Effect of oxygen in obstructive sleep apnea: role of loop gain.

Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
Respiratory Physiology & Neurobiology (Impact Factor: 1.97). 06/2008; 162(2):144-51. DOI: 10.1016/j.resp.2008.05.019
Source: PubMed

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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Mar 2, 2015