The effect of diaphragmatic stretch technique on diaphragmatic excursion in chronic obstructive pulmonary disease

Aishwarya Nair1, Krishnaprasad K M*1, Gopala Krishna Alaparthi2, Shyam Krishnan3, Santhosh Rai4 1Nitte Institute of Physiotherapy, NITTE (Deemed to be University), Mangalore, Karnataka, 575018, India 2Department of Physiotherapy, College of Health Sciences, University of Sharjah, United Arab Emirates 3Department of Physiotherapy, Kasturba Medical College, Manipal Academy of Higher Education, Bejai, Mangalore 575004, India 4Department of Radiodiagnosis, Kasturba Medical College, Manipal Academy of Higher Education, Mangalore 575004, India


INTRODUCTION
'Chronic Obstructive Pulmonary Disease' (COPD) is currently the fourth leading cause of death in the world, accounting for 6% deaths globally. Now, it is considered as a preventable and treatable disease caused by signi icant exposure to noxious gasses or particles (Singh et al., 2019). The pathology of COPD includes decreasing parenchymal tethering of the airways, loss of alveolar surface area, narrowing of the peripheral airways,air trapping and pulmonary hyperin lation (Yamaguti et al., 2008). These intrapulmonary changes can be traced to several pathological changes like peribronchial ibrosis, sub-mucosal gland hypertrophy, increased mucus hypersecretion,and an increase in airway smooth muscle mass. Airway wall remodelling in COPD can be mainly attributed to epithelial metaplasia leading to airway wall thickening with TGF-β being proposed as an essential mediator (Lee, 2017). These pathological changes exhibit as persistent air low limitation, especially expiratory low limitation, which prolongs expiration leading to pulmonary hyperin lation (Hellebrandova et al., 2016).
The diaphragm is the primary muscle of ventilation, accounting for approximately 70% to 80% of inspiration force during quiet breathing. During normal quiet breathing, there is a descent of the diaphragm as the ibres contract. With a deeper breath, as the diaphragm reaches the end of its contraction, the ibres become more horizontally aligned, lattening the dome of the diaphragm and thereby increasing the thoracic size and intra-abdominal pressure. The resultant increase in thoracic size causes a reduction in the intrapulmonary pressure that is responsible for inspiration (Levangie and Norkin, 2000).
COPD is typically associated with weakness, shortening and mechanical disadvantage of the inspiratory muscles, especially diaphragm, mainly due to the changed length-strength relationship and their remodelling (Hellebrandova et al., 2016). In persons with chronic obstructive pulmonary disease (COPD), chronic hyperin lation of the lungs results in a resting position of the diaphragm to be lower (more lattened) and shorter (by 28-40%) than normal (Levangie and Norkin, 2000;Yamaguti et al., 2008). This hyperin lation creates a "threshold load" that the diaphragm has to overcome to initiate an inspiratory low. These changes cause an increase in the work of breathing, leading to high oxygen cost, hypo-ventilation and reduction in exercise tolerance and functional capacity which makes it a potential target for therapeutic intervention (O'Donnell and Laveneziana, 2006).
The mainstay treatments for COPD has been pharmacological Therapy and pulmonary rehabilitation for several years, however, there has been an encouraging number of studies in the osteopathic and chiropractic literature that have tested the use of manual therapy techniques in chronic pulmonary diseases (Howell et al., 1975;Noll et al., 2009).
Manual Therapy has shown to target mainly the musculoskeletal structure surrounding the lungs, subtly rearranging and resetting the mechanics of respiration (for example, the lexibility of chest wall and thoracic expansion) in certain chronic respi-ratory diseases. This may indirectly lead to an improvement in functional capacity and exercise tolerance thereby having a positive impact on ventilation (Bockenhauer et al., 2002;Engel and Vemulpad, 2011;Yamaguti et al., 2008).
The Diaphragmatic Stretch Technique targets the diaphragm to improve its dome shape in the resting position (as opposed to the lattened state in COPD patients). It thrives on creating and maintaining a pressure gradient between the thorax and abdomen (Chaitow et al., 2002). There was a lack of retrievable data available that tested the effect of Diaphragmatic stretching technique on diaphragmatic excursion in patients with COPD using Ultrasound as an outcome measure. This study aims to ind the effects of Diaphragmatic stretch on a diaphragmatic excursion in patients with COPD.

Inclusion criteria
1. Patients with clinically stable COPD who are referred for Physiotherapy/ Pulmonary Rehabilitation by a physician. 2. Patients with GOLD level 1 and 2 classi ications of air low limitation severity in COPD (postbronchodilator FEV1) according to the GOLD criteria.

Exclusion criteria
1. Patients with a history of exacerbation of COPD in the past month.
3. Patients who have undergone recent surgery of the thorax, abdomen or head and neck.
4. Patients who have a recent history of trauma to the thorax, abdomen or head and neck 5. Patients with chest wall and trunkdeformities (example: scoliosis) 6. History of psychiatric illness or dif iculty in comprehending commands and following instructions.

Study procedure
After the approval from the Ethical Committee of a Deemed to be University in Mangalore, Karnataka, eligible patients were selected based on the checklist of inclusion and exclusion criteria.    They were also categorised as having mild or moderate COPD based on their PFT values crossreferenced with the inclusion criteria. After explaining the purpose of the study to the subjects, written informed consent was obtained before inducting them into the study.
The demographic data were collected, and preintervention values of both the outcome measures were taken. The primary outcome measure that is Diaphragm mobility was assessed using Ultrasound by a consultant radiologist. Therapist performed the secondary outcome measure that is Chest Expansion using an Inch tape as per standard guidelines.
After this initial procedures, the therapist performed the Diaphragmatic Stretch Technique with the co-operation of the patient in 2 sets (each set consisting of 10 deep breaths) with a 1-minute interval between the sets. Immediately after the intervention, the two outcome measure was assessed as before.

Diaphragmatic stretch technique
The subjects were asked to sit on a couch or stool without back support with the trunk slightly rounded to relax the Rectus Abdominis muscle for the technique.
The therapist positions themselves behind the patient to perform the technique and places their hands around the thoracic cage with the ingers over the bilateral subcostal margin. The therapist irmly holds on to the lower ribs and eases it caudally at the subcostal margin while the patient is instructed to exhale.
This hold exudes gentle downward traction without any compression to the ribcage and is maintained while the patient takes the next deep inhalation (Chaitow et al., 2002).

Diaphragm excursion
The patient's diaphragm was visualised and documented using Ultrasound 'B' Mode while the patient was in sitting position. The probe was placed in the midclavicular as well as midaxillary lines in the subcostal/ lower ribcage area so that bilateral diaphragm could be seen. The reference points of the diaphragm at maximal inspiration and maximal expiration were taken thrice, and the average of the three was documented (Okura et al., 2017).

Chest expansion
The patients were instructed to breathe in and out maximally while standing or sitting with their hands behind their heads. Measurements were taken at the 4 th intercostal level and xiphoid process level for the documentation of upper and lower chest expansion, respectively (Olsén et al., 2011).

Sample size estimation
A pilot study involving ive clinically stable patients with COPD was conducted with the same study procedure, which later became the foundation to derive a sample size of 20 patients for this interventional study.

RESULTS AND DISCUSSION
A total of 32 patients who were diagnosed with clinically stable mild or moderate COPD were selected. Out of this, seven patients had to be excluded as they had co-morbidities (recent pleural tapping < 20 days back; acute exacerbation < 1 month back). In addition to that, ive patients dropped out due to lack of interest bringing the inal 20 patients as per the sample size.  Table 2 and Table 3. Table 4 summarises the chest expansion values before and after the intervention. There was a difference of 0.76 ± 0.71 (p=0.000) at the level of 4 th intercostal space and 0.62 ±0.64(p=0.000) at the level of the xiphoid process after the intervention.
The present study aimed at inding the effect of Diaphragmatic stretch technique on patients with mild and moderate COPD on diaphragmatic excursion and chest expansion. A statistically signi icant difference in these outcome measures was found after the intervention was administered.
The muscle spindle, which is the sensory organ for the muscle, maybe stimulated due to the muscle stretching, which may be the reason for the result. This directly targets and activates the sensory afferent stimulus, accelerating neuromuscular response. The stretch also renders a mechano-receptor stimulation leading to activation of sympathetic chain ganglia and related structures. These stimulations may contribute to improved sympathetic tone in the lung, increased tension in the muscle, inally improving the viscoelastic properties of the muscle. The technique done in this study may also have had an impact on the respiratory mechanics and the chest wall mobility leading to an increase in chest expansion (Minoguchi et al., 2002;McHugh and Cosgrave, 2009;Bhilpawar and Arora, 2013).
The improved chest wall mobility also points in the direction of stimulation of Golgi tendon organ, which is a receptor in the musculotendinous junction, which would have imposed an inhibitory effect on the muscles working at a mechanical disadvantage (Kokkonen et al., 2007). Astudy done by Noll et al. (2008) has reported a positive result on pulmonary function after the patients underwent the Redoming of Diaphragm technique (Noll et al., 2008). In a study done by González-Álvarez et al. (2016) the diaphragm stretch technique was performed on healthy subjects which has shown an improvement in the posterior chain kinematics (González-Álvarez et al., 2016). Bhilpawar and Arora (2013) conducted a study with a combination of manual Therapy including the diaphragmatic stretch technique or redoming of diaphragm technique which showed a signi icant improvement in chest expansion and improvement in respiratory rate (Bhilpawar and Arora, 2013).
In a study conducted by Abdelaal et al. (2015) showed a signi icant ampli ication of FVC,FEV1 and 6MWT after the administration of Redoming of the Diaphragm technique (Abdelaal et al., 2015). Braga et al. (2016) found that the manual therapy techniques aimed at the diaphragm and ribs had a marginal effect on thoracic mobility (Braga et al., 2016). The future scope for this study includes involving larger populations of COPD categorised to various disease severity and subgroups, performing the intervention for more number of sessions with the addition of different outcome measures, assessing the more long term effects of the diaphragmatic stretch technique.

CONCLUSION
The Diaphragmatic Stretch Technique has a clinically and statistically signi icant effect on the diaphragmatic excursion and chest expansion in patients with mild to moderate COPD. The technique is well tolerated by the patient with COPD without any dif iculty or exacerbation ACKNOWLEDGEMENT I acknowledge the support and guidance given by Dr Gopalkrishna A and Dr Santosh Rai throughout the study.

Funding Support
This study received no funding support from any sources.

Con lict of Interest
The authors declare no con licts of interest.