P U L M O N A RY R E H A B I L I TAT I O N
Inspiratory Muscle Training in Pulmonary Arterial Hypertension Melda Saglam, PT, PhD; Hulya Arikan, PT, PhD; Naciye Vardar-Yagli, PT, PhD; Ebru Calik-Kutukcu, PT, MSc; Deniz Inal-Ince, PT, PhD; Sema Savci, PT, PhD; Ali Akdogan, MD; Mehmet Yokusoglu, MD; Ergun Baris Kaya, MD; Lale Tokgozoglu, MD
■ PURPOSE: The purpose of this study was to investigate the effects of inspiratory muscle training (IMT) on functional capacity, respiratory muscle strength, pulmonary function, quality of life, and fatigue and dyspnea perception in patients with pulmonary arterial hypertension (PAH). ■ METHODS: Twenty-nine clinically stable PAH patients were included in this study. These patients were randomly assigned to a 6-week IMT program (14 patients) or to a sham IMT protocol (15 patients). Before and after the treatment, pulmonary function, respiratory muscle strength, functional capacity, dyspnea and fatigue perception, and quality of life were evaluated. ■ RESULTS: There were significant increases in maximal inspiratory and expiratory pressure, forced expiratory volume in 1 second (% predicted) and 6-minute walk distance in the IMT group compared with the control group (P < .05). There were significant decreases in the Fatigue Severity Scale score, Modified Medical Research Council dyspnea scores, and Nottingham Health Profile emotional reactions subscale in the IMT group compared with the control group (P < .05). ■ CONCLUSIONS: Inspiratory muscle training promotes significant improvements in respiratory muscle strength and functional capacity, thus resulting in a reduction of dyspnea during activities of daily living and less fatigue in PAH patients. Inspiratory muscle training is a clinically practical treatment for PAH without any complications.
K E Y
W O R D S
functional capacity inspiratory muscle training pulmonary hypertension quality of life Author Affiliations: Faculty of Health Sciences, Department of Physiotherapy and Rehabilitation (Drs Saglam, Arikan, Vardar-Yagli, and Inal-Ince, Ms CalikKutukcu), Faculty of Medicine, Department of Internal Medicine, Unit of Rheumatology (Dr Akdogan), and Faculty of Medicine, Department of Cardiology (Drs Kaya and Tokgozoglu), Hacettepe University, Ankara, Turkey; School of Physiotherapy and Rehabilitation, Dokuz Eylul University, Izmir, Turkey (Dr Savci); Department of Cardiology, Gülhane Military Medicine Academy, Ankara, Turkey (former) (Dr Yokusoglu). The authors declare no conflicts of interest. Correspondence: Melda Saglam, PT, PhD, Faculty of Health Sciences, Department of Physiotherapy and Rehabilitation, Hacettepe University, Samanpazari, Ankara 06100, Turkey (msaglam@ hacettepe.edu.tr). DOI: 10.1097/HCR.0000000000000117
Pulmonary arterial hypertension (PAH) is a pathophysiological state defined by an increase in mean pulmonary arterial pressure ≥25 mm Hg at rest and confirmed by right heart catheterization.1,2 Pulmonary arterial hypertension has various etiologies and can be
either idiopathic or associated with other disorders, such as connective tissue disease, congenital heart disease, or autoimmune diseases. Pulmonary arterial hypertension is characterized by an excessive increase in pulmonary vascular resistance, which causes an
198 / Journal of Cardiopulmonary Rehabilitation and Prevention 2015;35:198-206
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JCRP-D-14-00068_LR 198
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increase in right ventricular afterload, resulting in right heart failure and subsequent death.3 These hemodynamic findings impair exercise capacity in patients with PAH. Symptoms of PAH include syncope, dyspnea, and excessive fatigue and limit daily life and physical function.4,5 Recent studies have found that patients with PAH have inspiratory muscle weakness, measured using both volitional and nonvolitional tests, which possibly results in further increases in fatigue and dyspnea during exercise.6,7 These studies have demonstrated that patients with PAH experience hyperventilation, not only during exercise but also at rest. This continuous inspiratory muscle activity increases the demand on muscles and reduces the force-generation capacity, ultimately leading to respiratory muscle weakness.6 Pulmonary arterial hypertension patients decrease their physical activity level to avoid dyspnea during exertion, which leads to physical deconditioning.8 This profound physical deconditioning could also contribute to inspiratory muscle weakness in persons with PAH, further contributing to reduced exercise capacity and quality of life (QoL). We hypothesized that inspiratory muscle training (IMT) might play a role in increasing respiratory muscle strength and lead to better physical function in PAH. In other chronic conditions, such as chronic obstructive pulmonary disease (COPD) and left heart failure, IMT has been shown to increase respiratory muscle strength and endurance, improve functional capacity and QoL, and reduce dyspnea perception.9,10 Although respiratory muscle dysfunction has been documented in patients with PAH, the effect of respiratory muscle training is unknown. Therefore, the purpose of this prospective, randomized controlled study was to investigate the effects of IMT on pulmonary function, respiratory muscle strength, functional capacity, dyspnea and fatigue perception, and QoL in patients with PAH.
METHODS Twenty-nine patients with PAH were included in this study. The inclusion criteria were clinically stable patients, World Health Organization (WHO) functional classes11 II and III, with no change in diseasetargeted medications over the preceding 3 months. The exclusion criteria were severe obstructive and restrictive lung diseases, severe ischemic heart disease, left heart failure, cor pulmonale, cognitive disorders, recent (6 months prior to study) viral infections, and orthopedic problems. The study was approved by the ethics committee of the university and performed in accordance with the Declaration of Helsinki. www.jcrpjournal.com
Written informed consent was obtained from all patients before participating in the study. This was a prospective, randomized controlled study. Prior to randomization, all patients’ clinical evaluation and echocardiography measurements were performed by a cardiologist and a rheumatologist. All patients were receiving optimal medical treatment at the time they entered the study. Patients were randomly allocated to either a treatment group (15 patients) or a control group (14 patients), using a program to generate random numbers. Neither the patients nor the clinicians assessing respiratory pressures were aware of the group to which patients had been allocated. The treatment group received IMT, while the control group received sham IMT. Patients were trained using an inspiratory threshold-loading device (Respironics, Pittsburgh, PA). The intervention group received IMT at 30% of maximal inspiratory pressure (MIP). The MIP was measured every week, and the resistance was adjusted to maintain 30% of MIP. The control group received sham IMT at a fixed workload of 10% of MIP. Both groups trained for 30 minutes per day, 7 days per week, for 6 weeks. Following the end of the intervention, patients were observed for 2 days in the laboratory. Before and after the IMT, pulmonary function, respiratory muscle strength, functional capacity, dyspnea and fatigue perception, and QoL were evaluated. Lung function testing was performed using portable spirometry (Spirobank Medical International Research, Rome, Italy) according to the American Thoracic Society and the European Respiratory Society guidelines. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and peak expiratory flow were measured and expressed as the percentages of the predicted values.12 The MIP and maximal expiratory pressure (MEP) were assessed using a mouth pressure device (MicroRPM, Micromedical, Kent, United Kingdom) with a rigid flanged mouthpiece. The MIP was measured near a residual volume after a maximal expiration, and the MEP was measured near total lung capacity after a maximal inspiration. The MIP and MEP values were calculated from the maximum effort sustained for 1 second. Tests were repeated until no further improvements were obtained and there was less than a 10% difference between the two best values.13,14 The MIP and MEP percentages were calculated as a percentage of their predicted values.15 A threshold of 80 cmH2O was used to define inspiratory muscle weakness.15 Functional capacity was evaluated using a 6-minute walk test (6MWT). The subjects were instructed to walk for 6 minutes in an enclosed 30-m long corridor.
Inspiratory Muscle Training in Pulmonary Arterial Hypertension / 199
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JCRP-D-14-00068_LR 199
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No encouragement was given to the patients, and patients were allowed to stop and rest during the test but were instructed to go on walking as far as possible.16 Heart rate was monitored and oxygen saturation was measured during the test. Breathlessness and fatigue perception were determined using the Modified Borg Dyspnea Scale before and after the 6MWT.17 All PAH patients had previously performed the 6MWT several times so the test was performed only once. The Modified Medical Research Council (MMRC) dyspnea scale was used to evaluate dyspnea severity during activity. Levels of dyspnea are graded from 0 (absence of dyspnea during strenuous exercise) to 4 (too breathless to leave the house or breathless while dressing or undressing).18 Fatigue was evaluated using the Fatigue Severity Scale (FSS),19 which is a self- administered questionnaire consisting of 9 items. Patients were asked to rate their level of agreement with each item scored 0 to 7 (0 = strong disagreement; 7 = strong agreement). A score of 36 and above (out of a maximum of 63) indicates the presence of significant fatigue.19 Quality of life was assessed using the Nottingham Health Profile (NHP). It is a self-administered questionnaire that includes 38 statements that describe limitations of activity or aspects of distress in 6 dimensions—physical mobility, pain, sleep, energy, social isolation, and emotional reactions. Patients indicated by using a yes or no answer regarding problems they were experiencing when completing the questionnaire. A score ranging from 0 to 100 was calculated for each dimension. Higher scores indicate greater limitations in activity or social or emotional problems.20,21
Statistical Analysis Data were analyzed using the statistical software package SPSS version 16.0 (SPSS, Inc, Chicago, IL) and tested using the Kolmogorov-Smirnov calculation for normality. Statistical tests were 2-tailed and P < .05 was considered statistically significant. Analysis of continuous variables within and between the groups was completed using the Student t test, and analysis between IMT and control groups was performed using the chi-square test (nominal data) and the Mann-Whitney U test (ordinal data). As this was the first study on this topic in PAH, effect sizes were not derived based on previous subjects who participated in similar training programs. However, to calculate clinically important differences between groups using MIP values as the primary outcome measure, with 80% statistical power and an alpha of 0.05, an increase in MIP of a median of 12 cmH2O was found to be significant.
RESULTS Thirty-one of the 55 total patients who were screened met the inclusion criteria. All 31 of these patients underwent baseline measurements. One patient from the control group withdrew and 1 patient in the control group did not receive the treatment due to the onset of a pulmonary aneurysm. Therefore, 14 patients in the IMT group and 15 patients in the control group were included in the analyses. Patient demographic characteristics, diagnoses, functional class, and medical therapy are presented in Table 1. There were no significant differences in demographic and clinical variables between the groups. Both groups were heterogeneous and included patients with PAH and other PAH-associated
T a b l e 1 • Baseline Patient Characteristicsa All Patients IMT Group (n = 31) (n = 14)
Control Group (n = 17)
49.7 ± 12.4
46.8 ± 15.6
52.2 ± 8.8
25 (80.6)
11 (78.6)
14 (82.4)
BMI, kg/m
26.7 ± 6.1
25.6 ± 3.7
27.6 ± 7.5
Duration of disease, y
5.6 ± 4.6
5.7 ± 4.6
5.4 ± 4.7
67.3 ± 31.8
77.1 ± 34.7
59.5 ± 28.1
Age, y Female, n (%) 2
Mean PAP, mm Hg
WHO/NYHA functional class, n (%) Class II
16 (51.6)
7 (50)
9 (52.9)
Class III
15 (48.4)
7 (50)
8 (47.1)
Idiopathic PAH
8 (25.8)
3 (21.4)
5 (29.4)
PAH etiology, n (%) Scleroderma
12 (38.7)
5 (35.7)
7 (41.2)
Rheumatoid arthritis
4 (12.9)
2 (14.3)
2 (11.8)
Congenital heart diseases
7 (22.6)
4 (28.6)
3 (17.6)
Bosentan
10 (32.3)
5 (36)
5 (29.4)
Ilioprost
7 (22.6)
2 (14.2)
5 (29.4)
Drug therapy, n (%)
3 (9.7)
2 (14.2)
1 (5.8)
Anticoagulant therapy
Sildenafil
17 (54.8)
10 (71.4)
7 (41.2)
Nifedipine
5 (16.1)
3 (21.4)
2 (11.7)
Abbreviations: BMI, body mass index; IMT, inspiratory muscle training; NYHA, New York Heart Association; PAH, pulmonary artery hypertension; PAP, pulmonary artery pressure; WHO, World Health Organization. a All continuous data presented as mean ± SD. No significant differences between groups for all variables.
200 / Journal of Cardiopulmonary Rehabilitation and Prevention 2015;35:198-206
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Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
JCRP-D-14-00068_LR 200
10/04/15 7:32 PM
weeks of training, MIP, MIP percentage predicted, MEP, and MEP percentage predicted were significantly improved in the IMT group but not in the control group. After the intervention, only 2 (14%) patients in the treatment group had inspiratory muscle weakness, whereas 10 (60%) patients in the control group were still experiencing inspiratory muscle weakness. Inspiratory muscle training resulted in a mean improvement of 26.14 ± 12.15 cmH2O in MIP in the intervention group, whereas the mean change in MIP was a nonsignificant 5.87 ± 12.64 cmH2O for the control group (Figure 1A). There was also a significant difference between the change in MEP between the intervention and control groups (10.00 ± 8.28 cmH2O and 2.80 ± 9.81 cmH2O, respectively) (Figure 1B; P < .05).
conditions, such as congenital heart disease, scleroderma, and rheumatoid arthritis. The IMT intervention was well tolerated by all of the patients, and there were no syncope or presyncope episodes, arrhythmias, or respiratory complications. No significant changes were detected in vital signs during and recovery from the treatment. Only 1 patient suffered from muscle soreness in the first treatment session, although he or she did not stop the training. Patients demonstrated good adherence to the IMT program, and there were no training dropouts.
Pulmonary Function Table 2 shows the results of lung function testing. In the intervention group, percentages of predicted for FEV1 and FVC increased significantly after IMT training. There were no significant changes in lung function testing variables for the control group after the sham IMT. A significant difference in FEV1 percentage predicted was found between the 2 groups. The baseline FEV1 percentage predicted correlated with MIP (r = 0.480; P = .007) and 6MWT distance (r = 0.567; P < .001) in all PAH patients.
Functional Capacity Table 3 shows the data obtained during the 6MWT before and after the training. No statistically significant differences were observed in heart rate, oxygen saturation, lower limb muscle fatigue, and dyspnea perception after training (Table 3). However, a statistically significant improvement was observed in the distance walked and percentage of predicted walk distance. There was a 50-m increase in the mean distance walked in the IMT group. There were no significant changes in the 6MWT distance or the percentage of predicted distance in the control group.
Respiratory Muscle Strength Ten patients (71%) in the IMT group and 11 patients (65%) in the control group had inspiratory muscle weakness at baseline (MIP
Inspiratory Muscle Training in Pulmonary Arterial Hypertension Melda Saglam, PT, PhD; Hulya Arikan, PT, PhD; Naciye Vardar-Yagli, PT, PhD; Ebru Calik-Kutukcu, PT, MSc; Deniz Inal-Ince, PT, PhD; Sema Savci, PT, PhD; Ali Akdogan, MD; Mehmet Yokusoglu, MD; Ergun Baris Kaya, MD; Lale Tokgozoglu, MD
■ PURPOSE: The purpose of this study was to investigate the effects of inspiratory muscle training (IMT) on functional capacity, respiratory muscle strength, pulmonary function, quality of life, and fatigue and dyspnea perception in patients with pulmonary arterial hypertension (PAH). ■ METHODS: Twenty-nine clinically stable PAH patients were included in this study. These patients were randomly assigned to a 6-week IMT program (14 patients) or to a sham IMT protocol (15 patients). Before and after the treatment, pulmonary function, respiratory muscle strength, functional capacity, dyspnea and fatigue perception, and quality of life were evaluated. ■ RESULTS: There were significant increases in maximal inspiratory and expiratory pressure, forced expiratory volume in 1 second (% predicted) and 6-minute walk distance in the IMT group compared with the control group (P < .05). There were significant decreases in the Fatigue Severity Scale score, Modified Medical Research Council dyspnea scores, and Nottingham Health Profile emotional reactions subscale in the IMT group compared with the control group (P < .05). ■ CONCLUSIONS: Inspiratory muscle training promotes significant improvements in respiratory muscle strength and functional capacity, thus resulting in a reduction of dyspnea during activities of daily living and less fatigue in PAH patients. Inspiratory muscle training is a clinically practical treatment for PAH without any complications.
K E Y
W O R D S
functional capacity inspiratory muscle training pulmonary hypertension quality of life Author Affiliations: Faculty of Health Sciences, Department of Physiotherapy and Rehabilitation (Drs Saglam, Arikan, Vardar-Yagli, and Inal-Ince, Ms CalikKutukcu), Faculty of Medicine, Department of Internal Medicine, Unit of Rheumatology (Dr Akdogan), and Faculty of Medicine, Department of Cardiology (Drs Kaya and Tokgozoglu), Hacettepe University, Ankara, Turkey; School of Physiotherapy and Rehabilitation, Dokuz Eylul University, Izmir, Turkey (Dr Savci); Department of Cardiology, Gülhane Military Medicine Academy, Ankara, Turkey (former) (Dr Yokusoglu). The authors declare no conflicts of interest. Correspondence: Melda Saglam, PT, PhD, Faculty of Health Sciences, Department of Physiotherapy and Rehabilitation, Hacettepe University, Samanpazari, Ankara 06100, Turkey (msaglam@ hacettepe.edu.tr). DOI: 10.1097/HCR.0000000000000117
Pulmonary arterial hypertension (PAH) is a pathophysiological state defined by an increase in mean pulmonary arterial pressure ≥25 mm Hg at rest and confirmed by right heart catheterization.1,2 Pulmonary arterial hypertension has various etiologies and can be
either idiopathic or associated with other disorders, such as connective tissue disease, congenital heart disease, or autoimmune diseases. Pulmonary arterial hypertension is characterized by an excessive increase in pulmonary vascular resistance, which causes an
198 / Journal of Cardiopulmonary Rehabilitation and Prevention 2015;35:198-206
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Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
JCRP-D-14-00068_LR 198
10/04/15 7:32 PM
increase in right ventricular afterload, resulting in right heart failure and subsequent death.3 These hemodynamic findings impair exercise capacity in patients with PAH. Symptoms of PAH include syncope, dyspnea, and excessive fatigue and limit daily life and physical function.4,5 Recent studies have found that patients with PAH have inspiratory muscle weakness, measured using both volitional and nonvolitional tests, which possibly results in further increases in fatigue and dyspnea during exercise.6,7 These studies have demonstrated that patients with PAH experience hyperventilation, not only during exercise but also at rest. This continuous inspiratory muscle activity increases the demand on muscles and reduces the force-generation capacity, ultimately leading to respiratory muscle weakness.6 Pulmonary arterial hypertension patients decrease their physical activity level to avoid dyspnea during exertion, which leads to physical deconditioning.8 This profound physical deconditioning could also contribute to inspiratory muscle weakness in persons with PAH, further contributing to reduced exercise capacity and quality of life (QoL). We hypothesized that inspiratory muscle training (IMT) might play a role in increasing respiratory muscle strength and lead to better physical function in PAH. In other chronic conditions, such as chronic obstructive pulmonary disease (COPD) and left heart failure, IMT has been shown to increase respiratory muscle strength and endurance, improve functional capacity and QoL, and reduce dyspnea perception.9,10 Although respiratory muscle dysfunction has been documented in patients with PAH, the effect of respiratory muscle training is unknown. Therefore, the purpose of this prospective, randomized controlled study was to investigate the effects of IMT on pulmonary function, respiratory muscle strength, functional capacity, dyspnea and fatigue perception, and QoL in patients with PAH.
METHODS Twenty-nine patients with PAH were included in this study. The inclusion criteria were clinically stable patients, World Health Organization (WHO) functional classes11 II and III, with no change in diseasetargeted medications over the preceding 3 months. The exclusion criteria were severe obstructive and restrictive lung diseases, severe ischemic heart disease, left heart failure, cor pulmonale, cognitive disorders, recent (6 months prior to study) viral infections, and orthopedic problems. The study was approved by the ethics committee of the university and performed in accordance with the Declaration of Helsinki. www.jcrpjournal.com
Written informed consent was obtained from all patients before participating in the study. This was a prospective, randomized controlled study. Prior to randomization, all patients’ clinical evaluation and echocardiography measurements were performed by a cardiologist and a rheumatologist. All patients were receiving optimal medical treatment at the time they entered the study. Patients were randomly allocated to either a treatment group (15 patients) or a control group (14 patients), using a program to generate random numbers. Neither the patients nor the clinicians assessing respiratory pressures were aware of the group to which patients had been allocated. The treatment group received IMT, while the control group received sham IMT. Patients were trained using an inspiratory threshold-loading device (Respironics, Pittsburgh, PA). The intervention group received IMT at 30% of maximal inspiratory pressure (MIP). The MIP was measured every week, and the resistance was adjusted to maintain 30% of MIP. The control group received sham IMT at a fixed workload of 10% of MIP. Both groups trained for 30 minutes per day, 7 days per week, for 6 weeks. Following the end of the intervention, patients were observed for 2 days in the laboratory. Before and after the IMT, pulmonary function, respiratory muscle strength, functional capacity, dyspnea and fatigue perception, and QoL were evaluated. Lung function testing was performed using portable spirometry (Spirobank Medical International Research, Rome, Italy) according to the American Thoracic Society and the European Respiratory Society guidelines. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and peak expiratory flow were measured and expressed as the percentages of the predicted values.12 The MIP and maximal expiratory pressure (MEP) were assessed using a mouth pressure device (MicroRPM, Micromedical, Kent, United Kingdom) with a rigid flanged mouthpiece. The MIP was measured near a residual volume after a maximal expiration, and the MEP was measured near total lung capacity after a maximal inspiration. The MIP and MEP values were calculated from the maximum effort sustained for 1 second. Tests were repeated until no further improvements were obtained and there was less than a 10% difference between the two best values.13,14 The MIP and MEP percentages were calculated as a percentage of their predicted values.15 A threshold of 80 cmH2O was used to define inspiratory muscle weakness.15 Functional capacity was evaluated using a 6-minute walk test (6MWT). The subjects were instructed to walk for 6 minutes in an enclosed 30-m long corridor.
Inspiratory Muscle Training in Pulmonary Arterial Hypertension / 199
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JCRP-D-14-00068_LR 199
10/04/15 7:32 PM
No encouragement was given to the patients, and patients were allowed to stop and rest during the test but were instructed to go on walking as far as possible.16 Heart rate was monitored and oxygen saturation was measured during the test. Breathlessness and fatigue perception were determined using the Modified Borg Dyspnea Scale before and after the 6MWT.17 All PAH patients had previously performed the 6MWT several times so the test was performed only once. The Modified Medical Research Council (MMRC) dyspnea scale was used to evaluate dyspnea severity during activity. Levels of dyspnea are graded from 0 (absence of dyspnea during strenuous exercise) to 4 (too breathless to leave the house or breathless while dressing or undressing).18 Fatigue was evaluated using the Fatigue Severity Scale (FSS),19 which is a self- administered questionnaire consisting of 9 items. Patients were asked to rate their level of agreement with each item scored 0 to 7 (0 = strong disagreement; 7 = strong agreement). A score of 36 and above (out of a maximum of 63) indicates the presence of significant fatigue.19 Quality of life was assessed using the Nottingham Health Profile (NHP). It is a self-administered questionnaire that includes 38 statements that describe limitations of activity or aspects of distress in 6 dimensions—physical mobility, pain, sleep, energy, social isolation, and emotional reactions. Patients indicated by using a yes or no answer regarding problems they were experiencing when completing the questionnaire. A score ranging from 0 to 100 was calculated for each dimension. Higher scores indicate greater limitations in activity or social or emotional problems.20,21
Statistical Analysis Data were analyzed using the statistical software package SPSS version 16.0 (SPSS, Inc, Chicago, IL) and tested using the Kolmogorov-Smirnov calculation for normality. Statistical tests were 2-tailed and P < .05 was considered statistically significant. Analysis of continuous variables within and between the groups was completed using the Student t test, and analysis between IMT and control groups was performed using the chi-square test (nominal data) and the Mann-Whitney U test (ordinal data). As this was the first study on this topic in PAH, effect sizes were not derived based on previous subjects who participated in similar training programs. However, to calculate clinically important differences between groups using MIP values as the primary outcome measure, with 80% statistical power and an alpha of 0.05, an increase in MIP of a median of 12 cmH2O was found to be significant.
RESULTS Thirty-one of the 55 total patients who were screened met the inclusion criteria. All 31 of these patients underwent baseline measurements. One patient from the control group withdrew and 1 patient in the control group did not receive the treatment due to the onset of a pulmonary aneurysm. Therefore, 14 patients in the IMT group and 15 patients in the control group were included in the analyses. Patient demographic characteristics, diagnoses, functional class, and medical therapy are presented in Table 1. There were no significant differences in demographic and clinical variables between the groups. Both groups were heterogeneous and included patients with PAH and other PAH-associated
T a b l e 1 • Baseline Patient Characteristicsa All Patients IMT Group (n = 31) (n = 14)
Control Group (n = 17)
49.7 ± 12.4
46.8 ± 15.6
52.2 ± 8.8
25 (80.6)
11 (78.6)
14 (82.4)
BMI, kg/m
26.7 ± 6.1
25.6 ± 3.7
27.6 ± 7.5
Duration of disease, y
5.6 ± 4.6
5.7 ± 4.6
5.4 ± 4.7
67.3 ± 31.8
77.1 ± 34.7
59.5 ± 28.1
Age, y Female, n (%) 2
Mean PAP, mm Hg
WHO/NYHA functional class, n (%) Class II
16 (51.6)
7 (50)
9 (52.9)
Class III
15 (48.4)
7 (50)
8 (47.1)
Idiopathic PAH
8 (25.8)
3 (21.4)
5 (29.4)
PAH etiology, n (%) Scleroderma
12 (38.7)
5 (35.7)
7 (41.2)
Rheumatoid arthritis
4 (12.9)
2 (14.3)
2 (11.8)
Congenital heart diseases
7 (22.6)
4 (28.6)
3 (17.6)
Bosentan
10 (32.3)
5 (36)
5 (29.4)
Ilioprost
7 (22.6)
2 (14.2)
5 (29.4)
Drug therapy, n (%)
3 (9.7)
2 (14.2)
1 (5.8)
Anticoagulant therapy
Sildenafil
17 (54.8)
10 (71.4)
7 (41.2)
Nifedipine
5 (16.1)
3 (21.4)
2 (11.7)
Abbreviations: BMI, body mass index; IMT, inspiratory muscle training; NYHA, New York Heart Association; PAH, pulmonary artery hypertension; PAP, pulmonary artery pressure; WHO, World Health Organization. a All continuous data presented as mean ± SD. No significant differences between groups for all variables.
200 / Journal of Cardiopulmonary Rehabilitation and Prevention 2015;35:198-206
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Copyright © 2015 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.
JCRP-D-14-00068_LR 200
10/04/15 7:32 PM
weeks of training, MIP, MIP percentage predicted, MEP, and MEP percentage predicted were significantly improved in the IMT group but not in the control group. After the intervention, only 2 (14%) patients in the treatment group had inspiratory muscle weakness, whereas 10 (60%) patients in the control group were still experiencing inspiratory muscle weakness. Inspiratory muscle training resulted in a mean improvement of 26.14 ± 12.15 cmH2O in MIP in the intervention group, whereas the mean change in MIP was a nonsignificant 5.87 ± 12.64 cmH2O for the control group (Figure 1A). There was also a significant difference between the change in MEP between the intervention and control groups (10.00 ± 8.28 cmH2O and 2.80 ± 9.81 cmH2O, respectively) (Figure 1B; P < .05).
conditions, such as congenital heart disease, scleroderma, and rheumatoid arthritis. The IMT intervention was well tolerated by all of the patients, and there were no syncope or presyncope episodes, arrhythmias, or respiratory complications. No significant changes were detected in vital signs during and recovery from the treatment. Only 1 patient suffered from muscle soreness in the first treatment session, although he or she did not stop the training. Patients demonstrated good adherence to the IMT program, and there were no training dropouts.
Pulmonary Function Table 2 shows the results of lung function testing. In the intervention group, percentages of predicted for FEV1 and FVC increased significantly after IMT training. There were no significant changes in lung function testing variables for the control group after the sham IMT. A significant difference in FEV1 percentage predicted was found between the 2 groups. The baseline FEV1 percentage predicted correlated with MIP (r = 0.480; P = .007) and 6MWT distance (r = 0.567; P < .001) in all PAH patients.
Functional Capacity Table 3 shows the data obtained during the 6MWT before and after the training. No statistically significant differences were observed in heart rate, oxygen saturation, lower limb muscle fatigue, and dyspnea perception after training (Table 3). However, a statistically significant improvement was observed in the distance walked and percentage of predicted walk distance. There was a 50-m increase in the mean distance walked in the IMT group. There were no significant changes in the 6MWT distance or the percentage of predicted distance in the control group.
Respiratory Muscle Strength Ten patients (71%) in the IMT group and 11 patients (65%) in the control group had inspiratory muscle weakness at baseline (MIP
