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
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CVP 2
I/0 balance = -600
What could be happening?
What labs would you send?
Case 1
• Differential diagnosis:
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Post resuscitation diuresis
Polyuric ATN
Hyperglycemia/post-mannitol
Central Diabetes Insipidus
Cerebral salt wasting
• Labs to send:
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UA with spec grav
Urine osmolality, Urine sodium
Serum osmolality, Serum sodium
Basic metabolic panel
Case 1
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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 34ml/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
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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….
thirst
vasopressin
Plasma osmolality
Salt intake
vasopressin
thirst
Renin-angiotensin
Blood pressure/effective ECF
Atrial naturietic factor
Symphathetic
nervous system
Salt intake
Hyponatremia
Hyponatremia: Clinical signs and
symptoms
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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)
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SIADH
Glucocorticoid deficiency
Hypothryoidism
Psychogenic polydipsia
Drugs: desmopressin, psychoactive agents, chemotx
Hyponatremia: Causes
• Hypervolemia (Una<20)
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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, postoperative, 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
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Nausea/vomiting
Restless, irritable, or lethargic
Anorexia
Stupor/coma
Subarachnoid hemorrhage--Why?
Hypernatremia: Causes
• Free water loss
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Diuretics (loop)
Post obstructive diuresis
Acute and chronic renal disease
Sweating, fistula, burns, diarrhea, vomiting
Diabetes insipidus (central, nephrogenic)
• Sodium gain
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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 (280290mOsm/L)
Urine osm
>500mOsm/L
increased
decreased
variable
Urine to serum >1
osm ratio
>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?
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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
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 shift
Alkalosis, 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 homeostasis
Hormone
Calcium
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
Decreased
bone
resorption/
decreased
kidney
reabsorption
No effect
Calcitonin Decrease
Phosphate
Hypocalcemia
• Symptoms appear when iCa<0.7
• Symptoms include:
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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:
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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
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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!