Neonatal hypertension appears unrelated to aortic catheter position

In 1981 we reported severe symptomatic hypertension(HTN) in 2% of all neonatal admissions, 85% with umbilical arterial catheters(UAC) above the renal arteries. To prospectively evaluate the occurrence of HTN with respect to catheter tip position, we randomly placed high (T6-10) vs low (L3-5) UACs. This preliminary report reviews the first 182 infants analyzed. Birth weight (BW) ranged from 0.72-4.4 Kg, mean 2.0 Kg, with gestational age (GA) 24-44 wks, mean 32 wks. BP was recorded every 8 hours via the UAC (68% Orange Medical Instruments [OMI] Continuous O2 Recording Catheters, 32% Argyle Catheters) or Dinamap for a maximum of 30 days. Problems with catheter insertion occurred in 39/182(21%) without regard to catheter type: 28/124(22.6%) OMI, 11/85(18.9%) Argyle, p>.10. BP showed no diurnal variation but was related to BW, GA and postnatal age. HTN(mean arterial pressure 70 × 3 days) occurred in 19/182 (10%). In all cases HTN was asymptomatic and did not warrant treatment. Compromised perfusion to legs(unilateral cyanosis, pallor, loss of pulses) was greater with low UACs; other complications were unrelated to catheter tip position. We conclude that HTN bears no relationship to catheter position; the prevailing numerical definition over-diagnoses HTN in high risk neonates.