1. Metabolic Abnormalities Asha Bale, MD Surgical Fundamentals Lecture #6

2. Overview Symptoms, Etiology, Treatment Sodium Potassium Magnesium Calcium Glucose abnormalities Arrhythmias

3. Hyponatremia Na<136 Most Common causes are Iatrogenic or SIADH Sx: CNS (increased ICP) Sx usually don’t occur until Na<120 Causes: –Na depletion (extracellular volume deficit) –Na dilution (Excess extracellular water) –Excess solute relative to free water (ie: hyperglycemia) –Pseudohyponatremia

4. Na depletion Decreased intake –Low sodium diet –Enteral feeds Loss of Na containing fluids –GI losses (vomiting, NGT, diarrhea) –Renal losses (diuretics or primary renal disease)

5. Na Dilution Excess extracellular water/Excess extracellular volume –Iatrogenic (IVF, free water) –High ADH (increases reabsorption of free water, causing increase in volume and hypoNa) SIADH- low serum Na, high Urine Na and U Osm –Drugs causing water retention Antipsychotics, tricylcic antidepressants, ACE inhibitors

6. Excess solute causing HypoNa Excess solute relative to free water can cause hyponatremia –Untreated hyperglycemia Glucose causes an osmotic force, shifting water from the Intracellular compartment to the Extracellular compartment (like dilutional hypoNa) For every 100mg/dl increase in Glu, plasma Na decreased by 1.6 –Mannitol

7. Pseudohyponatremia Extreme elevations in plasma lipids and proteins No true decrease in extracellular sodium relative to water

8. Hyponatremia Algorithm Symptomatic or Asymptomatic? Asymptomatic –Hypotonic (POsm<280) Hypervolemic- water restriction, diuresis Hypovolemic- isotonic saline Isovolemic- water restriction –Isotonic (POsm 280-285, hyperlipidemia) Correct underlying disorder –Hypertonic (POsm>280, hyperglycemia, hypertonic infusions like mannitol) Correct underlying disorder Symptomatic (treat aggressively) –3% NaCl –Don’t correct fast! –Stop when Na 120-125

9. Treatment of Hyponatremia Water deficit(L) = (serumNa-140 / 140) x TBW –TBW estimated as 50% of lean body mass in men and 40% in women Don’t correct faster than 1mEq/h and 12mEq/d, avoids cerebral edema and herniation Frequent neurologic exams

10. Treatment of Hyponatremia Most cases- Free water restriction, if severe- administer sodium If Neuro Sx, then use 3% NS to increase Na by no more than 1mEq/L per hour until Na level reaches 130, or Neuro Sx are inproved Rapid correction causes pontine myelinosis, seizures, death

11. Hypernatremia Na>144 mEq/L Caused by loss of water or a gain in Na in excess of water (hypervolemic, isovolemic, hypovolemic) Can be assoc with increased, normal or decreased extracellular volume Water shifts from ICF to ECF, causing cellular dehydration Sx (neurologic): restlessness, irritability, seizures, coma, death

12. Hypervolemic Hypernatremia (Gain of water and salt) Iatrogenic –Administration of Na containing fluids, including Na bicarb Mineralocorticoid excess –U Na>20meq/L, Uosm>300mOsm/L –Hyperaldosteronism –Cushing’s Syndrome –Congenital Adrenal Hyperplasia

13. Normovolemic Hypernatremia (Loss of water) Nonrenal Causes of water loss –GI –Skin Renal Causes of water loss –Diabetes Insipidus –Diuretics –Renal Disease

14. Hypovolemic Hypernatremia (Loss of water and salt) Renal water loss –DI (Low ADH) (high Serum Na, dilute urine, low U Na and U Osm) –Osmotic diuretics –Adrenal failure –Renal tubular diseases (UNa<20, UOsm<300-400) Nonrenal water loss (GI, Skin) –UNa 400)

15. Hypernatremia Algorithm History, physical, electrolytes, BUN/Creatinine, Urine Na, UOsmolarity Assess extracellular volume status –Hypovolemic (Loss of water and Na) Restore extracellular volume, calculate water deficit Isotonic saline until euvolemic, then hypotonic saline or D5W to correct HyperNa –Isovolemic (Loss of water) D5W IV or water p.o. Diabetes Insipidus- Vasopressin –Hypervolemic (Gain of Na and water) Lasix and D5W or D51/4 NS If renal failure  dialysis

16. Hyperkalemia Normal K = 3.5 to 5.0 meq/L History, physical, EKG, chemistry, ABG Sx: GI (n/v, diarrhea), neuromuscular (weakness), cardiovascular (EKG changes, arrhythmias) EKG changes –Peaked t waves –Flattened p wave –Prolonged PR interval –Widened QRS complex –Sine wave formation –V-fib

17. Hyperkalemia EKG Peaked t waves Flattened p wave Prolonged PR interval Widened QRS complex Sine wave formation V-fib

18. Hyperkalemia Excess Potassium Intake –Oral, iv, blood transfusion Increased Release of K+ from cells –Cell destruction/breakdown –Hemolysis, rhabdomyolysis, crush injuries, gi hemorrhage, acidosis Impaired excretion by kidneys –Meds: K+ sparing diuretics, ACE Inhibitors, NSAIDs –Renal Insufficiency, Renal Failure

19. Treatment of Hyperkalemia Reduce total body K –Stop exogenous sources of K+ –Kayexalate (Cation-exchange resin, binds K in exchange for Na) PO or PR –Dialysis Shift K from extracellular to intracellular –Glucose/Insulin, bicarbonate –Albuterol Protect cells from effects of increased K –When EKG changes present, use Calcium chloride or calcium gluconate (5-10mL of 10% solution) Use cautiously in patients on Digoxin- can cause Dig toxicity

20. Hyperkalemia Algorithm History, PE, EKG, Chemistry, ABG K+<6.5, no EKG changes  –Stop supplemental K+ and repeat K+ K+<6.5, EKG changes  –Stop K+, Kayexalate or Lasix, look for underlying cause K+>6.5 or EKG changes  –Calcium gluconate, Glucose & Insulin, NaHCO3, Kayexalate, Lasix, Dialysis

21. Hypokalemia K+<3.5 mg/L Sx –Ileus, constipation –Weakness, fatigue –Cardiovascular EKG changes: u waves, t wave flattening, ST segment changes, arrhythmias

22. Etiology-Hypokalemia Inadequate intake –Dietary, K+ free IVF, TPN with inadequate K+ Excessive Renal Excretion –Hyperaldosteronism (waste K+) –Meds Diuretics which increase K+ excretion Penicillin (promotes renal tubular loss of K+) Loss in GI Secretions –Diarrhea, vomitting, high NGT outputs

23. Etiology- Hypokalemia Intracellular shifts –Metabolic Alkalosis K+ decreases by 0.3 meq/L for every 0.1 increase in pH above normal –Insulin therapy Drugs causing Magnesium depletion will cause K+ depletion as well –Amphotericin, aminoglycosides, foscarnet, cisplatin –Replace Magnesium!

24. Treatment of Hypokalemia Check K+, electrolytes, renal function and urine output Estimate for every 10 meQ K+ replaced, the serum potassium will increase by 0.1 mg/L Potassium repletion Oral (functioning GI tract, & mild, asymptomatic patients) –KCl, K-dur IV (Nonfunctioning GI tract, or severe hypokalemia) –No more than 20meq/H in an unmonitored setting –Can be up to 40meq/h replacement in monitored setting –Caution in patients with impaired renal function –Repeat K+ levels –KCl, KPhos

25. Magnesium Abnormalities Magnesium found in the intracellular compartment Of that found in the extracellular space, 1/3 is bound to albumin Normal 1.3 to 2.1 meQ/L

26. Hypermagnesemia Mg >2.2 mEq/L Rare Impaired renal function, excess intake with TPN, Excess use of laxatives or antacids Sx: n/v, weakness, lethargy, hypotension EKG changes: (similar to hyperkalemia) –Increase PR interval, widened QRS complex, elevated t-waves Tx: Ca 100-200mg IV over 5-10 mins., Dialysis, Remove Magnesium source

27. Hypomagnesemia Renal excretion –Alcoholism, diuretics, amphotericin B GI Losses –Diarrhea, malabsorption, acute pancreatitis, DKA, primary hyperaldosteronism Poor p.o. intake –Starvation, alcoholism, prolonged use of IVF, TPN

28. HypoMagnesemia Sx: neuromuscular and CNS hyperactivity, tremors, delerium, seizures Sx similar to hypercalcemia Associated with hypokalemia EKG: –Prolonged QT and PR intervals –ST segment depression –Flattened or inversion of p waves –Torsades de pointes –arrythmias

29. Torsades de Pointes- hypomagnesemia

30. Treatment of Hypomagnesemia Oral replacement if mild or asymptomatic –Magnesium Oxide IV replacement if severe (<1.0 mEq/L) or symptomatic –2g Magnesium sulfate IV over 5 minutes followed by 10g during the next 24 hours (if renal function is normal) If Torsades, give over 2 mins. Also correct hypocalcemia, frequently associated

31. Hypercalcemia Ca>10.5 Serum Ca above normal range of 8.5 to 10.5 mEq/L, or an increase in the ionized calcium level above 4.2 to 4.8 mg/dL Primary hyperparathyroidism (outpatient) Malignancy (inpatient) Sx: Neuro (confusion, depression), Musc (weakness, back pain), gi (n/v/ abd pain), cardiac, EKG changes

32. Hypocalcemia prolongs the QT interval by stretching out the ST segment. Hypercalcemia decreases the QT interval by shortening the ST segment so that the T wave seems to take off from the QRS complex

33. Treatment of Hypercalcemia Most cases due to malignancy, if not check PTH level –PTH high  hyperparathyroidism –PTH normal or low  w/u for malignancy Treatment is supportive, treat underlying cause Tx when symptomatic (Hypercalcemic crisis)(serum level >12mg/dL) Replete volume deficit, then brisk diuresis with normal saline and Lasix –1-2L NS over 1-2h, followed by 200-400mL/h with Lasix 20-80mg IV over 2-3h Etidronate, phosphate, mithramycin, steroids, calcitonin, Dialysis

34. Hypocalcemia Etiologies: pancreatitis, massive soft tissue infections, renal failure, pancreatic and SB fistulas, hypoparathyroidism, Magnesium abnormalities, tumor lysis syndrome Transiently after removal of a parathyroid adenoma Malignancies assoc w/ increased osteoclastic activity Massive blood transfusions (precipitation with citrate) Sx: parasthesias, muscle cramps, stridor, tetany, seizures

35. Treatment of hypocalcemia Check albumin, check for abnormalities of Phos and Mag Asymptomatic- give po or iv Chronic –Add Calcium to IVF –Calcium p.o. (1500 to 3000mg per day, plus vitamin D) Acute symptomatic: –Need to give 200 to 300mg of Calcium –20-30mL 10% Ca Gluconate OR –5-10mL 10%CaChloride –Give slowly over several minutes –Can worsen HTN or Dig toxicity –Correct associated deficits in magnesium, potassium and pH

36. Hyperphosphatemia Serum Phos >5mg/dL Normal 2.7 to 4.5 mg/dL Mostly seen in pt with renal failure Hypoparathyroidism Tx –Chronic- Low Phos diet, aluminum binding antacids –Acute- Dialysis

37. Hypophosphatemia Decreased intake Intracellular shift of phosphorus –alkalosis, insulin therapy Increased phosphorus excretion Sx: muscle weakness (important for vent dependent pts) PO- Nutraphos IV- NaPhos, KPhos

38. Arrhythmias Ask Desk Clerk to CALL Senior Resident and/or Attending! Symptomatic or Asymptomatic? ABC’s Code Cart into room, call Anesthesia if needed Vital signs, O2 Sat Quick History/Physical Exam EKG/Rhythm strip- Recognize the Arrhythmia Place on a monitor, Supplemental Oxygen ACLS Protocol- Stabilize Patient ABG or ABE, electrolytes, cardiac enzymes Treat Underlying Cause

39. Arrhythmia

41. Arrhythmia= A-Fib

42. Arrhythmia

43. Arrhythmia = SVT

44. Arrhythmia

45. Arrhythmia= V-Tach

46. Arrhythmia