ESTIMATING UMBILICAL VENOUS CATHETER INSERTION DEPTH IN NEWBORNS USING BIRTH WEIGHT OR BODY MEASUREMENT: A RANDOMIZED TRIAL

Abstract

Abstract BACKGROUND Incorrectly positioned Umbilical Venous Catheters (UVC) are associated with serious complication in newborns. Accurate prediction of insertion depth, as well as confirmation of position; are important factors to avoid complications. UVC position verification by standard radiography is imprecise in comparison to ultrasound. A retrospective study reported Surface Measurement (SM: umbilicus to nipple distance in cm minus 1) was more accurate than Shukla’s Birth Weight (BW) based formula [(3× birth weight (Kg) + 9)/2 + 1)] for estimating UVC insertion depth. OBJECTIVES The primary objective is to compare the proportion of optimum UVC position (verified by ultrasound) using SM / BW based insertion depths formulas. Secondary objective is to compare the proportion of optimum UVC position between the two methods based on birth weight, and growth status of the infants. DESIGN/METHODS In this prospective randomized trial, infants undergoing UVC insertion were randomly assigned to either SM or BW based formula. Infants with hydrops, major congenital heart disease, abdominal wall defects, or congenital diaphragmatic hernia were excluded. The optimum UVC position was then verified using ultrasound in addition to the standard radiography. The primary outcome was optimum UVC position determined by ultrasound, read by an investigator blinded to the assignment. Optimum UVC tip position was defined as the catheter tip in the inferior vena cava between the hepatic vein confluence and right atrial opening. Intention to treat analysis was performed. RESULTS Of the 196 enrolled infants, 97 were assigned to SM based and 99 to BW based formula. UVC insertion was successful in 195 infants, however the catheter could not be advanced to the targeted depth in 36 infants (18 in each group). There was no difference in baseline demographic parameters. There was no difference in the primary outcome between infants assigned to SM or BW based formula (35% vs 27%, Relative risk (RR), 1.28; 95% CI 0.84 -1.95). In the subgroup analysis for ELBW (<1000g); proportion of optimum UVC position was significantly higher with SM based as compared to BW based formula [14/32 (44%) vs 6/31 (19%), p = 0.03]. Similarly, for SGA (Small for Gestational Age)/LGA (Large for Gestational Age) infants, SM based formula showed better positioning than BW based formula [8/15 (53%) vs 4/16 (25%), p = 0.10]. CONCLUSION Although no significant difference was noted in the percent of optimum UVC position using either SM or BW based formulas; SM based formula was superior in ELBW, SGA and LGA infants.