The Clinical And Physiological Study On Threshold Loading And Resistance Inspiratory Muscle Training In Chronic Obstructive Pulmonary Disease

Part1 Effects of two types of equal-intensity inspiratory muscle training in stable patients with chronic obstructive pulmonary disease:A short term randomised controlled trialBackground:Inspiratory muscle training（IMT）is a pulmonary rehabilitation program targeting inspiratory muscle improvement.The inspiratory training devices are classified into inspiratory resistive trainer（r-IMT）and inspiratory threshold load trainer（t-IMT）.Respiratory physiology response of the COPD to r-IMT contains inspiratory muscle force mobilization and change of the breathing pattern（deep and slow inhalation）,and the respiratory physiology response of the t-IMT only contains inspiratory muscle force mobilization.Differences in the respiratory physiology responses of COPD to the two IMT device potentially result in different lung rehabilitation effects,and it is also an important reason for the insufficient evidence of IMT in COPD.This study hypothesized that the pulmonary rehabilitation efficacy of inspiratory threshold training and inspiratory resistance training in COPD patients with inspiratory muscle weakness correlates with their respiratory physiology response.Purpose:（1）To investigate the influence of short-term inspiratory threshold load training and inspiratory resistance training on pulmonary rehabilitation related indicators in COPD,and their similarities and differences;（2）To investigate the influence of short-term inspiratory threshold load training and inspiratory resistance training on respiratory physiology changes,and their similarities and differences;（3）To explore the respiratory mechanics indicators which related to improvement of exercise tolerance after inspiratory threshold load training and inspiratory resistance training.Patients and methods:This study is a prospective randomized controlled trial.Stable COPD patients with low inspiratory muscle strength（maximum inspiratory pressure<60cm H₂O）were enrolled in the study.Subjects were divided into three groups by a simple randomization method:（1）Inspiratory resistance training group（r-IMT group,receive Inspiratory resistance training for 8 weeks）;（2）Inspiratory threshold load training group（t-IMT group,receive Inspiratory threshold load training for 8 weeks）;（3）Control group（receive no inspiratory training）.The subjects in the r-IMT group and t-IMT group need to titrate the corresponding training intensity during IMT process through the mouth pressure measurement before daily training.To ensure the pressure time product of the mouth pressure(PTP_Pm)reaches the 60%of the time pressure product of the MIP(PTP_MIP)and subjects were able to use the relevant intensity at least 15 minutes（training intensity match）.The subjects proceeded IMT for 2 times a day,15 minutes each time,followed-up after 8 weeks of IMT,and subjects should fill out the quality control sheet（matching exercise time）.Follow-up items before and after IMT included:（1）Clinical efficacy:inspiratory muscle strength（maximum inspiratory mouth pressure[MIP]）,pulmonary function（FEV1/FVC%,FEV1,FEV1%Pred,FVC%Pred）,degree of dyspnea（BDI/TDI Questionnaire）,Quality of Life（CRQ Questionnaire）.（2）Respiratory Physiology:breathing patten（breath rate[f R],total time of respiratory cycle[Ttot],inspiratory time[Ti],expiratory time[Te],percentage of inspiratory time to respiratory cycle[Ti/Ttot],percentage of expiratory time to respiratory cycle[Te/Ttot],tidal volume[Vt],minute ventilation[Ve],average inspiratory flow[Vt/Ti],average expiratory flow[Vt/Te]）,respiratory central drive（root mean square of parasternal EMG[RMSpara],maximum root mean square of parasternal EMG[RMSpara,max],corrected root mean square of parasternal EMG[RMSpara%]）,exercise capacity（maximum exercise rate of work[Wmax],anaerobic threshold[AT],oxygen uptake[V’O₂,max]）,ventilation efficacy（CO₂ ventilation equivalent[V’E/VCO₂]and ventilation-central drive coupling[Ve/i EMGpara]）,at resting and equal rate of work were measured by cardiopulmonary exercise test,respectively.Results:Seventy-five subjects who met the inclusion criteria were randomly divided into three groups:（1）Inspiratory resistance training group（r-IMT group,26 cases）;（2）Inspiratory threshold load training group（t-IMT group,24 cases）;（3）Control group（25 cases）.The clinical characteristics of the three groups were not statistically different（P>0.05）.r-IMT and t-IMT group’s IMT intensity(PTP_Pm/PTP_MIP)and daily IMT time were all matched（P>0.05）.There was no statistically significant change in pulmonary function before and after IMT（P>0.05）.In terms of curative effect,after 8weeks of IMT,the r-IMT and t-IMT group were all had an increase in MIP（P<0.05）.The increase was the same in both groups（P>0.05）;the CRQ score increased in both groups（P<0.05）,r-IMT group had greater increase in it（P<0.05）;TDI/BDI score increased in both groups（P<0.05）,r-IMT group had greater increase in it（P<0.05）;In terms of respiratory physiology,there was no significant change in respiratory physiology at rest in r-IMT and t-IMT group after 8 weeks of exercise（P>0.05）.Maximum RMSpara and maximum exercise rate of work increased in both groups（P<0.05）.Ti prolonged（P<0.05）,Vt increased（P<0.05）,RMSpara decreased（P<0.05）,V’O₂ increased（P<0.05）,V’E/VCO₂ and Ve/i EMGpara decreased（P<0.05）in r-IMT group under exercise state after 8 weeks;the t-IMT group did not have the above changes.The improvement of exercise tolerance was related to the change of ventilation-central drive coupling（Ve/i EMG）,maximum inspiratory pressure（MIP）,carbon dioxide ventilation equivalent（Ve/CO₂）,and average inspiratory flow（Vt/Ti）after short-term inspiratory resistance training,the regression equation was:W=0.37+66.99×Ve/i EMG+0.73×MIP-0.04×Ve/CO₂+3.28×Vt/Ti（P<0.05）;exercisetolerance improvement was related to the maximum inspiratory pressure（MIP）after inspiratory threshold load training,the regression equation was:W=1.67+2.91×MIP（P<0.05）;exercise tolerance improvement was related to the maximum inspiratory pressure（MIP）after inspiratory muscle training（including inspiratory threshold load training and inspiratory resistance training）,the regression equation was:W=9.37+0.14×MIP.Conclusions:（1）inspiratory resistance training and inspiratory threshold load training both improved exercise tolerance,inspiratory muscle strength,quality of life,dyspnea in COPD;Inspiratory resistance training improves quality of life and dyspneamore effectively than inspiratory threshold load training.（2）Respiratory physiology mechanism:exercise tolerance after inspiratory resistance training and inspiratory threshold load training were related to the increase of inspiratory muscle strength reserve,and exercise tolerance improvement after inspiratory resistance training was also related to the deep-slow breathing mode and the improvement of ventilation effectiveness.Part2 Relationship between surface respiratory electromyography and transesophageal diaphragmatic electromyography during treadmill exercise in stable patients with COPDBackground:In the first part of this study,non-invasive surface parasternal electromyography was used as a new objective indicator for evaluation of exertional dyspnea before and after inspiratory muscle training in COPD.Traditionally,transesophageal diaphragm electromyography（es EMGdi）measurement in cardiopulmonary exercise tests is a reliable evaluation method for respiratory central drive and dyspnea,but it is invasive and complicated.The surface respiratory electromyography is non-invasive and easy to use.However,the previous research conditions were that in the resting state,the reliability of various surface respiratory activities measurements under exercise conditions has not been described.Purpose:（1）Non-invasive surface respiratory electromyography and invasive transesophageal diaphragmatic electromyography testing was used to investigate the different types of respiratory muscles during treadmill exercise in COPD;（2）This study evaluated the relationship between non-invasive surface respiratory EMGs and transesophageal diaphragmatic EMGdi measurements during treadmill exercise,investigating whether surface respiratory EMGs can correctly reflect the respiratory center drive and external dyspnea during treadmill exercise.Patients and methods: Transesophageal diaphragmatic electromyogram（es EMGdi）and surface inspiratory electromyographys（sur EMGs）,including surface diaphragmatic EMG（sur EMGdi）,surface parasternal intercostal muscle EMG（sur EMGpara）and surface sternocleidomastoid EMG（sur EMGsc）,were measured simultaneously in both statble COPD subjects and healthy subjects during treadmill exercise.Each inspiratory EMG（es EMGdi,sur EMGpara,and EMGsc）was quantified using root mean square（RMS）and expressed as es RMSdi,sur RMSpara,and sur RMSsc,respectively.The changing characteristics of es RMSdi,sur RMSpara,and sur RMSsc in COPD subjects and healthy subjects during treadmill exercise were separately described.Calculating non-linear fitting relationship between es RMSdi and es RMSdi,sur RMSpara,and sur RMSsc.Results: 20 COPD subjects and 17 healthy subjects were enrolled in this study.The respiratory EMG changing of COPD subjects and healthy subjects during the treadmill exercise were similar.sur EMGdi was affected by the muscle activity.However,the records of es EMGdi,sur EMGpara,and sur EMGsc showed little disturbance and could be clearly displayed.es EMGdi,sur EMGpara,and sur EMGsc show an increasing trend as exercise rate of work increased.Both es EMGdi and sur EMGpara showed a “S” increase during treadmill exercise（small increase in early stage of exercise,rapidly increased in mid-motion,and relatively slow increase in later period）.However,sur EMGsc increased exponentially and did not show a statistically significant increase during the first half of the exercise.Mobilization of sur EMGsc was relatively late during the exercise.In the latter half of the exercise,sur EMGsc increased more than sur EMGpara.The relationship between es EMGdi and sur EMGpara in healthy subjects with normal pulmonary function during treadmill exercise: the coefficient of determination r²=0.95,the correlation coefficient was r=0.97,P<0.01.The relationship between es EMGdi and sur EMGsc in healthy subjects during treadmill exercise: the coefficient of determination r²=0.91,the correlation coefficient was r=0.95,P<0.01.The relationship between es EMGdi and sur EMGpara in subjects with chronic obstructive pulmonary disease during treadmill exercise: the coefficient of determination r²=0.97,the correlation coefficient was r=0.98,P<0.01.The relationship between es EMGdi and sur EMGsc in subjects with chronic obstructive pulmonary disease during treadmill exercise: the coefficient of determination r²=0.96,the correlation coefficient was r=0.98,P<0.01.Conclusion: Both the measurement of sur EMGpara and sur EMGsc can be used as indicators for evaluation of respiratory central drive and dyspnea during exercise in COPD.The sur EMGpara reflect the respiratory central drive and dyspnea more correctly.