To assess the relationship between central control of upper airway and respiratory muscle, simultaneously recorded diaphragmatic electromyogram (EMGdi) and genioglossal EMG (EMG ge) responses to CO2 rebreathing were compared in five supine volunteers. Both EMGs were quantitated in terms of inspiratory peak moving time-average activity. In all subjects both EMGdi and EMGge increased linearly with increasing alveolar CO2 pressure (r = 0.93 +/- 0.04 and 0.87 +/- 0.07, respectively), resulting in a significantly linear EMGge vs. EMGdi relationship (r = 0.91 +/- 0.04). CO2 response slopes of both EMGs were similar and linearly related (r = 0.96, P less than 0.001) such that subjects with low EMGdi response also had a low EMGge response and vice versa. Although the onset of EMGge activity preceded that of EMGdi, and the pattern of both EMGs were different, inspiration duration of both EMGs were similar. These data indicate that in humans both diaphragm and genioglossus muscle share similar control mechanisms and suggest that upper airway function is intimately related to the regulation of breathing.
To test the hypothesis that occlusive apneas result from sleep-induced periodic breathing in association with some degree of upper airway compromise, periodic breathing was induced during non-rapid-eye-movement (NREM) sleep by administering hypoxic gas mixtures with and without applied external inspiratory resistance (9 cmH2O X l-1 X s) in five normal male volunteers. In addition to standard polysomnography for sleep staging and respiratory pattern monitoring, esophageal pressure, tidal volume (VT), and airflow were measured via an esophageal catheter and pneumotachograph, respectively, with the latter attached to a tight-fitting face mask, allowing calculation of total pulmonary system resistance (Rp). During stage I/II NREM sleep minimal period breathing was evident in two of the subjects; however, in four subjects during hypoxia and/or relief from hypoxia, with and without added resistance, pronounced periodic breathing developed with waxing and waning of VT, sometimes with apneic phases. Resistive loading without hypoxia did not cause periodicity. At the nadir of periodic changes in VT, Rp was usually at its highest and there was a significant linear relationship between Rp and 1/VT, indicating the development of obstructive hypopneas. In one subject without added resistance and in the same subject and in another during resistive loading, upper airway obstruction at the nadir of the periodic fluctuations in VT was observed. We conclude that periodic breathing resulting in periodic diminution of upper airway muscle activity is associated with increased upper airway resistance that predisposes upper airways to collapse.
SUMMARYThe goal of this study was to characterize sleep and respiratory parameters in children with sleep-disordered breathing (SDB) as compared to children without SDB. Data are from 198 children and adolescents referred for sleep center evaluation, 128 of whom were diagnosed with SDB. In children with SDB, obesity (> 95% wgt for age) was more common than being severely underweight (< 5% wgt for age), but only the older children with SDB were heavier than age-matched normal sleepers. Children with SDB had increased EEG arousals; sleep architecture was not otherwise significantly different from the non-SDB group. African-American children with SDB had significantly greater oxygen desaturation with obstructive events compared to Caucasian and Latino children. It appears that the role of obesity as a risk factor for obstructive sleep apnea (OSA) increases in children above the age of 8-years. Additionally, African-American children with SDB may be at increased risk for hypoxemia and cardiovascular consequences of SDB.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.