Effects of different propofol injection speeds on blood pressure, dose, and time of induction

Aim: Blood concentration of propofol depends on many factors, such as age, gender, body weight, dose, infusion rate, and cardiac output. This study primarily investigated the effect of infusion rate on blood pressure changes. Secondarily induction time and induction dose were studied.Materials and methods: Propofol was administered at 200 (P200), 300 (P300), or 400 mL h-1 (P400) until loss of consciousness using bispectral index (BIS) monitoring in 72 adult patients. Change in blood pressure, induction time, and dose of propofol were compared among 3 groups.Results: The decreases in systolic and mean arterial pressure were statistically significant in the P200 group (P = 0.001, P =0.014 respectively). Systolic blood pressure decreased significantly as the infusion rate increased. Diastolic blood pressure did not change in either group. The duration of induction was shortest with 400 mL h-1 infusion rate (177 s in P200, 182 s in P300, 134 s* in P400,*P = 0.003) and the total propofol dose was significantly higher in these patients (2.32 mg kg-1 in P200, 2.64 mg kg-1 in P300 , 2.85* mg kg-1 in P400, *P = 0.012).Conclusion: The induction dose required for loss of consciousness increased with a faster rate of infusion while time for induction was shorter in P400 compared to P200 and P300, and the decrease in mean blood pressure was less after induction in P200. Propofol injection should be slow enough to prevent any hemodynamic deterioration in anesthesia induction.