A COMPARISON OF NEUROLEPT, BALANCED, AND INTRAVENOUS PROPOFOL ANESTHESIA .1. DESIGN AND PATIENT DEMOGRAPHICS

The choice of appropriate anaesthesia in a more or less seriously ill patient requires detailed information on the risk and tolerance of eac h specific anaesthetic regimen. The objective of this prospective, ran domised clinical trial was to test the hypothesis that three regimens of general anaesthesia - neurolept - (NLA), balanced (BAL), and intrav enous propofol anaesthesis (IVA) - differ with regard to safety and co mfort. The criteria for the intraoperative safety and postoperative co mfort of the patients were the incidents, events and complications (IE C) that required medical treatment as well as the evaluation of postop erative complaints by the patients according to the IEC list and patie nt questionnaires of the German Society of Anaesthesia and Critical Ca re Medicine (DGAI). Methods. The study duration was about 4 months, fr om January to April 1992. During this period the patients of all nine operative departments of the hospital received strictly randomised NLA , BAL, or IVA. Patients who had regional anaesthesia or were not capab le of understanding the German language, were nonco-operative, or were seriously ill (ASA class IV to V) as well as children under 18 years of age did not participate in the study. All eligible patients provide d their informed consent. Anaesthesia. For premedication 10 mg chloraz epate was administered the night before and on the day of surgery. Ana esthesia was conducted under normoventilation using a mixture of 70% n itrous oxide and 30% oxygen. NLA patients were induced intravenously w ith 0.2 mg/kg body weight etomidate and received 0.005 mg/kg fentanyl and 0.07 mg/kg droperidol before the start of surgery. The repetition dose was 0.2 mg fentanyl and 2.5 mg droperidol. In the BAL patients th e dose of fentanyl and droperidol was reduced to 50% due to the additi on of isoflurane up to 1 vol. %. IVA patients received 2 mg/kg propofo l over 3 min followed by an infusion of 3-5 mg/kg per hour together wi th 0.2 mg fentanyl/h. Neuromuscular blockade was accomplished with vec uronium 0.1 mg/kg. If the blood pressure and heart rate increased by m ore than 20% of preoperative values, analgesia was reinforced by an ad ditional fentanyl dose. Anaesthesia was subsequently enhanced by incre asing the neurolept/propofol/isoflurane dose by up to 50%. Data collec tion. The following parameters were registered: patients' personal dat a and physical condition according to ASA classification; the grade of risk according to the Munich risk checklist; the frequency of IEC dur ing surgery; the patient' permanent medications; postanaesthetic vigil ance and recovery; the acceptance of the assigned anaesthetic by the p hysician: the cost of the anaesthetic used; and pre- and post-operativ e complaints as well as the assessment of anaesthesia by the patient. The statistical evaluation was performed using the chi-square test. Re sults. A total of 1,346 patients were enrolled in the study; 28 (2%) w ere excluded because the treatment protocol was changed by the anaesth esiologist. Seventy per cent were recruited from general, gynaecologic , or otorhinolaryngologic surgery. The three anaesthetic regimens (NLA , BAL, and IVA) were used in other departments with the same fre-quenc y with the exception of ophthalmology and urology (P > 0.1) (Fig. 1). Of the 1,318 eligible patients, 443 received NLA, 443 BAL, and 432 IVA (P = 0.8). The distribution of the various parameters was surprisingl y similar among the three groups: the average age was 50 years (P = 0. 91), body weight 71 kg (P = 0.33), reference or initial blood pressure 130/80 mm Hg (P = 0.36), average time of anaesthesia 103 min (P = 0.4 2), and all had the same risk score (P = 0.42). Sixty per cent were fe male. An average of 85% of the 18- to 89-year-old patients were consid ered to be healthy according to the ASA risk classification (P = 0.42) . However, on applying the Munich risk checklist the average number of healthy individuals was 5% to 10% lower than that of the ASA risk cla ssification. The average quantity of anaesthetics per patient in the N LA group was 7.1 mg droperidol and 0.54 mg fentanyl; in the BAL group the amount could be reduced to 50% by adding isoflurane, and in the IV A group propofol 493 mg/100 min was given with 0.3 mg fentanyl (Fig. 2 ). The costs of the three regimens were 27.43 DM for NLA, 31.68 DM for BAL, and 43.75 DM for TVA. Conclusion. The remarkably high degree of consistency of the patients' baseline characteristics as well as the e qual distribution among the patient groups can be considered optimal r andomisation. The present clinical trial compared the safety and toler ance of the three anaesthetic regimens under routine daily conditions. The results of the study should have great clinical significance for the choice of the appropriate anaesthetic regimen while considering sa fety, tolerance, and cost-benefit aspects.