Physiologic Aspects of porcine Hemorrhage. II. Alterations in Heart Rate and Arterial Pressure during Fifty Percent Blood Volume Loss in the Conscious Animal

摘要

A porcine animal model, designed to simulate physiologic characteristics of the combat casualty, was used to assess the effects of severe blood loss on the heart rate and arterial pressures in the absence of anesthesia or other interventions. Chronic catheters were placed surgically in the aorta, via the carotid artery, of 8 young domestic pigs. Seven to 9 days after surgery each animal was brought into the laboratory and the catheter was connected to a three-way stop-cock and a pressure transducer for blood removal and pressure recording. After 30 minutes of unrestrained and uninterrupted supine rest, control measurements were made. Thereafter, 50% of the estimated blood volume was removed progressively over a one-hour period. No physiological changes were seen until blood exceeded 10%. A transient increase in heart rate occurred at 20% loss, but subsequent rates were no different from control values. Systolic, diastolic, and mean arterial pressures decreased progressively between 20 and 50% blood loss; the respective values at 50% blood loss were 84 + or - 3.2, 31 + or - 3.2, and 49 + or - 2.8 mm Hg. Because of the functional similarities of the human and porcine cardiovascular systems, studies of severe hemorrhage in the recumbent conscious pig may provide reliable physiological information which will be useful in recognizing the consequences of massive hemorrhage in humans.