The effect of haemorrhage on venous return and regional blood flow in the anaesthetized cat

Abstract

SUMMARY1. In cats under pentobarbitone anaesthesia, a venous long-circuit technique was used to measure the blood flows in the superior vena cava and the hepatic, renal and iliac segments of the inferior vena cava. The sum of these flows gave the venous return (minus coronary and bronchial flows).2. In these preparations, the mean venous return was 130 ml./kg. Of this 28 % came from the superior vena cava and 37 % from the hepatic, 23 % from the renal and 12 % from the iliac segments of the inferior vena cava.3. After haemorrhage, the flows from all the venae cavae segments decreased. The quantitative changes varied with the particular cat, the degree and duration of the haemorrhage and whether the animal had been subjected to a previous haemorrhage.4. The proportion of the reduced venous return draining from the superior vena cava and the hepatic segment increased, that draining from the renal and iliac segments decreased. Vasoconstriction occurred in all vascular beds, but was greatest in the kidney and hind limbs. Thus the blood flow through the head and liver was partially maintained at the expense of that through the kidneys and hind limbs.5. Autoregulation of blood flow in the kidneys was usually seen immediately after the first removal of blood but with the onset of renal vasoconstriction it was reduced or abolished for the remainder of the experiment.

Effects of Hemorrhage on Regional Blood Flow Distribution in Dogs and Primates

“…There are several possible explanations for the discrepancy between the conclusion of previous investigations, indicating intense renal vasoconstriction with hemorrhage (18)(19)(20)(21)(22)(23)(24)(25)(26)(27), and those in the present one, demonstrating sparing of the renal bed. Three important features of the present investigation were (a) renal blood flow was measured in the conscious animal, (b) these measurements were instantaneous and continuous, and (c) hemorrhage was not severe or prolonged, i.e., hemorrhagic shock did not develop.…”

“…While measurements were recorded continuously during hemorrhage, two points were chosen to compare with control values; the first occurred before a reduction in arterial pressure, which occurred after 14±2 ml/kg of hemorrhage and is designated as the mild nonhypotensive hemorrhage response, while the second point was chosen after a sustained [20][21][22][23][24][25][26][27][28][29][30] ied hypoten-iliac flow had fallen by 58±5% to 46±4 ml/min and iliac resistance had risen from 0.88+0.05 to 1.72±0.11 -onary blood mm Hg/ml/min. These changes were all significant and transi-(P < 0.01) ( %) resistances were significantly less than without blockade (P < 0.01).…”

“…In contrast, the concept that the renal bed responds to hemorrhage with constriction is widely accepted (1, 2, 18-27). In fact, there are several studies which indicate the renal bed has the most intense constriction of all peripheral beds studied (25,26).…”

The effects of adrenaline and noradrenaline on venous return and regional blood flows in the anaesthetized cat with special reference to intestinal blood flow

“…The details of the technique have been described previously (Greenway & Lawson, 1966). The venae cavae were divided into four segments and the blood flow from each was separately long-circuited and measured by timing the collection of 10 ml.…”

“…It is therefore difficult to assess to what extent these sub-580 C. V. GREEN WA Y AND ANNE E. LAWSON stances cause a redistribution of the regional blood flows, although Barcroft & Swan (1953) attempted this on the basis of the results available for man. The problem has been re-investigated using a technique which allows measurement of the flows from four regions of the cat (Greenway & Lawson, 1966). To assess whether the responses to adrenaline and noradrenaline were modified by reflexes involving the brain, the infusions were repeated after the administration of a spinal anaesthetic into the cisterna magna.…”