Potassium K disorders Flashcards
Normal Distribution of Potassium in the Body
ICF: 98% to 99% located in the intracellular compartment.
140 mEqL/ vs 4 mEq/L
Hypokalemia <
feline hyperaldosteronism
3.5mEq/L
heightened awareness - as the cause of marked hypokalemia
secondary aldosteronoma or adrenocortical hyperplasia
hypokalemia are divided into four categories:
Most notable metabolic:
metabolic, neuromuscular, renal, and cardiovascular
Glucose intolerance is the most notable adverse metabolic effect of hypokalemia.
impairs release of insulin from the pancreatic β cells
when total body potassium levels are decreased
CV C/S assoc. hypoK and MoA:
neuromuscular signs are seldom present until serum potassium levels fall below ____
K necessary for maintenance of RMP from hyperpolarized (less excitable) myocyte plasma membranes that may progress to hypopolarized membranes
most significant neuromuscular abnormality skeletal muscle weakness, ventroflexion, stiff, stilted gait, plantigrade stance
resp. paralysis and death of diaphragmatic failure and respiratory muscle failure, rhabdomyolysis, smooth muscle impairment = paralytic ileus and gastric atony
2. 5 mEq
HypoK ECG findings:
will lidocaine work in face of hypoK?
high intracellular/extracellular K ratio
= state of electrical hyperpolarization
= prolongation of AP
- predispose atrial and ventricular tachyarrhythmias (tiggered activity EAD/DADs?)
- atrioventricular dissociation
- ventricular fibrillation
ECG findings in hypokalemia less reliable than hyperkalemia
- depression of the ST segment
- prolongation of the QT interval
- increased P wave amplitude
- prolongation of the PR interval
- widening of the QRS complex
predisposes to digitalis-induced cardiac arrhythmias
causes the myocardium to be refractory to class I antiarrhythmic agents (i.e., lidocaine, quinidine, and procainamide)
no
Kmax and units
<2.5mEq/kg/hr in 1 L = 80mEqKcl = max rate you can run
0.5 mEq/kg/hr HOUR
serum potassium < 2.5 mEq/ rate can be increased cautiously to 1 to 1.5 mEq/kg/hr along with close ECG
6ml/kg/hr
Why must you fluid resusc. DKA prior to insulin and HCO3-:
postponed for the first 4 to 8 hours, or until the serum potassium level is greater than 3.5 mEq/
Failure to do so can lead to marked, life-threatening hypokalemia secondary to translocation into the intracellular space
ddx for refractory hypoK (3):
- metabolic alkalosis
- hypomagnesemia
- hypocalcemia coexist
Hyperkalemia ____ mEq/L and is considered life threatening ____ mEq/L
- 5 mEq/L
7. 5 mEq/L
hyperK four basic disturbances:
- increased intake or administration
- translocation
- decreased renal excretion
- artifactual or pseudohyperkalemia
Increased Intake or Supplementation
- Intravenous potassium-containing fluids
- Expired RBC transfusion
- Translocation from ICF to ECF
- Acute tumor lysis syndrome
- Extremity reperfusion
Decreased Urinary Excretion
- Anuric or oliguric renal failure
- Urethral obstruction
- Hypoadrenocorticism
- Gastrointestinal disease (trichuriasis, salmonellosis)
- Chylothorax with mechanical drainage
- Drugs (ACE inhibitors, spironlolactone/potassium-sparing diuretics, nonspecific β-blockers)
Pseudohyperkalemia
- Thrombocytosis or leukocytosis
- Akita dog and other dogs of Japanese origin
DKA
- osmotic diuresis = decreases TBK
- hyperkalemia: decreased cellular uptake secondary to insulin deficiency
- extracellular translocation w water bc serum hyperosmolality (“solute drag”)
- increased protein catabolism, prerenal azotemia, and any coexisting renal impairment
ECG:
- muscle weakness can occur when the serum potassium concentration exceeds 7.5 mEq/
- bradycardia or atrial standstill
- due to prolonged depolarization and repolarization of the myocardial conduction system
- ECG findings do not correlate precisely with serum potassium concentrations since the rate of increase or decrease also plays a role
Pseudohyperkalemia
why Akita dogs:
- K can be released from increased numbers of circulating blood cells, especially platelets and white blood cells- primarily in animals with severe thrombocytosis or leukocytosis
- Akita dogs (or other dogs of Japanese origin) secondary to in vitro hemolysis
- because their erythrocytes have a functional Na/KATPase as such, have high intracellular potassium concentrations
hyperkalemia if hemolysis in serum
confirmation of pseudohyperkalemia via normal plasma potassium concentration (blood collected in a heparinized tube) because this should not be affected by changes in platelet or white blood cell numbers (unless the patient suffers from leukemia)
diuretics to decrease K
Loop (furosemide 1 to 4 mg/kg intravenously [IV]) or thiazide (chlorothiazide 20 to 40 mg/kg PO) diuretics can increase urinary potassium excretion
Terbutaline
25% Dextrose with insulin
10% Calcium gluconate
Stimulates Na+/K+-ATPase to cause translocation of potassium into the cell 20min onset
Allows for translocation of potassium into the intracellular space
Increases threshold voltage but will not lower serum potassium
