Ventilation Dispersion Index as an Objective Evaluation Tool of Exercise Oscillatory Ventilation in Patients With Heart Failure.

BACKGROUND: Exercise oscillatory ventilation (EOV) is related to worse prognosis in patients with heart failure (HF). However, its determination is subjective and there is no standard measure to identify it. The aim of the study was to evaluate and characterize the EOV of patients with HF using the ventilation dispersion index (VDI). METHODS AND RESULTS: Patients underwent cardiopulmonary exercise testing (CPX), EOV was assessed by 2 reviewers and the VDI was calculated. The receiver operator curve analysis was used to assess the ability of the VDI to predict EOV. Pearson's correlation test was performed to determine the relationship between VDI and CPX variables. Forty-three patients with HF underwent CPX and were divided into 2 groups: with a VDI of less than 0.601 and a VDI of 0.601 or greater. An area under the curve of 0.759 was observed in the receiver operator curve analysis between VDI and EOV (P = .008). The VDI showed a significant correlation with the ventilatory CPX variables. According to the cut-off point obtained on the receiver operator curve, patients with a VDI of 0.601 or greater had lower left ventricular ejection fraction and higher values of resting minute ventilation and peak minute ventilation. CONCLUSIONS: The VDI proved to be a good predictor of EOV in patients with HF.

Oxygen uptake efficiency slope as a useful measure of cardiorespiratory fitness in morbidly obese women.

Cardiopulmonary assessment through oxygen uptake efficiency slope (OUES) data has shown encouraging results, revealing that we can obtain important clinical information about functional status. Until now, the use of OUES has not been established as a measure of cardiorespiratory capacity in an obese adult population, only in cardiac and pulmonary diseases or pediatric patients. The aim of this study was to characterize submaximal and maximal levels of OUES in a sample of morbidly obese women and analyze its relationship with traditional measures of cardiorespiratory fitness, anthropometry and pulmonary function. Thirty-three morbidly obese women (age 39.1 ± 9.2 years) performed Cardiopulmonary Exercise Testing (CPX) on a treadmill using the ramp protocol. In addition, anthropometric measurements and pulmonary function were also evaluated. Maximal and submaximal OUES were measured, being calculated from data obtained in the first 50% (OUES50%) and 75% (OUES75%) of total CPX duration. In one-way ANOVA analysis, OUES did not significantly differ between the three different exercise intensities, as observed through a Bland-Altman concordance of 58.9 mL/min/log(L/min) between OUES75% and OUES100%, and 0.49 mL/kg/min/log(l/min) between OUES/kg75% and OUES/kg100%. A strong positive correlation between the maximal (r = 0.79) and submaximal (r = 0.81) OUES/kg with oxygen consumption at peak exercise (VO2peak) and ventilatory anaerobic threshold (VO2VAT) was observed, and a moderate negative correlation with hip circumference (r = -0.46) and body adiposity index (r = -0.50) was also verified. There was no significant difference between maximal and submaximal OUES, showing strong correlations with each other and oxygen consumption (peak and VAT). These results indicate that OUES can be a useful parameter which could be used as a cardiopulmonary fitness index in subjects with severe limitations to perform CPX, as for morbidly obese women.