Radial Artery Vasodilation With Distal Topical Heat Study
Phase: PHASE1
Conditions: Radial Artery
Sponsor: Oregon Health and Science University

Title: Radial Artery Vasodilation Heat Study 
 
NCT: NCT03620383 
 
Date: 8/27/2019 
 
 

Study Protocol: 
 
Study subjects 
Institutional review board (IRB) approval will be obtained for this prospective, randomized, 
single-blinded controlled clinical trial (NCT03620383). Study subjects will be recruited from 
among healthy healthcare workers with no currently active vascular or chronic disease. 
Exclusion criteria include prior history of left radial artery access. Study design and purpose 
were explained to the subjects prior to enrollment and written informed consent will be obtained.  
 
Randomization 
The census of the subjects will be enrolled in the study on a first-come-first-serve basis. The 
subjects will be randomized into palmar warming (“PaW”) and control groups based on a draw 
from a pool of paper slips with a group assignment written on them. The draw will be conducted 
without replacement from a pool of 60 slips equally divided into heat and no heat groups. To 
avoid violation of randomization, the study is designed to stop when one group reaches to its 
maximum predicted number.  
Blinding 
The sonographer will be unaware of the group assignment of the subjects. Also, to prevent 
sensing the temperature of the palmar pad, the sonographer will hold the probe from its 
proximal-most point and avoided contact or proximity with the subjects’ hand. 
Intervention 
The PaW group will be given a warm commercially available air-activated heat pack (Kobayashi 
Consumer Products LLC, Dalton, GA) to hold in the left hand for palmar warming. The control 
group will be given a de-activated version of the same heat pack to hold. 

Radial artery cross-sectional area (CSA) measurement 
Participants will be placed in a sitting position with their left forearm resting on a table. Before 
given the activated or de-activated heat pack, baseline left radial artery intraluminal height and 
width will be measured 2 cm proximal to the styloid process using an L20-5 linear array 
transducer with a ZS3 ultrasound system (Mindray Medical Systems, Inc, Mountain View, CA). 
A skin mark will be made at the site of measurement to ensure consistency in measurement 
location. The PaW group will then be given the activated heat pack and the control group will be 
given a de-activated heat pack. After 5 minutes of holding their respective heat packs, repeat left 
radial artery intraluminal height and width measurements will be obtained in both groups at the 
same location of the baseline measurement as indicated by the skin mark. Repeat height and 
width measurements will be again obtained after 10, 15, and 20-minutes of holding the assigned 
heat packs in both groups. Cross-sectional area (CSA) will be calculated according to the area for 
an ellipse based on height and width measurements. All sonographic measurements will 
performed by a single board-certified radiologist with two years of experience.