Effect of sodium nitroprusside on cerebral haemodynamics during cross-clamping of the descending thoracic aorta in pigs

Objective: To assess the effect of sodium nitroprusside on cerebral haemodynamics during cross-clamping of the descending thoracic aorta in pigs. Design: Non-randomised controlled animal study. Setting: University hospital, Norway. Material: 17 Pigs. Interventions: Cross-clamping of the descending thoracic aorta for 30 minutes. In 8 pigs sodium nitroprusside was given to prevent proximal hypertension (sodium nitroprusside group); 9 pigs were given no sodium nitroprusside (control group). Main outcome measures: Intracerebral pressure, sagittal sinus pressure, cerebral flux, and internal carotid artery blood how. Results: Intracerebral pressure, sagittal sinus pressure, and cerebral flux increased in both groups during cross-clamping of the descending thoracic aorta. There were no differences between the groups in these variables despite significantly lower mean proximal aortic pressure in the sodium nitroprusside group. Conclusions: Sodium nitroprusside did not affect intracerebral pressure, sagittal sinus pressure, or cerebral flux during cross-clamping of the descending thoracic aorta. Increased cerebral blood flow rather than venous congestion is the most likely cause of increased intracranial pressure during cross-clamping of the descending thoracic aorta.