Effects of Acute Hypocapnia on Postural Standing Balance Measured by Sharpened Romberg Testing (SRT) in Healthy Subjects.

Introduction: The sharpened Romberg test (SRT) is a physical maneuver that has been used to identify ataxia in individuals in resource-limited settings. Previous research has suggested that performance on balance testing may be affected by hypocapnia. In this study, we sought to determine whether acute hyperventilation-induced hypocapnia affects performance on the SRT at 501 meters above sea level.

Methods: We recruited 22 healthy subjects. Each subject performed a baseline SRT. Subjects were then asked to hyperventilate to the point of hypocapnia, confirmed by measurement with a capnometer. Subjects were then asked to re-perform SRT. The primary endpoint was time to loss of balance, measured as time-to-stepout.

Results: Time-to-stepout (TTS) on SRT at baseline had a mean ± standard deviation of 101 ± 117 s. In the hypocapnic condition, TTS was reduced to 48 ± 68 s. TTS normalized to 121 ± 132 s after recovery to normal capnic levels. Time-to-stepout was found to be significantly shorter in the hypocapnic measurement compared to the baseline measurement (P = .0128). Statistical analysis was conducted using one-tailed, paired sample T-tests using a P-value of < .05.

Conclusions: Our study found a statistically and clinically significant reduction in performance on a balance test (SRT) when exposed to acute hyperventilation-induced hypocapnia compared to a eucapnic control. Our results suggest that acute hypocapnia may contribute to neurological dysfunction independently of hypobaric hypoxia.