An effect of trauma on human cardiovascular control: baroreflex suppression.

Survival from injury depends on the interaction between the patient's own homeostatic responses and treatment given. The function of the principal homeostatic reflex of the cardiovascular system, the arterial baroreflex, was studied in 22 healthy controls and in 21 moderately injured patients (ISS range, 9 to 17; median, 9) using suction stimulation of the carotid sinus baroreceptors. When compared to controls, marked baroreflex suppression was evident 3 hours after injury (p less than 0.05), at 3 days after injury (p less than 0.001), and even 15 days after injury (p less than 0.05, all Wilcoxon rank sum test). Partial recovery of baroreflex function occurred between 3 and 15 days after injury (p less than 0.005, all Wilcoxon signed rank test) and was complete by 5 months after injury. The suppression of baroreflex activity was accompanied by a "fixed" rise in heart rate and a rise in systolic blood pressure. This study has shown that moderate injury results in a profound and prolonged suppression of baroreflex function. Further advances in the resuscitation and critical care of the injured may need to take account of such derangements of cardiovascular physiology.