Optoelectronic plethysmography: intra-rater and inter-rater reliability in healthy subjects

Optoelectronic plethysmography (OEP) has been used to measure changes in chest wall volume and its compartments. However, literature lacks research on its reliability. The purpose of this study was to evaluate the intra-rater and inter-rater reliability of OEP. Thirty-two healthy subjects were evaluated at rest and during submaximal exercise on a cycle ergometer. The following variables were assessed: chest wall volume (VCW); percentage contribution of the pulmonary rib cage (V(rcp)%), abdominal rib cage (V(rca)%), rib cage (V(rc)%) and abdomen (Vab%); chest wall end-expiratory volume (Vee(cw)); chest wall end-inspiratory volume (Vei(cw)); ratio of inspiratory time to total time of the respiratory cycle (Ti/T(tot)); respiratory rate (f) and mean inspiratory flow (V(cw)/Ti). Intraclass correlation coefficient (ICC) and coefficient of variation of Method Error (CV(ME)) were used to evaluate reliability. Results showed ICC values higher than 0.75 and CV(ME) values less than 10% for most variables at rest and during exercise indicating that OEP is a reliable instrument to assess chest wall volumes at rest and during exercise in healthy subjects.