How to Use POCUS to Place Umbilical Lines

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Umbilical arterial catheters (UACs) and umbilical venous catheters (UVCs) are the most commonly used central lines in the NICU and serve as the primary vascular access in critically ill newborns for the first 1 to 2 weeks after birth. (1)(2) Confirmation that the catheter tip is appropriately positioned is crucial before starting intravenous or intra-arterial fluids and medications. Malposition of umbilical lines or migration after placement may lead to thrombosis, cardiac arrhythmia, pericardial or pleural effusion, cardiac tamponade, and hepatic or renal injury. (3)(4)The insertion depth of a UVC (Video) is most commonly calculated using either the Dunn or Shukla methods developed in 1966 and 1986, respectively. (5)(6) Currently, radiography remains the most common imaging modality for confirming UVC or UAC tip position. (7)(8) Migration after placement may be identified by means of serial radiography. More frequent or even daily radiography for monitoring the position of the catheter tip during the 7 to 14 line indwelling days results in increased radiation exposure. (9)Studies from 2010 and later comparing radiography and ultrasonography found that point-of-care ultrasonography (POCUS) is not inferior to radiography in confirming UAC and UVC positioning, effectively identifying malpositioned UVCs even after radiographic confirmation of appropriate placement, while also reducing the time required for line placement and minimizing the necessity for radiography (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) In 2016, Saul et al conducted a prospective blinded study on 25 neonates and were able to use POCUS to confirm that 100% of UVCs and UACs were in good position. (12) A randomized controlled trial demonstrated similar successful umbilical venous line placement rates with POCUS versus the control group. (24)POCUS is fast, effective, and often more readily available than radiography because the latter method requires a technician to travel to the NICU to obtain the image. The use of POCUS has been shown to decrease the total time needed for line placement. (11)(22)(23) Providers often experience a waiting period between the insertion of the catheters and the arrival of the radiography technician to obtain the confirmatory image. Access to POCUS allows for real-time position checks and aids in repositioning of the catheter, thus reducing the wait time for confirmation and reducing the number of radiographs needed before securing the catheter in its final position.Some studies have suggested that radiography may not be sufficient for confirming umbilical line position. Franta et al showed that only 38.4% of UVC tips were in optimal position despite the line having been confirmed to be “in good position” via radiography. (10) Additional observational studies demonstrated that POCUS was able to identify malpositioned umbilical venous lines despite radiographic confirmation of adequate position and thus, POCUS had greater sensitivity and specificity for identifying optimal line position. (13)(14)(15)(16)(17)(18)(21) In 2022, a randomized controlled trial including 53 neonates compared the use of POCUS during UVC placement to the standard of care (radiography only). (20) The rate of malpositioned catheters was lower in the POCUS group compared with the standard group (relative risk = 0.57, 95% confidence interval [CI] = 0.34 to 0.94, P =.019). POCUS-guided placement reduced the need for catheter repositioning at the time of the procedure, thus reducing total procedure time by a mean of 6.04 minutes (95% CI = 3.46 to 8.62, P =.005). Even after initial placement, the UVC tip may migrate in up to 50% of patients during the first week after birth, and this was noted on prospective monitoring of the line with ultrasonography. (10)Insertion of the UVC is often hindered by difficulty in passing the catheter through the ductus venosus (DV). Studies have described a failure rate of 25% to 50%, which is due in large part to the angle of the DV in relation to the umbilical vein, portal veins, and hepatic veins (26); the umbilical vein gives rise to the DV at an angle of 45 to 60 degrees. (27) Figure 1 demonstrates the vascular anatomy in the hepatic region. Dynamic POCUS can facilitate the passing of the UVC by:A prospective case series showed that the use of dynamic POCUS rescued 23 (72%) of 32 neonates who initially failed UVC placements. (26)Indications for UVC placement include the need for intravenous fluids, medications, transfusions, and any other uses for central venous access. A consensus guideline recommends the placement of UVC in preterm infants born before 28 weeks’ gestation, neonates who receive mechanical ventilation or oxygen supplementation greater than 40% with continuous positive airway pressure, and neonates who are hemodynamically unstable. (28) Indications for UAC placement include continuous arterial monitoring of blood pressure, frequent blood draws, and in some cases, administration of fluid and medications if central venous access is not available.POCUS can be used in the following scenarios: For real-time dynamic assessment and guidance of UVC placement as the catheter tip passes through the DV.Following catheter placement, POCUS can identify the UVC and UAC tip positions.After the catheters are placed and secured, POCUS can also be used for serial monitoring of the catheter position and assessment for line migration and malpositioning to ensure that the UVC and UAC tip positions remain in the appropriate positions.Contraindications to umbilical catheterization both with or without POCUS include untreated bacteremia, omphalitis, gastroschisis, omphalocele, peritonitis, and necrotizing enterocolitis. Contraindications to ultrasonography include skin breakdown or exposure of soft tissue at the site of interest. (1)(2)When possible, the clinician obtains written consent from legal guardians. Institutions may perform umbilical line cannulation without consent as this central line placement is a standard-of-care procedure in neonates in emergent settings. Use of POCUS guidance does not warrant additional consent. As with all procedures, the clinician needs to perform a time-out before the start of the procedure and should identify the landmark of interest (eg, the umbilical stump).Radiant warmerSterile field∘ Sterile gown, sterile gloves, cap, and mask∘ Sterile drapes∘ Bactericidal solutionInsertion tools∘ Umbilical tape∘ Scissors∘ Scalpel∘ Iris forceps∘ Nontoothed forceps∘ Needle driver∘ 3-0 silk suture∘ Sterile saline flush or heparinized flushIntravenous tubing and connectors∘ Three-way stopcock∘ Intravenous tubingCatheters∘ Umbilical vein catheter: Double-lumen 3.5 Fr for infants <3.5kg, 5F catheter for infants ≥ 3.5 kg∘ Umbilical artery catheter: Single-lumen 5 Fr for infants >1.2 kg, 3.5F catheter for infants >1.5 kgUltrasound machine∘ Linear probe 4 to 12 Hz acceptable for subcostal and abdominal views∘ Phased array probe 6 to 8 Hz allows flexibility to do short-axis and subcostal views∘ Sterile sleeve for ultrasongraphy∘ Sterile gelPerform sterile preparation using institutional procedure (eg, iodine, chlorhexidine gluconate). If the clinician intends to use POCUS within the sterile field, the clinician should dress a sterile sleeve over the ultrasound probe and use sterile ultrasound gel. Ensure that there is patient-image concordance. Apply neonatal cardiac or vascular settings on the ultrasound machine per manufacturer instructions.The Video depicts the insertion of umbilical catheters with ultrasound guidance.For dynamic POCUS during UVC placement, place the ultrasound probe on the abdomen at the level of the diaphragm in a sagittal orientation. (29) Identify the heart and right atrium above the diaphragm, and the liver below the diaphragm. Identify the umbilical vein, portal sinus, and ductus venosus (Fig 1). To test the patency of the DV, use the agitated saline approach. (30) Instill saline in small rapid inf

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