Mechanics of the respiratory system and breathing pattern during sleep in normal humans

Abstract

The purposes of this investigation were to describe the changes in 1) dynamic compliance of the lungs, 2) airflow resistance, and 3) breathing pattern that occur during sleep in normal adult humans. Six subjects wore a tightly fitting face mask. Flow and volume were obtained from a pneumotachograph attached to the face mask. Transpulmonary pressure was calculated as the difference between esophageal pressure obtained with a balloon and mask pressure. At least 20 consecutive breaths were analyzed for dynamic compliance, airflow resistance, and breathing pattern during wakefulness, non-rapid-eye-movement stage 2 and rapid-eye-movement (REM) sleep. Dynamic compliance did not change significantly. Airflow resistance increased during sleep; resistance was 3.93 +/- 0.56 cmH2O X 1–1 X s during wakefulness, 7.96 +/- 0.95 in stage 2 sleep, and 8.66 +/- 1.43 in REM sleep (P less than 0.02). By placing a catheter in the retroepiglottic space and thus dividing the airway into upper and lower zones, we found the increase in resistance occurred almost entirely above the larynx. Decreases in tidal volume, minute ventilation, and mean inspiratory flow observed during sleep were not statistically significant.

Obstructive Sleep Apnea in Children: Implications for the Developing Central Nervous System

“…Transition to the sleep state will normally result in elevations of upper airway resistance (22,23), primarily linked to reductions in airway diameter resulting from reduced tone of the pharyngeal dilator and constrictor muscles (24)(25)(26). In children, the primary abnormality associated with increased odds of OSA consists in the presence of adenotonsillar hypertrophy.…”

Supplemental Oxygen Needs During Sleep. Who Benefits?

“…18 This finding is important, given the normal narrowing of the upper airway that occurs during sleep, even without OSA. 19 During wakefulness, pharyngeal muscle activity is maintained by reflex-driven pharyngeal dilator muscle activity. At sleep onset there is reduced reflex muscle activation and wakefulness-modulated excitatory output to the upper airway musculature.…”

Sono e doenças pulmonares crônicas: pneumopatias intersticiais difusas, asma brônquica e DPOC

“…Vários são os fatores responsáveis pela queda da ventilação durante o sono em indivíduos saudáveis: redução da taxa metabólica basal, aumento da resistência da via aérea superior, perda do estímulo da vigília para respirar e fatores relacionados ao sono REM: diminuição do estímulo central muscular respiratório e hipotonia da musculatura acessória e intercostal da respiração. (1) Essas alterações fisiológicas que ocorrem normalmente durante o sono não promovem efeitos deletérios em indivíduos saudáveis. Entretanto, em portadores de doenças pulmonares, especialmente em portadores de DPOC, podem ocorrer acentuada hipoxemia e hipercapnia.…”