Tourniquet Use and Hemoglobin Oxygen Affinity: Understanding the Impact

Prolonged tourniquet application causes tissue hypoxia, leading to oxygen unloading from hemoglobin. This decreases the oxygen-hemoglobin affinity (lower P50/k value), reducing the blood's oxygen-carrying capacity. The effect is reversible upon release but underscores the need for strict tourniquet time limits (typically ≤2 hours) to prevent ischemic injury.