From the Guidelines
The best explanation for adequate oxygen delivery to tissues at rest in an acclimatized person at high altitudes is that hemoglobin concentration increases. At high altitudes, where atmospheric oxygen pressure is lower, the body compensates through several physiological adaptations, as described in the study by 1. The most significant of these is an increase in hemoglobin concentration, which occurs through increased erythropoietin production that stimulates red blood cell formation. This adaptation allows the blood to carry more oxygen molecules despite the lower partial pressure of oxygen in the arterial blood. Some key points to consider include:
- Increased ventilation and cardiac output also contribute to adequate tissue oxygenation
- The increase in hemoglobin concentration is the primary mechanism that enables adequate tissue oxygenation in acclimatized individuals at high altitudes
- Arterial PO2 remains lower than at sea level, but the increased hemoglobin concentration effectively compensates for this deficit, ensuring that sufficient oxygen reaches the tissues during rest, as supported by the findings of 1. The physiological responses that help to maintain adequate tissue O2 delivery and supply at high altitudes, through a process called ‘acclimatization’, are crucial in this context, and are discussed in detail by 1.