Cardiopulmonary exercise testing to indicate increased ventilatory variability in subjects with dysfunctional breathing.

BACKGROUND: Dysfunctional breathing (DB) is a common, but largely underappreciated, cause of chronic dyspnoea. Under visual inspection, most subjects with DB present with larger sequential changes in ventilation (V̇E) and breathing pattern (tidal volume (VT) and breathing frequency (f)) before and/or during incremental cardiopulmonary exercise testing (CPET). Currently, however, there are no objective criteria to indicate increased ventilatory variability in these subjects. METHODS: Twenty chronically dyspnoeic subjects with DB and 10 age- and sex-matched controls performed CPET on a cycle ergometer. Cut-offs to indicate increased V̇E, VT, f, and f/VT ratio variability (Δ = highest-lowest 20 s arithmetic mean) over the last resting minute (rest ), the 2sd min of unloaded exercise (unload ), and the 3rd min of loaded exercise (load ) were established by ROC curve analyses. RESULTS: Subjects with DB presented with increased V̇E, higher ventilatory variability, higher dyspnoea burden, and lower exercise capacity compared to controls (p < 0.05). ΔV̇Eload (>4.1 L/min), Δfrest (>5 breaths/min; bpm), Δfunload (>4 bpm), Δfload (>5 bpm), Δf/VTrest (>4.9 bpm/L), and Δf/VTload (>1.3 bpm/L) differentiated DB from a normal pattern (areas under the curve ranging from 0.729 to 0.845). High Δf, in particular, was associated with DB across all CPET phases. CONCLUSIONS: This study provides objective criteria to indicate increased ventilatory variability during incremental CPET in dyspnoeic subjects with DB. Large variability in breathing frequency seems particularly useful in this context, a finding that should be prospectively confirmed in larger studies.

Aerobic Exercise Increases Vascular Diameter of Arteriovenous Fistula in Hemodialysis Patients.

INTRODUCTION: A healthy arteriovenous fistula (AVF) depends on adequate vessel diameter which can be maintained through aerobic exercises. A randomized crossover study was conducted to evaluate the acute effects of aerobic exercise on a cycle ergometer on AVF vascular diameter, through ultrasound, and on blood pressure (BP). METHODS: Eight hemodialysis (HD) patients completed 2 different occasions in random order with a 7-day washout: (a) exercising moment, in which 30-min aerobic exercise was performed on a cycle ergometer; and (b) resting moment, which was performed 30-min with the patient sitting in a chair. Both occasions were evaluated 1-h before the second weekly HD day. RESULTS: A significant increase in AVF vascular diameter induced by 30-min aerobic exercise was found (1.15 ± 0.56 to 1.47 ± 0.66 cm; p = 0.042), whereas systolic (p = 0.105) and diastolic BP (p = 0.366) did not change. CONCLUSIONS: We can conclude that acute aerobic exercise was shown to be effective in improving the AVF vascular diameter in HD patients. The aerobic exercise benefits in endothelium-dependent vasodilation which may be an effective, practical, and economic strategy to maintain AVF patency.