Loop gain in severely obese women with obstructive sleep apnoea

•The concept of loop gain describes stability and variability of respiratory control.•An enhanced CO2 plant gain is evidenced in obese women with obstructive sleep apnoea.•A reduced central CO2 controller gain is evidenced in obese women with OSA.

Our objective was to assess whether obstructive sleep apnoea (OSA) patients were characterised by a reduced central CO2 controller gain (CG) and an enhanced plant gain (PG). We matched three groups of women (n = 10 per group) enrolled in a previous study (Essalhi et al., J. Asthma. 50: 565–572, 2013): obese women with a respiratory disturbance index (RDI) ≥ 15/h and with a RDI < 15, and lean women without OSA (RDI < 5). Tidal ventilation recordings during wakefulness with end-tidal PCO2 monitoring allowed the assessment of loop gain (LG) and its components (PG and CG).LG were similar for the three groups (p = 0.844) while both PG and CG depicted significant differences (p = 0.046 and p = 0.011, respectively). Obese women with OSA were characterised by an increased PG and a reduced CG as compared to obese women without OSA. A negative relationship between CG and RDI (rho = −0.46, p = 0.008) was evidenced.In conclusion, OSA in women is associated with a reduced central CO2 controller gain and an enhanced plant gain.