Clinical Disorders of ECF Volume Flashcards
discuss the fluid distribution across the body compartments
- total body water (TBW) = 60% of total boday weight
- TBW = intracellular fluid (2/3) + extracellular fluid (1/3)
- ECF = plasma (1/4) and intersitial fluid (3/4)
- TBW = intracellular fluid (2/3) + extracellular fluid (1/3)
what are the major causes of ECF volume contraction
- diarrhea
- burns
- sweating
- diuretics
- kidney failure
define mild, moderate, and severe ECF volume contraction
- mild: ECF loss < 5%
- moderate: ECF loss 5-10%
- severe: ECF loss > 10%
symptomatology of mild ECF loss (< 5% )
- thirst
- dry mucous membranes
- poor skin turgor
symptomatology characteristics of moderate ECF loss (5-10% loss)
- orthostatic hypotension
- tachycardia
symptomatology characteristic of severe ECF loss (>10%)
- possible shock
- hypotension
- tachycardia
- tachypnea
- poor capillary refill
- confusion
right heart catheterization - uses, pros & cons
- assess pressure in the pulmonary artery via the right heart
- pros: provides a definitive diagnosis of volume status (hyper-, hypo, euvolemic)
- cons: invasive
what defines orthostatic pressure?
= any of the three changes when patient goes from supine to sitting or sitting to standing:
- a 20 mmHg drop in systolic pressure
- a 10 mmHg drop in disatolic pressure
- rise of 20 beats/min in pulse
what is the “fluid challenge” and what is it used to determine
- use: used to determine if fluid replacement would be effective in a patient with a contracted ECV
- test:
- patient supine with upper body at 45 degrees
- legs are lifted above head and their CO is monitored
- if CO improves, it indicates they would be responsive to fluid replacement
when assessing a hypervolemic patient
- what should you look for/what will you likelhy see on an exam?
- what pertinent medical history should you ask about =?
- exam
- lung rales on exam
- EDEMA
- pulmonary edema on chest xray
- pitting edema
- PMHx:
- want to rule out disease that would decrease ECBV and lead to hypervolemia
- CHF
- chronic kidney disease
- cirrhosis
- want to check past echo
- want to rule out disease that would decrease ECBV and lead to hypervolemia
common symptoms of hypervolemia
common symptoms of hypervolemia
- weight gain
- pitting edema
- dyspnea (difficultly breathing)
- orthopena (difficultly breathing when sitting up)
general treatments for hypervolemia
- diruetics
- fluid restriction
- sodium restriction
- strict monitoring of intake/ouput
define volume “contraction” and “expansion” in terms of fluid shifts
based on volume of fluid in the extracellular space
- volume contraction = decrease in ECF
- volume expansion = increase in ECF
isosomotic fluid contraction
- describe the volume status of compartments
- causes?
- occurs with a loss of isosomotic fluid
- osmolarity of ECF remains the same, so there is no shift in fluid in or out of the ECF
- ECF volume = decreased
- ICF volume = the same
- osmolarity of ECF remains the same, so there is no shift in fluid in or out of the ECF
- causes:
- diarrhea
- fluid loss at burn sites
hyperosmotic volume contraction
- volume status of each compartment?
- causes?
- caused by a loss of hypotonic fluid from the ECF. remaining ECF fluid is hypertonic, and draws in water from the ICF to equilibrate osmolarity
- ECF vollume = decreased
- ICF volume = decreased
- causes
- sweating
- dehydration
hypoosmotic contraction
- volume status of each compartment?
- causes?
- hypertonic fluid is lost from the ECF. the fluid remaining in the ECF is hypotonic to the ICF, so water diffuses into the ECF
- ECF volume = decreased
- ICF volume = increased
- causes:
-
aldosterone deficiency:
- results in less Na+ reabsorption at the collecting duct. Na+ remains in the tubular fluid, and the hypertonic filtrate is exceteed
-
aldosterone deficiency:
isoosmotic volume expansion
- volume status of compartments?
- causes?
- due to an increase of isotonic fluid in the ECF
- osmolarity across compartments remains the same, so no fluid shifts
- ECF volume = increased
- ICF volume = the same
- osmolarity across compartments remains the same, so no fluid shifts
- example: excess amount of IVF (IV fulid) aministered
hyperosmotic volume expansion?
- volume status of compartments?
- causes?
- an increase in osmolarity in the ECF. water is drawn from the ICF into the ECF to equilibrate osmolarity
- ECF volume = inceases
- ICF volume = deceases
- cause: consuming foods high in sodium
hypoosmotic expansion
- volume status of compartments?
- causes?
- an increase in free water in the ECF decreases ECF osmolarity, and water diffuses from the ECF into the ICF until osmolarities equilibrate
- ECF volume increases
- ICF volume increases
- causes:
- SIADH: excess reabsoprtion of water due to ADH
- polydispia: excess water consumption
