Palmar Warming for Radial Artery Vasodilation to Facilitate Transradial Access: A Randomized Controlled Trial

To investigate the efficacy of palmar warming to induce radial artery vasodilation.

After informed consent was obtained, healthy volunteers (n = 45) were randomized 2:1 in palmar warming and control groups, respectively, for this prospective, randomized, single-blind clinical trial (NCT03620383). The palmar warming group was given a warm, commercially available, air-activated heat pack (Kobayashi Consumer Products LLC, Dalton, Georgia) to hold in the left hand for palmar warming. The control group was given a deactivated version of the same heat pack. Left radial artery cross-sectional area (CSA) measurements were obtained at baseline and in 5-minute intervals up to 20 minutes in both groups. Differences in the trends of changes in the radial artery CSA between palmar warming and control groups were examined with the age- and sex-adjusted repeated measure analysis of variance. Propensity score-matched treatment effect analysis was conducted to quantify the effect of heat on radial artery CSA.

The palmar warming group and the control group were significantly different in terms of subject sex (males/females: 7/23 and 10/5, respectively; P = .005) and baseline CSA (2.5±0.2 mm² vs 3.2±0.3 mm², respectively; P = .014). Radial artery CSA showed an increasing trend over time in the palmar warming group compared to a stable trend over time in the control group (P < .0001). Propensity score-matched comparison showed a 43.9% increase (95% confidence interval: 34.1%-53.8%) in CSA in the palmar warming group compared to the control group (P < .0001).

The palmar warming technique is effective at dilating the radial artery and may be a beneficial technique to facilitate transradial access.