Module 1 - Fluids, Electrolytes, and Acid-Base Balance Flashcards
Total body water is __ % of total body weight
60
Intracellular fluid is __% of total body water
67
Extracellular fluid is __% of total body water
33
Plasma is ___% total body water
6.6
Interstitial fluid is ___% of total body water
26.4
Plasma and interstitial fluid make up ??
extracellular fluid
What is blood plasma?
Yellow liquid component of blood that suspends whole blood cells, proteins, glucose, clotting factors, electrolytes, hormones and CO2
What is blood serum?
Blood plasma WITHOUT the clotting factors (fibrinogen, prothrombin)
Na+ and Cl- are high _____ of the cell
outside
K+ is high _____ the cell
inside
Why are fluids important?
- To maintain homeostasis (euvolemia)
- To replenish the fluids lost through normal physiologic activities
What are insensible losses? Examples?
Losses we can’t see or measure:
- perspiration
- respiration
What are sensible losses?
Examples?
Losses we can see and measure:
- urination
- feces
- wound drainage
- GI losses
To maintain fluid balance, the average person requires ________mL of water per day
2000-3000
Hypertonic
[solute] > serum
*draws fluid out of the cell and into the intravascular space
Isotonic
[solute] = serum
*fluid stays in the intravascular space
Hypotonic
[solute] < serum
*fluid shifts out of the intravascular space and into the cell
Hypertonic solution is __% NaCl
3% NaCl (513 mmol/L)
Isotonic solution is __% NaCl
0.9% NaCl (154 mmol/L)
Hypotonic solution is __% NaCl
0.45% NaCl (77 mmol/L)
Serum contains ______ mmol/L of Na+
145
See slide 9 for calculating serum osmolality
ok
Why do we care about calculating serum osmolality?
- Highly concentrated solutions are irritating to veins (phlebitis) or can damage tissue
- Depending on concentration, may require central line access (a larger vessel)
Replacing fluids:
Resuscitation
patient is clearly volume depleted
Replacing fluids:
Maintenance
patient is NPO (nothing by mouth), poor oral intake
What is the recommended fluid replacement for resuscitation?
Give fluid bolus of 500 mL crystalloid (Na+ 130-154 mmol/L) over 15 minutes (can repeat up to 2000mL)
What is the recommended fluid replacement for maintenance ?
Normal daily fluid and electrolyte requirements:
- 25-30mL/kg/day water
- 1 mmol/L/kg/day Na+, K+, Cl-
- 50 - 100 g/day of glucose
*Works out to approximately 100-120 mL/hr
What are electrolytes?
substances that ionize when’d dissolved in solvents such as water
What do electrolytes do?
- Maintain the body’s fluid balance and osmolality
- Maintain the body’s pH balance
- Maintain proper fcn of cells
Na+ is most abundant in ______ fluid (maintained by Na+/K+ ATPase pump)
extracellular
______ results in water entering cells
Hyponatremia
_____ results in water getting drawn out of cells
Hypernatremia
Abnormal sodium levels usually indicate a problem with _____ balance
water
Sodium balance is mainly controlled by the ________ with the help of aldosterone, ADH and atrial natriuretic peptide
KIDNEY
Describe what happens if sodium level is low (or low blood pressure)
- Anti-diuretic hormone is released from posterior pituitary gland
- Aldosterone is released
- Kidney reabsorbs Na+ and water
Describe what happens if sodium level is high (or high blood pressure)
- Atrial natriuretic hormone is released from the heart
- Kidney excretes Na+ and water
What levels constitute mild hyponatremia?
130-135 mmol/L
What levels constitute moderate hyponatremia?
125 - 129 mmol/L
What levels constitute severe hyponatremia?
< 125 mmol/L
Symptoms of hyponatremia?
- asymptomatic
- impaired attention
- gait changes (trouble walking)
- falls
- N/V
- altered mental status
- seizures
- respiratory arrest = death
What type of medication can cause low sodium and low volume?
Diuretics (dump Na+ and water)
What types of medication can cause low sodium but normal volume?
- NSAIDs
- SSRIs
- illicit drugs
- carbamazepine
- cyclophosphamide
Treatment for low sodium/low volume?
0.9% NaCl to rehydrate patient and correct Na+
Treatment for low sodium/normal volume?
fluid restriction, diuresis (loop diuretics)
Treatment for low sodium, too much fluid?
fluid restriction, diuresis (loop diuretics)
Formula for sodium deficit?
Sodium deficit = [0.6 x weight(kg)] x (desired Na+ - actual Na+)
For sodium correction: Correct no more than ________
9 mmol/L/day
What level constitutes severe hypernatremia?
> 160 mmol/L
Symptoms of hypernatremia?
- thirst
- lethargy
- restlessness
- irritability
- ataxia
- tremors
- seizures
- coma
Treatment for hypovolemic hypernatremia?
fluids (D5W or 0.2% NaCl in D5W)
Treatment for euvolemic hypernatremia?
vasopressin (ADH)
*THIS DOESN’T MAKE SENSE WTF
Treatment for hypervolemic hypernatremia?
Diuretics (get rid of Na+ and water) or dialysis
Potassium is most abundant in ______ fluid
intracellular
What is potassium important for?
proper conduction of action potentials (muscle excitability)
potassium is __% renally eliminated
90
_____ pushes K+ inside cells
insulin
______ activate Na+/K+ ATPase
B-agonists (epinephrine)
______ dump K+, keep Na+ and water
aldosterone
What is metabolic alkalosis ?
decreased K+ levels
What is metabolic acidosis ?
increased K+ levels
What levels constitute mild hypokalemia?
3.1-3.5
Symptoms of mild hypokalemia?
often asymptomatic
What levels constitute moderate hypokalemia?
2.5 - 3.0
Symptoms of moderate hypokalemia?
cramping, weakness, malaise, myalgias
What levels constitute severe hypokalemia?
< 2.5
Symptoms of severe hypokalemia?
ECG changes
What causes hypokalemia?
- excessive GI loss (vomiting, diarrhea, NG suction)
- decreased intake (malnourished)
- excessive renal loss (diuretics)
- acid-base balance (metabolic alkalosis)
Hypokalemia can cause ______ toxicity
Digoxin
What levels constitute mild hyperkalemia?
5.5 - 6.0 mmol/L
What levels constitute moderate hyperkalemia?
6.1 - 7.0 mmol/L
What levels constitute severe hyperkalemia?
> 7.1 mmol/L
Symptoms of mild hyperkalmia
usually asymptomatic
Symptoms of moderate hyperkalemia?
cardiac arrhythmias
Symptoms of severe hyperkalemia?
- cardiac arrhythmias
- weakness
- paralysis
- respiratory failure
- sudden cardiac arrest
Causes of hyperkalemia?
- excessive intake (supplements, salt substitutes)
- impaired renal function
- redistribution to extracellular fluid
- psudeohyperkalemia (hemolysed blood sample)
- DRUGS (K+ sparing diuretics, ACEi, ARBs)
- missed dialysis session
Treatment of hyperkalemia?
calcium gluconate, insulin & dextrose, salbutamol, dialysis
Caution with intravenous potassium?
K+ can cause arrhythmias and death
Max rate of K+ for peripheral line
20 mmol/hr
Max concentration of K+ for peripheral line
80 mmol/L
Max rate of K+ for central line
40 mmol/hr
Max concentration of K+ for central line?
200 mmol/L
Cl- is a major ______ anion
extracellular
What regulates chloride balance?
sodium and bicarbonate
What level is severe hypochloremia?
< 75 mmol/L
Causes of severe hypochloremia?
- severe loss of GI fluids
- metabolic alkalosis (too much bicarb) *holding onto bicarbonate which is an anion, therefore chloride is excreted and lost
- renal losses (loss of sodium, chloride follows)
- drugs (i.e. PPIs lower stomach acidity)
What level is severe hyperchloremia?
> 125 mmol/L
Causes of hyperchloremia
- sodium and water retention
- metabolic acidosis (too many H+ ions) *bicarb is excreted, H+ is retained therefore Cl- is retained
Most magnesium resides in the ______ space or in bone
intracellular
Levels of severe hypomagnesemia?
< 0.5 mmol/L
Symptoms of hypomagnesemia
neuromuscular hyperirritability (tremors, tetany, arrhythmias, seizures)
Causes of hypomagnesemia?
- reduced intestinal absorption (malnutrition, alcoholism, malabsorption syndromes)
- increased urinary/fecal losses (diarrhea, loop and thiazide diuretics)
- intracellular shifts
Levels of mild-moderate hypermagnesemia
1-1.5 mmol/L
Symptoms of mild-moderate hypermagnesemia?
usually asymptomatic
Levels of hypermagnesemia?
> 1.5 mmol/L
Symptoms of severe hypermagnesemia?
nausea, headache, drowsiness, hypocalcemia, deep tendon reflexes absent, hypotension, bradycardia, ECG changes, paralysis, death
Causes of hypermagnesemia?
- chronic kidney disease (unable to eliminate)
- excess magnesium intake
- addison’s disease (not enough mineralocorticoids)
- lithium
Treatment of hypermagnesemia?
- stop excessive intake
- IV calcium
- dialysis
Calcium found in _____ fluid
extracellular
How much calcium is free?
45% of total calcium
What is the formula for Corrected calcium?
Ca corrected = Ca serum + 0.02*(40-albumin)
Level o fever hypocalcemia?
< 1 mmol/L
Symptoms of hypocalcemia?
Muscles: myalgia, numbness, tingling, tetany, hyperreflexia
Cardiac: arrhythmias, hypotension
CNS: seizures
Causes of severe hypocalcemia?
- vitamin D deficiency
- hypoparathyroidism
- renal disease
- malabsorption or pancreatitis
- hypomagnesemia
- drug causes (bisphosphantes, calcitonin, furosemide)
Level of mild hypercalcemia?
2.6-3.0 mmol/L
Symptoms of mild hypercalcemia?
usually asymptomatic, constipation
Level of moderate-severe hypercalcemia?
> 3.0 mmol/L
Symptoms of moderate-severe hypercalcemia?
nausea, abdominal pain, constipation, kidney stones, polydipsia, polyuria, dehydration, hypertension, shortened QT intervals, stupor, coma
Causes of hypercalcemia?
- hyperparathyroidism
- malignancy
- drug causes (tamoxifen, lithium, thiazide diuretics, vitamin D)
Treatment of hypercalcemia?
- treat underlying disorder
- reduce calcium intake
- cinacalcet
- parathyroidectomy
Phosphorus found primarily in ______ space
intracellular
Level for mild-moderate hypophosphatemia
0.3 - 0.8 mmol/L
Symptoms of mild-moderate hypophosphatemia
usually asymptomatic
Level for severe hypophosphatemia
< 0.3 mmol/L
Symptoms of severe hypophosphatemia
rhabdomyolysis, hemolysis, platelet dysfunction, cardiac/respiratory failure, encephalopathy, seizures
Causes of hypophosphatemia
- inadequate intake
- increased excretion
- intracellular shift
Level for mild-moderate hyperphosphatemia
1.6 - 2.3 mmol/L
Symptoms of hyperphosphatemia?
usually asymptomatic
Level for severe hyperphosphatemia
2.4 mmol/L
Symptoms for severe hyperphosphatemia
Gi disturbance, lethargy, urinary obstruction (renal stones), red eye, pruritus
Causes of hyperphosphatemia?
- excessive intake
- decreased elimination (renal disease)
Treatment of hyperphosphatemia?
- phosphate binders (calcium carbonate, sevelamer, lanthanum)
- increase urinary excretion (acetazolamide, dialysis)
What are arterial blood gasses used to determine?
- oxygenation status
- acid-base status
pH determines?
how acidic/basic is the blood
pCO2 determines?
what the lungs are doing
HCO3 determines?
how much bicarb is in the blood
____% of total CO2 is bicarbonate
95
Acidemia
arterial pH < 7.35
Alkalemia
arterial pH > 7.45
Acidosis
a process that will result in academia if left unopposed (usually caused by decreased HCO3 and/or increased pCO2)
Alkalosis
a process that will result in alkalemia if left unopposed (usually caused by increased HCO3 and/or decreased pCO2)
Metabolic alkalosis
increased HCO3
*lungs try and retain pCO2
Metabolic acidosis
decreased HCO3
*lungs try to blow off more pCO2
Respiratory alkalosis
decreased pCO2
*kidneys try to excrete bicarbonate
Respiratory acidosis
increased pCO2
*kidneys try to retain bicarbonate
What is normal anion gap?
8-16 mmol/L
formula for anion gap
Anion gap = Na+ - [Cl- + HCO3-]