Indications for the Use of Ultrasound

The indications for the use of ultrasound in vascular access vary.

In central access (eg. internal jugular or femoral vein), ultrasound should be used at all times [5] unless time-critical intervention mandates otherwise (e.g. in cardiac arrest) [3].

Subclavian venous access is also very useful, particularly in the shocked patient or where head-down positioning is not possible, as it is less collapsible. It is possible to perform subclavian vein cannulation with ultrasound-guidance, though the vein is targeted more laterally (axillary/subclavian vein junction) as it is more easily visualised on ultrasound. Elevating the shoulder can often provide better visualisation of the vein, as the clavicle is lifted out of the way.

In peripheral access it has a use when conventional access fails. This may be in an ill patient who is shut-down, or in an intravenous drug user whose veins are damaged. In both instances the basilic vein, medial to the biceps above the elbow, is usually accessible and patent. Peripheral cannulation, whilst invasive, does not carry the risks of air embolism, bleeding and damage to other structures that jugular and femoral cannulation carries.

Ultrasound may also be used to guide arterial cannulation for invasive BP monitoring and blood gas sampling. It is particularly helpful in the shocked or arrested patient. Radial, brachial and femoral arteries are the most common sites used.