Flashcards in fluid and blood product management Deck (105)
what is the major component of the body?
water (50-70% of body weight)
what is water percentage influenced by?
-age (decreases with age; water babies vs. dry elderly)
-tissues (fat holds less water than lean tissue; thin person has more water than obese person)
describe intracellular fluid volume
-2/3 of total body water (28 L in a 70 kg male; 40% total body weight)
-fluid inside all cells, aqueous medium
-most of the potassium is here
describe extracellular fluid volume (ECF)
-1/3 of total body water (14 L in 70 kg male; 20% total body weight)
-fluid outside cells in cardiovascular system, organs, and interstitial spaces
-most of sodium is here
-two compartments: plasma volume (PV) and interstitial fluid volume
*compartment that is replaced with fluid management
describe plasma volume (PV)
-1/4 of ECF (3.5 L)
-intravascular fluid, but outside the erythrocytes
-8-9% of total body water
describe interstitial fluid (ISF)
-3/4 of ECF (10.5 L)
-extravascular, interstitial fluid, extracellular
-separated from the plasma volume by the walls of the blood vessels
-very little in the form of free fluid (increased clinically is edema)
*lymph, cavity fluid (peritoneal, pericardial, pleural), transcellular fluids (salivary, hepatic, biliary, pancreatic, dermal, mucosal, etc.)
what happens continuously between the different fluid compartments?
there is a continuous exchange of water between the different fluid compartments
what forces influence the movement of fluid between the compartments?
what is hydrostatic pressure?
the pressure within the capillaries from the weight of the blood and the pressure from the cardiac pumping mechanics
what results from hydrostatic pressure?
-small amounts of intravascular plasma volume moving into the interstitial fluid compartment
*typically, this water returns to the venous capillaries from the interstitial fluid compartment maybe through the lymph
what is osmotic pressure?
the hydrostatic pressure that must be applied to the solution of greater concentration to prevent water movement across the membrane
*forces wanting to keep fluid in; "pulls" on fluid
how does osmotic pressure work?
when two compartments are separated by a semipermeable membrane with aqueous solutions of unequal concentrations, the water will move from the more dilute to the more concentrated solution in an effort to equalize the concentrations
which end of the capillary has a net loss (fluid moving out)?
*more loss on arterial end than gain on venous end
which end of the capillary has a net gain (fluid coming back in)?
what does the solutions that exist in the compartments contain that accounts for osmotic forces?
-Na+: plasma, interstitial (extracellular)
what is the purpose of fluid management?
maintain tissue perfusion
what is tonicity?
compares osmolality of solutions; the effect of a solution on the cell volume
-osmolality of solution is the same (isoosmotic) as that of body fluids
-nothing happens to the cell
*NS, LR, plasmalyte
*plasmalyte is very similar to normal plasma
*NS is isotonic but is different and too much can create acidosis
-osmolality of solution is higher than body fluids causing water to move out of cells
*5% NS, 10% Mannitol
*neuro use; helps shrink cerebral edema or shrinks cerebral tissue to allow surgeon easier access to site and closure of cranium
-have a lower osmolality than body fluids causing absorption of water by cells
-cell swells (bursts)
-rarely ever want this to happen
*1/2 NS, D5W (starts off isotonic but the metabolism of glucose causes to become hypotonic and absorb water
*avoid in neuro patients (increases swelling)
*avoid with any ischemia (glucose products increase damage)
what contributes to volume deficit?
-prolonged NPO time
-excessive blood drawn
what clinical signs may be seen with volume deficit?
-blood pressure: orthostatic hypotension; > 20 mmHg indicates a deficit of 6-8% (w/o vasodilation); decreased BP with inspiratory gas flow (PPV decreases VR)
-heart rate: increases with hypotension; r/o medication related
-mucous membrane moisture: dry
-skin turgor: poor
-urine output: decreased
what is considered mild dehydration?
-less than 5% wt loss
-dry mouth, malaise, decrease UOP
-normotensive, normal cap refill
May be d/t vomiting or diarrhea
what is considered moderate dehydration?
5-10% reduction in body weight
-lethargy, loss of appetite, thick mucous membranes, oliguria, eyes sunken, depression of anterior fontanelle (in infants up to 6 months)
-normotensive, HR increased, capillary refill slowed to 3 seconds
what is considered severe dehydration?
> 10% decrease in body weight
-hypotension less than 60 mmHg, tachycardia, mottled cool skin, cap refill greater than 3 sec., anuria
*if suspected, give 10-20 ml/kg bolus (caution with CHF)
what contributes to volume excess?
-excessive fluid administration
-cirrhosis of the liver
what procedures put the pt. at risk for fluid excess?
transurethral resection of the prostate (TURP) and hysteroscopy
-both open up sinuses which absorb irrigation fluid
*best option is a regional with these procedures since Na+ changes are easily indicated with CNS changes which can not be assessed with GA
*know pre op Na+ levels
what clinical signs would indicate volume excess?
-edema: scleral, conjunctiva, pulmonary edema if severe
-diuresis: > 100 ml/hr
-initially HTN, progresses to hypotension if cardiac failure
**if in CHF, treatment should be completed before selective anesthesia; unless surgery is a matter of death, delay and consult cardiology
how does volume deficit influence sodium concentration?
-electrolyte free water is lost, serum sodium and serum osmolality increase
-d/t inadequate water intake, fever, loss of fluid from burns