Transplant Anesthesia Flashcards
List the Canadian criteria for the neurological determination of death
- Established etiology capable of causing neurological death in the absence of reversible conditions capable of mimicking neurological death 2. Deep unresponsive coma 3. Absent brainstem reflexes as defined by absent gag and cough reflexes and bilateral absence of: a) motor responses excluding spinal reflexes b) corneal response c) pupillary response to light with pupils at mid size or greater d) vestibular-ocular responses 4. Absent respiratory effort based on apnea test. 5. Absent confounding factors a) umresuscitated shock b) hypothermia (<34) c) severe metabolic disorder capable of causing a potentially reversible come: glucose, electrolytes, inborn errors of metabolism, liver or renal dysfunction d) peripheral nerve or muscle dysfunction or neuromuscular blockade potentially accounting for unresponsiveness e) clinically significant drug intoxications (alcohol, barbiturates, sedatives, hypnotics)
Describe an apnea test and thresholds. What is the ancillary test (ie. in case of COPD and attenuated resp drive)
Period of pre-oxygenation followed by 100% oxygen delivered via the trachea upon discontinuation from mechanical ventilation. Thresholds upon completion of the apnea test (all of): a) PaCO2 >= 60mmHg b) PaCO2 >=20mmHg rise above the pre-apnea test level c) pH <= 7.28 d) no respiratory effort throughout test Ancillary test: global absence of intracranial blood flow
What are the systemic sequelae seen after brain death
1) hemodynamic instability (onset of brain death is associated with a transient period of hypotension with increased cardiac index and tissue perfusion. During this period, vasoactive drugs administered to increase blood pressure can cause rapid circulatory deterioration) 2) autonomic/catecholamine storm accompanies brain herniation 3) wide swings in hormone levels (adrenergic surges causing ischemia and repercussion injuries, followed by pituitary failure) 4) systemic inflammation 5) oxidant stress
Describe a routine donor hormone replacement regimen
1) triiodothyronine (4-µg intravenous [IV] bolus, then 3 µg/hr); 2) methylprednisolone, 15 mg/kg intravenously every 24 hours; 3) desmopressin, 1 U then 0.5 to 4 U/hr to maintain systemic vascular resistance (SVR) at 800 to 1,200 dyne/s/cm 5 (and reduce the polyuria of diabetes insipidus). 4) Insulin infusion to maintain blood glucose 120 to 180 mg/dL
Cardiac cath is requested for which heart donors
male donors >45 years old females >50 years old young donors with significant personal or family history of coronary artery disease.
What additional donor criteria are requested for pHTN recipients
younger donors short ischemic time low donor inotrope requirement oversized organs are preferred.
What criteria must all donor hearts meet
Human leukocyte antigen (HLA) typing ABO blood group compatibility The donor heart size should be within 20% to 30% of the recipient’s heart size.
What are the targets to maintain euvolemia during procurement. Goals of fluid therapy?
1) CVP 6-12mmHg 2) Pulmonary capillary wedge pressure <12mmHg 3) Avoid HES 4) Minimize the use of pressers
What are the blood and electrolyte targets during procurement?
1) Serum sodium levels <155mmol/L 2) Hct > 30% with pRBCs 3) FFP to maintain INR <1.5
What are strategies to maximize donor lung function?
1) bronchoscopy to rule out major pathology 2) Low CVP 3) diuresis prior to procurement 4) glucocorticoids 5) prostaglandin E1 to improve circulation of preservation solution
What are the ideal lung donor characteristics?
Age <55 years ABO compatibility Clear chest radiograph PaO >300 on FiO2 1, PEEP 5 cm H 2 O Tobacco history <20 pack-years Absence of chest trauma No evidence of aspiration or sepsis Negative sputum Gram stain Absence of purulent secretions at bronchoscopy
What donor characteristics are associated with poor outcome?
1) Advanced donor age (>55 years) together with 2) long ischemic time (>6 hours) are associated with poor transplant outcomes 3) poor concordance of height, lung capacity
DCD (deceased after cardiac death) account for what percentage of organ transplants?
10.6%
What are the DCD criteria?
1) unresponsiveness - often have severe whole-brain dysfunction but have electrical activity in the brain 2) apnea 3) permanent cessation of circulation and respiration (arterial monitoring showing pulse pressure of zero, or Doppler showing no flow) (The ACCCM argues that no less than 2 minutes is acceptable and no more than 5 minutes is necessary when determining death for potential DCD. )
What is a routine fluid load for living kidney donors?
A reasonable fluid protocol is to administer crystalloid at 10 mL/kg/ hr above calculated losses and to maintain urine output at about 100 mL/hr. Fluid loading overnight before surgery (vs. fluid administration starting with surgery) is associated with better creatinine clearance during the procedure, but this advantage is lost by postoperative day 2.
What is concerning regarding post-op pain management in living kidney donors?
1/3 have chronic pain
Regarding living liver donors, which procedure is most complex?
Left lateral segmentectomy (II and III) is used when adults are donating to children and are usually well tolerated. Right hepatectomy is required for adult-to-adult liver transplantation and is a major operation with significant risk. Complication rate 30%, morality of 0.2-0.5%.
The residual liver volume of the donor must be ____ of original volume to prevent “small for size” syndrome in the donor.
>35%
What are the complications of right hepatectomy donation?
air embolism, atelectasis, pneumonia, and biliary tract damage
What is the main intraoperative challenge for living liver donors?
Large liver resections may require virtually complete hepatic venous exclusion (cross-clamping of the hepatic pedicle usually without cava clamping). Not unexpectedly, venous return falls significantly because patients are healthy and without collaterals. But fluid boluses increase CVP which can increase bleeding. If vasopressors are needed, use vasopressin or levo.
What are the postoperative challenges after living liver donation?
- Pain control: INR peaks on POD1-3 when catheter would be removed. 2. Hypophosphatemia: Due to excessive loss in urine. Treat with sodium phosphate infusions to maintain phosphate levels 3.5-5.4mg/dL. 3. Elevated liver enzymes: typically return to normal in 3 months
What are the criteria for living lung donation?
Member of recipient’s extended family Age 18–55 years No prior thoracic surgery on donor side Good general health Taller than recipient preferred ABO compatible FVC and FEV 1 >85% predicted PO >80 mm Hg on room air No chronic viral diseases Normal electrocardiogram and echocardiogram Normal stress test in donors older than 40 years old
Why is immunosuppression a delicate balance?
Immunosuppressed patients who are undertreated risk rejection; overimmunosuppression can be toxic, especially to the kidneys.
What are the major risks of immunosuppression?
CNS: lower seizure threshold CV: DM, HTN, hyperlipidemia, atherosclerosis Renal: decreased eGFR, hyperkalemia, hypomagnesemia Heamtological: increased risk of infection and malignancy, pancytopenia Endocrine: Osteoperosis, poor wound healing
What are the common calcineurin inhibitors?
cyclosporine, tacrolimus
How do CIs work?
Inhibition of calcineurin, among other effects, modifies NFAT (nuclear factor of activated T cells) and frees nuclear factor-κB to translocate to the nucleus, where it enhances transcription of T-cell interleukin-2 (IL-2). Via these signal transduction pathways, CNI inhibits T-lymphocyte activation, differentiation, and cytokine production.
What are the common side effects of CIs?
hypertension (often requiring therapy), hyperlipidemia, ischemic vascular disease, diabetes, nephrotoxicity. Drug specific: Cyclosporine - acute nephropathy, prolongs pancuronium Tacrolimus - Polyneuropathy and encephalopathy, induces P4503A4
What is the leading cause of death in kidney transplant recipients?
Ischemic heart disease
Does ESLD confer protection against CAD?
No
What are the common CI doses?
tacrolimus are 0.15 to 0.3 mg/kg/day given in two doses. To switch from oral to intravenous tacrolimus, a starting dose of about one-tenth the oral dose can be used. To switch from oral to intravenous dosing of cyclosporine, usually about one-third the oral dose is used.
What is the immunosuppressive mode of action of corticosteroids?
Corticosteroids disrupt expression of many cytokines in T cells, antigen-presenting cells, and macrophages.
Side effects of corticosteroids?
hypertension, diabetes, hyperlipidemia, weight gain (including Cushingoid features), and gastrointestinal ulceration
In what specific situation are corticosteroids typically withheld?
during liver transplantation in recipients with hepatitis C because of concern that they contribute to hepatitis C recurrence (little advantage).
What are the polyclonal and monoclonal antibodies used for immunosupression?
- Antithymocyte globulin (ATG) - depletes T cells 2. OKT3 - blocking T cell function 3. Muromonab-CD3 (humanized-CD3) 4. IL-2 CD25 antagonists: basaliximab, daclizumab 5. CD80/CD86 antagonists: belatacept - block activation of T cells though the CD28 costimulatory pathway
What are the main classes of immunosuppressive drugs?
- Calcineurin inhibitors 2. Corticosteroids 3. Polyclonal and monoclonal antibodies 4. Mammalain target of rapamycin inhibitors (mTOR) - sirolimus (diltiazem raises plasma levels) 5. Azathioprine - metabolized to 6-mercaptopurine, purine analog that incorporates into DNA during S phase of cell cycle. Therefore, antiproliferative. 6. Mycophenolate - inhibits purine synthesis 7. Mesenchymal stem cells - MSCs have pleiotropic effects on the immune response, including antiproliferative T-cell function. No adverse reactions. W
What should anesthesiologists know when administering ATG?
Acute and severe serum sickness is a rare side effect of ATG administration in patients with previous exposure to rabbits. Presents as jaw pain, and is treated by stopping the drug, plasmapheresis, and corticosteroids.
What should anesthesiologists know when administering OKT3?
Acute administration of OKT3 in awake patients (especially first administration) may result in generalized weakness, fever, chills, and some hypotension. More severe hypotension, bronchospasm, and pulmonary edema have been reported. Formulations of OKT3 may require syringe filtering before administration.
What should anesthesiologists know when administering IL-2 receptor antagonists?
GI side effects, pulmonary edema
What should anesthesiologists know when administering CD80/CD86 antagonists
Infusion reactions can include hypotension, but acute reactions are usually mild.
What should anesthesiologists know when administering mycophenolate?
Leukopenia, thrombocytopenia, red cell aplasia, teratogenic
What is the most common cause of graft loss after corneal transplant?
rejection of corneal allografts
What are the most common diagnoses of patients on the renal transplant waiting list?
Type 2 diabetes 30% Hypertensive nephrosclerosis 21.5% Glomerular disease 19.7% Polycystic kidney disease 6.6% Tubular/interstitial disease 5.0% Renovascular/other vascular 3.6% Congenital or metabolic disease 3.1% Neoplasm 0.3% Other
What are the considerations for renal transplant recipients?
- high risk of CVS disease (stress test over 50) 2. anemia 3. hyperdynamic cardiac indices - higher PPF requirement 4. lung function - type I DM often present with reduced lung volumes and diffusing capacity 5. hypercoagulable states 6. cancer screen (mammography, pap smear, colonoscopy, PSA) 7. infection screen (dental evaluation and viral serology) 8. DM control 9. Dialysis before surgery 10. Complex serology typing 11. Uremic platelet dysfunction 12. Residual heparin from dialysis 13. All DM concerns 14. Altered drug metabolism - prolonged NMB - use cisatracurium,
What is the cold ischemia time for kidneys?
24-36hrs
What are the factors used in ECD kidney donors?
age, creatinine, stroke as cause of death, and hypertension
What are the serology matching specifics for kidney transplantation?
Blood type O kidneys are allocated to type O recipients, and blood type B kidneys are transplanted only in B recipients, except in the case of zero antigen mismatched candidates. Zero mis- matched kidneys have the same HLA A, B, and DR antigens.
Where are donated kidneys placed in the recipient?
Right iliac fossa or retroperitoneal space
What is the main operative consideration in renal transplant surgery?
Maintenance of renal blood flow, accumulation of drug metabolites (morphine, meperidine, remifentanil), electrolyte balance (as grafted kidneys are defective in concentrating urine and reabsorbing sodium)
What is the typical hemodynamic goals in renal transplant surgery?
systolic pressure >90 mm Hg, mean systemic pressure >60 mm Hg, and CVP >10 mm Hg. Usually attainable without pressers.
________ is the crystalloid of choice for kidney transplantation, and it preserves acid–base balance and electrolytes when compared with Ringer’s lactate or normal saline.
Plasma-Lyte
In renal transplant, what is started with the first anastomosis?
Diuresis with mannitol and furosemide
How is blood sugar important in renal transplant?
glucose >160 mg/dL (8.9) as a risk factor for acute perioperative renal dysfunction, likely associated with more ischemia-reperfusion injury. Target is 80-110 (4.4 - 6.1)
The selec- tive DA1 agonist _________ is used to preserve renal function during kidney transplantation in some centers and is a superior renal protectant, although not extensively studied.
fenoldopam
How long does renal transplant usually take?
3hrs
What are the common postoperative complications after renal transplantation?
ureteral obstruction and fistulae, vascular thromboses, lym- phoceles, wound complications, and bleeding.
How are liver recipients prioritized for transplantation?
Patients with acute liver failure are given priority for donor livers, then the patients with the highest MELD score and compatible blood group are next. MELD Score = 0.957 × Log e (creatinine in mg/dL) + 0.378 × Log e (total bilirubin in mg/dL) + 1.12 × Log e (INR) + 0.643
How important is creatinine in liver disease?
Serum creatinine levels are not extremely useful in capturing renal function in patients with liver disease. Even a small increase in serum creatinine in these patients suggests significant renal dysfunction.
List the complications of end stage liver disease
Central Nervous System Encephalopathy (confusion to coma) Pulmonary Respiratory alkalosis Pulmonary hypertension Cardiovascular : Hyperdynamic circulation Reduced systemic vascular resistance High cardiac index Increased mixed venous O2 sat Diastolic dysfunction Prolonged QT interval Blunted responses to inotropes Blunted responses to vasopressors Diabetes Gastrointestinal Gastrointestinal bleeding from varices Ascites Delayed gastric emptying Hematologic Decreased synthesis of clotting factors Hypersplenism (pancytopenia) Impaired fibrinolytic mechanisms Renal Hepatorenal syndrome Hyponatremia Endocrine Glucose intolerance Osteoporosis Nutritional/metabolic Other Poor skin integrity; pruritus Increased volume of distribution for drugs Decreased citrate metabolism
Why is TEE particularly good for HOCM?
PA capillary wedge pressure does not accurately reflect left ventricular (LV) volume in this population.
What are the criteria for diagnosing porto-pulmonary hypertension?
(a) setting of liver disease (b) mean positive airway pressure ≥25 mm Hg, pulmonary vascular resistance (PVR) >240 dyne/s/cm 5 , and PA occlusion pressure ≤12 mm Hg.
How is porto-pulmonary hypertension managed?
- Echo - Systolic PA pressure estimates are made by capturing the maximum velocity of regurgitant flow across the tricuspid valve, and this velocity is used in the Bernoulli equation for the pressure gradient between the right ventricle and the right atrium (∆P = 4V x 10^4 ). If moderate to severe pulmonary hyper- tension (estimated systolic PA pressure >50 mm Hg) is suggested, right heart catheterization is needed for direct pressure mea- surements. 2. Epoprostenol, Inhaled iloprost, Sildenafil, inhaled NO
PA pressure ____ mm Hg is an absolute contraindication to liver transplantation.
over 50
What spirometry pattern is seen in ESLD?
Reduced DLCO
What is the definition of hepatopulmonary syndrome?
HPS, a widened alveolar–arterial gradient in room air due to liver disease
How can a bubble study identify the location of shunts?
The microbubbles act as a contrast, and if intracardiac shunts are present, they appear within three heart beats after injection in the left ventricle. The later appearance of bubbles suggests intrapulmonary shunting.
List the intraoperative considerations for liver transplantation
- RSI as gastroparesis is common, + abdominal pressure from ascites 2. Lines: 2 arterial catheters (left radial and right femoral), PA catheter, continuous TEE, 2 large bore catheters, VVB bypass lines at select centres 3. Rapid infuser with ability to deliver 500ml/min 4. Cross match 10U RBC, 10 units FFP 5. Dissection: correction of coagulopathies and maintenance of intravascular volume for renal protection.
What are the 3 phases of liver transplantation?
- Dissection - blood loss may be high 2. Anhepatic - liver is functionally excluded from circulation, Involves clamping of IVC above and below, as well as portal vein and hepatic artery. Venous return falls 50-60%, causing hypotension. VVB can be used to increase venous return. 3. Neohepatic - marked by reperfusion of the graft, and represents the most treacherous time.
Is INR reliable predictor of bleeding in liver transplant? What is the INR target?
Although standard laboratory coagulation studies do not predict bleeding well, they are still the best tests available in real time in the OR. For this reason, FFP is used to maintain INR ≤1.5.