Umbilical Venous Catheter Insertion Depth in Neonates

Overview

In this randomized clinical study, neonates who require umbilical venous catheter (UVC) insertion as part of their routine care at anytime during their NICU admission will be randomized to one of the 2 formulas for estimation of the pre-insertion UVC depth (umbilicus to the nipple in cm minus 1 (UN - 1) or birth weight based formula (\[(3× birth weight (Kg) + 9)/2+1)\]. UVC will be inserted under sterile condition as per unit protocol. To verify the UVC tip position, a thoracoabdominal radiograph will be taken. In addition, the investigators will do a ultrasound of the heart to assess the exact location of the catheter tips as soon as possible but within 6 hours of insertion.

Background: The ideal position of UVC) tip to minimize complications is just outside the heart at the junction of inferior vena cava and right atrium. UVC related complications are mainly due to catheter malposition. Accurate prediction of insertion length of UVC as well as confirmation of the position after insertion by radiograph or with ultrasound is very important to avoid complications. UVC malposition with subsequent re-positioning exposes these fragile infants to unnecessary handling, further radiologic exposure and increasing risk of infection. The commonly used formulas to estimate the depth of umbilical catheter include Dunn's shoulder to umbilical length graph and a birth weight based formula proposed by Shukla and Ferrara in 1986. In Calgary, the most commonly used method for estimation of UVC insertion length is the birth weight based formula (i.e. UVC insertion length = (3 x birth weight + 9)/2 +1). The success rate of achieving the optimum position of catheter tip using this formula ranges from 31-40%. A recent retrospective study reported the use of different surface markers for calculating UVC insertion depth. A distance from base of umbilicus to nipple distance (UN)-1 cm provided the best and most accurate insertion depth of UVC. This formula had accuracy rate of 84% compared with 57% accuracy rate with birth weight based formula. The objectives of our study are: 1. To compare accuracy rate between UVC insertion length estimated by using two formula (i.e. umbilicus to the nipple distance in cm minus 1 (UN - 1) and Shukla's birth weight based formula (\[(3× birth weight (Kg) + 9)/2+1)\] in achieving optimum UVC tip position 2. To compare the accuracy rate of UVC tip position between two methods based on growth status of neonates Methods: This is a randomized clinical study. All infants who require UVC insertion as part of their routine care at anytime during their hospital admission are eligible for the study. Infants with hydrops fetalis, abdominal wall defects, congenital diaphragmatic hernia and/or major structural heart disease will be excluded from the study. When a newborn baby needs UVC central line insertion, neonate will be randomized to one of the 2 formulas for estimation of the pre-insertion UVC depth. UVC will be inserted under sterile condition as per unit protocol. To verify the UVC tip position, a thoracoabdominal radiograph will be taken. In addition,the investigators will do a ultrasound of the the heart to assess the exact location of the catheter tips as soon as possible but within 6 hours of insertion.