Document Detail

Effect of hypercapnia on total pulmonary resistance during wakefulness and during NREM sleep.
MedLine Citation:
PMID:  1859068     Owner:  NLM     Status:  MEDLINE    
We investigated the effect of different levels of hypercapnia on total pulmonary resistance (RL) in 13 subjects ranging from nonsnorers with low RL to snorers with high RL and dynamic narrowing of the upper airway during inspiration. Added CO2 was adjusted to achieve a steady-state increase in PETCO2 of +2, +4, or +6 mm Hg. RL was measured at peak inspiratory flow (RLpf), at maximal resistance within breath (RLmax), and at 10 equally spaced points within inspiration in several trials. During wakefulness, hypercapnia was associated with decreased RLmax. During steady state +6 mm Hg hypercapnia, RLmax decreased by 30% (p less than 0.01). During NREM sleep, low levels of hypercapnia did not affect RL. However, +6 mm Hg hypercapnia was associated with decreased RLmax in six of eight subjects (p = 0.07), especially in subjects with high RLmax during room air breathing. The effects of hypercapnia on RLpf paralleled its effect on RLmax. We concluded that (1) the decrease in RL during awake hypercapnia suggests an increase in upper airway dimensions and stiffness, (2) the absence of increased RL during low level NREM hypercapnia (despite the increase in inspiratory flows and collapsing pressures) also suggests an increase in upper airway dimensions and stiffness, and (3) upper airway dilating muscles appear to be recruited in a coordinated fashion with inspiratory muscles in normal humans during NREM sleep. The implications of these findings in patients with obstructive sleep apnea are not clear at this point.
M S Badr; J B Skatrud; P M Simon; J A Dempsey
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American review of respiratory disease     Volume:  144     ISSN:  0003-0805     ISO Abbreviation:  Am. Rev. Respir. Dis.     Publication Date:  1991 Aug 
Date Detail:
Created Date:  1991-08-29     Completed Date:  1991-08-29     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370523     Medline TA:  Am Rev Respir Dis     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  406-14     Citation Subset:  AIM; IM; S    
Medical Service, William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin.
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MeSH Terms
Airway Resistance / physiology
Hypercapnia / physiopathology*
Pulmonary Gas Exchange / physiology
Respiratory Mechanics / physiology*
Respiratory Muscles / physiology
Sleep / physiology*
Snoring / physiopathology
Wakefulness / physiology*
Grant Support
P01 HL-42242-01/HL/NHLBI NIH HHS

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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