Effect of oxygen in obstructive sleep apnea: role of loop gain.
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.
Wellman
Andrew
A
Division of Sleep Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA. awellman@rics.bwh.harvard.edu
Malhotra
Atul
A
Jordan
Amy S
AS
Stevenson
Karen E
KE
Gautam
Shiva
S
White
David P
DP
D000328:Adult; D000368:Aged; D000403:Airway Resistance / Q000502:physiology; D000465:Algorithms; D016022:Case-Control Studies; D002639:Cheyne-Stokes Respiration / Q000150:complications / Q000628:therapy; D005246:Feedback / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010100:Oxygen / Q000008:administration & dosage*; D017286:Polysomnography; D011175:Positive-Pressure Respiration / Q000379:methods*; D012123:Pulmonary Ventilation / Q000502:physiology*; D012016:Reference Values; D015656:Respiratory Mechanics / Q000502:physiology*; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome
D010100:Oxygen