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Organ System Issues and Specific Diseases Commonly Encountered in the PICU A. Endocrine Diabetic Ketoacidosis Definition: 1. Metabolic acidosis 2. Ketonuria/ketonemia 3. Hyperglycemia (not mandatory) 4. Dehydration 5. Associated electrolyte disturbances: psuedohyponatremia, hypokalemia, hypophosphatemia PICU admission criteria: (depends on case/attending) 1. PH<7.25, HCO3 <15, mental status changes, cardiac arrhythmia 2. Insulin infusion that requires titration Pathophysiology: 1. Occurs due to an absolute or relative insulin deficiency along with an excess of counter regulatory hormones (e.g. glucagon, catecholamines, cortisol, and growth hormone) as seen with infection or stress results in stimulation of lipolysis and increased levels of circulatory free fatty acids 2. Fatty acids are oxidized in liver resulting in elevated levels of circulating ketone bodies (beta-hydroxybutyrate and acetoacetate) 3. Counter regulatory hormones stimulate hepatic ketogenesis as well as gluconeogenesis and glycogenolysis resulting in excess glucose production and hyperglycemia 4. DKA can occasionally present without hyperglycemia such as during pregnancy, in patients who have been partially treated and those with prolonged vomiting with little to no carbohydrate intake as blood glucose rises, the ability of the proximal tubule to resorb glucose is exceeded and glycosuria occurs resulting in osmotic diuresis and dehydration Evaluation: 1. Careful history: vomiting, abdominal pain, polyuria, polydipsia, nocturia, weakness, heavy breathing or shortness of breath, symptoms of intercurrent illness, mental status changes, sweet odor to breath, weight loss 2. Physical exam: dehydration (dry mucous membranes, poor skin turgor, poor perfusion), tachycardia, hypotension, Kussmaul respirations, somnolence, hypothermia, impaired consciousness 3. Laboratory studies: - venous blood gas - metabolic panel/blood glucose - urine or serum ketones - complete blood count - anion gap - consider: HgA1C, TSH, freeT4 - other signs of infection i.e. urinalysis/culture Useful Equations: 1. Correction for psuedo/dilutional hyponatremia: Na+ (corrected) = Na+ (measured) + [(serum glucose – 100)/100] x 1.6 2. Anion gap: [(Na+ + K+) – (HCO3- + Cl-)] Treatment: 1. ABC’s Æ ensure adequate airway, ventilation and circulation 2. Correct fluid deficits - calculate fluid deficit (may assume 5-10% dehydration) - i.e., total fluid deficit = 10ml/kg for each 1% dehydrated - consider administering a 10-20 ml/kg bolus NS over 1 hour - replace evenly over 48 hours in addition to maintenance fluids 3. Correct electrolyte deficiencies - consider normal saline or 1/2 normal saline - potassium shifts extracellularly due to acidosis- therefore despite normal - serum potassium levels a total body deficit usually exists - if serum K < 5, replace with 40 mEq potassium in fluids initially.
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