Intro to Pediatric IR

NPO 2-4-6-8 Rule for Sedation:

Maintenance Fluids:

Anesthetize Creatively:

Some practices use anesthesia for all pediatric cases and can sometimes give some sedation prior to IV access.
EMLA cream on site 30 or 60 min prior to IV or access.
Lidocaine dose limit 5 mg/kg (without epinephrine) and 7 mg/kg (with epinephrine).
Buffer 1 mL NaHCO2 to 9 mL lidocaine to decrease burning sensation.

Use Contrast Sparingly - risk of AKI rises significantly >5 mL/kg/SCr

Rough Estimate for Angiography Rates - take adult numbers, divide by percentage of kid weight, and add 1 to the rate

Often only hand runs
Need to heparinize (75-100 U/kg) for patients <15 kg due to risk of catheter associated thrombosis

Be Mindful of Fluid Shifts:

Children are more sensitive for fluid shifts in terms of blood loss, flushes, and paracentesis.
Blood volume is ~100 mL/kg preterm, 80 mL/kg term, 70 mL/kg infant, 65 mL/kg children.
Limited fluid to 10% blood volume.

Heparin Dosing:

Generally 50-100 U/kg bolus but many suggest staying closer to 100 U/kg as the majority of access complications involve thrombosis

tPA won’t work as well in neonates:

Biopsies

Err on getting more tissue for trials.
Wilms like HCC has classic imaging findings and often doesn’t need biopsy. Also any biopsy upstages it to stage 3.
Larger cores are needed for neuroblastoma and often need to sample multiple parts of the lesion for diagnosis.

Central venous access

Symmetric tip superior to split tip in terms of 120d patency (89 v 45%) and catheter failure rates (13x less) with equivalent blood flow rates
Tunneled right IJ superior to left with less infections and dysfunction

Absent/Diminutive Portal Vein:

Initial work up for consideration of surgical creation of a Rex shunt includes wedged portal venogram for presence of intrahepatic portal veins and communication between them (sometimes require transhepatic access), hepatic pressure, liver biopsy.
- Rex shunt = SMV/IMV/coronary vein to LPV using vein vs graft material
- Decompresses the portal system and increases hepatic flow
Post-Rex shunt imaging: US at 1d, 2wks, 1 mo, 3mo, 6mo, 1yr, annually -> MRV/CTV if concern for stenosis/recurrent symptoms (*Post-op there is usually mild focal narrowing at the anastomosis*)
Endovascular Management of Anastomotic Stenosis plasty/stenting:

Best to access right portal branch for better access/angle to shunt.
Angioplasty +/- stenting followed by 24 hr obs, baseline US next day, 3 mo ASA/clopidogrel.
Complications: rare, mainly bleeding related to transhepatic access, others include portal venous thrombosis, intrahepatic pseudoaneurysm.

Abernethy Malformation Closure

Type 1 = congenital absence of portal vein with complete diversion into systemic veins where the SMV and splenic vein drain separately into the IVC (1a) or form short extra-hepatic portal vein that drains into a systemic vein (1b)
Type 2 = hypoplastic portal vein with portal blood diversion into the IVC via extra-hepatic communication
Three key questions:
- Is there intact intrahepatic portal venous flow -> Type 2 shunts can be closed safely
- What are the portal pressures -> pressure gradient <10 mmHg and absolute occluded pressure <25-32 mmHg can be closed in one step. Higher pressures require two steps.
- What is the shunt morphology -> short/broad is good for surgical ligation while long/narrow is better endovascularly

Enteric Access

AMT GJet: 14, 16, and 18 Fr. Larger internal lumen at same Fr but stiffer though reports of perforation seem similar.
Halyard MIC-KEY: 14, 16, 18, 22 Fr. Smaller internal lumen, but softer.
Corpak G Tube: 14 or 16 Fr
*Use manufacturer specific stoma measuring device as they are unique to the tube*

Sizing: <5 kg case by case basis, 5-10 kg generally 14 Fr x 1.0 cm x 15 cm, >10 kg stomal length measurements
De novo low-profile GJ placement: 34 placements, median age 9.4 mo, one major complication of balloon inflated in SubQ tract, minor complications (11/32%) of dislodgement, skin irritation, leaking, tube migration into esophagus
Risk of bowel perforation with low-weight infants:

Study of 35 de-novo or conversion G to GJ in infant <10 kg: bowel perforation in 48-72 hrs in 3 (8.6%, 2 AMT 14F GJet, 1 G to GJ 16F Corpak), all with tube distal to ligament of Teitz
Ideally tip in distal duodenum rather than at ligament of Treitz

Drainages

Low threshold to drain non-simple parapneumonic effusions often with fibrinolytics