628038
research-article2016
CRE0010.1177/0269215515628038Clinical RehabilitationZeren et al.
CLINICAL REHABILITATION
Original Article
Effects of inspiratory muscle training on pulmonary function, respiratory muscle strength and functional capacity in patients with atrial fibrillation: A randomized controlled trial
Clinical Rehabilitation 1–10 © The Author(s) 2016 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0269215515628038 cre.sagepub.com
Melih Zeren1, Rengin Demir2, Zerrin Yigit2 and Hulya N Gurses1
Abstract Objective: To investigate the effects of inspiratory muscle training on pulmonary function, respiratory muscle strength and functional capacity in patients with atrial fibrillation. Design: Prospective randomized controlled single-blind study. Setting: Cardiology department of a university hospital. Subjects: A total of 38 patients with permanent atrial fibrillation were randomly allocated to either a treatment group (n = 19; age 66.2 years (8.8)) or a control group (n = 19; age 67.1 years (6.4)). Methods: The training group received inspiratory muscle training at 30% of maximal inspiratory pressure for 15 minutes twice a day, 7 days a week, for 12 weeks alongside the standard medical treatment. The control group received standard medical treatment only. Spirometry, maximal inspiratory and expiratory pressures and 6-minute walking distance was measured at the beginning and end of the study. Results: There was a significant increase in maximal inspiratory pressure (27.94 cmH2O (8.90)), maximal expiratory pressure (24.53 cmH2O (10.34)), forced vital capacity (10.29% (8.18) predicted), forced expiratory volume in one second (13.88% (13.42) predicted), forced expiratory flow 25%–75% (14.82% (12.44) predicted), peak expiratory flow (19.82% (15.62) predicted) and 6-minute walking distance (55.53 m (14.13)) in the training group (p 0.05). Conclusion: Inspiratory muscle training can improve pulmonary function, respiratory muscle strength and functional capacity in patients with atrial fibrillation. Keywords Atrial fibrillation, respiratory muscle training, maximal inspiratory pressure, pulmonary function test, 6-minute walk test Received: 4 August 2015; accepted: 30 December 2015 1Department
of Physiotherapy and Rehabilitation, Bezmialem Vakif University, Istanbul, Turkey 2Department of Cardiology, Istanbul University, Istanbul, Turkey
Corresponding author: Rengin Demir, Department of Cardiology, Cardiology Institute, Istanbul University, Keyci Hatun Mah Haseki Caddesi, Haseki, Istanbul, Turkey. Email: [email protected]
Downloaded from cre.sagepub.com at UQ Library on January 31, 2016
2
Clinical Rehabilitation
Introduction Fatigue, shortness of breath and exercise intolerance are the most common non-specific symptoms in atrial fibrillation.1 For some patients, exercise intolerance is the major symptom and up to 15%– 20% decrease can occur in exercise capacity.2 Also, it is shown that forced vital capacity, forced expiratory volume in one second and total lung capacity values are lower in patients with atrial fibrillation compared with healthy individuals.3–5 In the systematic reviews it is seen that exercise tolerance in patients with atrial fibrillation can be improved with exercise training.6,7 But, despite the disturbance in the respiratory physiology, there are no studies investigating the effects of exercise training on pulmonary function in this group of patients. Besides, in a recent systematic review it is stated that future studies examining the effects of various forms of exercise training interventions in improving clinical outcomes in these patients are needed.6 In the literature, various modes of exercise training, including inspiratory muscle training, are defined for improving cardiorespiratory fitness.8 As supported by the recent meta-analyses, it is clear that inspiratory muscle training improves pulmonary function, respiratory muscle strength and functional capacity and decreases dyspnea in patients with heart failure and chronic obstructive pulmonary disease.9–12 Since the patients with atrial fibrillation have similar common symptoms, such as dyspnea and exercise intolerance, we hypothesized that they could benefit from the inspiratory muscle training as well. So the aim of this study was to investigate the effects of inspiratory muscle training on pulmonary functions, respiratory muscle strength and functional capacity in patients with atrial fibrillation.
Methods Patients with permanent atrial fibrillation referred to the cardiopulmonary physiotherapy department from the department of cardiology, rhythm management clinics, in a university hospital between March 2013 and November 2013, were assessed for eligibility. The inclusion criteria were; being clinically stable, left ventricular ejection fraction above 40%
and New York Heart Association Class I (cardiac disease, but no symptoms and no limitation in ordinary physical activity, e.g. no shortness of breath when walking, climbing stairs, etc.) and Class II (mild symptoms (mild shortness of breath and/or angina) and slight limitation during ordinary activity).13 The exclusion criteria were; chronic obstructive lung disease, rheumatic valvular heart disease, previous heart valve surgery, recent coronary bypass surgery (three months prior to study), acute myocardial infarction, hypertrophic obstructive cardiomyopathy and having a pacemaker. The study was approved by the ethics committee of a university hospital and performed in accordance with the Declaration of Helsinki. Patients that met the criteria and that signed an informed consent were included in the study. All patients were informed about aim and scope of the study. A prospective, randomized controlled and single-blind study was performed. Patients were allocated either to a training or a control group using a numbered series of 38 prefilled envelops specifying group assignment generated by a computerbased program (H.N.G.) (Figure 1). The physiotherapist that collected the data was not aware of which patients belonged to the training group or the control group. Patients’ assessments (RD) and inspiratory muscle training (MZ) were performed by different physiotherapists. The training group received inspiratory muscle training alongside standard medical treatment for 12 weeks. The control group received standard medical treatment only. Standard medical treatment of permanent atrial fibrillation was based on the ventricular rate control and antithrombotic therapy for the purpose of preventing atrial fibrillation-related complications and thromboembolism.14 All patients were evaluated for pulmonary functions, respiratory muscle strength and functional capacity at the beginning and end of the study. Pulmonary functions were measured using a spirometer (Spiro USB; CareFusion, U.S.) according to the guideline of American Thoracic Society and European Respiratory Society.15 Forced vital capacity, forced expiratory volume in one second, forced vital capacity/forced expiratory volume in one second ratio, peak expiratory flow and forced
Downloaded from cre.sagepub.com at UQ Library on January 31, 2016
3
Zeren et al.
Figure 1. Flow diagram of the study.
expiratory flow 25%–75% were measured and also expressed as percentages of the predicted values.16 Maximal inspiratory and expiratory pressures were assessed using a respiratory pressure meter (MicroRPM; Micro Medical, UK) according to the guideline of American Thoracic Society and European Respiratory Society.17 Ten efforts were performed with rest intervals of 30–60 seconds between efforts. A maximum value of three efforts that vary by less than 5% was recorded for maximal inspiratory and expiratory pressures and also expressed as percentages of the predicted values according to Black and Hyatt.18
Functional capacity was measured with the 6-minute walk test according to the guideline of American Thoracic Society.19 The test was repeated two times and patients rested for 30 minutes between the two tests. The highest distance was recorded and also expressed as a percentage of the predicted values according to Gibbons et al.20 Threshold Inspiratory Muscle Trainer (Threshold IMT) device (Respironics, U.S.) was used for inspiratory muscle training. The training group received inspiratory muscle training at 30% of maximal inspiratory pressure for 15 minutes twice a day, 7 days a week, for 12 weeks. Once a week, patients in the training group came to the
Downloaded from cre.sagepub.com at UQ Library on January 31, 2016
4
Clinical Rehabilitation
department, had their maximal inspiratory pressure measured again and received a supervised inspiratory muscle training session. Training loads were adjusted to maintain 30% of the maximal inspiratory pressure every week. Patients were instructed to maintain diaphragmatic breathing with the device for five breaths and rest for 5–10 seconds before the next five breaths and maintain this pattern for 15 minutes, twice a day. All patients wore nose-clips during training. Patients were followed up by a phone call every day to ensure that they trained properly.
Statistical analysis Statistical analyses were performed using SPSS 20.0 statistical program (SPSS Inc., USA). Demographic and clinic characteristics of the two groups were compared with student’s t-test in normal distributed values and Mann–Whitney U-test in non-normal distributed values. The chi-square test was used for categorical variables. A repeated measures analysis of variance test was performed to compare the changes in pulmonary function, respiratory muscle strength and functional capacity between the two groups, accounting for any change in baseline values. As there are no previous studies present in the literature that investigated the effects of inspiratory muscle training in patients with atrial fibrillation, based on the effects of an aerobic exercise training program in patients with atrial fibrillation, we estimated that a sample size of 16 patients in each group would have a power of 80% to detect 66 m difference21 in the 6-minute walk distance for an α value of 0.05.
Results A total of 82 patients were assessed for eligibility; 44 patients were excluded for not meeting the inclusion criteria or for declining to participate. A total of 17 patients in the treatment group and 16 patients in the control group completed the study and results of these 33 patients were analyzed (Figure 1). Demographic and clinical characteristics of the training and control groups are shown in Table 1. There were no significant differences between the
two groups in terms of age, sex, body mass index, left ventricular ejection fraction, risk factors and smoking. According to the New York Heart Association Classification, 59% of patients in the training group and 57% of patients in the control group had mild symptoms (mild shortness of breath and/or angina) and slight limitation during ordinary activity. Baseline values of pulmonary functions and respiratory muscle strength were similar in the training and control groups. There were no restrictive pathologies in the pulmonary functions and patients did not have pulmonary complaints. A percentage of the predicted values of forced vital capacity, forced expiratory volume in one second, forced expiratory flow 25%–75%, peak expiratory flow, maximal inspiratory and expiratory pressure, forced vital capacity/forced expiratory volume in one second ratio (%), maximal inspiratory pressure (cmH20) and maximal expiratory pressure (cmH20) were significantly improved in the training group compared with baseline values, and the changes between initial and final measurements in each group were significantly different between the training and control groups (p
research-article2016
CRE0010.1177/0269215515628038Clinical RehabilitationZeren et al.
CLINICAL REHABILITATION
Original Article
Effects of inspiratory muscle training on pulmonary function, respiratory muscle strength and functional capacity in patients with atrial fibrillation: A randomized controlled trial
Clinical Rehabilitation 1–10 © The Author(s) 2016 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0269215515628038 cre.sagepub.com
Melih Zeren1, Rengin Demir2, Zerrin Yigit2 and Hulya N Gurses1
Abstract Objective: To investigate the effects of inspiratory muscle training on pulmonary function, respiratory muscle strength and functional capacity in patients with atrial fibrillation. Design: Prospective randomized controlled single-blind study. Setting: Cardiology department of a university hospital. Subjects: A total of 38 patients with permanent atrial fibrillation were randomly allocated to either a treatment group (n = 19; age 66.2 years (8.8)) or a control group (n = 19; age 67.1 years (6.4)). Methods: The training group received inspiratory muscle training at 30% of maximal inspiratory pressure for 15 minutes twice a day, 7 days a week, for 12 weeks alongside the standard medical treatment. The control group received standard medical treatment only. Spirometry, maximal inspiratory and expiratory pressures and 6-minute walking distance was measured at the beginning and end of the study. Results: There was a significant increase in maximal inspiratory pressure (27.94 cmH2O (8.90)), maximal expiratory pressure (24.53 cmH2O (10.34)), forced vital capacity (10.29% (8.18) predicted), forced expiratory volume in one second (13.88% (13.42) predicted), forced expiratory flow 25%–75% (14.82% (12.44) predicted), peak expiratory flow (19.82% (15.62) predicted) and 6-minute walking distance (55.53 m (14.13)) in the training group (p 0.05). Conclusion: Inspiratory muscle training can improve pulmonary function, respiratory muscle strength and functional capacity in patients with atrial fibrillation. Keywords Atrial fibrillation, respiratory muscle training, maximal inspiratory pressure, pulmonary function test, 6-minute walk test Received: 4 August 2015; accepted: 30 December 2015 1Department
of Physiotherapy and Rehabilitation, Bezmialem Vakif University, Istanbul, Turkey 2Department of Cardiology, Istanbul University, Istanbul, Turkey
Corresponding author: Rengin Demir, Department of Cardiology, Cardiology Institute, Istanbul University, Keyci Hatun Mah Haseki Caddesi, Haseki, Istanbul, Turkey. Email: [email protected]
Downloaded from cre.sagepub.com at UQ Library on January 31, 2016
2
Clinical Rehabilitation
Introduction Fatigue, shortness of breath and exercise intolerance are the most common non-specific symptoms in atrial fibrillation.1 For some patients, exercise intolerance is the major symptom and up to 15%– 20% decrease can occur in exercise capacity.2 Also, it is shown that forced vital capacity, forced expiratory volume in one second and total lung capacity values are lower in patients with atrial fibrillation compared with healthy individuals.3–5 In the systematic reviews it is seen that exercise tolerance in patients with atrial fibrillation can be improved with exercise training.6,7 But, despite the disturbance in the respiratory physiology, there are no studies investigating the effects of exercise training on pulmonary function in this group of patients. Besides, in a recent systematic review it is stated that future studies examining the effects of various forms of exercise training interventions in improving clinical outcomes in these patients are needed.6 In the literature, various modes of exercise training, including inspiratory muscle training, are defined for improving cardiorespiratory fitness.8 As supported by the recent meta-analyses, it is clear that inspiratory muscle training improves pulmonary function, respiratory muscle strength and functional capacity and decreases dyspnea in patients with heart failure and chronic obstructive pulmonary disease.9–12 Since the patients with atrial fibrillation have similar common symptoms, such as dyspnea and exercise intolerance, we hypothesized that they could benefit from the inspiratory muscle training as well. So the aim of this study was to investigate the effects of inspiratory muscle training on pulmonary functions, respiratory muscle strength and functional capacity in patients with atrial fibrillation.
Methods Patients with permanent atrial fibrillation referred to the cardiopulmonary physiotherapy department from the department of cardiology, rhythm management clinics, in a university hospital between March 2013 and November 2013, were assessed for eligibility. The inclusion criteria were; being clinically stable, left ventricular ejection fraction above 40%
and New York Heart Association Class I (cardiac disease, but no symptoms and no limitation in ordinary physical activity, e.g. no shortness of breath when walking, climbing stairs, etc.) and Class II (mild symptoms (mild shortness of breath and/or angina) and slight limitation during ordinary activity).13 The exclusion criteria were; chronic obstructive lung disease, rheumatic valvular heart disease, previous heart valve surgery, recent coronary bypass surgery (three months prior to study), acute myocardial infarction, hypertrophic obstructive cardiomyopathy and having a pacemaker. The study was approved by the ethics committee of a university hospital and performed in accordance with the Declaration of Helsinki. Patients that met the criteria and that signed an informed consent were included in the study. All patients were informed about aim and scope of the study. A prospective, randomized controlled and single-blind study was performed. Patients were allocated either to a training or a control group using a numbered series of 38 prefilled envelops specifying group assignment generated by a computerbased program (H.N.G.) (Figure 1). The physiotherapist that collected the data was not aware of which patients belonged to the training group or the control group. Patients’ assessments (RD) and inspiratory muscle training (MZ) were performed by different physiotherapists. The training group received inspiratory muscle training alongside standard medical treatment for 12 weeks. The control group received standard medical treatment only. Standard medical treatment of permanent atrial fibrillation was based on the ventricular rate control and antithrombotic therapy for the purpose of preventing atrial fibrillation-related complications and thromboembolism.14 All patients were evaluated for pulmonary functions, respiratory muscle strength and functional capacity at the beginning and end of the study. Pulmonary functions were measured using a spirometer (Spiro USB; CareFusion, U.S.) according to the guideline of American Thoracic Society and European Respiratory Society.15 Forced vital capacity, forced expiratory volume in one second, forced vital capacity/forced expiratory volume in one second ratio, peak expiratory flow and forced
Downloaded from cre.sagepub.com at UQ Library on January 31, 2016
3
Zeren et al.
Figure 1. Flow diagram of the study.
expiratory flow 25%–75% were measured and also expressed as percentages of the predicted values.16 Maximal inspiratory and expiratory pressures were assessed using a respiratory pressure meter (MicroRPM; Micro Medical, UK) according to the guideline of American Thoracic Society and European Respiratory Society.17 Ten efforts were performed with rest intervals of 30–60 seconds between efforts. A maximum value of three efforts that vary by less than 5% was recorded for maximal inspiratory and expiratory pressures and also expressed as percentages of the predicted values according to Black and Hyatt.18
Functional capacity was measured with the 6-minute walk test according to the guideline of American Thoracic Society.19 The test was repeated two times and patients rested for 30 minutes between the two tests. The highest distance was recorded and also expressed as a percentage of the predicted values according to Gibbons et al.20 Threshold Inspiratory Muscle Trainer (Threshold IMT) device (Respironics, U.S.) was used for inspiratory muscle training. The training group received inspiratory muscle training at 30% of maximal inspiratory pressure for 15 minutes twice a day, 7 days a week, for 12 weeks. Once a week, patients in the training group came to the
Downloaded from cre.sagepub.com at UQ Library on January 31, 2016
4
Clinical Rehabilitation
department, had their maximal inspiratory pressure measured again and received a supervised inspiratory muscle training session. Training loads were adjusted to maintain 30% of the maximal inspiratory pressure every week. Patients were instructed to maintain diaphragmatic breathing with the device for five breaths and rest for 5–10 seconds before the next five breaths and maintain this pattern for 15 minutes, twice a day. All patients wore nose-clips during training. Patients were followed up by a phone call every day to ensure that they trained properly.
Statistical analysis Statistical analyses were performed using SPSS 20.0 statistical program (SPSS Inc., USA). Demographic and clinic characteristics of the two groups were compared with student’s t-test in normal distributed values and Mann–Whitney U-test in non-normal distributed values. The chi-square test was used for categorical variables. A repeated measures analysis of variance test was performed to compare the changes in pulmonary function, respiratory muscle strength and functional capacity between the two groups, accounting for any change in baseline values. As there are no previous studies present in the literature that investigated the effects of inspiratory muscle training in patients with atrial fibrillation, based on the effects of an aerobic exercise training program in patients with atrial fibrillation, we estimated that a sample size of 16 patients in each group would have a power of 80% to detect 66 m difference21 in the 6-minute walk distance for an α value of 0.05.
Results A total of 82 patients were assessed for eligibility; 44 patients were excluded for not meeting the inclusion criteria or for declining to participate. A total of 17 patients in the treatment group and 16 patients in the control group completed the study and results of these 33 patients were analyzed (Figure 1). Demographic and clinical characteristics of the training and control groups are shown in Table 1. There were no significant differences between the
two groups in terms of age, sex, body mass index, left ventricular ejection fraction, risk factors and smoking. According to the New York Heart Association Classification, 59% of patients in the training group and 57% of patients in the control group had mild symptoms (mild shortness of breath and/or angina) and slight limitation during ordinary activity. Baseline values of pulmonary functions and respiratory muscle strength were similar in the training and control groups. There were no restrictive pathologies in the pulmonary functions and patients did not have pulmonary complaints. A percentage of the predicted values of forced vital capacity, forced expiratory volume in one second, forced expiratory flow 25%–75%, peak expiratory flow, maximal inspiratory and expiratory pressure, forced vital capacity/forced expiratory volume in one second ratio (%), maximal inspiratory pressure (cmH20) and maximal expiratory pressure (cmH20) were significantly improved in the training group compared with baseline values, and the changes between initial and final measurements in each group were significantly different between the training and control groups (p
