Renal transplantation is the definitive treatment of choice for children with end-stage renal failure. Clinical outcome indices in paediatric renal transplantation remain inferior to those in adults due to the higher incidence of acute tubular necrosis and graft loss from vascular thrombosis and primary non-function [1-3]. After Institutional Research Ethics Board approval, the anaesthetic and perioperative management of 34 consecutive patients who received a renal transplant at the Hospital for Sick Children, Toronto, Canada between January 2001 and August 2003 were reviewed. Results are expressed as mean ± SD.
There were 20 male and 14 female patients, with a mean age at transplant of 11.2 ± 5.3 yr (range: 2–18 yr) and weight of 36.1 ± 15.2 kg (range: 13– 60 kg). There were five patients who weighed less than 15 kg. The aetiology of renal failure is listed in Table 1. Twenty-nine patients were receiving dialysis (17 haemodialysis, 12 peritoneal dialysis) at the time of transplantation. Five patients did not receive dialysis prior to renal transplantation as these patients were receiving donor organs from family members. Live-donor grafts were used in 56% of patients, 35% received a cadaveric adult kidney and 9% received a cadaveric paediatric kidney.
All patients were intubated and ventilated after induction of anaesthesia with intravenous agents: propofol (29 patients) or sodium thiopental (5 patients). Crystalloids, 5% albumin or red blood cell concentrate were given at 53 ± 24 mL kg−1 (range: 22–109 mL kg−1) to maintain intravascular volume and achieve a central venous pressure (CVP) of 14 ± 2 mmHg (range: 11–19 mmHg) prior to release of renal vessel cross clamps. Ten patients (29%) received packed cells perioperatively to achieve a haemoglobin of 8–10 g dL−1. Mannitol (0.5–1.0 gkg−1) and furosemide (1 mg kg−1) were administered intravenously prior to release of cross-clamps to ensure a brisk diuresis. Eleven patients (32%) required inotropic support with dopamine up to 10 μg kg−1 min−1 after release of cross clamps. Vascular anastomosis sites were the iliac vessels (32 patients) and inferior vena cava/aorta (2 patients).
Graft survival was 94% at 1 yr. Renal vein thrombosis occurred in two living-related recipients each weighing less than 20 kg resulting in early graft loss. Venous thrombosis also occurred in one cadaveric adult kidney recipient (recipient weight <20 kg), which was successfully treated with anticoagulation therapy and an inferior vena cava filter. High-resolution Doppler ultrasound of the renal allograft was performed in the operating room after incision closure to identify all three cases of vascular thrombosis.
All patients were cared for postoperatively in a paediatric intensive care unit (ICU). Postoperative complications included pneumothorax (1 patient) and acute tubular necrosis (3 patients). One patient developed pulmonary oedema requiring tracheal re-intubation and mechanical ventilation. Five patients remained intubated on admission to the paediatric ICU (three patients weighing <20 kg). One patient had Klippel–Feil syndrome, scoliosis and restrictive lung disease and required ventilation for 5 days. Three patients with focal segmental glomerulosclerosis required plasmapheresis postoperatively. Five patients required surgical exploration within 24h postoperatively for venous thrombosis (3 cases) and bleeding (2 cases).
The rate of paediatric renal transplantation has been increasing in North America over the last 10 yr. With a concomitant increase in the incidence of end-stage renal disease, this trend is expected to continue. The benefits of renal transplantation in children are now well established and survival figures for older children are comparable to the adult population. A decade ago the 1-yr graft survival figures from the North American Paediatric Renal Transplant Co-operative Study was 79% . More recent data demonstrates an improvement in graft survival to 92% . In our study, the 1-yr graft survival rate was 94%.
Infants and small children weighing less than 25 kg are at highest risk for graft loss and mortality of any group undergoing renal transplantation . Our experience was in keeping with this finding. All three episodes of renal vein thrombosis occurred in recipients less than 20 kg, two of which were organs from living-related donors and resulted in graft loss. The adult kidney can hold 300 mL of circulating blood volume and a significant portion of the infant’s cardiac output . Despite the assumption that early graft loss may be more likely in this situation some studies have demonstrated that the increased mass of the adult-sized donor kidney may be protective for the infant recipient, provided there is no evidence of acute tubular necrosis . Renal vein thrombosis was the single most important determining factor in graft failure in our study. High-resolution Doppler ultrasound of the renal allograft was used after incision closure in all cases to confirm forward diastolic flow and adequate perfusion, a technique that is well established in the literature .
Acute tubular necrosis is a major determinant of graft failure in infants and children. It renders the kidney more immunogenic and is associated with a higher chance of acute rejection. Reversal of acute rejection in the first year is crucial for long-term survival [4,5]. Episodes of hypoperfusion and ischaemia in the perioperative period likely contribute to delayed graft function and, therefore, immunogenic activation to a greater extent than previously realised. Immunogenic activation makes the donor graft susceptible to early and delayed graft loss secondary to an increase vulnerability to host immunogenic attack . It is for this reason that optimization of physiologic variables to ensure prompt graft perfusion at the time of unclamping and in the immediate reperfusion interval that follows is essential.
It is in this regard that the role of the anaesthesiologist is important in contributing to graft survival [7,9]. Crystalloids, 5% albumin or red cell concentrate were administered to maintain intravascular volume and achieve a normal to high CVP prior to release of renal vessel clamps. Infants receiving an adult kidney need adequate volume to avoid inadequate perfusion, acute tubular necrosis and renal artery thrombosis. Therefore aggressive volume loading prior to unclamping may be necessary bearing in mind the small but real risk of pulmonary oedema. In our study, one patient developed pulmonary oedema requiring tracheal re-intubation and mechanical ventilation for less than 24 h. The current study is consistent with others in that 1-yr graft survival in paediatric patients is now over 90%. Despite this significant morbidity may be associated with paediatric renal transplantation, as 13 patients in our series experienced complications within the first 24 h after transplantation.
Our data demonstrates 1-yr graft survival rates of over 90%, however infant recipients may be at higher risk for graft failure. The consequence of early renal graft loss is devastating for the patient and family, especially in living-related donor cases. Vigilance and attention to detail in the anaesthetic and perioperative management remains pivotal in the success of paediatric renal transplantation.
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