8- Electrolyte imbalace Flashcards
Electrolytes and EKG changes
Between K+ and NA+ which cation has effect on prolong QT?
K+
Between K+ and NA+ which cation has effect on wide QRS complex, aberrant conduction, bundle branch defects?
Hypo/ hypernatermia (NA)
Causes of Hyperkalemia?
Contributing factors
-Renal Impairment
-Adrenal Insufficiency
-Drugs
-Acidosis
-Hemolysis
-Hyperosmolarity
-Excessive intake
-Deficiency of aldosterone will result in potassium retention, through its inability to excrete potassium in the urine, Drugs- ACEs, ARBS, potassium sparing diuretics, nsaids (prostacyclin inhibition)
-Hyperosmolarity- gradient pulls water out of cells, intracellular potassium increases
What are the signs and symptoms of Hyperkalemia?
-Cardiac conducting system abnormalities including
dysrhythmias, conduction abnormalities, and cardiac
arrest
-If plasma [K+] is <6.0 mEq/L, cardiac effects are
generally negligible
-As the concentration increases, may see tall,
peaked T waves
-With further increases, the PR interval becomes
prolonged, followed by a decrease in the
amplitude of the P wave
-Finally, the QRS complex widens into a pattern
resembling a sine wave and eventually culminates
in VF arrest and asystole
-At plasma [K+] 7.0 mEq/L, may have ascending
paralysis that progresses to flaccid paralysis, inability
to phonate, and respiratory arrest
-High levels of potassium cause abnormal heart and
skeletal muscle function by lowering cell-resting
action potential and preventing repolarization,
leading to muscle paralysis.
Hyperkalemia: EKG
Hyperkalemia: Treatment?
Reverse membrane effects
-Ca gluconate (peripheral IV)
-Ca chloride (central line)
Transfer extracellular [K+] into cells
-Bicarbonate (NaHCO3)
-Insulin
-ß2 agonists
Remove potassium from body
-Kayexalate
-Diuretics (proximal or loop)
-Dialysis
NOTES:
Calcium antagonizes the cardiac effects of hyperkalemia. It raises the cell depolarization threshold and reduces myocardial irritability. Calcium is given regardless of serum calcium levels.
Sodium bicarbonate may cause shifting of potassium into muscle cells via various mechanisms. By alkalinizing the serum, bicarbonate may indirectly cause movement of potassium into cells via an H+/K+ exchange mechanism
Beta-2 agonists have been shown to decrease serum potassium levels via an inward shift of potassium into the cells due to an effect on the membrane-bound Na/K-ATPase, which can potentially result in hypokalemia.
KAYEXALATE binds potassium in the lumen of the gastrointestinal tract.
Hypokalemia causes?
Contributing Factors
-Preoperative
GI Losses
Lasix
Magnesium deficiency
-Intraoperative
Alkalosis
Insulin therapy
Hypothermia
Notes:
Magnesium deficiency impairs Na-K-ATPase, which would decrease cellular uptake of K+
Exogenous insulin can induce mild hypokalemia because it promotes the entry of K+ into skeletal muscles and hepatic cells by increasing the activity of the Na+-K+-ATPase pump
Hypokalemia: Signs and symptoms
Cardiac conducting system abnormalities:
-Acute hypokalemia causes hyperpolarization of
the cardiac cell
-May lead to ventricular escape activity, re-entrant
phenomena, ectopic tachycardias, and delayed
conduction
-Arrhythmias
PACs, PVCs
SVTs (esp. A Fib/A flutter)
-Metabolic alkalosis
-Autonomic lability
Weakness, DTRs
Ileus
Enhanced response to muscle relaxants
Hypercalcemia Contributing Factors?
-Hyperparathyroidism
-Malignancy
-Immobilization
-Drugs
-In primary hyperparathyroidism, one or more of
the parathyroid glands is overactive. As a result,
the gland makes too much parathyroid hormone
(PTH). Too much PTH causes calcium levels in your
blood to rise too high,
-immobilization resulting from acute spinal cord
injury stimulates osteoclastic bone resorption. This
process causes calcium loss from the bones and
hypercalciuria.
Drugs - thiazide diuretics, lithium, supplements
Hypercalcemia Signs and Symptoms?
-EKG changes (short QT)
-Hypertension
-Polyuria
Hypercalcemia treatment?
-Hydration + Lasix diuresis
-Dialysis
Hypocalcemia Contributing Factors?
-Preoperative
Hypoparathyroidism
Renal failure
Sepsis
Magnesium deficiency
-Intraoperative
Alkalosis
Massive pRBC transfusion
Drugs
Ca2+ influx from the blood into the intercellular space and Ca2+ release into ascites fluid may cause hypocalcemia in sepsis and that this process may be due to the synergistic effect of endotoxin and cytokines
Hypocalcemia in chronic renal failure is due to two primary causes - increased serum phosphorus and decreased renal production of 1,25 (OH)2 vitamin D. The former causes hypocalcemia by complexing with serum calcium and depositing it into bone and other tissues.
Magnesium is required for the production and release of parathyroid hormone, so when magnesium is too low, insufficient parathyroid hormone is produced and blood calcium levels are also reduced
Alkalosis promotes the binding of calcium to albumin and can reduce the fraction of ionized calcium in the blood
Drugs - estrogen, loop diuretics, bisphosphonates, antibiotics
Hypocalcemia Hypocalcemia: Signs and symptoms?
-EKG: prolonged QT, bradycardia
-Hemodynamics
Hypotension
decreased myocardial contractility
LV failure
-Respiratory
Laryngospasm
Bronchospasm
Respiratory arrest
-Neuro
Cramps
Tetany
seizures
Hypermagnesia Contributing Factors?
-Renal failure
-Hypothyroidism
-Iatrogenic (tocolysis)
Calcium antagonizes the toxic effect of magnesium, and these ions electrically oppose each other at their sites of action.
Hypermagnesia Signs & Symptoms?
-EKG (widened QRS, prolonged PR interval,
bradycardia)
-Hemodynamics (vasodilation, hypotension,
myocardial depression)
-Neuro (DTRs, sedation, weakness, enhanced
neuromuscular blockade)
Hypomagnesia Signs & Symptoms?
-Usually asymptomatic alone, but symptomatic in
combination with induced hypokalemia,
hypocalcemia, and hypophosphatemia
-EKG (prolonged QT, PACs, PVCs, and A-Fib)
-Neuro (neuromuscular excitability, AMS, seizures)
Summary EKG changes
