Electrolyte imbalance Flashcards
What is the most abundant cation
Potassium
Potassium
Intra/extra cellular
Composition?
Intracellular
- 70% = skeletal muscle
- 30% = Liver/RBCs
How is potassium cleared
Kidneys
What are 3 ways Potassium can have an intracellular shift?
- Hormones (insulin, catecholamines, aldosterone)
- Acid-base balance
- Serum osmolality
What are 4 primary causes of hyperkalemia
- Increased K+ intake
- Decreased K+ excretion (renal failure, drugs, adrenal insufficiences)
- Redistribution of K+ to ECF
(metabolic acidosis, DM, lactic acidosis, renal failure, + Beta Blockers) - Tubular unresponsiveness to aldosterone
What does the ECG show for the following K+ levels
5.5-6.5
6.5-8.0
8.0+
5.5-6.5
- peaked T waves
- prolonged PR segment
6.5-8.0
- Loss of P wave
- ST segment elevation
8.0+
- QRS complex widens and merges with T wave
Other than cardiac arrhythmias, what are other clinical presentation of hyperkalemia (5)
- Paralysis
- Respiratory difficulutes
- Constipation
- AKI
- Generalized weakness
What are the 5 treatment options for hyperkalemia with doses
(cardiac help)
1. Calcium Gluconate 1g IV over 5-10 min
(Shifting K+ levels)
2. Regular insulin 5-10 units IV with 50mL 50 % dextrose
3. Salbutamol 10-20mg nebulized over 10 min
4. Sodium bicarb 50-100 mE1 IV over 2-5 min IF METABOLIC ACIDOSIS
(clearance)
5. Furosemide 20-40mg PO/IV
T/F Calcium gluconate expected drop in K+ is negligible
True
Which hyperkalemia treatment can actually worsen arrhythmias
Salbutamol
- tachyarrhythmia
What are ADRs of the following hyperkalemia
Calcium (2)
Insulin (1)
Furosemide
Calcium
- hypercalcemia
- tissue necrosis due to extravasation
Insulin
- hypoglycemia
Furosemide
- AKI
- Hypo Ca, Mg, K
- Ototoxicity
When would you draw the next set of labs to see if K+ is corrected when using calcium gluconate
1 hour after
Causes of hypokalemia (4)
- Direct loss of K+ from GI fluids (vomiting, diarrhea)
- Metabolic ALKALOSIS from H+ loss
- Plasma volume contraction
- Drugs
Clinical presentation of hypokalemia (6)
- ASCENDING paralysis
- Respiratory difficulties
- ECG changes
- Constipation
- AKI
- Fatigue, weakness, cramps, rhabdomyolysis
What do the following K+ levels show in sx
2.5-3
<2.5
<2.0
2.5-3: may NOT see physiological effects (treat patient not number)
<2.5: risk of rhabdomyolysis & acute renal failure
<2.0: ascending paralysis with subsequent risk of respiratory failure
What is the treatment for Hypokalemia
- Choose a salt (Cl, Bicarb (pH), Phosphate)
- Consider route of administration - ORAL or IV
- Only give IV if patient cannot tolerate PO or if patient’s disease is life-threatening - Consider dosing
Every 0.3mmol drop from normal requires 100meq replacement.
Step 4: Considerations for IV administration
- Dosing depends on type of IV access
- In life threatening scenarios, higher concentrations & rates of infusions can be used
IV administration dose for hypokalemia
Peripheral access
Central access
Peripheral access
- 10mEq added to 100mL
*Infused over 1 hour
Central access
- 40mEq added to 100mL (4x dose)
*Infused over 1-2 hours
When would you repeat labs for hypokalemia
in 30 min
What are causes of hypomagnesemia (2)
Lab #
1.GI losses
Diarrhea, bowel resection, pancreatitis, malnutrition
2.Renal losses
Volume expanded state, chronic IV fluid, hypercalcemia, diabetes
Mg < 0.7
Clinical presentation of hypomagnesemia
Mainly CNS:
- carpopedal spasm
- seizures, vertigo, ataxia, weakness
- depression, psychosis
GI: Dysphagia
CV: Ventricular arrhythmias, T wave inversion, QRS widening, PR prolongation, increased sensitivity to glycosides, ECG changes
Metabolic: atherosclerosis, hyperinsulinism, CHO intolerance
Musculoskeletal: osteoporosis, osteomalacia
Other: hypocalcemia, HYPOKALEMIA, anemia
What is the relationship between Mg and K
We cannot effectively replace K levels without correcting Mg
What is the treatment for hypomagnesemia
- Magnesium glucoheptonate liquid 100mg/mL
- Magnesium complex tablets
- Magnesium sulphate injection
*IV absorption of magnesium is saturable (Cannot exceed 1g/hour)
Causes of hypermagnesemia
Usually iatrogenic (caused by drugs or med exam)
Common causes
- AKI
- Magnesium ingestion
What is clinical presentation of hypermagnesemia (5)
Hypotension
Bradycardia
Respiratory depression
Depressed mental status
ECG abnormalities
