Abstract
To assess early small airway disease in CF patients with minimal pulmonary involvement, maximal expiratory flow volume (MEFV) curves were obtained while the children were breathing first air and then an 80% helium - 20% oxygen gas mixture. Fifteen CF patients and 24 normal children were studied. Maximal flow rates (Vmax) at 50 and 25% vital capacity (VC) were calculated from the air and helium-mixture MEFV curves and compared to give flow ratios (helium Vmax/air Vmax) at these lung volumes. At 50% VC, the helium/air ratios were similar in CF patients and normal subjects. At 2S% VC, the ratio was significantly lower (p<0.05) in the CF patients. The air and helium MEFV curves from each subject were superimposed and the point where the curves crossed (point of identical flow-PIF) determined and expressed as % VC. For the CF patients, the mean PIF was 18.3% VC and for the controls, 4.9% VC (p<.001). Nine of the 15 CF patients had PIF values greater than 2 S.D. from the normal mean. None of the following tests were abnormal in more than 3 patients: FEV1/FVC, MMEF, RV/TLC and Vmax 25 and 50% TLC. Closing volumes were normal in all patients. Determination of the PIF appears to be a simple, noninvasive, and sensitive test for the detection of early small airway involvement in CF.
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Taussig, L., Bureau, M., Fox, W. et al. VALUE OF AIR AND HELIUM-OXYGEN FLOW-VOLUME CURVES IN DETECTION OF EARLY SMALL AIRWAY DISEASE IN CYSTIC FIBROSIS (CF). Pediatr Res 8, 470 (1974). https://doi.org/10.1203/00006450-197404000-00783
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DOI: https://doi.org/10.1203/00006450-197404000-00783