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Metabolic Abnormalities

Metabolic Abnormalities. Surgical Fundamentals Lecture Asha Bale, MD 8/06/10. Overview. Symptoms, Etiology, Treatment Sodium Potassium Magnesium Calcium Glucose abnormalities Arrhythmias. Hyponatremia Na<136. Most Common causes are Iatrogenic or SIADH Sx: CNS (increased ICP)

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Metabolic Abnormalities

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  1. Metabolic Abnormalities Surgical Fundamentals Lecture Asha Bale, MD 8/06/10

  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 (vomitting, 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<15, UOsm >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 EKGPeaked t wavesFlattened p waveProlonged PR intervalWidened QRS complexSine wave formationV-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, vomiting, 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 • arrhythmias

  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% Ca Chloride • Give slowly over several minutes • Can worsen HTN or Dig toxicity • Correct associated deficits in magnesium, potassium and pH

  36. HyperphosphatemiaSerum 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. Hypophsphatemia • 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. Arrythmias • 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

  40. Arrhythmia

  41. Arrhythmia= A-Fib

  42. Arrhythmia

  43. Arrhythmia = SVT

  44. Arrhythmia

  45. Arrhythmia= V-Tach

  46. Arrhythmia

  47. Arrhythmia

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