Circulatory effects of haemorrhage during sodium nitroprusside induced hypotension. A study in the rat

The haemodynamic changes induced by acute moderate blood loss were investigated in rats during normotensive halothane anaesthesia and during sodium-nitroprusside-induced hypotensive anaesthesia, respectively. Following haemorrhage in the normotensive group, mean arterial blood pressure, heart rate and left cardiac work decreased. Cardiac output was reduced non-significantly. Blood flow was redistributed to favour cerebral, coronary, renal and hepatic circulation, mainly at the expense of blood flow to the carcass. Following haemorrhage in the hypotensive group, cardiac output increased significantly. Mean arterial pressure, heart rate and left cardiac work were unchanged. Absolute values for cerebral, coronary, renal and hepatic blood flow were maintained or even increased, while blood flow to the carcass was unchanged.