The influence of oxyhemoglobin affinity on tissue oxygen consumption

In an intact animal or patient, any shift in oxyhemoglobin affinity is inevitably associated with concurrent fluctuation in numerous other determinants of oxygen delivery. For this reason, the influence of hemoglobin affinity for oxygen on tissue oxygen consumption has been incompletely evaluated. The purpose of this study was to investigate the influence of oxyhemoglobin affinity as the sole variable of oxygen delivery in an isolated perfused canine hindlimb. A membrane lung system which allowed precise control of blood flow, temperature, arterial oxygen content and arterial pH was established. Twelve isolated canine hindlimbs were alternatively perfused with autologous stored (left-shifted) and fresh (right-shifted) blood in paralled perfusion systems. The 2,3-DPG concentrations, P50 and oxygen consumptions were significantly different in the two paralled perfusion systems. A decreased hemoglobin affinity for oxygen appeared to permit increased oxygen off-loading at the tissue level.