Patient positioning can vary according to the setting in which lung ultrasound is performed. In well patients, the sitting position can be used. This allows for easy access to the front and back of the chest. Scanning the lungs in the critical care setting may be more dfficult and the practitioner should modify their technique to accommodate patient position, presence of drains and other ICU equipment. Torso rotation and ipsilateral arm abduction can be used to access the posterior chest in supine patients.
When suspecting a pneumothorax, the supine or semi recumbent position should be used. The anterior zones should be scanned first, gradually sliding the scanner over the chest to the lateral and posterior zones. This is because air will rise anteriorly. Any pneumothorax, especially small ones will be likely seen in the anterior chest zones of a supine patient.
The semi recumbent or supine position can be used when looking for interstitial syndrome and consolidation. The same applies to pleural effusions. Pleural effusions are best seen in the lateral and posterior zones of the chest in supine patients. This is because fluid falls to the lower chest zones under gravitational pull.
Summary – Patient Position
Sitting Position
In well patients, the sitting position can be used. In sicker patients, a semi-recumbent or supine position may be necessary.
Air
Suspect a pneumothorax – scan the anterior chest in the supine or semi recumbent position. Air moves upwards.
Fluid
Suspect a pleural effusion – scan the bases of the lungs in the sitting or semi recumbent position. Fluid moves downwards under gravity.