Exercise Oscillatory Ventilation: Interreviewer Agreement and a Novel Determination

Abstract

Introduction: Determination of exercise oscillatory ventilation (EOV) is subjective, and the interreviewer agreement has not been reported. The purposes of this study were, among patients with heart failure (HF), as follows: 1) to determine the interreviewer agreement for EOV and 2) to describe a novel, objective, and quantifiable measure of EOV.

Methods: This was a secondary analysis of the HEART Camp: Promoting Adherence to Exercise in Patients with Heart Failure study. EOV was determined through a blinded review by six individuals on the basis of their interpretation of the EOV literature. Interreviewer agreement was assessed using Fleiss kappa (κ). Final determination of EOV was based on agreement by four of the six reviewers. A new measure (ventilation dispersion index; VDI) was calculated for each test, and its ability to predict EOV was assessed with the receiver operator characteristics curve.

Results: Among 243 patients with HF (age, 60 ± 12 yr; 45% women), the interreviewer agreement for EOV was fair (κ = 0.303) with 10-s discrete data averages and significantly better, but only moderate (κ = 0.429) with 30-s rolling data averages. Prevalence rates of positive and indeterminate EOVs were 18% and 30% with the 10-s discrete averages and 14% and 13% with the 30-s rolling averages, respectively. VDI was strongly associated with EOV, with areas under the receiver operator characteristics curve of 0.852 to 0.890.

Conclusions: Interreviewer agreement for EOV in patients with HF is fair to moderate, which can negatively affect risk stratification. VDI has strong predictive validity with EOV; as such, it might be a useful measure of prognosis in patients with HF.

Trial registration: ClinicalTrials.gov NCT01658670.

Figures

Figure 1. Visual example of the ventilation dispersion area

The black line with round markers represents the ventilation based on data averaged using 30-s rolling intervals. The red dashed line with square markers represents the mean ventilation for the 30 s before and after each of these intervals. The gray shaded areas marked with “D” represent the difference between the ventilation and the mean ventilation at each interval. The total dispersion area is the sum of D1 + D2 + ⋯ + D10.

Figure 2. Distribution of ventilation dispersion index (VDI)

Left pane shows the absolute VDI values. Right pane shows the Log10 of VDI.