- To RULE IN the presence of a normal lung via lung sliding
- The absence of lung sliding is not specific and cannot be used to diagnose a pneumothorax
- Place the probe in the midclavicular line with the leading edge to the patient's head.
2-5 MHz Curvilinear Probe
Can also use phase array probe.
- The lung exam focuses on the bright (hyperechoic) line immediately posterior to the ribs. This line is the parietal pleura, which is hyperechoic because of its fibrous nature. Normally the aerated lungs cannot provide an acoustic window for ultrasound, so we need to focus on artifacts to see the physiology of the lungs.
- You can identify lung sliding here by turning on Zoom, and watching the pleura during respiration.
- If you see a shimmer or (Ants on a Line Sign) this indicates lung sliding. To confirm this move on to M-Mode scanning below.
- Switch into M-mode on the ultrasound machine and use the pad to place the dotted line between the ribs
- Hit “update” or "M-mode" again to turn on M-mode.
- Save a clip with inhalation
Normal Lung: Seashore Sign
Impression and Medical Decision Making
66 yo male in the ICU. Patient was recently admitted to ICU for septic shock secondary to urosepsis. Antibiotics are started, cultures are collected and patient is appropriately resuscitated. Left subclavian line was placed for central venous access. After initially be stabilized on admission to the ICU, patient rapidly decompensates. VS: HR 130 BP 89/40 RR 35 T 100.1 Sats 88% on 6L NC. His oxygen requirements continue to increase, while his hypotension. Lung sounds are clear and normal on the right side, and absent on the left. Thoracic ultrasound on the left side shows the following:
Tips & Tricks
- Subcutaneous air mimics pleural line – can give false positive or negative for lung sliding.
- Turn Off THI (Tissue Harmonics). Lung on US is mostly artifact. Tissue Harmonics filters out artifact
- If interested in more thoracic US – read any article or book chapter by Daniel Lichtenstein