Cardiopulmonary hemodynamics in patients with serious head injury

Cardiopulmonary hemodynamics after serious head injury were measured in eight patients to determine the relationship of these responses to intracranial pressure and alterations in pulmonary gas exchange. All patients had similar degrees of craniocerebral injury when assessed by the Glasgow Coma Scale, computerized tomographic scan, and initial intracranial pressure measurement. Intrapulmonary shunt fractions were elevated in all patients (range 11–29%) supporting the hypothesis that pulmonary dysfunction following isolated head injury is a distinct nosological entity. However, no correlation was found between level of intracranial pressure and any of the cardiopulmonary hemodynamic parameters studied. Patients surviving their injury initially showed a low cardiac index (2.56 ± 0.21 liters/min/M²) which subsequently became normal (3.77 ± 0.40 liters/min/M²). There was no evidence of increased pulmonary vascular resistance in these patients (95 ± 15 dyne-sec/ cm⁵). In contrast, patients dying of their injury generally had high pulmonary vascular resistance on admission (284 ± 74 dyne-sec/cm⁵) and a low cardiac index throughout their hospital course (1.87 ± 0.43 liters/min/M²). The cause of low cardiac index seen in this study is unknown. The abnormally high pulmonary vascular resistance in nonsurvivors may be a primary response of the pulmonary vasculature to serious head injury and reflect the severity of that injury.