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Predicting arterial oxygen tension from maximum expiratory flow volume curves in cystic fibrosis
Author(s) -
Stecenko Arlene A.,
Postotnik Linda,
Thomas Ronald G.
Publication year - 1989
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.1950060108
Subject(s) - medicine , hypoxemia , vital capacity , cardiology , logistic regression , cystic fibrosis , univariate analysis , anesthesia , lung , lung function , multivariate analysis , diffusing capacity
Measurements of arterial oxygen tension (Pa O 2 ) while breathing room air, and maximum expiratory flow volume curves were performed in 34 patients with cystic fibrosis (age range 7–27 years, 24 males and 10 females). Logistic regression was performed using forced vital capacity (FVC), forced expiratory volume in 1 second (FEV 1 ), peak expiratory flow rate (PEFR), and forced expiratory flow at 75% of expired vital capacity (FEF 75 ) to model an equation for predicting when Pa O 2 would be less than 55 mmHg (severe hypoxemia). Equations were modelled using one, two, three, or all four of the variables. For the univariate logistic regression, each of the four variables was a significant ( P < 0.001) predictor for severe hypoxemia. FVC was the best predictor with an R 2 = 0.56, sensitivity of 100% (false negative rate = 0%), and a specificity of 88.5% (false positive rate = 27%). The model predicted that patients with an FVC < 35% of the predicted normal were at risk of having Pa O 2 ≤ 55 mmHg. Adding FEV 1 , FEF 75 , or PEFR in various combinations to FVC made the model equation more complicated but did not add significantly to the ability to predict severe hypoxemia.