Abstract
BACKGROUND: Conical-positive expiratory pressure (conical-PEP) has been applied during exercise to improve exercise capacity, dynamic hyperinflation (DH), and dyspnea in COPD. However, evidence remains limited regarding the individualized selection of its resistor (orifice size) and its effects on exercise duration, DH development, and dyspnea. METHOD: A randomized crossover trial was conducted to evaluate the effects of conical-PEP. Participants performed spot marching exercise while breathing through a conical-PEP device with a mask, compared to a sham-PEP condition in which a similar mask was worn without the conical-PEP component. The conical-PEP resistor was selected to achieve the minimum required PEP level, calculated by the proposed formula, while ensuring that pressure did not exceed 35 cmH₂O. Exercise endurance time, end-exercise inspiratory capacity (IC) to assess DH, and dyspnea using the modified Borg scale were recorded. RESULTS: Twenty moderate to severe COPD subjects (19 male, 1 female, age 67.40 ± 8.22 years, FEV1% predicted 56.05 ± 16.90) participated. Conical-PEP resulted in longer exercise time (4.98 ± 2.97 minutes) than sham-PEP (3.99 ± 2.19 minutes, p = 0.004). End-exercise IC was significantly better in conical-PEP (1.51 [1.24, 1.85] L) than sham-PEP (1.42 [1.16, 1.84] L, p = 0.020). Dyspnea was significantly lower in conical-PEP at iso-time (4 [4, 5]) compared to sham-PEP (5 [5, 6], p = 0.005), though no significant difference was found at end exercise. CONCLUSION: Conical-PEP with minimum required PEP level improves exercise capacity, delays DH development, and delays dyspnea onset in COPD patients.