Kidney replacement therapy and dialysis in children: Case

This girl has severe acute kidney injury complicating the low cardiac output state that follows cardiopulmonary bypass and cardiac surgery, and she meets several of the AEIOU indications for urgent kidney replacement therapy. She has refractory hyperkalaemia with electrocardiogram changes, severe metabolic acidosis, and fluid overload with pulmonary oedema, and she is haemodynamically unstable on noradrenaline, which together dictate the modality of choice. ^[1]

Clinical findings

The picture is that of post-cardiac surgery acute kidney injury, a classic trigger in paediatric intensive care because cardiopulmonary bypass, the inflammatory response, and perioperative low cardiac output injure the renal tubules. Her oliguria of under 0.5 mL per kg per hour for 8 hours, her doubling creatinine, and her metabolic and electrolyte derangement place her in the failure stage of the modified RIFLE criteria. The hyperkalaemia to 7.0 mmol per litre with QRS widening is immediately life-threatening and reflects failure of renal potassium excretion. Her fluid overload of 11 percent with crackles and rising ventilator pressures signals that the excess fluid is now compromising her lungs, and her ongoing need for noradrenaline marks her as haemodynamically unstable. ^[1]

The three clinical questions at the bedside are whether she needs dialysis now, which modality is feasible, and what access is available. The answer to the first is clearly yes, because her disturbances are refractory and progressive with end-organ effects. The answer to the second follows her haemodynamic state, and the answer to the third is a central line, favouring the right internal jugular vein and avoiding the subclavian to preserve the veins she may one day need for a fistula. ^[1]