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…
[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….
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:
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* Hyperglycaemia - Blood glucose > 11mmol/L (200mg/dL) * Venous pH < 7.3 or HCO3 < 15mmol/L * Ketonaemia / Ketonuria.
Severity:
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* 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:
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* Correct dehydration. * Correct acidosis & reverse ketosis. * Restore blood glucose to near normal. * Avoid complications of therapy. * Identify & treat any precipitating causes.
Fluid Management:
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* 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:
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* 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:
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* 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:
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* 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:
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* 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:
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* 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.
- Wolfsdorf, J. et al. Diabetic ketoacidosis in children and adolescents with diabetes. Pediatric Diabetes. 2009. 10 Suppl 12: 118–133.
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