Cardiovascular changes during controlled blood loss and replacement.
Changes in central venous pressure, systolic arterial pressure and pulse rate were recorded in 31 patients undergoing surgery involving withdrawal of 1 litre of blood and subsequent transfusion. Central venous pressure gave immediate and consistent indications of blood loss and replacement but blood volume changes could not be correlated numerically with central venous pressure. No difference was found between patients anaesthetised using spontaneous ventilation with halothane and intermittent positive pressure ventilation.