DIFFERENCES IN DIAPHRAGM AND CHEST WALL EXCURSION DURING RESTING BREATHING DEPENDING ON BODY POSITION: DYNAMIC ANALYSIS BY MRI

S. Hirakawa^1,2, R. Kuroishi¹, K. Sui¹, T. Yamada¹

¹Tokyo Metropolitan University, Graduate School of Human Health Science Department of Physical Therapy, Tokyo, Japan, ²Mitsui Memorial Hospital, Department of Rehabilitation, Tokyo, Japan

Background: Respiratory activity is known to be significantly by body positions, and in clinical settings, positional management by respiratory physiotherapy has been shown to be an effective supportive treatment for respiratory disorders as well as preventing respiratory complications. Although the diaphragm plays a pivotal role in respiration, and valuable information about pulmonary function being provided by diaphragmatic excursion assessment, very limited studies have reported about these excursive movement and chest wall in different positions.

Purpose: In acute clinical situations, patients are often managed in the side-lying and prone positions, and it is of great clinical significance to understand the excursions of the diaphragm and chest wall in these positions. Therefore, in this study we investigated the differences, if any, between the excursion of the diaphragm and chest wall while breathing in the supine, prone, and right and left side-lying positions.

Methods: The excursion of the diaphragm along with the anteroposterior and lateral diameters of the chest wall were dynamically imaged during resting breathing in four positions (supine, prone, right and left side-lying) using magnetic resonance imaging (MRI) in 40 healthy male and female adult subjects, and the amount of excursion was calculated. Friedman's test was used for statistical analysis, and multiple comparisons by Bonferroni correction were performed as a post hoc test. In addition, Mann-Whitney's U test was used to compare the differences between the right and left sides of diaphragm and chest wall excursions, as well as between the male and female subjects.

Results: The diaphragm and chest wall showed significantly greater excursion in the prone position than in the other positions. In the side-lying position, the anteroposterior diameter expansion of the lower chest wall on the unloaded side was significantly greater. However, there was no significant difference between the excursion of the diaphragm and chest wall in the side-lying and that in the supine positions.

Conclusions: The diaphragm does not move uniformly as a single muscle, and its excursion differs depending on its region. In particular, posteriorly the diaphragm shows the largest amount of excursion and is said to contribute strongly to ventilation. In the prone position, the posterior diaphragm is relieved from the pressure from the thoracoabdominal organs and the floor surface, thereby the amount of excursion may be greater than in other positions. Therefore, it would be useful to analyze the diaphragm individually in order to obtain more detailed information in the future.

Implications: The results of this study suggest that the prone position is the most appropriate ‘respiratory management positioning’. Therefore, it is recommended that the patient be placed in a position as close to the prone position as possible for respiratory management. In addition, the side-lying position does not contribute much increasing the diaphragmatic excursion, in turn not increasing the ventilation much, and therefore, should be considered separately from the means to achieve airway clearance.

Funding acknowledgements: 何もない

Keywords:
Diaphragm
Chest wall
Body position

Topics:
Cardiorespiratory
Critical care

Did this work require ethics approval? Yes

Institution: Tokyo Metropolitan University

Committee: Research Ethics Committee, Tokyo Metropolitan University Arakawa Campus

Ethics number: 21055