Fluid & Electrolytes (Part 2) Flashcards
Fluid Management Goal
Euvolemia
Maintain adequate:
Intravascular fluid volume
LV filling pressure
CO
SBP
Oxygen delivery to tissues
Physical Exam
Skin turgor
Mucus membranes
Peripheral pulses
Resting heart rate and blood pressure
Orthostatic changes
Urine output
NPO Status
Body Fluid Composition
approx. 55-60% water
2/3 Intracellular
1/3 Extracellular
(Functional Compartments)
ICF
-body weight
-ions
ICF: 40% of your weight
~ 28 L (2/3 of body H20)
Primary Ions:
K+, Mg+2, PO4-2 & proteins
controls constituents of ICF
Cell membranes & cellular metabolism
Extracellular fluid
-body weight
-ions
The remaining 1/3 of body water
approx. 20% of body weight
Primarily a Na+, Cl- & NaHCO3 solution
Interstitial Fluid (ISF)
surrounds cells
does not circulate
~ 80% of the ECF
Plasma
ECF component of blood
~20% of ECF
ECF is 80% ____ & 20% ___.
80% interstit.
20% plasma
Examples of extracellular fluid
Interstitial Fluid (ISF) (80%)
Plasma (20%)
Transcellular fluid
Transcellular fluid
are fluids that are outside of the normal compartments
Transcellular fluids
examples
how many Liters?
CSF, digestive (gastric) juices, mucus, etc.
1 - 2 liters of fluid
TBW
values for M, F , infants & obese
Total body water (TBW) varies with age, gender & body type
Males: 60%
Females: 50%
Infants: 80%
Obese adults & diabetics: less water per kg
Basic constituent of the human body
water
Laboratory Evaluation
Hypovolemia
Increasing Hct
Hypernatremia
Metabolic acidosis (severe hypovolemia)
Urine SG >1.010
Urine Na < 10 mEq/L
Urine osmolality > 450 mOsm/kg
BUN: creatinine ratio > 10:1
Urine specific gravity assessment
Signs of Hypovolemia
5%
10%
15-20%
⭐️
Hypovolemia
A drop in BP does not occur in a patient that is already in the supine position until about __% of the blood volume is lost
30
Intraop Urine output goals
0.5-1 ml/kg/hr
BURN pts:
1.5 ml/kg/hr
Decrease in urine output generally does not occur until ___% of blood volume is lost
~20
Signs of Hypervolemia
Pitting edema
Presacral edema
Later signs:
Tachycardia
Crackles
Wheezing
Pulmonary edema
T/F
Chest X-ray is not a reliable assessment tool for hypervolemia.
False
Electrolytes
ECF & ICF
ECF:
Major (+): Na, K, Ca
Major (-): Cl, Bicarb, Proteins
ICF:
Major (+): Na, K, Mag
Major (-): Cl, Bicarb, Proteins
*same major anions
*difference is in major cations
“this is Ma Mag”
“Kick out Ca”
Most important electrolytes
Sodium, Potassium, and Calcium
affects resting membrane potential
K
determines threshold potential
Ca
Na fxn
resting potential
generate & propagate AP
Which ions affect excitability of nerve & muscle?
Sodium, Potassium, and Calcium
He didn’t emphasize this chart much
Hypernatremia
cause
at risk population
Secondary to lack of water
At risk:
Debilitated and dehydrated
Extremes of age
Altered LOC
T/F
Hypernatremia is often d/t excessive sodium intake
False
Secondary to lack of water – not because of too much salt
HyperNa
S/S
S/S:
Restlessness, lethargy, seizures and death
-reflect rate of H20 movement from brain
-Ruptured cerebral veins, focal hemorrhage
(Coma = HypoNa)
Na NR
135 - 145 mEq/L
Most common cause of diabetes insipidus
Hypernatremia w/ normal total body sodium
results from medical intervention
diabetes insipidus
w/ normal total body sodium
↓↓↓ renal “concentrating-ability”
↓ ADH secretion
renal tubules don’t respond normally to circulating ADH (polyuria)
polyuria
excessive pale urine
⭐️
HyperNa w/ low total body Na
Lost sodium & water
Water loss > sodium loss
Losses:
renal (osmotic diuresis)
or
extrarenal (diarrhea or sweat)
⭐️
HyperNa w/ increased total body sodium
Most commonly caused by the administration of large quantities of hypertonic Na+ solutions (3% NaCl or 7.5% NaHCO3)
Cushing’s syndrome – too much ACTH
hypertonic Na+ solutions
3% NaCl or 7.5% NaHCO3
⭐️
Most commonly caused by the administration of large quantities of hypertonic Na+ solutions
HyperNa w/ increased total body Na
Cushing’s syndrome = too much ___
ACTH
Hypernatremia > 145 mEq/L
S/S
Neuro:
Extreme Thirst
Progressive Weakness & Fatigue
Intracranial bleeding (brain shrinks→vessels pull/shear)
Disorientation, Hallucination, Irritability
CV:
Hypovolemia
Renal:
Oliguria
Renal Insufficiency
⭐️
Treatment of Hypernatremia
how fast can we correct it?
fluid deficits corrected over 48 - 72 hours:
hypotonic solution (D5W)
MAX Na decrease: 0.5 - mEq/L/hour
Rapid fluid deficit correction can result in
seizure, cerebral edema and coma
Elective surgery should be postponed until sodium level is ___ mEq/L and H2O deficits corrected
< 150
Hyponatremia
Associated conditions/diagnosis
alcoholism
liver failure
severe burns
malignant neoplasms
hemodialysis and sepsis