Fluid and Electrolytes Flashcards
What are the 4 processes that move water and electrolytes between body compartments, maintaining equal osmolality?
- Active transport
- Passive diffusion
- Osmosis
- Filtration
What is active transport?
Cells maintain their high IC electrolyte concentration by active transport.
Active transport requires energy in adenosine triphosphate (ATP) to move electrolytes across cell membranes against the concentration gradient (from areas of lower concentration to areas of higher concentration). Ex: Na+- K+ pump, moves Na+ out of cell & K+ into cell and keeping ICF low Na+ and high K+
What is passive diffusion?
Passive movement of electrolytes or other particles down a concentration gradient (from areas of higher concentration to areas of lower concentration).
What is osmosis?
Movement of water across a partially permeable membrane from a region of high concentration to an area of low concentration.
What is filtration?
Filtration is when fluid moves into and out of capillaries (between the vascular and interstitial compartments).
CV causes of extracellular fluid volume deficit
blood/plasma loss, hemorrhage, burns
GI reasons for extracellular fluid volume deficit
vomiting, laxative overuse, drainage from fistulas or tubes, diarrhea
(Increased) renal output reasons for extracellular fluid volume deficit
diuretics, adrenal insufficiency (deficit of cortisol & aldosterone)
Physiological Effects of Extracellular Fluid Volume Deficit
FAST FLUDDS.
This stands for:
F - Flat neck veins
A - Sudden weight loss (overnight)
S - Slow vein filling
T - Tachycardia
F - Postural hypotension
L - Thready pulse
U - Dry mucous membranes
D - Dark yellow urine
S - Poor skin turgor when supine
Severe PE of Extracellular Fluid Volume Deficit
CRITICAL DASH.
This stands for:
C - Confusion
R - Restlessness
I - Hypotension
T - Thirst
I - oligUria (UO < 30 mL/hr)
C - Cold, clammy skin
A - Decreased LOC
L - Hypovolemic shock
D - Hypotension
A - Thirst
S - Restlessness
H - Hypovolemic shock
What are labs to monitor for fluid volume deficit?
↑Hct
↑BUN > 20 mg/dL (7.1 mmol/L) (hemoconcentration)
urine specific gravity > 1.030, unless renal cause
In patients with extracellular fluid volume deficit, Na+ & H2O intake is ______ than output, leading to isotonic _________.
less; loss
In patients with extracellular fluid excess, Na+ & H2O intake is __________ than output, leading to isotonic _____.
greater, gain.
Renal retention of Na+ and H2O can lead to? (4)
- heart failure
- cirrhosis
- aldosterone or glucocorticoid excess
- acute or chronic oliguric renal disease
PE of fluid volume excess
Sudden weight gain (overnight), edema (especially in dependent areas), full neck veins when upright or semi-upright, crackles in lungs
Severe PE of fluid volume excess
Confusion and pulmonary edema
What labs to monitor for fluid volume excess?
↓Hct, ↓ BUN < 10 mg/dL (3.6 mmol/L) (hemodilution)
What is hyponatremia?
H2O excess; water intoxication; hypoosmolar imbalance) – body fluids too dilute
What are some causes of hyponatremia?
increased ADH, pyschogenic polydipsia or forced excessive water intake, use of hypotonic irrigating solutions, and tap-water enemas.
Signs and symptoms of hyponatremia
↓ LOC (confusion, lethargy, coma), seizures if develops rapidly or is very severe
Labs for hyponatremia
Na+ < 136 mEq/L
Serum osmolality < 285 mOsm/kg.
What is hypernatremia?
Water deficit; hyperosmolar Imbalance) – concentrated body.
What are some reasons someone might gain more salt than water (hypernatremia)?
salt tablets, tube feedings, hypertonic parenteral fluids
Lack of access to water, deliberate water deprivation, inability to respond to thirst (e.g., immobility, aphasia)
Dysfunction of osmoreceptor-driven thirst drive
What are some reasons someone might lose more water than salt? (hypernatremia)
diabetes insipidus (ADH deficiency)
osmotic diuresis
large insensible perspiration & respiratory water output without ↑water intake
