The absence of sonographic lung sliding after central venous catheterization would imply the presence of which procedural complication?
Answer: Pneumothorax. The rate of pneumothoraces, and other post-procedural mechanical complications of central venous access, has been decreased dramatically by the routine use of ultrasound when cannulating central veins. Use of the subclavian vein has a higher rate of post-procedural pneumothorax than internal jugular venous cannulation. Other factors associated with post-procedural complications include abnormal local anatomy (e.g. clavicular fracture) and lack of operator experience. Sonography of a normal lung will reveal lung sliding, the characteristic to-and-fro motion of the pleura with respiration, and "A-lines," which imply the presence of (in the presence of lung sliding) aerated lung. Loss of lung sliding has a broad differential, but when lost after subclavian or internal jugular vascular access should imply the presence of a pneumothorax.
Cine-loop 1: Two vessels deep to the sternocleidomastoid identified at the lateral neck; larger, thin walled, superficial vessel which is compressible with light probe pressure and subtly varies with respiration represents the internal jugular vein. The deeper, thicker walled vessel with a characteristic pulsation, no respiratory variation, and higher resistance to collapse represents the common carotid artery.
Image 1: skin and subcutaneous tissue (SQ), sternocleidomastoid (SCM), internal jugular vein (IJV), common carotid artery (CCA)
Cine-loop 2: begins with initial needle insertion, visible when through the skin and subcutaneous tissue, and in the body of the SCM, demonstrating acoustic shadowing characteristic of the needle shaft. Enters internal jugular vein and secured in the mid-lumen.
Image 2: echogenic needle shaft (red circle) casts a characteristic acoustic shadow (parallel white lines)
Image 3: the needle tip (red circle) is located prior to puncture of the anterior wall of the internal jugular vein.
Cine-loop 3: right hemithorax, third intercostal space. + lung sliding, no pneumothorax.
Cine-loop 4: left hemithorax, third intercostal space. + lung sliding, no pneumothorax.