1. Introduction
Chronic Obstructive Pulmonary Disease (COPD) is one of the leading causes of mortality in developing countries and has an increasing rate. It is the fourth leading cause of death in the United States. According to estimates by the World Association of Chronic Obstructive Pulmonary Diseases, COPD will be ranked 3 out of the 6 most common causes of death in the world by 2020 and is expected to become the fifth most debilitating disease [1]. The patients with COPD lose bodyweight and alter diaphragm muscle with reduced thickness [8]. In Diaphragmatic Breathing (DB), the focus is on the diaphragm muscle as the most important respiratory muscle. In this type of exercise, we would like to know whether the diaphragm muscle alone can improve pulmonary function in these patients [9]. In Iran, because of the weakness in disease prevention, these techniques are not considered a part of the complementary program of clinical treatment for the promotion of patients’ health.
2. Materials and Methods
This research is a quasi-experimental study with a pre-test-post-test design conducted in 2017. The sampling was performed for 2 months on patients with COPD referred to Velayat Hospital in Qazvin city, Iran. Sixteen patients with a Mean±SD age of 55±5.4 years suffering from COPD with moderate severity were selected using purposive and convenience sampling method. They were randomly assigned into two groups of DB (n=8) and control (n=8) by the specialist. The diagnosis of COPD was based on a spirometry test, where the ratio of Forced Expiratory Volume (FEV1) to the Forced Vital Capacity (FVC) should be less than 70%. All patients had no cardiovascular, hepatic, gastrointestinal, and peripheral edema problems, and they were all in the intermediate stage of the disease. 
All subjects were matched by a pulmonary practitioner for drug use. Laboratory instruments and a demographic form were used to confirm the inclusion criteria. These criteria were the stability of the patient's medical condition to attend the exercise program, no history of chronic diseases, and no definitive diagnosis of the disease by a specialist. The diaphragmatic breathing technique was taught to the patients in one training session. Before the start of the exercises, the patients' Respiration Rate (RR) was recorded per minute while resting. Lung function was tested by the spirometer measuring FEV1 and FEV1/FVC ratio. Then, their Maximal Inspiratory Pressure (MIP) was measured by a body box in the hospital in the presence of a physician and laboratory expert. The DB group received diaphragmatic breathing exercises for 8 weeks, 3 sessions per week, each taking 1 hour. The control group received no training. At the end of the sessions, pulmonary factors of FEV1, MIP, and RR were measured and recorded again. The data were analyzed using ANOVA and Tukey post hoc test at a significant level of P<0.05.
3. Results
The results of the Independent t-test showed no significant difference between the two groups regarding age, body mass index, and weight (P˃0.05), indicating the homogeneity of the two groups in terms of demographic characteristics. The results of the Shapiro-Wilk test indicated the normal distribution of the quantitative data; hence, parametric methods were used to analyze the data. The results of the study showed that the patients, who received breathing exercise, had higher FEV1 compared to its pre-test score, and the increase was statistically significant (P˂0.05). 
The FEV1 before the workout was 68.2 and increased to 69.2 after exercise, indicating the effect of DB exercise in this group. There was a significant decrease in RR in the DB group, which was a sign of improvement and change in the respiratory pattern of patients from shallow and rapid breathing to deep and slow breathing (P=0.00). Various studies have used the MIP variable to evaluate the diaphragm muscle since it is the best indicator for this evaluation. The amount of MIP in the DB group was 73.7 before the intervention and significantly increased to 84.7 after the intervention (P=0.00). Table 1 presents the overall comparison of the DB and control groups before and after intervention by the paired t-test. According to the obtained values, the pre-test and post-test scores of pulmonary factors in the control group were almost equal, and none of them increased significantly (P>0.05).



4. Conclusion
Patients with COPD have superficial, rapid, and inadequate breathing. Fear of exposure to the shortness of breath prevents physical activity in these patients [11]. Finding the best method for its treatment has always been the subject of various studies. In this regard, physiotherapists have tried to increase lung function and respiratory capacity by using respiratory muscle training and exercises [12]. The therapeutic outcomes in these patients not only should be focused on pulmonary function changes but also should affect the quality of life of these patients. The present study showed that diaphragmatic breathing exercise was effective in improving the pulmonary function and respiratory pattern of patients with COPD. This type of training can be used for pulmonary rehabilitation to reduce symptoms and prevent worsening. There is a need for a pulmonary rehabilitation program in health centers because of the impact of this type of diaphragmatic breathing exercise.
Ethical Considerations
Compliance with ethical guidelines
This article has a code of ethics from Islamic Azad University of Science and Research Branch Tehran. All the ethics of research are adhered to. Written consent was obtained from all participants in the study and all participants were fully aware of the research process and whenever possible, they could be excluded from the study. All participants' information was kept confidential.
Funding
This article is taken from the PhD. thesis of Mojtaba Amini, Department of Physical Education and Sports Science, Faculty of Humanities and Social Sciences, Science and Research Branch, Islamic Azad University.
Authors' contributions
All authors contributed in preparing this article.
Conflicts of interest
The authors declared no conflict of interest.
Acknowledgements
We would like to express our gratitude to the efforts and cooperation of the management and the hard working staff of Qazvin hospital in the province, who have been very helpful in carrying out this research.


 

1. Yeung EWF, French P, Leung AOS. The impact of hospice inpatient care on the quality of life of patients terminally ill with cancer. Cancer Nursing. 1999; 22(5):350-7. [DOI:10.1097/00002820-199910000-00003] [PMID]
2. Phipps WJ. Medical-surgical nursing: Health and illness perspectives. Maryland Heights: Mosby; 2003.
3. Thomas MJ, Simpson J, Riley R, Grant E. The impact of home-based physiotherapy interventions on breathlessness during activities of daily living in severe COPD: A systematic review. Physiotherapy. 2010; 96(2):108-19. [DOI:10.1016/j.physio.2009.09.006] [PMID]
4. Ulrich SP, Canale SW, Wendell SA. Nursing care planning guides: A nursing diagnosis approach. Philadelphia: Saunders Company; 1986.
5. Woo K. A pilot study to examine the relationships of dyspnoea, physical activity and fatigue in patients with chronic obstructive pulmonary disease. Journal of Clinical Nursing. 2000; 9(4):526-33. [DOI:10.1046/j.1365-2702.2000.00361.x] [PMID]
6. Meek PM, Lareau SC. Critical outcomes in pulmonary rehabilitation: Assessment and evaluation of dyspnea and fatigue. Journal of Rehabilitation Research and Development. 2003; 40(5):13-24. [DOI:10.1682/JRRD.2003.10.0013] [PMID]
7. Cazzola M, Donner CF, Hanania NA. One hundred years of Chronic Obstructive Pulmonary Disease (COPD). Respiratory Medicine. 2007; 101(6):1049-65. [DOI:10.1016/j.rmed.2007.01.015] [PMID]
8. Arora NS, Rochester DF. Effect of body weight and muscularity on human diaphragm muscle mass, thickness, and area. Journal of Applied Physiology. 1982; 52(1):64-70. [DOI:10.1152/jappl.1982.52.1.64] [PMID]
9. Bernardi E, Pomidori L, Bassal F, Contoli M, Cogo A. Respiratory muscle training with normocapnic hyperpnea improves ventilatory pattern and thoracoabdominal coordination, and reduces oxygen desaturation during endurance exercise testing in COPD patients. International Journal of Chronic Obstructive Pulmonary Disease. 2015; 10:1899-906. [DOI:10.2147/COPD.S88609] [PMID] [PMCID]
10. McConnell AK. Respiratory muscle training as an ergogenic aid. Journal of Exercise Science & Fitness. 2009; 7(2):S18-S27. [DOI:10.1016/S1728-869X(09)60019-8]
11. Ram FS, Robinson SM, Black PN. Effects of physical training in asthma: A systematic review. British Journal of Sports Medicine. 2000; 34(3):162-7. [DOI:10.1136/bjsm.34.3.162] [PMID] [PMCID]
12. Brunner LS. Brunner & Suddarth’s textbook of medical-surgical nursing. Philadelphia: Lippincott Williams & Wilkins; 2010.
13. Charususin N, Gosselink R, Decramer M, McConnell A, Saey D, Maltais F, et al. Inspiratory muscle training protocol for patients with chronic obstructive pulmonary disease (IMTCO study): A multicentre randomised controlled trial. BMJ Open. 2013; 3(8):e003101. [DOI:10.1136/bmjopen-2013-003101] [PMID] [PMCID]
14. Pryor JA, Prasad AS. Physiotherapy for respiratory and cardiac problems: Adults and paediatrics. Edinburgh: Elsevier Health Sciences; 2008.
15. Belman MJ, Shadmehr R. Targeted resistive ventilatory muscle training in chronic obstructive pulmonary disease. Journal of Applied Physiology. 1988; 65(6):2726-35. [DOI:10.1152/jappl.1988.65.6.2726] [PMID]
16. Bellemare F, Grassino A. Evaluation of human diaphragm fatigue. Journal of Applied Physiology. 1982; 53(5):1196-206. [DOI:10.1152/jappl.1982.53.5.1196] [PMID]
17. Anthoisen N, Connett J, Kiley J, Altose M, Bailey W, Buist A, et al. Effects of smoking intervention and the Use of an inhaled anticholinergic bronchodilator on the rate of decline of FEV1. The lung health study. Survey of Anesthesiology. 1995; 39(5):332. [DOI:10.1097/00132586-199510000-00063]
18. Ray A, Pendergast D, Lundgren C. Respiratory muscle training improves swimming endurance at depth. Undersea & Hyperbaric Medicine. 2008; 35(3):185-96. [PMID]
19. Kabitz HJ, Walterspacher S, Walker D, Windisch W. Inspiratory muscle strength in chronic obstructive pulmonary disease depending on disease severity. Clinical Science. 2007; 113(5):243-9. [DOI:10.1042/CS20060362] [PMID]
20. Kang JI, Jeong DK, Choi H. The effects of breathing exercise types on respiratory muscle activity and body function in patients with mild chronic obstructive pulmonary disease. Journal of Physical Therapy Science. 2016; 28(2):500-5. [DOI:10.1589/jpts.28.500] [PMID] [PMCID]
21. Cancelliero-Gaiad KM, Ike D, Pantoni CB, Borghi-Silva A, Costa D. Respiratory pattern of diaphragmatic breathing and pilates breathing in COPD subjects. Brazilian Journal of Physical Therapy. 2014; 18(4):291-9. [DOI:10.1590/bjpt-rbf.2014.0042] [PMID] [PMCID]
22. Redelmeier DA, Bayoumi AM, Goldstein RS, Guyatt GH. Interpreting small differences in functional status: The Six Minute Walk test in chronic lung disease patients. American Journal of Respiratory and Critical Care Medicine. 1997; 155(4):1278-82. [DOI:10.1164/ajrccm.155.4.9105067] [PMID]
23. Yamaguti WP, Claudino RC, Neto AP, Chammas MC, Gomes AC, Salge JM, et al. Diaphragmatic breathing training program improves abdominal motion during natural breathing in patients with chronic obstructive pulmonary disease: A randomized controlled trial. Archives of Physical Medicine and Rehabilitation. 2012; 93(4):571-7. [DOI:10.1016/j.apmr.2011.11.026] [PMID]
24. Gosselink R, Wagenaar RC, Rijswijk H, Sargeant AJ, Decramer M. Diaphragmatic breathing reduces efficiency of breathing in patients with chronic obstructive pulmonary disease. American Journal of Respiratory and Critical Care Medicine. 1995; 151(4):1136-42. [DOI:10.1164/ajrccm/151.4.1136] [PMID]