Electrolyte management in the PICU

1. Electrolyte management in the PICU 2012

2. Goals • To discuss the pathophysiology of electrolyte disturbances • To review the acute management of electrolyte disturbances • To discuss 2 cases with audience participation

3. Case 1 • 13 yo male admitted to the PICU after crashing into a wall during a motorcross competition. • He is intubated with a current GCS of 6T and is receiving aggressive management for increased ICP’s. • Review head CT on next slide • On hospital day 2, his urine output increases to 10ml/kg/h.

5. Case 1 • HR 120 T 36 BP 110/62 98% on 50% FiO2 • CVP 2 • I/0 balance = -600 • What could be happening? • What labs would you send?

6. Case 1 • Differential diagnosis: • Post resuscitation diuresis • Polyuric ATN • Hyperglycemia/post-mannitol • Central Diabetes Insipidus • Cerebral salt wasting • Labs to send: • UA with spec grav • Urine osmolality, Urine sodium • Serum osmolality, Serum sodium • Basic metabolic panel

7. Case 1 • Na 158 K 4 BUN 25 Creat 0.7 Gluc 140 • Sosm 340 Uosm= 121 • UA sg 1.001 glucose negative • Una= 10 • Sum it up: • Hypernatremia + Hypovolemia + Increased DILUTE urine output

8. Case 1 • What other information would you want to know? • Types/amounts of IVF received over the last 24 hours • Whether mannitol or diuretics were given • What is the most likely diagnosis? • DI • How would you manage this patient? • Resuscitate with NS if needed • Fluid replacement with 1/2 or 1/4 NS • Vasopressin infusion titrated to UOP 3-4ml/kg/h

9. Case 1 • Your management strategy is effective and the patient’s UOP slows to 3-4ml/kg/hr. • On hospital day 4, previous therapies to adjust UOP have been discontinued. • The UOP continues to slow to <1ml/kg/hr.

10. Case 1 • T 36 HR 89 BP 118/72 CVP 12 • Na= 129, Serum Osm 277 BUN 10 • UA 1.025 Uosm=550 Una= 75 • Sum it up: • Hyponatremia + euvolemia + low UOP that is CONCENTRATED • What diagnoses would you consider? • SIADH, hythyroidism, glucocorticoid deficiency, psychogenic polydipsia, iatrogenic free water exces • How would you treat this? • Fluid restriction 30-50% maintenance • Avoid free water excess (use isotonic solutions)

11. Case 1 • On HD #6, despite fluid restriction and avoidance of excess free water, the sodium continues to trend down. UOP is 3-4ml/kg/hr. • Serum Na= 125 • Repeat UA = sg 1.015 Una= 250 • Sum it up: • Hyponatremia + euvolemia + high normal UOP that has A LOT of SODIUM • What could be happening? • Cerebral salt wasting

12. The body keeps your Posm between 280-290 mOsm/L…. Plasma osmolality thirst vasopressin Salt intake

13. Blood pressure/effective ECF vasopressin Renin-angiotensin thirst Atrial naturietic factor Symphathetic nervous system Salt intake

14. Hyponatremia

15. Hyponatremia: Clinical signs and symptoms • Nausea/vomiting • Lethargy • Headache • Confusion • Seizures • Non-cardiogenic pulmonary edema • These are mostly due to CNS dysfunction and cerebral edema!

16. Hyponatremia: Causes • Hypovolemia • Extra-renal sodium loss (Una<10) • Sweat, diarrhea, vomiting • 3rd spacing: trauma, burns, pancreatitis • Renal sodium loss (Una >20) • Diuretics • Mineralocorticoid deficiency • Cerebral salt wasting • Proximal type II RTA • Euvolemia (Una>20) • SIADH • Glucocorticoid deficiency • Hypothryoidism • Psychogenic polydipsia • Drugs: desmopressin, psychoactive agents, chemotx

17. Hyponatremia: Causes • Hypervolemia (Una<20) • Acute or chronic renal failure Una>20 • Congestive heart failure • Cirrhosis/hepatic failure • Nephrotic syndrome • Hyperosmolar • Hyperglycemia, mannitol, glycine

18. SIADH • Causes • Intracranial pathology, mechanical ventilation, post-operative, malignancy, neck surgery, pulmonary pathology • Diagnosis • Patient should be euvolemic • Labs: Serum osm, Urine osm, Una • Urine will be inappropriately concentrated for a patient who is hypoosmolar • Urine Na will be elevated and Urine output will be low • Treatment • 3% NS • Fluid restriction to 30-50% maintenance • Avoid excess free water-->make sure to check drips!

19. Hyponatremia: Therapy • Correct rapidly with 3% NS for severely symptomatic patients • 4ml/kg 3%NS will increase [Na] by 5 • Normalize sodium at a rate of 8-12 mEq/L over 24 hours with 0.45% or 0.9% NS • Central pontine myelinolysis • may be irreversible • dysarthria, dysphagia, spastic paresis, coma • Check frequent sodiums (q1 or q2h)

20. 3% NS • Characteristics • 513 mEq/L • pH= 5.0 • 1027 mosm/L • Can be administered peripherally (in the acute setting) or centrally (recommended) • 3-5 ml/kg will raise serum sodium by 4-6 mEq/L • Adverse effects • Metabolic acidosis and hyperchloremia • Venous irritation/phlebitis

21. Hypernatremia

22. Hypernatremia: Clinical signs and symptoms • Nausea/vomiting • Restless, irritable, or lethargic • Anorexia • Stupor/coma • Subarachnoid hemorrhage--Why?

23. Hypernatremia: Causes • Free water loss • Diuretics (loop) • Post obstructive diuresis • Acute and chronic renal disease • Sweating, fistula, burns, diarrhea, vomiting • Diabetes insipidus (central, nephrogenic) • Sodium gain • Hypertonic saline or sodium bicarbonate • TPN • Hyperaldosteronism • Cushing’s syndrome

24. Hypernatremia: Therapy • Risk of seizures and cerebral edema if corrected too rapidly • Correct hypovolemia with NS • Correct Na with 0.45% NS • Check Na frequently and adjust fluid therapy for a goal of 0.5-1mEq/L decrease qhour • Urine replacement (0.22% or 0.45% NS) • Vasopressin for central DI

25. Diabetes insipidus (central) • Causes • Surgical resection, trauma, tumor infiltration, genetic, • Diagnosis • Rising Na and Serum osmolality • low Uosm and low Urine sg • increased UOP • Treatment • Urine replacement with 1/2 or 1/4 NS • Vasopressin infusion: titrate to UOP 3-4ml/kg/h • Na checks every hour

27. Case 2

28. Case 2 • 15 yo male playing linebacker for high school football team presents in August with syncope, weakness, and palpitations. Bedside I-stat : 7.22/32/98/12/-9 Na 136 K 7 Gluc 189 iCa 0.7 • Cardiac monitors indicated the following:

29. Case 2 • What is this rhythm?

30. In case you were wondering, this is BAD!!!!

31. Case 2 • What electrolyte disturbances does this patient have? • Hyperkalemia • Metabolic acidosis • Hypocalcemia • What therapies would you initiate? • Calcium gluconate 100mg/kg • Sodium bicarbonate 1mEq/kg • Insulin 0.1 units/kg + D10 or D25 2ml/kg • Kayexalate PR • What other lab studies are needed? • BMP, Mg, Phos, Lactate, CK, Tox screen, Serum osmolality

32. Case 2 • HR 130 RR 28 BP 90/50 98% on 2L • Obese male, tachypneic, diaphoretic, able to talk, clear breath sounds, no murmur, thready pulses • Na 137 K 7.5 HCO3 12 BUN 28 Creat 1.6 Gluc 190 Ca 6 Mg 1.1 Phos 6 • CK 45000

33. Case 2 • Despite initial therapies, patient remains hyperkalemic • What would you do? • Continue to administer Na bicarb, insulin/glucose, Calcium gluconate • Place a hemodialysis catheter • Keep a defibrillator and hands-free pads nearby • What disease processes could cause this? • Acute renal failure • Tumor lysis syndrome • Rhabdomyolysis

34. Hypokalemia

35. Hypokalemia: Signs and symptoms • Generalized muscle weakness • Paralytic ileus • Cardiac arrhythmias • Atrial tachycardia • AV dissociation • EKG changes • Flat/inverted T waves • ST segment depression • U waves • Ascending paralysis and impaired respiratory function (K<2)

36. EKG in hypokalemia

37. Hypokalemia: Causes • Renal loss • Primary hyperaldosteronism, hypothermia, genetic syndromes (i.e. Liddle’s), type I and II RTA, drugs (I.e. amphotericin, foscarnet) • GI loss • Vomiting, diarrhea (VIPoma, enteric fistula, malabsorption, jejunoileal bypass) • Transcellular shift Alkalosis, beta agonists, caffeine, insulin, thryrotoxicosis, hypokalemic periodic paralysis

38. Hypokalemia: treatment • Determine the cause • When to correct? • How much? • 0.5-1 mEq/kg over 1 hour • What to use? • KCl po or IV • KPhos

39. Hyperkalemia

40. Hyperkalemia • Definition: K>6 mEq/L • Symptoms • EKG changes: peaked T waves, prolonged PR interval, widened QRS, V-fib • Muscle weakness/paresthesias

42. Hyperkalemia: Causes • Impaired excretion • Renal failure, mineralocorticoid deficiency, drugs, type IV RTA, • Iatrogenic • Transcellular shift • Acidosis, beta blockers, digitalis overdose, somatostatin • Other • Tumor lysis • rhabdomyolysis

43. Hyperkalemia: Treatment • Calcium gluconate • 100mg/kg IV peripheral or central • Insulin/glucose • Insulin 0.1units/kg IV • Glucose 2ml/kg D10 or D25 • The most effective way to quickly lower K!!! • Sodium bicarbonate • 1-2mEq/kg • Hemodialysis • Kayexalate • 1gram/kg po or PR

44. Ca, Mg, Phos

45. Calcium homeostasis

46. Hypocalcemia • Symptoms appear when iCa<0.7 • Symptoms include: • Neuromuscular irritability (tetany) • Paresthesias of hands/feet • Circumoral numbness • Laryngospasm or bronchospasm • Anxious/irritable/depressed/confused • Hypotension • Rickets • EKG changes include: • Prolonged QT • Non-specific ST-Twave changes

47. Hypocalcemia: Causes and Diagnosis • Determine the cause • PTH level • Vitamin D levels (25OHD3 and 1,25OHD3) • 24 hour urine calcium • Hypoparathyroidism • Irradiation, surgery, hypomagnesemia, DiGeorge, polyglandular autoimmune syndrome, storage disease, HIV • Vitamin D deficiency • Malnutrition, malabsorption, hepatobiliary disease, low sun exposure

48. Hypocalcemia: Causes • Calcium chelation/precipitation • Tumor lysis, rhabdomyolysis, citrate, foscarnet • Multifactorial • Sepsis, pancreatitis, burns

49. Hypocalcemia: Treatment • Calcium gluconate • 25-100mg/kg IV • Calcium chloride • 10-20 mg/kg IV • Must be given centrally • Treat low Magnesium • Treat underlying disease • When should you avoid treating hypocalcemia? • Tumor lysis syndrome (unless patient is symptomatic)

50. Hypomagnesemia: Symptoms • Symptoms: • Refractory hypocalcemia • Diarrhea • Ventricular arrhythmias • Muscle weakness, tremors, tetany • Causes • Decreased intake or malabsorption • Decreased renal reabsorption (familial, diuretics, amphotericin, bartters’s, gitelman’s • Transcellular shift (hyperaldosteronism, pancreatitis, respiratory alkalosis, catecholamines)