AFTB Lecture Notes - Diabetic Ketoacidosis

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AFTB Lecture Notes - Diabetic Ketoacidosis

Oct 12th, 2008 by sandnsurf

EPIDEMIOLOGY

* New diagnosis of diabetes 10-27%
* Infection ~ 35%, inadequate insulin ~ 30%, surgery, trauma, alcohol, cocaine and drugs such as steroids, thiazides, sympathomimetics.
* No cause found in 19-38%.
* Mortality < 5%. Under 2% in young adults, but > 20% if over 65 years.
* Also high > 15% in patients with hyperglycaemic, hyperosmolar non-ketotic syndrome (HHNS), when BSL usually > 50 mmol/L, and osmolality is > 320 mosm/L - can calculate latter by (2[NA + K] + glucose).

DIAGNOSTIC CRITERIA

* Raised glucose >11.1 mmol/L
* Acidosis with arterial pH < 7.3, or venous bicarb < 15 mmol/L
* Ketonuria (urinalysis may miss 3-hydroxybutyric acid early on); or ketonaemia

MANAGEMENT/COMPLICATIONS

* Hypoperfusion
o Rapid initial crystalloid, especially for significant circulatory insufficiency, at 15-20 mL/kg in first hour ie. 1-1.5 L.
o Possible role for bicarbonate is in patients with impending cardiovascular collapse, if pH < 6.9. Dilute 100 mmol 8.4% bicarbonate in 250-1000 mL 0.45% NS, and give over 30-60 minutes with 20 mmol K via infusion pump. (Note there are no prospective data concerning bicarbonate use below pH 6.9, and from 6.9-7.1 morbidity and mortality outcomes are equivocal ie. not proven).
* Fluid replacement
o Total body water deficit 100 mL/kg, and sodium deficit 7-10 mmol/kg.
o Restore normal hydration with 0.9% NS at 4-14 mL/kg/hr, to correct estimated fluid deficit over first 24 hours, without exceeding change in osmolality greater than 3 mOsm/kg per hour.
o One regime is NS 1000 mL in first hour, 500 mL/hr next 4 hours, then 250 mL/hr next 4 hours ie. around 4 L in first 9 hours.
o Aim to restore fluid deficits over 24 hours in adults, or up to 48 hours in children.

Dhatariya K. Diabetic ketoacidosis. BMJ 2007;334:1284-5. [Reference]

* Insulin infusion
o Insulin infusion at 0.1 units/kg/hr (ie. 5-7 units/hr) short-acting insulin, until BSL < 15 mmol/L, then drop to 3 units/hr.
o IV bolus short-acting insulin 0.15 units/kg unnecessary.
* Hypokalaemia
o Total body deficit 3-5 mmol/kg. Give 10-30 mmol K+ per L fluid, as soon as it is known serum K+ level is below 5.0 mmol/L, and urine output is established.
o Give 40 mmol per L fluid if K+ < 3.5 mmol/L, but must use infusion pump for fluid.
* Hypoglycaemia
o Adjust insulin rate to drop sugar roughly 5 mmol/L per hour. Avoid BSL dropping below 15 mmol/L.
o Change to 5% dextrose if BSL < 15 mmol/L, but continue insulin until ketoacids are cleared.
* Hyperchloraemic acidosis
o Usually related to fluid therapy, but is mild and transient.
o Change to 1/2 NS (0.45%) if Na > 150 mmol/L. (Remember corrected serum Na level is higher than measured. Add 1 mmol/L to [Na] for each 3 mmol/L rise in BSL above normal).
* Hypophosphataemia / hypomagnesaemia
o Despite significant depletion up to 5-7 mmol/kg phosphate, and 1-2 mEql/kg magnesium, which may not be reflected by serum levels, replacement of either does not appear to influence clinical course or outcome.
* Cerebral oedema
o Suspect if sudden headache with neurological deterioration ie. altered level of consciousness and lethargy, usually within 4-12 hours treatment onset (but can occur before initiation of therapy).
o 0.7 - 1% incidence, usually child / adolescent. Mortality up to 75% with significant neurological morbidity in 25%, once symptoms other than lethargy or behavioural change have occurred.
o Cerebral vasoconstriction with hypoxic ischaemia and disease severity implicated, plus possibly idiogenic osmoles (taurine, myoinositol) and defective Na/H ion exchange.
o Relates to a lower PaCO2 at presentation and higher initial serum urea; also smaller increases in serum Na+ and the use of bicarbonate.

Glaser N, Barnett P et al. Risk factors for cerebral edema in children with diabetic ketoacidosis. NEJM 2001; 344:264-269. [Reference]

*
o Rate of change of sugar level, and rates of fluid, sodium, or insulin delivery do not correlate with its occurrence ie. therapy is not responsible.

Hom J, Sinert R. Is fluid therapy associated with cerebral edema in children with diabetic ketoacidosis? Ann Emerg Med 2008;52:69-75. [Reference]

*
o Give mannitol 0.5 - 2.0 g/kg (2.5 - 10 mL/kg 20% mannitol) IV and supplemental oxygen; or consider 3% hypertonic saline 5-10 ml/kg over 30 min instead. Hyperventilation and or dexamethasone appear unhelpful.
* Thromboembolism
o Prophylactic low-dose heparin, especially older patients (or if hyperglycaemic, hyperosmolar non-ketotic (HHNS) syndrome).

Kitabchi A, Umpierrez G, Murphy M, Kreisberg R. Hyperglycemic crises in adult patients with diabetes. Diabetes Care 2006; 29: 2739-48. [Reference]
Savage M, Kilvert A (on behalf of Assoc British Clinical Diabetologists ABCD). ABCD Guidelines for the management of hyperglycaemic emergencies in adults. Practical Diabetes Int 2006; 23:227-31.
ESPE/LWPES consensus statement on diabetic ketoacidosis in children and adolescents. Arch Dis Child 2004;89:188-94 [or Pediatrics 2004; 113:e133-e140]. [Reference]
Stewart C. Diabetic emergencies: Diagnosis and management of hyperglycaemic disorders. Emergency Medicine Practice: An Evidence based Approach to Emergency Medicine 2004; 6(2): 1-24.