Guerreiro I; Division of Pneumology, Geneva, Switzerland.
Bringard A; Weber P; Leverington V; Kharat A; Genecand L;
Taboni A; Lador F

Respiratory Physiology & Neurobiology. 341:104543, 2026 Apr.

INTRODUCTION: Dysfunctional breathing (DB) can be defined as a change in
breathing pattern associated with respiratory and/or systemic symptoms,
after ruling out underlying respiratory or cardiac disease. Recent
evidence suggests that DB contributes to dyspnea in post-COVID-19 syndrome
(PCS), as demonstrated by ventilation analysis during cardiopulmonary
exercise testing (CPET). Nevertheless, the lack of a standardized
classification for the different subtypes of DB poses challenges for
accurate diagnosis and effective management. We hypothesized that
analyzing the evolution of breathing parameters during CPET may help
classify DB into three patterns.

METHODS: We analyzed 79 CPETs performed between July 2020 and May 2022 on
patients with persistent respiratory symptoms at least three months after
COVID-19 infection. We classified patients into three different categories
based on abnormal breathing patterns: hyperventilation (HYPV), erratic
breathing (ERBR), and flattening (FLAT).

RESULTS: Age, BMI, gender and peak O2 uptake (VO2) were similar between
patterns. Compared to normal pattern (N), we found higher VE – VCO2 slope
in HYPV and FLAT, and a lower VT/ VE slope in FLAT and ERBR. The FLAT
pattern was also characterized by a higher breathing frequency at peak
exercise compared to the other patterns. ERBR and FLAT were associated
with higher symptom scores (Nijmegen Questionnaire and Dyspnea-12)
compared to N.

CONCLUSION: Analyzing the evolution of ventilatory parameters during
incremental exercise enables the classification of dysfunctional breathing
into three distinct breathing patterns: hyperventilation, erratic
breathing, and flattening.