Fluid And Electrolytes Flashcards
What is the best indicator of fluid volume balance?
Daily weight.
How many calories makes 1 pound?
3500 calories
What are the two major fluid compartments?
Intercellular and Extracellular
What fraction of total body water does I intracellular fluid make up?
2/3 of body water
What fraction of total body water does extracellular fluid make up?
1/3 of body water
Where is intracellular fluid found?
Inside the cells
Where is extracellular fluid found?
Outside the cells
What are three types of extracellular fluid?
Plasma, Interstitial, and Transcellular
Where is interstitial fluid found?
Around the cells in the tissues.
Where is transcellular fluid found?Provide 3 examples.
In the organs. E.g. Cerebral spinal fluid, intraocular fluid, peritoneal fluid.
Which type of fluid is not taken into consideration when calculating input and output?
Transcellular fluid
What three main components of body fluids exert pressure?
Sodium, Albumin, Glucose
What is isotonic tonicity?
When fluid and electrolytes are appropriately balanced.
What is hypertonic tonicity?
Too many particles in the body fluids.
What is hypotonic tonicity?
Not enough particles in body fluids.
What type of fluid does tonicity refer to?
Extracellular fluid
What happens when extracellular fluids are hypertonic?
Fluid is pulled out of the cells resulting in dehydration.
What happens when extracellular fluid is hypotonic?
Fluid is pulled into the cells resulting in edema.
What is the simplest mechanism for maintaining fluid balance and where does it originate?
Thirst, the hypothalamus
The hypothalamus signals the pituitary to produce what hormone and why?
Antidiuretic Hormone (aka ADH, aka Vasopressin). When the hypothalamus senses low blood volume and increased serum osmolality, it signals the pituitary gland.
Why affect does ADH have?
It causes the kidneys to retain water resulting in increased blood volume and decreased serum osmolality.
What system do the kidneys use to keep fluid volume balance?
Renin-Angiotensin-Aldosterone System
When is renin produced in the kidneys?
When blood flow to the glomerulus drops, juxtaglomerular cells secrete renin into the blood stream.
What does Renin do?
Converts angiotensinogen to angiotensin 1.
What happens to angiotensin 1 after being converted?
Travels to the lungs where it is converted to angiotensin II via angiotensin converting enzyme (ACE).
What 2 effects does angiotensin II have?
- Causes vasoconstriction (which raises blood pressure)
2. Travels to the adrenal glands to stimulate aldosterone.
What effect does Aldosterone have?
- Increases resorption of sodium and water with the nephrons of the kidneys.
This leads to retention of water which increases fluid volume and blood pressure.
What is the function of hypertension medications called ACE inhibitors?
Prevents Angiotensin converting enzyme (ACE) from converting angiotensin I to angiotensin II. This in turns prevents vasoconstriction and the retention of salt and water, lowering blood pressure.
When is brain natriuretic peptide (BNP) released and by which organ?
Secreted by the ventricles in response to stretching, such as is seen in fluid overload.
What is the normal value of BNP?
<100pg/ml
When is BNP assessed?
To assess heart failure.
When does dehydration occur?
When fluid loss exceeds fluid gained.
What are 2 effects of dehydration?
- Increased blood tonicity
2. Cell shrinkage
Name 7 groups that are at high risk for dehydration.
- Confused (e.g. dementia)
- Comatose
- Bedridden
- Infants
- Decreased kidney function
- Elderly
- Highly concentrated tube feeding w/o additional water
Name 8 things that accelerate fluid loss, causing dehydration
- Diabetes insipidus
- Prolonged fever
- GI issues such as diarrhea, prolonged emesis, or NG drainage.
- Renal failure
- Hyperglycemia
- Medications such as diuretics or laxatives.
- Excessive diaphoresis
- Fistulas
10 signs of dehydration
- Mental status changes
- Fever
- Dry skin
- Dry mucous membranes
- Poor skin turgor
- Tachycardia
- Hypotension
- Seizures
- Decreased urine output
- Weight loss
3 symptoms of dehydration
- Dizziness
- Weakness
- Extreme thirst
What specific mental status changes might you see in a person with dehydration?
Restlessness and anxiety
What 4 lab test will show as elevated?
- Hematocrit
- Serum osmolality
- Sodium
- Urine specific gravity
What is the best way to replace missing fluids? What if dehydration is severe?
Oral replacement, IV replacement id severe dehydration
What type of solutions should be used when replacing fluids? What if blood pressure is too low?
Hypotonic solutions. Isotonic if BP is too low.
What is hypervolemia and what causes it?
An excess of isotonic fluid that occurs when compensatory mechanisms fail.
What are three effects of hypervolemia?
- Cell expansion
- Heart failure
- Pulmonary edema
Causes of hypervolemia?
- Too much IV replacement
- Blood volume replacement
- Fluid and sodium retention in heart failure
- Cirrhosis of the liver
- Kidney disease
- Some medications (e.g. Corticosteroids)
- Administration of hypertonic solutions (e.g. Albumin)
5 signs of hypervolemia.
- Rapid, bounding pulse
- Increased blood pressure
- S3 develops
- Distended veins
- Edema in the tissues and lungs
2 late signs of hypervolemia
- Falling blood pressure
2. Decreased cardiac output
What labs will be low or decreased in hypervolemia?
Low hematocrit, K+, and BUN
Decreased serum osmolality
What lab will be normal with hypervolemia?
Serum sodium
What might a chest X-ray reveal in a patient with hypervolemia?
Pulmonary congestion
3 ways to treat hypervolemia
- Restrict fluid and sodium
- Medicate to prevent heart failure and pulmonary edema (e.g. Diuretics)
- Treat cause of hypervolemia and any complications
4 functions of electrolytes
- Regulate fluid distribution
- Govern acid-base balance
- Function in the transmission of nerve impulses
- Instrumental in the production of energy and in blood clotting
What is a cation?
A positively charged particle
What is the main cation in extracellular fluid?
Sodium
What is a normal level of sodium (Na)?
135-145 mEq/L
What electrolyte is essential for impulse transmission in nerve and muscle cells?
Sodium
Sodium combines with other ions to maintain acid-base balance. What ions does it combine with?
Chloride (Cl-) and Bicarbonate (HCO3)
What serum sodium level is considered hyponatremia?
<135 mEq/L
How does hyponatremia affect ECF?
ECF will move into the cells causing them to swell.
5 Neurological signs and symptoms of hyponatremia once levels are below 125 mEq/L
- Headache
- Irritability
- Disorientation
- Lethargy
- Confusion
If serum sodium falls to 110 mEq/L, cerebral edema results. What 5 signs and symptoms would you expect to see?
- Stupor
- Delirium
- Ataxia
- Seizures
- Coma
Later death.
What 5 signs would indicate hyponatremia coupled with hypovolemia?
- Poor skin turgor
- Dry cracked mucous membranes
- Weak, rapid pulse
- Low blood pressure
- Orthostatic hypotension
What 4 signs would indicate hyponatremia coupled with hypervolemia?
- Edema
- Hypertension
- Weight gain
- Rapid, bounding pulse
5 labs to know with hyponatremia.
- Serum osmolality <280
- Serum Na+ <135 mEq/L
- Urine specific gravity <1.010
- Elevated Hct
- Elevated plasma protein
Treatment for mild hyponatremia with hypervolemia.
Restrict fluids and oral Na+ supplements
Treatment for hyponatremia with hypovolemia.
Isotonic IV fluids and high sodium foods.
Treatment with severe hyponatremia (<120 mEq/L) with hypovolemia.
ICU placement, Hypertonic IV solution administered slowly to avoid overload and diuretics such as furosemide.
How is hypernatremia defined?
serum Na+ >145 mEq/L
3 things hypernatremia can lead to.
- Seizures
- Coma
- Permanent neurological damage
What is the mortality rate with hypernatremia?
> 50%
Name 6 external causes of hypernatremia.
- Water deficit
- High protein feedings w/o adequate water
- Use of salt tablets
- High sodium foods
- Medications (e.g. Kayexalate)
- Excessive IV administration of a hypertonic solution
Name 5 disease processes that may cause hypernatremia.
- Inability to ingest fluids
- Hypothalamic disorders
- Hyperosmolar hyperglycemic nonketoic syndrome (severe water loss seen in type 2 diabetics)
- Diabetes insipidus
- Cushing’s syndrome
4 neuromuscular signs of hypernatremia
- Twitching
- Hyperreflexia
- Ataxia
- Tremors
5 early signs and symptoms of hypernatremia
- Restlessness
- Agitation
- Anorexia
- Nausea
- Vomiting
6 late signs and symptoms of hypernatremia
- Weakness
- Lethargy
- Confusion
- Stupor
- Seizures
- Coma
What is orthostatic hypotension an important indicator of?
Fluid deficit
3 lab tests to know in regards to hypernatremia
- Serum Na+ >145 mEq/L
- Urine specific gravity > 1.030
- Serum osmolality >300
4 Treatments for hypernatremia
- Correct underlying disorder
- Fluid replacement. If using IV, use a salt free solution such as D5W.
- Restrict sodium intake
- Diuretics to increase sodium loss
What is the main intracellular cation?
Potassium (K+)
What is the normal range for potassium?
3.5-4.5 mEq/L
How does potassium assist in keeping pH balanced?
Exchanges places with hydrogen (H+) ions to correct acidosis.
4 causes of hypokalemia
- Decreased intake
- Transcellular shift with alkalosis
- Non-renal losses such as vomiting and diarrhea, etc.
- Renal losses
7 disease processes that can cause hypokalemia
- Hepatic disease
- Hyperaldosteronism
- Acute alcoholism
- Heart failure
- Malabsorption
- Nephritis
- Acute leukemias
3 Cardiac signs of hypokalemia
- Weak and irregular pulse
- Orthostatic hypotension
- Palpitations
What 5 changes would you see on an EKG with a patient with hypokalemia?
- Flat or inverted T Wave
- U wave
- Depressed ST segment
- Ventricular arrhythmias
- Cardiac arrest
How does hypokalemia affect a patient taking digoxin?
Can cause the patient to become digitalis toxic.
3 Musculoskeletal signs and symptoms of hypokalemia.
- Weakness, especially in the legs.
- Leg cramps
- Decreased reflexes