Observations of Late-Onset Exercise Oscillatory Ventilation

Abstract

Exercise oscillatory ventilation (EOV) is characterized by regular waxing and waning of ventilation without apnea during exercise. In patients with heart failure (HF) development of EOV is a robust predictor of mortality. EOV is typically reported during the early stages of exercise and dissipates during the later stages of exercise. We have recently identified a cohort of diagnostically diverse patients that present EOV during the late stages of exercise. This late-onset pattern is contradictory to the common pattern of EOV, thus we termed it late-onset EOV. PURPOSE: To retrospectively analyze clinical characteristics, demographics and breathing patterns of patients who presented with late-onset EOV. METHODS: The medical records of eleven patients (6M/5F, 53±19 yrs, BMI: 29±12 kg/m2) demonstrating late-onset EOV during clinically indicated cardiopulmonary exercise testing were retrospectively analyzed. The amplitude of cycles were calculated as peak VE minus nadir VE during each cycle. The period of each cycle was calculated measuring the time from nadir to nadir. VE/VCO2 slope was calculated as (VEpeak – VErest)/(VCO2peak – VCO2rest). Late-onset EOV was defined as ≥3 amplitudes of ≥ 25% of the average VE for 3 consecutive cycles with the EOV originating ≥50% VO2 peak. RESULTS: Diagnoses included heart failure (n=6), diabetes (n=4), exercise induced arrhythmia (n=7), hypertension (n=4) and hyperlipidemia (n=4) and medications included beta-blockers (n=7), aspirin (n=6), diuretics (n=5) and statins (n=5); however, no diagnosis or medication were common across all patients. The VO2 peak was 20±7 mL/kg/min (72±28% predicted VO2peak). None of the patients demonstrated oscillatory ventilation at rest, while all of the patients exhibited EOV at >50% VO2 peak (amplitude of mean VE=44.7%, period=40.4s). VE/VCO2 slope had a positive correlation with EOV amplitude (r=0.74, p=0.01). The % predicted VO2 peak had a negative relationship with EOV period (r= -0.64, p=0.04). CONCLUSION: Our data demonstrate, in a diverse patient population, that the onset of EOV can occur during late stages of exercise and is related to metrics of exercise intolerance. No clear diagnosis or medication was common among these patients. Additional research is required to elucidate the mechanisms contributing to late-onset EOV.