Etomidate-analgesic combinations for the induction of anaesthesia in cardiac patients. Part I: Studies in patients with coronary artery disease.
In a total of 150 patients undergoing coronary revascularization procedures etomidate was given for the induction of anaesthesia using 12 different dosages and combinations with piritramide, morphine, fentanyl and nitrous oxide. The aim of this study was to establish a method which would result in the smallest possible changes in arterial blood pressure and heart rate during the whole of the induction period, including the stressful phase of endotracheal intubation. In 68 patients cardiac output and pulmonary artery pressure were also measured.


RESULTS
1. In general, more favourable results were obtained when anaesthetic drugs were administered extremely slowly (e.g. by infusion) and according to a standardized dosetime regime. Conversely, the commonly used method - slow incremental injections according to the estimated requirements of the individual patient - led to much greater variations of arterial pressure, especially when fentanyl was combined with etomidate. 2. Combinations of etomidate and morphine led to unsatisfactory results. Dependent on the dose given, hypertension or hypotension were commonly seen. When piritramide was substituted for morphine much more stable haemodynamic conditions were obtained. 3. Surveying our investigations to find the most suitable dose relationship between the hypnotic, etomidate, and the opioid analgesic, piritramide, only small and negligible differences were found: comparing two procedures for the induction of anaesthesia using either high dose piritramide (3 mg . kg-1 given over 10 min), supplemented by low dose etomidate (0.1 mg . kg-1 given over the first 2 min) or an etomidate infusion (50 gamma . kg-1 . min-1) supplemented by a low dose piritramide (0.3 mg . kg-1 given over 1 min) excellent results were found in both groups. 4. In contrast, studies aimed at achieving equally favourable results using the combination of etomidate-fentanyl suggested that the safe dose-range of fentanyl is very narrow: etomidate-infusion (50 gamma . kg-1 . min-1) together with fentanyl 3 gamma . kg-1 led to unacceptable rises in blood pressure and heart rate after intubation, and the larger dose of 6 gamma . kg-1 fentanyl frequently led to hypotension.
D000700:Analgesics; D000758:Anesthesia; D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology; D003327:Coronary Disease / Q000503:physiopathology; D005045:Etomidate; D005283:Fentanyl; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007093:Imidazoles; D008875:Middle Aged; D009609:Nitrous Oxide; D010892:Pirinitramide
D000700:Analgesics; D002121:Calcium Channel Blockers; D007093:Imidazoles; D010892:Pirinitramide; D009609:Nitrous Oxide; D005283:Fentanyl; D005045:Etomidate