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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1997-3-11
pubmed:abstractText
In normal subjects 2 min of maximal voluntary hyperventilation results in failure of tension generation and low-frequency fatigue of the diaphragm. Patients with severe chronic obstructive pulmonary disease (COPD) do not develop diaphragm fatigue during exhaustive treadmill exercise despite excessive inspiratory muscle loading and we hypothesized that they might be relatively resistant to the development of diaphragm fatigue during maximal ventilation. In six patients with severe COPD (mean FEV1 0.671) we therefore loaded the diaphragm using 2 min of maximal isocapnic ventilation (MIV). Initial mean ventilation was 28.6 L/min and diaphragm pressure-time product (PTPdi) 602 cm H2O x s/min; these values were sustained throughout MIV without significant decline. Mean twitch transdiaphragmatic pressure (Tw Pdi) was 19.7 cm H2O 25 min after a control run and 20.5 cm H2O at the same time after MIV [corrected]. Compared with normal subjects previously studied in our laboratory (Hamnegard, C.-H., et al. Eur. Respir. J. 1996;9:241-247) the reduction in PTPdi was disproportionately greater than the reduction in Tw Pdi. We conclude that, unlike normal subjects, 2 min of MIV causes neither failure of diaphragm performance nor low-frequency diaphragm fatigue in patients with severe COPD. It is likely that the diaphragm makes a relatively limited contribution to the generation of maximal levels of ventilation in severe COPD.
pubmed:commentsCorrections
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
1073-449X
pubmed:author
pubmed:issnType
Print
pubmed:volume
155
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
642-8
pubmed:dateRevised
2004-11-17
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Diaphragm performance during maximal voluntary ventilation in chronic obstructive pulmonary disease.
pubmed:affiliation
Respiratory Muscle Laboratory, Kings College Hospital, London, United Kingdom.
pubmed:publicationType
Journal Article