, body mass index, previous history of postoperative nausea and vomiting, and postoperative narcotic use. The authors found no association between the use of nitrous oxide and subsequent development of postoperative nausea and vomiting. Use of the 95% confidence interval allowed the authors to project a maximum potential increase in the frequency of postoperative nausea and vomiting associated with nitrous oxide to be 5.4% with enflurane and 9.7% with isoflurane in the immediate postoperative period. Female gender, younger age, and a previous history of postoperative nausea and vomiting, but not body mass index, were found to be associated with postoperative nausea and vomiting (P < 0.05). It is concluded that there is no association between the use of nitrous oxide and the development of postoperative nausea and vomiting.