Electrolyte Abnormality Flashcards
Highest sodium concentration that should be allowed before cancelling an elective surgery
150 mEq/L
Lowest sodium concentration that should be allowed before cancelling an elective surgery
130 mEq/L
3 things that happen when sodium is reabsorbed
- Water is reabsorbed and blood volume increases
- Bicarb and chloride are reabsorbed and can lead to metabolic alkalosis
- Potassium is excreted, leading to hypokalemia
Acidosis caused by excess N/S administration
Hyperchloremic metabolic acidosis (w/normal anion gap)
What happens in RAAS if a patient becomes hypotensive or hypovolemic (5 steps)
- Renin is secreted from the kidneys
- Renin converts angiotensinogen to angiotensin I
- ACE converts angiotensin I to angiotensin II
- Angiotensin II increases blood pressure (vasoconstriction and release of aldosterone and ADH)
- ADH causes water reabsorption, while aldosterone causes sodium AND water reabsorption
Increases sodium AND water reabsorption
Aldosterone
What happens when aldosterone is released? (4 things)
- Plasma sodium concentration increases
- Blood volume increases
- HCO3- increases possible metabolic alkalosis
- Plasma potassium concentration decreases
What happens when ADH is released?
- Increases water reabsorption
- Blood volume increases
- Plasma sodium concentration decreases
What happens with Cushing’s disease?
- Aldosterone increase
- increased blood volume/hypertension
- Hypernatremia
- Hypokalemia
- metabolic alkalosis - Steroid/cortisol concentrations increase
- hyperglycemia
What happens with Addison’s Disease?
Adrenal insufficiency
- aldosterone decreases
- hypovolemia/hypotension
- Hyponatremia
- Hyperkalemia
- Metabolic acidosis - Decrease in cortisol
- hypoglycemia
Occurs when there are increased aldosterone concentrations, but normal cortisol levels
Hyperaldosteronism
Clinical manifestations of hyperaldosteronism may include
- Hypokalemia
- Hypernatremia
- Increased blood volume and blood pressure
- Metabolic alkalosis
Treatment for hyperaldosteronism
Potassium sparing diuretics
Occurs when there are decreased aldosterone concentrations, but normal cortisol
Hypoaldosteronism
Cause of hypoaldosteronism
Renal failure
Clinical manifestations of hypoaldosteronism
- Hyponatremia and hyperkalemia
2. Metabolic acidosis
Hypernatremia is defined as ____
> 145 mEq/dL
Etiologies of hypernatremia
- Retention of sodium
2. Dehydration where water loss is greater than sodium loss
Symptoms of hypernatremia
- Brain cell shrinkage
- Increased MAC requirements
- Hypertension
- Hyperreflexia and possible weakness
- Potentiation of the effects of muscle relaxants
Treatment of hypernatremia
- Hypotonic fluid
- Loop diuretics
TREAT SLOWLY
How do you calculate water deficit in hypernatremic patients?
Water deficit = normal total body water - present total body water
How do you estimate normal total body water?
Patients weight in kg x percentage of body weight that is water = TBW
(Normal TBW)(Normal [Na+]) = (present [Na+])(x)
Water deficit for hypernatremic patients should be replaced over ____
48 hours
Occurs when the posterior pituitary fails to secrete ADH
Central diabetes insipidus
How is central diabetes insipidus treated?
- Hypotonic fluids
- DDAVP
- Thiazide diuretics
Occurs when the kidneys do not respond to ADH
Nephrogenic diabetes insipidus
Treatment of nephrogenic diabetes insipidus
- Hypotonic fluids
2. Thiazide diuretics
Plasma sodium concentration considered hyponatremic
<135 mEq/dL
Etiologies of hyponatremia
- Retention of water
2. Dehydration where sodium loss is greater than water loss
Possible symptoms of hyponatremia
- Cerebral edema
- Altered mental status
- Muscle weakness
Examples of hyponatremia from water retention
- SIADH
2. AIDs
How does the body compensate for hyponatremia in a euvolemic or hypervolemic patient?
By suppressing ADH release
Treatment of hyponatremia
Give sodium
- Find out how many mEq/L the patient is deficient in sodium
- Find out how many total mEq the patient is deficient in sodium using TBW
How much sodium is in 0.9% of NS?
154 mEq/L
What can happen with rapid hyponatremia treatment?
- Central pontine myelinolysis
- Pulmonary edema
- Hypokalemia
- Hyperchloremic acidosis
Max daily rate of sodium correction
10-12 mEq/L
Why can’t a surgeon use normal saline for irrigation with TURP?
Saline disperses the electrocautery current
Advantages to performing TURP with a laser
- Normal saline can be used as an irrigation solution
- Less blood loss
- Shorter hospital stay
Disadvantages to TURP with a laser
- Longer operation times
2. May not effectively remove most or all of BPH tissue
Possible irrigation solutions used for TURP
- Distilled water (rare, extremely hypotonic)
- 0.9% normal saline (not used with cautery)
- Glycine (can lead to possible transient visual impairment)
Most common type of dehydration in children
Isonatremic
Highest potassium concentration that should be allowed before cancelling an elective surgery
5.5 mEq/L
Lowest potassium concentration that should be allowed before cancelling an elective surgery
2.8 mEq/L
What does insulin do to potassium?
Drives potassium intracellularly and DECREASES plasma K+ concentration
What do beta agonists do to potassium?
Decreases plasma K+ concentration
Acidosis leads to (hypokalemia/hyperkalemia)
Hyperkalemia
Hypokalemia can lead to (acidosis/alkalosis)
Alkalosis
Alkalosis can lead to (hypokalemia/hyperkalemia)
Hypokalemia
Hyperkalemia can lead to (acidosis/alkalosis)
Acidosis
Etiologies of hyperkalemia
- Acidosis & beta blockers
- Succinylcholine
- RBC transfusions
- Cell lysis
- Renal and adrenal insufficiency
- ACE inhibitors
- Rewarming following hypothermia
What is seen on an EKG with hyperkalemia?
- Peaked T waves
- Smaller P amplitude
- Increased PR interval
- Widened QRS
- Eventual sine wave EKG and possible vfib/asystole
Symptoms of hyperkalemia
- EKG changes
2. Muscular weakness
Hyperkalemic treatment pneumonic
CBIGKD (see big kid)
- Calcium
- Bicarb
- Insulin
- Glucose
- Kaexylate
- Diuretic/dialysis
Temporary treatments for hyperkalemia
- Shifting K+ intracellularly
2. Stabilize myocytes with calcium
Insulin rate for treatment of hyperkalemia
5g dextrose per 1 unit of insulin (1 amp dextrose per 5 units of insulin)
How long does calcium stabilize myocytes?
15-30 minutes before requiring redose
Permanent treatment for hyperkalemia
- Kaexylate
- Diuretics
- Dialysis
Hypokalemia etiologies (9)
- Insulin administration
- Diuresis/diuretic therapy
- Sympathetic stimulation/increase in circulating catecholamines
- Alkalosis
- Red blood cell transfusions
- Dialysis
- GI loss/small bowel obstruction and/or vomiting
- Hypothermia
- Hypomagnesemia
Hypokalemia EKG
- T wave flattened or inverted
2. U waves appear
Symptoms of hypokalemia
- EKG changes
2. Muscle weakness
Hypokalemia treatment
100 mL NS bag with 20 mEq potassium infused with infusion pump
Amount of potassium to give with peripheral IV access
8-10 mEq/hr
Amount of potassium to give with central line access
20 mEq/hr
How much will 20 mEq of potassium increase the plasma level by?
0.25 mEq/L
How long will it take to increase the plasma potassium concentration by 1.0 mEq/L
4 hours
What should you be cautious of with the treatment of hypokalemia?
- Avoid dextrose replacement solutions, as insulin will secrete and lower potassium more
- Avoid aggressive treatment in hypothermia and head trauma
Etiologies of hyperchloremia
- Metabolic acidosis
2. Excess normal saline administration
Etiologies of hypochloremia
- Bowel obstruction or N/V
- Diuretic therapy
- Respiratory acidosis
- Administration of sodium without chloride (sodium bicarb)
Pediatric patients with pyloric stenosis can present with
- Vomiting, leading to metabolic alkalosis
- Hypochloremia
- Hypokalemia
Why should LR be avoided in pyloric stenosis?
Lactate is metabolized to bicarb and can worsen the alkalosis
What fluid is used in pyloric stenosis?
Normal saline
How is pyloric stenosis managed?
Electrolyte disturbances are corrected
Why are patients with pyloric stenosis prone to hypoventilation after anesthesia?
Hypoventilation is the normal compensatory response to their metabolic alkalosis
Effects of PTH
Decreases bone calcium and increases plasma calcium concentration
Effects of calcitonin
Decreases plasma calcium concentration and increases bone calcium
Etiologies of hypercalcemia
- Hyperparathyroidism
- Acidosis
- Cancer
Possible effects of hypercalcemia (7)
- Shortened QT interval on EKG
- Muscular weakness
- Osmotic diuresis leading to hypovolemia
- Potentiation of muscle relaxants
- CNS symptoms
- Hypomagnesemia
- Renal stones
Treatment for hypercalcemia
- Treat hypovolemia with normal saline
- Give loop diuretic
- Calcitonin
- Dialysis
- Avoid acidosis
Etiologies of hypocalcemia
- Hypoparathyroidism
- Hypermagnesemia
- Vitamin D deficiency
- Renal failure
Effects of hypocalcemia
- Prolonged QT interval on the EKG
- Hyperreflexia and muscular tetany (laryngeal stridor, masseter spasm, laryngospasm)
- Muscle weakness and potentiation of muscle relaxants
- CNS symptoms
Treatment for hypocalcemia
IV calcium chloride or calcium gluconate
Etiologies of hypermagnesemia
Renal failure (rare, caused by medication or health care provider)
Possible effects of hypermagnesemia
- EKG may resemble hyperkalemia (shortened QT interval, prolonged PR interval, T wave abnormalities)
- Muscular hyporeflexia and weakness
- Potentiation of nondepolarizing muscle relaxants
- Hypocalcemia can occur
- CNS symptoms
- Hypotension
Treatment for hypermagnesemia
- IV calcium chloride
- Loop diuretic
- Volume expansion
- Potential dialysis
Etiologies of hypomagnesemia
- Decreased GI absorption
- Increased renal loss
- Hypercalcemia
Possible effects of hypomagnesemia
- EKG findings??
- Muscular weakness and potentiation of muscle relaxants
- CNS symptoms
- Hypokalemia
Treatment for hypomagnesemia
1-2 g magnesium sulfate over 10 minutes
Electrolyte abnormalities that can cause hyperreflexia AND possible weakness
- Hypernatremia
2. Hypocalcemia
Electrolyte abnormalities that cause muscle weakness
- Hyponatremia
- Hyperkalemia
- Hypokalemia
- Hypercalcemia
- Hypomagnesemia
Electrolyte abnormalities that cause HYPOreflexia and weakness
- Hypermagnesemia
Electrolyte abnormalities that potentiate muscle relaxants
- Hypernatremia
- Hypokalemia
- Hypercalcemia
- Hypocalcemia
- Hypermagnesemia
- Hypomagnesemia
Electrolyte abnormalities that cause hypovolemia
- Hypercalcemia
Electrolyte abnormalities that can occur with hypovolemia
Hyper and hyponatremia
Electrolyte abnormalities that can cause hypotension
- hyperkalemia
- Hypocalcemia
- Hypermagnesemia
- Hypomagnesemia
Electrolyte abnormalities that can cause hypertension
- Hypercalcemia
Electrolyte abnormalities that can cause CNS symptoms
- Hypernatremia
- Hyponatremia
- Hypercalcemia
- Hypocalcemia
- Hypermagnesemia
- Hypomagnesemia