【优秀论文分享】中国康复医学会呼吸康复专业委员会第八届学术年会优秀论文分享

Changes in Respiratory Mechanics and Neural Respiratory Drive of COPD Patients during Respiratory Muscle Threshold Load Training: An Exploratory Study

Background: Patients with chronic obstructive pulmonary disease (COPD) benefits from respiratory muscle training (RMT).While most researches have investigated the effects of RMT, few have reported its physiological mechanisms.

Objective: To explore the changes in respiratory mechanics and neural respiratory drive in stable COPD patients during and after RMT.

Methods: 24 stable COPD patients were enrolled in three RMT programs sequentially:inspiratory muscle training (IMT),expiratory muscle training (EMT) and concurrent inspiratory and expiratory muscle training (CRMT). Parameters were measured at baseline, during and after each program. A subgroup analysis was performed to compare patients with and without inspiratory muscle weakness.

Results: 18 patients finished all three programs. Respiratory rate decreased during EMT and CRMT. Inspiratory time (Ti) and mean respiratory cycle time (Ttot) increased while inspiratory tidal volume (VTi) and inspiratory flow (VTi/Ti) were decreased during IMT. Expiratory time (Te) and expiratory duty ratio (Te/Ttot) were increased while expiratory tidal volume (VTe) and expiratory flow (VTe/Te) were decreased during EMT. During CRMT, Ti and Te were increased, but VTi/Ti, VTe/Te and minute ventilation (VE) were decreased. During each program, esophageal pressure, transdiaphragmatic pressure (Pdi) and root mean square of diaphragm electromyogram (RMS) were increased, while the ratio of ventilation to RMS (VE/RMS) was decreased, especially in CRMT. After each program, Ve, VTi/Ti, VTe/Te, mouth pressure, esophageal pressure, gastric pressure, Pdi, pressure-time product of Pdi, RMS, VE/RMS were increased. Patients with and without inspiratory muscle weakness benefit from both IMT and CRMT. After CRMT, VE/RMS increased in patients without inspiratory muscle weakness, yet no significant change of VE/RMS was found in patients with inspiratory muscle weakness.

Conclusions: Short-term improvements were observed in breathing pattern, diaphragmatic contractility and ventilation efficiency following RMT. All programs may be beneficial for COPD patients irrespective of their inspiratory muscle strength, with CRMT being more effective for patients without inspiratory muscle weakness.

Keywords: chronic obstructive pulmonary disease,pulmonary rehabilitation,respiratory muscle threshold load training,respiratory mechanics, neural respiratory drive

Figure1. Changes in respiratory mechanics indices of COPD patients during different models of threshold respiratory muscle training recorded from multipair esophageal electrode.

Abbreviations: SB, stable breathing, IMT, inspiratory muscle training;EMT, expiratory muscle training;CRMT, concurrent inspiratory and expiratory muscle training;; Pmo, mouth pressure;Peso,esophageal pressure;Pgas,gastric pressure;Pdi, transdiaphragmatic pressure;VT, inspiratory tidal volume;EMGdi,The diaphragm electromyogram;