Haemodynamic changes in patients with severe head injury.

Haemodynamic studies were carried out in 12 patients who had sustained severe head injury. Radial artery pressure(AP), pulmonary artery pressure(PAP), central venous pressure(CVP), and pulmonary wedge pressure(PAWP) were directly measured. Heart rate was monitored from the ECG, and cardiac output (CO) was measured intermittently by the thermodilution technique. Arterial and mixed venous blood samples were withdrawn simultaneously for measurement of PH, PCO2, PO2, and oxygen saturation. Additional cardiovascular data were calculated from standard formulae. The haemodynamic pattern in these head-injured patients was characterized by high cardiac index, low systemic vascular resistance, moderately high systemic pressure and heart rate, high pulmonary artery pressure and wedge pressure, and normal stroke index. These findings may be the result of autonomic or adrenergic stimulation by the injured brain.