1% of pediatric malignancies are in liver, third most common intrabdominal following adrenal neuroblastoma and wilms. Hepatoblastoma nad hepatocellular carcinoma most common.
Significant periop m&m, up to 19%, perhaps less now.
Surgical resection is aimed at cure, and preop workup should identify structures adjacent to/encased by tumor including portal vein (2/3 of blood supply), hepatic vein and hepatic artery(1/3 of blood supply).
Two phases: pre and post-resection
Transverse abdominal incision, rarely thoracic cavity. First liver is mobilized and displaced to access retrohepatic vena cava –> can cause fall in CO and CVP. Ask surgeon to reposition liver for that to improve 🙂
Next step is isolation of portal vein, bile duct and hepatic artery. Ligation of hepatic veins is most difficult and hazardous –> think massive hemorrhage potential!
Pringle maneuver controls both common hepatic artery and portal vein (via hepatoduodenal ligament) – liver can tolerate 60 mins of occlusion, or 120mins of intermittent occlusion.
-inflow occlusion –> increased SVR up to 40%, decreased CO 10%, decreased MAP 15% in adults. Once unclamped, tend to go to baseline.
Total vascular occlusion: combined portal vessl with supra and infrahepatic IVC clamping. –> 40-60% decrease in Venous return and CO, and up to 80% increase in SVR and 50% HR increase. Unclamping increases CI and reduces SVR.
-hepatic impairment –> higher blood transfusion reqs, longer stay and increased mortality
-neoadjuvant chemo has systemic effects (cisplatin, doxorubicin, vincristine 5FU), in these cases a thorough cardioresp assessment is necessary
Anesthesia Planning I/O
-GETA, RSI for patients with ascites
-Nimbex used as it is metabolized by hoffman degradation
-Iso maintains hepatic oxygen supply via vasodilation of hepatic artery and portal vein, though some studies suggest ischemic preconditioning with Sevo limits p/o liver injury
– A line, large bore IVs
– Central line with CVP monitoring, though diaphragm pressure from retraction, clamping of liver vessels decreases venous return and CVP, and PEEP also impact usefulness of CVP
– monitor for hypoglycemia, especially during occlusion, monitor coags
-Minimize bleeding with low CVP (2-5), aim for euvolemia
-during total hepatic vascular exclusion, aim for higher CVP of 14, concern for reduced renal blood flow, so use of mannitol, lasix and low-dose dopamine have been used to prevent renal injury… ?benefit
-manual test clamp should be done as up to 15% of patients get extremely unstable after clamping, could require venovenous bypass
-Selective hepatic vascular occlusion preferred, but different implications: better for when you cannot lower CVP, such as right heart failure with high CVP, or when tumor encrouches on IVC
Blood: think of using TXA, cell saver, prepare to give PRBCs and products
-regional reduces post op pain, caudal or epidural
-caution of NSAIDs 2/2 renal damage from surgery, Tylenol is good in all but most extensive resection
Vascular Air Embolism
-right lobe large resections, close to IVC, or cavohepatic junction risks of air embolism
-remember TEE detects as little as 0.02ml/kg and doppler detects 0.05ml/kg
-trendelenberg, fluid resuc and vasopressors
PO to ICU, for management of hypoglycemia, respiratory insufficiency, pain, ascites, infection, bleeding, coagulopathy, portal/hepatic thrombosis, renal dx and liver dx