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Electric-Lytes. Dr. Jeffrey P Schaefer General Internal Medicine. Objectives. Case based approach to abnormal Sodium Potassium Calcium Magnesium Phosphate. Sodium. Warm Up Case. 81 yr old female presents to ER recent viral illness vomiting and diarrhea Na 125 mmol/l.
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Electric-Lytes Dr. Jeffrey P Schaefer General Internal Medicine
Objectives • Case based approach to abnormal • Sodium • Potassium • Calcium • Magnesium • Phosphate
Warm Up Case • 81 yr old female presents to ER • recent viral illness • vomiting and diarrhea • Na 125 mmol/l
Hyponatremia • Neuromuscular Irritability • mild anorexia • headache • muscle cramps • irritability • delirium • coma • seizure • Rate of Reduction affects clinical severity
Common Causes • Edema • heart failure, nephrosis, cirrhosis • Water excess • SIADH, polydipsia, iatrogenesis • Volume Depletion • diuretics (esp thiazide), vomiting, diarrhea • Salt loss • adrenal insufficiency, hypoT4, • cerebral salt wasting • Shift (pseudohyponatremia) • hyperglycemia, hyperlipidemia
Case • 81 yr old female presents to ER • malaise • recent viral illness • vomiting and diarrhea Na = 125 mmol/l
Orders Solution? Volume? Rate(s)? Reassess? • Normal Saline • 1 – 4 l according to clinical assessment • 250 – 500 / hr x 1 l, then 100 – 150 ml/hr • clinical reassess in 4 – 6 hours • recheck lab in 24 hours
Sodium, Salt • What’s in Normal Saline? • NaCl 154 mmol/l • Na 154 mmol + Cl 154 / liter
Sodium, Salt, Sugar Na+ mmol/l Dextrose in Water 0 ½ Normal Saline 77 Ringer’s Lactate* 130 Normal Saline 154 Hypertonic Saline 513 * Ringer’s Lactate: • Na+ 130 mmol, K+4 mmol, Ca++ 1.5 mmol, Cl− 109 mmol, lactate 28 mmol • electrolyte content is isotonic (273 mOsmol/liter) in relation to the extracellular fluid (approx. 280 mOsmol/liter).
Sodium, Salt • What’s in Normal Saline? • NaCl 0.9% w/v • 0.9 grams solute per 100 grams solvent • 0.9 grams salt per 100 grams water • 9 grams salt per 1,000 grams water • 9 grams salt per 1,000 ml water • Normal Saline is NaCl 9 g / l • Implication for heart failure • Mw(NaCl) = 22.990 + 35.453 = 58.443 g/mol • Na accounts for (23/35) ~ 40% weight of salt • Low Salt Diet = 2 g of sodium = 1 tsp • Low Salt Diet = 2 g / 0.4 = 5 g NaCl • Low Salt Diet = 555 ml of normal saline
Case • 82 year old female in ER • HTN on thiazide • presents with seizure and coma • estimated weight 60 kg • Na = 105 mMol
Sodium Deficit • Calculated sodium deficit *0.6 males x (weight in kg) x (desired sodium - actual sodium)*0.5 for females desired range is 105 mmol/l + 5 mmol/l = 110 mmol/l hypertonic saline has 513 mMol / l of Na
Sodium Deficit • Calculated sodium deficit *0.6 males x (weight in kg) x (desired sodium - actual sodium)*0.5 for females desired range is 105 mmol/l + 5 mmol/l = 110 mmol/l 0.5 x 60 kg = 30 l 30 l x 5 mmol = 150 mmol hypertonic saline has 513 mMol / l of Na 150 / 514 = 300 ml 300 ml over 1 or 2 hours then reassess REASSESS CLINICALLY and BIOCHEMICALLY q 1-2h
Rapid Correction of Hyponatremia • central pontine myelinolysis risk • risk is minimal if increase is 0.5 – 1.0 mmol/h
Case • 30 year old female presents to ER • was hiking in the mountains • drank 10 liters of water per day on the advice of a well meaning friend • delirium with paranoia • Na = 110 mmol/l • ?
Case • 78 year old female on general surgery • Post-op day 3 hemicolectomy for Duke B ca • Overnight developed delirium • Post-op IV order: ‘2/3 – 1/3 @ 125 ml/h’ • Na = 120 mMol
Case • 19 year old man presents to ER • progressive weakness • anorexia and weight loss • nauseated • Na = 128 mMol, K = 6.5 mMol
Case • 82 year old female in clinic • HTN on thiazide • feels well • Na = 125 mMol
Case • 65 year old man on neurosurgery • post-op day 2 brain aneursym clip • Na = 129 mMol
Case • 59 year old female • presents with pneumonia • day 4 feels strange • can eat and drink, likes tea • Na = 120 mMol
Warm Up Case • 81 year old female on stroke unit • doing poorly over last few days • now unconscious • Na = 176 mMol (normal 135-145 mMol)
Clinical Features • Hypernatremia • lethargy • weakness • irritability • twitching • delirium • reduced level of consciousness • coma • seizures ‘neuromuscular irritability’
DDx – HyperNa+ • Not enough water! • no thirst • can’t act on thirst • can’t retain water • except for Normal Saline, not usually a salt issue
Case • 81 year old female on stroke unit • doing poorly over last few days • now unconscious • Na = 176 mMol (normal 135-145 mMol) • estimated weight 60 kg
Diagnosis? • Management? • Solution • Volume • Rate
Solution Na+ mmol/l Dextrose in Water 0 ½ Normal Saline 77 Ringer’s Lactate* 130 Normal Saline 154 Hypertonic Saline 513 * Ringer’s Lactate: • Na+ 130 mmol, K+4 mmol, Ca++ 1.5 mmol, Cl− 109 mmol, lactate 28 mmol • electrolyte content is isotonic (273 mOsmol/liter) in relation to the extracellular fluid (approx. 280 mOsmol/liter).
Rate of Correction Correct no faster than 0.5 – 1 mmol / hr Risk of cerebral edema • determine water deficit • determine duration of correction • rate = deficit / duration (index to hour) • consider ongoing losses • decide on re-assessment
Volume Water Deficit (Na+ measured – 140 mmol/l) 0.6 x kg -------------------------------------- 140 mmol/l use 0.5 for females desired = 140 mMol
Calculate Free Water Deficit Water Deficit (176 mmol / l – 140 mmol/l) 0.5 x 60 x -------------------------------------- 140 mmol/l 7,710 ml 36 mmol / 0.5 – 1.0 mmol/hr = 48 hr 160 ml/hr of ‘free water’ D5W or tube water at 160 ml/hr
Advanced Case • 55 year old female • pituitary resection • post-op dilute polyuria • Na = 165 mMol
DDAVP • IV / sq 1-2 ug q12 h • nasal 10 – 40 ug / day (divide bid / tid) • oral 0.1 – 1.2 mg / day (divide bid / tid) • give hypotonic IV while getting control • usually this is a planned event
Warm Up Case • 78 year old presents with sob • recent gout • indomethacin • creatinine 790 • K = 7.0 mMol
Clinical Features • death