The Effects of the Prone Position on the Physiological Function in Healthy Students

The rapid improvement in blood oxygenation has been observed in patients with acute respiratory failure placed in a prone position. The gravitational effect relieves upper airway narrowing in the prone position, resulting in an improvement in sleep quality. This study examined the effect of the prone position on autonomic nerve activity and car- diovascular function. Seven healthy adults (mean age 25.2 ± 10.6 years) enrolled in this study. The heart rate variability as a marker of autonomic activity, lactate value as a maker of fatigue, vascular function (brachial-ankle pulse wave velocity; baPWV), and blood pressure in the supine and prone position were evaluated. The heart rate variability was calculated us- ing an electrocardiogram to measure the RR interval. The high-frequency (HF) and low-frequency /high-frequency (LF/HF) were calculated on baseline, after 30-min in the supine and prone position. The ratio of baseline HF to that after 30-min significantly increased in the prone position than the supine position. The ratio of baseline LF/HF to that after 30- min in the prone position significantly decreased compared to the supine position. Meanwhile, the ratio of the baseline LF to that after 30-min did not show any significant difference in the prone position in comparison to the supine position. There were no significant differences on lactate value, baPWV and blood pressure change. The prone position might therefore have a beneficial effect on the autonomic function.