Diaphragmatic Ultrasound in Adults: Image Acquisition and Interpretation

Summary

Point-of-care ultrasound (POCUS) is an essential technique for screening for diaphragmatic dysfunction due to its portability, non-invasiveness, and real-time imaging capabilities. Although current diaphragmatic POCUS protocols exist, they suffer from poor interoperator reliability and lack consensus guidelines. Here we describe a technique that is reproducible and simple to perform.

Abstract

Diaphragm dysfunction is a widely recognized concern across numerous medical specialties and clinical settings. Timely and accurate assessment of the diaphragm is vital not only in critically ill patients, where it has a role in weaning from mechanical ventilation and respiratory outcomes, but also in the perioperative arena as a diagnostic tool to detect phrenic nerve function. Diaphragmatic assessment has traditionally utilized fluoroscopy and nerve studies that are time-consuming, costly, and non-portable. Point-of-care ultrasound (POCUS) overcomes these barriers and can be used as a tool for non-invasive screening of diaphragm function. However, POCUS for diaphragmatic dysfunction currently suffers from several issues such as a lack of consensus guidelines, a multiplicity of protocols, and poor interoperator reliability among existing protocols, most notably with the assessment of dome of diaphragm excursion and diaphragmatic thickening. To address these issues, this manuscript reviews the available literature on diaphragmatic POCUS and identifies an image acquisition technique that is both simple to perform and has high interoperator reliability. This technique first describes a qualitative evaluation of diaphragm excursion, followed by a quantitative assessment of the excursion of the zone of apposition. The technique is described stepwise along with all the following: patient positioning, transducer selection, probe placement, image optimization, and interpretation.

Introduction

Diagnostic ultrasound can be separated into two divisions: consultative and point-of-care. Consultative ultrasound incorporates an exam performed by a distinct specialist team, whereas POCUS is both performed and interpreted by the clinician caring for the patient in real time¹.

Over the past few decades, diagnostic POCUS has emerged as a transformative tool in modern medicine, with applications rapidly expanding across specialties. These POCUS applications are driven by ultrasound's noninvasive nature, portability, and real-time imaging capabilities. Further, within diagnostic POCUS, the applications that have a....

Protocol

All procedures performed in studies involving human participants were in accordance with the ethical standards of the Duke University Health System institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all participants. Supplemental File 1 contains the most important still images from each video.

1. Phase 1: Qualitative assessment of diaphragmatic excursion (Vis.......

Discussion

POCUS offers clear advantages for diaphragmatic assessment, including portability, non-invasiveness and real-time imaging capabilities. These strengths can be taken advantage of with this feasible and accessible protocol and can be applied in a variety of clinical settings. This protocol begins with a qualitative assessment of diaphragmatic excursion to answer the question of whether gross hemi-diaphragmatic dysfunction is present. If the answer is unclear or if more specific information is needed, the second step of the.......

Materials

Name	Company	Catalog Number	Comments
Medical Ruler	MediChoice	NA	We used Medichoice as that is what is readily available at our institution and it comes with the skin marker, however any medical ruler will work. The majority of skin markers come with a type of ruler or measurement system, but if not a separate ruler can be used.
Skin Marker	MediChoice	NA	We again used Medichoice as that is what is readily available at our institution and it comes with the ruler, however any standard skin marker will work.
Ultrasound Gel	Aquasonic	NA	Any standard gel will work. Sterile packs are not necessary but can be used on a case-by-case basis at the providers discretion.
Ultrasound Machine	Samsung and GE	NA	Any standard portable ultrasound machine will suffice.