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

Abstract

Background: Oscillometry is a tool to measure respiratory impedance that requires minimal patients' effort. In patients with chronic obstructive pulmonary disease (COPD), the correlation of respiratory impedance at rest with exertional ventilatory parameters, including exercise tolerance, has scarcely been reported. In addition, the utility of oscillometric parameters might differ between the inspiratory and expiratory phases due to airflow obstruction during expiration, but the hypothesis had not been validated. The aim of the present study was to investigate whether oscillometric parameters are associated with exertional ventilatory parameters in patients with COPD. Methods: Fifty-five subjects with COPD who attended clinics at the National Hospital Organization Osaka Toneyama Medical Center performed spirometry, oscillometry, and cardiopulmonary exercise testing (CPET) within 2 weeks. The correlations between parameters of spirometry, oscillometry, and CPET were analyzed using Spearman's rank correlation coefficient, univariate, and multivariate analyses. Results: Respiratory reactance had better correlations with the CPET parameters than respiratory resistance. Moreover, inspiratory reactance at rest correlated with the CPET parameters stronger than expiratory reactance. In particular, inspiratory resonant frequency (Fres-ins) correlated with peak oxygen uptake (r S =−0.549, p<0.01) and dead space to tidal volume ratio at peak exercise (r S =0.677, p<0.01) and the best predicted expiratory tidal volume (V T ex) at peak exercise of all the oscillometric parameters (r S =−0.679, p<0.01). However, the correlation between Fres-ins and V T ex at peak exercise became weak in subjects with severe and very severe COPD during exercise. Conclusion: Measurement of respiratory reactance is useful for the effortless evaluation of not only exertional ventilatory parameters but exercise tolerance in patients with COPD. The correlation of respiratory impedance with exertional ventilatory parameters can become weak in patients with advanced COPD; thus, the measurement of oscillometry might not be appropriate for evaluating exertional ventilatory parameters of patients with advanced COPD.

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

“…These results also reflect Zeng et al, 28 who recently found correlations between resistive and reactive parameters with 6MWD in COPD. They are also in line with that obtained by Yamamoto et al 45 The authors observed that oscillometric parameters correlated with exertional ventilatory parameters and reflected exercise tolerance in COPD subjects during cycle ergometer tests. Similar results were also observed in adults with sickle cell anemia, analyzing the correlations among 6MWD and oscillometric parameters.…”

Respiratory Oscillometry and Functional Performance in Different COPD Phenotypes

“… 64 The results are also consistent with that obtained recently using the 6-minute walking distance 65 , 66 and during cycle ergometer tests. 67 These associations agree with the involved physiology, describing an increase in ADL-Glittre test time with airway obstruction and Cdyn reduction. This reflects the systemic effects due to lung abnormalities, including the presence of airflow limitation and dynamic hyperinflation.…”

Associations of Exercise Tolerance and Clinical Parameters in Japanese Patients With Chronic Obstructive Pulmonary Disease: Impact of Skeletal Muscle

“…1b). The severity of COPD predicted by %FEV 1 is also related to the decrease of exercise tolerance, and Yamamoto et al reported that V O2 at peak exercise was significantly higher in COPD patients in GOLD stages I and II than in those in GOLD stages III and IV 14 . The current results also showed that the level of V O2 at peak exercise tended to be decreased depending on the GOLD stage, except for stage I (Fig.…”

“…Decreasing exercise tolerance, normally measured by the 6-minute walk test or cardiopulmonary exercise testing (CPET), is one of the important clinical features related to a poor prognosis in COPD patients 3,9,10 , and with CPET one can evaluate exercise tolerance with exertional ventilatory parameters precisely and safely 11,12 . For example, oxygen uptake (V O2 ) at peak exercise, which represents exercise tolerance, is significantly correlated with FEV 1 and %FEV 1 reflecting the severity of COPD 13,14 . Notably, with CPET, one can detect physical problems including cardiac dysfunction and functional skeletal muscle disorders during the test, which contributes to rapid initiation of treatment 15 .…”