Body Position Affects Ultrasonographic Measurement of Diaphragm Contractility

Abstract

Purpose:(1) Determine whether ultrasonography can detect differences in diaphragm contractility between body positions. (2) Perform reliability analysis of diaphragm thickness measurements in each test condition.Methods:We used a repeated-measures experimental design with 45 healthy adults where 3 B-mode ultrasound images were collected at peak-inspiration and end-expiration in supine, sitting, and standing. Mean diaphragm thickening fractions were calculated for each test position. Statistical significance was tested using 1-way repeated-measures analysis of variance with planned comparisons. For reliability analysis, the intraclass correlation coefficient (3, 3) was calculated.Results:Mean diaphragm thickening fraction increased from 60.2% (95% confidence interval [CI] 53.0%, 67.9%) in supine, to 96.5% (95% CI 83.2%, 109.9%) while seated and to 173.8% (95% CI 150.5%, 197.1%) while standing. Body position was a significant factor overall (P < .001), as were comparisons between each individual position (P < .001). Intraobserver reliability was excellent (>0.93) for all body positions tested.Conclusions:Ultrasound imaging detected positional differences in diaphragm contractility. The effect of gravitational loading on diaphragm length-tension, and body position-mediated changes in intra-abdominal pressure may explain the differences found. Future research should address methodological concerns and apply this method to patients participating in early mobilization programs in the intensive care unit.

Possible Role of Chest Ultrasonography for the Evaluation of Peripheral Fibrotic Pulmonary Changes in Patients Affected by Idiopathic Pulmonary Fibrosis—Pilot Case Series

“…Thus, the cutaneous landmark positioned would indicate pleural plane in a point very different from that evaluated by ultrasound, when the patient assumes a supine position for HRCT scans. It is known that changing posture, the position of the diaphragm, motility and lung volumes dramatically change as well [27][28][29][30]. Also, the position of arms affects diaphragm height, and consequently the position of the lung [31].…”

European Respiratory Society statement on thoracic ultrasound

“…Low TF was a good predictor of weaning outcome with consistency across studies, and higher dOR suggests that TF has better diagnostic accuracy than DE. Both TF and DE are reproducible [196,198,[200][201][202][203][204]. However, in a large multicentre randomised controlled trial by VIVIER et al [205], diaphragmatic dysfunction identified by TUS was not associated with an increased risk of extubation failure.…”

Diaphragm sniff ultrasound: Normal values, relationship with sniff nasal pressure and accuracy for predicting respiratory involvement in patients with neuromuscular disorders

“…Moreover, patient position may affect respiratory function tests [28]. Here, with US, patients were in a semirecumbent position (45°) that would amplify diaphragm dysfunction and US measurements [27, 29]. The supine position is preferred, because there is less overall variability, less side-to-side variability, and greater reproducibility.…”

“…The supine position also exaggerates any paradoxical movement and limits any compensatory active expiration by the anterior abdominal wall, which may mask paralysis [4]. According to Brown et al [29], intraobserver reliability was excellent (>0.93) for all body positions tested. Because many of our patients were not able to maintain the strict supine position for different reasons (e.g., tolerability), we systematically used the semirecumbent position (45°).…”