Evaluation of the effect of Topcial Glyceryl Trinitrate on radial artery diameter for catheterisation in newborns: a randomised controlled trial

Children admitted to intensive care units require arterial cannulation for monitoring and blood sampling. In neonates, arterial access can be achieved through umbilical artery catheterization in the first 3-4 days, whereas in older infants and children it is via peripheral arteries. Even in neonates, umbilical arterial catheterization may not be feasible (e.g., abdominal surgical conditions). The radial, posterior tibial, and brachial arteries are commonly used for cannulation in children and neonates. The radial artery cannulation is also being increasingly used for percutaneous cardiac procedures. These arteries are of small calibre, which makes their localization and cannulation challenging and potentially unsuccessful. The radial artery is the most frequently used site for cannulation as it is superficial and has a relatively larger diameter compared to other peripheral arteries. Repeated attempts can lead to bleeding, spasm and dissection of the peripheral arteries. Ultrasound-guided insertion can increase cannulation success but requires high expertise. A recent paediatric audit found that even with ultrasound, the first attempt success rate was only 31%. Resource-limited settings may be limited by the expense of the ultrasound equipment and maintenance. Therefore, increasing the internal diameter and preventing vasospasm are important for successful peripheral arterial cannulation in neonates. Glyceryl trinitrate (GTN) has the potential to increase cannulation success in children by increasing the diameter of peripheral arteries and preventing vasospasm when used as a local application. We hypothesize that local application of GTN in the form of a transdermal patch will achieve adequate dilatation of the radial artery in neonates. We aim to conduct a randomised controlled trial to establish effectiveness and safety of local GTN in increasing the diameter of the radial artery in neonates.