SummaryA two-stage propofol infusion combined with fentanyl was w e d to maintain anaesthesia during coronary artery surgery in patients with good ventricular function. Whole blood propojol concentrations were measured at frequent intervals; plasma protein binding was measured before, during and after cardiopulmonary bypass. An initial infusion rate of 10 mg/kg/hour provided good protection from the pressor response to sternotomy. A predictable steady state concentration was achieved in the prebypass period with a maintenance infusion rate of 3 mglkglhour. The onset of bypass resulted in a small decrease in propofol concentration as a result of haemodilution. Induced hypothermia resulted in an increase in propofol concentration which returned rapidly to the prebypass steady state value during rewarming. The free propofol fraction increased during cardiopulmonary bypass. No patient had any recall of operative events or required inotropic support during weaning from bypass. Key wordsAnaesthesia; cardiovascular. Anaesthetics, intravenous; propofol.Propofol, a new intravenous anaesthetic agent, is suitable for maintenance of anaesthesia by infusion. It has been used recently for coronary artery surgery performed during cardiopulmonary bypass (CPB).1*2 Hypothermic CPB causes many physiological changes which have clinically significant effects on the disposition and elimination of drugs.3 This study was designed to assess the suitability of a two-stage propofol infusion for cardiac surgery and in particular to study the effect of hypothermic CPB on the kinetics of the drug. MethodsThe study received institutional ethics approval and each patient gave written informed consent. Ten male patients were studied; all were scheduled for coronary artery surgery with internal mammary artery anastomosis to the left anterior descending coronary artery. All had good or only moderately impaired ventricular function as defined by an ejection fraction of approximately 50%. All were receiving maintenance doses of a beta-adrenoceptor antagonist (metoprolol or atenolol), a calcium antagonist (nifedipine) and a nitrate (isosorbide dinitrate or glyceryl trinitrate). These drugs were continued up to and including the morning of operation.Premedication consisted of sodium amylobarbitone 300 mg on the evening before operation and diazepam 1 6 1 5 mg one hour before operation. Radial artery pressure monitoring was established under local anaesthesia. Electrocardiographic (ECG) monitoring was applied and lead 11 displayed continuously. Anaesthesia was induced with fentanyl 25 pg/kg, diazepam 0.1 mg/kg -and pancuronium 0.15 mg/kg, and the lungs were ventilated with oxygen-enriched air to normocapnia. An infusion of propofol at the rate of 10 mg/kg/hour was established through a dedicated peripheral arm vein 10 minutes before skin incision and continued for 15-20 minutes during which time sternotomy and sternal spread were performed. The infusion was then reduced to a maintenance rate of 3 mg/kg/hour until the final skin suture had been inserte...

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BACKGROUND: Cocaine has a short biological half-life, but inactive urine metabolites may be detectable for a week following use. It is unclear if patients who test positive for cocaine but have a normal electrocardiogram and vital signs have a greater percentage of hemodynamic events intraoperatively. METHODS: A total of 328 patients with a history of cocaine use who were scheduled for elective noncardiac surgery under general anesthesia were enrolled. Patients were categorized into cocaine-positive versus cocaine-negative groups based on the results of their urine cocaine toxicology test. The primary aim of this study was to evaluate whether asymptomatic cocaine-positive patients had similar percentages of intraoperative hemodynamic events, defined as (1) a mean arterial blood pressure (MAP) of <65 or >105 mm Hg and (2) a heart rate (HR) of <50 or >100 beats per minute (bpm) compared to cocaine-negative patients. The study was powered to assess if the 2 groups had an equivalent mean percent of intraoperative hemodynamic events within specific limits using an equivalence test of means consisting of 2 one-sided tests. RESULTS: The cocaine-positive group had a blood pressure (BP) that was outside the set limits 19.4% (standard deviation [SD] 17.7%) of the time versus 23.1% (SD 17.7%) in the cocaine-negative group (95% confidence interval [CI], 0.5–7.0). The cocaine-positive group had a HR outside the set limits 9.6% (SD 16.2%) of the time versus 8.2% (SD 14.9%) in the cocaine-negative group (95% CI, 4.3–1.5). Adjusted for age, sex, body mass index (BMI), smoking status, and the presence of comorbid hypertension, renal disease, and psychiatric illness, the cocaine-positive and cocaine-negative patients were similar within a 7.5% margin of equivalence for MAP data (β coefficient = 2%, P = .003, CI, 2–6) and within a 5% margin of equivalence for HR data (β coefficient = 0.2%, P < .001, CI, 4–3). CONCLUSIONS: Asymptomatic cocaine-positive patients undergoing elective noncardiac surgery under general anesthesia have similar percentages of intraoperative hemodynamic events compared to cocaine-negative patients.