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Inherent variability of pulmonary function tests in infants with bronchiolitis
J Mallol1, M E Hibbert, C F Robertson
1Department of Thoracic Medicine, Royal Children's Hospital, Parkville, Victoria, Australia.
Pediatric Pulmonology
|January 1, 1988
Summary
Infant pulmonary function tests show high variability, especially when infants are repositioned. This increased variability can impact studies on inhaled medications, necessitating individual test assessments before therapeutic intervention studies.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Clinical Trial Methodology
Background:
- New infant pulmonary function assessment methods have emerged, yet their use in evaluating inhaled medications remains controversial.
- Existing variability data for infant pulmonary function tests may not apply to drug efficacy studies due to time intervals and repositioning.
Purpose of the Study:
- To investigate the variability of infant pulmonary function tests when infants are repositioned between measurements.
- To assess the impact of repositioning on measurements of thoracic gas volume, passive respiratory mechanics, and forced expiration.
Main Methods:
- Measurements of thoracic gas volume (TGV), passive respiratory mechanics, and forced expiration were performed.
- Infants were either removed from the plethysmograph or repositioned within it between measurement sets.
- Between-test coefficients of variation were calculated for various pulmonary function parameters.
Main Results:
- Variability of TGV, respiratory system resistance, respiratory system compliance, and maximal flow measurements approximately doubled with infant repositioning.
- Between-test coefficients of variation ranged from 4.8% to 36.1% across different pulmonary function tests.
- Significant variability was observed in commonly used infant pulmonary function tests in infants with acute wheezing.
Conclusions:
- Commonly employed infant pulmonary function tests exhibit wide variability in infants with acute wheezing illnesses.
- Establishing individual test variability under study conditions is crucial before investigating therapeutic interventions in these infants.
- Failure to account for individual variability may lead to erroneous conclusions in drug efficacy studies.