Transplant Flashcards
Absolute contraindications to liver transplantation:
Active sepsis Extrahepatic malignancy Severe cardiac disease Severe respiratory disease Ongoing alcohol or IV drug use Confirmed AIDS Poor compliance: "inability to co-operate with life long medical supervision" Severe neurological or developmental impairment
Relative contraindications to liver transplantation:
Renal failure
Extensive upper GI or biliary surgery
Confirmed HIV (it should be fully suppressed with HAART)
Social problems leading to poor compliance
Orthotopic liver transplantation:
you remove the whole recipient liver, and you put the whole donor liver into the normal anatomical position.
Sites of anastamosis in liver Tx
Hepatic artery to hepatic artery
Portal vein to portal vein, or to bypass graft (if there is portal vein thrombosis)
Vena cava may be preserved, or there may be a portal vein bypass
Phases of liver Tx
“preanhepatic”,
“anhepatic”
“neohepatic” or “reperfusion” - characterised by wild haemodynamic instability, as vasoactive products of anaerobic metabolism are flushed out of the donor liver by the first pulses of the recipient’s blood
Complications following liver transplant
Respiratory complications:
- Right hemidiaphragm paralysis
- Portopulmonary hypertension
- Pleural effusion
Circulatory complications:
- Profound hypotension
- Massive hypertension
Neurological complications:
- Hepatic encephalopathy
- Seizures
- Intracranial haemorrhage
- Central pontine myelinolysis
Metabolic complications
- Hypoglycaemia
- Lactic acidosis
Renal complications
- Acute renal failure (ATN)
- Hepatorenal syndrome
- Tacrolimus toxicity
- Intra-abdominal hypertension
Graft-related complications
- Primary graft non-function
- Acute and hyperacute rejection
- Graft infection and sepsis
- Hepatic artery thrombosis
- Portal vein thrombosis
- Biliary leak
- Perigraft haemorrhage
Idiosyncratic features of the transplanted heart
Autonomic disconnection:
No cardiovascular response to hypotension; thus, sepsis or spinal/epidural anaesthesia result in massive hypotension
Atropine has no effect on heart rate
Digoxin has no effect on heart rate
There is no bradycardia in response to cholinergic drugs, eg. neostigmine
There is no reflex tachycardia in response to GTN
Adenosine has an exaggerated effect, and one should use 1mg doses
Inotropes have an exaggerated effect, perhaps with the exception of isoprenaline (?)
Coronary artery disease is accelerated in these people
Rejection following heart transplant
Hyperacute rejection usually happens within the first few hours, and is antibody-mediated
Acute rejection usually happens after the first week, and is T-cell mediated
Surveillance biopsies are required; occasionally the graft continues to function in a manner which does not allow clinical features of failure to manifest
High dose methylprednisolone pulse therapy is the treatment of choice
Early problems following heart transplant
Bradycardia: The transplanted heart is usually bradycardic for the first 1-2 weeks; ultimately, the rate stabilises at 90-100 bpm, but early pacing is usually required.
Arrhythmias should not occur - they are uncommon; when arrhythmias are seen, it is usually a prelude to acute rejection.
Diastolic dysfunction due to reperfusion stunning is a feature of the first 24 hours
- Filling pressures of 10-15mmHg may be required
- If this diastolic dysfunction fails to resolve within a week, it is a sign that acute rejection may be taking place.
Hypertension occurs for two reasons:
You have just transplanted a heart into a patient who has adapted to chronic systemic hypotension; the new healthy heart will produce a vigorous increase in arterial blood pressure.
Cyclosporin drugs (especially tacrolimus) cause hypertension as one of their side effects
All of this is bad - hypertensive encephalopathy may result from systolic pressures in excess of 140mmHg. GTN or something similar should be used.
Idiosyncratic features of management following lung transplant:
Early bronchoscopy is performed to check the anastomosis
Chest drains are on continuous suction routinely
Antibiotic prophylaxis is guided by pre-op sputum cultures
Antifungal prophylaxis commonly consists of nebulised amphotericin
The patients end up extubated early - 24 hrs post-op
Specific issues of ventilation post-op lung Tx
The major goal is to protect the grafts from ventilator-induced injury
FiO2 should be weaned aggressively
Tidal volume should be under 6-8ml/kg
Peak inspiratory pressure should be under 30 cm H2O
Specific issues in the single-lung recipient:
PEEP should be limited to 10 cm H2O in single-lung transplant recipients, as the native lung will accept more of the pressure (it has better compliance)
The patient should be positioned native lung down for the first 6 hours, so as to decreased blood flow to the graft (decreases the risk of pulmonary oedema)
Idiosyncratic properties of the transplanted lung
The lung is denervated:
- Cough reflex is lost - voluntary cough and chest physio are required
- Mucociliary clearance is poor
- Pulmonary vascular resistance seems unaffected
The bronchial blood supply is sacrificed
- The donor bronchial vessels are not anastomosed, and the bronchi receive hypoxic pulmonary arterial blood, as well as diffused oxygen.
- Over the first month, collaterals form.
- The period of ischaemia can lead to a series of long term complications: Bronchial stenosis, Bronchiomalacia, Bronchial anastomotic dehiscence
The graft is highly susceptible to pulmonary oedema
- The lymphatic clearance of fluid is interrupted
- The capillary integrity is poor due to reperfusion injury
- The patient usually returns from theatre with 10-15% extra body mass, due to fluid
- Fluid management in ICU should therefore be intelligent and cautious - some centres aim to remove 1L/day as tolerated by kidneys
Complications of lung transplantation
Primary graft failure
Acute rejection
Early surgical complications
Late surgical complications
Chronic rejection
Complications of lung transplantation - Primary graft failure
“Acute non-immune-mediated injury”
Essentially, ALI/ARDS of the graft, due to reperfusion injury
Occurs within 72 hrs, in 25% of recipients
Mortality is around 50%
Treatment is supportive; there is nothing specific to offer. ECMO may be required.
Complications of lung transplantation - Acute rejection
When mild, the findings are subtle, resembling a LRTI
When severe, the clinical picture resembles ARDS
Requires a bronchoscopic histological diagnosis
Pulsed methylprednisolone is the treatment of choice
Antibody-mediated rejection can occur very early (donor-specific antbodies) - this may require plasmapheresis.
