Normative Arm and Calf Blood Pressure Values in the Newborn

Abstract

Indirect BP measurement was obtained in the right upper arm in 219 healthy newborn infants with the Dinamap monitor and was compared with values obtained from the calf to establish normative BP values and to help establish a diagnosis of hypertension and coarctation of the aorta in the newborn. There were 174 Mexican-Americans (79.5%), 33 whites (15.0%), and 12 blacks (5.5%). The width of the BP cuff was selected to be 0.4 to 0.5 times the circumference of the extremities. Three supine position readings of BPs and heart rate were obtained from each site and were averaged for statistical analyses. Mean arm BP values (±SD) of the neonate less than 36 hours of age were 62.6±6.9/38.9± 5.7 mm Hg (48.0±6.2 mm Hg). Neonates older than 36 hours had slightly but significantly (P<.05) greater values (4 to 6 mm Hg) than did infants younger than 36 hours of age. Active neonates had values 6 to 10 mm Hg greater than quiet neonates (P<.05). BP values in the calf obtained with the same-sized cuff were almost identical with those obtained from the arm. Differences in consecutively obtained arm and calf BPs (arm values minus calf values) were 1.1±7.7 mm Hg systolic, -0.01 ± 6.2 mm Hg diastolic, and 0.9 ±6.9 mm Hg mean pressures. Mean heart rate (±SD) of neonates less than 36 hours of age was 129.4± 13.2 beats per minute and that of neonates older than 36 hours of age was 139.4± 14.1 beats per minute. These results show the following: (1) arm BPs and calf BPs using the same-sized cuff are almost identical with mean values of approximately 65/ 41 mm Hg (50 mm Hg) in neonates one to three days of age, (2) arm BP of 75/49 mm Hg (59 mm Hg) or greater is in the hypertensive range, and (3) calf BPs that are less than arm BPs by mean + 1 SD (6 to 9 mm Hg) necessitate a thorough investigation for coarctation of the aorta.