Cross-sectional study of loop gain abnormalities in childhood obstructive sleep apnea syndrome.

STUDY OBJECTIVES

We aimed to assess ventilatory control in typically developing children with and without obstructive sleep apnea (OSA).

METHODS

Otherwise healthy children referred for suspicion of OSA were recruited. In addition to polysomnography, we analyzed loop, controller and plant gains (ie, LG, CG, and PG), which reflect the stability of control, chemoreceptor sensitivity and the pulmonary control of blood gases in response to changes in ventilation, respectively, from tidal breathing recordings during wakefulness. Two bivariate (ventilation, end-tidal CO: one unconstrained and one constrained) and one trivariate (plus end-tidal oxygen) unconstrained model were used to assess model consistency and oxygen chemosensitivity.

RESULTS

In sum, 54 children (median age 11.6 years) were included. Children with OSA (n = 19, [obstructive apnea-hypopnea index] OAHI ≥2.h) had a higher plant gain compared with those without OSA (n = 35), and it was positively correlated with apnea hypopnea index (AHI) (r = 0.10, p < 0.020). The two models showed consistent results. The bivariate constrained model showed that children with OAHI ≥5.h showed an increased steady-state plant gain compared with children with OAHI <5.h. The trivariate model did not show evidence of any abnormality of oxygen chemosensitivity.

CONCLUSION

Plant gain may contribute to OSA pathophysiology in children, and therapies directed at its reduction should be tested.