Suggested predictive indices for high altitude pulmonary oedema

Area of Science:

• Physiology
• Altitude Medicine
• Cardiopulmonary Responses

Background:

• High altitude exposure poses risks, including high altitude pulmonary edema (HAPE).
• Individual susceptibility to HAPE varies, necessitating screening methods.
• Understanding physiological responses to hypoxia is crucial for acclimatization and prevention.

Purpose of the Study:

• To evaluate chemoreceptor and pulmonary vascular responses to hypoxia in HAPE-susceptible (HAPE-S) soldiers versus healthy controls.
• To determine if hypoxic ventilatory response (HVR) and pulmonary artery pressure (PAP) changes can serve as screening tests for high altitude (HA) maladies.
• To compare physiological responses to simulated hypoxia between HAPE-S and non-HAPE-susceptible groups.

Main Methods:

• Two groups of soldiers were studied: Group A (no HA maladies) and Group B (HAPE-susceptible).
• Hypoxic ventilatory response (HVR) was measured to assess chemoreceptor function.
• Pulmonary artery pressure (PAP) was monitored during exposure to hypoxic gas mixtures (HGM) to evaluate pulmonary vascular responses.

Main Results:

• HAPE-S subjects (Group B) demonstrated significantly reduced HVR compared to Group A (3.51 L vs. 11.39 L increase in ventilation).
• Group B exhibited significantly elevated systolic, diastolic, and mean PAP under HGM breathing compared to Group A.
• These findings indicate distinct physiological responses to hypoxia in HAPE-susceptible individuals.

Conclusions:

• Reduced HVR and elevated PAP under hypoxia are characteristic of HAPE-susceptible individuals.
• HVR and PAP measurements show potential as screening tools for identifying soldiers and sojourners at risk for HA maladies.
• Further validation of these tests could aid in preventing HAPE and other high-altitude illnesses.