PHOENIX, ARIZ. — Intravenous nicardipine can reduce blood pressure by 15%–20% without impairing blood supply to the brain in hypertensive emergencies, preliminary results from an ongoing case-control study suggest.
Results so far suggest nicardipine therapy might even improve cerebral oxygenation (PbrO2) in ischemic patients, reported study investigator Varun Puri, M.D. “There was no reduction in oxygen delivery to the brain despite significant reduction in [the fraction of inspired oxygen],” he said at a meeting sponsored by the Society of Critical Care Medicine.
Dr. Puri presented data on 17 patients with acute neurologic disorders, 11 of whom were women. The patients' average age was 57 years, and pathologies included seven subarachnoid hemorrhages, four traumatic brain injuries, three intracerebral hemorrhages, two arteriovenous malformations, and one case of anoxia.
The patients had 36 episodes of hypertensive emergency during the study: 11 from acute cardiovascular syndrome, 14 postoperatively, and 11 after trauma. The nicardipine dose, titrated as clinically indicated to lower blood pressure, ranged from 2.5 mg to 15 mg per hour. The duration of treatment ranged from 12 hours to 10 days.
Dr. Puri reported that systolic blood pressure fell from 175 mm Hg pretreatment to 143 mm Hg at 8 hours after treatment, diastolic blood pressure decreased from 84 mm Hg to 69 mm Hg, and mean arterial blood pressure dropped from 114 mm Hg to 95 mm Hg. All the changes were statistically significant.
Brain tissue monitoring over an 8-hour period showed no significant changes in intracranial pressure or partial brain tissue oxygenation (PbtO2). Fraction of inspired oxygen (FiO2) fell from 0.72 to 0.62, a statistically significant difference.
In six patients presenting with cerebral hypoxia, average PbtO2 was 10.4 mm Hg before treatment with nicardipine, a specific arterial dilator. By 4 hours post treatment, oxygenation had increased to 20.4 mm Hg. At 8 hours, it was 22.2 mm Hg, a statistically significant change.
One severe adverse event was reported: a case of hypotension that responded quickly to a reduction in the nicardipine dose, Dr. Puri said. Five patients eventually required oral antihypertensive agents, and three went on to β-blockers, he said. None had been on β-blockers before the trial, and patients taking two or more agents for hypertension had also been excluded.
The investigators are continuing to enroll patients, said Dr. Puri, of Creighton University Medical Center in Omaha, Neb. Integra LifeSciences Corp., maker of the Licox brain tissue oxygen monitoring system, provided funding for the study.