AUTHOR=Prisca Eser , Pietro Calamai , Anja Kalberer , Laura Stuetz , Sarina Huber , Dominic Kaesermann , Sabina Guler , Matthias Wilhelm 

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

JOURNAL=Frontiers in Physiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2024.1380562

DOI=10.3389/fphys.2024.1380562

ISSN=1664-042X

ABSTRACT=<p><bold>Objectives:</bold> To assess whether nasal breathing improves exercise ventilatory efficiency in patients with heart failure (HF) or chronic coronary syndromes (CCS).</p><p><bold>Background:</bold> 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.</p><p><bold>Methods:</bold> 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.</p><p><bold>Results:</bold> Groups comprised 15 HF, CCS, and young control and 12 old control. Ventilation/carbon dioxide production (<inline-formula id="inf1"><mml:math id="m1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula><sub>E</sub>/<inline-formula id="inf2"><mml:math id="m2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula>CO<sub>2</sub>), ventilation (<inline-formula id="inf3"><mml:math id="m3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula><sub>E</sub>), breathing frequency (f<sub>R</sub>), and end-tidal oxygen partial pressure (P<sub>ET</sub>O<sub>2</sub>) were significantly lower and tidal volume and end-tidal carbon dioxide partial pressure (P<sub>ET</sub>CO<sub>2</sub>) significantly higher during nasal compared to oral breathing in all groups, with large effect sizes for most parameters. For patients with HF, median <inline-formula id="inf4"><mml:math id="m4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula><sub>E</sub>/<inline-formula id="inf5"><mml:math id="m5" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">V</mml:mi><mml:mo>˙</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula>CO<sub>2</sub> was 35% lower, f<sub>R</sub> 26% lower, and P<sub>ET</sub>CO<sub>2</sub> 10% higher with nasal compared to oral breathing, respectively. Exercise oscillatory ventilation (EOV) was present in 6 patients and markedly reduced with nasal breathing.</p><p><bold>Conclusion:</bold> 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.</p>