| [Background]Chronic obstructive pulmonary disease(COPD)is a chronic respiratory disease characterized by high morbidity,mortality and disability,and has become an important public health problem in the world.The persistent air flow limitation(EFL)of COPD may result in dynamic pulmonary hyperinflation(DPH)and intrinsic positive end-expiratory pressure(PEEPi),and ultimately lead to respiratory muscle dysfunction and dyspnea.Pulmonary rehabilitation has become the important non-drug treatment for COPD patients.Respiratory muscle training is one of the main components in pulmonary rehabilitation.However,most researchers focused on effects of rehabilitation before and after training.The physiology mechanism behind respiratory rehabilitation remains unclear.It has great realistic significance to understand how pulmonary rehabilitation alters the respiratory abnormality according to the basic respiratory physiology of COPD.[Objective]This study aims to compare the changes of respiratory mechanics and neural respiratory drive in stable COPD patients and normal subjects during and after different respiratory muscle threshold load training,including inspiratory muscle training(IMT),expiratory muscle training(EMT)and concurrent inspiratory and expiratory muscle training(CRMT).We hope to explored the physiological mechanism of COPD patients doing the different respiratory muscle threshold load training,and to provide evidence about respiratory muscle training in patients with COPD.[Methods]Study groupings and interventions:24 stable COPD patients and 9 normal subjects were randomly assigned to three different sequence training groups according to the Latin square design:Group A:IMT-EMT-CRMT;Group B:EMT-CRMT-IMT;Group C:CRMT-IMT-EMT.The 30%maximum inspiratory pressure(MIP)and 15%maximum expiratory pressure(MEP)were set as the threshold load for IMT,EMT and CRMT respectively.Participates were exercising for 3 minutes and rest 5 minutes at each trainer.Data acquisition was carried out with Powerlab systems and Chart7 software and monitoring parameters before exercise,during exercise and after exercise according to the exercise sequence.Monitoring paraments:Basic information tests such as lung function testing,six-walking distance and respiratory muscle strength were performed.Esophageal(Peso)and gastric pressure(Pgas)were measured with balloon-tipped catheters.Diaphragm electromyogram(EMGdi)were measured with multi-pair esophageal electrodes.Flow and mouth pressure(Pmo)were also recorded at the same time.Calculating paraments:(1)Respiratory rate(RR),mean respiratory cycle time(Ttot),inspiratory time(Ti),expiratory time(Te),inspiratory duty ratio(Ti/Ttot),expiratory duty ratio(Te/Ttot),inspiratory tidal volume(VTi),expiratory tidal volume(VTe),inspiratory flow(VTi/Ti),expiratory flow(VTe/Te),inspired minute ventilation(VE)and inspiratory capacity(IC)were calculated from the flow record.(2)Mouth pressure(Pmo),esophageal(Peso)and gastric pressure(Pgas),transdiaphragmatic pressure(Pdi),diaphragm tension time index(TTdi)and pressure-time product of Pmo and Pdi(PTPmo,PTPdi).(3)The root mean square(RMS)EMG and the ratio of ventilation to the EMGdi(VE/RMS).The changes of the respiratory mechanics and neural respiratory drive in stable COPD patients and normal subject during and after different respiratory muscle threshold load training were compared.We also perform a subgroup analysis to determine the effects after the different respiratory muscle threshold load training on patients with and without respiratory muscle weakness.[Results]1.The baseline characteristics of participatesOf the 24 COPD patients and 9 normal subjects initially included in the study,six COPD patients dropped out,and the remaining 18 patients and 9 normal subjects successfully completed the study.Baseline characteristics of the three groups were of no significant difference,such as static pulmonary function,six-walking distance and respiratory muscle strength.The average PImax of COPD patients was 59.74±16.58 cmH2O and PEmax was 58.20±21.73 cmH2O.The average PImax of normal subjects was 77.53±19.22 cmH2O and the average PEmax was 76.32±9.12 cmH2O.2.Changes of respiratory physiology during different respiratory muscle training.In COPD patients,RR decreased significantly during EMT and CRMT.Ti and Ti/Ttot increased significantly in IMT(P<0.05).Te and Te/Ttot were significantly increased in EMT(P<0.05).Ti and Te were increased in CRMT,but no change in Ti/Ttot was detected.VTi/Ti was decreased in IMT and VTe/Te was decreased in EMT.VTi/Ti,VTe/Te and VE were all significantly decreased in CRMT(P<0.05).IC was decreased in EMT.In normal subjects,RR decreased significantly during training(P<0.05).While Ti,Ti/Ttot increased significantly during IMT,there was no significant change in Te,Te/Ttot during EMT,Ti and Te increased significantly during CRMT,and Ti/Ttot did not change significantly.VTi increased during EMT(P<0.05),and there was no significant change in IC.There were significant increases of Pmo in COPD patients during IMT,EMT and CRMT(P<0.05).The increased Pmo was similar to the setted threshold pressure.Peso and Pdi were all significantly increased(P<0.05)in IMT,EMT and CRMT.Both TTdi,PTPmo and PTPdi were increased significantly during the inspiratory of IMT and CRMT(P<0.05).PTPmo were also increased significantly during the expiratory of EMT and CRMT(P<0.05).The trend of changes of these indices in normal subjects were similar to COPD patients.There were significantly increases of RMS and decreases of VE/RMS during IMT,EMT and CRMT in COPD patients.In normal subjects,the RMS were significantly increased only during IMT and CRMT,and the VE/RMS were also significantly decreased(P<0.05).3.Changes of respiratory physiology after the different respiratory muscle training.In COPD patients,there were significantly increases of RR,along with the decreases of Ti after IMT and EMT.Te decreased significantly(P<0.05)after EMT.There was no significant change in RR,Ti,and Te after CRMT.Ti/Ttot significantly decreased after IMT(P<0.05).There was no significant change of in Ti/Ttot after EMT and CRMT.VTi increased significantly after IMT and CRMT(P<0.05).VE,VTi/Ti,and VTe/Te were all increased significantly after three respiratory muscle trainings(P<0.05).In normal subjects,RR were significantly decreased after three respiratory muscle trainings.Both Ti and Te were significantly increased after EMT and CRMT.Ti/Ttot was decreased significantly after IMT(P<0.05).There were no significant changes in VE,VTi/Ti,and VTe/Te after all trainings.There were significant increases of Pmo,Peso,Pgas,Pdi,TTdi,and PTPdi after IMT and CRMT in COPD patients(P<0.05).In normal subjects,Pmo,Peso,Pdi,and PTPdi were increased significantly after all trainings(P<0.05),but no changes in Pgas and TTdi.There were significant increases of RMS and VE/RMS after all trainings in COPD patients(P<0.05).In normal subjects,no changes had been found in RMS or VE/RMS after all trainings.4.Difference of physiological parameters in patients with and without respiratory muscle weakness after trainings.We performed a subgroup analysis to determine the difference of physiological parameters in patients with and without respiratory muscle weakness after trainings.Thus,we allocated the patients to two subgroups,based on their respiratory muscle strength.The respiratory muscle weakness was defined as a PImax<60 cmH2O.At baseline,there were no significant differences in these parameters,except in PImax,VT/Ti and VE(P<0.05)between patients with and without respiratory muscle weakness.There was no significant difference of the changes in these paraments between the two groups before and after IMT and EMT(P>0.05).There was a significantly difference in Ti/Ttot between the two groups before and after CRMT(P<0.05),and there were no significant differences in other indices(P>0.05).[Conclusion]1.In COPD patients,the different types of respiratory muscle threshold load training can increase the strength of diaphragm,respiratory work and neural respiratory drive,decrease the ventilation efficiency during the training.Inspiratory muscle training and concurrent inspiratory and expiratory muscle training can increase diaphragm fatigue.2.In COPD patients,there were short-term improvement in respiratory pattern and ventilation efficiency after the different types of respiratory muscle threshold load training.3.Healthy people can also obtain respiratory physiology improvement from different types of respiratory muscle threshold load training,but the rehabilitation benefit is less than COPD patients at the low level of threshold load training.4.The respiratory muscle threshold load training can benefit COPD patients with and without respiratory muscle weakness.The concurrent inspiratory and expiratory muscle training was more useful to these without respiratory muscle weakness.5.We should consider the degree of fatigue caused by different types of respiratory muscle threshold load training,avoid excessive fatigue caused by inappropriate train when working-up individualized rehabilitation program.The present study provides the respiratory physiology evidences for COPD patients undergoing different types of respiratory muscle threshold load training.We studied the immediate physiological changes during training and a short-term time after training in COPD patients and normal subjects.The long-term effects of respiratory muscle threshold load training on respiratory physiology in COPD patients are still unclear and need to be further explored by prospective randomized controlled trials... |
PDF Full Text Request