The curriculum asks for knowledge of 'the issues of anaesthesia for renal transplant surgery '.
An SAQ on renal transplant surgery from March 2017 had marks available for intra-operative organ optimisation & perioperative analgesia, as well as perioperative management of CKD.
In CRQ format, the March 2023 (68% pass rate) iteration of the question was 'reassuringly well answered '.
Renal transplant is the preferred therapeutic option for ESRD i.e. CKD Stage 5
It confers a long-term survival benefit over lifelong dialysis (either peritoneal or haemodialysis)
Pre-operative
One needs to know the underlying aetiology of their CKD/need for renal transplant
Elucidate the presence of coalescing diseases e.g. HTN, IHD, diabetes
Enquire about dialysis:
Method e.g. PD vs. HD
Lines/fistulae
Last dialysis date
Fluid status and dry weight
Drug history; often polypharmacy
FBC
Patients are frequently anaemic; iron replacement, erythropoietin or blood transfusion to [Hb] >70g/L if necessary
Platelet number may be normal although function may be compromised
A raised WCC should prompt investigation for infection ± consideration of cancelling surgery in view of mandatory post-operative immunosuppression
Clotting studies and group & cross-match
Post-dialysis U&E, including chloride, bicarbonate and acid-base status
K+ levels >6mmol/L require pre-operative dialysis
K+ levels 5 - 6mmol/L may be judged on an individual basis
Routine observations inc. NIBP
ECG; need one from booking and one more pre-operatively to ensure no changes following electrolyte imbalance
CXR
TTE ± further cardiovascular investigations if warranted
Some measure of functional capacity e.g. CPET
In short: prehabilitation
Slightly longer:
Patient education (see below)
Correct anaemia
Optimise cardiac comorbidities
Smoking and alcohol cessation
Nutritional assessment + optmisation + carbohydrate drinks pre-operatively
Avoid routine pre-operative placement of central lines
Avoid excessive fluid volume replacement
Management of medications
Continue aspirin, statins, β-blockers and diuretics
Patients are typically hypertensive
Beware the patient on zero anti-hypertensive agents; it implies their cardiovascular physiology is too frail to tolerate an anti-hypertensive agent!
Usual treatment is with ACE-I/ARA and, as HTN is often refractory, other drugs including CCB, ɑ-blockers and β-blockers
These drugs impair autoregulation and ability to respond to hypovolaemia under anaesthesia
Consider withholding ACE-I pre-operatively, unless there is LV dysfunction
Pre-operative dialysis will reduce plasma potassium concentration, correct acidosis and potentially avoid need for post-operative dialysis
Conversely, it will cause relative intravascular depletion and lead to transient anticoagulation
'If in doubt, dialyse'
Patient education and counselling
Introduction to principles of ERAS
Managing expectations for the peri-operative period
Identifying potential challenges and barriers to optimal recovery and discharge
Education around the importance of maintaining cardiovascular health and keeping well on the transplant waiting list
Intra-operative
AAGBI as standard inc. neuromuscular monitoring
Consider depth of anaesthesia monitoring in the elderly/frail patient
Arterial line only if concerns about cardiac status
Avoid forearm and antecubital veins for cannulae in case need future fistula
Use RIJ for CVC (avoid subclavian as may compromise future fistula formation)
± haemodialysis catheter
± Oesophageal Doppler
In general, consider the renal elimination of the drugs used
RSI should be considered, especially in patients with autonomic dysfunction ± delayed gastric emptying
Propofol and thiopentone are viable agents - reduce dose of thiopentone in uraemia to correct for changes in plasma protein binding
IV opioid options include fentanyl and remifentanil
mMrphine's active metabolites are renally excreted, so it should probably be avoided (although can be used in lower doses)
Rocuronium is the NMBA of choice for RSI
Use of atracurium for intra-operative paralysis may be preferential as rocuronium (30%) and the rocuronium-sugammadex complex are renally excreted
Suxamethonium and its potassium-boosting ways are not welcome here
Both sevoflurane and isoflurane are suitable maintenance agents, with neither associated with post-operative renal dysfunction
For cases >4 MAC-hours, desflurane is associated with less fluoride ion production although this is not demonstrably clinically significant
TIVA is a suitable alternative
Generally supine + lateral roll as necessary
Meticulous AVF care is required:
Avoid cannulating it
Wrap it with cotton wool (both literally and metaphorically)
Careful position to avoid traction/compression injuries
Paracetamol
Incremental doses of fentanyl (up to 1μg/kg) [or morphine (up to 0.1mg/kg)]
TAP blocks
Consider a neuraxial technique, which may reduce perioperative opioid requirements, although issues include:
Existing thrombocytopaenia/coagulopathy
Need for immediate post-operative haemodialysis (with anticoagulation)
Therefore higher risk of spinal/epidural haematoma
More pronounced hypotensive sequelae in patients with cardiac disease/on anti-hypertensives
Variable
Target
MAP
≥80 - 90mmHg
MAP at X-clamp removal
Normotensive
Fluid volume
≤2.5L (or to optimise CO)
CVP (at graft perfusion)
12 - 14cmH2 O
A higher MAP target preserves residual native renal function, reduces delayed graft function and reduces the need for post-operative dialysis
A CVP of 12 - 14cmH2 O at time of graft perfusion improves graft survival and function
Fluid management must strike a balance:
Adequate fluid therapy for optimised CO and renal perfusion, and reduced blood viscosity, may improved outcomes
Over-administration of fluid risks post-operative pulmonary oedema; outcomes may be better if total fluid administration is <2.5L
Balanced crystalloid or HAS are options; avoid 0.9% NaCl and HES
Other treatments aimed at improving renal outcomes:
Mannitol 20% 0.5g/kg at time of arterial clamp removal; no great evidence for improved graft survival
Dopamine use is ever-decreasing as no evidence it improves patient or graft outcomes
Blood transfusion; use allogenic CMV-negative blood judiciously as may cause hyperkalaemia or fluid overload
Perioperative care bundle
Standard measures apply:
Maintain normothermia
Maintain normoglycaemia
Appropriate VTE prophylaxis
Multi-modal anti-emesis
Intra-operative immunosuppression
High-dose methylprednisolone administered at the time of venous anastomosis
Administration of basiliximab 20mg slow IV (or rituximab)
Post-operative
Routine admission to L2/3 care is not absolutely necessary, but should be considered for usual indications
A dedicated post-transplant unit is essential as staff are trained in the care of these patients, and any complications
Standard ERAS targets including early mobilisation, early removal of drains and catheters
Paracetamol
TAP blocks ± wound infusion catheters
An opioid PCA
Fentanyl
Oxycodone
If a morphine PCA must be used, reduce the bolus dose to 1mg
Urine output and fluid management
Target appropriate MAP post-operatively; suboptimal MAP increases incidence of delayed graft failure
Transplant of live donor kidneys usually results in immediate return of urine output
Cadaveric transplants may not produce urine straight away
Titrate fluid therapy to match urine output in the post-operative period (or 30ml/hr + UO)
Encourage early return to oral intake to reduce risks associated with excessive IV fluid administration
Daily clinical assessment of volume status including weight, and input / output, providing the patient with a daily oral intake target
Immunosuppression
Modern regimens consist of two phases: induction (see above) and maintenance
Ciclosporin was historically used but is less fancied now owing to effects such as:
Neurological: post-transplant seizures, tremor, encephalopathy
Reduced GFR
Hepatic impairment
Hypertension
Biological agents are used instead to induce immunosuppression (e.g. basiliximab 20mg slow IV, alemtuzumab 30mg IV over 1hr)
These agents reduces the incidence of early cellular rejection, but carry risks such as:
Anaphylaxis or anaphylactoid reactions
Perioperative cardiac events
Infectious complications
Cutaneous events