Effect of Combination of Subcutaneous Lidocaine With Two Different Doses of Nitroglycerin Versus Subcutaneous Lidocaine Alone for Ultrasound-guided Radial Artery Cannulation: A Randomized Controlled Trial.

Objective(s): To estimate the first-attempt and overall-attempt success rates of radial artery cannulation and to compare the diameters and cross-sectional area (CSA) of the radial artery before and 5 minutes after subcutaneous administration of different doses of nitroglycerin with lidocaine.

Design: A double-blinded, randomized controlled study.

Setting: A single-center study conducted in a tertiary care hospital.

Participants: All adult patients aged 18 to 70 years of either sex belonging to American Society of Anesthesiologists physical status classes I, II, or III.

Interventions: Group C: 0.25 mL of 2% lidocaine + 0.25 mL of normal saline Group T1: 0.25 mL of 2% lidocaine + 0.25 mL of nitroglycerin 250 μg. Group T2: 0.25 mL of 2% lidocaine + 0.25 mL of nitroglycerin 500 μg.

Measurements and main results: The nitroglycerin groups (500 μg and 250 μg) had higher first-attempt success rates (77.1% and 82.6%) compared with the lidocaine group at 51.1% (p = 0.002, chi-square: 12.61). This could be because the subcutaneous nitroglycerin injection increased the CSA of the radial artery greater than lidocaine (7.13 ± 4.41 mm² and 5.81 ± 4.69 mm²v 1.33 ± 3.93 mm²; analysis of variance F = 25.4, p < 0.001).

Conclusions: Subcutaneous infiltration of nitroglycerin before cannulation improved the first-attempt success rate in adult patients and a comparable overall attempt success rate was obtained even with lower doses of nitroglycerin. There was an increase in the diameters of the radial artery, which would have improved the success rate.