Electrolyte Abnormalities Flashcards

1
Q

Clinical features of HYPERnatremia

A
  1. AMS - lethargy, confusion, irritability
  2. Advanced neurologic deficit - coma, seizure
  3. Expanded intravascular volume
    • Pleural effusion, Ascities, Peripheral edema, HF
  4. C/o thirst or polyuria
  5. N/V
  6. Neuromuscular irritability - myoclonus, tremor/rigidity, hyperactive reflexes, weakness
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2
Q

DDx of HYPERnatremia: Uosm 700-800 mosmol/L

A
  1. Unreplaced insensible losses
  2. GI losses
  3. Na overload
  4. Deficit in thirst (rare)
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3
Q

DDx of HYPERnatremia: Uosm < 300 mosm/L

A

Diabetes insipidus

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4
Q

Tx of HYPERnatremia

A
  1. Determine volume status of patient
    a. Hypernatremia w/ Hypervolemia: Diuretics + HD
  2. Free H2O deficit = {(plasma Na/140) - 1} x kg x 0.6
    a. Goal Na less than or equal to 145
    b. Replace half free water deficit in 1st 24 hrs and remaineder in following 2-3 days
    c. Use 5% dextrose in water or 0.45% NaCl to correct deficit
    d. Monitor serum Na every 1-2 hrs
    * *rate of Na correction should NOT exceed 0.5 mEq/L per hour or 10-12 mEq/L per day
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5
Q

Tx of Central Diabetes Insipidus

A
  1. DDAVP
  2. Low Na diet
  3. Low-dose thiazide diuretic
  4. Carbamezapine (enhances vasopressin secretion
  5. NSAIDs
    • Impairs renal prostaglandin synthesis
    • Potentiates ADH action
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6
Q

Tx of Nephrogenic Diabetes Insipidus

A
  1. Tx underlying cause (eliminate effecting drug (lithium))
  2. Treat symptomatic polyuria
    • Low Na diet
    • Thiazide diuretic
    • Vasopressin and analog has no role in tx
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7
Q

What is the exact rate of correction (of HYPOnatremia) with hypertonic saline?

A
  1. 10 mEq/L in first 24 hours
  2. 20 mEq/L in first 48 hours
  3. In dire situations where serum Na is less than 105 mEq/L - correction is 1-2 mEq/L in first few hours using 3% hypertonic saline
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8
Q

S/s of HYPERkalemia

A
  1. Weakness, tingling, parasthesias
  2. Flaccid paralysis (primarily LE)
  3. Hypoventilation
  4. Metabolic Acidosis
  5. Cardiac toxicity
    a. usually precedes neurologic toxicity
    b. EKG changes
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9
Q

EKG changes for HYPERkalemia

A
  1. Increased T-wave amplitude (6-7 mEq/L)
  2. Flattened P wave, prolonged PR interval, widened QRS complex
  3. AV conduction delay
  4. Loss of P wave
  5. V Fib and Asystole (10-12 mEq/L)
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10
Q

Tx of HYPERkalemia

A
  1. Protect myocardium - CaCl
  2. Sodium Bicarb 50 mEq IV
  3. Insulin + D50 IV
  4. Albuterol
  5. Loop/Thiazide Diuretics
  6. Promote GI loss w/ cation exchange resins
  7. Hyperventilate (if intubated)
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11
Q

S/s of HYPOkalemia

A

K < 3 mEq/L

  • Fatigue
  • Myalgia
  • Muscle weakness in proximal LE
  • Constipation and intestinal ileum
  • Glucose intolerance
  • EKG: flattened/inverted T-waves, Prominent U wave, ST depression, Prolonged QT

K < 2 mEq/L

  • Progressive weakness
  • Hypoventilation
  • Complete paralysis
  • Increased risk of rhabdomyolysis
  • EKG: Prolonged PR, Decreased voltage, Widening QRS, Increased risk of Ventricular arrhythmia
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12
Q

Causes of HYPOcalcemia

A
  1. PTH deficiency (gland removed, severe hypomagnesemia, burns, sepsis, pancreatitis)
  2. Vit D deficiency
  3. Hyperphosphatemia (renal failure, tumor lysis, rhabdo)
  4. Renal failure
  5. Citrate toxicity
  6. Acute alkalemia
  7. Post-cardiopulmonary bypass
  8. Acute pancreatitis
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13
Q

S/s of HYPOcalcemia

A
  1. CV
    • ECG changes: QT prolongation, heart block
    • Heart Failure
    • Hypotension
    • Digitalis insensitivity
    • Impaired beta agonist action
  2. Tetany (Chvostek/Trousseau’s sign)
  3. Muscle spasm
  4. Pappilledema
  5. Seizures
  6. Irritability/Mental Status changes
  7. Apnea
  8. Laryngeal spasm (stridor after thyroidectomy)
  9. Bronchospasm
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14
Q

Indications for Mg Therapy

A
  1. Premature labor: Tocolysis
  2. Pre-eclampsia and eclampsia
  3. Tetanus and pheochromocytoma
  4. Cardiology
    • Improves myocardial oxygen demand
    • Reduces incidence of dysrhythmias in post-MI and CHF
    • Tx for Torsades de Pointes
  5. Respiratory
    • Asthma management - smooth muscle relaxation in bronchioles
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15
Q

S/s Mg Toxicity: Mg level 5-7 mg/dL

A
  • Lethargy
  • Drowsiness
  • Flushing
  • Nausea
  • Vomiting
  • Diminished deep tendon reflexes
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16
Q

S/s Mg Toxicity: Mg level 7-12 mg/dL

A

CV

  • Hypotension: direct vasodilation
  • Dysrhythmias
  • Increased QRS duration
  • Prolonged PR and QT interval
  • Depressed myocardial performance

Neuromuscular

  • Antagonizes release and effect of ACh at NMJ
  • Potentiates action of depolarizing and non-depolarizing NMBs
  • May potentiate severe muscle weakness in MG or Eaton-Lambert

Resp:

  • Depressed respiration and apnea
  • Bronchiodilator effect
17
Q

S/s Mg Toxicity: Mg level > 12 mg/dL

A
  • Hypotension
  • Bradycardia
  • Diffuse vasodilation
  • Paralysis
  • Coma
  • Significant respiratory depression
  • Complete Heart Block
  • Cardiac arrest
18
Q

Tx of Hypermagnesemia

A
  1. Stop or treat underlying cause
  2. Forced diuresis with saline followed by loop diuretic
  3. IV Calcium
  4. Hemodialysis