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Anaesthesia for Renal Transplantation

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Anaesthesia for Renal Transplantation
Photo by Robina Weermeijer / Unsplash

Take home messages

  • Kidneys are the most commonly transplanted organ
  • Be very careful with their fluid balance
  • Be aware of the immunosuppressant agents you might need to use

Finders keepers

Surgeons first attempted to take the piss in 1933, in Soviet Russia.

It failed due to a lack of understanding of organ rejection, so it wasn't until 1954 that they actually succeeded, with surgeons Joseph. E. Murray and J. Hartwell Harrison transplanting a kidney from one identical twin to the other.

Deliberately removing an important bit from one human and plumbing it into another is a strange concept, be it blood, skin, organs or an entire face - but it's also rather splendid.

Renal transplantation is no different, and is one of the most widely recognised whole-organ transplant procedures that is responsible for many happy faces around the world each year.

And so you need to know how to anaesthetise them.

Dead or alive

Organs are rather important, and a few billion years of evolution have ensured we put them all to good use, so removing them to give to someone else generally requires one of the following conditions to be met:

  • The donor doesn't need it anymore
  • The donor has a spare

For kidneys, you can do either - with a living or cadaveric donor.

For this post, we're focusing on the recipient, so it doesn't matter an awful lot which of the two you're using, apart from the timing - with cadaveric donors having an understandably less flexible schedule than their living counterparts.

💡
Around 3000 kidney transplants are performed each year in the UK.

Perioperative considerations

Your patient is only having this procedure because their kidneys don't work, so clearly you're going to have some CKD puzzles to contemplate before you drift them off to sleep.

To make a list, we just need to ask 'what do the kidneys do?'

Oh wait - everything

  • Fluid balance
  • Electrolytes
  • Blood pressure
  • Acid-base balance
  • Haematopoesis
  • Drug clearance
  • Hormone synthesis

Now you zoom out, and look at all of their other comorbidities, as well as the causes of their renal dysfunction in the first place

  • Diabetes
  • Hypertension
  • Autoimmune disease
  • Infections
  • Infarctions (MI and stroke)

Then you also have to think about the treatments they've already had, their side effects and interactions:

  • Immunosuppressants
  • Biologics
  • Hormones

Add to that our population is living longer and developing increasingly complex comorbidities and chronic conditions, and you've got yourself quite a pharmacological conundrum on your hands.

Not easy stuff.

Preoperative investigations

For everyone:

  • Full blood count (anaemia and to rule out active infection*)
  • Electrolytes (potassium, chloride and bicarbonate)
  • Blood gas (acid-base balance)
  • Group and save (for transfusion)
  • ECG (electrolytes and IHD)
  • Chest xray (to assess fluid status and evidence of heart disease)

For those with significant heart disease:

  • Echocardiography (+/- stress echo)
  • Coronary angiography
  • Cardiopulmonary exercise testing

*They're going to need immunosuppression afterwards, so no bugs please.

What meds are they on?

Usually a fairly impressive cocktail, including but not limited to:

  • Antihypertensives (ACEi, ARB, B blocker, Ca antagonist, alpha blocker)
  • Aspirin and clopidogrel
  • Diuretics
  • Statins
  • EPO
  • Sodium bicarbonate
  • Antibiotics
💡
A uraemic patient on aspirin and clopi may have normal clotting tests and platelet count, but will bleed a lot.

How do I anaesthetise them?

First, you'll want to grab or be a consultant.

Then you want big IV access, on the opposite side to the AV fistula.

Then work through the following.

Induction

Consider RSI, even if fasted, as these patients often have gastric autonopathy (is that a word?)

  • Propofol or thiopental*
  • Strong opioid (fentanyl/remifentanil)

*Both are safe, but you have to be cautious as they have exaggerated hypotensive effects in renal failure patients.

If you are still using thiopental, remember to reduce the dose in a uraemic patient as they will have less plasma protein for it to bind to.

Or, you know, just use propofol like the rest of us.

Muscle relaxation

You need the patient to be intubated, to be very, very still indeed, and you also need to be able to take control of ventilation to manage acid-base balance if needed.

So muscle relaxation is a must.

  • Rocuronium (30% renally excreted so will last longer)
  • Suxamethonium (avoid if potassium >5.5)
  • Atracurium (old school and organ independent)

The rocuronium-sugammadex complex is also renally excreted, and it seems that they recover muscle function much slower than people with normal kidney function.

Monitoring and access

  • AAGBI monitoring
  • Arterial line (contentious - risk vs benefit of damaging sites for AVF - definitely avoid femoral arteries)
  • Central line*
  • Consider a vascath depending on what the post-op plan is
  • Consider oesophageal doppler if lots of fluid shifts expected
  • Warming as standard
  • Aim for a MAP of 90mmHg, especially when the graft clamp comes off
  • CVP 8-10mmHg

*Avoid going anywhere near an established arteriovenous fistulae, because of both steal phenomenon and vessel stenosis.

Maintenance

  • Inhalational or TIVA (as usual)
  • Entirely academically, inhalational agents may produce fluoride that may be of issue to an unhappy kidney, but this doesn't appear to be clinically significant
  • Remifentanil metabolism is kidney-independent, which is nice

Positioning

  • Wrap fistula limb in cotton wool and position carefully to avoid excess traction or compression
  • Supine
  • Arms out

Fluid management

Here goes.

  • Avoid normal saline, use balanced crystalloid instead
  • You have a dry patient to begin with, if they've just had dialysis
  • You need to maintain blood pressure to all kidneys involved, as well as all the other organs too
  • Avoid hyperkalaemia
  • Avoid fluid overload, especially in anuric patients
  • Avoid hyperviscosity
  • Maintain electrolyte balance

Not easy.

If someone mentions mannitol to you - it has been used for its colloidal and free radical scavenging properties, as a dose of 500mg/kg at the time of clamp removal, but doesn't seem to affect graft outcomes on a clinically significant level.

The worse a patient's oligo/anuria, the more fluid they will have removed at each dialysis session in the run up to their operation, making them much more vulnerable to big fluid shifts and cardiovascular instability once they're asleep.

Analgesia

OBVIOUSLY NOT NSAIDS

  • Regular paracetamol
  • Morphine*
  • Transversus abdominis plane block
  • Local infiltration to wound +\- catheters
  • Fentanyl PCA
  • Epidural is possible, however the risk of hypotension and graft hypoperfusion means they're not commonly used

*Metabolised in the liver, but active analgesic metabolites are renally excreted and will accumulate in renal failure. This means the initial loading dose is the same, but ongoing maintenance doses need reducing.

For the exam, generally avoid giving morphine because they're testing whether you realise it accumulates in renal failure.

Immunosuppression

Now as anaesthetists we often give post-op antibiotics - with varying degrees of willingness - in the hope of boosting the immune system's defences and avoiding infection.

But here, we're also then going to deliberately suppress their defence system in order to allow the foreign kidney to flourish.

Something along the lines of:

  • Some new swanky biological agent like rituximab
  • Maybe azathioprine
  • Usually high dose methylprednisolone at time of venous anastomosis

What about living donor nephrectomy?

In the exceedingly unlikely event that they ask you about anaesthetising the donor for a living donor transplant, here are the key points:

  • Consultant surgeon and anaesthetist
  • TED stockings and LMWH
  • No antibiotics (although evidence may be changing this)
  • GA plus regional (epidural is okay, because there isn't a donor kidney to worry about)
  • Lateral position with head down and pneumoperitoneum
  • Avoid NSAIDs because they're likely to have a slight AKI afterwards
  • Positive fluid balance
  • Avoid vasoconstrictors
  • Heparin 5000 units just before clamping
  • Protamine after kidney isolated
  • Normothermia

Useful Tweets and Resources

References and Further Reading

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