CEREBRAL HEMODYNAMICS DURING THORACICABDOMINAL AND THORACOABDOMINAL AORTIC-ANEURYSM REPAIR

Objective: To investigate cerebral haemodynamics during operations for thoracic and thoracoabdominal aortic aneurysms. Design: Prospective c linical study Material: 10 patients operated on consecutively with res ection for thoracic (5) or thoracoabdominal aortic (5) aneurysms. Meth ods: Blood flow velocity of the middle cerebral artery was measured th rough a temporal approach using a TC Doppler with a 2 MHz probe. Recor dings were made during induction of anaesthesia and performed continuo usly before, during and after cross-clamping of the aorta. Results: Fo llowing 20 min. of aortic cross-clamping blood flow velocity of the mi ddle cerebral artery increased from 44 to 55 cm/s (p < 0.01). A furthe r increase to 69 cm/s (p < 0.01) was observed 5 min after declamping. The pulsatility index averaged 0.74 increasing to 1.21 (p < 0.05) at c lamping and 0.87 (p < 0.05) after declamping. Conclusion: There was an increased blood flow velocity of the middle cerebral artery during cr oss-clamping of the descending thoracic aorta in patients operated on for thoracic and thoracoabdominal aortic aneurysms. This increase in c erebral blood flow and blood volume could explain the acute increase i n cerebrospinal fluid pressure observed during cross-clamping of the t horacic aorta.