The ankle-brachial index in normal neonates and infants is significantly lower than in older children and adults.

UNLABELLED: Vascular trauma from accidental or iatrogenic causes is becoming more common in children. In early infancy, the most common arterial injuries are caused by diagnostic or interventional cardiac catheterizations. Doppler arterial pressure measurements and the computed ankle-brachial pressure index (ABI) are the most helpful diagnostic modalities in the assessment and follow-up of the ischemic extremity. Because normative ABI data in small children are not available, an ABI of 0.9 or less (based on data obtained from an adult population), is used to indicate limb ischemia in young infants. The purpose of this study was to define the normal values of ABI in newborns and infants.

MATERIALS AND METHODS: Three hundred and fifty patients were divided into two groups: group 1 (n = 200; male-to-female ratio, 1:1) were full-term (gestational age 40 +/- 1.3 weeks, surface area 0.22 +/- 0.02 m2) healthy newborns following uneventful pregnancy and delivery. Group 2 (n = 150) were healthy patients aged 2 weeks to 2.5 years admitted for elective hernia repair. All the patients underwent a complete physical examination, which excluded any cardiovascular pathology. The systolic blood pressure (BP) was measured bilaterally over the brachial, tibialis posterior, and dorsalis pedis arteries. All BP data were obtained in the supine position, using an ultrasonic Doppler flow detector, an appropriately-sized pneumatic cuff and a sphygmomanometer. The chosen cuff size was long enough to completely encircle the circumference and wide enough to cover 75% of the length of the upper arm. The same cuff was applied around the ankle above the malleoli. BP values were expressed as mean +/- SD in mm Hg. If there was a difference between the BP in the two arms, the higher pressure was used for calculation of the ABI.

RESULTS: The BP measurements in newborns (group 1) were left brachial, 98 +/- 11; right brachial, 90 +/- 10 (P < .001), left and right tibialis posterior and left and right dorsalis pedis were 83, 81, 84, and 82 mm Hg, respectively. The mean computed ABI was 0.88 +/- 0.11. Fifty eight percent of the newborns had an ABI less than 0.9 (lower limit of normal in adults). The ABI values in patients belonging to group 2 increased with age and surface area. The mean ABI was 1.0, 1.1, and more than 1.1 in patients aged, 1, 1.5, and 2 years with surface areas of 0.4, 0.5 and 0.6 m2, respectively (P < .001 compared with group 1).

CONCLUSION: The normative ABI in newborns and infants is significantly lower than in older children and reaches normal (adult) values during the second year of life. These data may be used as a reference when assessing lower extremity ischemia caused by trauma in young patients.