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Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise
Published on: February 20, 2017
[Exercise tolerance in relation to ventilatory drive and respiratory muscle function in COPD]
1Institute of the Respiratory Disease, China Medical University, Shenyang 110001, China.
Objective:
To assess the relationships between exercise tolerance and respiratory drive and respiratory muscle function in COPD.
Methods:
28 patients with COPD and 26 normal subjects were involved in the study. Routine pulmonary function, pulmonary diffusing capacity, P0.1, PImax were measured at rest. Oxygen consumption (VO2), carbon dioxide production (VCO2), minute ventilation (VE) etc were measured during exercise testing. Borg Scale was recorded simultaneously. Arterial blood gases were measured before and after exercise.
Results:
(1) PImax in COPD group (40 +/- 15 mm Hg) was significantly lower than that in the normal group [(53 +/- 19) mm Hg, P < 0.05]. P0.1 in COPD group [(2.8 +/- 0.9) mm Hg] was significantly higher than that in the normal group [(2.0 +/- 0.7) mm Hg, P < 0.05]. Inspiratory drive efficacy (VT/P0.1) in COPD group [(0.21 +/- 0.04) L/mm Hg] was significantly lower than that in the normal group [(0.28 +/- 0.07) L/mm Hg, P < 0.05]. P0.1/PImax in COPD group was (0.069 +/- 0.021), significantly higher than that in the normal group [(0.037 +/- 0.009), P < 0.01]. (2) VO2max was correlated with P0.1/Pimax and Borg Scale in COPD patients (r = 0.66, P < 0.01, and r = 0.53, P < 0.05 respectively). Borg Scale was also positively correlated with P0.1/PImax in COPD group (r = 0.49, P < 0.05).
Conclusion:
In addition to airway obstruction and the damaged gas exchange, exercise intolerance in COPD may also be related to the increased respiratory drive and dysfunction of respiratory muscle.
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