Anaesthesia for paediatric renal transplant

Pre transplant assessment

An anaesthetic assessment should have been completed pre-operatively. This will appear as a multi departmental anaesthesia assessment in concerto.

Know the recipient’s usual range of blood pressures, ‘native’ urine output, time of last dialysis and recent electrolyte profile. Chronic anaemia is usually well tolerated in chronic renal failure patients.

The renal team will complete the update sheet for anaesthesia prior to surgery, including specific medications pertaining to the operation, daily fluid intake and urine output, target blood pressure for kidney perfusion. This will be found in the patient notes.

Children who have been on dialysis will have had an ECHO within the past year, although if not yet on dialysis this may not have been done routinely. A neck vessel ultrasound would have been done if previous lines or <5yr old.

Logistics

Patients will be admitted to 26b and return to PICU HDU post-operatively from level 8 PACU .

A scope booking will be completed by the renal team for deceased donor transplants .

1st call is the general on-call anaesthetist with the on-call liver transplant anaesthetist as backup.

Preparation and equipment

• Operating theatre temperature should be kept at >23ºC.

• Forced underbody air-warming blanket available.

• Fluid warmer should be primed (in line burette without flow restrictor added to standard giving set for < 20kg).

• Plasmalyte is the preferred fluid.

• Paediatric equipment trolley should include various sizes of central venous catheters and epidural needles (including 18G 5cm Touhy needle).

Intraoperative management

Central access is mandatory.

Invasive arterial pressure monitoring is mandatory.

Urine catheter to be inserted.

Note: The immunosuppressive regimen will be determined by the transplant nephrologist based on the donor/recipient risk profile. The transplant team will prescribe the immunosuppressive medication. The immunosuppressive regimen may involve a combination of steroids, tacrolimus, mycophenolate mofetil and/or basiliximab).

Communication with surgical team is vital at this stage and for clamp removal/reperfusion.

Please record time the kidney is taken off ice and when the cross clamp is removed for documentation of cold and warm ischemic times.

Haemodynamic management post reperfusion

Most donor kidneys are adult sized. An adult kidney sequesters a large proportion of the circulating volume of a child recipient and requires significantly increased cardiac output to maintain renal perfusion. Maintaining adequate renal perfusion is important to avoid acute tubular necrosis and renal artery thrombosis.

Clamp removal - treat rebound hypotension

There may be hypotension secondary to reperfusion of relatively ischemic tissues distal to the clamp and the adult kidney sequesters circulatory volume. There is also potential for blood loss from an anastomotic leak. Target CVP around 15mmHg.

Target Systolic BP approaching donor systolic BP (likely MAP>75, SBP>120). Specific targets will be advised on the transplant update sheet by the on call renal physician and can be discussed during the procedure. Transplant surgeons can also guide on real time perfusion of the kidney.

Consider:

• Appropriate volume loading - maintain Hb > 75 g/L (lower transfusion trigger usually well-tolerated d/t chronic anaemia)

• low dose noradrenaline (to 0.1mcg/kg/min) especially if using epidural

• low dose adrenaline (0.03-0.05mcg/kg/min)

Post-operative pain management

• Refer to Pain team.

• NSAIDS are NOT to be given.

• Oxycodone PCA/NCA +/- background infusion.

• Epidural is not routine but can be considered if specifically indicated. If epidural is inserted, careful thought should be given to the ease of BP maintenance post-transplant.

Transfer and handover to PICU

The recording of urine output should begin at time of completion of ureteroneocystomy (ureteric re-implant) and continued through the time the patient is in Level 8 PACU.

Unless there is a strong clinical indication the patient should be extubated and taken to L8 PACU. Once stable they can be taken to PICU/HDU:

• This is an expedited PACU stay to ensure safe extubation and adequate analgesia prior to transfer to PICU/HDU.

• The anaesthetist should accompany the patient for transfer and provide PICU handover.

At completion of the transplant the on call renal physician should be called as they will want to be present in PICU on arrival.

‘Supranormal’ circulation and volume are required for early post-operative period, including transfer to PICU.

Recipients < 15kg

These are a high risk group with increased rate of vascular complications .

In smaller children vascular anastomosis are usually performed to the inferior vena cava and aorta or common iliac artery. Vascular thrombosis is a common cause of graft failure (2-12 %) and requires meticulous surgical technique and tissue perfusion.

The large adult kidney introduces an increase in the volume of the vascular circuit and may act as a shunt .

Sufficient cardiac output and volume load is required to maintain perfusion of the transplanted kidney . Cardiac output may need to be supernormal to maintain early perfusion without vascular compromise.

Aim to maintain:

• Blood pressures within the parameters determined pre operatively by the renal team, likely to be:

  • Systolic BP > 100-110mmHg

  • an absolute minimum of MAP > 75mmHg (50th centile for > 1 year old)

  • CVP > 12mmHg

• Target may be determined by donor kidney *be guided by renal physician recommendation.

• Low dose adrenaline should be considered in addition to noradrenaline .

Smaller children are more likely to require post operative ventilation due to the aggressive fluid regimen intra-operatively and possible respiratory embarrassment due to the large adult kidney compromising diaphragmatic function.