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. 2020 Apr:164:105900.
doi: 10.1016/j.rmed.2020.105900. Epub 2020 Feb 25.

Cardiopulmonary exercise test indices of respiratory buffering before and after aerobic exercise training in women with pulmonary hypertension: Differentiation by magnitudes of change in six-minute walk test performance

Z V Morris  1 , L M K Chin  2 , L Chan  2 , A A Guccione  3 , A Ahmad  2 , R E Keyser  4
Affiliations

Cardiopulmonary exercise test indices of respiratory buffering before and after aerobic exercise training in women with pulmonary hypertension: Differentiation by magnitudes of change in six-minute walk test performance

Z V Morris et al. Respir Med. 2020 Apr.

Abstract

While aerobic exercise training (AET) has generally been shown to improve 6-min walk test (6MWT) distance (6MWD) in patients with pulmonary hypertension (PH), a substantial number of patients appear to adapt differently, with minimal or even negative changes in 6MWT distance being reported.

Purpose: To compare post-aerobic exercise training adaptations in cardiorespiratory functional capacity across three groups of patients with PH: those with high (HI), low (LI) and negative (NEG) post-training increases in 6MWD.

Methods: Participants were 25 females (age 54 ± 11 years; BMI 31 ± 7 kg/m2) who completed a vigorous, 10-week, thrice weekly, supervised treadmill walking exercise program. Cardiopulmonary exercise tests (CPET) and 6MWT were completed before and after training. Ten of the 25 participants were classified as HI (range = 47-143 m), 11 were classified as LI (range = 4-37 m) and 4 were classified as NEG (range = -17 to -53 m).

Results: Peak CPET duration, WR and time to anaerobic threshold (AT) were significantly higher (p < 0.05) after training in both the LI and HI groups but not in the NEG group. There was a significant improvement in VE/VCO2 (p = 0.042), PETCO2 (p = 0.011) and TV (p = 0.050) in the HI group after training, but not in the NEG or LI group.

Conclusion: These findings suggest that sustained ventilatory inefficiency and restricted respiratory buffering may mediate exercise intolerance and impede the ability to adapt to exercise training in some patients with PH.

Keywords: Aerobic exercise training; Pulmonary hypertension; Six-minute walk test.

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Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Figure 1:
Figure 1:
Changes in 6MWT after AET. Horizontal dashed line represents 6MWT MCID. NEG formula image, LI formula image, HI formula image. 6MWT = six-minute walk test; MCID = minimal clinically important difference.
Figure 2:
Figure 2:
Changes in CPET duration (A), peak WR (B), peak VO2 (C), time at AT (D) and VO2 at AT (E) for NEG, LI and HI before formula image and after AET formula image. P-values represent significant differences within each of the groups post vs pre AET. CPET = cardiopulmonary exercise test; WR = work rate; VO2 = peak oxygen consumption; AT = anaerobic threshold; AET = aerobic exercise training.
Figure 3:
Figure 3:
Changes in VE/VCO2 (A), PETCO2 (B), VE (C), VCO2 (D) and tidal volume (E) for NEG, LI and HI before AET formula image and after AET formula image. P-values represent significant differences within each of the groups post vs pre AET.VE/VCO2 = ventilatory quotient for carbon dioxide; PETCO2 = end tidal partial carbon dioxide pressure; VE = expired minute ventilation, VCO2 = expired volume of carbon dioxide.
Figure 4:
Figure 4:
Correlation between changes in 6MWD and VE/VCO2 (A), PETCO2 (B) and time at AT (C) for the NEG formula image, LI formula image and HI formula image groups. 6MWD = 6-minute walk distance; VCO2 = ventilatory quotient for carbon dioxide; PETCO2 = end tidal carbon dioxide partial pressure; AT = anaerobic threshold.
See this image and copyright information in PMC

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