Diabetic ketoacidosis

Background

• Hyperglycemia
  • Leads to osmotic diuresis
    • Loss of fluid, Na, Cl, K, Phos, Ca, Mg
• Acidosis
  • Due to lipolysis / loss of ketoanions
  • Causes respiratory alkalosis
  • Breakdown of adipose > prostaglandin I2, E2
    • Prostaglandins + acidosis = vasodilation
    • Prostaglandins cause N/V/abd pain
• Dehydration
  • Causes Renin system activation
    • K and ketoanion loss (in exchange for chloride)
      • Worsens metabolic acidosis

Causes

• • Insulin non-compliance
  • Infection
  • Ischemia
  • Intra-abd process
  • Meds
    • Steroids, antipsychotics, thiazides
  • ETOH/drug abuse
  • Pregnancy
  • Hyperthyroidism
  • GI hemorrhage

Classification

• Diagnosis = BS >250, AG >10, bicarb <15, pH <7.3, mod ketones
  • BS may be lower if impaired gluconeogenesis (liver failure)
  • Bicarb may be normal if concurrent alkalosis (e.g. vomiting)
    • In this case an elevated gap may be the only clue
• Severity
  • Mild (ketosis): gap <12
  • Mod: gap 12-18
  • Severe: gap >18

Workup

• CBC
• Chem 10
• UA
• Serum ketones
• hCG
• ECG
• VBG
  • Venous pH ~ 0.03 lower than arterial pH
  • Verify that respiratory compensation is as expected
• CXR

Treatment

• Volume then potassium then insulin

Labs

• Glucose check Q1hr
• Chem 10 Q4hr
• Corrected Na:
  • Add 1.6 for each glucose of 100 >100

Fluids

• Most pts 3-6L depleted
• If severe hypovolemia: 1L NS/hr for up to 3 hr
• If mild dehydration then evaluate corrected Na+
  • If hypernatremic: 1/2NS @ 250-500ml/hr
  • If hyponatremic: NS @ 250-500ml/hr
• When BS < 200 switch to D51/2NS@ 150-200 ml/hr(+/- KCl)
• Bolus NS as needed for unstable VS

Insulin

• Check K prior to insulin Tx!
  • If K < 3.3 do not administer insulin
• IV Route
  • IV gtt 0.14 U/kg/hr = 10 U/hr in 70kg pt
    • Bolus dose unnecessary
  • If BS does not decrease by 50-70/hr then double infusion rate qhr until achieved
  • When BS <200, reduce to 0.02-0.05 U/kg/hr IV OR give subQ 0.1 U/kg q2hr
    • Maintain BS between 150 and 200 until resolution of DKA
• SubQ route (appropriate only for mild DKA)
  • Insulin lispro or aspart 0.3 U/kg initially
    • 0.2 U/kg one hr later
      • 0.2 U/kg q2hr thereafter
  • If BS does not decrease by 50-70/hr then double dose qhr until achieved

Potassium (initial)

• Ensure adequate urine output before giving K
• >5.5: don't give, but recheck q2hr
• 3.3-5.5: give 30 meq/hr in each liter bag
  • 1/2NS is preferred b/c adding 30meq to NS = hypertonic soln
• <3.3: hold insulin and give 30 meq/hr until K >3.3

Bicarb

• if pH <6.9: 100 meq NaHCO3 in 400mL H2O @ 200 mL/hr
  • Dose as needed until pH > 7.00

Phosphate

• Repletion is controversial
  • Hypophosphatemia following insulin tx usually asymptomatic
    1. Repletion is associated with hypoCa and hypoMg
• Consider repletion (KPO4 20-30 meq/L)if:
  • Phosphate <1.0
  • Cardiac dysfunction
  • Respiratory dysfunction
  • Evidence of hemolysis or rhabdo

Secondary

• When gap closes and patient able to eat:
  • Begin multidose insulin regimen
  • Continue IV infusion for 1-2 hr after SC insulin tx is begun

Complications

• Cerebral Edema
  • Almost all affected pts are <20yrs
  • Associated with initial bicarb, not rate of glucose drop
• Noncardiogenic pulmonary edema

Sliding Scale

• 200-250 = 4u sq
• 251-300 = 6
• 301-350 = 8
• 351-400 = 10

Source

Adapted from Chavira, Rosen, Mistry, Ip, Donaldson, Pani, UpToDate