Effects of Induced Hypotension and Hypertension on Cortical Arterial Pressure and Anastomotic Blood Flow during STA-MCA Anastomosis

Abstract

The effects of intraoperative induced hypotension and hypertension on cortical arterial pressure (CAP) and anastomotic blood flow (AF) were investigated for determination of the autoregulatory potential in patients who undergo superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis. Hypotension and hypertension were produced by intravenous injection of trimethaphan camsylate and phenylephrine hydrochloride, respectively. The mean CAP, AF, and systemic arterial blood pressure (SABP) were 63 mmHg, 25 ml/min, and 102 mmHg, respectively, on the average. The effects of hypotension and hypertension were analyzed by the ratios of Δmean AF to Δmean SABP and Δmean CAP to Δmean SABP. In induced hypertension, Δmean CAP to Δmean SABP and Δmean AF to Δmean SABP were 0.67±0.40 and 0.21±0.37, respectively. In induced hypotension, Δmean CAP to Amean SABP and Δmean AF to Δmean SABP were 0.59±0.40 and 0.07±0.15, respectively. Eight patients exhibited a failure of autoregulation; their mean CAP, AF, and SABP were 35 mmHg, 37 ml/min, and 95 mmHg, respectively, on the average. These data indicate that autoregulation of STA-MCA anastomotic blood flow is excellent in most cases. In some instances, however, autoregulatory dysfunction was observed, and this no doubt plays an important role in temporary neurological deterioration after STA-MCA anastomosis.