Indications

All trauma patients in whom a chest x-ray is indicated or a FAST exam is performed
Clinical suspicion of pleural effusion
During systematic assessment of lungs with PoCUS in dyspneic patient

Equipment

Select the appropriate probe for the patient size
Position the patient: sitting preferred over supine
Place the probe longitudinally in the posterior axillary line at the level of the xiphoid and fan as posteriorly as possible to identify the vertebral bodies and dependent fluid in the supine patient
Center the diaphragm in the screen
Identify the diaphragm, liver (or spleen on the left), lung and vertebrae
Look for normal artifacts and abnormal findings
Repeat on opposite side

Figure 1: Probe Position

Consider patient size when selecting a probe
Lift the ipsilateral arm to open rib spaces
In the supine patient ensure you place and angle the US as posterior as possible to visualize dependent fluid
If having trouble visualizing the diaphragm first move the probe cephalad/caudal followed by anterior/posterior on the chest to optimize the image
A posterior approach with the probe in the mid-scapular line can also be used: the landmarks remain the same with the exception of the vertebrae which are not visualized—this approach can be useful in fearful children who prefer to remain seated in their parents lap and hug their parents exposing their back to the examiner