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Updated: Jul 4, 2026

A Model to Simulate Clinically Relevant Hypoxia in Humans
Published on: December 22, 2016
Effect of oxygen in obstructive sleep apnea: role of loop gain
Andrew Wellman1, Atul Malhotra, Amy S Jordan
1Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. awellman@rics.bwh.harvard.edu
Abstract:
We compared the effect of oxygen on the apnea-hypopnea index (AHI) in six obstructive sleep apnea patients with a relatively high loop gain (LG) and six with a low LG. LG is a measure of ventilatory control stability. In the high LG group (unstable ventilatory control system), oxygen reduced the LG from 0.69+/-0.18 to 0.34+/-0.04 (p<0.001) and lowered the AHI by 53+/-33% (p=0.04 compared to the percent reduction in the low LG group). In the low LG group (stable ventilatory control system), oxygen had no effect on LG (0.24+/-0.04 on room air, 0.29+/-0.07 on oxygen, p=0.73) and very little effect on AHI (8+/-27% reduction with oxygen). These data suggest that ventilatory instability is an important mechanism causing obstructive sleep apnea in some patients (those with a relatively high LG), since lowering LG with oxygen in these patients significantly reduces AHI.
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