Week 2 Flashcards
Intracellular
2/3 of body fluid; most in skeletal muscle mass; most water here
Extracellular
⅓ body fluid
Intravascular space, plasma and blood cells
Extracellular contains what body fluid compartments?
- Intravascular
- Plasma 3.5L
- 2.5L erythrocytes, leukocytes and thrombocytes - Interstitial
- Space between cells, tissues, organs and blood vessels
- 10L adult - Transcelluar
- CBS, pericardial sac, intraocular space, pleura space, peritoneal cavity
What body compartment do we lose water from first?
vascular space first, then interstitial space, then intracellular space
When we replace water, we replace intravascular, interstitial and intracellular
Third spacing
the movement of bodily fluid from the blood, into the spaces between the cells. The term “third spacing” also describes the accumulation of fluid from the blood within body cavities, intestinal areas, or areas of the body that normally contain little fluid.
Early evidence of third spacing
Decrease in UOP (first sign)
Other signs: increase HR, decrease BP, decrease CVP, edema, increase body weight, imbalance I&O, peripheral and dependent edema
When might 3rd spacing occur?
ascites, burns, peritonitis, bowel obstruction, massive bleeding into joint or cavity, sepsis
When we are referring to normal levels of electrolytes, what fluid compartment are we referring to?
EXTRACELLULAR Sodium 142 Potassium 5 Calcium 5 Magnesium 2 Chloride 103 Bicarbonate 26
normal electrolyte values in intracellular space
Potassium 150 Magnesium 40 Sodium 10 Phosphate 150 Bicarbonate 10
osmosis and osmality
movement of water in relation to the number of dissolved particles
HIGH to LOW concentration
Diffusion
movement of substance from high to lower concentration
Filteration
kidneys filter 180 L/day
hydrostatic pressure and capillaries filter fluid out of intravascular into the interstitial space
Hydrostatic pressure
the pressure that is exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity.
Plasma oncotic
Plasma proteins
Sodium potassium pump
Active transport, requires E
a protein that has been identified in many cells that maintains the internal concentration of potassium ions [K+] higher than that in the surrounding medium (blood, body fluid, water) and maintains the internal concentration of sodium ions [Na+] lower than that of the surrounding medium.
What can lack of albumin lead to?
Albumin (plasma proteins) line vessel walls so fluid stays inside vessel → when we don’t have this, fluid can go out into interstitial space (increased permeability) → create fluid/volume deficit and edema
Why does replacing plasma proteins decrease peripheral edema?
keeps fluid inside cells
What happens when we have edema because of too much intravascular volume?
blood vessels get larger, and there are not enough plasma protein levels (hypervolemic), even if plasma proteins are normal → causes peripheral edema. If we increase protein intake we see a decrease in peripheral edema (high protein diet important)
Routes of gains and losses: kidneys
- 5L/24 hour average adult (lose)
0. 5-1mL/kg/hour
Routes of gains and losses: skin
~600mL/day (sweat)
Routes of gains and losses: lungs
Insensible loss → no way to measure how much fluid we lose through lungs
Lose about 400mL/day
Routes of gains and losses
100 mL/day (lose); increase with diarrhea, decrease with constipation
Lab tests for evaluating fluid status: osmolality
the concentration of fluid that affects the movement of water between fluid compartments by osmosis
275-300 = normal blood osmolality
Lab tests for evaluating fluid status: Urine specific gravity
Measures ability of kidneys to concentrate urine and save water
Goes up w dehydration
Does down with fluid volume overload
Dependent upon normal kidney function
normal is 1.010 to 1.025
Lab tests for evaluating fluid status: BUN
Breakdown of nitrogen product in proteins
Decrease kidney function, dehydration, increase protein intake increases BUN
Malnutrition decreases BUN
BUN is dependent on hydration status
normal is 10-20 mg/dL
Lab tests for evaluating fluid status: Creatinine
In-product of muscle metabolism
NOT affected by hydration status
Most reliable lab test for kidney function
normal is 0.6-1.4 mg/d
Lab tests for evaluating fluid status: hematocrit
Percent of RBC in whole blood
Dependent upon volume
Rule of 3’s → hematocrit should be 3x hemoglobin if the patient has adequate fluid volume status. If you have fluid volume deficit, hemoglobin takes up more than the plasma (higher than 3x hemoglobin)
normal is 42%-52% for males and 36%-48% for females
Fluid volume excess, fluid volume deficit and dehydration/polycythemia impact on hematocrit
Fluid volume excess → decrease in hematocrit
Fluid volume deficit → excess hematocrit
Dehydration, polycythemia → increase hematocrit
Atrial natriuretic peptide (ANP)
Decreases BP and volume
a. Synthesized, stored and released by muscle cells of the atria
b. Excretion is enhanced by increases in atrial pressure, endothelin (powerful peptide vasoconstrictor-released from damaged endothelial cells in kidneys or other tissues) and sympathetic stimulation
c. Also conditions that lead to volume expansion - hypoxia, increased cardiac filling pressures
d. Expect increased levels in PAT, hyperthyroidism, subarachnoid hemorrhage and small cell lung cancer
ANP normal value
20/77ng/L
brain natriuretic peptide (BNP)
Stored in ventricles
Released when diastolic pressure in ventricles rises
normal = less than 100 (values over 100 indicate CHF)
NOT an emergency lab value
Hemostatic mechanisms: Kidneys
Regulate ECF volume and osmolality by selective retention and excretion of body fluids
Regulation of electrolyte levels in ECF - selective retention and excretion
Regulation of pH of the ECF by excretion or retention of hydrogen ion and/or bicarbonate ions (HCO3)
Hemostatic mechanisms: kidney failure
Can result in multiple fluids and electrolyte abnormalities
Hemostatic mechanisms: Heart
Trying to maintain adequate pumping
Fluid volume deficit → increase HR because not getting enough 02 and nutrients out to tissues
