Comparison of effects of remifentanil, alfentanil and fentanyl on cardiovascular responses to tracheal intubation in morbidly obese patients

Background and objective: The effects of remifentanil, alfentanil and fentanyl were compared on cardiovascular responses to laryngoscopy and endotracheal intubation in morbidly obese patients. Methods: Eighty morbidly obese ASA I-II patients were included in the study. Patients were randomly divided into four groups to receive either 1 mug kg(-1) fentanyl (Group F), 10 mug kg(-1) alfentanil (A), 1 mug kg(-1) followed by an infusion of 0.5 mug kg min(-1) remifentanil (R) or saline (P). The patients corrected weight was used to calculate the drug doses. Body mass indices (range) were: 54.3 +/- 737 (49-78.4), 55.67 +/- 7.44 (48.5-78.4), 53-17 +/- 5.36 (48.1-63.2), and 56.3 +/- 6.09 (46.6-67.7) kg m(-2), in Groups F, R, A and P respectively. Systolic, diastolic and mean arterial pressures and heart rate were measured non-invasively at three time points, which were 2 min before induction, 2 min after induction and 2 min after endotracheal intubation. Results: After induction of anaesthesia, arterial pressures decreased significantly in all groups, but the decrease was more pronounced in Groups A and R. After induction, heart rate decreased significantly in all groups except in Group P. After intubation, haemodynamic responses were similar in the remifentanil, fentanyl and alfentanil groups and were within normal limits. In Group P, arterial pressures and heart rates were significantly higher. Conclusions: Alfentanil, fentanyl and remifentanil in the doses described had similar, effects in controlling the haemodynamic response to tracheal intubation in ASA I-II morbidly obese patients.