L 1-4: Fluids and Electrolytes Flashcards
IBW equations
Male: 50kg + (2.3 * over 60inch)
Female: 50kg + (2.3* over 60inch)
NBW equation
IBW + 0.25(wt-IBW)
Three main organ systems involved in fluid balance
Skin
Lungs
Kidneys
When to use NBW, and ABW
> 130% of BW = use NBW
if pt is less than IBW, use ABW
Fluid intake
Should = fluid losses
Sensible vs insensible fluid loss
Sensible: 1-1.5 L/day
Insensible 1L/day
NG output vs Diarrhea output
NG: loss of acid - alkalosis
Diarrhea: Loss of base - acidosis
Isotonic range
275-290 mOsm/L
Hypotonic and Hypertonic range
Hypo: <275 mOsmol/L
Hyper: >920 mOsmol/L
Total osmolarity equation
Total osmolarity = osmolarity of IV solution + Osmolarity of added electrolytes
0.9% NS osmolarity
154 mOsmol/L
Calculating MIVF
Clinical estimate:
30-40ml/kg/day
Crystalloids
Isotonic, Hypotonic, or hypertonic
-Flexible
NS
1/2 NS
D5W
LR
Balanced salt solutions
Colloids
Hypertonic
Albumin (5 or 25%)
Hetastarch
Tetrastarch
Blood
Plasmanate
NS place in therapy
Fluid replacement, NOT maintenance
1/2 NS place in therapy
Maintenance - lots of flexibility
LR place in therapy
Resuscitation - burns, trauma, etc
D5W place in therapy
Free water replacement
NOT maintenance by itself
Colloid solution place in therapy
Hypertonic -plasma expanders
-Get fluid out of cell into plasma
Albumin adverse effects
Hypervolemia - Too much water in body
Azotemia - too much waste in body
Albumin
Supportive/symptomatic treatment
Synthetic colloids problems
Black Box Warning: Severe sepsis
RBCs
Packed RBCs used when low hemoglobin (<7-8 g/dL)
Most common MIVF
D5W + 1/2 NS + 20 mEq KCl/L
Dehydration warning urine output
<0.5 mL/kg/hr
Hyponatremia
Most common electrolyte disturbance in hospitalized patients
-Brain injury, seizure, death
Demyelation
Pseudohyponatremia
Extreme elevations of lipids and proteins increase the total plasma volume
-Seen with hypertriglyceridemia or hyperproteinemia
-We would not treat this (overcorrecting)
Hypertonic hyponatremia
High levels of osmolality
Hypotonic hyponatremia
Most complicated
Most common - >90% of all hyponatremia
Need to assess ECF volume:
-Hypovolemic
-Isovolemic
-Hypervolemic
Osmolality
Number of particles per liter of water (mOsm/L)
Hypovolemic Hypotonic Hyponatremia
Decrease in BOTH total body H2O and Na+
-Renal (urine Na+ > 20 mEq/L)
-Non renal (Urine Na+ <20 mEq/L(
Isovolemic Hypotonic Hyponatremia
TBW increase
Normal/slightly increased total body sodium
Most common cause of Isovolemic Hypotonic Hyponatremia
SIADH
SIADH
Syndrome of Inappropriate Anti Diuretic Hormone release
water intake exceeds capacity of the kidneys to excrete water*
-Urine Osm generally > 100 mOsm/kg
-Urine Na+ generally > 20-30mEq/L
SIADH primarily caused by
DRUGS
Antineoplastics
-Cyclophosphamide
-Vinicristine, viblastine
Antipsychotics
Bromocriptine
Carbamazepine
Chlorpropramide
Desmopressin
Meperidine, morphine
Nicotine
NSAIDs (ibuprofen)
Oxytocin
SSRis
-Fluoxetine
-Sertraline
TCAs
-Amitriptyline
Imipramine
Tolbutamide
Treatment of SIADH
Remove underlying cause (e.g. medications) if possible
First line - Free water restriction
HYPERvolemic Hypotonic Hyponatremia
Total body sodium increased but TBW increased MORE
EDEMA
-Cirrhosis
-Heart failure
-Kidney failure
-Nephrotic syndromes
Goal of treatment for hypovolemic
Restore volume deficit
DO NOT GIVE MORE THAN 8-12 mEq/L/day
Hypertonic NaCl (3%) if symptomatic (500 mEq)
Isotonic NaCl if asymptomatic
Goal of treatment for isovolemic
Furosemide and 3% NaCl if symptomatic
0.9% if Asymptomatic and water restriction
Goal of treatment for Hypervolemic
Furosemide and judicious 3% NaCl in symptomatic
Furosemide in asymptomatic patients
Acute symptomatic hyponatremia
BRAIN SWELLS
cerebral edema
Irreversible and sometimes fatal
Altered mental status and seizures
Treatment of Acute Symptomatic Hyponatremia
Increase serum sodium by 1-2 mEq/L/hr until symptoms resolve
-Goal 120 mEq/L
-Complete correction is NOT necessary - if correction is too rapid can cause demyelation
What is the max sodium increase to treat Acute Symptomatic Hyponatremia in the first day?
8-12 mEq/L in the first 24 hrs
Demyelination risk factors
Serum Sodium <105 mEq/L
Hypokalemia
Alcohol use disorder
Malnutrition
Advanced liver disease
Rule of 8
Treat with hypertonic saline (3%) - replace half of sodium deficit in 8 hrs; then remaining deficit within 8-16 hrs
Acute symptomatic hyponatremia monitoring
Serial exam of heart, lungs, and neurologic status several times over the first 12 hours
-Serum Sodium conc. q2-4 hrs until asymp
-then q 6-8hrs until WNL
Hypernatremia
Always associated with Hypertonicity
-Impaired thirst response or pts without access to water
-Infants
-Elderly
-Persons with a disability
Loss of hypotonic fluids OR ingestion of sodium or hypertonic fluids
Must assess volume status (ECF)
HyPOvolemic HyPERnatremia
Restore hemodynamic status first
-0.9 NACl
Once intravascular volume restored:
Calculate free water deficit
Replacing free water deficit
Provide free water
-D5W continuous infusion
-Enteral free water via feeding tube
Match I/O if possible
DO NOT CORRECT TOO QUICKLY
Goal is 0.5 mEq/l/hr decrease in Naserum
Isovolemic Hypernatremia (Diabetes Insipidus)
Etiology: brain injury/trauma, nephrogenic (drug induced)
TX:
-Desmopressin: Acute administer SubQ/IV 0.25-.5 mL BID
Chronic - Intranasally 0.05-0.2mL BID
Vasopressin: Acute continuous infusion titrated hourly to goal UOP
Potassium (K) levels
Normal Level: 3.5-5 mEq/L
HYPERvolemic HYPERnatremia
Hypernatremia from hypertonic fluids is uncommon
-Hypertonic saline resuscitation
TX:
-Stop hypertonic fluids/cause
-Rapidly excreted
-Diuretic if needed
Match I/O
Too much fluid - kick it out
Potassium use
Primary intracellular cation
Responsible for cell metabolism
Glycogen and protein synthesis
Determines the resting potential across cell membranes in cardiac and non-cardiac tissue
Hypo and hyper associated with fatal arrythmias
Factors affecting potassium
Na/K ATPase pump
-Insulin
-Glucagon
-Catecholamines
-Aldosterone
Kidneys
Arterial pH/acid-base returns
Hypokalemia - causes
Diuretic loss
B-agonist medications
NG drainage
Metabolic alkalosis
Diarrhea
Magnesium depletion
-Co-factor for Na/K ATPase
Which will kill a patient quicker hyper or hypokalemia
Hyperkalemia - do not want to overcorrect when treating: goal: normalize
Hyopkalemia treatment
3-3.4
Treatment debatable
PO K+ for patients with cardiac conditions
<3 mEq - ALWAYS treat
-PO route preferred
IV for symptomatic patients or pts who cannot take PO
Should attempt to correct Mg2+ deficit
IV K+
Do not give potassium push via IV - can kill someone
Arrhythmia or cardiac arrest if given too quickly
Infusion rate of IV K+ without cardiac monitoring
10 mEq/hr
Hyperkalemia
> 5.5 mEq/L
Cardiac arrythmias
Goals of therapy for hyperkalemia
C a big K drop
FIRST: Manage cardiac arrest
THEN:
1. Antagonize the membrane actions
2. Decrease the extracellular K+ concentrations
3. Remove K+ from body
C a Big K drop
- Antagonize the membranes (Calcium)
- A BIG
Decrease EC K+ concentrations
(Albuterol, Bicarb, Insulin and Glucose - push K+ back into cell where it belongs) - K DROP
-Remove K from the body
-Kayexalate/Lokelma
-Diuretics (furosemide)
-Renal unit of dialysis Of Patient
(3rd step not always necessarry)
Acute tx of hyperkalemia: need to know
Give calcium chloride whenever possible (one gram over 1-2 minutes)
DO NOT GIVE INSULIN WITHOUT DEXTROSE could have seizures
–Study chart in notes!!
Chronic tx of Hyperkalemia med
Patiromer (Valtassa)
MOA: Binds K+ in the GI tract and decreases absorption
Magnesium normal levels
1.5-2.5 mg/dL
Magnesium role in body
Important role in neuromuscular function
-Cofactor for ATP and Alkaline phosphatase
Related to Ca2+ and K+ metabolism
Regulated by intake and kidney excretion
Hypomagnesemia
<1.5 mg/dL
-Usually associated with disorders of the GI tract or kidneys
-Diarrhea
-Decreased intestinal absorption
-Severe malnutrition
Drugs
-Diuretics (thiazide or loop)
Goals of therapy for hypomagnesemia
-Resolution of symptoms
-Identify correct underlying causes
-Restoration of the NL MG2+ concentration
-Correction of concomitant electrolytes
Don’t forget to treat associated electrolyte disturbances
Tx of hypomagnesemia
PO
-Asymp with MG > 1
-Milk of mag (5-10 mL PO QID)
Mag-OX 800 mg PO daily or 400 mg PO TID w/meals
IV
-Symptomatic pts (or cannot tolerate PO)
Mg 1-2 mg/dL - 0.5 mEq/kg
Mg <1mg/dL 1 mEq/kg
Calcium Range in body
8.5-10.5 mg/dL
Calcium role in body
-Necessary for bone formation and neuromuscular function
-Serum concentrations are controlled mainly by the PTH, vitamin D, and calcitonin
-Organs involved in calcium metabolism: Bone, kidneys, and the intestine
Hypocalcemia
More frequently seen in hospitalized pts
Etiologies:
Mg deficiency
Large volumes of blood products
Hypoalbuminemia (must correct calcium)
Calcium correection
Measured calcium + (4-measured albumin) * 0.8)
Hypocalcemia Clinical presentation
Neuromuscular
-Muscle cramps, tetany
CNS
-Depression, anxiety, memory loss, confusion, hallucination, seizures
Dermatologic
-Hair loss, eczema
Cardiac
-QTC prolongation, arrythmias
Acute treatment hypocalcemia
100-300 mg elemental Ca IV over 5-10 min
1 gram CaCl = 3 grams Ca gluconate (270 mg elemental Ca)
Cl can be admin IV push during code
-Gluconate is preferred for PIV admin
(+) lower % of elemental Ca
(-) less predictable increase in Ca2+ concentration
(+) Less risk for extravasation (necrosis)
Usual admin rate - 1gm/hr
Correct hypomagnesemia
Chronic treatment hypocalcemia
PO Calcium
1-3 g/day of elemental Ca2+
-Vitamin D supplementation
-Calcitriol 0.25 mg PO daily or every other day
Phosphorous range in body
2.5-4.5 mg/dL
Phosphorous role
Critical for structure and function
-respiratory and cardiac muscle function
-Enzymatic rxns that control carbohydrate, fat, and protein metabolism
-Source of high energy bonds of ATP
-Modulates the oxygen carrying capacity of hemoglobin
-Regulated by intake, vitamin D, PTH and renal function
Makes ATP
Hypophosphatemia
Mild to moderate
1-2 mg/dL
Severe:
<1 mg/dL
Etiologies:
-Decreased intake
-Impaired absorption
-Intracellular shifts
4, 3, 2 rule
Keep K+ above - 4
Keep P above 3
Keep Mag above 2
Treatment of Hypophosphatemia - mild to moderate
Oral PO4
Phos-Nak -> 30-60 mMol/day in 2-3 doses (cannot handle all at once)
Fleets Phospho-soda (4.1 mMol/mL) 5 mL diluted 2-3 times/day
Treatment of Hypophosphatemia - severe
IV PO4
Use KPhos when K+ < 4mEq/L
Use NaPhos when K+ > 4mEq/L
Phos replacement
1 mMol NaPhos = 1.33 mEq Na+ & 1.33 mEq Phos
1mMol KPhos = 1.47 mEq K+ & 1.47 mEq Phos
Admin:
Give PO doses as divided doses
Infuse IV doses no faster than 7 mMol/hr
Never push KPHOS - only given as piggyback
