Fluid and Electrolyte balances Flashcards
What is the goal of fluid & electrolyte balance?
To maintain homeostasis
What is the nursing role when dealing with fluid & electrolyte imbalances?
anticipate potential for alterations
recognizing the S&S of imbalances with appropriate action
Composition of fluids in the body
intracellular fluid (2/3) Extracellular fluid (1/3)
Sodium
135-145 mEq/L
- essential for muscle contractions, transmission of nerve impulses and acid-base balance
- kidneys regulate and it is influenced by ADH & aldosterone
Potassium
- 5-5.0 mEq/L
- essential for skeletal, cardiac, muscle contraction; maintains acid-base balance
Chloride
98-106 mEq/L
Bicarbonate
24-31 mEq/L
Calcium
- 5-10.5 mg/dL
- Role in transmitting nerve impulses, regulates muscle contraction & relaxation that includes cardiac
- Activates enzyme, role in coagulation
- Vitamin D needed for absorption from the GI track
Phosphate
- 5-4.5 mg/dL
- essential to the function of muscle, RBCs, & the nervous system
- Deposited with calcium for bone & tooth structure
Magnesium
- 8-3.0 mg/dL
- Role in carbohydrate & protein metabolism
- Regulated by GI absorption & renal excretion
- Important for normal cardiac function
Hydrostatic pressure
pressure exerted by the fluid on the walls of the blood vessels by the heart
pressure within the arterial end of the capillary pushes water into the interstitial space
Oncotic pressure
exerted primarily by albumin
osmotic force of plasma proteins draws fluid back into the capillary at the venous end
Osmosis
fluid shifts through membranes from low solute concentration to high solute concentration
Diffusion
solutes moves from area of higher concentration to a lower concentration
Filtration
passage through a filter that prevents passage of certain molecules
Active transport
sodium moves out of the cell & potassium moves into the cell to maintain concentration
Kidneys
regulate by adjusting urine volume
- filter plasma
- Excrete urine
- Regulates: ECF volume, electrolyte levels in ECF, pH of ECF, excretion of metabolic wastes & toxic substances
Skin (sensible perspiration) & Lungs (insensible loss)
- invisible vaporization from lungs & skin assists in regulating body temperature
- Excessive sweating (sensible perspiration) from fever or high environmental temperatures
GI
- water intake, food metabolism, solid foods
- GI tract secretes & reabsorbs
- In healthy people, daily average intake & output of water are approximately equal
Renin-Angiotensin-Aldosterone System
-Renin released in response to decreased blood flow (decrease CO) or decreased renal pressure (sensed by receptors in the nephrons)
Antidiuretic Hormone (vasopressin)
a fluid deficit or increase in plasma osmolality is sensed by osmoreceptors in the hypothalamus which in turn stimulate thirst & ADH release
Heart
rate, conduction, contractility & blood vessel resistance affects blood circulation to the kidney affecting renal perfusion
what is released in response to increased fluid volume (HF) & high serum sodium levels?
ANP- a hormone secreted by cells in the lining of the atria
BNP- a hormone secreted by cells in the lining of the ventricles
Lungs
approximately 400 mL water removed daily through exhalation
Parathyroid
- regulates calcium & phosphate
- PTH regulates movement of calcium out of bone to the blood, calcium absorption from intestines, and calcium reabsorption from the renal tubules
Osmolality
measures the solute concentration per kilogram in blood & urine
Osmolarity
also describes the concentration of solutions measured in milliosmoles per liter
Urine Specific Gravity
(1.010-1.025)
SG varies inversely with urine volume
-increase SG= concentrated urine (FVD)
-decrease SG= dilute urine (FVE)
BUN
10-20 mg/dL
-end product of the metabolism of protein from muscle & diet by the liver
“PROTEIN ON A BUN”
Creatinine
- 7-1.4 mg/dL
- end product of muscle metabolism
Isotonic Fluid
solutions with the same osmolality as the cell interior; about equal to serum; stays in the intravascular space after administration
USE: replace ECF losses, expand the intravascular volume
Example: NS (0.9%), LR, 5% dextrose in water (DSW)
Hypotonic Fluid
solutions in which the solutes are less concentrated than the cells
USE: expands the intracellular space, rehydrates the cells, treats gastric fluid loss & dehydration
Example: 0.33% NaCl, 0.45% NaCl
Hypertonic Fluid
solutions more concentrated than cells
USE: draws fluid out of cells to restore circulating volume, decreases cellular swelling, treats severe hyponatremia
Example: 3% NaCl, 5% NaCl, D10%W
Gerontologic Considerations
structural changes in the kidney: decrease in GFR & creatinine clearance, inability to concentrate urine, & inability to conserve water & electrolytes
- hormone changes
- loss of SC tissue & dermis
- Decreased thirst mechanism
- Musculoskeletal barriers
- Mental status changes
- medications
FVD
(Hypovolemia) water & electrolyte are lost in equal proportion
-loss of body fluids or inadequate fluid intake
Who are susceptible to having FVD?
elderly and very young children because of the inability to care for themselves properly
Dehydration
loss of pure water alone without corresponding loss of sodium
Management of FVD
- encourage oral fluids
- isotonic or Hypotonic IV fluids
- Blood replacement if needed
- Complication: hypovolemic shock
Nursing role with FVD
monitor S&S of cerebral edema & pulmonary edema, IV site, VS, lab, daily weight
FVE
(Hypervolemia) is an excess of isotonic fluid (water & sodium) in the extracellular (interstitial or intravascular compartment.
Management of FVE
- identify primary cause & treat
- Hypertonic solutions followed by diuretics
- Fluid & sodium restrictions
- Hemodialysis
Nursing role with FVE
fluid and dietary restrictions, O2 therapy, assess S&S of hypovolemia, monitor O2 sat, ABGs, VS, monitor potassium level, heart & lung sounds, daily weight
Vital signs FVD vs FVE
FVD- hyperthermia, tachycardia, hypotension, orthostatic hypotension and an increase H&H
FVE- bounding pulse, increased BP, SOA, increased respiratory rate and a decreased H&H
Neuromuscular FVD vs FVE
FVD- dizziness, syncope, confusion, weak, fatigue, muscle cramps and increased BUN & creatinine
FVE- confusion, headache, seizures, coma and decreased serum osmolarity and sodium
Respiratory FVE
cough, dyspnea, crackles, pulmonary edema, distended jugular veins and decreased urine sodium & specific gravity
GI FVD`
thirst, dry furrowed tongue, weight loss and increased urine specific gravity & osmolarity
Renal FVD
oliguria, concentrated urine and increased serum sodium, osmolality, & specific gravity
Water intoxication
occurs when excess fluid moves from the extracellular space to the intracellular space
What can cause water intoxication?
- SIADH
- Rapid infusion of a hypotonic solution
- Excessive use of tap water as an NGT irrigant or enema
- Pyschogenic polydipsia
What are symptoms of water intoxication?
- increased ICP
- change in LOC
- Muscle cramps & weakness
- Headache
What are the major electrolytes in ECF?
sodium and chloride
what are the most plentiful intracellular electrolytes?
potassium, phosphate, and magnesium
