ANESTHESIA AFFECTS PLASMA-CONCENTRATIONS OF VASOPRESSIN, VONWILLEBRAND-FACTOR AND COAGULATION FACTOR-VIII IN CARDIAC SURGICAL PATIENTS

Operative stress may affect haemostatic mechanisms through hormonal systems. As the endocrine stress response to surgery may be modulated by anaesthesia, we have altered stress hormone concentrations by using either opioid or inhalation based anaesthesia to study haemostatic mechanisms in cardiac surgical patients. Thirty patients undergoing coronary artery surgery were allocated randomly to receive fentanyl (non-stress group) or enflurane (stress group) as the main anaesthetic agent. After cardiopulmonary bypass (CPB), plasma arginine vasopressin (AVP) concentrations were significantly (P < 0.001) greater in the stress group (81.8 (46.9-142.9) pg ml-1, mean with 95% confidence limits) than in the non-stress group (5.8 (3.3-10.2) pg ml-1). Plasma noradrenaline and adrenaline concentrations increased similarly in both groups after CPB. Plasma concentrations of both von Willebrand factor (stress: 1.56 (1.33-1.79) iu ml-1; non-stress: 1.00 (0.76-1.25) iu ml-1) and coagulation factor VIII: C (stress 1. 15 (0.87-1.44) iu ml-1; non-stress: 0.69 (0.55-0.80) iu ml-1) were significantly (P < 0.01) greater in the stress group than in the non-stress group after CPB, The results indicate that there is a temporal relationship between the increased plasma concentrations of AVP and von Willebrand factor and factor VIII: C. It is not clear if this indicates a causal relationship. Ho we ver, variable stress control by anaesthesia may modify haemostasis in cardiac surgical patients.