Characterization of dysfunctional breathing using cardiopulmonary exercise testing

FIGURE 1. Examples of the utility of panel 4 and 7 in the Wasserman 9 panel‐plot in distinguishing between normal and different dysfunctional breathing responses to increasing exercise. Panel 4 plots VCO2 against minute ventilation (VE) allowing interpretation of ventilatory efficiency (VE/VCO2 slope). Panel 7 plots both breathing frequency (Bf) and tidal volume (Vt) against increasing minute ventilation, enabling visualization of exercise breathing responses. (a) Normal response – Normal VE/VCO2 slope and appropriate increases in Vt and Bf. (b) Isolated BPD – Normal VE/VCO2 slope but highly erratic changes in Vt and Bf. (c) Isolated HV – Raised VE/VCO2 slope but appropriate increase in Vt and Bf (d) Combined BPDHV – Raised VE/VCO2 slope and highly erratic changes in Vt and Bf.

FIGURE 2. Flowchart depicting the identification of the four study groups and the prevalence of dysfunctional breathing within the referral population.

FIGURE 3. Box plot depicting VE/VCO2 data for each study group. The median, quartiles, minimum, maximum, and outliers are indicated. Significant pairwise comparisons as determined by post‐hoc DSCF tests are indicated with their associated p‐values.

FIGURE 4. Box plot depicting Peak VO2 data for each study group. The median, quartiles, minimum, maximum, and outliers are indicated. Significant pairwise comparisons as determined by post‐hoc DSCF tests are indicated with their associated p‐values.

FIGURE 5. Stacked bar chart depicting the distribution of functional impairment for each study group according to the Weber classification. The relative percentage of patients in classes (a–d) for each study group are denoted by the different shades of blue.

FIGURE 6. The relationship between VE/VCO2 and Peak VO2. Each study group is denoted as follows: = Normal, = BPD, = HV, = BPDHV. Regression lines are also presented.