PROSTAGLANDIN-E1 AND CARBON-DIOXIDE RE-ACTIVITY DURING CEREBRAL ANEURYSM SURGERY

The purpose of this study was to evaluate the effect of prostaglandin E1 (PGE1) on CO2 reactivity during cerebral aneurysm surgery in 37 patients under neuroleptoanaesthesia (NLA). The patients were divided into two groups based on the timing of surgery (A: late surgery, B: early surgery). In the early surgery group, aneurysm surgery was performed within three days of subarachnoid haemorrhage (SAH) and in the late surgery group surgery was performed more than four days after SAH. Presurgical neurological status was worse in the early surgery group than in the late surgery group (P < 0.01). Local cerebral blood flow (LCBF) measurements were made using a thermal gradient blood flow meter. Hypotension was induced by PGE1 administration at an initial dose of 0.1-mu-g.kg-1.min-1 and adjusted to maintain the mean arterial pressure (MAP) at about 70 mmHg. The CO2 reactivity was calculated by the % change in LCBF divided by the change in PaCO2 (%DELTA-CBF/DELTA-PaCO2 (%.mmHg-1)). LCBF, heart rate and mean arterial blood pressure were measured during and after PGE1 infusion. Carbon dioxide reactivity was measured before, during and after PGE1 administration. The LCBF did not change throughout the study but CO2 reactivity was greater in Group A (before hypotension: 2.74 +/- 0.85 % .mmHg-1, during hypotension: 2.54 +/- 0.73 % .mmHg-1, after hypotension: 2.59 +/- 1.17 % .mmHg-1) than in group B (before hypotension: 1.54 +/- 0.57 % .mmHg-1, during hypotension: 1.56 +/- 0.59 % .mmHg-1, after hypotension: 1.49 +/- 0.42 % .mmHg-1) (P < 0.01). Outcome which was graded by Glasgow Outcome Scale at discharge, was better in Group A (P < 0.05). There were close correlations between presurgical neurological status and outcome (rs = 0.743 P < 0.01) and between presurgical neurological status and CO2 reactivity before (rs = 0.558, P < 0.01), during (rs = -0.636, P < 0.01) and after hypotension (rs = -0.773, P < 0.01). These findings suggest that PGE1 maintains LCBF and CO2 reactivity, and CO2 reactivity and outcome are correlated closely with the presurgical neurological status.