Diaphragmatic motion in the sitting and supine positions: Healthy subject study using a vertically open magnetic resonance system

Abstract

Purpose: To determine the postural difference of diaphragmatic motion between the sitting and supine positions. Materials and Methods:A total of 10 healthy men were examined using a vertically open 0.5-T magnetic resonance (MR) system. A total of 40 sequential MR images were obtained in both the sitting and supine positions during two to five respiratory cycles. The diaphragmatic excursions (DEs) were measured on three diaphragmatic points of six sagittal planes for both positions. The differences in DEs between the anterior and posterior parts of the diaphragm were also determined.Results: DEs in the supine position were significantly greater than those in the sitting position at 15 of the 18 points. In five of the six sagittal planes, the difference of DE between posterior and anterior points was significantly larger in the supine position than in the sitting position. There have been several investigations on the evaluation of diaphragmatic motion using magnetic resonance imaging (MRI) since Gierada et al (1) first presented it (2-6). However, there is no study in which respiratory function was assessed using MRI in an upright position. For physiological investigation of normal respiratory mechanics, conduction of the study in the erect or sitting position would be more desirable since a large portion of human existence is spent in these positions. A vertically open MRI system makes this possible. In this article, the postural difference in diaphragmatic motion between the sitting and supine positions in healthy subjects was investigated using a vertically open MR system. Conclusion MATERALS AND METHODS SubjectsA total of 10 healthy male volunteers participated in this study. The mean age of the subjects was 30 years (range ϭ 25-43 years), mean weight was 73.9 kg (range ϭ 63-82 kg), and mean body mass index was 24.1 kg/m 2 (range ϭ 20.6 -28.3 kg/m 2 ). All subjects were nonsmokers without any pulmonary abnormalities. They were informed of the purpose of this study and details of the methods prior to giving written consent. Approval for this study was granted by our institutional review board.

Stabilizing function of the diaphragm: dynamic MRI and synchronized spirometric assessment

“…The observed contributions of particular points (points B, C, and D) to the resultant diaphragm motion (Tables 2 and 4) provide additional, most statistically stringent support for this proposition. The theory of nonuniform recruitment of costal and crural portions of the diaphragm (24) has been previously investigated and reconfirmed (8,23,33,34). The idea that the diaphragm is a functionally dual system where costal and crural portions function mechanically in serial mode, but ventilatory (pneumatically) in parallel mode is confirmed in this study, too.…”

“…Similar to Suga et al (33) we could not detect the previously reported finding of asymmetric excursions between hemidiaphragms (8,34,36).…”

“…We agree DEs alone are not sufficient to understand all mechanical actions of the rib cage and related musculature including the diaphragm in terms of the multibody mechanical system theory (16). We have also limited the DE measurements to three points, which is similar to other authors and was sufficient for our study (34). We did not replicate the finding of Gierada's (8) proposed "saddle shape" of the diaphragm during inspiration; nor did we detect "an upper rib cage paradox" demonstrated by coordinated contraction of the upper rib cage and diaphragm muscles (4).…”

“…First, ideally, the entire rib cage including the whole range of DEs should be imaged. Due to the limited size of FOV (34) an isolated analysis of diaphragm was performed focusing on excursion. We agree DEs alone are not sufficient to understand all mechanical actions of the rib cage and related musculature including the diaphragm in terms of the multibody mechanical system theory (16).…”

Postural Function of the Diaphragm in Persons With and Without Chronic Low Back Pain

“…Only an isolated analysis of the diaphragm was performed, which focused on the diaphragm excursions, due to the limited size of the field of view. 36 Although we have limited the diaphragm excursion measurements to 3 points, this is similar to studies conducted by other authors 36 and can be considered sufficient for this type of study. In addition, the diaphragm excursions alone may not be sufficient to understand all mechanical actions of the rib cage and related musculature.…”