Haemodynamic defect in patients with severe head injury

Haemodynamic studies were made in 34 patients with severe head injury. The changes of cardiac output were noteworthy and correlated well with the clinical course and the prognosis of the patients. Marked systemic hypotension at the moment of brain death was mainly caused by the decrease of cardiac output. At this moment, peripheral resistance fell only to normal limits from the raised level. In the patients who survived, the cardiac output increased in proportion to the respiratory insufficiency, that is, the increased A-aDO₂ and Q?s/Q?t. The increase of oxygen consumption was also accompanied by an increased cardiac output, but in the patients with the severest head injury who died, the cardiac output remained low. It failed to respond to increased A-aDO₂ and Q?s/Q?t, and oxygen consumption remained low.