Comparison of thoracoabdominal synchrony using two methods in healthy subjects, chronic obstructive and interstitial lung disease

Thoracoabdominal asynchrony (TAA) is defined as the no coincident motion of ribcage (RC) and abdomen (AB). It is estimated by respiratory inductive plethysmography (RIP), and recently with optoelectronic plethysmography (OEP). The agreement of TAA measurements with both remains unknown. OBJECTIVE: to compare TAA estimated by RIP and OEP. METHODS: 9 healthy subjects; 9 interstitial lung disease (ILD) (FVC 1 57.2±10.8%pred) and 9 COPD patients (FEV 1 38±12.6%pred) performed 2 cycle ergometer tests with 30 minutes between them in a random order. TAA was evaluated in 3 conditions: at rest, 50% (L 50 ) and 75% (L 75 ) of maximal workload obtained in a previous day. TAA was calculated between RC and AB using phase angle (PA) obtained with Lissajous approach. It was analyzed a mean cycle of 5 last respirations of every phase. RESULTS: TAA values were very similar in both approaches not only at rest but also in exercises and were within the limits of agreement in Bland-Altman analysis. CONCLUSION: TAA obtained by OEP or RIP results in similar values and has a satisfactory agreement at rest and even for different exercise intensities in these groups.