Fluid and Electrolyte Disturbances Flashcards
Body water is distributed between 2 major fluid compartments separated by cell membranes: _____ and _____.
ICF and ECF
ECF can be divided into what compartments?
intravascular and interstitial
The insterstitium includes what?
All fluid that is both outside cells and outside the vascular endothelium
What is used to exchange Na for K?
membrane-bound adenosine triphosphate (ATP) dependent pump
What is the ratio Na is exchanged for K?
3:2
Where is potassium concentrated intracellularly or extracellulary?
Intracellular
Where is sodium concentrated intracellularly or extracellulary?
extracellularly
What is the most important determinant of intracellular osmotic pressure?
Potassium
What is the most important determinant of extracellular osmotic pressure?
Sodium
Interference with the Na-K-ATPase activity occurs during ____ or ____. WHat does it cause?
ischemia or hypoxia; progressive swelling of cells
Intravascular volume is ECF or ICF?
ECF
Why are changes in ECF volume related to changes in total body sodium content?
Sodium is a major determinant of extracellular oxsmotic pressure and volume
T/F: Interstitial fluid is in teh form of free fluid.
false - very little interstitial fluid is normally in teh form of free fluid
Interstitial water is in a chemical association with extracellular ____-, forming a ___.
proteoglycans; gel
Is interstitial fluid pressure positive or negative?
Negative
What happens when interstitial pressure rises due to interstitial volume increase?
It becomes positive - and free fluid in teh interstitial gel matrix increases rapidly and the result is expansion only of the interstitial fluid compartment
Why is the protein content of interstitial fluid low?
only small quantities of plasma proteins can normally cross capillary clefts
How is protein that enters the interstitial space returned to the vascular system?
the lymphatic system
______ fluid is commonly referred to as plasma.
Intravascular fluid
Most electrolytes can freely pass between ___ and ____.
(intravascular) plasma; interstitium
____ is the random movement of molecules due to their kinetic energy and is responsible for the majority of fluid and solute exchange between compartments.
Diffusion
Rate of diffusion depends on what 4 things?
- Permeability of that substance
- concentration difference between 2 sides
- pressure difference between either side (pressure imparts greater kinetic energy)
- electrical potential across membrane
___,___, ____, and ____ can penetrate the cell membrane directly.
O2, CO2, water, and lipid-soluble molecules
T/F: Cations such as Na, K, and CA penetrate the lipid membrane poorly and can diffuse only through channels.
True
___ and ___- diffuse with the help of membrane-bound carrier proteins.
Glucose and amino acids
What is the normal adult daily water intake?
2500 mL
What is daily water loss average of the adult?
2500 mL
___ mL lost in urine
1500 mL
____ mL in respiratory tract evaportion
400 mL
___ mL in skin evaporation
400 mL
___ mL in sweat
100 mL
____ ml in feces
100 mL
Evaporative loss accounts for what percentage of heat loss?
20-25%
How is sodium serum concentration maintained between 136 and 145?
by the aciton of vasopressin on water and osmolal hemoestasis
What are early signs of hyponatremia?
anorexia, nausea, malaise
What are late signs of hyponatremia?
seizures, brain herniation
How do you treat hypovolemic, hyponatremia?
Volume resusciation wtih NS
How do you treat euvolemic or hypervolemic hyponatremia?
Withhold free water and encourage free water excertion with loop diuretic
Do you correct acute symptomatic hyponatremia quickly or slowly?
Quickly
Do you correct chronic symptomatic hyponatremia quickly or slowly?
Slowly
Why do you correct chronic symptomatic hyponatremia slowing?
To avoid the risk of osmotic demyelination
What is the main risk for induction of maintenance of anesthesia in hypovolemic hyponatremic patients?
HYPOTENSION
How is benign prostatic hyperplasia treated?
TURP
What does TURP stand for?
transurethral resection of the prostate
What is the irrigating fluid used during TURP?
a nearly isotonic nonelectrolyte fluid containing glycien or a mix of sorbitol and mannitol
What are the risks of irrigation during TURP?
Volume overload and hyponatremia b/c the irrigating fluid can be absorbed rapidly via open venous sinuses in the prostate gland
What 4 things increase the risk of TURP Syndrome?
- resection >1. hour
- irrigating fluid >40cm
- hypotonic irrigation fluid
- pressure in bladder >15
Resection longer than ____ is associated with increased risk of TURP syndrome.
1 hour
Irrigating fluid suspended higher than ____ above the operative field is associated with increased risk of TURP syndrome.
40 cm
HYpertonic or hypotonic irrigation fluid is associated with increased risk of TURP syndrome?
Hypotonic
Bladder pressure >____ is associated with increased risk for TURP syndrome.
15 cmH2O
What are 2 common findings in TURP syndrome?
HTN and pulmonary edema
What is the treatment for TURP syndrome?
Stop surgery, administer loop diuretics, and hypertonic saline (w/ severe neuro s/s or Na<120)
Hypernatremia induces the movement of water across the cell membrane into teh ___.
ECF
What are early S/S of hypernatremia?
restlessness, irritability, lethargy
What are late S/S of hypernatremia?
muscular twitching, hyperreflexia, tremors, ataxia
S/S of muscle spasitcity, seizures, and death occur with hypernatremia when the osmolaity increases above ___.
325
S/S of hypernatremia are more severe with acute or chronic high sodium levels?
acute
How is hypovolemic hypernatremia treated?
Water deficit is replenished with NS or electrolyte solution
How is hypervolemic hypernatremia treated?
Diuresis with loop duretic
How is euvolemic hypernatremia treated?
PO water replacement or 5% Dextrose IV
Acute hypernatremia should be corrected over _____.
several hours
Chronic hypernatremia should be corrected over ____.
2-3 days
What happens if you correct chronic hypernatremia too quickly?
cerebral edema
Potassium plays a major role in regulating membrane potential as well as in ___ and ___ synthesis.
carbohydrate and protein
Renal excretion of potassium can. vary from ___ to ___ mEq/L.
5-100
Nearly all the potassium filtered in glomeruli is normally reabsorbed in the ____________ and ________.
proximal tubule and loop of henle
T/F: Plasma potassium concentration typically correlates poorly with the total potassium deficit.
True
When does hypokalemia due to the intracellular movement of potassium occur?
alkalosis, insulin therapy, beta agonists, hypothermia, and hypokalemic periodic paralysis
What are renal related causes of hypokalemia?
Hypomagnesemia, renal tubular acidosis, ketoacidosis, salt-wasting nephropathies, amphotericin B
Why is hypokalemia due to decreased potassium intake not common?
B/c of the kidneys ability to decrease urinary potassium excretion to as low as 5-20
Most patients are asymptomatic with hypokalemia until K falls below ____.
3
What are the CV effects of hypokalemia?
abnormal EKG, arrhythmias, decreased contractility, liable BP (d/t autonomic dysfunction)
What type of IV solutions should be used with hypokalemia and why?
Glucose-free; b/c glucose stimulates K+ movement into the cell
Hyperventilation or hypoventilation should be avoided with hypokalmia?
Hyperventilation
There might be an increased sensitivity to ____ drugs with hypokalemia.
NMB
When does hyperkalemia occur due to extracellular movement of potassium?
acidosis, cell lysis following chemo, hemolysis, rhabdo, massive tissue trauma, hyperosmolality, digitalis OD, hyperkalemic periodid paralysis, Sux, BB, and arginine hydrochloride
When does hyperkalemia due to decreased renal excretion of potassium occur? (3)
- reduced GFR
- Decreased aldosterone activity
- defect in K+ secretion in the distal nephron
Skeletal muscle weakness with hyperkalemia is generally not seen until K+ is >____
8
Cardiac manifestations of hyperkalemia are due to ______.
delayed depolarization
Cardiac manifestations are consistently present when plasma K+ level is >_____
7
Because of its lethal potential, hyperkalemia exceeding ___ should always be corrected.
6
Which is stronger Calcium chloride or gluconate?
chloride
What is the dose of calcium gluconate for hyperkalemia?
5-10 mL of 10% calcium gluconate
What is the dose of calcium chloride for hyperkalemia?
3-5 mL of 10% calcium chloride
_______ partially antagonizes the cardiac effects of hyperkalemia and is useful in symptomatic patients with marked hyperkalemia.
Calcium
What potentiates Digoxin toxicity?
Calcium
Only ___% of total body calcium is present in ECF. Where is the rest stored?
1; bone
What calcium is physiologically active?
ionized calicum in the extracellular space
Ionized calcium concentrations are affected by _____ concentration and ___.
albumin; pH of plasma
What 3 hormones regulate calcium metabolism?
- parathyroid
- calcitonin
- vitamin D
How does parathyroid hormone regulate calcium?
increases bone reabsorption and renal tubular reabsorption of calcium
How does calcitonin regulate calcium?
inhibitis bone resorption
How does vitamin D regulate calcium?
augments intestinal absorption of calcium
_____ reduceds the iCa concentration, so therefore, iCa may be significantly reduced after _______ administration.
alkalosis; bicarbonate
Significantly reduced iCa may be seen with hyperventilation or hypoventilation?
hyperventilation
What are S/S of hypocalcemia?
Paresthesias, irritability, seizures, hypotension, myocardial depression
What is an electrolyte concern in the post-op period following thyroid or parathyroid resection?
Hypocalcemia-induced laryngospasm
How do you treat acute symptomatic hypocalcemia (seizures, tetany, CV depression)?
IV calcium
Treatment of hypocalcemia in teh presence of ____ is ineffective.
hypomagnesmia
(Mg must also be replenished)
If acidosis is present with hypocalcemia, what should be corrected first?
Calcium level (b/c correcting acidosis w/ bicarb or hyperventilation will exacerbate hypocalcemia)
What is normal iCa level?
1.1-1.2
At what iCa level should you treat hypocalcemia?
0.8 or less
At an iCa of ____ S/S will occur.
0.7
Sudden decreases in iCa level may be seen in early post-op period after ___ or _____ surgery. What can this cuase?
thyroidectomy or parathyroidectomy; laryngospasm
A decrease in iCa levels should always be considered during MTP of blood containing ____.
citrate
When does hypercalcemia occur?
- increased GI absorption
- decreased renal excretion
- increased bone resorption
When does increased calcium absorption from teh GI tract occur?
- milk-alkali syndrome
- vitD intoxication
- granulomatous disease such as sarcoidosis
When does increased bone resorption of calcium occur?
primary or secondary hyperparathyroidism
hyperthyroidism
immobilization
What are S/S of hypercalcemia?
confusion, hypotonia, depressed DTR, lethargy, abdominal pain, N/V
Hypercalcemia is frequently associated wtih hyper or hypovolemia? This is secondary to _____.
hypovolemia; poluria
What is the anesthetic management for emergency surgery in the patient with hypercalcemia?
Restoring intravascular volume before induction and increase urinary excretion of calcium with loop diuretics
What type of diuretic should be avoided wtih hypercalcemia?
Thiazide (b/c it increases renal tubular reabsorption of calcium)
Where is magnesium predominantly found?
intracellularly and in mineralized bone
Renal reabsorption and excretion of magnesium is ____.
passive
Hypomagnesium S/S are similar to S/S of _____
hypocalcemia
What are the S/S of hypomagnesemia?
dysrhythmias, weakness, muscle twitching, tetatny, apathy, seizures
Hypomagesemia is most commonly due to what 2 things?
reduced GI uptake or to renal wasitng of mg
How can you determine which is causing hypomagnesemia - decreased GI uptake or renal wasting?
by measuring urinary Mg excretion rate
With hypomagnesemia, if cardiac dysrhythmias or seizures are present what is the treatment? Include dose.
IV bolus of 2 grams Mg Sulfate
2 grams of Mg Sulfate = ____ mEq of Mg
8
What is a potential s/e of the treatment of hypomagnesemia?
hypermagnesemia
What is the anesthesia management for patients with hypomagnesemia?
attention to S/S, Mg supplementation, and treatment of refractory hypokalemia or hypocalcemia
____magnesium can enhance digitalis toxicity.
hypo
Magnesium >___ is considered hypermagnesemia
2.5
When is Mg given?
Torsades
T/F: Mg can be briskly excreted if renal function is normal, so hypermagnesemia is much less common.
True
Magnesium infusion is sometimes done during what procedure?
Pheochromocytoma surgery
What are first S/S of hypermagnesemia?
lethargy, N/V, facial flushing
When do the S/S of lethargy, N/V, facial flushing begin with hypermagnesemia?
At levels of 4-5
For hypermagnesemia, At levels >___, loss of DTR and hypotension occur.
6
At Mg levels >6, ____ and ___ occur.
loss of DTR and hypotension
What are 2 meds (besides IV Mg Sulfate) that could cause high Mg?
antacids and Mg-based enemas or cathartics
How can life-threatening signs of hypermagenesmia be temporarliy treated?
IV Calicum
How can mild forms of hypermagnesemia be treated?
Loop diuretics and diuresis with salien
_____ exacerbates hypermagnesemia so careful attention must be paid to ventilation and arterail pH.
Acidosis
Does acidosis or alklaosis exacerbate hypermagnesemia?
Acidosis
Phosphorus is required for the synthesis of what 3 things?
- phospholipids and phosphoproteins in cell membranes
- phosphonucleotides involved in protein synthesis and reproduction
- ATP used for storage of energy
Hyperphosphatemia may be seen with ____ syndrome.
tumor lysis
What are examples of increased phosphorus intake associated with hyperphosphaemia?
abuse of phosphate laxatives or excessive admin of potssium phosphate
Significant hyperphosphatemia may produce ____ (other electrolyte imbalance).
hypocalcemia
How does hyperphosphatemia produce hypocalcemia?
Via phosphate chelation with plasma Ca2+
Hyperphosphatemia may produce _____ via parenchymal and tubular deposits of calcium-phosphate sats.
AKI
How do you treat hyperphosphatemia?
Phosphate-binding antacids
What are the two phosphate-binding antacids?
Aluminum hydroxide or aluminum carbonate
what can cause severe hypophophatemia?
- Large doses of aluminum or Mg containing antacids
- severe burns
- insufficient Phos supplementation durign TPN
- DKA
- Alcohol withdrawal
- prolonged respiratory alklaosis
____ mg/dL is considered mild to moderate hypophosphatemia
1.5-2.5
T/F: Mild to moderate hypophosphatemia is generally asymptomatic.
True
Severe hypophosphatemia is considered a phosphorus level <___.
1.0 mg/dL
Sever hypophophatemia is associated with increased ______ in critically ill.
morbidity and mortality
Is PO or parenteral phosphorus replacemetn preferred?
PO
Why is PO phosphorus preferred over parenteral?
B/c of the increased risk of phosphate precipitation w/ Ca
What is a post-op concern wtih severe hypophosphatemia?
Some pts may require mechanical ventilation b/c of muscle weakness