ENHANCED HEART-RATE RESPONSE TO HEMORRHAGE BY ILEUS IN THE PIG

Effects of ileus on cardiovascular and hormonal responses to haemorrha ge were evaluated in 10 anaesthetized pigs. Ileus was induced and the bleeding sequence repeated on the following day. Before ileus, a resti ng heart mte (HR) of 105 (range 83-140) beats min-1 remained unchanged until haemorrhage amounted to 15 % of the blood volume. With a blood loss of 28 % HR increased to a maximum of 162 (126-245) beats min-1. I n contrast, ileus increased HR upon initiation of haemorrhage from a s imilar resting value to a maximum of 200 (152-250) beats min-1 (P < 0. 0005). There were neither statistical differences in mean arterial pre ssure, cardiac output, central venous pressure, thoracic electrical im pedance, pulmonary arterial mean pressure, pulmonary wedge pressure, p ulmonary and systemic vascular resistances, nor in plasma concentratio ns of dopamine, adrenaline, vasopressin and aldosterone during haemorr hage before and after ileus. Plasma noradrenaline increased more with haemorrhage after than before ileus: from 2.8 (1.2-5.0) to 13 (2.3-59. 0) vs. 3.0 (1.5-4.2) to 3.6 (2.7-17.5) nmol l-1 (P < 0.005). Also, the pancreatic polypeptide response to haemorrhage was enlarged with ileu s (29 (0-60) to 90 (45-145) vs. 23 (0-64) to 57 (27-106) pmol l-1 (P < 0.005)). No significant differences could be detected in cardiovascul ar and hormonal responses to haemorrhage before and after a sham-opera tion in three pigs. Results demonstrate an immediate and enhanced HR r esponse to haemorrhage in the pig with ileus, reflected in sympathetic activation as indicated by plasma noradrenaline.