Lung aeration during sleep
2007 (English)In: Chest, ISSN 0012-3692, E-ISSN 1931-3543, Vol. 131, no 1, 122-129 p.Article in journal (Refereed) Published
Background: During sleep, ventilation and functional residual capacity (FRC) decrease slightly. This study addresses regional lung aeration during wakefulness and sleep. Methods: Ten healthy subjects underwent spirometry awake and with polysomnography, including pulse oximetry, and also CT when awake and during sleep. Lung aeration in different lung regions was analyzed. Another three subjects were studied awake to develop a protocol for dynamic CT scanning during breathing. Results: Aeration in the dorsal, dependent lung region decreased from a mean of 1.14 ± 0.34 mL (± SD) of gas per gram of lung tissue during wakefulness to 1.04 ± 0.29 mL/g during non-rapid eye movement (NREM) sleep (- 9%) [p = 0.034]. In contrast, aeration increased in the most ventral, nondependent lung region, from 3.52 ± 0.77 to 3.73 ± 0.83 mL/g (+ 6%) [p = 0.007]. In one subject studied during rapid eye movement (REM) sleep, aerationdecreased from 0.84 to 0.65 mL/g (- 23%). The fall in dorsal lung aeration during sleepcorrelated to awake FRC (R2 = 0.60; p = 0.008). Airway closure, measured awake, occurred near and sometimes above the FRC level. Ventilation tended to be larger in dependent, dorsal lung regions, both awake and during sleep (upper region vs lower region, 3.8% vs 4.9% awake, p = 0.16, and 4.5% vs 5.5% asleep, p = 0.09, respectively). Conclusions: Aeration is reduced in dependent lung regions and increased in ventral regions during NREM and REM sleep. Ventilation was more uniformly distributed between upper and lower lung regions than has previously been reported in awake, upright subjects. Reduced respiratory muscle tone and airway closure are likely causative factors.
Place, publisher, year, edition, pages
2007. Vol. 131, no 1, 122-129 p.
Airway closure, Anesthesia, CT, Lung aeration, Lung volume, Sleep, Ventilation
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:kth:diva-86302DOI: 10.1378/chest.06-0359ISI: 000243548100020OAI: oai:DiVA.org:kth-86302DiVA: diva2:500603
QC 201202282012-02-132012-02-132012-02-28Bibliographically approved