Chp. 3 Electrolytes Flashcards
What types of electrolyte abnormalities do you typically see with an acidosis?
Hyperkalemia
Hypercalcemia (ionized)
Hyperchloremia
What types of electrolyte abnormalities do you typically see with an alkalosis?
Hypokalemia
Hypocalcemia (ionized)
Hypochloremia
What types of electrolyte abnormalities do you typically see with CHF?
Hyponatremia with hypervolemia (check)
What types of electrolyte abnormalities do you typically see with hypoadrenocorticism?
Hyponatremia
Hyperkalemia
Hypercalcemia
What types of electrolyte abnormalities do you typically see with hyperadrenocorticism?
Hypernatremia
What types of electrolyte abnormalities do you typically see with hypoparathyroidism?
Hypocalcemia
What types of electrolyte abnormalities do you typically see with hyperparathyroidism (primary or secondary)?
Hypercalcemia
What types of electrolyte abnormalities do you typically see with hyperaldosteronism?
Hypernatremia
Hypokalemia
What types of electrolyte abnormalities do you typically see with DI?
Hypernatremia
What types of electrolyte abnormalities do you typically see with vomiting?
Hypochloremia
Hyponatremia or Hypernatremia
Hypokalemia
What types of electrolyte abnormalities do you typically see with GDV?
Hypochloremia
What types of electrolyte abnormalities do you typically see with diarrhea?
Hyponatremia or Hypernatremia
Hyperchloremia
Hypomagnesemia
Hypokalemia
What types of electrolyte abnormalities do you typically see with anorexia?
Hypokalemia
Hypomagnesemia
What types of electrolyte abnormalities do you typically see with PLE?
Hypocalcemia +/- hypomagnesemia
What types of electrolyte abnormalities do you typically see with equine colic?
Hypocalcemia
Hypomagnesemia
What types of electrolyte abnormalities do you typically see with pancreatic disease?
Hypocalcemia
Hypomagnesemia
Hyponatremia
What types of electrolyte abnormalities do you typically see with eclampsia?
Hypocalcemia
What types of electrolyte abnormalities do you typically see with parturient paresis?
Hypocalcemia
What types of electrolyte abnormalities do you typically see with acute renal failure?
–Hypocalcemia
–Oliguric Phase: hypernatremia, hyperkalemia, hypermagnesemia
–Diuretic phase: hyponatremia, hypokalemia, hypomagnesemia
What types of electrolyte abnormalities do you typically see with chronic renal failure?
–With polyuria: hypermagnesemia, hypokalemia (cats), hypocalcemia (dogs, cats), hypercalcemia (dogs, cats, horses)
–With oliguria: hyperkalemia
What types of electrolyte abnormalities do you typically see with renal tubular acidosis?
Hypokalemia
What types of electrolyte abnormalities do you typically see with nephrotic syndrome?
Hyponatremia (with hypervolemia)
What types of electrolyte abnormalities do you typically see with urinary tract obstruction?
hyperkalemia
What types of electrolyte abnormalities do you typically see with ruptured bladder, uroabdomen?
Hyperkalemia
Hyponatremia (foals)
What types of electrolyte abnormalities do you typically see with ethylene glycol poisoning?
Hypocalcemia
What types of electrolyte abnormalities do you typically see with peritoneal dialysis?
Hypomagnesemia
Hypokalemia
What types of electrolyte abnormalities do you typically see with myositis?
Hyperkalemia
What types of electrolyte abnormalities do you typically see with tissue destruction?
Hyperkalemia
What types of electrolyte abnormalities do you typically see with burns?
Hyperkalemia
What types of electrolyte abnormalities do you typically see with HYPP in QH?
Hyperkalemia
What types of electrolyte abnormalities do you typically see with anal sac apocrine gland adenocarcinoma?
Hypercalcemia
What types of electrolyte abnormalities do you typically see with lymphoma?
Hypercalcemia
What types of electrolyte abnormalities do you typically see with multiple myeloma?
Hypercalcemia
What types of electrolyte abnormalities do you typically see with other endocrine neoplasias?
Hypercalcemia
What types of electrolyte abnormalities do you typically see with dehydration?
Hypernatremia
Hyperchloremia
Hypercalcemia
What types of electrolyte abnormalities do you typically see with hypoalbuminemia?
Hypocalcemia
What types of electrolyte abnormalities do you typically see with blood transfusion (citrate)?
Hypocalcemia
Hypomagnesemia
What types of electrolyte abnormalities do you typically see with excessive dietary supplementation in large animals?
Hypercalcemia
What types of electrolyte abnormalities do you typically see with excessive dietary supplementation in small animals?
Hypernatremia
Hyperkalemia
Hypercalcemia
What types of electrolyte abnormalities do you typically see with hypervitaminosis D?
Hypercalcemia
What types of electrolyte abnormalities do you typically see with hypertonic fluid administration?
Hypernatremia
What types of electrolyte abnormalities do you typically see with hyPOkalemic periodic paralysis in Bermese cats?
Hypokalemia
What types of electrolyte abnormalities do you typically see in young animals?
Hypercalcemia, hyperphosphatemia
What types of electrolyte abnormalities do you typically see in cats that could be idiopathic?
Hypercalcemia
What types of electrolyte abnormalities do you typically see following thyroidectomy?
Hypocalcemia
What types of electrolyte abnormalities do you typically see with parathyroidectomy for parathyroid gland tumor removal??
Hypocalcemia
Which antibiotics can cause electrolyte abnormalities and what do they cause?
Aminoglycosides: hypomagnesemia
Cyclosporine: hyperkalemia
Penicillins: hypokalemia
Which dietary supplements can cause electrolyte abnormalities and what do they cause?
–Salt substitute: hyperkalemia
– Laxative/antacid: hypermagnesemia
Which diuretics can cause electrolyte abnormalities and what do they cause?
–Potassium-sparing (spironolactone, triamterene, amiloride): hyperkalemia
–Loop diuretics: hypochloremia, hypocalcemia, hypokalemia, hypomagnesemia
Which positive inotropes can cause electrolyte abnormalities and what do they cause?
–Digitalis: relative hypomagnesemia by shifting Mg into the cell -> Mg deficiency will magnify effect of digitalis tox
–Catecholamines: hypomagnesemia, hypokalemia
What electrolyte abnormalities are seen with ACE-I?
Hyperkalemia
What electrolyte abnormalities are seen with insulin?
Hypokalemia
What electrolyte abnormalities are seen with steroids?
Hypocalcemia
What electrolyte abnormalities are seen with Na bicarbonate?
Hypernatremia
Hypocalcemia
Hypokalemia
What electrolyte abnormalities are seen with mannitol?
Hypernatremia
What BP effects do you see with hypocalcemia?
Effect not determined -> can see both hypotension DT vasodilation, hypertension in human patients
What BP effects do you see with hypercalcemia?
–VC –> patients with VC may have extreme response to anesthetic agents that cause VD, resulting in profound hypotension DT relative hypovolemia under GA
What BP effects do you see with hypokalemia?
Hypotension DT decrease in SVR
What BP effects do you see with hypomagnesemia?
-Hypertension -> patients with hypertension may have extreme response to drugs that cause vasodilation, resulting in profound hypotension under ax
What BP effects do you see with hypermagnesemia?
-Causes decrease in peripheral vascular resistance
-Myocardial contractility probably not affected by elevated magnesium concentrations
What cardiac changes effects do you see with hypocalcemia?
Occurrence of ECG changes not consistent in hypocalcemic patients
What ECG/cardiac changes will you see with hypercalcemia in awake animals?
- Rarely causes clinically significant cardiac problems in awake animals
What ECG/cardiac changes will you see with hypercalcemia in anesthetized animals?
- Changes in cardiac electrical activity may occur –> prolongation of PR interval, shortening of QT interval bradycardia, AV block, and cardiac arrest
What ECG/cardiac changes will you see with hypokalemia?
- Bradycardia
- SV, ventricular arrhythmias
- Prolonged QT interval
- ST segment deviations
- Decreased amplitudes of T waves
- Development of U waves
- Delayed ventricular repolarization
- Increased duration of the AP
T/F: Patients with hypokalemia are unresponsive to the effects of class I anti-arrhythmics
True!
What ECG/cardiac changes will you see with hyperkalemia?
- Peaked T waves
- Decreased in size of P waves, R waves
- Prolonged P-R interval
- Widened QRS complexes
- Bradycardia typically present with higher K+ concentrations (>7.0), though some patients present with vtach
What ECG/cardiac changes will you see with hypermagnesemia?
- Bradycardia
- 3rd degree AV block
- Asystole
- Widening QRS complexes
What ECG/cardiac changes will you see with hypomagnesemia?
- Peaked T waves
- Mild ST segment depression
- Prolonged P-R interval
- Widened QRS complexes
- Atrial fibrillation
- ventricular tachycardia
- SVT
- Torsades de pointes
- Ventricular bigeminy
- VPCs
- Ventricular fibrillation
How do you treat arrhythmias caused by low magnesium under GA?
- Should resolve once the inhalant anesthetic turned off and patient recovers from anesthesia
How do treat arrhythmias due to hypomagnesemia with magnesium sulfate?
- If rate control necessary in presence of atrial fibrillation or ventricular arrhythmias
- 0.15-0.3mEq/kg dilute to <20% solution with 5% dextrose in water administered over 5-15 minutes
What concurrent administration will negate the effects of magnesium sulfate?
- Concurrent administration of calcium
What is true about magnesium sulfate and NMBAs?
- Mg may increase neuromuscular blockade when used concurrently with non depolarizing NMBA
What clinical changes can be seen in anesthetized patients associated with electrolyte abnormalities?
- Cardiac arrhythmias
-most significant
-Can develop under GA in previously unaffected animals - Hypotension
- Delayed recovery
What do you see with patients that are hypotensive due to electrolyte abnormalities?
- Patients with pre-existing EL disorders more commonly have hypotension that is unresponsive to fluid administration
- Lightening of ax depth results in patient movement with minimal improvement in MAP
Why can you see delayed recovery in patients with electrolyte abnormalities?
- EL abN that result in muscle weakness will potentially cause delay
- Ex: hyperkalemia, hypokalemia, hypercalcemia, hypocalcemia (majority of cases present with muscle fasciculations, tetany), hypermagnesemia, hypomagnesemia
When is treatment for electrolyte abnormalities indicated in ax’d patients?
- Most EL abnormalities should be diagnosed, corrected prior to GA
- When not possible, ax agents that potentiate cardiac arrhythmias should be avoided
Which anesthetic agents are most arrhythmogenic and should be avoided in patients with pre-existing electrolyte abnormalities?
- Halothane
- Barbiturates
- alpha 2 agonists
T/F: every effort should be made to prevent changes in electrolytes that may be caused by GA
True!
Why is it advantageous to use IPPV to control PCO2 levels in an animal with mild hyperkalemia and UTO?
- Want to prevent exacerbation of the respiratory acidosis, which could worsen hyperkalemia by shifting K+ from inside to outside the cell
How will an acidosis affect iCa levels?
Increases iCa levels –> avoid in hypercalcemic patient
How will an alkalosis affect iCa levels?
Decreases iCa levels
What is the maximum rate to correct K+?
0.5mEq/kg/hr
(Study questions describes rate of 0.5-1mEq/kg/hr) –> patients with more severe potassium deficits will tolerate potassium administration rates at the upper end of the dose range
How should you administer K+ under GA?
Be sure to concurrently administer fluid with N K+ so that in the event of acute blood loss, fluids may be bolused without exceeding maximum safe rate for potassium administration
What is the maximum concentration of potassium that can be administered via a peripheral catheter?
60mEq/L
Anything more than that should be administered through a central line
What are the two main mechanisms for decreasing potassium in an anesthetized patient?
- Increasing elimination of K in urine
- Shifting EC K into IC compartment
What agents can be used to decrease K levels?
- K-free fluids
- NaBicarb
- Insulin, glucose
- Calcium
What is the approximate serum potassium concentration at which you start to see cardiac arrhythmias?
- 6-7mEq/L
How administer potassium-free fluids to decrease potassium levels?
Typically 0.9% NaCl used at 10-40mL/kg/hr
How administer NaBicarb to decrease potassium levels?
- Ideally administer based on ABG
- Can give 0.5-1.0mEq/kg IV if A/VBG data is unavailable and patient unlikely to have pre-existing metabolic alkalosis
How administer insulin, glucose to decrease potassium levels in dogs and cats?
- 0.5-1.0U regular insulin per kg BW with 2g dextrose per unit insulin can be given to dogs to shift K IC
- Use lower end of dose range in cats
What is the benefit or reason to use calcium in a hyperkalemic patient?
- TREATMENT DOES NOT ACTUALLY DECREASE SERUM POTASSIUM
- Used to block adverse CV effects caused by hyperkalemia
- Normalizes relationship btw resting membrane potential and threshold potential
How administer insulin, glucose to decrease potassium levels in horses and foals?
0.05-0.15U/kg IV regular insulin followed by infusion of 5% dextrose 4.4-6.6mL/kg with an initial rate of 0.1-0.2mL/kg/min
How can you use dextrose alone to correct K+?
- Admin of 5% dextrose without insulin = slower but may also be effective in correcting hyperkalemia in SA, horses with HYPP
- Technique effective at decreasing K within 15-30min of administration, lasts several hours
What is the mechanism of using calcium in hyperkalemic patients?
DOES NOT DECREASE SERUM POTASSIUM
-Hyperkalemia raises (makes less negative) resting membrane potential (RMP) of cell membranes
-As RMP gets closer to threshold potential, cell depolarizes more easily –> hyper excitability
-As RMP continues to rise, approaches threshold potential –> cells then take longer to repolarize, resulting in bradycardia
- Ca administration increases threshold potential, moving it further above RMP, therefore normalizing relationship btw RMP and threshold potential
How can anesthesia increase blood potassium levels in an anesthetized patient?
- All ax agents decrease sensitivity of brain to elevated PaCo2
- Decrease = dose-related –> more severe with some ax agents (opioids, barbiturates, iso, sevo) than others (ether, halothane, ketamine)
-Impt to closely monitor under GA, avoid excessive ax depth, ventilate if have pre-existing EL abnormalities to avoid respiratory acidosis, which can increase serum concentrations of K and Ca
What is the breakdown of Ca in the body?
Total calcium consists of:
- Protein-bound calcium (35%)
-iCa (55%)
-Complexed Ca (10%)
What is another agent/group of drugs that can cause a transient hyperkalemia?
Depolarizing muscle relaxants/NMBA (eg succinylcholine)
How do depolarizing muscle relaxants cause hyperkalemia?
- Can cause release of K from m cells, esp when repeatedly admin
- Prior admin of diazepam can prevent this increase, should be used in hyperkalemic patients when succinylcholine must be given
What are some fluid therapy guidelines for patients with hypernatremia?
- fluid admin to hypernatremic patient, esp one with concurrent dehydration, can result in cerebral edema if change in serum Na occurs too rapidly
- Dehydrated patients requiring ax should receive an isotonic fluid with Na concentration similar to that of normal plasma
- Typically, hypernatremia resolves with correction of dehydration
If hypernatremia does not resolve with correction of dehydration, how might one provide fluid therapy to this patient?
- 0.45% NaCl with 2.5% dextrose or 5% dextrose in water can be given slowly while serum Na concentrations serially monitored to ensure decrease no faster than 0.5-1mEq/hr
-Typically can be achieved using fluid rate of 3-6mL/kg/hr, depending on Na [ ] in administered fluid
What are some fluid therapy guidelines for patients with hyponatremia?
- Occur slowly, 0.5-1mEq/hr using isotonic crystalloid solution (eg LRS)
- Use of more concentrated (up to 3% NaCl sln) more controversial
- Esp important to treat this EL abN during or after ax hen signs of cerebral edema are present
What are signs of cerebral edema?
- Absence of palpebral reflex
- Papillary edema
- Hypertension
What is papillary edema?
Edema or swelling of the optic disc secondary to increased ICP
What happens with aggressive treatment of hyponatremia, esp chronic hyponatremia?
- Can result in an irreversible, fatal condition known as osmotic myelinosis
- CS Assoc with this condition do not develop for 1-3d
Normal serum Na for dogs and cats? (INCLUDE UNITS IN ANSWER)
mEq/L
Dog: 145-152
Cat: 151-158
Normal serum Cl for dogs and cats? (INCLUDE UNITS IN ANSWER)
mEq/L
Dog: 107-113
Cat: 117-123
Normal serum K for dogs and cats? (INCLUDE UNITS IN ANSWER)
Dogs, cats: 3.5-5.3 mEq/L
Normal serum iCa for dogs and cats? (INCLUDE UNITS IN ANSWER)
mmol/L:
–Dogs: 1.2-1.5
–Cats: 1.1-1.4
mg/dL:
–Dogs: 5.0-6.0
–Cats: 4.5-5.5
Normal total Ca for dogs and cats? (INCLUDE UNITS IN ANSWER)
mmol/L:
–Dogs: 2.2-2.3
–Cats: 2.0-2.6
mg/dL:
–Dogs: 9.0-11.5
–Cats: 8.0-10.5
Normal iMg for dogs and cats? (INCLUDE UNITS IN ANSWER)
Dogs: 1.04-1.36 mg/dL
Normal total Mg for dogs and cats? (INCLUDE UNITS IN ANSWER)
Dogs: 1.7-2.4
Cats: 1.7-2.7
Levels at which you should correct Na?
Dog: >165, <135
Cat: >165, <145
Levels at which you should correct Cl?
Tx required only when acid/base changes excessive:
–Hyperchloremia with pH <7.2
–Hypochloremia with pH >/= 7.48
Levels at which you should correct potassium?
> 6.5, <2.5
Levels at which you should correct iCa?
Dog: >7.0, <5.0 mg/dL
Cat: >6.5, <4.5
Levels at which you should correct tCa?
Dog: >14.5, <6.5
Cat: >13.5, <7.0
Levels at which you should correct iMg?
Dogs: <0.8mg/dL
Levels at which you should correct tMg?
Dog: <1.2mg/dL
How does albumin affect the total calcium level measured in serum?
- albumin = predominant protein bound to Ca (80-90%)
- Changes in serum albumin will change measured total serum calcium
- Adjusting total serum calcium level to account for this variation is particularly important when serum albumin level is outside of the normal range
What is the equation to adjust total serum Ca based on albumin?
Adjusted Ca (mg/dL) = Measured Ca (mg/dL) - albumin (g/dL) + 3.5
What are the limitations of the formula to adjust total serum Ca based on albumin?
- Not used to adjust for changes in albumin in young dogs or cats
- True that in these patients that decreases in albumin are associated with decreases in serum calcium, but that a linear relationship does not exist
How fast can Ca be administered in hypocalcemic dogs and cats?
-If have cardiac signs of hypocalcemia, tx with bolus of 10% CaGlu 0.5-1.0mL/kg slowly over 10-20min period while monitoring ECG
- Can give additional CaGlu at 0.05-0.15mgkghr slowly with concurrent ECG monitoring if repeated measurements of iCa remain below normal
-Correction of cardiac arrhythmia all that required during ax
How is calcium divided within the body?
- Protein-bound Ca (35%)
- iCa (55%)
- Complexed Ca (10%)
What influences the percentage of serum calcium in the ionized and protein-bound states?
-pH of the blood –> alkalosis causing a decrease in iCa, acidosis causing an increase in proportion of Ca in ionized form
Which is the biologically active form of calcium?
ionized Ca
When is it recommended to measure iCa?
- clinical signs of hypocalcemia or disease states causing hypocalcemia are present even when total calcium concentrations are normal –> iCa can be abnormal in face of normal total serum Ca level
What is the purpose of looking at total serum calcium?
- usually used to assess calcium status of an animal, even though iCa is the ionized form
How fast can you give calcium to hypocalcemic horses?
- 23% CaGlu can be admin slowly @ 0.25-0.5mL/kg/hr while monitoring ECG for evidence of bradycardia
-Concurrent administration of dobutamine through same IVC acceptable in hypotensive horses if Ca and dobutamine not added to same bag of fluids
Does a parathyroidectomy have an acute effect on blood calcium levels?
Yes!
Because PTH responsible for minute-to-minute adjustments in iCa concentration in the body and short half life in the serum, removal of PTH glands potentially has an acute effect on blood Ca levels
What is the role of parathyroid hormone?
Minute to minute adjustments in serum iCa in the body
What is the half-life of PTH in serum?
3-5’
Parathyroidectomy in Cats
-Cranial parathyroid glands external to the thyroid parenchyma
-Can be dissected free of the thyroid gland prior to removal
Parathyroidectomy in Dogs
-May result in partial or complete removal of the PT gland in dogs, since both cranial and caudal parathyroid glands are embedded in body of each thyroid lobe
What is another risk of patients that have a parathyroid tumor removed?
–Risk extreme fluctuations in serum iCa levels bc of pre surgical suppression of the normal gland’s PTH production by excessive PTH production by the tumor
–In these cases, hypocalcemia frequently noted within 12-120hrs after sx
How often should a patient’s blood calcium concentration be measured after a parathyroidectomy?
-Baseline Ca should be established immediately postoperatively
-Reassess at current levels (Q6hrs) for up to 5d or until Ca fluctuations have stabilized
-Tx postoperative hypocalcemia should be acutely done using IV Ca preparations administered slowly while patient is carefully monitored
How keep cat on maintenance rate of IV calcium once clinical signs of hypocalcemia resolve?
-10mL of 10% Ca gluconade added to 250mL LRS
-Admin 60mL/24hr
How keep dog on maintenance rate of IV calcium once clinical signs of hypocalcemia resolve?
-10mL of 10% Ca gluconade added to 250mL LRS
-Admin 1.25mL/kg/hr
What is the PO dose calcium lactate/calcium carbonate?
25mg/kg/day elemental Ca
Should administer with vitamin D
At what point can you discontinue supplemental Ca following parathyroidectomy?
Requires adequate time for ectopic parathyroid tissue to hypertrophy (2-3 weeks) or damaged parathyroid glands to revascularize
What percentage of total body magnesium is serum magnesium?
<1%
What are the three distinct fractions of serum magnesium?
- Complexed with anions (12%)
- iMg (55%)
- Protein-bound (33%)
Which fraction of Mg is considered to be biologically active?
iMg
Where is the vast majority of the body’s Mg stored?
- Intracellularly –> measurement of serum magnesium thought to be a poor reflection of the magnesium stores in the body
-Serum [Mg] obtained from commercial laboratory analysis of serum most readily available sample for determination of Mg concentration
T/F: serum Mg levels can be normal in the face of low total body Mg
True
Which is more common in critically ill dogs or cats - hypo or hypermagnesemia?
Hypomagnesemia
What is the reason behind giving patients in various types of shock (noncardiogenic) hypertonic saline?
- Rapidly increase blood volume
What formulations of hypertonic saline are available?
Alone (7.2% NaCl) or in combination with 6% Dextran 70
How is hypertonic saline dosed?
4-6mL/kg –> reports of safe administration of up to 10 mL/kg to animals in hemorrhagic shock
Which appears to have a longer duration of action - 7% NaCl with dextran or regular NaCl?
with dextran
What see when give 7% NaCl at recommended dosing to a patient with normal blood electrolytes?
- Serum sodium will rise above normal value but should stay below 165mEq/L, serum osmolality increases to near 360mOsm/kg
- Changes generally well tolerated
- VPCs commonly observed, but transient
What is the concern with administered 7.2% NaCl at a dose greater than 6mL/kg?
- Proceed with caution bc run the risk of increasing Na concentration to >165mEq
In which patients 7.2% NaCl contraindicated?
-Pre-existing hypernatremia
-Dehydration
-Hyperosmolality
What might you see if you give 7.2% NaCl faster than 1mL/kg/min?
- Vagally-mediated bradycardia
- Hypotension
- Rapid shallow breathing
- Bronchoconstriction
- Signs will disappear once infusion rate has been slowed
What is HYPP?
Hyperkalemic Periodic Paralysis of QHs and Cross-Breeds
What clinical signs are associated with HYPP?
- Muscle fasciculations
-Weakness
-Third eyelid prolapse - Tachypnea
- Inspiratory stridor
- laryngospasm
- dysphagia
- Recumbency
- Death
What clinically is the difference between homozygote and heterozygote HYPP horses?
- Homozygous horses tend to show more extreme clinical signs that appear earlier in life