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sweet & sour…

The case.

A 7 year old boy presents to your ED with a 3-4 day history of fevers, nausea and vomiting. There is some associated non-specific abdominal pain. He has a history of Type 1 Diabetes Mellitus. His blood glucose at triage is reading ‘HI’ and his finger-prick ketones are 6.4 mmol/L. He is therefore taken through to your resus bay, where you achieve IV access and get the following set of results…

BloodGas

EUCs

 

[DDET How do you approach this child ?]

Well, there are no hidden tricks with this case. This is not a fancy diagnosis, rather a very common one. I feel that if you are in a department that sees children, then you need to know Paediatric DKA back to front & be able to manage it with a certain level of finesse, particularly as there is certainly the potential to do more harm than good.

[/DDET]

[DDET What are your principles of management?]

Management of Paediatric DKA.

I wanted to use this case as a vignette to bring the following paper to your attention….

ISPADpaper

To my knowledge it is the most concise paper that summarises the management of Paediatric DKA. Below are what I consider the pertinent points to take from this guideline…

Diagnosis:

    • * Hyperglycaemia 
           - Blood glucose > 11mmol/L (200mg/dL)
      * Venous pH < 7.3 or HCO3 < 15mmol/L
      * Ketonaemia / Ketonuria.

Severity:

    • * Mild
           - pH < 7.3  or  HCO3 < 15 mmol/L
      * Moderate
           - pH < 7.2  or  HCO3 < 10 mmol/L
      * Severe  
           - pH < 7.1  or  HCO3 < 5 mmol/L

Goals of Therapy:

    • * Correct dehydration.
      * Correct acidosis & reverse ketosis.
      * Restore blood glucose to near normal.
      * Avoid complications of therapy.
      * Identify & treat any precipitating causes.

Fluid Management:

    • * Severe volume depletion w/out shock.
           - Volume resuscitation begins immediately w/ 0.9% saline.
           - Aim for 10mL/kg/hr over 1-2 hours
                ~ repeat if necessary.
           - Do not exceed 30mL/kg in first 4 hours.
      
      * DKA w/ shock (rare).
           - 20mL/kg bolus (0.9% Saline or Hartman's) 
           - reassess after each bolus
           - don't forget the intraosseous route !
      
      * Subsequent fluid management (deficit replacement).
           - 0.9% Saline or Hartman's for at least 4-6 hours.
                ~ Thereafter; tonicity > 0.45% (w/ added K+)
           - Calculate fluid deficit (ie. 5 vs 7 vs 10% dehydration).
                ~ Rehydrate evenly over 48 hours
                ~ Avoid rates of > 1.5-2x usual daily maintenance requirements.
                ~ click here for fluid calculation example
           - No need to add urinary losses to fluid calculations.
           - Sodium content may need to be increased 
             (if Na+ not increasing w/ appropriate therapy).

Insulin Therapy:

    • * Start insulin infusion 1-2 hours after commencing fluid replacement.
           - ie. after initial volume expansion.
      * Dose = 0.1 units / kg / hour (via infusion).
           - reduce to 0.05 units/kg/hr in those w/ exquisite insulin sensitivity.
           - do not use boluses !!
      * Continue insulin until DKA resolves [ Target BSL ~ 11mmol/L ].
           - ie. pH > 7.3, HCO3 > 15 mmol/ or anion gap is closed.
      * Add 5% Dextrose to IV fluid when glucose ~ 14-17mmol/L
           - consider adding earlier w/ rapid glucose drop (>5mmol/hr).
           - up to 10-12.5% may be required to correct acidosis.

Potassium Replacement:

    • * Children w/ DKA have total body deficits of up to 3-6 mmol/kg.
      * Replacement is required regardless of serum K+ concentration.
           - If hypokalaemic;
                ~ start K+ replacement w/ initial volume expansions.
                ~ concentration of 20mmol/L should be used.
           - If normal K+;
                ~ start K+ replacement after expansion, before insulin therapy.
           - If hyperkalaemic;
                ~ defer K+ replacement until urine output is documented.
      
      * Maintenance therapy;
           - Potassium concentration of 40mmol/L.
      * Maximum replacement is ~ 0.5mmol/kg/hr.
      

Phosphate Replacement:

    • * No clinical benefit from routine replacement.
      * Severe hypophosphataemia w/ unexplained weakness should be treated.
      * Potassium phosphate can be used with KCl to replace both.
           - Beware inducing hypocalcaemia.

Acidosis:

    • * Severe acidosis is reversible by fluid & insulin therapy.
           - Insulin stops further ketoacid production & generates bicarbonate.
      * No clinical benefit from bicarbonate administration.
           - May cause paradoxical CNS acidosis.
      * Consider bicarbonate use in;
           - severe acidosis (pH < 6.9) w/ decreased cardiac contractility 
             & vasodilatation 
           - life threatening hyperkalaemia.

Cerebral Oedema:

    • * Responsible for 60-90% of all DKA-related deaths.
      * Incidence ~ 0.5-0.9% of DKA cases.
      * Mortality ~ 21-24%.
      
      * Risk Factors:
           - younger age / New onset diabetes / longer duration of symptoms
           - greater hypocapnia (adjusted for severity of acidosis)
           - more severe acidosis
           - increased serum urea
           - bicarbonate therapy (to correct acidosis)
           - greater volumes of fluid given in first 4 hours
           - attenuated rise in serum sodium concentration (despite therapy)
           - administration of insulin in first hour of fluid therapy
      
      * Signs & Symptoms:
           - Headache / progressive bradycardia or hypertension
           - Altered neurological status
                ~ restlessness
                ~ irritability
                ~ drowsiness
                ~ incontinence 
           - Focal neurological signs (eg. cranial nerve palsies)
           - Decreased oxygen saturations.
      
      * Treatment:
           - Elevate head of bed
           - Reduce IV fluids to 1/3 the rate
           - Mannitol:
                ~ 0.5-1.0 grams/kg over 20 minutes.
                ~ repeat if no response in 30-120 minutes.
           - Hypertonic (3%) saline.
                ~ an alternative to mannitol
                ~ 5-10mL/kg over 30 minutes.
           - Intubation. Avoid aggressive hyperventilation.
           - CNS imaging (CT-Brain); 
                ~ confirming diagnosis/assessing for alternate diagnoses.

[/DDET]

[DDET References]

Reference.

  1. Wolfsdorf, J. et al. Diabetic ketoacidosis in children and adolescents with diabetesPediatric Diabetes. 2009. 10 Suppl 12: 118–133.

 

[/DDET]

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