[Blood volume in aorto-femoral bypass operation. Effects of continuous thoracic epidural-, halothane- or neuroleptanesthesia].

49 patients with obliterative arteriosclerotic disease of aortic or iliac artery were tested with three different types of anaesthesia, epidural, halothane, and neuroleptanaesthesia. A normal blood volume was found preoperatively in these patients, i.e. of 75.8 +/- 14.9 ml/kg weight. Connections between blood volume and age or factors of risk were not traced. A patient with a-v fistula showed an obvious increased blood volume (120.2 ml/kg). Intraoperatively the blood volume varied widely during the different types of anaesthesia: while the blood volume increased in epidural anaesthesia (+17%) and remained unchanged by halothane (+1%), it decreased at the same volume load during neuroleptanaesthesia (-17%). A clear connection between changes of cardiac output and changes of the filling potential of the heart (cvp x bv) was found during epidural anaesthesia (r = 0.93). There was no functional connection in the neurolept group (r = -0.08). With halothane changes of filling potential correlated negatively with changes in cardiac output (r = 0.72). A connection between changes of the blood volume and the central venous pressure is evident only in the epidural group (r = 0.59). At the same time these reactions are dependent on the extent of the individual alterations of the vegetative tonus by the epidural block. Those individual changes are even more evident under halothane (r = 0.32) and especially neuroleptanaesthesia (r = 0.28). Therefore we question the control of blood volume by measurement of the central venous pressure for these patients.