Variability of the raised volume rapid thoracic compression technique in infants with recurrent wheezing.

Measuring forced expiratory flows from raised lung volume in infants represents a significant advance in the assessment of pulmonary function early in life. However, variability in the main parameters obtained with raised volume rapid thoracic compression (RVRTC), FVC, FEV(0.5), FEF(50), FEF(75), and FEF(25-75), has not been completely evaluated. This study was performed to determine the intra-subject variability of spirometric-like parameters in infants with recurrent wheezing obtained with RVRTC. One hundred and two infants with recurrent wheezing (mean age 62 +/- 22 weeks) who were asymptomatic at the moment of measuring lung function participated in this study. For the variability analysis, three to five technically acceptable curves at flow-limitation jacket pressure were employed. The mean coefficient of variation (95 % CI) of spirometric parameters was as follows: FVC = 2.9 % (2.6-3.2); FEV(0.5) = 2.2 % (1.9-2.5); FEF(50) = 3.7 % (3.3-4.1); FEF(75) = 5.9 % (5.2-6.6) and FEF25-75 = 3.3 % (2.9-3.7). This study demonstrates the high reproducibility of the spirometric parameters measured with the technique of raised lung volume in infants.