**3. Intra-operative and immediate post-operative considerations**

Although surgical and anaesthetic approaches and considerations are outside the scope of this chapter, intra-operative events have significant impacts on patient and graft outcomes. Review and documentation of intra-operative and immediate postoperative factors can help predict and guide subsequent clinical course (**Table 5**).

Any surgical complications or anatomical challenges (notably presence of multiple renal arteries, difficult bench surgery and renal capsule tear) should be communicated by the transplant surgeons as these can help predict perioperative complications. If available, intraoperative Doppler assessments should be documented to confirm adequate post-perfusion flow parameters in the transplanted kidney. Where there is perioperative concern regarding allograft perfusion, or early unexpected oligoanuria, an early duplex ultrasound may be requested to confirm flow in the transplant vessels.

Significant blood loss, requirement of inotropic support and intra-operative haemodynamic instability indicate suboptimal organ perfusion and are risk factors for delayed graft function (Section 5.4). Central venous line is placed at the time of surgery, and central venous pressure (CVP) is still used intra-operatively and in the immediate post-operative period. It is important to acknowledge controversies in absolute CVP targets, with studies advocating improved outcomes with high CVP (10–15 mmHg) targets at reperfusion [40, 41] and others observing increased kidney dysfunction with CVP >11 mmHg [42]. In general, intra-operative CVP trends can inform fluid management, but should not form the basis of a fluid management strategy due to inconsistent correlation with intravascular volumes [43].

Despite preoperative optimization, hyperkalaemia is common post-operatively due to tissue trauma and resorption of intra-abdominal blood. The presence of


#### **Table 5.** *Post-operative documentation.*

hyperkalaemia >6 mmol/L in the immediate post-operative period should prompt consideration of dialysis depending on the urine output. If graft urine output (with native residual renal function deducted) is >100 mL/h, it may be reasonable to manage the patient medically with insulin-dextrose infusion and loop diuretics. It should also be noted that intraoperative use of insulin-dextrose often results in rebound hyperkalaemia postoperatively.

#### **4. Perioperative fluid management**

Optimal fluid management strategy is contentious, although there is good evidence that fluid loading to maintain cardiac output and optimise renal perfusion, improves outcomes [44]. Intra-operative blood losses and fluid balance can be estimated through discussion with the transplant surgeon and anaesthetist and review of anaesthetic chart (Section 3). Currently, no studies on fluid management in the perioperative phase of renal transplantation exist to guide practice. A recent randomised trial demonstrated non-inferiority of a non-restrictive perioperative intravenous fluid strategy in high-risk abdominal surgery in terms of disability-free survival. Furthermore, the restrictive fluid strategy was associated with increased rates of acute kidney injury (8.6 vs. 5.0%. p < 0.001) [45]. Although generalizability to renal transplantation is uncertain, a restrictive fluid strategy should be avoided.

A common strategy for managing post-operative fluid replacement in the hours after kidney transplantation is to replace the urine output from the previous hour plus 30 mL to account for insensible losses. A loop diuretic and/or mannitol is sometimes administered during the transplant surgery to precipitate a diuresis, decreasing requirement for dialysis, but has not been shown to improve graft outcomes [46].

Frequent clinical assessment of the recipient's fluid status, including the jugular venous pressure, heart rate, blood pressure and urine output, is important to ensure adequate fluid replacement and to avoid volume overload. Traditional parameters and clinical assessment of fluid status, however, may be unreliable due to compromised homeostatic mechanisms in ESKD and the post-ischaemic transplanted kidney [47]. As soon as it is feasible post-transplant, recipients should be weighed with comparison to their preoperative weight as an objective guide to fluid status.

There is currently no evidence supporting one type of intravenous fluid therapy over another, although a pragmatic, registry-based, multi-centre, doubleblind, randomised controlled trial comparing balanced crystalloid solution (PlasmaLyte) with 0.9% saline on the incidence of delayed graft function in 800 adults and children with end-stage kidney disease (ESKD) receiving a deceased donor kidney transplant in Australia and New Zealand is currently underway (ACTRN12617000358347).

A good urine output in the early post-transplant period is a helpful indicator of early graft function, although it may not be possible to differentiate allograft urine output from native urine output in recipients who have significant residual renal function. Oligoanuria may be an indicator of delayed graft function or a harbinger of an early complication, especially if the urine output was good initially (Section 5.4). An urgent ultrasound is a useful investigation to assess perfusion of the allograft at the bedside and to check for evidence of ureteric or vascular complications. The presence of hypoechoic fluid collections may indicate haemorrhage or urinary anastomotic leak (Section 5).

Blood tests to monitor serum creatinine and electrolytes are collected immediately post-transplant and then 6–12 h to monitor renal function and exclude

**19**

**Table 6.**

Blood tests:

Alternate day CNI levels

Post-operative chest radiograph

*Common post-operative surveillance investigations.*

*Perioperative Care for Kidney Transplant Recipients DOI: http://dx.doi.org/10.5772/intechopen.84388*

**5. Early complications**

tions (**Table 6**).

hyperkalaemia. Some recipients may develop a significant diuresis, passing over a litre of urine per hour, and in this situation, frequent monitoring of blood tests 4–6

Complications in the perioperative phase are diverse, reflecting pre-existing transplant recipient comorbidities as well as individual surgical challenges. With the potential for there to be few symptoms from the denervated graft, most centres follow a protocol of investigations for early identification of post-transplant complica-

Generally, an early renal transplant duplex ultrasound can identify vascular or anastomotic complications including renal vessel thrombosis or compression. The resistive index (RI) (measured peak systolic velocity—end diastolic velocity/ peak systolic velocity), normally, between 0.60 and 0.80, with levels >0.8 suggesting abnormal perfusion of the allograft, is a widely reported measure of allograft perfusion for duplex scans but does not seem to correlate well with renal histology [48]. A positive correlation has been reported between RI and recipient mortality, and the strongest predictor of an elevated RI was recipient age, suggesting that RI may be an indicator of recipient vascular disease [48]. Consequently, although the

Similarly, nuclear medicine imaging, such as a mercaptoacetyltriglycine (MAG3) or diethylenetriamine pentaacetic acid (DTPA) renogram, can assist in the assessment of allograft perfusion and early graft function as well as identify a ureteric anastomotic leak. Radionucleotide scanning may give an indication of the likely

Electrolyte abnormalities are a frequent occurrence in the early post-transplant

period. Perioperative hyperkalaemia is often followed by hypokalaemia due to diuretics and polyuria combined with large volume IV fluid replacement. Hypomagnesaemia is exacerbated by the tubular effects of CNI therapy and is associated with an increased risk of post-transplant diabetes [51, 52]. Hypophosphatemia is almost universal as a consequence of elevated FGF23 and PTH levels [53, 54]. To reduce the chance of arrhythmias, intravenous electrolyte replacement should target potassium levels in the normal range (3.5–5 mmol/L) and a serum magnesium >0.4 mmol/L. Hypophosphatemia is not usually associated with adverse clinical sequelae, but if severe (<0.4 mmol/L) can also be managed with intravenous replacement. Many transplant recipients require ongoing oral replacement of potassium, magnesium and occasionally phosphate in the first few weeks post-transplant,

RI is commonly reported, clinicians need to be aware of its limitations.

**5.1 Haematological, biochemical and metabolic derangement**

although this may be limited by gastrointestinal adverse effects.

Daily capillary glucose levels—if abnormal, manage as diabetes mellitus

Twice daily full blood count and serum biochemistry

Duplex ultrasound imaging, usually at days 2–4 post-transplant MAG3/DTPA renogram as indicated by clinical progress

duration of delayed graft function [49, 50].

h is recommended to avoid over or under replacement of electrolytes.

hyperkalaemia. Some recipients may develop a significant diuresis, passing over a litre of urine per hour, and in this situation, frequent monitoring of blood tests 4–6 h is recommended to avoid over or under replacement of electrolytes.
