Fluid/Electrolytes (Unfinished) Flashcards
Isotonic
-Same concentration of active solutes as extracellular fluid
-Prevents fluid shift between compartments
-(275-290 mOsm/L)
Hypotonic
-Less concentrated than extracellular fluid
-Fluid moves into the cell, causing increased cellular volume
-(< 275 mOsm/L)
Hypertonic
-More highly concentrated than extracellular fluid
-Fluid is pulled into bloodstream from cells
-(>290 mOsm/L)
Tonicity of crystalloids
Isotonic, hypotonic, hypertonic
Examples of crystalloids
-NS
-1/2 NS
-D5W
-LR
-Balanced salt solutions
Tonicity of colloids
Hypertonic
Examples of colloids
-Albumin
-Hetastarch
-Tetrastarch
-Blood
-Plasmanate
Functions of crystalloid solutions
Provide water and/or sodium
-Maintain osmotic gradient between intravascular and extravascular compartments
NS place in therapy
-Used for intravascular fluid replacement (resuscitation)
-Sodium and/or chloride replacement
1/2 NS place in therapy
Used for maintenance fluids (combination products)
Lactated ringers place in therapy
-Used for replacement of blood loss
-Approximates human plasma
-Used for resuscitation (trauma, burn, etc.)
D5W
-Used for free water replacement
-Not a resuscitative fluid
-Not a maintenance fluid by itself
Functions of colloid solutions
Used to increase plasma oncotic pressure
Move fluid from the interstitial compartment to the intravascular (plasma) compartment
What is the most common maintenance IV fluid?
-D5W+1/2NS+20mEq kCl/L
-Used to increase plasma oncotic pressure
-Similar composition to urine
Possible signs of dehydration
-Decreased skin turgor
-Dry mucus membranes
-Delayed capillary refill
-Tachycardia and hypotension
-Peripheral pulses weak
-Decreased urine output (<0.5 mL/kg/hr), dark urine
-BUN/SCr ratio > 20 (may mean dehydration)
Osmolarity of NS
154 mEq/L
Pseudohyponatremia (isotonic)
-Extreme elevations of lipids and proteins increase the total plasma volume
-Can be seen with hypertriglyceridemia or hyperproteinemia
-Leads to dilution effect
-Sodium appears low
Hypovolemic hypotonic hyponatremia
Decrease in both total body water and sodium
Hypovolemic hypotonic hyponatremia renal causes
-Diuretics/excess diuresis
-Adrenal insufficiency (mineralocorticoid deficiency)
-Salt losing nephropathy
-Cerebral salt wasting
Hypovolemic hypotonic hyponatremia non-renal causes
-Blood loss/hemorrhage
-Skin losses
-GI losses
Isovolemic hypotonic hyponatremia
-Increased TBW and normal or slightly increased total body Na+
-Slight excess of ECF
-No peripheral or pulmonary edema
-Clinically appears euvolemic
Isovolemic hypotonic hyponatremia causes
-Adrenal insufficiency (glucocorticoid deficiency)
-Hypothyroidism
-Psychogenic polydipsia
-SIADH
Drugs that can induce SIADH
-Antipsychotics
-SSRIs
-Carbamazepine
Treatment of SIADH
-Remove underlying cause if possible
-First line: free water restriction
-Vaptans may be beneficial if 24-48 hours of free H2O restriction fails “aquaretics”
Hypervolemic Hypotonic Hyponatremia
-Total body Na+ is increased but TBW increases even more
-Expanded ECF volume and edema
Clinical presentation of hypovolemic hypotonic hyponatremia
-Dehydration
-Decreased skin turhor
-Orthostatic hypotension
-Tachycardia
-Dry mucous membranes.
Clinical presentation of isovolemic hypotonic hyponatremia
-Discomfort
-Psychosis
-Seizures
-Coma
Clinical presentation of hypervolemic hypotonic hyponatremia
-Fluid overload
-Edema and weight gain
Clinical presentation of acute hyponatremia (over 12 hrs or less)
-Nausea
-Discomfort
-Weakness
-Headache
-Disoriented
-Coma
-Seizures
-Respiratory arrest
Goal of treatment for hypotonic hyponatremia
In most cases the goal is to avoid rise in serum sodium > 0.5 mEq/L/hr or no more than 8-12 mEq/L/day
Treatment options for hypovolemic hypotonic hyponatremia
-3% NaCl if symptomatic
-0.9% NaCl if asymptomatic
Treatment options for isovolemic hypotonic hyponatremia
-Furosemide and 3% NaCl if symptomatic
-0.9% NaCl if asymptomatic and water restriction
Treatment options for hypervolemic hypotonic hyponatremia
-Furosemide and judicious 3% NaCl in symptomatic patients
-Furosemide in asymptomatic patients
Acute hyponatremia
-<48 hours
-Brain swell with water
-Cerebral edema
-Severe neurological symptoms
-Brain herniation
-Death
Chronic hyponatremia
-Brain cells extrude solutes
-Minimal brain swelling
-Mild neurological symptoms
-Brain herniation is rare
-Death is rare
Treatment of acute symptomatic hyponatremia
-Increase serum Na+ by 1-2 mEq/L/hr until symptoms resolve
-Reasonable short-term Na+ goal = 120 mEq/L
-Complete correction is unnecessary
-If corrected too rapidly it will lead to diffuse demyelinating lesions
-Generally, an increase of 4-6 mEq/L is sufficient to reverse most acute manifestations
-Maximum increase of 8-12 mEq/L in the first 24 hours
-Treat with 3% saline and replace half of sodium deficit in 8 hours then other half with 8-16 hrs
Hypovolemic hypernatremia
Loss of H2O and Na+
Isovolemic hypernatremia
Loss of H2O
Hypervolemic hypernatremia
Gain of H2O and Na+
Hypovolemic hypernatremia treatment
-Restore hemodynamic status first if needed (maybe with 0.9% NaCl)
-Once intravascular volume has been restored calculate free water deficit
Isovolemic hypernatremia treatment
-Desmopressin
-Vasopressin
Hypertonic hypernatremia treatment
-Stop the hypertonic fluids/cause
-Rapidly excreted
-Diuretic if needed
Factors that affect potassium levels
-Na/K ATPase pump
-Kidneys
-Arterial pH / acid-base status
Causes of hypokalemia
-Diuretic loss (potassium-wasting)
-Beta-agonist medications
-NG drainage
-Metabolic alkalosis
-Diarrhea
Magnesium depletion
Clinical presentation of hypokalemia
-Nonspecific and highly variable
-Weakness
-Nausea/vomiting
-Changes in cardiac function / arrhythmias
-Cramping
-Impaired muscle contraction
-Cardiac patients may be at higher risk (HTN, MI, HF)
Goals of therapy for hypokalemia
-Prevent and treat serious complications, cardiac arrhythmias
-Normalize serum potassium concentration
-Identify and correct underlying cause
-Prevent overcorrection/hyperkalemia
Treatment when potassium level is 3.5 – 4 mEq/L
-No therapy generally recommended
-Goal in ICU is often greater than or equal to 4 mEq/L
Treatment when potassium level is 3 – 3.4 mEq/L
-Treatment debatable
-PO potassium for patients with cardiac conditions
<3 mEq/L
-Always treat
-PO route is preferred in asymptomatic patients
-IV for symptomatic patients or patients who cannot take PO
IV K+ warnings/precautions
-Thrombophlebitis and pain at infusion site
-Higher risk of leading to hyperkalemia/overcorrection
-Arrhythmia or cardiac arrest if given too quickly
IV K+ administration
-Generally each 10-20 mEq is diluted in 100 mL of D5W
-Infusion rate without cardiac monitoring: 10 mEq/hr
-With continuous cardiac monitoring:
-20 mEq/hr
-40-60 mEq/hr if emergent with severe hypokalemia
Hyperkalemia clinical presentation
Peaked T wave at 5.5-6 mEq/L
Steps to treat severe hyperkalemia
- Antagonize the membrane actions
- Decrease extracellular K+ concentrations
- Remove K+ from the body
C A BIG K DROP
-Calcium
-Albuterol
-Bicarb
-Insulin + glucose
-Kayexalate/Lokelma
-Diuretics
-Renal unit for dialysis of patient
Treatment for chronic hyperkalemia
Patiromer (Valtassa)
Drugs that can cause hypomagnesemia
-Amphotericin
-Aminoglycosides
-Diuretics (thiazide or loop)
-Cyclosporine
-Alcohol
Which other electrolyte abnormalities is hypomagnesemia associated with?
-Hypocalcemia
-Hypokalemia
Treatment of asymptomatic hypomagnesemia patients
PO
-Milk of mag
-Mag-Ox
Treatment of symptomatic hypomagnesemia patients
IV
-When Mg2+ 1-2 mg/dL: 0.5 mEq/kg
-When Mg2+ < 1 mg/dL: 1 mEq/kg
-Infuse 1 gram per hour
-Also use for patients who cannot tolerate PO
Acute treatment of hypocalcemia
-100-300 mg elemental Ca2+ IV over 5-10 min
-Usual administration rate is 1 gm/hr
-Do not add to bicarb or phos solutions
-Correct hypomagnesemia
Is chloride or gluconate better for IV push administration?
Gluconate is preferred for IV push but chloride can still be used during code
Chronic treatment for hypocalcemia
-PO calcium such as Tums
-Vitamin D supplementation such as Calcitriol
Mild to moderate hypophosphatemia treatment
-Oral PO4
-Phos-NaK
-Fleets Phospho-Soda
-Give PO doses as divided
Treatment for severe hypophosphatemia
-IV PO4
-Use KPhos when K+ < 4 mEq/L
-Use NaPhos when K+ is greater than or equal to 4 mEq/L
-Infuse IV doses no faster than 7 mMol/hr
