Uncompensated Blood Loss Is Not Tolerated During Acute Normovolemic Hemodilution in Anesthetized Pigs

NT-ProBNP and cardiac troponin I in virulent canine babesiosis

“…Below these levels of critical oxygen delivery, signs of circulatory collapse and shock develop. In pigs signs of shock include reduction in cardiac output, increased central venous pressure, bradycardia, decreased mixed venous saturation, arterial hyperlactatemia, and hypotension (Schou et al, 1998). In this study a reduction in cardiac output (as determined by FS), bradycardia, hyperlactatemia, or hypotension was not evident, making shock an unlikely cause.…”

Subcutaneous Po2 as an index of the physiological limits for hemodilution in the rat

“…Although surprising, our finding that MABP progressively fell when Hct dropped below 24% is consistent with observations in other animal species and humans. In humans (11,40,64) and animals (2,48,63), MABP rarely falls until Hct drops below 20 -25%. Because MABP is normally a regulated variable, it would be expected that the normal homeostatic response would result in an increase in peripheral resistance and/or CO to maintain MABP, the driving force for organ blood flow.…”

“…Because it is well known that CO during exercise is capable of increasing by as much as fivefold, the small 40% increase observed in the present study may reflect an intrinsic limitation of cardiac function. The adverse influence of hypovolemia on tolerance for hemodilution is well documented (3,30,48) and is a complication in studies that do not accomplish maintenance of the vascular volume in the exchange-transfusion process, because CO may be preload limited. It is unlikely that the increase in CO was limited by inadequate circulatory volume and preload in the present study, because the exchange of plasma was 1.5 times the volume of blood removed.…”

The Limits of Acute Anemia

“…In the case of hypovolemia, peripheral vasodilation, one of the main compensatory mechanisms of acute anemia, is counteracted. This prevents the combination of acute anemia and acute hypovolemia from being compensated as well as acute anemia alone [30]. Lastly, none of these animal studies investigated the long-term outcome of such severe anemia.…”