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Emergency Medicine
May 25, 2010
Electrolyte DisturbancesAndrew Petrosoniak
PGY2 Emergency MedicineUniversity of Toronto
Canada
Emergency Medicine
May 25, 2010
1. Overview of hyperkalemia & hyponatremia2. Important diagnostic tests3. Management 4. This presentation also includes hypokalemia &
hypernatremia – but for youre own reading!
Objectives
Emergency Medicine
May 25, 2010
Case74 y female with shortness of breath and weaknessBP 135/58 HR 105bpm SpO2 96% RR 24Additional history, she just started ACE inhibitor last
week for hypertension
Emergency Medicine
May 25, 2010
Hyperkalemia: Overview
• 90% of potassium is intracellular• Ratio of extracellular to intracellular potassium (K)
essential for cell membrane potential • Most K is eliminated via kidneys (95%) • K excretion occurs at distal nephron (collecting
duct)
Emergency Medicine
May 25, 2010
Emergency Medicine
May 25, 2010
Hyperkalemia: Causes
1. Lab/Human error (e.g. hemolysis)2. Renal Failure +/- acidosis3. Cell death (burns, tumor lysis syndrome) 4. Drugs/Toxins/Medications
A. Potassium supplementsB. Non-selective beta-blockers (propanolol)C. SuccinylcholineD. DigoxinE. K-sparing diureticF. ACE inhibitorsG. Pentamidine & Trimethroprim
Emergency Medicine
May 25, 2010
Pseudohyperkalemia
• Related to collection and storage of specimen• Difficulty in collecting sample • Patient clenched fist when sample was taken• Sample was shaken or squirted through needle into
collection tube• Cooling• Deterioration of specimen due to length of storage• Thrombocytosis• Severe leucocytosis (which can also produce
pseudohypokalaemia)Smellie BMJ 2007; 334: 693
Emergency Medicine
May 25, 2010
HYPERKALEMIA = ECG
ECG may not correlate with potassium levels and so may NOT accurately predict likelihood for cardiac arrest
Emergency Medicine
May 25, 2010
Hyperkalemia: ECG
1. Peaked T waves2. Widening QRS 3. Loss of P wave 4. Sine wave 5. Ventricular fibrillation/Asystole
Emergency Medicine
May 25, 2010
Emergency Medicine
May 25, 2010
Emergency Medicine
May 25, 2010
Emergency Medicine
Potassium quintiles by presence of strict criteria for electrocardiogram (ECG) changes.
Montague B T et al. CJASN 2008;3:324-330
©2008 by American Society of Nephrology
Emergency Medicine
May 25, 2010
Hyperkalemia: Management
1. Membrane antagonism2. Intracellular shift of potassium3. Elimination of K from body
Emergency Medicine
May 25, 2010
When does the patient need calcium?
• Decision to treat emergently varies among clinicians
• Consider some will ONLY treat if ECG changes
SAMPLE GUIDELINES1. Plasma K > 6.52. EKG manifestations regardless of plasma level* Consider acuity of rise
Weisberg Crit Care Med 2008
Emergency Medicine
Membrane antagonism: calcium
Patient in cardiac arrest, sine wave or central venous access
• IV Calcium Chloride (10%) 5ml over 2min**irritates veins, risk of extravasation
All other situations• IV Calcium gluconate (10% - 1amp) 10ml
over 2-10min
Emergency Medicine
Intracellular potassium shift
1. IV Insulin R 10U and 2 amps D50 (50g) – Effect: 10-20min; Decr K level by 0.6-1.0mEq/L
2. Albuterol/Salbutamol 20mg in 4ml NS nebulized – Effect may last 1-2hrs: Decr K level by
0.6mEq/L3. IV Sodium Bicarbonate (NaHCO3) 1-2 amps (50-
100mEq/L) – Only if acidosis
Emergency Medicine
Elimination of K from body
1. Kayexalate 20-40mg PO/PR – Onset 2-6hrs; studies show mild effects– Risk of colonic necrosis
2. Furosemide 40-80mg IV 3. Dialysis
Emergency Medicine
May 25, 2010
Case74 y female with shortness of breath and weaknessBP 135/58 HR 105bpm SpO2 96% RR 24Additional history, she just started ACE inhibitor last
week for hypertension
Emergency Medicine
May 25, 2010
Case74 y female with shortness of breath and weaknessBP 135/58 HR 105bpm SpO2 96% RR 24Additional history, she just started ACE inhibitor last
week for hypertension Management• Calcium• Insulin & D50• Ventolin• Kayexalate• Consider HCO3 if acidosis• Lab calls and K=9.5
Emergency Medicine
May 25, 2010
• Causes of hyperkalemia• Make sure it is TRUE hyperkalemia• ECG manifestations• If >6.5 or any ECG changes give
calcium
Recap: Hyperkalemia
Emergency Medicine
Sodium
• Primarily extracellular cation • Closely related to total body water • Sodium moves into cells• Na/K ATPase transports Na back out of cells
Emergency Medicine
May 25, 2010
Sodium Balance
• Renin = released with low intravascular volume– Triggers sodium reabsorption & potassium
excretion in distal nephron (via aldosterone)• ADH = released with high serum osmolality
– Enhances renal water reabsorption – Other triggers: angiotensin, catecholamines,
opiates, caffeine, stress, hypoglycemia, hypoxia
Emergency Medicine
May 25, 2010
Case
• 85 y male found with decreased level of consciousness at home
• History of dementia but still functions at home• Found in his own urine, appears to have bit his
tongue• BP 105/58, HR 74 RR 16 SpO2 94%• GCS 12 (E3V3M6)• Lab calls you because his serum Na = 103
Emergency Medicine
May 25, 2010
Hyponatremia
• Serum sodium <135mmol/L• Establish whether true hyponatremia (check
glucose)– Na drops 3 mEq for every 10mmol increase of glucose
Emergency Medicine
Hyponatremia
Two KEY questions • Does the patient have any neurologic symptoms
possibly related to hyponatremia?• What is the patient’s volume status?
3 Other considerations1. Is there a sample error? E.g. IV near D5W infusion
2. Is it pseudohyponatremia? Hyperlipidemia/hyperproteinemia
3. Is there another osmole? E.g. Mannitol or Hyperglycemia
Emergency Medicine
• Hypovolemic: Loss of sodium more than water• Euvolemic: Most commonly SIADH =
inappropriately concentrated urine • Hypervolemic: Both sodium & water retained but
water >> Na
Emergency Medicine
Volume StatusVolume Status
HyponatremiaHyponatremia
HYPOVOLEMIC•Renal losses•GI losses•Excess sweating•Addison’s disease•3rd spacing (burns)
EUVOLEMIC•SIADH•Psychogenic polydipsia
HYPERVOLEMIC•CHF•Hepatic cirrhosis•Nephrotic syndrome
Emergency Medicine
SIADH: causes
• CNS disease (tumor, infection, trauma)• Pulmonary disease (pneumonia, TB, lung abscess)• Drugs (diuretics, chemotherapy)
Emergency Medicine
Hyponatremia: Clinical features
• Lethargy, confusion, agitation• Weakness• Focal neuro deficits• Seizures• Altered level of consciousness
Emergency Medicine
KEY POINTS• Always consider sodium abnormality in patient
with altered level of consciousness
• Acute hyponatremia: usually symptoms if <120mEq/L
• Patients with chronic hyponatremia may tolerate lower levels without symptoms
Emergency Medicine
May 25, 2010
Investigations
• CBC• Electrolytes• Serum osmolality • Uric acid• Consider TSH & cortisol• Urine: urinalysis, urine electrolytes, urine
osmolality, urine creatinine
Emergency Medicine
May 25, 2010
Emergency Medicine
May 25, 2010
Hyponatremia: work-up
• Serum osmolality: Normal or elevated suggests presence of additional osmole (e.g. glucose, hyperlipidemia) – If hypotonic (low serum osmolality) then assess patient’s volume
status
• Urine osmolality & urine electrolytes
Emergency Medicine
May 25, 2010
When does the patient require emergent treatment?• Neurologic impairment • Currently seizing or post-ictal• Altered level of consciousness or comatose
Emergency Medicine
May 25, 2010
Immediate treatment is only required if the patient has neurological symptoms
Emergency Medicine
May 25, 2010
Hyponatremia: Emergency therapy
Goals of treatment: Rule of 6s• Increase serum Na by 6mEq per day• Increase serum Na by 6mEq in 6hrs if neurologic
symptoms
www.emcrit.orgSterns et al. 2010 Am J Kidney Dis 56:774
Emergency Medicine
May 25, 2010
Hyponatremia: Emergency therapy
• IV 100cc of 3% saline over 20 minutes• If patient does not improve, then repeat 10
minutes later• Each 100cc will raise sodium by ~2mmol/L • Then STOP! Fluid restriction and admit to hospital• If persistent neurologic deficits, consider CT head
www.emcrit.orgSterns et al. 2010 Am J Kidney Dis 56:774
Emergency Medicine
May 25, 2010
Hyponatremia: Over correction
• Rapidly overcorrection of serum sodium can cause osmotic demyelination syndrome
• Risk if >10mEq/L correction in 24hr period• Risk factors include:
– Chronic hyponatremia– Serum Na <105mEq/L– Alcoholism– Malnutrition, liver disease
• If concern about overcorrection then DDAVP 1-2mcg IV and consult nephrology
Emergency Medicine
May 25, 2010
• Hypovolemic hyponatremia: volume deficits can be corrected with IV NS 0.9%
• Euvolemic hyponatremia: free water restriction (500cc-1L/day)
• Hypervolemic hyponatremia: fluid restriction, cautiously use diuretics (may increase Na urine excretion)
Emergency Medicine
May 25, 2010
Case
• 85 y male found with decreased level of consciousness at home
• Found in his own urine, appears to have bit his tongue• BP 105/58, HR 74 RR 16 SpO2 94%• GCS 12 (E3V3M6)• Lab calls you because his serum Na = 103
Management• Neurologic impairment & probable seizure = 3%
saline, start with 100cc, may require 2nd dose• Monitor electrolytes every 4hrs, and give no additional
fluid
Emergency Medicine
May 25, 2010
Recap: Hyponatremia
• Only correct serum Na levels if neurological symptoms
• IV 100cc 3% saline (consider repeat)• Rule of 6s • Risk of osmotic demyelination syndrome• Overcorrection: DDAVP & nephrology
Emergency Medicine
Hypokalemia
• Assess muscle weakness/need for increased respiratory muscle use (e.g. metabolic acidosis)
• Is this an emergency? (ECG changes) • Usually ABG also helpful
Emergency Medicine
Causes• Drugs (often thiazides, furosemide)• GI losses (vomiting/diarrhea)• Hormones• Bicarb abnormalities• Renal tubular defects• Magnesium deficiency
Emergency Medicine
• Decreased intake• Increased loss
– Renal (CHF, nephrotic syndrome, dehydration)
– Renal tubular defects (RTA) – GI losses (Vomiting, laxatives, diarrhea) – Drugs (Diuretics, Ampho B, mannitol,
Aminoglycosides• Transcellular shifts
– Alkalosis (vomiting, diuretics) – Insulin– Beta agonists
Causes
Emergency Medicine
Clinical Manifestations• Cardiovascular: Arrhythmias, ECG changes,
Digitoxicity• Skeletal muscle: weakness, cramps, tetany,
paralysis (K<2.0) • Smooth muscle: constipation, urinary retention• Metabolic alkalosis
Emergency Medicine
May 25, 2010
HYPOKALEMIA = ECG
Emergency Medicine
Hypokalemia: ECG changes
• Usually occurs when K <2.7mmol/L• PR prolongation• T wave flattening or inversion• ST depression• U waves• Apparent long QT interval (T & U waves fuse
together)
http://lifeinthefastlane.com/ecg-library/basics/hypokalaemia/
Emergency Medicine
http://lifeinthefastlane.com/ecg-library/basics/hypokalaemia/
Emergency Medicine
Emergency Medicine
ManagementPO replacement is preferred unless IV is indicated
Indications for IV therapy • Dysrhythmias• Prominent symptoms• Unable to tolerate PO• Likely if K<2.5mEq/L
IV dose 10- 20mEq/hr (upto 40mEq/hr if central line)
Emergency Medicine
ManagementGoal of therapy• K = 4.0 – 4.5• Probably reasonable to increase serum Mg
levels to >1.0
Emergency Medicine
Management: Formulations• Formulation depends on etiology & other
electrolyte levels• 1mEq drop in serum level = 100-200mEq total
body store• KCl 20-40mEq PO 2-4 times/day (available in liquid,
powder, pill) • KCl 20-40mEq IV in NS/RL• Other formulations include K-phos, K-bicarb, K-
citrate
Emergency Medicine
Recap hypokalemia
• Causes: think diuretics, diarrhea • Get an ECG• Clinically not an issue until <2.0 then think
paralysis/weakness • Always check Mg, and likely replace it
Emergency Medicine
May 25, 2010
Hypernatremia: Overview
• Serum Na >145mEq/L • Hypernatremia is a state of hyperosmolality • In general, causes are:
– Thirst or water access related– Renal concentrating problems (kidney or hormone related)– Free water losses
• In normal conditions: – water intake = losses– Salt intake = losses
• One or both of these are disrupted in hypernatremia
Emergency Medicine
May 25, 2010
Hypernatremia: Overview
Hypernatremia is a “water problem”
Each litre of free water loss causes 3-5mEq rise in sodium
Emergency Medicine
May 25, 2010
Hypernatremia: Etiologies
• Reduced water intake– Inability to obtain water– Disorders of thirst perception
• Increased water loss– GI losses: vomiting, diarrhea, third spacing– Renal losses: diabetes insipidus, renal tubular defects– Dermal losses: sweating, severe burns
• Increased sodium – Exogenous sodium: salt tablets, hypertonic saline, – Increased reabsorption: Cushing’s disease, Exogenous
corticosteroids, congenital adrenal hyperplasia
Emergency Medicine
May 25, 2010
Hypernatremia
• Two questions1. What is the patient’s volume status?2. Is the problem acute or chronic?
Emergency Medicine
May 25, 2010
Hypernatremia
Hypovolemia Euvolemia Hypervolemia
• GI losses• Diuretics• Acute & chronic kidney disease• Hyperosmolar non-ketotic coma• Dermal losses
• Diabetes insipidus • Fever• Mechanical ventilation
• Iatrogenic• Hyperaldosteronism
eMedicine. Hypernatremia 2010Reynolds et al. BMJ 2006;332(7543):702-705
Emergency Medicine
May 25, 2010
Hypernatremia: Diabetes insipdus
• Loss of large amounts of dilute urine• Lack of concentrating ability in distal nephron• Two main classifications
– Central: Lack of ADH secretion – Nephrogenic: Kidneys no longer respond to ADH
• sdf
Emergency Medicine
May 25, 2010
Hypernatremia: Investigations
• CBC• Serum electrolytes• Serum glucose• BUN, Creatinine• Urine electrolytes• Urine osmolality• Plasma osmolality• Measure urine output
Emergency Medicine
May 25, 2010
Hypernatremia: Diagnosis
• Establish volume status of the patient• Hypovolemia
– Urine Na <10mEq/L: extrarenal fluid loss– Urine Na >20mEq/L: renal losses (diuretics, osmotic
diuresis)
• Euvolemia– High urine osmolality (>600-700 mOsm/kg): increased
insensible losses– Low urine osmolality (<300 mOsm/kg): diabetes insipidus
Emergency Medicine
May 25, 2010
Hypernatremia: Clinical features
• Dehydration• Anorexia, nausea, vomiting, fatigue• Lethargy, confusion, coma• Hyperreflexia, spasticity, tremor, ataxia• Focal findings: upgoing toes, hemiparesis
Emergency Medicine
May 25, 2010
Hypernatremia: Clinical features
Serum Osmolality• > 350 = excessive thirst• > 375 = weakness & lethargy• > 400 = ataxia, tremor• > 420 = focal neurological deficits, hyperreflexia • > 430 = coma & seizures
Emergency Medicine
May 25, 2010
Management• Rate of sodium correction depends on how acutely
hypernatremia developed & symptom severity • Acute: <48hrs • Chronic: >48hrs – requires slower correction
because of risks of cerebral edema
Emergency Medicine
May 25, 2010
ManagementAcute hypernatremia can be corrected at 1mmol/L per hour
Chronic hypernatremia can be corrected at 0.5mmol/L per hour and no more than 10mmol/L per 24hrs
• replace 50% of free water deficit in 12-24hrs and remaining deficit over next 24hrs • routinely check serum & urine electrolytes • perform serial neurological examinations
Emergency Medicine
May 25, 2010
Management• Hypovolemic: Restore volume deficits with IV NS 0.9%
until hemodynamically stable then replace free water deficits
• Euvolemic: Treat with hypotonic fluids with steps below
• Calculate Total body water– Weight x % body water
• Calculate change in serum Na after 1L of fluid (e.g. D5W or 0.45NS)
• Change in serum Na = (infusate Na – serum Na) / (TBW + 1)
• Amount of solution required = Serum sodium goal decrease / change in serum Na after 1L of fluid
Emergency Medicine
May 25, 2010
ManagementCase Example75 year male, obtunded, dry mucous membranes, fever,
otherwise normal vital signs. Serum Na = 165 mmol/L; weight = 70kg
Total body water = 70kg x 0.5% = 35L Change in serum Na (using 1L of D5W) = (0 – 165) / (35 + 1) = -
4.6mmolGoal over 24hrs, decrease by 10mmol/L10/4.6 = 2.17 L required plus 1L estimation of obligatory water
loss = 3.17LThus over 24hrs, he’ll require D5W at 132cc/hr
Lukitsch I. eMedicine. Hypernatremia 2010
Emergency Medicine
May 25, 2010
Hypernatremia: complications
• Coma & seizures• Cerebral edema (if rapid correction)• Intracerebral hemorrhage especially in neonates
Emergency Medicine
May 25, 2010
References• eMedicine• Rosen’s Emergency Medicine 7th
edition• Medscape• Listed literature sources• Emcrit.org• EMRap