Fluids and Electrolytes Flashcards
Nursing Care Key Highlights for Fluid & Electrolyte Imbalance
The nurse must anticipate potential alterations of fluid and electrolytes
Check labs and trends
Vital signs
I & O, weight
Auscultate lung sounds, heart sounds, assess for edema.
Assess heart rhythm
Ask the patient if they are experiencing any problems with breathing, chest pain, etc
Blood is composed of:
Hgb and Plasma (water)
Hgb and Plasma = 100% of blood
40% Hgb + 60% Plasma = blood
If plasma decreases (dehydration), Hgb increases.
If plasma increases (fluid overload), Hgb decreases.
Calculation of Fluid Gain/Loss: 1 L of water = \_\_\_ 240 mL (8 oz) = \_\_
A patient receiving diuretics loses 4.4 lb (2 kg). How much fluid has he lost?
1 L of water = 2.2lb (1 kg) 240 ml (8 oz) = 0.5 lb (0.24 kg)
ANS: approx 2L
Weight losses of more than 1-2 lb per day is usually due to ___.
water loss
osmolality
measures the number of milli-osmoles per kilogram of water or the concentration of molecules per weight of water - Plasma, urine and other body fluids
Normal plasma osmolality is between 275 and 295 mOsm/kg.
> 295 = too much solute or too little water
< 275 = too little solute or too much water
Isotonic: The same osmolality as the cell interior (0.9% NS, LR)
stays in intravascular space & hydrate cells (if dehydrated)
Hypotonic (hypoosmolar): Solutions in which the solutes are less concentrated than the cells (D5W, 0.45% NS)
fluid into cells
Hypertonic (hyperosmolar): Solutions in which the solutes are more concentrated than the cells (3% Normal Saline, D5 ½ Normal saline, D5NS, D10W)
fluid out of cells
hydrostatic pressure
PUSH pressure
blood pressure generated by the contraction of the heart.
Allows for fluid entry at the beginning of the capillary and exit at the end of the capillary
oncotic pressure (colloidal osmotic pressure)
PULL pressure
The pressure exerted by solids. Ex. Proteins, Glucose
Water follows these large molecules
Albumin* - that’s why we give albumin with edema, it attracts the water
Diuresis with DKA*
ADH/Vasopressin release
The method by which the pituitary regulates water balance.
most important role is to conserve the fluid volume of your body by reducing the amount of water passed out in the urine
ADH released when:
- SIADH caused by brain tumors, brain injury, small cell lung cancer (mets) water retention
- Diabetes Insipidus (suppressed ADH)
- Stimulates ACTH to help stimulate aldosterone secretion in adrenals
The adrenal cortex regulates water balance via:
Glucocorticoids (Cortisol)
a. Anti-inflammatories
b. Increase serum glucose
Mineralocorticoids (aldosterone)
a. Enhance Na+ retention (and thus water retention)
b. Enhance K+ excretion
Cardiac regulation of water balance:
Natriuretic peptides (ANP & BNP) response to increased pressures and promote excretion of sodium and water
GI regulation of water balance:
- Normal water intake and output are normally between 2L & 3L per day
- GI tract secretes about 8L of digestive fluids each day
- Most reabsorbed
- Diarrhea or vomiting can lead to serious fluid loss
Renal regulation of water balance:
Kidneys reabsorb 99% filtrate, produce around 1.5 L of urine a day
Gerontologic considerations for water balance are:
i. Renal blood flow and function may be impaired or lessened
ii. Decreased Renin and aldosterone
iii. Increases in ADH and ANP
iv. Loss of subcutaneous tissue and dermis increased loss of moisture
v. Decreased thirst
vi. Musculoskeletal changes
vii. Mental status changes
viii. Incontinence
Fluid spacing
First spacing:
- Normal distribution of fluid in the ICF and ECF
- all fluid that is where it is supposed to be, including fluid inside cells and inside the blood vessels
Second spacing:
- abnormal accumulation of fluid of interstitial spaces (edema-varicose veins, pulmonary edema)
- This fluid is NOT in the cells, and NOT in the blood vessels
Third spacing:
- Trapping of water in areas that are non-functional and difficult to move back into cells or blood vessels (ascites, surgical shifts, burns, trauma, sepsis)
- Term often interchanged with edema
Fluid shifts
Shifts from plasma to interstitial fluid (Edema)
Caused by
- Increased Plasma hydrostatic pressure
- Decreased Plasma oncotic pressure
- Decreased interstitial hydrostatic pressure (lymph blockage)
