Hemodynamic response to induction and intubation. Propofol/fentanyl interaction.

BACKGROUND

When given as an intravenous bolus for induction of anesthesia, propofol can decrease postintubation hypertension but can also create moderate to severe postinduction, preintubation hypotension. The addition of fentanyl usually decreases the postintubation hypertension but can increase the propofol-induced preintubation hypotension. The goal of the study was to determine the relation between propofol and fentanyl doses and the hemodynamic changes post-induction, preintubation and postintubation.

METHODS

Twelve groups of 10 patients, ASA physical status 1 or 2, first received fentanyl 0, 2, or 4 micrograms.kg-1 and then 5 min later received propofol 2.0, 2.5, 3.0, or 3.5 mg.kg-1 as an intravenous bolus for induction of anesthesia. Arterial blood pressure was continuously monitored. The trachea was intubated 4 min after propofol administration.

RESULTS

The mean decrease in systolic blood pressure after propofol was 28 mmHg when no fentanyl was given, 53 mmHg after 2 microgram.kg-1 of fentanyl (P < 0.05 vs. no fentanyl), and 50 mmHg after 4 micrograms.kg-1 (P < 0.05 vs. no fentanyl; no statistically significant difference 4 vs. 2 micrograms.kg-1). There was no statistically significant difference in hemodynamic response to intubation relative to propofol dose. Hemodynamic response to intubation was decreased by the administration of fentanyl; the mean increase of systolic blood pressure after intubation was 65 mmHg from preintubation value without fentanyl, 50 mmHg after 2 micrograms.kg-1, and 37 mmHg after 4 micrograms.kg-1 (P < 0.05 for 2 and 4 micrograms.kg-1 vs. no fentanyl and for 4 vs. 2 micrograms.kg-1). Hemodynamic changes postintubation were not statistically different with increasing doses of propofol.

CONCLUSIONS

Hemodynamic changes after induction with propofol or propofol/fentanyl, pre- or postintubation, are not modified when the propofol dose is increased from 2 to 3.5 mg.kg-1. Maximal hypotension preintubation occurs with a fentanyl dose of 2 micrograms.kg-1, whereas the magnitude of postintubation hypertension is significantly decreased with an increase in the fentanyl dose to 4 micrograms.kg-1.