Objective: To determine the effectiveness of increasing levels of Positive Expiratory Pressure (PEP) during coughing to enhance expiratory flow and improve efficiency of the cough.
Material and method: Forty children aged 8 to 18 years, with repaired tracheo-oespohageal fistula (TOF) and twenty-one age matched controls performed spirometry followed by cough spirometry with PEP of 0, 5, 10, 15 and 20 cmH2O using an adjustable PEP valve. Cough expiratory flow between 75 and 25% of vital capacity (CEF25-75) for each curve was calculated to represent the effectiveness of cough at mid-lung volume, the region of the flow volume curve most vulnerable in tracheomalacia.
Results: In the TOF group, CEF25-75 increased by a mean (95% CI) of 18.8% (4.4, 33.2), 1.7% (-2.6, 26.0) and 0.5% (-13.7, 14.7) at PEP of 5, 10 and 15 cmH2O respectively, but decreased by 2.4% (-13.4, 8.5) at PEP of 20 cmH2O. In the control group the CEF25-75 decreased. The values were -3.1% (-16.7, 10.4), -6.3%(-18.1, 5.6), -22.2% (-33, -11.5) and -19% (-29.3, -8.7) at PEP of 5, 10, 15 and 20cmH2O respectively.
Conclusion: The use of a simple adjustable PEP valve increases CEF25-75 during cough spirometry and may provide a useful adjunct to chest physiotherapy in children with tracheomalacia.