Improved exercise ventilatory efficiency with nasal compared to oral breathing in cardiac patients

Objectives: To assess whether nasal breathing improves exercise ventilatory efficiency in patients with heart failure (HF) or chronic coronary syndromes (CCS).Background: Exercise inefficient ventilation predicts disease progression and mortality in patients with cardiovascular diseases. In healthy people, improved ventilatory efficiency with nasal compared to oral breathing was found.Methods: Four study groups were recruited: Patients with HF, patients with CCS, old (age≥45 years) and young (age 20–40 years) healthy control subjects. After a 3-min warm-up, measurements of 5 min with once nasal and once oral breathing were performed in randomized order at 50% peak power on cycle ergometer. Ventilation and gas exchange parameters measured with spiroergometry were analysed by Wilcoxon paired-sample tests and linear mixed models adjusted for sex, height, weight and test order.Results: Groups comprised 15 HF, CCS, and young control and 12 old control. Ventilation/carbon dioxide production (V˙E/V˙CO2), ventilation (V˙E), breathing frequency (fR), and end-tidal oxygen partial pressure (PETO2) were significantly lower and tidal volume and end-tidal carbon dioxide partial pressure (PETCO2) significantly higher during nasal compared to oral breathing in all groups, with large effect sizes for most parameters. For patients with HF, median V˙E/V˙CO2 was 35% lower, fR 26% lower, and PETCO2 10% higher with nasal compared to oral breathing, respectively. Exercise oscillatory ventilation (EOV) was present in 6 patients and markedly reduced with nasal breathing.Conclusion: Nasal breathing during submaximal exercise significantly improved ventilatory efficiency and abnormal breathing patterns (rapid shallow breathing and EOV) in 80% of our patients with HF and CCS.