[Behavior of GH and prolactin during enflurane anesthesia and neuroleptoanesthesia in man]

The present study was designed to investigate the effects of neuraleptanesthesia (NLA) and enflurane (Ethane) anesthesia on plasma levels of growth hormone (GH) and prolactin (PRL) in man. A total of 18 patients aged between 20 and 65 years scheduled for elective open-heart surgery were divided in two groups. In the first group (9 patients) general anaesthesia was induced with sodium thiopental (TPS) (3-5 mg/kg) and was maintained with enflurane administered with an inspired concentration of 1.5% in nitrous oxide (2 litres/min) and oxygen (2 litres/min). In the second group (9 patients) anaesthesia was induced with dihydrobenzopyridol (BPS) (0.1-0.2 mg/kg), fentanyl (5-8 gamma/kg) and TPS (3-5 mg/kg) and was maintained with fentanyl (0,65 mg in average). The patients had neither hepatic, renal or endocrine disease nor did they have a history of steroid therapy. All subjects received atropine (0.01 mg/kg) and diazepam (0.2 mg/kg) i.m. 2 hours before induction of anaesthesia. Blood samples for GH and PRL was collected before induction of anaesthesia (0) and at 30, 60, 90 and 120 minutes after induction: the 90' sample was taken immediately after sternal incision. The sampling was stopped at the start of the cardiopulmonary by-pass. A significative reduction of GH at 60' and of PRL at 30' was observed in both groups. Surgical stress at 90' does not evoke a significant increase of PRL and GH levels in both groups. In conclusion NLA and enflurane induced a decrease of GH and PRL plasma levels; in both groups the anaesthetic agents, at the dosage used during anaesthesia, blocked the response of these hormones to the surgical stress likely due to a block of the hypothalamic-pituitary response.