Acute renal failure in paediatrics (management and investigation)

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Objectives

The following guideline has been developed by clinicians within the Renal Unit at RHC Glasgow.

The objective of this guideline is to aid in the diagnosis, investigation and management or acute renal failure in children. It includes the management of fluid and electrolyte abnormalities in children with acute renal failure. 

Scope

This document is intended for use by clinicians in the Management and Investigation of Acute Renal Failure. For further information, contact a clinician within the Renal Unit. Ward office number 0141 452 4563

Definition of Acute Renal Failure
  • Oliguria - Urine Output: - <300ml/m2/day or 0.5ml/kg/hr
  • Anuria - Urine Output: - <1ml/kg/day
  • Hyperkalaemia - K >6.0 mmol/L on 2 separate occasions
  • Clinical Fluid Overload
  • Oedema
  • Triple rhythm
  • Hypertension

Paediatric-Modified RIFLE (pRIFLE) Criteria

Category Estimated CCl (eCCL) Urine Output
Risk eCCl decrease by 25% <0.5ml/kg/h for 8h
Injury eCCl decrease by 50% <0.5 ml/kg/h for 16h
Failure eCCl decrease by 75% or eCCL <35 ml/min/1.73 m2 <0.3 ml/kg/h for 24h or anuric for 12h
Loss Persistent failure >4 weeks  
End stage End-stage renal disease (persistent failure for >3 months)
Aetiology
Pre-Renal Intrinsic Renal Post-Renal

Hypovolaemia

Circulatory Insufficiency Posterior Urethral Valves

Peripheral vasodilatation

Nephrotoxins Blocked Catheter

Impaired Cardiac Output

"Renal Disease" Neurogenic Bladder

Renal Vessel occlusion

Myo/haemoglobinuria Trauma

Nephrotoxic Drugs*

Tumour infiltrate Calculi

Hepatorenal Syndrome

Intratubular obstruction  
Increased intraabdominal pressure Latrogenic Factors

 

*Avoid giving Ibuprofen

Clinical Assessment of Acute Renal Failure
  • Patient Weight – Required Daily
  • Urine Output
  • Blood Pressure
  • Hydration Status
  • Blood Biochemistry and FBC
  • Cardiorespiratory Examination
  • Neurological Examination
  • Musculoskeletal Examination
  • Bruising/Bleeding
  • Drug History Investigations
Investigations
- U&E’s, LFT’s and CRP             - LDH
- Uric acid - FENa
- Magnesium - Urinalysis
- Glucose - Urinary Sodium, Osmolality
- Osmolality - Microscopy for casts
- FBC ± Blood film - Culture and sensitivity
- Coagulation Screen - Renal Ultrasound
- Group and Save

Consider the following on clinical grounds

- Parathyroid hormone (if acute on chronic suspected)      - Serum for toxicology/ drug levels                                    
- C3 - Hepatitis Screen
- ASO titre, anti DNAse B - E. Coli Antibody
- Antinuclear antibodies/ anti-DNA binding - Stool culture
- Anti-GBM antibodies - AXR
- ANCA (anti neutrophil cytoplasmic antibody) - MCUG
- Blood culture - Isotope scan
  - XR left wrist and hand (signs of ROD in acute on chronic)        
  - Ophthalmology opinion
Urinary Electrolytes in Acute Renal Failure
  Pre-renal Intrinsic Post-renal
Urine Output Oliguria Oliguria - Polyuria Variable
Uosm (mosm)
(newborn)
>500
(>350)
<300 
(<300)
<350
(<300)

 

UNa (mmol/L) 
(newborn)

<10
(31±19)

>40
(63±35)

>40

FENa (%) 
(newborn)
<1
(<2.5)
>2
(>3)
<2 
(<3)

 

Lab studies Increased Urea 
Lower Creatinine
Hypocalcaemia
Hyperphosphataemia
Creatinine increases 
by 45 –130 mmol/L/day
Hyponatraemia
Hyperkalaemia 
Hyperchloraemic 
Acidosis

For calculation of FENa- http://www.mdcalc.com/fractional-excretion-of-sodium-fena/

Management of Acute Renal Failure

Fluid Management

  • Correction of Hypovolaemia
  • Fluid Overload (Red Flag):
    • Furosemide 2 - 5mg/kg over 1 hour
    • Fluid restriction
    • Minimalise drug infusion volumes
    • Accurate input/output
    • Daily weight
    • Dialysis 
  • Beware Polyuria 

Aim is to maintain isovolaemia erring on the side of minimal fluid overload.

As a rule of thumb, daily fluid requirements should equal insensible fluid losses plus output (urine, vomiting, drain losses, diarrhoea etc). Insensible fluid losses can be calculated as per the table below: 

Weight                 Insensible Fluid Loss
1-10kg

25ml/kg

10-20kg

12.5ml/kg

>20kg

5ml/kg

Electrolyte Abnormalities

Hyponatraemia

  • Salt loss > water loss 
    • Volume resuscitation
    • Sodium deficit (140-Na) x 0.65 x Body weight
    • Replace deficit with 0.9% saline, usual maintenance
  • Water gain > Na
    • Fluid restriction
    • Hypertonic saline with loop diuretic
    • Mannitol

Hypernatraemia

Hypernatraemia may be due to:

  • Extrarenal fluid loss in PICU patients
  • Excess sodium bicarbonate
  • Volume resuscitation
  • Water deficit 
    - weight x 0.65 x ((Actual Na/140)-1))
    - Replace with 0.45% saline over 36-72 hrs
  • Central DI- DDAVP
  • Nephrogenic DI- Diuretic therapy

Hypocalcaemia

  • Emergency- 0.5ml/kg/hr of 10% Ca Gluconate
  • 50ml/kg Ca/kg/day
  • If resistant, check Mg

Hyperphosphataemia

  • Phosphate restriction
  • Phosphate binders e.g. Ca Carbonate

Hypophosphataemia

  • Polyuric states

Hyperkalaemia

Acid–Base Disorders

These are invariably acidosis and are often mixed respiratory and metabolic especially in the intensive care setting. Treatment is generally only indicated if there is associated hyperkalaemia or if the acidosis is profound. 

Treatment of Acid-Base Disorders

  • Base Deficit (mmol) = Base Excess x Weight/3
  • Replace half of the deficit initially
  • Sodium Bicarbonate is hypertonic with a risk of CNS complications or hypernatraemia and is only effective with adequate ventilation.
  • Rapid correction of acidosis may cause hypocalcaemia and tetany or seizures
  • Therefore rapid correction to be avoided
Nutrition in Acute Renal Failure

Acute renal failure is a hypercatabolic state and requires aggressive nutritional support. Unlike adults there is no indication for dietary protein restriction, which should be delivered in amino acids or protein of high biological value. The majority of calories should however be delivered as carbohydrates. 

  • Calories 1400 kcal/m2/day
  • Protein 0.6g/kg/day (1.5g if dialysed)
  • Intralipid - medium chain triglycerides
  • Folate and Vitamin supplementation
Hypertension in Acute Renal Failure

May relate solely to salt and water overload and therefore in the presence of oligo/anuria and in the absence of hypovolaemia an initial trial of diuretic therapy is justified.

For further details of the management and investigation of hypertension – see appropriate protocol.

Drug therapy for the emergency treatment of hypertension is outlined below.

Agent Dose Onset Action Complications
Labetalol 1-5 mg/kg/hr 3-5 min  Alpha & beta Blocker Hypoglycaemia 
Well tolerated
Nifedipine 0.25-0.5 mg/kg sublingual 5-10 min Ca channel blocker

Headache,
nausea,
syncope

Sodium Nitroprusside 0.5-8 ug/kg/min as IV infusion Instant Direct vasodilator Thiocyanate poisoning
Clonidine 2-6 ug/kg ~10 min Central alpha 2 Agonist    Depression
Rebound
Hydralazine 0.2 to 15mg/dose IV bolus 
4-6ug/kg/min IVI 
5-10 min Direct vasodilator Headache,
vomiting,
tachycardia
Frusemide

1-3mg/kg over 15min 
0.1-1mg/kg/hr IVI

  Diuretic

Volume depletion, 
electrolyte abnormalities

References

http://www.infokid.org.uk/

Royal College of Physicians of Edinburgh. Acute kidney injury app

Editorial Information

Last reviewed: 30 September 2017

Next review: 01 October 2020

Author(s): Ian Ramage

Approved By: Clinical Effectiveness