Acute Kidney Injury

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CLINICAL DESCRIPTION

Acute Kidney Injury (AKI) is a term that has now replaced the term Acute Renal Failure (ARF). It describes a sudden decrease in renal function occurring over a period of hours to days resulting in accumulation of nitrogenous waste products and disruption of blood volume, electrolyte and acid-base balance. Patients with acute kidney injury should be referred to a hospital. Carefully check the use of any drug in renal failure and reduce drug doses where required, see below;

Diagnosis in children

  • Anuria (urine output <0.2 ml/kg/hr) or Oliguria (<0.5ml/kg/hr for 6 hours)

OR 

  • Increasing creatinine (>0.3mg/dL above baseline)

 

CAUSES OF AKI

Prerenal AKI

  • Dehydration, bleeding, burns, nephrotic syndrome, septic shock, anaphylaxis, Heart failure,

Intrinsic AKI,

  • Tubular injury (often acute tubular necrosis (ATN)), Nephrotoxins, Infections (Malaria), Rhabdomyolysis, severe hemolysis, Vascular, Hemolytic uremic syndrome (recent bloody diarrhea), Vasculitidies (symptoms from other systems - lungs, brain, joints, skin), Congenitalanomalies of kidneys, Glomerulonephritis

Postrenal AKI

  • Bilateral urinary tract obstruction
  • Renal calculi
  • Neurogenic bladder
  • Posterior urethral valves
  • Spinal trauma/ tumours

CLINICAL FEATURES

SIGNS AND SYMPTOMS

  • Oliguria/anuria
  • Nausea, vomiting
  • Altered level of consciousness
  • Tachypnoea
  • Hypertension
  • Oedema
  • Pulmonary oedema
  • Look for clues for the cause of renal failure, which include:
    • Shock
    • Acute glomerulonephritis
    • Use of herbal remedies containing nephrotoxins

INVESTIGATIONS

  • Urine dipstick,microscopy and culture
  • FBC
  • urea, electrolyes and Creatinine
  • blood gases
  • malaria test
  • HIV
  • Hepatitis B and C
  • Renal ultrasound
  • Investigate underlying cause

TREATMENT IN CHILDREN

  • Monitoring of blood pressure, urine output, fluid balance (input and output), daily weight
  • Avoid nephrotoxins (NSAIDs, gentamycin, tenofovir)
  • Treat the underlying cause
Pre-renal AKI
  • If the child is in hypovolaemic shock and /or severely dehydrated, treat according to protocol

Refer

Renal AKI
  • Treat hypertension with Calcium channel blockers: Nifedipine initial dose 0.25 - 0.5mg/kg/day divided in 2 to 4 doses/day, titrate upwards up to 1mg/kg and if needed with Betablockers: Atenolol initial dose 0.5-1mg/kg 12 to 24 hourly
  • Treat fluid overload:
    • salt restriction
    • Frusemide 1-2 mg/kg IV 2- 4 times a day

Refer patient

Post-renal AKI
  • Urgent catheterization
  • Refer to tertiary facility

NON-PHARMACOLOGICAL 

  • Avoid nephrotoxins
  • Adjust the doses of renally excreted drugs (penicillin, amoxicillin, cotrimoxazole, ciprofloxacin)
  • Nutrition
    • Low salt diet
    • Low potassium diet (no bananas, tomatoes, unboiled potatoes, citrus fruits)
    • High caloric diet
    • Breastfeeding can be continued

Complications

  • Chronic kidney disease
  • Pulmonary oedema
  • Uraemic encephalopathy
  • Bleeding diapthesis

Referral

All patients with AKI

TREATMENT IN ADULTS

Objectives 

  • Assess the hydration status of the patient
  • Patients who are dehydrated will need fluid resuscitation
  • Avoid Ringer's Lactate fluids (has high potassium content)
  • Patients who are fluid overloaded will need fluid restriction and/or diuretics
  • Restrict salt intake
  • Weigh the patient daily
  • Carefully monitor fluid intake and output on a chart Medical rehabilitation for cardiorespiratory rehabilitation. 
  • Reduce the rate of rise of urea:
    • Give adequate calories
    • Restrict protein in the diet
    • Treat hyperkalaemia:
      • Restrict potassium intake by restricting fruits, vegetables, meat and feezy drinks
      • If potassium is > 6.5mmol/l give Insulin 10 Units in 50ml of 50%Dextrose infusion over 30 minutes
      • Give a Potassium Binding Resin 30-60g orally
  • Refer patient to Central Hospital for further management and consideration for dialysis if not responding to measures above

Indications for dialysis include:

  • Hyperkalaemia refractory to insulin shifting
  • Fluid overload not responsive to diuresis
  • Metabolic acidosis
  • Pericarditis
  • Uremic symptoms and signs (encephalopathy, haemorrhagic pericardial effusion bleeding)
  • Lithium and theophylline overdose

Note:

  • Treat complications of renal failure such as convulsions, hypertension
  • Do an HIV and Hepatitis B test before referral for dialysis.