Unit one and Two Flashcards
Normal Sodium Levels
135-145 MEq/L
Critical values for sodium
less than 120 or greater than 160 mEq/L
Where is sodium normally found?
main cation of the ECF
How does sodium move in the body
active transport
What hormones influence sodium
aldosterone and antidiuretic hormone
what is the primary source of sodium
diet
What are the most dangerous problems with sodium imbalances
cerebral dehydration and seizure
Serum levels for Hyponaturemia
less than 135mEq/L
causes of Hyponatremia
vomiting Nasogastric suctioning diarrhea excessive diaphoresis wound drainage medication renal disease
Serum levels for hypernaturemia
greater than 146 mEq/L
Common cause of sodium gain
excessive sodium intake
inability to ingest water
hypertonic tube feeding w/o hypertonic IV fluids
Consequences of sodium retention
Hyperaldosteronism
Cushing’s syndrome
Corticosteroids
acute renal failure
Common assessment of sodium imbalances
confusion, coma, seizures, orthostatic hypotension, muscle weakness,
Common assessment findings of hyponatremia
headache, fatigue, apathy, respiratory distress, anorexia, weight loss, nausea, vomiting, abdominal cramps
Common assessment findings of hypernatremia
restlessness, irritability, lethargy, dyspnea, tachycardia, dry mucous membranes, dehydration, flushed skin, low urine output
How much of an adult body mass is water?
50-60% weight in adults
What affects water content
gender (greater in males), body mass( more fat, less water), age
How much water is in the ICF
2/3
what is interstitial fluid
fluid in spaces between cells
what is plasma
liquid part of blood
Transcellular fluid
small amount of fluid contained within specialized cavities of the body- CFS, GI tract, pleural
what are electrolytes
substances that when dissolved in water separate into charged particle
What are the cations in the body
sodium, potassium, calcium, magnesium
what are the anions of the body
chloride, phosphate, bicarbonate
What are the major functions of electrolytes
regulate water distribution, muscle contraction, nerve impulse transmission, blood clotting, regulate enzyme reactions, regulate acid-base balance
How does ICF and ECF transportation occurs
filtration diffusion facilitated diffusion osmosis active transport
Diffusion
passive movement of particles across a permeable membrane from a higher concentration to a lower concentration
Example of diffusion
gas exchange in the alveoli
Facilitated Diffusion
movement of specific particles across a cell membrane by a protein carrier
passive
Examples of facilitated diffusion
glucose and amino acids entering or leaving the cell
Active Transport
movement of particles across a cell membrane from areas of low concentration to areas of higher concentration by combining with a carrier on the outside of the cell membrane and moving the inside of cells
requires energy
Example of active transport
sodium/potassium pump
Normal potassium values
3.5-5.0 mEq/L
critical value of potassium
2.5-6.5 mEq/L
Role of potassium
significant role in cardiac muscle, skeletal muscle and smooth muscle activity
How does potassium move
active transport with sodium-potassium pump
What hormone enhances kidney excretion of potassium
aldoserone
what is the primary source of potassium
diet
causes of Hypokalemia (less than 3.5)
vomiting prolonged gasrtic suctioning chronic diarrhea eating disorders hemorrhage medication
causes of hyperkalemia (greater than 5.5)
acute renal failure chronic kidney disease glomerulonephritis addison's disease medication excessive of potassium intake
What is calcium
the most abundant mineral in human body
where is calcium found
99% in bones and teeth
1% in blood stream in bound form and ionized form
What is ionized calcium
is the active form of calcium and must be maintained in a narrow range
what is calcium bound to
serum proteins, especially albumin
where does calcium get absorped
in the intestines and requires active form of vitamin D
What is calcium required for
transmission of nerve impulses, cardiac muscle contractility
clotting mechanism
teeth and bone formation
Hypocalcemia serum levels
total- < 8.5mg/dl
ionized- < 4.9 mg/dl
what causes hypocalcemia
any condition that decreases the production of parathyroid hormone surgical removal or injury pancretitis multiple blood transfusion laxative abuse
what happens when serum calcium levels is low?
calcium is borrowed from the bones
Why can pancreatitis cause hypocalcemia
lipolysis produces fatty acid that combine with calcium ions decreasing serum calcium levels
Why does multiple blood transfusions cause hypocalcemia
the citrate use to anticoaguleate blood binds with the calcium
Consequence of hypocalcemia
increased nerve excitability and sustained muscle contraction- tetany
- due to decreased calcium level, decreases threshold levels
Consequence of Hypocalcemia
Chvostek Trousseau Laryngeal strigor Dysphagia numbness and tingling around mouth
Chvostek sign
twitching of the lip and muscles on the side of the face stimulated from a tap over the facial nerve in front of the ear
(cranial nerve VII)
Trousseas sign
carpel spasms produced by inflating a blood pressure cuff on the arm
Treatment of hypocalcemia
oral/ IV replacement (calcium gluconate or calcium chloride)
Vitamin D
Aluminum hydroxide gel- hyperphosphatemia
Mg for Hypomagnesemia
Hypercalcemia serum levels
> 10.5 mg/dL- total
> 5.0 mg/dL - ionized
Critical calcium values
12 mg/dL
Causes of hypercalcemia
excess intake loss from bones, increased mobilization from bones steroid therapy hyperthyroid Metastatic Cancer
Treatment of hypercalcemia
volume expansion with NS
loop diuretics or corticosteroids
calcitonin and/or mithramycin (prevent bone reabsorption
Phosphorus serum levels
2.5-4.5 mg/dL
what does phosphorus assist with
muscle contraction, maintaining heart rhythm, kidney function, nerve conduction, acid-base balance, functioning of RBC
metabolism of protein, fat and carbs
Phosphorus is a major component of what
ATP, DNA, RNA
where is most of the phosphorus found
85% bound to teeth and bones
rest in cells
what regulates phosphorus
parathyroid hormone
What are phosphorus levels related to
glucose intake, insulin administration, hyperventalation
Hypophosphatemia serum levels
< 2.4mg/dL
causes of hypophosphatemia
malabsorption syndrome recovery from malnutrition or refeeding syndrome glucose or insulin therapy TPN alcohol withdraw phosphate-binding antacids respiratory alkalosis
serum levels of hyperphosphatemia
level greater than 4.4 mg/dL
causes of hyperphosphatemia
chemotherapy for leukemia or lymphoma excessive milk injetion excessive use of phosphate containing laxative or enemas vitamin D excess chronic kidney disease acute renal failure hypoparathyroidism sickle cell anemia
Normal magnesium serum levels
1.6-2.6 mg/dL
what is the major role of magnesium
major role in 300 fundamental enzymatic reactions powers the sodium-potassium pump aids converting ATP to ADP transmits electrical impulses important in skeletal muscle relaxation maintains heart rate Necessary for release of PTH
Hypomagnesemia serum level
1.5 mEq/L
Hypomagnesemia causes
nutritional or metabolic abnormalities
fluid loss form GI tract
redistribution of body magnesium
What inhibits magnesium absorption
phytates
oxalates
fat
Assessment findings of hypomagnesemia
similar to hypocalcemia or hypokalemia muscle twitching tremors hyperreactive reflexes mood changes nausea, vomiting, diarrhea seizures, hallucinations
What is SIADH
syndrome of inappropriate antidiuretic hormone
results in water intoxication and hyponatremia
characteristics of SIADH
fluid retention serum hypoosmolality dilutional hyponatremia hypochloremia concentrated urine common in elderly
causes of SIADH
Malignant tumor
central nervous system disorders
drug therapy
miscellaneous condition
Signs and Symptoms of SIADH
clinical signs and symptoms related to hypovolemia dn hyponatremia are present as mild to severe low urine output dark concentrated urine thirst dulled sensorium dyspnea hypertension
Osmosis
a process by which molecules of solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane
Osmolality
concentration of solute per kilogram of water
Osmolarity
concentration of solutes per liter of solution
Serum osmolality
measures the body’s water balance
Normal values of osmolality
275-295 mOsm/Kg
Water deficit osmolality
value higher than 295 mOsm/kg- concentration of particles is too great or the water is too low
Water excess osmolality
values lower than 275 mOsm/kg- too little solute for the amount of water or too much water for the amount of solute
Conditions that increase serum osmolality-
dehydration/sepsis/fever/ sweating burns
Diabetes mellitus
Diabetes Insipidus
Uremia
Hypernatremia
Ethanol, methonal or ethylene glycol ingestion
mannitol therapy
Conditions that increase urine osmolaity
dehydration SIADH adrenal insufficiency glycosuria Hypernatremia High protein diet
Conditions that decrease serum osmolality
excess hydration
hyponatremia
SIADH
Conditions that decrease urine osmolality
diabetes insipidus
Excess fluid intake
acute renal insufficiency
glomerulonephritus
Tonicity
refers to the osmolality of a solution
Isotonic solution
fluids with the same osmolality of the cell interior. Remains in the vascular compartment
expanding vascular volume
Normal Saline 0.9%
Hypertonic Solutions
fluids with solutes more concentrated than in the cell (increased osmolality)
causes a shift from cells into the vascular space, expanding vascular volume
- 3% Normal Saline
Hypotonic Solution
solutes are less concentrated than in the cell. Helps to move cellular dehydration through shifting out of blood vessels into the cells promotes elimination by kidneys
0.45% normal saline
Oncotic Pressure
Pressure caused by plasma colloids in a solution
protein is the major colloid in the vascular system
plasma proteins attract water pulls from tissue to vascular space
What is the capillary fluid movement determined by?
Capillary Hydrostatic Pressure
Plasma Oncotic pressure
Interstitial hydrostatic pressure
Interstitial oncotic pressure
Which pressures move water out of the capillaries
capillary hydrostatic pressure and interstitial oncotic pressure
Which pressures moves fluid into the capillaries
Plasma oncotic pressure and interstitial hydrostatic pressure
Distribution of water
First spacing
normal distribution in ICF and ECF
Distribution of water
Second Spacing
Abnormal accumulation of interstitial fluid
Distribution of Water
Third Spacing
accumulation of fluid in a part of the body where it cannot be use- fluid is trapped
what controls the body’s water balance
Needs access to water
Normal thirst and ADH mechanism
Normal functioning kidneys
What is the primary protection of hyperosmolality
the thirst mechanism
How is the thirst mechanism stimulated
Stimulated by fluid loses or increases by thirst receptors in the hypothalamus
stimulates ADH and aldosterone release
Where are glucocorticoids and mineralcorticoids secreted?
by the adrenal cortex
What is the function of glucocorticoids and mineralcorticoids
regulate water and electrolytes
function of glucocorticoids (cortisol)
anti-inflammatory effect and increase serum glucose levels
response to physical stress
Function of Mineralcorticoidis (aldosterone)
enhance sodium retention and potassium excretion
What triggers aldosterone release?
drop in blood pressure or blood volume
action of aldosterone
causes kidneys to reabsorb more sodium into the blood increasing serum sodium levels- water follows
- lowers serum potassium levels
Atrial Natriurtic Peptide (ANP)
Characteristic
Cardiac Hormone found in the atria
released by high blood volume and high blood pressure
How does ANP lower blood pressure
causes vasodilation and suppressing the RAAS
decreases ADH
Increases GFR
Brain Natriuretic Peptide characteristics
cardiac hormone, within the ventricles released with increased blood volume and pressure when ventricles are stretched
How do BNP decrease blood volume and pressure
vasodilation of Arteries and veins
Decrease release of aldosterone
Diuresis- resulting in excretion of both sodium and water
What causes fluid deficit?
diarrhea fistula drainage hemorrhage Polyuria inadequate intake
What is the goal of treatment for fluid volume deficit
correct cause
replace water and electrolytes
IV fluids 0.9 NS or LR
Blood
How is SIADH diagnosed
low urine output
high specific gravity
sudden weight gain without edema
decreased serum sodium level
What is the treatment of SIADH
Treatment of underlying cause
Fluid restriction
gradual weight loss
progressive rise in serum sodium concentration and osmolality, symptom improvement
head of bed flat or no more than 10 degrees- enhance venous return
What results in an over production of ADH
Syndrome of inappropriate antidiuretic hormone
what results in an underproduction of ADH
diabetes insipidus
What is the osmolarity of patients with SIADH
lows osmolarity
What are the characteristics of SIADH
fluid retention, serum hypoosmolality, dilutional hyponatremia, hypochloremia, concentrated urine in the presence of normal or increased intravascular volume and normal renal function
what population is SIADH more common?
older adults
what are the Causes of SIADH
malignant tumors, drug therapy, CNS disorders, hypothyroidism, lung infection, COPD
what are the affects of ADH
increase the permeability of renal distal tubule and collecting duct- leads to reabsorption of water , ECF volume increases, GFR increases, sodium levels decline
how is the diagnosis of SIADH made
by the simultaneous measurements of urine and serum osmolality
what should a nurse look for in patients at risk for SIADH?
low urine output with high specific gravity
sudden weight gain without edema
decreased serum sodium levels
Monitor I&O, vital signs, heart and lung sounds
signs of hyponatremia
What is the treatment of SIADH
- avoid medications that stimulate ADH release
fluid restriction
position the head of bed flat or elevated 10 degrees
why would you position the bed of a patient with SIADH at 10 degrees or flat?
because it enhances venous return to the heart and increase left atrial filling pressure, thereby reducing the release of ADH
what is the fluid restriction of a patient with chronic SIADH
800-100 mL of water daily
What medication is often given to patients with chronic SIADH
Demeclocycline
what are the actions of demeclocycline
blocks the effects of ADH on the renal tubules resulting in more dilute urine
What causes diabetes insipidus(DI)?
caused by a deficiency of production or secretion of ADH or decreased response to ADH
what is the most common cause of DI?
central DI
What is the etiology of central DI
results from an interference with ADH synthesis, transport or release
-brain tumor, head injury
what is the etiology of nephrogenic DI
results from inadequate renal response to ADH despite presence of adequate ADH
primary DI
results from excessive water intake
what are the clinical manifestation of DI
polyuria and polydipsia
what are the phases of onset for central DI
acute phase- polyuria
interphase- urine volume normalize
third phase- central DI is permanent- 10-14 days after surgery
what is the nursing management of DI
early detection
maintenance of adequate hydration
patient teaching
what is the treatment of central DI
fluid and hormone therapy
- IV hypotonic saline or dextrose 5%
What is the treatment of nephrogentic DI
dietary measures and thiazide diuretics, and in some cases taking indomethacin (NSIAD that increases sensitivity to ADH)
When does hypovolemic shock occur?
after a loss of intravascular fluid volume
what is absolute hypovolemia
results when fluid is lost through hemorrhage, gastrointestinal loss, fistula drainage, diabetes insipidus, or diuresis
what is relative hypovolemia
fluid volume moves out of the vascular space into extravascular space (third spacing) burns.
what is a consequence of decreased intravascular volume
decreased venous return decreased preload decreased stroke volume decreased CO decreased tissue perfusion and impaired cellular metabolism
What is the clinical presentation of hypovolemic shock?
tachypnea -> bradypnea decreased urine output pallor, cool clammy skin Decreased cerebral perfusion (anxiety, confusion, agitation) Absent bowel sounds
Diagnostic lab findings of hypovolemic shock
hematocrit hemoglobin lactate urine specific gravity changes in electrolytes
How much fluid may a patient compensate for?
up to 15% of total blood volume
A loss of 15-30% of total blood loss results in what?
sympathetic nervous system mediated response
What happens in a sympathetic nervous system mediated response?
increased HR
Increased CO
Increased respiratory rate and depth
The stroke volume, central venous pressure is decreased
How is hypovolemia corrected?
by crystalloid fluid replacement
