Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Ambulatory Anesthesia
INTRODUCTION: Propofol is well known to have hypotensive action and the addition of ephedrine 15 or 20mg to 1% propofol 20ml was assessed to be effective to prevent this response . Dopamine (DOA), which acts directly both on alpha and beta adrenoceptors, seems to be another novel method to prevent this problem, especially in case propofol is used both for anesthesia induction and maintenance using infusion pump. We, therefore, studied the effects of continuously administered DOA on prevention of hypotension during the induction with propofol in double blind protocol design in ASA 1 or 2 patients.
METHODS: Thirty-six ASA 1 or 2 patients were divided into three treatment groups. The control group received a normal saline. Group LD received DOA 3 microgram.kg-1.min-1 and the group HD received 5microgram.kg-1.min-1. Following insertion of intravenous cannula, non-invasive blood pressure (BP), ECG and SPO2 were monitored. Then, study drugs were started through a line which is exclusively prepared for DOA infusion. After confirmation that the measured parameters are stable, anesthesia was induced with propofol at the rate of 600ml.h-1 until the patients lost their response to verbal commands and eyelash reflex, hence trachea was intubated following administration of vecuronium. Anesthesia was continued as required for the operation after the study period. BP and HR were monitored continuously and recorded at 1 min intervals for up to 5 min after intubation
RESULTS: The rate of reduction in systolic BP after the induction of anesthesia comparing with which obtained before induction were 20% for control group, 9% for LD group and 5% for HD group. On the contrary, BP increased 17% after intubation in HD group while BP in control and LD groups were mostly unchanged.
DISCUSSION: Continuous infusion of DOA at the rate of both 3 and 5microgram.kg-1.min-1 successfully prevents the reduction in BP during the induction of anesthesia, however, the latter may cause unexpected hypertension after intubation. We, therefore, conclude that the rate of 3microgram.kg-1.min-1 is suitable for reduction in incidence of hypotension during induction of anesthesia with propofol at the rate of 600ml.h-1 without adverse effects in ASA 1-2 patients.
1. Anaesthesia; 1996. 51:488