Fluids Pathophys Flashcards
IV Fluids & Management
what makes up intracellular fluid
- all fluid enclosed in cells by plasma membranes
- makes up ~2/3 of body water
- fluid volume is stable
IV Fluids & Management
what makes up extracellular fluid
- fluid outside of the cells
- Intravascular fluid (plasma): fluid component of blood
- interstitial fluid: fluid surrounding cells
IV Fluids & Management
what is the term that describes the distribution of water present in the body?
fluid spacing
IV Fluids & Management
what is first spacing?
- normal distribution of fluid in the intracellular and extracellular compartments
- extracellular fluids are distributed between the interstitial (tissue) and intravascular (plasma) compartments 75-25%
IV Fluids & Management
describe second spacing
- abnormal accumulation of interstitial fluid in the body (edema)
- can move back to first spacing
IV Fluids & Management
describe third spacing
- mobilization of body fluid to a non-contributory space rendering it unavailable to the circulatory system (ascites)
IV Fluids & Management
define osmosis
- spontaneous movement of water across semi-permeable membrane
- water moves from region of high solute concentration to a region of low solute concentration
- tries to equalize concentrations
IV Fluids & Management
define osmotic pressure
- hydrostatic pressure necessary to counteract the process of osmosis
- depends on the solut concentration (increases osmotic pressure with high solute concentration)
- NOT dependent on mass/size of molecules
IV Fluids & Management
describe tonicity
the capability of a solution to modify the volume of cells by altering their water content
IV Fluids & Management
define isotonic, hypertonic, and hypotonic
- isotonic: IV fluid concentration = plasma concentration
- hypertonic: IV fluid concentration > plasma concentration
- hypotonic: IV fluid concentration < plasma concentration
IV Fluids & Management
what would happen if a patient received IV water instead of normal saline?
RBCs would swell and burst
IV Fluids & Management
what is osmolar concentration
how much of a solute is present
IV Fluids & Management
osmolarity vs osmolality
- osmolarity: solute in solution based on 1L
- osmolality: solute in solution based on kilogram
IV Fluids & Management
major intracellular vs extracellular ions?
- intracellular: potassium
- extracellular: sodium
IV Fluids & Management
describe water balance in the body
- our body wants intake and excretion to be equal
- majority of intake: GI tract
- majority of output: urine
IV Fluids & Management
what center helps regulate water intake/output?
- hypothalmic thirst center
IV Fluids & Management
describe activation of hypothalamic thirst center
- stimulated when osmoreceptors detect an increase in plasma osmolality or a decrease in blood volume/pressure
- body releases ADH and aldosterone
IV Fluids & Management
describe feedback loop of hypothalamic thirst center
- drinking water inhibits thirst center
- inhibitory feedback: relief of dry mouth, activation of stomach/intestinal stretch receptors
IV Fluids & Management
role of anti-diuretic hormone (ADH) in thirst response
- hypothalamus stimulates release of ADH from posterior pituitary gland when dehydrated
- ADH works on the kidneys to recover water from urine
IV Fluids & Management
describe role of aldosterone with thirst
- kidneys increase production of angiotensin II which stimulates thirst and stimulates the release of aldosterone from the adrenal galnds
- aldosterone tells the kidneys to increase resorption of sodium in distal tubules (water will follow sodium)
IV Fluids & Management
common indications of IV fluid administration
4
- fluid resuscitation
- correction of electrolyte imbalances
- maintenance of fluids for patients that cannot take fluids enterally
- IV med delivery
IV Fluids & Management
2 categories of fluid administration
- crystalloid solutions
- colloid solutions
IV Fluids & Management
two components of:
* crystalloid
* colloid
- crystalloid: small molecular weight solutes (minerals, dextrose) and sterile water (more commonly used)
- colloid: large molecular weight solutes (albumin, blood products) and sterile water
IV Fluids & Management
describe what crystalloid solutions do in the body
3 components
- consist of aqueous electrolyte solutions w/ varying concentrations
- do not readily cross plasma membranes, but will cross capillary membranes
- can be isotonic, hypotonic, hypertonic, mixed, and concentrated
IV Fluids & Management
what are 2 isotonic crystalloid solutions?
- Normal saline (0.9% NaCl)
- Lactated Ringer’s (LR)
IV Fluids & Management
what are 2 hypotonic crystalloid solutions?
- Dextrose solutions (D5W or D10W)
- Saline Solutions (0.45% NaCl, .22% NaCl)
IV Fluids & Management
what are two types of hypertonic crystalloid solutions?
- 3% NaCl
- 5% NaCl
IV Fluids & Management
what are mixed crystalloid solutions?
2
- dextrose in saline solutions
- Isotonic bicarbonate
IV Fluids & Management
2 concentrated crystalloid solutions?
- 8.4% sodium bicarbonate
- 50% dextrose in water (D50W)
IV Fluids & Management
describe normal saline
- 0.9% NaCl
- contains equal mEg/L of Na+ and Cl-
- increase extracellular volume w/ no change in intracellular volume
- indicated: fluid resuscitation, maintenance of fluid therapy, IV drug admin
- risks: hyperchloremic non-anion gap metablic acidosis, fluid overload
IV Fluids & Management
describe lactated ringers
- contains Na+, Cl-. K+, Ca2+, lactate
- increases extracellular volume, minimally increases intracellular volume
- mild buffering action which prevents acidosis
- indicated: fluid resuscitation, maintenance fluid therapy
- risks: hyperkalemia, fluid overload, accumulation of lactate (only in liver failure)
IV Fluids & Management
describe use of dextrose solution
- can be 5% or 10% dextrose (D5W, D10W)
- increases extracellular and intracellular volume
- indications: correction of free water deficit (hypernatremia), maintenance fluid therapy (hypoglycemia, ketosis)
- risks: hyponatremia, hypokalemia, hyperglycemia, cerebral/pulm edema