Forced expiratory maneuvers in very young children - Assessment of flow limitation

The application of negative expiratory pressure (NEP) to the airway opening during forced expiratory maneuvers has recently been described as a noninv asive method to assess whether flow limitation is achieved in adults. This methodology has great potential for extending the measurement of forced exp iratory maneuvers to young children who may not produce maximal efforts as reproducibly as adults. We used NEP to assess flow limitation in 10 childre n between 3 and 5 yr of age. NEP was well tolerated by all subjects. With t he application of NEP, there was not a step increase in flow, a finding con sistent with flow limitation for the subjects. In addition to visual inspec tion, we proposed a method to quantify the change in flow during a short NE P. The flow-volume curves obtained with and without NEP were visually the s ame, other than the flow transients produced by NEP. The calculated values of FVC and FEF25-75, were not significantly different when measured from fl ow-volume curves with and without NEP. There was a statistically significan t increase in FEV1 with NEP; however, the group mean increase in FEV1 was l ess than 2%. We conclude that NEP may be a useful technique to determine wh ether flow limitation has been achieved in young children performing forced expiratory maneuvers.