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