Hepatic Flashcards
End Stage Liver Disease
Considerations
Goals
Conflicts
Massive Variceal Bleed
End Stage Liver Disease
Considerations
Airway:
Aspiration risk due to ↑ gastric volume
Friable/edematous tissues
Multiorgan dysfunction:
CNS: encephalopathy
Cardiovascular: hyperdynamic circulation (↑ cardiac output, ↓ SVR), cardiomyopathy, portopulmonary HTN
Pulmonary: hypoxemia (intrapulmonary AV shunting, V/Q mismatch); restrictive lung physiology (ascites & pleural effusions)
GU: hepatorenal syndrome/renal failure
GI: U/LGIB from varices & AVM’s
Hematology: coagulopathy (↓ platelets, ↓ clotting factors, ↑ fibrinolysis) & immunodeficiency
Endocrine: hypoglycemia, hyponatremia, lactic acidosis
Etiology/associated conditions:
Viral (e.g. hepatitis)
Drugs (e.g. alcohol, acetaminophen)
Autoimmune (α-1-antitrypsin deficiency)
Hemochromatosis
Altered drug pharmacology (↑ volume of distribution, ↓ hepatic clearance, ↓ protein binding)
Altered fluid physiology:
Total body water excess (ascites) with intravascular volume depletion
Low albumin state
Reconsider elective surgery in very high risk patients (child-pugh class C or MELD > 20)
Goals
Identify & optimize multisystem complications
Avoid elective or non-emergent surgery in acute liver dysfunction
Pre-operative correction of coagulopathy & hypovolemia
Consider draining ascites to optimize respiratory mechanics
Anticipate fluid shifts & major blood loss
Appropriate use of hepatically-metabolized drugs
Universal precautions to prevent viral transmission
Conflicts
Need for regional vs. coagulopathy
High risk patients vs. elective surgery
Pulmonary hypertension vs. laparoscopy
Massive Variceal Bleed
Emergency situation
Needs emergent airway management with RSI, 2 suctions
Massive hemorrhage: give blood products as indicated, reverse coagulopathy, call massive tranfusion protocol
Pharmacologic:
Vasopressin 0.4 unit bolus followed by an infusion of 0.4 to 1 units/min
Ocreotide: 50 mcg bolus, then 50 mcg/hr infusion
Balloon tamponade: blakemore (minnesota) tube
Endoscopic management of varices
TIPS if endoscopic management fails
Liver Resection
Background
Considerations
Goals & Conflicts (Preoperative, intraoperative, postoperative)
Liver Resection
Background
Lobectomy, segmentectomy, or wedge resection
Indications for hepatic resection: hepatic metastases, benign & malignant primary hepato-biliary tumours, donation for transplantation, trauma
Liver = highly vascular; receives 25% of cardiac output; 80% supplies by portal vein, 20% by hepatic artery
↑ risk of multi-organ dysfxn if underlying hepatic dz
Considerations
Potential for massive blood loss
Need for invasive monitors & access
Risk of postop liver dysfxn & coagulopathy
Risk of hypoglycemia during vascular occlusion & after resection
Altered drug metabolism in setting of liver dysfxn
Temporary occlusion of blood supply during liver resection (surgical technique to minimize bleeding) –> ↓ CO up to 10%, ↑ LV afterload by 20-30%
Surgical manipulation may cause transient IVC compression & ↓↓ venous return
Potential co-morbidities: cancer 4M’s (mass effects, medications, metastases, metabolic abnormalities), liver disease, EtOH, hepatitis C, carcinoid
Goals & Conflicts
Overall goals are to avoid & manage postop liver dysfxn, & minimize blood loss
Avoid hepatotoxins
Preoperative:
Assess adequacy of preop cardiopulmn fxn to tolerate surgery
Determine risk of postop liver failure
Depends on extent of resection & underlying liver dz
likely safe to remove 50-80% of liver in young pts w/ nl liver parenchyma
↑ risk if sig EtOH consumption
Assessment of extent of liver dz
Child-Pugh B & C –> liver resection likely contraindicated
Pts may have portal vein embolization to induce liver hypertrophy preop
Intraoperative:
Arterial & central venous access, large bore IV access, rapid infusion system immediately available +/- minimally invasive CO monitoring
consider cell salvage esp if non-malignant lesion
Thoracic epidural must be carefully considered w/ risk of postop coagulopathy
Single-shot neuraxial opioids, IV opioid PCA, continuous wound infusion catheters are alternatives
Minimize CVP to ↓ blood loss
Minimize pre-resection IV fluids (max 1 ml/kg/hr)
titrate vasopressors to maintain optimal perfusion pressure
Reverse Trendelenburg positioning
Diuretics (Mannitol, furosemide)
NTG infusion
Minimize PEEP
Consider TXA
Maintain normothermia, nl pH, nl Ca2+ & normoglycemia
Monitor for & correct coagulopathy
Consider N-acetylcysteine to limit ischemia-reperfusion injury (mixed evidence)
Atracurium/cisatracurium preferred (unaffected by liver dysfxn)
Postoperative:
Monitor for postop liver dysfxn, coagulopathy
Glucose infusion, correction of coagulation & electrolyte abnormalities prn
Common to develop sig ascites (self-limiting) during 1st 48 hrs –> monitor for hypovolemia
Avoid acetaminophen until liver fxn returns to nl
