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Electrolyte management in the PICU
2012
Goals
• To discuss the pathophysiology of electrolyte disturbances
• To review the acute management of electrolyte disturbances
• To discuss 2 cases with audience participation
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.
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?
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
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
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
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.
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)
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
The body keeps your Posm between 280-290 mOsm/L….
Plasma osmolality
vasopressin thirst
Salt intake
Blood pressure/effective ECF
vasopressin
Symphathetic nervous system
Atrial naturietic factor
Renin-angiotensinthirst
Salt intake
Hyponatremia
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!
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
Hyponatremia: Causes
• Hypervolemia (Una<20)• Acute or chronic renal failure Una>20• Congestive heart failure• Cirrhosis/hepatic failure• Nephrotic syndrome
• Hyperosmolar• Hyperglycemia, mannitol, glycine
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!
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)
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
Hypernatremia
Hypernatremia: Clinical signs and symptoms
• Nausea/vomiting
• Restless, irritable, or lethargic
• Anorexia
• Stupor/coma
• Subarachnoid hemorrhage--Why?
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
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
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
SIADH CSW DI central Post resus
diuresis
Body water Increased decreased decreased Normal or increased
Sodium low low high normal
Serum osm <280mOsm/L decreased >300mOsm/L Normal (280-290mOsm/L)
Urine osm >500mOsm/L increased decreased variable
Urine to serum osm ratio
>1 >1 <1.5 variable
Urine output low high high high
Urine sodium increased increased decreased variable
Case 2
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:
Case 2
• What is this rhythm?
In case you were wondering, this is BAD!!!!
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
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
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
Hypokalemia
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)
EKG in hypokalemia
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 shiftAlkalosis, beta agonists, caffeine, insulin,
thryrotoxicosis, hypokalemic periodic paralysis
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
Hyperkalemia
Hyperkalemia
• Definition: K>6 mEq/L
• Symptoms• EKG changes: peaked T waves, prolonged PR
interval, widened QRS, V-fib• Muscle weakness/paresthesias
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
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
Ca, Mg, Phos
Calcium homeostasisHormone Calcium Phosphate
PTH Increase Kidney reabsoption of Ca
decreased Decreased absorption in kidney
Vitamin D Increase Increased absorption in kidney and intestine
increased Increased absorption in kidney and intestine
Calcitonin Decrease Decreased bone resorption/ decreased kidney reabsorption
No effect
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
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
Hypocalcemia: Causes
• Calcium chelation/precipitation• Tumor lysis, rhabdomyolysis, citrate, foscarnet
• Multifactorial• Sepsis, pancreatitis, burns
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)
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)
Hypomagnesemia
• Treatment• Magnesium sulfate 25-50 mg/kg• Replace potassium and calcium• Oral supplementation
Hypophosphatemia
• Symptoms• Muscle weakness, paralysis• Respiratory depression• Leukocyte and platelet dysfunction• Hemolysis
• Causes• Decreased intake or malabsorption• Decreased renal reabsorption (hyperparathyroidism,
fanconi’s, vitamin D deficiency, medications)• Transcellular shift (catecholamines, theophylline,
respiratory alkalosis)
Hypophosphatemia: Treatment
• Determine underlying cause (many times it is multifactorial)
• Replace using:• NaPhos• Kphos 0.08-0.32 mmol/kg over 4-6 hours
REVIEW QUESTIONS
What is the most effective way to lower serum K?
Insulin and glucose
How do you treat seizures due to hyponatremia?
3% NS 4ml/kg
Why does low magnesium often cause hypocalcemia?
Low magnesium inhibits PTH release
What electrolyte abnormality may lead to failed extubation
attempt?
hypophosphatemia
Thank you!