Effects of haemoglobin-based oxygen carrier Hemoglobin glutamer-200 (bovine) on intestinal perfusion and oxygenation in a canine hypovolaemia model

The objective of this investigation was to study the effects of the first m arketed haemoglobin-based oxygen carrier, Hemoglobin glutamer-200 (bovine) (Hb-200) (Oxyglobin((R))) on splanchnic perfusion and oxygenation in a cani ne model of acute hypovolaemia. Twelve anaesthetized dogs [mean weight 30.8 (S.D. 1.4) kg] were instrumented for recordings of heart rate (HR), mean a rterial pressure (MAP), central venous pressure (CVP), cardiac output and c ranial mesenteric arterial (CMA) and venous blood flows (CMV). Total and pl asma haemoglobin (Hb), oxygen content and saturation. lactate concentration , pH and blood gases were analysed in arterial, mixed venous and mesenteric venous blood samples. Measurements were made before (baseline) and after I h of haemorrhage, after which animals were resuscitated with either shed b lood (controls) or Hb-200 until HR, MAP and CVP returned to prehaemorrhage levels. Recordings were repeated immediately and 3 h after termination of f luid resuscitation, after which organ specimens were obtained for microscop ic examination. Haemorrhage (average 32 ml kg(-1)) reduced MAP to 50 mm Hg, increased HR and systemic vascular resistance (SVR), and was accompanied i n both the systemic and the splanchnic circulation by significant decreases in blood flow, Hb content and oxygen delivery (DO2), and lactic acidosis, in controls, all variables recovered to baseline after isovolaemic resuscit ation with shed blood. In dogs resuscitated with a small volume of Hb-200 ( 10 ml kg(-1)), HR, MAP, CVP and CMA and CMV blood flows returned to baselin e. However, cardiac output, total Hb, oxygen content and systemic and mesen teric DO2 remained depressed while SVR increased further. Mesenteric and sy stemic acid-base status recovered in both groups, and there was no differen ce in microscopic tissue damage between groups. Thus, Hb-200 reconstituted splanchnic perfusion and oxidative metabolism in spite of pronounced system ic vasoconstriction and insufficient restoration of CO and DO2; it may impr ove diffusive oxygen transport in the microvasculature by virtue of haemodi lution and its high efficiency in the uptake and release of oxygen.