Using Echocardiography to Study the Effects of Hypoxia and Altitude on Heart Function

Physiological assessment of military pilots and aircrew is performed annually. This includes a simulation of a flight at maximum altitude (25,000 ft/7620 m) with acute hypoxia, where they can recognize their symptoms. By detecting the symptoms of hypoxia, they will take corrective actions to avoid hypoxia-induced impairment. However, there is little evidence of what happens in the heart under these conditions. Cardiac function can be evaluated noninvasively with transthoracic echocardiography. The objective was to evaluate the effect of hypoxia and altitude during this simulation on systolic and diastolic cardiac function, pulmonary artery systolic pressure, and cardiac output with transthoracic echocardiography.

A total of 72 volunteers (33.90 ± 8.49 yr, 73.6% male) were studied. A baseline transthoracic echocardiography assessment was performed, and systolic and diastolic function were assessed in both left and right ventricles. Cardiac output and pulmonary artery systolic pressure were estimated. Measurements were repeated at 25,000 ft, with and without oxygen, when saturation was below 80%.

A significant decrease was observed under hypoxic conditions when evaluating both right ventricular (RV) systole (RV 12.25 ± 3.1 to 8.9 ± 2.3 cm · s-1) and diastole (RV 6.8 ± 3.5 to 4.8 ± 2.8 cm · s-1 and RV 8.5 ± 5.2 to 5.71 ± 4.1 cm · s-1). However, cardiac output remained stable (7.87 ± 0.58 to 7.68 ± 0.49 L · m-2).

Echocardiography is a useful tool for evaluating left and right cardiac ventricular function. The right ventricle, both in its systolic and diastolic function, was the most affected during a simulated hypobaric and hypoxic flight. Cabrera Schulmeyer MC, Patiño-García D, Alvear M, Aravena D, Montiglio C. Using echocardiography to study the effects of hypoxia and altitude on heart function. Aerosp Med Hum Perform. 2025; 96(11):964-968.