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

Area of Science:

• Pulmonary Physiology
• Exercise Medicine
• Respiratory Diagnostics

Background:

• Dysfunctional breathing (DB) is an underrecognized cause of chronic dyspnea.
• Individuals with DB often exhibit significant ventilatory and breathing pattern changes during exercise.
• Objective criteria for identifying increased ventilatory variability in DB are currently lacking.

Purpose of the Study:

• To establish objective criteria for detecting increased ventilatory variability during incremental cardiopulmonary exercise testing (CPET) in individuals with DB.
• To differentiate between subjects with DB and healthy controls based on ventilatory patterns during CPET.

Main Methods:

• Twenty individuals with chronic dyspnea and DB and 10 healthy controls underwent CPET.
• Variability in ventilation (V̇E), tidal volume (VT), and breathing frequency (f) was assessed using the highest-lowest 20-second mean during resting, unloaded, and loaded exercise phases.
• Receiver operating characteristic (ROC) curve analyses were used to determine cut-off values for increased variability.

Main Results:

• Subjects with DB showed increased V̇E, higher ventilatory variability, greater perceived dyspnea, and reduced exercise capacity compared to controls.
• Specific cut-off values for variability in V̇E, f, and the f/VT ratio during different CPET phases were identified.
• Increased variability in breathing frequency (Δf) was strongly associated with DB across all exercise stages.

Conclusions:

• This study presents objective criteria for identifying increased ventilatory variability in dyspneic individuals with DB during CPET.
• Breathing frequency variability appears to be a particularly useful indicator for DB.
• Further prospective validation in larger cohorts is recommended.