Effect of a Conical-PEP Mask on Exercise in Subjects With COPD.

BACKGROUND: Dynamic hyperinflation (DH) is a major pathophysiology of COPD that is directly related to dyspnea and exercise intolerance. Positive expiratory pressure (PEP) might reduce DH and dyspnea during exercise, but at present, there is insufficient evidence to conclude whether it is beneficial for DH, dyspnea, and exercise capacity in COPD. METHODS: A randomized crossover trial with concealed allocation was conducted in 37 moderate to very severe subjects with COPD (34 males, age 66.6 ± 7.4 y, FEV1% of predicted 56.3 ± 13.7). The experimental condition was conical-PEP breathing with a PEP of around 5 cm H2O during a spot marching exercise at a constant speed, inducing 71 ± 9% age-predicted maximum heart rate to symptom limit or 25 min. The control condition was usual breathing. Exercise endurance time and end-exercise symptoms were recorded. Inspiratory capacity (IC) was measured pre-exercise and immediately post exercise. Cardiopulmonary function and breathlessness were monitored throughout the test and after 10 min of recovery. RESULTS: There were no complications or adverse effects during exercise with a conical-PEP mask. Conical-PEP showed longer exercise times than control (median 11.0 [interquartile range 7.7-17.0] min vs 8 [6.0-11.5] min, respectively, P < .001). Most stopped exercising because of breathlessness and leg fatigue. At the end of exercise, IC and breathlessness showed non-significant differences between the conditions, but breathlessness was significantly lower in conical-PEP (median 4 [1.5-5.0] than control 5 [3-6] on Borg scale at isotime for control [8 min]). CONCLUSIONS: Breathing with a 5 cm H2O conical-PEP mask improved exercise time (median 27.1% [0.6-52.9]) in subjects with COPD. The improvement in exercise with the conical-PEP mask was associated with slower development of breathlessness, possibly due to delays in DH development.

Design and Function of a New Conical Positive Expiratory Pressure Device to Be Used During Exercise.

BACKGROUND: A flow-dependent conical positive expiratory pressure (PEP) resistor incorporated into a oronasal mask was developed, which might reduce dyspnea and dynamic hyperinflation and increase exercise endurance for patients with COPD. We reported here the flow-pressure relationships and the safety and suitability of the device when used by healthy young and older subjects. METHODS: The flow-pressure relationships were determined for a range of resistors with different orifice diameters and cone lengths. A 1-cm conical-PEP device with a 6- or 7-mm orifice was used during a cycle exercise test (60% heart rate reserve) in 15 young (mean ± SD, 24.3 ± 3.9 y) and 12 older (mean ± SD, 64.4 ± 3.5 y) adults. Cardiopulmonary function and dyspnea were monitored for up to 10 min of exercise. RESULTS: For a given flow, pressure decreased as the cone length and orifice size increased. A 1-cm cone with a 6 mm orifice generated pressures of 5.24 ± 0.17 cm H2O and 18.29 ± 0.34 cm H2O at flows of 0.5 and 0.9 L/s, while for a 7 mm orifice, pressures were 4.88 ± 0.13 cm H2O and 19.14 ± 0.10 cm H2O at flows of 0.5 and 1.1 L/s, such as might occur during exercise. The choice of orifice size for a subject depended on his or her estimated expiratory flow; larger flows required the larger orifice to generate an expiratory pressure of between 5 and 20 cm H2O. Breathing with the conical-PEP device did not affect exercise time, dyspnea, minute ventilation, heart rate, or blood pressure. The SpO2 was slightly lower and PETCO2 was somewhat higher than during control exercise, but the differences were not significant. There were no adverse physiological consequences. CONCLUSIONS: A conical-PEP device of 1-cm length with an orifice of 6 or 7 mm generates effective expiratory pressure for most subjects during exercise. There were no adverse effects in healthy young and older subjects, and the device is suitable for trials with patients with COPD. (ClinicalTrials.gov registration NCT 02788370.).