ORIGINAL ARTICLE


https://doi.org/10.5005/jp-journals-11010-1081
Indian Journal of Respiratory Care
Volume 12 | Issue 4 | Year 2023

Ultrasound Evaluation of Diaphragm Motion in Various Body Positions in Normal Adults in Age-group of 20–30 Years: A Pilot Study


Rachna D Arora1https://orcid.org/0000-0001-7724-2823, Madhura R Patil2https://orcid.org/0000-0002-6127-7826, Shenaz AZ Saifi3, Trushna S Khude4

1,2Physiotherapy School and Centre, Topiwala National Medical College and Bai Yamunabai Laxman Nair Charitable Hospital, Mumbai, Maharashtra, India

3,4Department of Radiology, Topiwala National Medical College and Bai Yamunabai Laxman Nair Charitable Hospital, Mumbai, Maharashtra, India

Corresponding Author: Madhura R Patil, Physiotherapy School and Centre, Topiwala National Medical College and Bai Yamunabai Laxman Nair Charitable Hospital, Mumbai, Maharashtra, India, Phone: +91 8425958871, e-mail: madhurapatil313@gmail.com

Received: 07 July 2023; Accepted: 30 November 2023; Published on: 18 January 2024

ABSTRACT

Aims and background: Body positioning is a noninvasive therapeutic intervention used by physiotherapists, with significant effects on and benefits for pulmonary function and oxygenation. It influences ventilation distribution, perfusion, alveolar opening pressure, and diaphragmatic mechanics. This study is to assess diaphragm motion using M-mode ultrasonography (USG) in body positions of supine, side-lying, half-lying, sitting, and forward-lean sitting which are commonly used in treating respiratory patients.

Materials and methods: A total of 40 healthy adults, (20 males and 20 females) nonsmokers, with normal body mass index (BMI), in the age-group of 20–30 years were enrolled after approval from the Institutional Ethics Committee. The study was conducted in collaboration with the Radiology Department of Tertiary Health Care Hospital. USG for right diaphragm motion was done using M-mode. The transducer was placed transversely on the anterior axillary line over the lower intercostal space and a three-layered image was taken. Right, diaphragm motion was assessed with subjects breathing normally and positioned supine, left-side lying, sitting, forward-lean sitting, and half-lying position. Three measurements were recorded and the highest reading was considered. Data was collected and analysis was done using Statistical Package for the Social Sciences (SPSS) version 16.

Results: The right diaphragm motion was 60.04 ± 6.01 mm in supine, 39.59 ± 7.81 mm in left-side lying, 61.27 ± 5.93 mm in half-lying, 41.38 ± 7.41 mm in sitting and 38.68 ± 6.32 mm in forward-lean sitting. Diaphragm motion was highest in half-lying followed by supine, sitting, and forward-lean positions (p = 0.001). There was no significant difference between diaphragm motion in males and females (p > 0.001).

Conclusion: In healthy subjects, diaphragm motion was significantly influenced by body position and was found higher in the supine and half-lying positions.

Clinical significance: Ultrasonography (USG) evaluates diaphragmatic motion, useful in pulmonary rehabilitation. Diaphragm motion is highest in supine and half-lying positions, suggesting effective breathing exercises in these positions.

How to cite this article: Arora RD, Patil MR, Saifi SA, et al. Ultrasound Evaluation of Diaphragm Motion in Various Body Positions in Normal Adults in Age-group of 20–30 Years: A Pilot Study. Indian J Respir Care 2023;12(4):320–324.

Source of support: Nil

Conflict of interest: None

Keywords: Lung ultrasound, Respiratory muscle, Ultrasonography chest

INTRODUCTION

The diaphragm is a primary Inspiratory muscle, it plays a vital role in maintaining the necessary optimal ventilation of the lungs and therefore adequate oxygenation.1 It is a double dome musculotendinous structure located at the inferior aspect of the ribcage positioned at the lower aspect of the ribcage, serving as the lower boundary of the thoracic cavity and the upper boundary of the abdominal cavity. When the diaphragm contracts, it shortens and descends into the abdominal cavity, and when it relaxes it moves upward. When this diaphragm motion is hampered, for example in patients with chronic obstructive pulmonary disease (COPD), ascites, etc., subjects experience breathlessness. Weakness of the diaphragm muscle can lead to type 2 respiratory failure.2

Diaphragm motion is influenced by various body positions, due to the effects of gravity and pressure exerted by abdominal organs. In a supine position (lying on the back), the diaphragm has to contract against the pressure or resistance exerted by abdominal organs whereas in a sitting position, gravity facilitates diaphragm motion. It is assumed that with a change in position, the diaphragm’s capacity to generate tension is diminished. The peripheral fibers of the diaphragm extend in a cranial-dorsal direction from their points of attachment, thus aligning the fibers parallel to the inner edges of the lower ribs. During the contraction of the diaphragm, these fibers apply an upward force on these ribs, thereby moving them upward (Bucket-handle movement). Conversely, when the diaphragm is flattened and shortened, like in COPD, or obesity, the peripheral fibers are aligned perpendicular to the inner edges of the lower ribs. Here, the contraction causes the inner ribs to move inward instead of upward, thus altering the diaphragm biomechanics.3

Body positioning refers to the intentional placement of the patient or a body part to enhance both physical health and/or mental well-being.3 Therapeutic body positions are used for optimizing cardiopulmonary function and oxygen transport as an integral part of a pulmonary rehabilitation program. Positions such as supine, side-lying (lying on one side), half-lying (propped up), and sitting positions are commonly used in pulmonary rehabilitation for respiratory patients. These positions are used to perform breathing techniques such as deep breathing, pursed-lip breathing, and huffing (forced expiration with open glottis) to enhance ventilation. Additionally, postural drainage and the use of positive expiratory pressure devices like acapella, flutter, lung flute, etc. may be applied with these positions to help mucus clearance from the airways.4

However, the impact of different body positions on diaphragmatic motion is not well understood. Understanding the influence of various positions on diaphragmatic motion can help us in choosing the best position for diaphragmatic breathing exercises and ultimately enhance the patient’s quality of life.5 The assessment of diaphragm motion using ultrasonography (USG) is a noninvasive, reliable diagnostic tool that is more readily available with portable high-resolution machines. With the growing prevalence of high-resolution, portable, and real-time ultrasound technology, it is now convenient to visualize the diaphragm in an outpatient setting.6 Motion (M) mode of ultrasound is a simple, less time-consuming, easy, and accurate method that is used to evaluate the motion of moving structures.7 The transducer probe is positioned along the anterior axillary line at the intercostal area and oriented in a medial, cephalad, and dorsal direction. This position ensures that the ultrasound beam accurately reaches the posterior portion of the right diaphragm vault at an almost perpendicular angle, facilitating precise measurements of diaphragmatic motion.8

Previous studies have reported the effect of body positions on hemodynamic parameters and lung function. There are limited studies available on the assessment of diaphragm motion in various body positions. A study by Yamaguti et al. assessed diaphragm motion using ultrasound in sitting and supine positions. Their study showed that diaphragm motion was more in a supine position than sitting.1 A similar study was done by Takazakura et al., which used magnetic resonance imaging to assess diaphragm motion in sitting and supine. Positions like half-lying position, side-lying, and forward-lean sitting positions which are routinely used in physiotherapy were not included. Here, subjects were exposed to radiation. Also, magnetic resonance imaging (MRI) is a costly investigation.5

A better understanding of diaphragm motion in various body positions will help in choosing effective body positions for breathing retraining and diaphragm strengthening in rehabilitation sessions. Hence, the objective of this study was to evaluate diaphragm motion using M-mode USG in commonly used body positions of supine, side-lying, half-lying, sitting, and forward-lean sitting by Physiotherapists in treating respiratory patients.

MATERIALS AND METHODS

The Institutional Ethics Committee (ECARP/2019/01) approval was taken before commencing the study. A total of 40 healthy subjects (20 males and 20 females) were recruited in the study after screening for exclusion criteria [body mass index (BMI) >25, peak expiratory flow rate <200 mL/minute,9 medical history of any cardiopulmonary and neuromuscular disease, and pregnant women) and the inclusion criteria (healthy adults and age-group between 20 and 30 years) (Fig. 1). The participants were positioned in various positions by the physiotherapist which included supine, side-lying, erect sitting, forward-lean sitting, and half-lying position. USG for right diaphragm motion was done by a radiologist using M-mode (Fig. 2).10 A high-resolution ultrasound machine (two-dimensional/three-dimensional Toshiba Xiaro 100) was used in this study with a convex probe (Curvilinear cluster of differentiation 2) with a frequency range of 2.5–3.5 MHz. The placement of the probe was precisely between the midclavicular and anterior axillary lines, within the subcostal region which was then gently guided in a medial, cranial, and dorsal direction, ensuring that the beam of ultrasound intersected the posterior third of the right hemi-diaphragm at a perpendicular angle.11,12

Fig. 1: Methodology. The above figure shows the inclusion and exclusion criteria and study procedure

Fig. 2: Ultrasound evaluation of diaphragm motion in various body positions. The above figure shows an assessment of right diaphragm motion in supine, left-side lying, half-lying, sitting, and forward-lean sitting

During this procedure, subjects were asked to breathe normally. Diaphragm motion was calculated by measuring the distance between the peak of the dome during inspiration and the flat baseline in expiration in millimeters (Fig. 3). Three measurements were taken in each position, and the highest value was selected for statistical analysis. Data was documented and statistically analyzed using Statistical Package for the Social Sciences (SPSS) software version 16 (IBM Chicago, Illinois, United States of America). The normality of data distribution was assessed using the Shapiro–Wilk test. To compare the mean of diaphragm motion in supine, left-side lying, half-lying, sitting, and forward-lean sitting positions repeated measures analysis of variance (ANOVA) test was used. A post hoc Tukey’s test was conducted to find out which position exhibited the greatest diaphragm motion. Furthermore, an independent t-test was done to assess the statistical difference between the diaphragm motion of male and female participants.

Fig. 3: Measurement of right diaphragm motion using M-mode. The above figure shows the calculation of diaphragm motion by taking the distance between the baseline during expiration and the peak during inspiration

RESULTS

The mean age of subjects was 23.45 ± 1.99 years and included 20 females with a mean of 23.55 ± 1.93 years and 20 males with a mean age of 23.35 ± 2.10 years. Table 1 and Figure 4 show right diaphragm motion in various positions. Repeated measures ANOVA showed a statistically significant difference in diaphragm motion in supine, left-side lying, half-lying, sitting, and forward-lean sitting (p < 0.001). Post hoc analysis revealed that higher diaphragm motion was seen in half-lying and supine positions as compared to left-side lying, erect sitting, and forward-lean sitting (p = 0.001) (Fig. 5). There was no significant difference in diaphragm motion in left-side lying, erect sitting, and forward-lean sitting indicating that the diaphragm motion is almost similar in these positions (p > 0.001). There was no statistically significant difference in diaphragm motion between males and females (p > 0.001).

Table 1: Diaphragm motion in various body positions
Positions Mean (mm) Standard deviation
Supine 60.0425 6.10031
Left-side lying 39.5925 7.81522
Half-lying 61.2700 5.93578
Sitting 41.3875 7.41019
Forward-lean sitting 38.3625 6.32012

The above table shows the right diaphragm motion in supine was 60.04 ± 6.10 mm in supine, 39.59 ± 7.81 mm in left-side lying, 61.27 ± 5.93 mm in half-lying, 41.38 ± 7.41 mm in sitting, and 38.68 ± 6.32 mm in forward-lean sitting

Fig. 4: Box and plot distribution of diaphragm motion in various positions. The above figure shows the calculation of diaphragm motion by taking the distance between the baseline, during expiration and the peak during inspiration

Fig. 5: Post hoc analysis for different body positions. The above graph shows a multivariate comparison of diaphragm motion in various body positions with half-lying showing the highest diaphragm motion followed by supine, erect sitting, forward-lean, sitting, and left-side lying

DISCUSSION

The study investigated diaphragm motion using M-mode ultrasound in various body positions in healthy young adults in the age-group of 20–30 years. This study assessed the right diaphragm due to easier accessibility to assess right diaphragm motion as compared to the left.13 The right diaphragm’s highest motion was observed in the half-lying position, followed by supine, sitting, and forward-lean positions. Left side-lying showed the least diaphragm motion. This suggests that body position significantly affects diaphragm motion.

Houston et al. in their study assessed diaphragm motion using M-mode USG and reported that diaphragm motion was greater in the supine position when compared to sitting or standing positions while breathing at equivalent inspiratory capacity. The authors attributed it to the biomechanical alteration of the diaphragm. They suggested that a change in position alters the range of motion, positioning, and coordination of the thoracic spinal vertebrae and the ribcage which in turn affects elasticity of the ribcage.14,16 The variation in diaphragm motion with body positions can be attributed to the influence of gravity on diaphragm length-tension relation, as well as alterations in intra-abdominal pressure and lung volume. In the supine position, the intra-abdominal pressure is reduced thereby facilitating diaphragm motion. Conversely, increased intra-abdominal pressure in sitting constraints diaphragm motion.

Furthermore, although the diaphragm exhibited greater motion in the supine position, the amount of air inspired was lower as compared to the sitting position. This suggests that the motion of the lower ribcage also impacts lung volume during respiration. When breathing in the supine position where the thoracic cage is stabilized, outward movement of the lower thoracic cage is reduced, leading to reduced inspired volume despite the diaphragm’s increased motion.17,18 Similar findings were seen in a study done by Takazakura et al. In their study, MRI was used to assess diaphragm motion.17

This study also showed that diaphragm motion was lower in sitting and forward-lean sitting as compared to supine and half-lying positions. To maintain a typical breathing pattern, the diaphragm muscle must contract efficiently. In a forward-lean sitting position, the diaphragm’s capacity to generate the necessary force for contraction is diminished due to increased intra-abdominal pressure, changes in the configuration of the ribcage, and the dynamics of the chest wall resulting in decreased diaphragm contraction and thereby motion.15,18 Sitting position is commonly used by physiotherapists to teach breathing exercises in an outpatient department setting. Breathless patients assume a forward-lean position to relieve breathlessness. It is also one of the relaxed positions used by physiotherapists. This position is said to relax the upper chest and facilitate diaphragm motion. However, this study shows that diaphragm motion is the least in these positions and should not be used to teach breathing exercises.

The side-lying position exhibited the lowest diaphragm motion. When lying on one’s side, gravity pushes the abdominal viscera toward the abdominal organs on the dependent side, elevating the intra-abdominal pressure on that side. This increased pressure diminishes the area where the diaphragm is closely adjacent to the abdominal wall on the dependent side, leading to increased muscular contraction of the diaphragm on that side.14,19 In this study, the nondependent diaphragm motion was studied. This could probably explain the low diaphragm motion seen.

The findings seen have potential implications for the use of USG in the assessment of diaphragm motion in clinical practice. Diaphragm motion using M-mode ultrasound is an easy, safe, and radiation-free technique frequently used in the assessment of diaphragm in various clinical settings.11 This study showed that the body position has a significant influence on diaphragm motion. Diaphragm motion was maximum in supine followed by half-lying and least in sitting, forward-lean, and side-lying positions. Therefore, diaphragmatic breathing exercises should be taught in supine or half-lying positions. This study also provides data on the normal diaphragm motion in healthy young adults, which can serve as a baseline for future studies examining diaphragm motion in chronic respiratory disease. This study was conducted on a small sample size of 30 individuals, which was one of the limitations.

CONCLUSION

Body position has a significant effect on diaphragm motion. Specifically, diaphragm motion is found to be higher in the supine and half-lying positions among healthy subjects. This study also demonstrates the clinical utility of assessing diaphragm motion. The findings suggest that breathing exercises should be performed in the supine and half-lying positions wherein the diaphragm motion is maximum.

Clinical Significance

Ultrasonography (USG) is a valuable method for assessing diaphragmatic motion, making it an effective tool for evaluating the outcomes of pulmonary rehabilitation. Diaphragmatic motion, which can serve as an indicator of respiratory function, was found to be highest in supine and half-lying positions. Therefore, prescribing breathing exercises in these positions can optimize diaphragm function and enhance the effectiveness of pulmonary rehabilitation programs. This study also establishes normal diaphragm motion data in healthy young adults, serving as a foundation for future research targeting diaphragm motion in chronic respiratory diseases.

ORCID

Rachna D Arora https://orcid.org/0000-0001-7724-2823

Madhura R Patil https://orcid.org/0000-0002-6127-7826

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