TREATMENT FOR ACUTE KIDNEY FAILURE

• Life-threatening Complication

Hyperkalaemia

Hyperkalaemia is most commonly dangerous in the context of acute kidney failure, and is important because it can cause cardiac arrest. Patients may occasionally notice muscle weakness or paralysis, but the significance of these symptoms is rarely appreciated, and usually there are no symptoms whatsoever. All doctors who work with acutely ill patients should be able to recognize the characteristic electrocardiogram (ECG) appearances, which are a better indicator of cardiac toxicity than the serum potassium level.

Pulmonary oedema

The most serious complication of salt and water overload in acute kidney failure (usually iatrogenic) is the development of pulmonary oedema. Severe cases are dramatic. The patient is terrified, restless, and confused. Examination reveals cyanosis, tachypnoea, tachycardia, widespread wheeze or crepitations in the chest, and a gallop rhythm (if the heart can be heard). Investigation demonstrates arterial hypoxaemia and widespread interstitial shadowing on the chest radiograph.

The patient should be sat up and supported, and given oxygen by face-mask in as high a concentration as possible using a reservoir bag. Furosemide (frusemide) may work as a venodilator but is unlikely to provoke a substantial diuresis in a patient with kidney failure. Morphine can relieve symptoms rapidly and should be given in small (2.5 to 5 mg) doses, repeated if necessary and if tolerated, and with the opioid antagonist naloxone to hand in the event of deterioration due to toxicity. An intravenous infusion of a venodilator such as isosorbide dinitrate may be helpful.

The definitive treatment for pulmonary oedema caused by kidney failure is the removal of fluid by haemodialysis or haemofiltration. Acute peritoneal dialysis is much less effective in this capacity and should only be considered in circumstances where haemodialysis and haemofiltration are not available. The immediate beneficial effects of venesection of 200 to 400 ml of blood from the patient in extremis should not be forgotten.