Obstructive sleep apnea (OSA) involves the interplay of several different factors such as an unfavorable upper airway anatomy, deficiencies in pharyngeal muscle responsiveness, a low arousal threshold, and ventilatory control instability. Although the stability of ventilatory control has been extensively studied in adults, little is known about its characteristics in the pediatric population. In this study, we developed a novel experimental setup that allowed us to perturb the respiratory system during natural non-rapid eye movement (NREM) sleep conditions by manipulating the inspiratory pressure, provided by a bilevel pressure ventilator, to induce sighs after upper airway stabilization. Furthermore, we present a modeling framework that utilizes the noninvasively measured ventilatory responses to the induced sighs and spontaneous breathing data to obtain representations of the processes involved in the chemical regulation of respiration and extract their stability characteristics. After validation with simulated data, the modeling technique was applied to data collected experimentally from 11 OSA and 15 non-OSA overweight adolescents. Statistical analysis of the model-derived stability parameters revealed a significantly higher plant gain and lower controller gain in the OSA group (P = 0.046 and P = 0.007, respectively); however, no differences were found in loop gain (LG) and circulatory time delay between the groups. OSA severity and LG, within the 0.03-0.04-Hz frequency band, were significantly negatively associated (r = -0.434, P = 0.026). Contrary to what has been found in adults, our results suggest that in overweight adolescents, OSA is unlikely to be initiated through ventilatory instability resulting from elevated chemical loop gain.

LG and VOMI determined from the ventilatory responses to spontaneous sighs can provide a practical approach to assessing ventilatory control instability in preterm infants. Such simple techniques may help identify infants at particular risk for ventilatory instabilities with concomitant hypoxemia and its associated consequences.

The risk for OSA could be stratified according to controller gain, plant gain, cardiorespiratory coupling, and gestational age. These findings could guide personalized care for children at risk for OSA.

Study Objectives To examine the role of ventilatory control in asthmatic children with obstructive sleep apnea (OSA) and the relationships between measures of ventilatory control, OSA severity, and pulmonary function. Methods Five- to 18-year-old children with persistent asthma and nightly snoring were enrolled in the study. Children had physical examination, pulmonary function test, and polysomnography. Loop and controller gains were derived from 5 min segments which included a sigh during nonrapid eye movement sleep by applying a mathematical model that quantifies ventilatory control from the ensuing responses to the sighs. Plant gain was derived from 5 min segments of spontaneous breathing (i.e. without sighs). Nonparametric statistical tests were used for group comparisons. Cluster analysis was performed using Bayesian profile regression. Results One hundred thirty-four children were included in the study, 77 with and 57 without OSA. Plant gain was higher in children with OSA than in those without OSA (p = 0.002). A negative correlation was observed between plant gain and forced expiratory volume in 1 second (p = 0.048) and the ratio of f forced expiratory volume to forced vital capacity (p = 0.02). Plant gain correlated positively with severity of OSA. Cluster analysis demonstrated that children with more severe OSA and abnormal lung function had higher plant gain and a lower controller gain compared with the rest of the population. Conclusions Children with OSA and persistent asthma with abnormal lung function have phenotypic characteristics which consist of diminished capacity of the lungs to maintain blood gas homeostasis reflected by an increase in plant gain and decreased chemoreceptor sensitivity.

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