Transplants II Flashcards
1
Q
What variables are used to calculate the MELD score?
What is it used for?
What else is used for transplant selection?
A
- MELD variables:
- creatinine
- bilirubin
- INR
- sodium
- MELD score determines where pt is on “the list”
- Acute liver failure pts given priority, next is the highest MELD score, then compatible blood group
- Pts are screened for infectious diseases
- HIM
- CMV
- epstein-Barr
- malignancy
2
Q
ESLD pre-op:
Renal function
CV
A
- Renal dysfunction very common with ESLD
- creatinine not reflective of severity (slight increase will mean serious dysfunction d/t lack of muscle mass)
- Hepatorenal syndrome
- increased renal vasocontriction
- reduced GFR
- subsequent increase in creatinine
- impaired Na and H2O excretion
- CV- 30 day mortality often associated with CV causes
- CAD common- need extensive work-up
- Stress test
- cardiac cath- might need angioplasty pre-op
- ECHO
- Low SVR, high Cardiac index, and increased mixed venous sat
- Cirrhotic cardiomyopathy- will have blunted response to beta agonists
- CAD common- need extensive work-up
3
Q
ESLD pre-op:
pulmonary
labs
A
- Pulmonary:
- evaluate presence of portopulmonary hypertension
- PA pressure > 25 mmHg (>50 is absolute contraindication)
- PVR >240 Dyne
- PAOP 12 mmHg or lower
- Evaluate PFTs and presence of hepatopulmonary syndrome
- marked A-a gradient
- intrapulmonary shunting
- pleural effusions
- evaluate presence of portopulmonary hypertension
- Labs
- coags do not accurately predict bleeding in this population
4
Q
ESLD pre-op:
meds
A
- Recent treatment for Hep C with Telaprevir inhibits CYP3A, prolonging effects of versed
- usually avoid versed in general
5
Q
What are the changes that impair homeostasis and promote homeostasis in the ESLD pt?
(table)
A
6
Q
Liver transplant anesthesia “set-up”
Anesthetic technique?
A
- RSI- d/t gastroparesis and ascites and often these cases are emergencies
- Art line (maybe 2)- radial and fem
- central pressure is higher because vasodilation causes lower read in periphery
- PA catheters to follow PVR +/-
- TEE- caution with varices
- TEG- evaluate coagulation
- ability to monitor labs frequently (I-STAT)
- Rapid infustion catheters (14 g) and CVL
- Rapid infusion system primed and ready
- Colloids in the room
- active warming mechanisms
- Foley/NGT
- Use balanced technique: narcotic, inh agent, NMB
7
Q
Phases of liver transplant:
Pre-anhepatic
A
- Native liver is dissected and removed
- major vessels are compressed or occluded
- If there is a large drainage of ascites (>5L) at incision, replace with albumin to prevent renal decompensation
- give 6-8 g/L of ascites drained
- Phase ends with clamping of inferior vena cava, portal vein and hepatic artery and removal of liver
- major anesthetic goals:
- correct coagulopathies
- maintain IV volume for renal protection
8
Q
How should you handle the significant blood loss during the Pre-anhepatic phase?
A
- Follow TEG
- FFP used to maintain an INR of 1.5 or less
- may need Ca++ d/t inability to metabolize citrate
- Keep fibrinogen above 150 mg/dL with cryoprecipitate
- plt > 50K, but plt transfustions lead to poorer outcomes (may not need them with cryo/ffp)
- Call-save if not a transplant b/c of cancer
- activated factor VII: rescue for refractory critical bleeding unresponsive to more standard management
- TXA or aminocaproic acid
- EACA 5 g load and 1 g/hr infusion
- ensure adequate volume replacement- colloids preferred
9
Q
What happens during the anhepatic phase?
A
- Portal vein and IVC are crossclamped- may decrease CO up to 50%
- fluid volume load prior to clamping
- Some surgeons use a “piggyback” technique where the inferior vena cava is only patially occluded
- less derangement
- Alternative option is to use a temporary portocaval shunt or venovenous bypass
- V-V bypass has fallen out of favor
10
Q
What happens during the transition from anhepatic phase to neohepatic phase?
A
- New liver is anastomosed into place and re-perfused
- vena cava unclamped–adequate venous return to the heart restored
- BP and CO improve transiently
- Portal vein is then opened–cold, acidotic, hyperkalemic blood from below clamp goes directly into right heart
- significant drop in BP, bradycardia, other arrhythmiac, occasionally cardiac arrest: reperfusion syndrome
- Surgeon must communicate they will unclamp
- vena cava unclamped–adequate venous return to the heart restored
11
Q
What can be done to reduce the effects of the reperfusion syndrome?
A
- Perfect timing of calcium chloride and bicarbonate
- Have available for immediate use:
- epi
- vasopressin
- lidocaine
- atropine
- methylene blue (vasoplegia of reperfusion- not responding to pressors)
12
Q
What is the warm ischemia time?
A
- the time taken to sew the new graft in place
- can be very damaging to the graft, limiting warm ischemia time is critical to graft success
13
Q
What is the neohepatic phase?
A
- Hepatic artery and bile duct anastomoses- usually with a cholecystectomy
- looking for signs that the new liver is starting to function
- improvement in acidosis
- clearing of lactic acid
- improved homeostasis
- production of bile
- Renal function hopefully improves after reperfusion
- Assess bleeding on field and need for antifibrinolytics
- sources of bleeding are corrected
- drains placed and abdomen is closed
- Consider extubation based on surgical course and fluid status
14
Q
Lung transplant:
options
What has better survival?
A
- Single lung trasplant
- en bloc double (both at same time)
- sequential double (put one side in first then the other)
- heart-lung transplant
- Long term survival better for bilateral than single lung
- **double lung required for pathological process if remaining lung would jeopardize new lung
- CF
- severe emphysema
- PHTN
15
Q
What are the indications for lung transplants?
A
- Poor pulmonary function despite maximal medical therapy
- COPD
- O2 requirement
- FEV1 <25% of predicted value after bronchodilators and/or PaCO2 =55 mmHg and/or PHTN (esp with cor pulmonale)
- Idiopathic pulmonary fibrosis
- vital capacity <60-65% of predicted
- resting hypoxemia
- progression of disease despite therapy
16
Q
Lung transplant:
plan
access
post-op pain control
A
- Often emergency cases, may have full stomach. RSI
- Pre-op sedation: use caution, have minimal reserve
- GETA +/- thoracic epidural
- Access:
- CVL, PAC, A-line
- Fiberoptic bronch
- DL ETT
- Post op pain control
- thoracic epidural
- paravertebral blocks
- intercostal nerve blocks
- multi-modal analgesia
- ** chronically intravascularly volume depleted
- **pulmonary HTN common
30
Q
Denervation effects on pharmacology
(table)
A
