Novel Measurement Methodology for Diaphragm Ultrasound

Ultrasound has become a widely used tool on the Intensive Care Unit over the last decade. It's areas for application have since then expanded now also including imaging of the diaphragm and other respiratory muscles to for example, detect patient ventilator asynchrony, quantify its function and predict the outcome of extubation. However, the standard view for detecting diaphragm excursion (subcostal view) is often blocked by air in the stomach and/or intestines. For this reason, an alternative method to visualise excursion would be of interest. In this regard, the PLAPS-point (posters lateral alveolar and pleural syndrome point) presents itself as feasible alternative, given that the liver and spleen serve as acoustic windows to visualise the diaphragm and that it is already a standard point of evaluation for pulmonary pathology. We hypothesise that measurements from the PLAPS will be more feasible than from the subcostal view and yield a good ICC (> 0.8).

Measurements:
Two ultrasound devices will be used simultaneously to directly compare measurements made in the different measurement sites (subcostal and PLAPS). The subcostal excursion will be recorded in M-mode on midclavicular line as closely aligned to the movement of the dome as possible. The excursion in the PLAPS will be recorded in B-mode at the site of maximal excursion.

In order to test various clinical situations, measurements will be done during quiet breathing, short nasal breathing (sniffing) and deep breathing. The measurements will be repeated on both sides of the body.

This results in a total of 288 images (12 participants x2 transducers x2 sides x3 breathing patterns)

Diaphragm excursion measured from the PLAPS point is more feasible than from the subcostal view and yields comparable results of excursion

Measurements will be performed using a Philips CX 50 machine and a Sonosite Edge II machine. Measurements will be taken once the volunteer is instructed and has performed the various breathing patterns.

Ultrasound examination from the PLAPS and subcostal view