CICM SAQ 2015.2 Q15

a) Describe the ultrasound features that help differentiate the internal jugular vein and the carotid artery? (70% marks)

The IJ vein:

• Has an elliptical shape
• Is larger
• More collapsible with modest external surface pressure than the carotid artery (CA), which has
  rounder shape, thicker wall, and smaller diameter
• A Valsalva manoeuvre will further augment their diameter
• The IJ vein diameter varies depending on the position and fluid status of the patient and is
  particularly useful in hypovolemic patients.
• Adding Doppler, if available, can further distinguish whether the vessel is a vein or an artery. Colour
  flow Doppler demonstrates pulsatile blood flow in an artery in either SAX or LAX orientation.
• A lower Nyquist scale is typically required to image lower velocity venous blood flows. At these reduced settings, venous blood flow is uniform in colour and present during systole and diastole with laminar flow, whereas arterial blood flow will alias and be detected predominantly during systole
  (Figure 5) in patients with unidirectional arterial flow (absence of aortic regurgitation).
• A small pulsed-wave Doppler sample volume within the vessel lumen displays a characteristic
• Veins are thin walled and compressible and may have respiratory-related changes in diameter. In
  contrast, arteries are thicker walled, not readily compressed by external pressure applied with the ultrasound probe and pulsatile during normal cardiac physiologic conditions.

b) List the complications of central line insertion. (30% marks)

• Pneumothorax
• Air embolus
• Haematoma
• Haemorrhage
• Thrombosis
• Stenosis
• Arterial puncture / catheterisation
• Incorrect catheter tip position
• Central vein perforation
• Tamponade
• Cardiac arrhythmia
• Embolised, fractured or irretrievable guide wires
• Infection