EFFECT OF SODIUM-NITROPRUSSIDE ON CEREBRAL HEMODYNAMICS DURING CROSS-CLAMPING OF THE DESCENDING THORACIC AORTA IN PIGS

Objective: To assess the effect of sodium nitroprusside on cerebral ha emodynamics during cross-clamping of the descending thoracic aorta in pigs. Design: Non-randomised controlled animal study. Setting: Univers ity hospital, Norway. Material: 17 Pigs. Interventions: Cross-clamping of the descending thoracic aorta for 30 minutes. In 8 pigs sodium nit roprusside was given to prevent proximal hypertension (sodium nitropru sside group); 9 pigs were given no sodium nitroprusside (control group ). Main outcome measures: Intracerebral pressure, sagittal sinus press ure, cerebral flux, and internal carotid artery blood how. Results: In tracerebral pressure, sagittal sinus pressure, and cerebral flux incre ased in both groups during cross-clamping of the descending thoracic a orta. There were no differences between the groups in these variables despite significantly lower mean proximal aortic pressure in the sodiu m nitroprusside group. Conclusions: Sodium nitroprusside did not affec t intracerebral pressure, sagittal sinus pressure, or cerebral flux du ring cross-clamping of the descending thoracic aorta. Increased cerebr al blood flow rather than venous congestion is the most likely cause o f increased intracranial pressure during cross-clamping of the descend ing thoracic aorta.