Effects of the bolus injection rate on anesthesia induction with propofol]

We examined the influence of the bolus injection rate of propofol on the cardiovascular depression and injection pain. Fifty-one patients of ASA grade 1 or 2 were randomly allocated to two groups. After premedication with midazolam 0.06 mg.kg-1 and atropine 0.006 mg.kg-1 i.m., propofol 2 mg.kg-1 was injected to a forearm vein at a rate of 800 ml.hr-1 in Group A or 1 ml.s-1 in Group B. Anesthesia was maintained thereafter with 67% nitrous oxide in oxygen and propofol infused at 6 mg.kg-1.hr-1. The incidence and severity of pain on injection were lower in Group B compared with Group A, but the difference was not statistically significant. The induction time was significantly shorter in Group B than in Group A (40 vs. 73 sec: P < 0.01). There were no significant differences between the two injection rates in peak reductions in systolic and diastolic blood pressure and heart rate. In conclusion, rapid injection of propofol was effective to shorten the induction time without any adverse effects.