Radial Artery Vasodilation With Distal Topical Heat Study

The study will be designed to detect a significant increase in the radial artery diameter of healthy volunteers after the application of a warm heat pack in the palmar aspect of the hand compared to a control group without heat applied to the hand. Employees and students at OHSU will be considered for enrollment as volunteers for this minimal risk study. Informed consent will be obtained from healthy volunteers prior to enrollment. After enrollment, the healthy volunteers will be randomly assigned in a 2:1 ratio to the heat group (Group 1) or the control group (Group 2), respectively. A brief medical history will be obtained from all volunteers, including age, sex, medications, prior interventions, prior surgeries, previous medical diagnoses, allergies, and any history of prior transradial procedures. For protection of confidential health information, brief medical history will be obtained in a private area. The volunteers will then be seated and the left hand placed supinated in a comfortable position on a table. A limited ultrasound of the left radial artery will be performed using grayscale ultrasound. A skin mark will be made with a marker to identify the measurement site. All volunteers will then be given a commercially available warm heat pack and asked to hold gently in their left hand. For the control group (Group 2), the warm heat pack will not be activated. For the heat group (Group 1), the warm heat back will be activated prior to placing in the volunteer's hand. Two investigators will be present. One investigator will be measuring radial artery diameter and will not be aware if the heat pack is activated. The second investigator will be aware of the volunteer's randomly assigned group and will activate the heat pack for the volunteer if they are assigned to Group 1. Over a period of 20 minutes, repeat ultrasound of the left radial artery will be performed in 5 minute intervals.