Estimating umbilical catheter insertion depth in newborns using weight or body measurement: a randomised trial

Abstract

Objective Incorrectly positioned umbilical venous and arterial catheters (UVC and UAC) are associated with increased rates of complications in newborns. Catheter insertion depth is often estimated using body surface measurement. We wished to determine whether estimating insertion depth of umbilical catheters using birth weight (BW), rather than surface measurements, results in more correctly positioned catheters. Interventions/outcome Newborns were randomised to have UVC and UAC insertion depth estimated using formulae based on BW or using graphs based on shoulder-umbilicus length. The primary outcome was correct catheter tip position on X-ray determined by one radiologist masked to group assignment. Results UVC insertion was successful in 97/101 (96%) infants but the catheter was not advanced to the estimated depth in 22. There was no difference in the proportion of correctly positioned UVCs between groups (weight 16/51 (31%) vs measurement 13/46 (28%), p=0.826). The tips of 52 (54%) UVCs were in the portal venous system or too low on X-ray. Attempted UAC insertion was successful in 62/87 (71%) infants. More infants in the weight group had a correctly positioned UAC tip (weight 29/32 (91%) vs measurement 15/30 (50%), p=0.001). Conclusions UVCs were often not inserted to the estimated depth, and their tips were in the portal venous system or too low on X-ray. Using BW to estimate insertion depth did not result in more correctly positioned UVCs. UAC insertion attempts were often unsuccessful, but when successful, using BW to estimate insertion depth resulted in more correctly positioned catheters. Trial registration number (ISRCTN17864069).

Accuracy of five formulae to determine the insertion length of umbilical venous catheters

“…More recently, Kieran et al reported no difference in the proportion of correctly placed UVC between the Dunn (28%) and Shukla (31%) methods 16. These proportions are lower than the predicted success rates that we calculated (44.9% with Dunn’s nomogram and 52.9% with Shukla’s formula; table 2).…”

“…These proportions are lower than the predicted success rates that we calculated (44.9% with Dunn’s nomogram and 52.9% with Shukla’s formula; table 2). Fifty-four per cent of infants in this study had their UVCs in a low position or the liver 16. We speculate that our predicted success rates were higher because 41% of infants were excluded from the analysis as their catheter tip was too low (>1 cm below the diaphragm) to allow for calculations of predicted success rates.…”

Accuracy of 11 formulae to guide umbilical arterial catheter tip placement in newborn infants

“…Verheij et al showed a significantly lower success rate with Dunn’s normogram than with Shukla’s formula (63% vs 87%, p<0.05) in infants with mean GA of 32 weeks 16. These findings were similar to those of Kieran et al (50% vs 91%, p=0.001) in a randomised trial, which included infants with median GA of 29 weeks 19. In contrast, we found that the mean difference to T8 using Dunn’s normogram was smaller, that is, more accurate than Shukla’s formula; however, this did not translate to an important difference in predicted success rates (60.8% vs 62.1%).…”

“…This may explain the difference between our predicted success rate (60.8%) and Kieran’s success rate (50%) when the Dunn’s normogram was used. The success rate using Shukla’s formula in Kieran’s study was much higher than our predicted success rate (91% vs 62.1%) 19. In both studies, misplaced UAC tips were ‘too high’.…”

Positioning newborns on their back or right side for umbilical venous catheter insertion

“…At the time of catheterisation, a proportion of UVCs do not pass through the DV into the inferior vena cava (IVC) but instead pass into the portal venous circulation (PVC) . In a randomised study where we compared two methods of estimating umbilical catheter insertion depth (ID) in newborns who had a UVC inserted while they were supine , we confirmed that UVCs were in the PVC 23% of the time. We believed, however, that UVCs entered the PVC more frequently, characterised by an inability to pass the catheter to the estimated ID and consequently being too low on X‐ray.…”