Electrolytes and ECG changes Flashcards
What are 3 main electrolytes?
Calcium, sodium, potassium
What is calcium balance is controlled by?
PTH (parathyroid hormone) and calcitonin
Influenced by Vitamin D and phosphate
What happens chemically when you have low calcium levels in your body?
Seceretion of PTH which then
>increases calcium absorption from GI tract and
>kidneys which promotes the reabsorption of Ca from the bones, then
>vitamin D is activated in the kidneys,
>promotes the movement of Ca from the bones and intestines into the blood
What is the role of calcium in the body?
Structural strength for bones & teeth
Stability of the nerve membrane, controls the permeability and excitability needed for nerve conduction
Muscle contractions (helps w end of contraction)
Metabolic process and enzyme reactions like BLOOD CLOTTING
What are causes for HYPOcalcemia?
hypoparathyroidism, decrease in PTH
Malabsorption
Renal failure ( vitamin D in kidneys to be absorbed)
- retention of phosphates, loss of calcium
- vitamin D is not activated
What are some results on HYPOcalcemia?
increases permeability and excitability of nerve membranes (muscle twitching, carpopedal spasms, hyperventilation syndrome)
severe–> laryngospasms and airway obstruction
heart: contractions are weak, conduction is delayed, arrhythmias develop, cardiac output drops
What is the difference between heart and skeletal muscles?
Skeletal- have an increased irritability of the nerves that control muscle fibres, calcium is stored IN the muscle!
Heart- NO nerves, contraction is directly affected by calcium levels, only available through calcium channels
What are causes of HYPERcalcemia?
Cancer
HYPERthyroidism
Immobility (disease stress on bones and demineralization
Increased intake of vitamin D
overdose of milk and antacids
What does HYPERcalcimenia result in?
muscle weakness
loss of tone
interefere with ADH, less absorption: polyuria (excessive urine)
severe: blood volume drops, renal function impaired, wastes accumulate (acidic) , cardiac arrest
heart: contractions increase strength and duration with dysrhythmias developing
bone: excess PTH, calcium intake, bone density and strength are affected
What is sodium balance controlled by?
by the kidney via aldosterone
What is the function of sodium?
- nerve impulse conduction
- muscle contraction
- extracellular fluid volume (affects osmotic pressure)
- force with which a solvent (fluid) passes through a membrane separating solutions of different concentrations
What are some causes of hyponatremia?
- excessive sweating, vomiting, diarrhea
- diuretic medications used with low fat diets
- hormonal imbalances
- chronic renal failure
- excessive water intake!
What are some results of hypnatremia?
- imparied nerve conduction, SLOWER
- fluid imbalances (fatigue, muscle cramps, abdo discomfort, cramps with nausea and vomitting)
- decreased osmotic pressure outside cells: fluid shift the cells: hypovolemic and drop in BP
- brain swelling, CNS effects, headaches, confusion, seizures
What are causes of HYPERnatremia?
- ingestion of large amounts of sodium
- disproportionate water intake
- insufficient antidiuretic hormone
- loss of thirst mechanism
- loss of thirst
- watery diarrhea
What are results of hypernaatremia?
weakness, agitation, increased thirst with dry rough mucous membranes
- decreased urinary output (ADH secretions)
- increased urinary output (if the cause is ADH insuffiency
What controls potassium balance?
Insulin promotes the movement of K in the cells
excreted in the urine under the influence of aldosterone
Acidosis, shifts K ___ of the cells. Explain this more.
OUT!
Alkalosis, shifts K __ the cells!
INTO!
What are the roles of potassium in the body?
regulates intracellular fluid volume
metabolic process in the body
nerve conduction
contraction of all muscle types
membrane potential
cardiac muscle contraction= ECG changes=cardiac arrect!!!
What are causes of HYPOkalemia?
Excessive loss of K from diarrhea, diuretic drugs
Excessive aldosterone or glucocorticoids, sodium retention, potassium execeretion
Decreased dietary intake (alcoholism, ED’s, starvation )
What is results of hypokalemia?
-cardiac dysrhythmias, prolonged repolarization
-neuromuscular function interference
-muscle are less responsive stimulus- fatigue, muscle weakness
-paraesthesia, pins and needles
- decreased GI motility (anorexia and nausea)
- renal malfunction, polyuria
- weak respiratory muscles, shallow resps.
Causes of HYPOkalemia?
renal failure
deficit of aldosterone
K sparing dieuretics
K leakage out of cells w tissue damage, CRUSH SYNDROME
Acidosis, displaces potassium
Potassium changes on ECG shows…..
P waves wide and flat
longer PRI
Wide FLAT QRS
T wave is HIGH and WIDE
Hyperkalemia treatment is…. (ACP ONLY)
Ventolin high dose (1600mcg/dose MDI or 10mg neb)
Calcium gluconate (1g IV)
What is the most dangerous of ALL electrolyte changes??
HYPERKALEMIA
- can kill in seconds
- prevents response to drugs in resuscitation!
What does hyperkalemia cause in ECG’s?
QRS complex changes
ANY and ALL arrhythmias
What are the main changes in hyperkalemia?
Tall and peaked T waves
P waves missing or decreased amplitutde
ST segment changes, stimulating an injury pattern
cardiac arrythmisas (any wide rhythm)
what is the first difference in a pt’s ECG that you would see developing hyperkalemia?
T WAVE ABNORMALITIES
What are the waves produced during severe hyperkalemia called?
SINE WAVES!!!
What are ECG changes on a pt w HYPOkalemia?
There are nonspecific changes:
Mild ST segment depression
Mild decrease amplitude of T wave
MInimal prolongation of QRS interval
Prominent U wave (most common)
Small wave that occurs after T wave
What can severe hypercalcemia mimic?
an acute MI!
(cardiac dysrhythmias are rare though)
