Effects Of Combined Cycle Ergometer And Inspiratory Muscle Training In Patients With Stable Chronic Obstructive Pulmonary Disease

[Background]Chronic obstructive pulmonary disease (COPD), the fourth leading cause of death, is one of the major cause of chronic morbidity, mortality and disability throughout the world. The main therapy for COPD is pharmacotherapy. Within the last decade, integrated care has risen to be regarded as an optimal approach towards managing chronic respiratory disease, and pulmonary rehabilitation has established itself as an important component of this model. The science and effectiveness of pulmonary rehabilitation in COPD have been demonstrated by several large-scale randomized controlled clinical trials. In 2013, American thoracic society(ATS) and European respiratory society(ERS) had jointly published an updated version of guidelines of pulmonary rehabilitation and adopted the following definition of pulmonary rehabilitation:Pulmonary rehabilitation is an integrated intervention based on a thorough patient assessment followed by patient individualized therapies that include, but are not limited to, exercise training, education, and behavior change, designed to improve the physical and psychological condition of people with chronic respiratory disease and to promote the long-term adherence to health-enhancing behaviors. However, the pulmonary rehabilitation in China still at a preliminary stage, application and research of pulmonary rehabilitation has not yet to be conduct in most parts of our country. Therefore, to strengthen extension and research of pulmonary rehabilitation in China may be of great interest.Although individualized treatment has been gradually recommended in pulmonary rehabilitation, several issues of prescription which are associated with clinical practice still remain unclear, such as forms, program and intensity of pulmonary rehabilitation. There are several forms of pulmonary rehabilitation and dissimilar forms can produce different therapeutic effects. Recently, most forms of pulmonary rehabilitation have been performed in lower limb training. However, the exercise intensity is limited by the severities of dyspnea during exercises which result from the pathological mechanism of COPD. Increased attention has focused on the benefits of inspiratory muscle training, which can increases inspiratory muscle strength and endurance meanwhile improves dyspnea during exercises. However, an additional benefit on pulmonary rehabilitation of inspiratory muscle training given as an adjunct to lower limb exercise training still remains unclear.The effects of pulmonary rehabilitation need long-term measured by symptom, exercise performance and quality of life. COPD is a multisystem disease. There are some defects in each evaluation method, thus it is important for pulmonary rehabilitation to comprehensively evaluate the effects with multiple indicators. This research comprehensively evaluated pulmonary rehabilitation by pulmonary function, exercise capacity, dyspnea, quality of life, depression and anxiety, nutritional status.[Objective]The present study aims to comprehensively evaluate the effects of combined cycle ergometer and inspiratory muscle training in patients with stable COPD and provide evidences for optimizing program of pulmonary rehabilitation. Moreover, we would like to determine the effects of pulmonary rehabilitation in COPD patients with different severity and provide evidences for making individualized treatment strategies.[Methods]81 patients with stable COPD who were enrolled from the department of respiratory medicine, Zhujiang Hospital, Southern Medical University and met the inclusion criteria and exclusion criteria, were recruited for this study. The basic information and clinical data of all subjects, such as static pulmonary function, exercise capacity, dyspnea, quality of life, depression and anxiety, nutritional status and BODE index were recorded. Patients were randomized into three groups by a table of random numbers, i.e:control group, cycle ergometer group and combined group. Subjects in control group accepted no intervention. Subjects in cycle ergometer group performed lower limb training for 8 weeks, while Subjects in combined group performed lower limb with inspiratory muscle training for 8 weeks in hospital out-patient clinics. The clinical data were recorded after training once again. The statistical analyses were performed by using SPSS 19.0 software. Results were presented as the mean ± standard deviation and proportional data were presented as number (percentages). Statistical significance of differences in 3 groups were estimated with one-way analysis or covariance analysis for multiple comparisons, between two groups and within a group were determined by using independent-sample t test and paired-sample t test, respectively. Enumeration data were tested by chi-square. A p-value of less than 0.05 was considered statistically significant.[Result]1. Basic characteristics of subjects73 patients completed the rehabilitation programme, of 81 stable COPD patients who enrolled in this study.73 stable COPD patients were randomly assigned into control group (24 cases), cycle ergometer group(24 cases), and combined group(25 cases). Baseline characteristics of the three groups were similar in all demographic and clinical data, such as static pulmonary function, exercise capacity, dyspnea, quality of life, depression and anxiety, nutritional status and respiratory muscle strength.2. Effects of pulmonary rehabilitation on static pulmonary functionThe parameters of lung function including FVC, FVC%pred, FEV1, FEV1%pred, FEVi/FVC, MVV were not significantly different in all group(P>0.05).3. Effects of pulmonary rehabilitation on exercise capacityThe maximum oxygen consumption of predicted (VO2max%pred) at baseline (64.69±18.57, t=-8.760, P=0.001) and anaerobic threshold of predicted (AT%pred) at baseline (52.34±14.71, t=-3.244,P=0.002) were significantly lower than normal values.No significant changes of the exercise capacity indices were found in control group after training. A significant increase was found in 6 minute walk distance, VO2max (maximum oxygen consumption), VO2max%pred, VO2max/kg, anaerobic threshold (AT) and AT%pred after training (P<0.05) both in cycle ergometer group and combined group.Both cycle ergometer group and combined group demonstrated a significant increase in 6 minute walk distance, V02max, VO2max%pred, VO2max/Kg, AT and AT%pred compared with the control group(P<0.05). However, there were no differences between cycle ergometer group and combined group (P>0.05).4. Effect of pulmonary rehabilitation on respiratory muscle strengthBoth cycle ergometer group and combined group demonstrated a significant increase in maximum expiratory pressure(PEmax) compared with control group (P<0.05). However, there were no differences between cycle ergometer group and combined group (P>0.05). There are significant differences in maximum inspiratory pressure(PImax) among three groups, and PImax of combined group was the highest while PImax of control group was the lowest.5. Effects of pulmonary rehabilitation on dyspnea, quality of life, depression and anxietyBoth cycle ergometer group and combined group demonstrated a significant increase in dyspnea, quality of life, depression and anxiety compared with the control group (P<0.05). There were no significant changes in BODE index and no significant differences in other index between cycle ergometer group and combined group (P>0.05).6. Effect of pulmonary rehabilitation on nutritional statusThe BMI (21.62±3.18, t=8.393, P=0.001) of patients measured by bio-impedance analysis at baseline was significantly higher than normal values. FFMI (16.40±2.34,t=1.448, P=0.152) at baseline was similar with normal values. The patients with lower BMI and FFMI is 10 cases (13.70%,10/73) and 16 cases (21.92%,16/73), respectively.There were no significant changes in BMI among three groups (P>0.05). Both cycle ergometer group and combined group demonstrated a significant improvement in FFMI with the control group (P<0.05). However, there were no differences between cycle ergometer group and combined group in FFMI (P>0.05).7. Effects of pulmonary rehabilitation in COPD with respiratory muscle weaknessRegarding the subgroup analysis between subjects with and without respiratory muscle weakness in training patients, there were no significant differences in static pulmonary function, exercise capacity, dyspnea, quality of life, depression and anxiety and nutritional status between two subgroups (P>0.05).Regarding the subgroup analysis between subjects with and without respiratory muscle weakness in combined group, there were no significant differences in static pulmonary function, exercise capacity, dyspnea, quality of life, depression and anxiety and nutritional status between two subgroups (P>0.05).8. Effects of pulmonary rehabilitation in COPD with malnutritionRegarding the subgroup analysis between subjects with normal nutrition and with malnutrition in training patients, there were no significant differences in static pulmonary function, exercise capacity, dyspnea, quality of life, depression and anxiety, nutritional status and respiratory muscle strength between two subgroups (P>0.05).[Conclusion]The present study suggested that stable COPD patients had significant improvements in exercise capacity, dyspnea, quality of life, depression and anxiety, nutritional status and respiratory muscle strength after pulmonary rehabilitation. Combined cycle ergometer and inspiratory muscle training had an additional benefit on inspiratory muscle strength compared with cycle ergometer training, but not on other indicators. Combined training had not an additional benefit on COPD patients with inspiratory muscle weakness. The COPD patients had significant improvements in nutritional status after pulmonary rehabilitation, however, nutritional status had slight impact on pulmonary rehabilitation.