The Reliability of Evaluation of Diaphragm Thickness With Ultrasound Imaging by Co-Medical Staff

Abstract

Background: Evaluation of diaphragm thickness by ultrasound imaging is currently being used in the clinical setting. These uses include evaluating diaphragm dysfunction during management of mechanical ventilation and as an important criteria for weaning patients from mechanical ventilation. However, the education for the method of using ultrasound imaging for co-medical staff is not common. Furthermore, there is no published research describing the reliability of ultrasound evaluation by co-medical staff, who are not radiologists or sonographers. Therefore, the purpose of this research is to investigate the reliability of diaphragm thickness measurement with ultrasound imaging by co-medical staff after training in the use of the device. Methods: This study was approved by the IRB at Yokosuka General Hospital UWAMACHI. Three co-medical staff (RRT/RPT, RPT, Medical technologist) were trained in the use of ultrasound imaging for two months. The data were gathered from December 2018 – May 2019. The diaphragm thickness was evaluated in twenty healthy male subjects under resting conditions. A device (TUS-X200S, TOSHIBA) was used in all measurements. As per previously published research, the subjects were supine, with the right shoulder in 30 - 40 degree abduction. The measurement point was marked at 8th to 10th intercostal margin on the right anterior axillary line, allowing the diaphragm to be visualized at FRC and at TLC. A linear probe in the B mode was used. A printout of the graphic image of the ultrasound display was used for the measurement. The thickness of the diaphragm, 5 mm and 10 mm from the edge of the graphic display of the ultrasound image at FRC was evaluated, as well as the point where the pleura and peritoneum could be identified, in parallel, at TLC. Three examiners evaluated diaphragm thickness twice at FRC and TLC. Intraclass Correlation Coefficients (ICC (2, 1)) were analyzed by R (ver. 3.4.1). Results: Each ICC (2, 1) for the first and second measurements were: FRC 5 mm, 0.92 and 0.93, respectively; FRC 10 mm, 0.89 and 0.93, respectively; TLC, 0.86 and 0.85, respectively. Conclusions: The findings suggest that measuring diaphragm thickness at FRC and TLC, by well-trained co-medical staff, is reliable and effective. A limitation of this study is that the thickness of the diaphragm may be different, if the measurement point on the body surface for each evaluation is not marked and used consistently among different examiners. Disclosures: None.