Document Detail


A sigmoidal fit for pressure-volume curves of idiopathic pulmonary fibrosis patients on mechanical ventilation: clinical implications.
MedLine Citation:
PMID:  21876967     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: Respiratory pressure-volume curves fitted to exponential equations have been used to assess disease severity and prognosis in spontaneously breathing patients with idiopathic pulmonary fibrosis. Sigmoidal equations have been used to fit pressure-volume curves for mechanically ventilated patients but not for idiopathic pulmonary fibrosis patients. We compared a sigmoidal model and an exponential model to fit pressure-volume curves from mechanically ventilated patients with idiopathic pulmonary fibrosis.
METHODS: Six idiopathic pulmonary fibrosis patients and five controls underwent inflation pressure-volume curves using the constant-flow technique during general anesthesia prior to open lung biopsy or thymectomy. We identified the lower and upper inflection points and fit the curves with an exponential equation, V = A-B.e-k.P, and a sigmoid equation, V = a+b/(1+e-(P-c)/d).
RESULTS: The mean lower inflection point for idiopathic pulmonary fibrosis patients was significantly higher (10.5 ± 5.7 cm H2O) than that of controls (3.6 ± 2.4 cm H₂O). The sigmoidal equation fit the pressure-volume curves of the fibrotic and control patients well, but the exponential equation fit the data well only when points below 50% of the inspiratory capacity were excluded.
CONCLUSION: The elevated lower inflection point and the sigmoidal shape of the pressure-volume curves suggest that respiratory system compliance is decreased close to end-expiratory lung volume in idiopathic pulmonary fibrosis patients under general anesthesia and mechanical ventilation. The sigmoidal fit was superior to the exponential fit for inflation pressure-volume curves of anesthetized patients with idiopathic pulmonary fibrosis and could be useful for guiding mechanical ventilation during general anesthesia in this condition.
Authors:
Juliana C Ferreira; Fabio E M Benseñor; Marcelo J J Rocha; Joao M Salge; R Scott Harris; Atul Malhotra; Ronaldo A Kairalla; Robert M Kacmarek; Carlos R R Carvalho
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Clinics (São Paulo, Brazil)     Volume:  66     ISSN:  1980-5322     ISO Abbreviation:  Clinics (Sao Paulo)     Publication Date:  2011  
Date Detail:
Created Date:  2011-08-30     Completed Date:  2012-05-14     Revised Date:  2013-11-11    
Medline Journal Info:
Nlm Unique ID:  101244734     Medline TA:  Clinics (Sao Paulo)     Country:  Brazil    
Other Details:
Languages:  eng     Pagination:  1157-63     Citation Subset:  IM    
Affiliation:
Divisão de Pneumologia, Instituto do Coração, Faculdade de Medicina, Universidade de São Paulo, Brazil. julianacarvalhoferreira@gmail.com
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MeSH Terms
Descriptor/Qualifier:
Aged
Case-Control Studies
Female
Humans
Idiopathic Pulmonary Fibrosis / physiopathology*
Lung / physiopathology*
Lung Volume Measurements / methods
Male
Middle Aged
Reproducibility of Results
Respiration, Artificial*
Respiratory Mechanics / physiology*
Grant Support
ID/Acronym/Agency:
K24 HL093218/HL/NHLBI NIH HHS; P01 HL095491/HL/NHLBI NIH HHS; R01 HL085188/HL/NHLBI NIH HHS; R01 HL086717-05/HL/NHLBI NIH HHS; R01 HL090897/HL/NHLBI NIH HHS
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