<p>Relationships Between Forced Oscillatory Impedance and 6-minute Walk Distance After Pulmonary Rehabilitation in COPD</p>

Abstract

Rationale: Pulmonary rehabilitation for chronic obstructive pulmonary disease (COPD) reduces dyspnoea and improves exercise capacity and quality of life. The improvement in exercise capacity is variable and unpredictable, however. Respiratory system impedance obtained by forced oscillation technique (FOT) as a measure of ventilatory impairment in COPD may relate to improvement in exercise capacity with pulmonary rehabilitation. We aimed to determine if baseline FOT parameters relate to changes in exercise capacity following pulmonary rehabilitation. Methods: At the start of rehabilitation, 15 COPD subjects (mean(SD) 75.2(6.1) years, FEV1 z-score −2.61(0.84)) had measurements by FOT, spirometry, plethysmographic lung volumes and 6-minute walk distance (6MWD). Respiratory system resistance (Rrs) and reactance (Xrs) parameters as the mean over all breaths (R mean , X mean), during inspiration only (R insp , X insp), and expiratory flow limitation (DeltaXrs = X insp −X exp), were calculated. FOT and 6MWD measurements were repeated at completion of rehabilitation and 3 months after completion. Results: At baseline, Xrs measures were unrelated to 6MWD. X insp improved significantly with rehabilitation (from mean(SD) −2.35(1.02) to −2.04(0.85) cmH 2 O.s.L −1 , p=0.008), while other FOT parameters did not. No FOT parameters related to the change in 6MWD at program completion. Baseline X mean, DeltaXrs, and FVC z-score correlated with the change in 6MWD between completion and 3 months after completion of rehabilitation (r s =0.62, p=0.03; r s =−0.65, p=0.02; and r s =0.62, p=0.03, respectively); with worse ventilatory impairment predicting loss of 6MWD. There were no relationships between Rrs parameters, FEV1 or FEV1/FVC z-scores and changes in 6MWD. Conclusion: Baseline reactance parameters may be helpful in predicting those patients with COPD at most risk of loss of exercise capacity following completion of pulmonary rehabilitation.

Clinical significance and applications of oscillometry

“…Oscillometric parameters likely related to gas trapping (i.e. X rs ) in patients with COPD correlated with changes in exercise capacity following completion of pulmonary rehabilitation [107]. Oscillometry may also help in the categorisation of COPD severity [108].…”

Respiratory Oscillometry in Chronic Obstructive Pulmonary Disease: Association with Functional Capacity as Evaluated by Adl Glittre Test and Hand Grip Strength Test

“…Some recent reports investigate the association of oscillometric indices with the change in 6MWT during and after pulmonary rehabilitation 26 and the exercise tolerance in COPD. 27 , 28 However, the relationships between oscillatory parameters and ADL – Glittre and the handgrip test were not evaluated, and the association of oscillometry and functional capacity is not fully understood.…”

<p>Evaluation of Exertional Ventilatory Parameters Using Oscillometry in COPD</p>

“…However, the association between each inspiratory and expiratory oscillometric parameter and ventilatory CPET parameters has never been thoroughly investigated, although the association of oscillometry with 6MWT and CPET has been previously reported. 24,25 In addition, the utility of each oscillometric parameter for evaluating and predicting exertional ventilatory parameters, including ventilatory inefficiency and exercise tolerance, has not been investigated in patients with COPD. The information obtained from oscillometry might be clinically useful for assessing the mechanisms of exercise impairment and the effects of interventions.…”