The use of calcium antagonists to treat intra-operative hypertension--evaluation of efficacy and safety of a new dihydropyridine derivative, intravenous isradipine, during abdominal surgery.

Twenty-three patients who developed intraoperative hypertension (mean arterial pressure greater than 110 mmHg) during abdominal surgery under balanced general anaesthesia were randomly assigned to two groups. The isradipine group (n = 12) received 0.5 mg of isradipine, and the placebo group (n = 11) received 10 ml of isradipine solvent over a 5-min period in a blind manner. Arterial pressure was recorded 12 min after the injection was started. If the mean arterial pressure had not decreased by at least 10% at 12 min, patients received in an open manner 0.5 mg of isradipine. None of the patients in the isradipine group received isradipine in an open manner, in contrast with nine of the 11 patients in the placebo group (P less than 0.0001, Fisher's exact test). During both the blind period and the open trial, isradipine induced a 40% decrease in systolic, diastolic, and mean arterial pressures within the first two min of infusion. Arterial pressure remained below the pre-isradipine injection values for at least 45 min. Transient hypotension (mean arterial pressure less than 70 mmHg) was noted in 6/21 patients (29%). Mean heart rate remained statistically unchanged during the decrease in arterial pressure in both groups, but a tachycardia (increase in heart rate greater than 20 beats min-1) was noted in 4/21 patients (19%). This study indicates that intravenous isradipine is an effective therapy with sustained efficacy for intraoperative hypertension during abdominal surgery. The safety of its use needs a close monitoring of arterial pressure.