Effects of intravenous nitroglycerin combined with dopamine on intracranial pressure and cerebral arteriovenous oxygen difference in patients with acute subarachnoid haemorrhage.

Abstract

The effects of intravenous nitroglycerin (NTG) combined with dopamine on intracranial pressure (ICP) and cerebral arteriovenous oxygen difference (AVDO2) were studied in 11 patients with acute subarachnoid haemorrhage (SAH). The study was performed on Days 1 to 3 of SAH after aneurysmal clipping. Treatment consisted of an intravenous drip infusion of NTG in increasing incremental doses of 0.5, 1.0, 1.5, 2.0, and 2.5 micrograms/kg/min at one-hour intervals. Dopamine (5 to 10 micrograms/kg/min) was also given concurrently to maintain systemic blood pressure. ICP values before NTG administration ranged from 7 to 24 mmHg (mean. 11.91 +/- 5.30 mmHg). ICP began to increase immediately after the administration of NTG 0.5 microgram/kg/min and peaked at 14.64 +/- 5.93 mmHg 10 minutes after onset of infusion. Thereafter, ICP gradually returned to pretreatment levels. Increasing the dose of NTG failed to induce further significant rises in ICP. Mean AVDO2 before NTG administration was 4.69 +/- 0.62 ml/dl. This parameter showed no significant change during NTG infusion, although cerebral perfusion pressure decreased to between 75% to 94% of the control value after NTG administration. These results indicate that continuous NTG infusion combined with dopamine does not have adverse effects on ICP (the ICP increase is minimal and transient) and may even have beneficial effects on CBF in patients with acute SAH.