Fluids Flashcards
two types of body fluids? what are they separated by?
- Intracellular- Inside Cells
- Extracellular- Outside Cells
-Both fluids are separated by the cell membrane
-Cells create and maintain the differences between intra- and extracellular fluid
how is 60% of body water split up
40% BW is intracellular
20% BW is extracellular
what is ICF mainly composed of? is it homogenous? pH?
– Primarily a solution of potassium, organic anions, proteins
– ICF is not homogeneous in the body
– pH is close to 7.0
fluid compartments are in _____ _____
osmotic equilibrium
what is ECF mainly composed of? how is it subdivided further? pH?
– Primarily a NaCl and NaHCO3 solution
– ECF is subdivided into three subcompartments:
* Interstitial Fluid (ISF) surrounds the cells, but does not circulate. It comprises about 3/4 of the ECF.
* Plasma circulates as the extracellular component of blood. It
makes up about 1/4 of the ECF.
* Transcellular fluid is a set of fluids that are outside of the normal compartments (CSF, Digestive Juices, Mucus, etc.)
– pH is 7.40-7.45
what are two things that can influence PCV
deydration and blood loss
blood volume of pigs
Blood volume- 65-75 mL/kg (6.5-7.5%)
what is the net effect of drawing out fluid?
lymphatic systems or else you get edema
P vs pi functions for starlings equation
P = pressure pushing fluids out
pi = oncotic pressure drawing fluids in
what is the endothelial glycocalyx later (EGL)?
Small pore system in the transvascular semi-permeable membrane that covers the endothelial intercellular clefts, separating plasma from a
‘protected region’ of the subglycocalyx space which is almost protein-free
what is the estimated EGL volume estimated to be
EGL’s volume is estimated at 700 mL in a person
most of the filtered fluid returns to the circulation as _____
lymph
features of the EGL (4)
- Is semi-permeable with respect to anionic macromolecules such as albumin and other plasma proteins
- Impermeable to Dextran molecules of 70 kDa and red cells
- Is compromised in systemic inflammatory states such as diabetes,
hyperglycaemia, surgery, trauma and sepsis - Therapeutic drugs that protect or restore the EGL include N-acetyl
cysteine, antithrombin III, hydrocortisone and sevoflurane
anesthesia
EGL is an _____ interface between blood and the capillary wall
active
what determines if the capillary bed filters big molecules or not
EGL and basement membrane fenestrations determine if the capillary bed filters big molecules (albumin) or not
to maintain volume and electrolyte composition (2)
– A.) Sensible losses; urine production (1-2 mL/kg/h)
– B.) Insensible losses; Breathing, faeces, sweating (1 mL/kg/h)
do crystalloids have oncotic pressure?
nope
what can large volume of crystalloids cause
Large volumes can cause excessive extravasation
when can you use crystalloids to treat blood loss
Blood loss of less than 10% blood volume can be effectively treated with crystalloids
Higher losses would require too much time and fluid
how long does hypertonic saline last related to volume expansion
Volume expansion lasts less than 60 min
how long do colloids stay in the vascular compartment for? what is the rule of replacement?
6-16 hours
1:1 replacement
are synthetic colloids currently recommended? why or why not?
– Shock reversal achieved equally fast with synthetic colloids or crystalloids
– Use of colloids resulted in only marginally lower required volumes of resuscitation fluid
– Low molecular weight hydroxyethyl starch (Pentastarch) may impair renal function
what does evidence show about isotonic solutions vs colloids solutions related to treating hypovolemia
- Evidence has shown that isotonic solutions are not very different from colloid solutions in terms of effectiveness for treating hypovolemia
– It is estimated that only 20-30% of isotonic solutions remain in the vascular space after 1-hour
– Colloid solutions remain 100%
what do we see with <5% dehydration
History of fluid loss but no findings on physical examination
what do we see with 5% dehydration
Dry oral mucous membranes but no panting or pathological tachycardia
what do we see with 7% dehydration
Mild to moderate decreased skin turgor, dry oral mucous membranes, slight tachycardia, and normal pulse pressure.
what do we see with 10% dehydration
Moderate to marked degree of decreased skin turgor, dry oral mucous membranes, tachycardia, and decreased pulse pressure.
what do we see with 12% dehydration
Marked loss of skin turgor, dry oral mucous membranes, and significant signs of shock.
dehydration vs blood volume
- Dehydration is total body water; Calculated based on total body weight, not just the 60% of total water
- Blood volume (6-10%) is based on a fraction of total body water, depending on species
what things do we need to consider related to effects of fluid on? (4)
- PCV, TP
- Dehydrated patient: High PCV and TP
- Blood loss: May not change PCV and TP until the body retains fluids through kidney actions. Then, low PCV and TP
- Administering crystalloids in the presence of blood loss: Acute lowering of PCV and TP
