Diaphragmatic ultrasound: Technique and cases

Sarah Hamilton1, Sowkhya Ramachandraiah1, Richard Riordan2, Catherine Gutteridge2, 1Imaging Peninsula Radiology Academy, 2Imaging Plymouth Hospitals NHS Trust

Diaphragmatic dysfunction is commonly underdiagnosed as a consequence of the non-specific nature of presentation. Symptoms include dyspnoea, asymmetric breathing, paradoxical movement of the epigastrium, recurrent pneumonia or unilateral collapse, and in mechanically ventilated patients slow respiratory weaning.

Diaphragmatic paralysis can be caused by direct involvement of the diaphragm (through trauma, surgery or adjacent pathology), or through neuromuscular disorders such as direct phrenic nerve damage, motor neurone disease, central nervous system abnormalities and muscular dystrophies. Prompt diagnosis is important because some causes are amenable to treatment and provision can be made for longer term ventilatory support.

There are multiple well-described techniques for evaluation of the diaphragm, including many different modalities and indirect function tests such as pulmonary function tests, trans diaphragmatic pressure measurements, phrenic nerve conductions studies and electromyography. Although each of these has their strengths and weaknesses, ultrasound combines many of the strengths, offering assessment of both structure and function in a non- invasive, real time manner at a location of choice (bedside or ultrasound room).

We present a guide to the technique of ultrasound assessment of the diaphragm and a series of clinical cases illustrating its utility.

Although not a new technique, diaphragmatic ultrasound currently lies outwith the skill set of many experienced sonographers and radiologists, commonly falling to critical care or respiratory physicians. At a time when clinicians are looking for added value we suggest that diaphragmatic ultrasound is a useful skill to retain within the imaging department.

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