The first purpose of this study is to see how blood pressures taken at different sites, specifically the forearm, upper arm and heart vessels, are different. The second purpose is to see if body structures such as vessel size and depth, size of the arm, and amount of tissue in the arm influence differences in blood pressures taken at these sites. The third purpose is to develop a mathematical model of the waves generated by the arm arteries (brachial and radial) to predict differences in forearm and upper arm blood pressures. The results of the study may be used to design more accurate non-invasive blood pressure monitors for the forearm site.

Accurate blood pressure (BP) measurement is required to provide appropriate healthcare. Inaccurate BPs may lead to under and/or over-treatment of health conditions and medical diseases such as hypertension. Blood pressure (BP) measurement using automatic, non-invasive oscillometric monitors is common in clinics, physicians'offices and hospital settings. The brachial (upper arm) site is the gold standard for non-invasive BPs. However, in some situations, this site is inaccessible due to injury, surgery, dialysis shunts, intravenous devices, and lymphedema. When the upper arm is difficult to access or the available BP cuffs do not fit an individual's arm, the forearm site is often the preferable alternative. The increased incidence of obesity nationally also contributes to the heightened use of forearm BPs. Questions remain concerning the accuracy of forearm non-invasive BP measurements. Although most researchers report that upper arm and forearm readings are not interchangeable, size of differences vary for individuals and factors influencing differences in readings have not been thoroughly investigated.

Inclusion Criteria:

• 18 years of age
• able to speak and write in English

Exclusion Criteria:

• Individuals with non-intact skin where the BP cuffs would be placed
• Individuals with injury or surgery to the arm within the last month
• Individuals with lymphedema in the limb selected for measurements
• Individuals with arteriovenous fistulas
• Individuals with differences > 5 mm Hg between right and left arm oscillometric systolic BP measurements
• Individuals with documented valvular disease
• Individuals with atrial fibrillation or atrial flutter (as recommended by BP device manufacturers due to device inaccuracy)
• Individuals with an International Normalized Ratio (INR) > 1.7
• Individuals with intravenous catheters in both arms
• Individuals who require immediate cardiac surgery or unanticipated emergency treatment or who are unstable during the procedure

patients undergoing non-emergent cardiac catheterization