Clinical physiology (Oxford, England)
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In bronchial asthma, measurement of absolute lung volumes may reveal lung dysfunction more readily than forced expiratory spirometry. Sixty-one children (aged 4-16 years) with mild to moderate bronchial asthma and 35 children (aged 7-16 years) with other symptoms of the lower airways (OSLA) were studied, and the plethysmographic results were compared with data obtained from 36 healthy volunteers aged 6-16 years. In the first test session, repeatability of forced expiratory volume in one second (FEV1), forced vital capacity (FVC), residual volume (RV), functional residual capacity (FRC) and total lung capacity (TLC) were good. ⋯ An increase of > or = 5% in FEV1 had a positive predictive value of 44% and a negative predictive value of 68% for the clinical diagnosis of bronchial asthma; for a decrease of > or = 24% in RV, the figures were 86% and 71% respectively. The support of baseline absolute lung volumes on clinical decision-making is not necessarily great. Bronchodilator response, particularly in RV, is more pertinent and may enhance the detection of reversible lung dysfunction.