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

How do you approach this child ?
What are your principles of management ??
Would your approach be different if he was 37 years old ???

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.

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.

Reference.

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

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