Vasopressin and haemostatic responses to inguinal hernia repair under local anaesthesia

Major abdominal surgery is accompanied by intra-operative increases in factor VIII (FVIII), plasminogen activator activity (PAA) and fibrinopeptide A (FPA). Vasopressin (aVP) released during surgery mediates some of the effects but the mechanisms involved in this response are unclear. To investigate the role of the operative procedure, 20 subjects were studied during inguinal hernia operation under local anaesthesia. Venous blood samples were taken for FVIII coagulant activity (FVIII:C), euglobulin clot lysis time (ECLT), FPA, crosslinked FDPs (XL-FDP) and a VP. In six patients, aVP rose from (median) 0.5 to 38.3 pg/ml at bowel manipulation and fell to 4.1 pg/ml post-operatively. PAA rose from 33 units to 377 and 316 units (P less than 0.01), FVIII:C from 1.58 to 2.4 IU/ml (P less than 0.01) and FPA from 5.0 to 6.8 and 11.0 pmol/ml intra-operatively (P less than 0.002). XL-FDP rose from a median value of 34 ng/ml pre-operatively to 230 ng/ml post-operatively. In 14 patients plasma aVP levels remained constant and both FVIII:C and PAA remained unchanged. FPA rose from 2.6 pmol/ml to 5.9 pmol/ml intra-operatively (P less than 0.05) and XL-FDP fell from 110 to 60 ng/ml. Between groups, the changes were significantly different for FVIII:C (P less than 0.05) and PAA (P less than 0.03) with no differences in blood pressure, pulse or symptoms. These results support the hypothesis that aVP secretion during surgery mediates increases in FVIII and PAA. FPA tended to be higher in the aVP secreting group which indicates that aVP mediated activation of coagulation results in a hypercoagulable state.