We read with interest the recent correspondence1 regarding the use of ultrasound to aid cannulation of the impalpable radial artery in the forearm and agree that this is a valuable technique in a variety of clinical scenarios. In a randomized, prospective study of 60 adults, Shiver et al.2 demonstrated that the use of ultrasound significantly reduced both the time taken for radial arterial cannulation (P = 0.0004) and the number of attempts required (P = 0.001). In children, however, ultrasound appears not to offer the same advantages. In a randomized, prospective study of 151 paediatric patients requiring radial artery cannulation, Ganesh et al.3 found no differences in time to successful cannulation, total number of attempts, number of successful cannulations during the first attempt, or in the number of cannulae used for catheterization.
In addition to facilitating cannulation of anatomically aberrant vessels, ultrasound is particularly useful when arterial pulsation is weak or absent. In patients maintained on nonpulsatile cardiopulmonary bypass or axial flow ventricular assist devices, cannulation using the palpation method is rendered virtually impossible. In our experience, the use of ultrasound in these settings – to guide cannulation and avoid inadvertent cannulation of nearby veins – is essential.
1 Gratix AP, Atkinson JD, Bodenham AR. Cannulation of the impalpable section of the radial artery: preliminary clinical and ultrasound observations. Eur J Anaesthesiol 2009; 10:887–889.
2 Shiver S, Blaivas M, Lyon M. A prospective comparison of ultrasound-guided and blindly placed radial arterial catheters. Acad Emerg Med 2006; 13:1275–1279.
3 Ganesh A, Kaye R, Cahill AM, et al
. Evaluation of ultrasound-guided radial artery cannulation in children. Pediatr Crit Care Med 2009; 10:45–48.