In order to determine if umbilical arterial catheter position affects the incidence of necrotizing enterocolitis, clinical outcome was analysed in 308 infants whose umbilical arterial catheter had been randomly allocated to a high (n = 162) or a low (n = 146) position. Necrotizing enterocolitis was classified as suspected or confirmed; all renal, lower limb and local catheter complications were also recorded. High umbilical arterial catheters were in place for longer than low catheters, provided more samples and were removed as an emergency less often. Lower limb blanching and cyanosis were more common with low catheters. Eleven cases of confirmed necrotizing enterocolitis occurred in the "high" group and nine in the "low" group. One case of fatal aortic thrombosis was encountered in the high group. Positioning umbilical arterial catheters in a high position allowed longer functional use and did not increase the incidence of necrotizing enterocolitis.
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.
