The Use of Bedside Ultrasound

LSU Physician Champion - Dr. Seema R. Walvekar

Bedside Ultrasound - Lung Sliding

Absence of lung sliding," is strongly suggestive of pneumothorax but does not Rule in Pneumothorax !! Lung sliding may be absent in the following conditions –
Main stem intubation
Main stem occlusion
Inflammatory changes to the pleura
Pleural sequelae from pleurodesis

Evaluation for sliding lung is very useful in the acutely dyspneic patient, decompensated ventilator patients, and for ruling out post-procedure pneumothorax
If there were air between them, as is the case with pneumothorax, the deeper visceral pleural line CANNOT be "seen" (because air that is now in the pleural space will reflect the ultrasound waves back to the transducer, and not allow the wave to reach the visceral pleura - i.e. the "moving" pleura which normally produces this shimmering or sliding)

In Pneumothorax One sees the static parietal pleura and so the pleural line will lack this "shimmering" or "sliding

'A' Lines

- Air reflects ultrasounds entirely as a mirror does with light
- The A line artefact is the horizontal, repetitive, reverberation artifacts that originate from the pleural line
- Seen in normal lungs or in pneumothorax
- The emitted ultrasound wave is reflected multiple times by the pleural interface
- This back and forth phenomenon gives a false impression to the imaging software that the pleural interface is deeper
- Each A line is separated by a distance equivalent to the thickness of the subcutaneous tissue between the ultrasound probe and the pleural interface

Substances that replace air and transmit ultrasound waves – NO ‘A’LINES
- Interstitial /alveolar edema
- Consolidation
- Blood
- Contusion
- Tumor