Serum Electrolyte disorders Flashcards Preview

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Flashcards in Serum Electrolyte disorders Deck (34):
1

Potassium Normal Range

  • 3.5-5.5 mEq/L
  • 98% intracellular
    • muscle cells
  • Kidney imp for regulation
  • Acidosis draws K out of cell / Alkalosis drives it into cell

2

K+ effect on cell membrane

  • Inc K+
    • sustained depolarization => weak animal
    • inc excitability
    • dec membrane potential
  • Dec K+
    • Sustained hyperpolarization => weak animal
    • dec excitability
    • inc membrane potential

3

Inc K+ effect on heart

Arrhythmias

  • Increasing K+
    • peaking of T wave =>
    • Atrial standstill, widened QRS and T
    • Depression of ST
    • Biphase tracing
    • Ventricular tracing
    • Ventricular fibrillation
    • Terminal
  • Arrhythmias
    • sinus bradycardia
    • sinus arrest
    • First deg AV block
    • Nodal rhythm
    • idioventricular rhythm
    • ventricular tachycardia
    • ventricular fibrillation
    • ventricular arrest

4

Dec K+ effect on heart

Arrhythmias that can occur

  • Dec K+
    • Low T wave
    • Atrioventricular conduction defect
    • sagging ST
    • Prominant U wave....WTF is this?
  • Arrhythmias
    • Ventricular premature beats
    • Atrial tachycardia
    • Nodal tachycardia
    • Ventricular tachycardia
    • Ventricular fibrillation

5

Clinical signs Hypokalemia

  • Serum K+ < 2.5 mEq/L
  • Muscle weakness is primary sign
  • Other signs
    • lethargy
    • confusion
    • PU/PD
    • carb intolerance = low K causes inc in blood glucose, less insulin secretion...
    • ileus
  • EKG changes unpredictable

6

General causes of hypokalemia

  1. Movement into cells
    • insulin
  2. GI loss
    • vx/d
  3. Renal loss
    • cats

7

Vomiting without diarrhea think....

  1. obstruction => always look under the tongue of every vomiting dog and cat for string of linear foreign body
  2. pancreatitis

8

Hypokalemia TX with K

  • Mild (3.0-3.5 mEq/L)
    • 20 mEq/L
  • Moderate (2.5-3.0)
    • 30-40 mEq/L
  • Severe (< 2.5)
    • 60 mEq/L

9

K+ Rate of infusion

  • 0.5 mEq/kg of body weight per hour
  • can go up to 1.5 mEq/kg with EKG monitoring

*rate is more important than total amount

10

Hyperkalemia values

  • Mild (5-6.5)
  • Moderate (6.5-8.0)
  • Severe ( > 8)

11

Signs of hyperkalemia

  • Muscle
    • weakness due to depolarization
  • Cardiac
    • excitation and conduction abnormalities (when > 7-8 mEq/L)

12

Sequence of hyperkalemic EKG changes

  1. High T wave (should only be 1/4 the R wave)
  2. Prolonged PR interval, high T wave, depressed ST segment
  3. Auricular standstill, Intraventricular block
  4. Ventricular fibrillation

*no P waves = atrial standstill

*oliguric/anuric animals, Addisonian criseses, K overdose, cats with urethral obstruction

13

Main mechanisms hyperkalemia

  1. Too much intake
  2. impaired excretion
    • ARF
    • Addison's
  3. Shifting
    • metabolic acidosis
  4. Drugs
    • aldosterone inhibitors
      • spironolactone
    • ace inhibitors (angiotensin converting enzyme inhibitor)

14

Aldosterone

  • acts on distal tubules of kidney
    • Na reabsorption
    • K secretion

*No aldosterone: K goes up, Na goes down

15

Other causes of Hyperkalemia

  • Cell death
  • Acidemia
  • Lack of insulin
  • Hypertonic plasma
  • Medications
    • B-blockers
    • digoxin
    • penicillin
    • KCl IV fluid
  • Severe exercise (rhabdomyelysis)
  • stored blood (old red blood cell transfusion)

16

False Hyperkalemia

  • Cushing's dog with high platelet count
    • normally take blood and put in clot tube (red tube, standard for chems)
      • serum would be sent to lab, this serum would have lots of K released during the clotting process
    • THEN collect blood into a green tube (heparinized)
      • This sample is plasma and will have true potassium measurement

17

Treatment for hyperkalmemia

  • Ca Gluconate
    • won't lower serum potassium but will save heart
    • works within a few minutes
  • NaHCO3
    • lowers serum K (pushes K into cell)
    • > 30 minutes
    • not really used, needs high dose and side effects of bicarb
  • Insulin - dextrose
    • lowers serum K (pushes K into cell)
  •  Diuresis - furosemide
  • Hemodialysis
  • Terbutaline, albuterol, aminophylline
    • beta agonist => pushes K into cell
    • minutes

18

Measurement of Na reflects

  • Extracellular water content

19

Hyponatermia

Causes

  • Big problems when Na+ < 120
    • Brain swelling - demyelination

Causes

  • Water gain-more common
  • Na loss - Addison's

20

Hyponatremia signs

  • weakness
  • apathy
  • dementia
  • stupor/coma
  • absence of thirst
  • decreased skin elasticity
  • hypotension
  • hypothermia
  • shock
  • seizures
  • myoclonus

21

Hyponatremia Classification

  1. Euosmolar
  2. Hyperosmolar
  3. Hypoosmolar

22

2 main causes of acute hyponatremia

  • Intake of large quantities of hypotonic fluid (oral/IV)
  • Impaired H2O secretion
    • inappropriate ADH release

23

D5W

Dextrose 5% in water

Not used to correct hypovolemia

hypernatremia

Na intolerant patients

24

TX Acute hypo Na

TX Chronic hypo Na

TX Acute hypo Na (occured w/in 24-36 hours)

  • Remove causative factors
  • Can correct rapidly over 24 hours
  • Replace sodium at rate of at least 1 mEq/L/hr

TX Chronic hypo Na (occured over several days)

  • Correct slowly

25

Hypernatremia

  • Problems around 170 mEq/L => hypertonic encephalopathy

26

Hypernatremia main causes

  • Na gain - uncommon
  • water loss - common

27

Effects of Hyperosmolality on Neurons

  • Hypertonicity
  • Intracellular water => ECF
  • Neuron dehydrates
  • Retraction and tearing of meningeal vessels
  • CNS hemorrhage
  • Neuron dysfunction
  • patient can die

28

Idiogenic osmoles

  • In hypernatremia brain creates these to keep fluid in the brain
  • If patient corrected too quickly the brain will swell

29

Hyper Na signs

  • Fever
  • Nausea
  • Vomiting
  • Seizures
  • Coma
  • Neuro signs
  • Hypotension
  • Tachycardia
  • Oliguria unless DI

30

Types of hyper Na

  1. Hypovolemic: renal, GI
  2. Hypervolemic: hypertonic saline TX
  3. Euvolemic: DI

31

TX Hyper Na

  • Stop water diuresis by giving ADH to DI patient
  • Stop any hypertonic fluid infusion
  • Give 0.45% NaCl or D-5-W IV
  • Acute hyper Na can be treated over several hours, restored w/in 24 hours
  • Chronic hyper Na correctly slowly over 48-72 hours

32

Alkolosis usually goes along with ______

  • Hypokalemia
    • causes insulin resistance
  • LRS BAD
    • lactate converted to bicarb in liver
  • If rehydrating a sick patient but Na is rising too fast
    • give Furosemide

33

Emergency medicine priorities

  1. Hypovolemia
    • once BP is 60 it's permissible, can give furosemide
  2. Acid-base
  3. Electrolytes

34

Central Pontine Myelinosis

  • Iatrogenic brain demyelination from too rapid correction hypo Na
  • Maximal rate of correction 
    • Don't exceet 0.5 mEq/L/hr
    • Max 8-12 mEq/L per 24 hours