EKG and electrolytes

Question 1

Potassium action

Answer 1

1. K+ and NA+ pump intracellularly / extracellularly
2. Determines conduction velocity
3. Helps to confine pacing activity to the SA node
4. Excess or deficiency can alter myocardial muscle function

Question 2

hyperkalemia EKG changes

Answer 2

(1) Tall, peaked T-waves
(2) Prolonged PRI, loss of P waves, ST segment depression, widening QRS complex
(3) Dysrhythmias – heart block, ventricular fibrillation, cardiac standstill

Question 3

hyperkalemia mechanism

Answer 3

(1) Decreases rate of ventricular depolarization (slows)
(2) Shortens repolarization (accelerates)
(3) Depresses AV conduction

Question 4

hyperkalemia causes

Answer 4

(1) Impaired renal excretion
(2) Excess K+ administration
(3) K+ sparing diuretics (spiralactone), ACE inhibitors, ARB drugs
(4) Extensive skeletal muscle destruction
***(K+ leave cells bc muscle crushed, burned patient expects increase bc it releases K+ since cells destroyed and leak out of blood vessels; burn and crushed injuries leads to this)

overall: either consume too much, kidneys don’t work, or drug is sparing too much K)

Question 5

hyperkalemia management

Answer 5

(1) Stop oral and IV intake of K+
(2) Increase K+ excretion
(3) Force K+ from ECF to ICF (insulin, bicarb, albuterol)
(4) Stabilize cardiac cell membrane

(DICK)

Question 6

hypokalemia EKG changes

Answer 6

(1) Flattened T wave, depresses ST segment, p waves peak, QRS prolonged, U wave
(2) Risk for heart block, ventricular tachycardia, ventricular fibrillation

Question 7

hypokalemia mechanisms

Answer 7

1. impaires myocardial conduction
2. prolongs ventricular replolarization

Question 8

hypokalemia causes

Answer 8

(1) Increased loss of K+ (loop sparing diuretics, increase renal loss, diarrhea)
(2) Increased shift of K+ from ECF to ICF
(3) Dietary K+ deficiency
(4) Renal losses

Question 9

hypokalemia management

Answer 9

Oral or IV K+ replacement
(a) High Alert Medication
(b) NEVER IV push, (Give 10 mEq/hour- infusion pump)
(c) Dilute K+ sufficiently & administer slowly
(d) Monitor for phlebitis

Question 10

magnesium actions

Answer 10

1. Essential for enzyme, protein, lipid, and carbohydrate functions in the body
2. Extracellular level essential for normal cardiac muscle function

Question 11

hypermagnesemia (RARE) EKG changes

Answer 11

like hyperkalemia

(1) Tall, peaked T-waves
(2) Prolonged PRI, loss of P waves, ST segment depression, widening QRS complex
(3) Dysrhythmias – heart block, ventricular fibrillation, cardiac standstill

Question 12

if all electrolytes are abnormally low what do you replace first and why

Answer 12

magnesium since it will overpower K+ and deplete everything. so Mg first, K+ second, and Ca third

Question 13

hypermagnesemia causes

Answer 13

increased intake
excess IV magnesium administration

Question 14

hypomagnesemia EKG changes

Answer 14

(1) Prolonged ST segment, Prolonged QT interval
(2) Torsades de pointes, ventricular fibrillation

Question 15

hypomagnesemia mechanism

Answer 15

(1) Impairs myocardial conduction
(2) Prolongs ventricular repolarization
(3) May lead to coronary artery spasm, hypertension

Question 16

hypomagnesemia causes

Answer 16

(1) Prolonged fasting or starvation
(2) Chronic alcoholism
(3) Fluid loss from GI tract
(4) Diuresis/proton pump inhibitors
(5) Hyperglycemic osmotic diuresis

Question 17

hypomagnesemia management

Answer 17

(1) Treat underlying cause
(2) Magnesium replacement
(a) Mild symptoms – oral replacement and increase dietary intake Mg++
(b) If deficiency severe or if hypocalcemia present, IV Mg++ given

Question 18

calcium actions

Answer 18

1. Mediator for cardiac functions with effect on:
   a) Vascular tone
   b) Myocardial contractility
   c) Cardiac excitability

when replaced Ca also replace vitamin D

Question 19

hypercalcemia EKG changes

Answer 19

(1) Shortened ST segment, shortened QT interval
(2) Ventricular dysrhythmias

Question 20

hypercalcemia causes

Answer 20

(1) Cancer
(2) Hyperparathyroidism
(3) Endocrine disorders
(4) Overdose vitamin A or D

Question 21

hypercalcemia management

Answer 21

(1) Low calcium diet
(2) Increased weight bearing activity
(3) Increased fluid intake
(4) Hydration with isotonic saline infusion
(5) Bisphosphonates
(6) Calcitonin SQ or IM

Question 22

hypocalcemia ekg changes

Answer 22

(1) Prolonged ST segment, Prolonged QT interval
(2) V-tachycardia

Question 23

hypocalcemia mechanisms

Answer 23

(1) Decreases myocardial contractility
(2) Reduces cardiac output
(3) Hypotension
(4) Decreases responsiveness to Digitalis

if too low can causes seizures and dysrhythmias

Question 24

hypocalcemia causes

Answer 24

(1) Decreased production of parathyroid hormone
(2) Multiple blood transfusions
(3) Alkalosis
(4) Increased calcium loss
(5) Low magnesium levels

Question 25

hypocalcemia management

Answer 25

(1) Treat cause
(2) Calcium and Vitamin D supplements
(3) IV Calcium gluconate
(4) Seizure precautions