Effectiveness of a manually controlled infusion scheme of propofol and alfentanil mixture for endotracheal intubation in hypertensive patients: in comparison with thiamylal and nifedipine plus thiamylal.

BACKGROUND: Bolus administration of propofol for induction causes hypotension, especially in elderly hypertensive patient. Carefully titrated infusion of propofol minimizes adverse effects, such as hypotension, and permits a rapid recovery of its central effects. The objective of this study was to investigate the effect of a manually controlled infusion scheme of propofol and alfentanil mixture on hemodynamic stability during induction and endotracheal intubation for hypertensive patient. At the same time, the effectiveness of this scheme was compared with two other induction regimens (thiamylal or nifedipine plus thiamylal).

METHODS: Sixty hypertensive patients undergoing orthopedic surgery were randomized into 3 groups (n = 20 per each group), None of the patients received premedication. Anesthesia was induced in group 1 (G1) with alfentanil 10 micrograms/kg. 30 s later, manual infusion of a mixture of propofol (10-12 mg/kg/h) and alfentanil (25 micrograms/kg/h) was performed for 2 min, followed by atracurium (5 mg) and propofol (1-1.5 mg/kg) as a bolus induction dose over 20 s, and then Suxamethonium (1.5 mg/kg) at 30-40 s later. Intubation was done while giving a continuous infusion of propofol and alfentanil. After intubation, the infusion rate was adjusted according to the blood pressure (BP) variation. Group 2 patients (G2) were induced with fentanyl (2 micrograms/kg), thiamylal (4-5 mg/kg), atracurium (5 mg) and succinylcholine (1.5 mg/kg). Induction of anesthesia in group 3 patients (G3) was the same as for G2, with additional sublingual nifedipine (1/2 capsule) 10 min prior to induction. Extra bolus dose of propofol (20 mg) or thiamylal (20 mg) was given at every 15 s if the systolic BP was still higher than 160 mmHg after induction by the above 3 regimens. The radial arterial pressure and electrocardiogram were continuously recorded for evaluation of hemodynamic changes.

RESULTS: Post-intubation peak mean arterial pressure (MAP) in G1 and G3 were below to awake baseline values, while MAP of G2 was significantly higher than over awake baseline level (p < 0.001). The lowest MAP of G3 at post-intubation period before surgical stimulation were significantly lower than those of G1 and G2 (p < 0.001). Peak tachycardiac response to intubation in G2 was significantly higher than G1 (p < 0.05). After intubation, the peak rate pressure product were significantly higher in G2 compared with that in G1 (p < 0.05) and G3 (p < 0.001).

CONCLUSIONS: The proposed manual infusion scheme of propofol and alfentanil mixture performed during induction and intubation attenuated the subsequent peak pressor response to incubation and reduced the hypotensive effect, in comparison to thiamylal or thiamylal plus nifedipine treatment, during post-intubation period. The same infusion scheme also attenuated the tachycardiac response to intubation.