The stress response to induced hypotension for cerebral aneurysm surgery: a comparison of two hypotensive techniques.

Plasma epinephrine (PE), plasma norepinephrine (PNE), plasma renin activity (PRA), mean arterial pressure (MAP) and heart rate (HR) were measured before, during and after induced hypotension in two groups of patients undergoing cerebral aneurysm surgery. In Group I isoflurane was used to maintain anaesthesia and induce hypotension. Mean PE fell significantly during hypotension and remained reduced after hypotension, mean PNE remained unchanged, while mean PRA rose slightly but not significantly during hypotension, falling again after hypotension. In Group II halothane was used to maintain anaesthesia and sodium nitroprusside to induce hypotension. During anaesthesia and surgical stimulation PNE and PRA were significantly greater compared to Group I. Mean PE, PNE and PRA all rose during hypotension and remained elevated after hypotension. The rise in PNE and PRA was statistically significant. After hypotension the MAP in Group II was significantly higher when compared to Group I. There was no significant change in HR during the study in either group. In conclusion, isoflurane-induced hypotension with isoflurane anaesthesia unlike sodium nitroprusside-induced hypotension with halothane anaesthesia attenuated the stress response.

Fatality due to massive overdose of sodium valproate.

A 40-year-old woman admitted after a massive overdose of sodium valproate was found to have a serum valproate level of 18,900 mumol/1 which is the highest ever reported. She underwent cardio-respiratory failure, bone marrow suppression and neurological depression, subsequently dying. On post-mortem there was haemorrhagic pancreatitis but no histological evidence of hepatotoxicity. Valproate levels measured in various post-portem tissues and fluids indicated a high level in bile (21,375 mumol/1) suggesting that enteral administration of activated charcoal might be of some benefit by decreasing enterohepatic circulation of the drug.

Profound reduction in morphine clearance and liver blood flow in shock.

In six patients with septic shock apparent liver blood flow was significantly reduced compared with two patients restudied on recovery from shock and a group of four matched unshocked patients undergoing intensive care (287 +/- 23 ml/min vs 870 +/- 164 ml/min; mean +/- SEM). In the shocked patients the elimination half-life of morphine was significantly prolonged (13.2 +/- 3.5 h vs 5.9 +/- 1.4 h; mean +/- SEM) and the systemic clearance of morphine reduced by 53%, in comparison with the non-shocked patients. In both groups, morphine elimination was markedly delayed compared with previously reported observations in normal subjects and surgical patients. Care should be exercised with the use of drugs with a high hepatic extraction ratio in shocked patients.