LAUSR

Before pulmonary rehabilitation COPD-patients undergo extensive assessment. One of the goals of this assessment is to determine whether COPD-patients demonstrate dynamic hyperinflation (DH). Both constant-work-rate test (CWRT) and metronome paced tachypnea (MPT) were used to diagnose DH. This prospective cohort study was intended to assess the diagnostic value of MPT and to determine whether MPT alone is sufficient to diagnose DH. By doing so, the volume measurements, necessary to determine DH, do not to have be carried out during CWRT, which is currently the golden standard. From January to October 2015, 75 patients with COPD were included (FEV1 45±17; FRC 151±36; in% predicted) and performed CWRT and MPT. The used cut-off value to diagnose DH after CWRT was a decrease in inspiratory capacity (IC) of 20%. To determine the cut-off value to diagnose DH after MPT, a receiver operating characteristic (ROC) analysis was performed. A contingency table was used to separate patients that demonstrate DH at CWRT and/or MPT from those who did not. Thereafter, sensitivity, specificity, PPV and NPV of MPT were determined. Results: At a 20% decrease of IC as cut-off value for DH during CWRT the optimum cut-off value for MPT was 19,2%(AUC 0,691; 95%CI 62-84%). If the cut-off value of 19,2% was used for MPT, it had a sensitivity of 74% (95%CI 62-84%) and a specificity of 54% (95%CI 32-72%). The PPV and NPV were 70% and 52% respectively. Conclusion: MTP seems to be an accurate way to diagnose DH. Therefore, using only MPT to diagnose DH may be considered. Additional clinical symptoms of DH could support this diagnosis in the laboratory. Further study into specification of the exclusion criteria seems appropriate