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
17
Q
Lung transplant:
How is the surgery usually done?
Where is it anastomosed?
A
- Lateral thoracotomy
- usually lung with poorer function is replaced
- Bronchial anastomosis more common that tracheal anastamosis
18
Q
Lung transplant:
Issue with induction?
maintenance technique?
A
- Prone to hypotension with induction d/t intravascular volume depletion
- give reduced doses
- Maintenance
- balanced anesthetic- VA + narcotic w/NMB
- avoid N2O- may exacerbate bullous emphysematous disease, PHTN, or intra-op hypoxemia
- Fluid restriction is optimal- use small volumes of colloids and pressors (CVP <7)
19
Q
Lung transplant:
ventilation
When is CPB indicated?
A
- Use lung protective ventilation
- TV 6 ml/kg
- PEEP
- lowest FiO2 settings
- PCV
-
Hypoxemia during single lung ventilation
- PEEP to the dependent lung
- CPAP to the nondependnet lung
- PA clamping of the non-ventilated lung by surgeon
- CPB indications
- inability to oxygenate despite above efforts
- inability to provide adequate ventilation
- RV failure: TEE is very helpful to evaluate RV and need for CPB
20
Q
Lung transplant:
What happens after re-anastomosis?
A
- following re-anastomosis of atrial/pulmonary vein patch, bronchus, and PA, the lung is unclamped and perfused
- hypotension can be seen, but not usually as severe as w/liver
- Hemostasis is checked
- may use FOB to remove secretions and blood from freshly anastmosed lung
- Ventilation is attempted with new lung
- After closing, attempt to exchange DLT for single lumen ETT
- indication to wait for exchange: significan oropharyngeal edema, high PEEP, or need for differential lung ventilation
21
Q
Lung transplant:
How are double lung transplants done?
A
- Supine position, clamshell incision vs midline sternotomy
- deflate lungs before sternotomy
- En bloc double lung tx requires CPB, can use standard ETT
- Bilateral sequential tx requires lung isolation (DLT)
- expect severe post-op pain, thoracic epidural advisable
22
Q
Lung transplant:
complications?
A
- Acute transplanted lung failure
- acute graft rejection
- inadequate pulmonary venous drainage
- primary graft dysfunction
- allograft dysfunction w/in 72 hours of ransplant
- factors:
- prolonged ischemic time w/ reperfusion injury
- advanced donor age
- recipient PHTN
- use of CPB or ECMO
- iNO therapy may be used to decrease PVR and improve oxygenation
- methemoglobinemia risk
23
Q
Heart Transplan:
Plan
A
- Cold ischemia is ~6 hours or less
- Ischemic time starts with aortic cross clamping during the harvest and ends with removal of cross-clamp from recipient aorta
- Emergent case with fast, efficient evaluation
- review recent CXR and labs
- evaluate pulm, hepatic, and renal compromise associated with CHF
- get blood products ready (FFP, cryo, plt, PRBCs)
- determine if previously exposed to aprotinin–can have anaphylaxis with re-exposure
- Aprotinin- bovine trypsin inhibitor used to reduce bleeding during surgery
24
Q
Heart transplant:
Access
pressors
A
- Evaluate:
- current inotropic infusions
- chronic meds for heart failure
- if on ACEI, may want to start vasopressin
- presence of LVAD, pacemaker or defibrillator
- antiarrhythmic devices need to be interrogated and reprogrammed
- Access
- A-line pre-induction
- large bore IV for resuscitation prior to induction
- Inotropes and pressors on hand
- dobutamine or milrinone
- epi, NE, dopamine
- vasopressine
- phenylephrine
- Hve ultrasound ready for CVL and PAC placement
25
Q
Heart transplant:
anesthetic technique
A
- Surgery is done by median sternotomy with CPB
- many different techniques, may leave behind SA node causing extra P-wave
- High dose narcotic for induction and maintenance
- alternative is balanced technique with lower narcs and IA
- NMB
- Hypotension may not be responsive to ephedrine or phenylephrine
- TEE should be done after induction and after weaning from CPB
- risk of intracardiac thrombus is increased in the recipient heart
26
Q
Heart transplant:
Heparin dosing
cannulation
PAC
CPB
A
- Heparin dosing is similar as for other CPB procedures
- Cannulation is done so that the surgical field is bloodless
- PAC should be withdrawn from the surgical field prior to resection of the native heart
- can be readvanced after removal of the superior cava cannula
- Maintenance of CPB and weaning from CPB are associated with the same issues as for other cardiac surgical procedures ???
27
Q
Heart transplant:
What should be done prior to weaning from CPB?
What is the significance of deneravation?
Why is acute R heart failure a complication?
A
- Prior to CPB:
- air should be evacuated
- heart is reevaluated with TEE
- Donor heart is denervaed so feedback for inotropy and chronotropy are lost
- isoproterenol is used for its direct effects on cardiac B receptors to increase graft heart rate
- temporary pacing may be needed
- Acute right heart failure is a complication b/c donor heart is not used to high PVR
28
Q
Heart transplant:
What is resting HR for transplanted heart? Why?
How does this affect CO?
Which drugs can be used to increase HR?
A
- Transplanted heart has no autonomic influence so HR is determined by SA node. HR 100-120
- CO is HR x stroke volume; if HR is fixed, SV becomes dependent on preload–these pts are sensitive to hypovolemia
- Drugs to stimulate HR:
- those that directly stimulate SA node:
- epi
- isoproterenol
- glucagon
- those that directly stimulate SA node:
- Drugs that DONT stimulate HR in a transplanted pt:
- Those that indirectly stimulate SA node
- atropine
- glyco
- ephedrine
- Those that indirectly stimulate SA node
29
Q
Heart transplant:
How does a pt with a heart transplant respond differently to cholinesterase inhibitors?
A
- They will not cause decrease in HR, but will cause all other sypmtoms of PNS stimulation
- must still treat with glyco
30
Q
Denervation effects on pharmacology
(table)
A
31
Q
Pearls of transplant anesthesia
A
- Pre-op: focus on determining the degree of immunosuppression and transplanted organ function, evaluating for any co-existing infection and review co-morbidities
- Minimum labs:
- CBC
- CMP
- LFTs
- viral panels/viral loads
- CXR
- EKG
- strict aseptic technique for all invasive procedurese
- elective and non emergent cases should be postponed if pt is in active rejection or has an infection
- Regional anesthesia is controversial post-transplant
- avoid nasal intubation d/t immunocompromise
32
Q
Post-transplant anesthesia:
A
- Signs of infection are masked in post-tx pts
- evaluate fxn of grafted organ
- evaluate liver/kidney function
- immunosuppression can significantly effect renal elimination
- Post-renal tx: give adequate fluid for renal perfustion
- Maintain administration schedule of: abx, antiviral, antifungal, and immune suppression drugs
- Avoid NSAIDS in general
33
Q
Post-tx anesthesia:
What is unique about pt with tracheal anastomosis lung tx?
General guidelines for lung tx?
A
- Lung tx with tracheal anastomosis have no cough reflex below suture line d/t denervation
- increased risk of retained secretions and PNA and have increased airway hyperreactivity and bronchospasm
- General guidelines post lung tx
- evaluate:
- PFT
- ABG
- CXR
- prefer regional when feasible
- evaluate:
34
Q
Post heart transplant:
How does rejection present?
What will the heart respond to?
What wont it respond to?
A
- Rejection presents like CHF
- ECG and TEE before surgery
- cannot respond to:
- indirect agents (ephedrine, dopamine)
- peripheral attempts to induce hemodynamic changes
- carotid massage
- valsalva
- laryngoscopy
- B-receptor effects of epi and NE are exaggerated over alpha effects
- Isoproterenol is the mainstay of chronotropic terapy and should be in OR
35
Q
Infection risk after transplant timeline of causes
A
- within 1 month: likely caused by allograft
- 2-6 months: opportunistic infections or reactivation of disease syndromes (TB)
- Trimethoprim-sulfamethoxazole prophylaxis for pneumocystis pneumonia for at least 6 months
- inflammatory response blunted; sometimes diff to identify source of infection
- >6 months: many do well and infection risk decreases
- some have chronic progressive viral infections
- hep B, C
- CMB
- EBV
- herpes zoster
- some have chronic progressive viral infections
36
Q
Chronic immunosuppression:
side effects
overimmunosuppression
A
- General side effects:
- lower sz threshold
- diabetes
- CV disease
- increased infection risk
- increased malignancy risk
- pancytopenia
- decreased GFR
- hyperkalemia
- hypomagnesemia
- Overimmunosuppression leads to renal toxicity
- Protocols vary with transplant team
- be sterile!
- maintain abx, antifungal, and antiviral regimens
37
Q
What are the different anti-rejection regimens?
A
- Calcinereurin inhibitors (cyclosporin)
- Purine antagonists: Mycophenolic acids, azathioprine
- corticosteroids
- monoclonals (ATG, OKT3, IL-2 receptor antagonists)
38
Q
Calcineurin inhibitor:
name
MOA
SE
A
- Cyclosporin and tacrolimus
- MOA
- inhibits T-lymphocyte activation, differentiation, and cytokine production
- SE
- HTN
- hyperlipidemia
- ischemic vascular disease
- DM
- nephrotoxicity
- Tacrolimus metabolized by CYP450 3A4 and causes upregulation
39
Q
Purine antagonists:
names
MOA
SE
A
- Mycophenolic Acids, Azathioprine
- MOA- antiproliferative drugs
- SE-
- bone marrow suppression can cause pancytopenia
- Cardiac arrest and severe upper airway edema
40
Q
Corticosteroids
MOA
SE
A
- MOA- disrupt expression of many cytokines in T cells, antigen-presenting cells, and macrophages
- SE
- HTN
- DM
- hyperlipidemia
- weight gain
- GI ulceration
41
Q
Monoclonals:
name
MOA
SE
What is ATG?
A
- ATG, OKT3, IL-2 receptor antagonists
- MOA- depletion of T cells
- SE (rare)
- acute serum sickness (sx: jaw pain)
- stop the drug, plasmapheresis, corticosteroids
- acute serum sickness (sx: jaw pain)
- Antithymoglobulin (ATG)- purified rabbit immunoglobulin G taken from animals immunized with human thymocytes
