Is There A Difference Between Calf and Brachial Blood Pressures?

Monday, 18 November 2013: 10:40 AM

Nhu Nguyen Thuy Tran, RN, BSN, MSN, CCRN
Cardiothoracic surgery, Children's Hospital Los Angeles, Los Angeles, CA

Learning Objective 1: The learner will be able state whether there is a difference between calf and brachial blood pressures.

Learning Objective 2: The learner will be able to state the importance of calf blood pressure measurements.

The standard of care for noninvasive blood pressure (NIBP) measurements are from the upper arm.  However, in the neonatal intensive care units (NICU), it is common practice to take measurements from the calf.  Nurses commonly take calf NIBPs because other extremities are not available, but there is little evidence to support calf blood pressures as a reliable site for BP measurement and the evidence is conflicting.  The purpose of this study was to show no statistical difference between the calf and brachial blood pressure measurements.

This was a prospective quasi-experimental study design with IRB approval.  The subjects were a convenience sample of 52 NICU patients, ranging from 3 days to 207 days old, born at 24-40 weeks gestation.  The inclusion criteria were any neonate (preterm or term) or infant admitted to the NICU and parental consent.  Blood pressure measurements were taken according to the AHA guidelines on the upper arm and the calf.  The instrument to measure the blood pressures was the Philips oscillometer device.  The same size cuff was used for the brachial and the calf blood pressures.  Three blood pressures were taken from an upper and lower extremity, with 2 minute intervals in between each measurement.

The second and third blood pressures were used for data analysis.  The data was analyzed using a mixed ANOVA.  The p-values lower and upper limits have a 95% confidence interval for the difference.  The difference was not significant for systolic (p=0.6159) or mean BP (p=0.1298), but was significant for diastolic (p=0.0263).

The data showed no statistical difference between the systolic and mean blood pressures, but did show a difference in the diastolic blood pressures.  This study has great significance because most NICUs use the mean BP or the systolic BP for clinical decisions.  The study supports the current practice of bedside nurses.