[The effect of nifedipine and fentanyl on changes in the circulatory reaction to endotracheal intubation].

UNLABELLED Recommendations for prevention of hypertension and tachycardia during the induction of anesthesia include the use of fentanyl and antihypertensive drugs and superficial anesthesia of the throat. Nifedipine has been used to treat acute hypertension and in many cases it has proved superior to other antihypertensive drugs. The present study was designed to find whether prophylactic injection of nifedipine alone or in combination with fentanyl can prevent cardiovascular responses during endotracheal intubation. METHODS A total of 140 female patients (ASA groups I or II) with no history of arterial hypertension were randomly allocated to 7 groups: group K was the control group, in which patients received only saline solution; patients in groups 0,1F; 0,2F; 0,3F received 0.1, 0.2 or 0.3 mg fentanyl, respectively; those in group 1,0N, 1 mg nifedipine; those in group 0,5N + 0,1F, 0.5 mg nifedipine, plus 0.1 mg fentanyl; and those in group 1,0N + 0,1F 1 mg nifedipine plus 0.1 mg fentanyl. Blood pressure and heart rate were measured at 1 min intervals. After estimation of control values the prophylactic drug or combination of drugs was injected. Anesthesia was induced in the conventional manner. Plasma concentrations of epinephrine and norepinephrine were analyzed before intubation and at 5, 30 and 60 min intervals after intubation. Side-effects, especially respiratory depression and arrhythmia, were carefully recorded. RESULTS In group K only systolic BP increased significantly after intubation. In the other groups the peak systolic blood pressure was not statistically different from the preinjection values. Diastolic BP increased significantly after intubation in all but two groups: in group 0,3F and in group 1,0N + 0,1F there was no significant difference in diastolic BP compared with the control values. The heart rate increased significantly in the control group after intubation as well as in groups 0,1F and 0,2F. In patients receiving 0.3 mg fentanyl there was no change in HR after intubation. Administration of 1 mg nifedipine alone (group 1,0N) or in combination with 0.1 mg fentanyl (group 1,0N + 0,1F) caused tachycardia even before intubation, whereas the combination of 0.5 mg nifedipine and 0.1 mg fentanyl did not result in a significant increase of HR following intubation. In all groups, epinephrine concentrations were significantly lower 5 min after intubation. A return to the control values was observed after 60 min in all groups except group 0,1F. Serum concentrations of norepinephrine were lower 5 min after intubation in all groups and were still low in groups 0,1F , 0,2F, 0,5N+0,1F and 1,0N+0,1F up to 60 min after intubation. Side-effects and adverse effects were checked for in the present study. An increase in heart rate was observed during induction in almost every group. More pronounced changes were recorded in groups 1,0N and 1,0N+ 0,1F receiving 1 mg nifedipine.(ABSTRACT TRUNCATED AT 400 WORDS)