Document Detail

Comparison of maximal midexpiratory flow rate and forced expiratory flow at 50% of vital capacity in children.
MedLine Citation:
PMID:  12628870     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The mid-portion of the maximal expiratory flow-volume (MEFV) curve is often described by values of the mean forced expired flow as lung volume decreases from 75% to 25% of vital capacity (ie, forced expiratory flow, midexpiratory phase [FEF(25-75)]). It is common practice to report also forced expired flow at 50% of vital capacity (FEF(50)). STUDY OBJECTIVE: To investigate whether FEF(50) and FEF(25-75) are highly correlated or whether the difference between them reflects a degree of airways obstruction. Also, we wanted to investigate the correlation between the two in cases of irregularly shaped MEFV curves (ie, "saw-toothing"). DESIGN: Analysis of the correlation between FEF(50) and FEF(25-75) in a single determination. We assessed the relationship between the FEF(50)/FEF(25-75) ratio and the degree of airways obstruction, as reflected by other traditional parameters such as FEV(1), FEV(1)/FVC ratio, and specific airway conductance (SGaw). PATIENTS: There were 1,350 forced expiratory maneuvers performed by children with a broad range of pulmonary abnormalities. RESULTS: FEF(50) correlated with FEF(25-75) as follows: FEF(50) (L/s) = 0.041 + 1.136*FEF(25-75)(L/s); r(2) = 0.956; standard error of the estimate = 0.013; p < 0.0001. The FEF(50)/FEF(25-75) ratio remained stable and did not correlate with FEV(1) (r = 0.12), FEV(1)/FVC ratio (r = 0.11), or SGaw (r = 0.02; difference not significant). The correlation between FEF(25-75) and FEF(50) was similar for both the smooth curve (r = 0.97) and the irregular curve (r = 0.96). CONCLUSIONS: Although not identical, FEF(25-75) and FEF(50) are highly correlated, and the ratio of the two is fairly constant. Therefore, the practice of reporting both of them is unnecessary. We suggest that it is reasonable to prefer FEF(50).
Ephraim Bar-Yishay; Israel Amirav; Shmuel Goldberg
Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Chest     Volume:  123     ISSN:  0012-3692     ISO Abbreviation:  Chest     Publication Date:  2003 Mar 
Date Detail:
Created Date:  2003-03-11     Completed Date:  2003-04-02     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0231335     Medline TA:  Chest     Country:  United States    
Other Details:
Languages:  eng     Pagination:  731-5     Citation Subset:  AIM; IM    
Institute of Pulmonology, Hadassah University Hospital, Jerusalem, Israel. EPHRAIMB@CC.HUJI.AC.IL
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MeSH Terms
Forced Expiratory Flow Rates / physiology*
Linear Models
Lung Diseases / diagnosis
Maximal Expiratory Flow Rate / physiology*
Models, Biological
Spirometry / methods*
Vital Capacity
Comment In:
Chest. 2003 Mar;123(3):667-8   [PMID:  12628856 ]

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