Fluid Balance

how much of plasma is water?

90%

pereferal edema=

fluid is not making it back to circulation

what percent of body fluid is water?

60%

what can low bp be caused by?

not enough plasma

when kidneys stop producing urine it is known as?

renal failure

osmolality

a test that measures the concentration of all chemical particles found in the fluid part of blood.
-dependent on number of dissolved solutes in a fluid (sodium, glucose, urea)

expected osmolality

275-295 mOsm/kgH20

how do changes in osmolality effect water

can cause water to move to diff compartments
-osmosis

dehydration=

increases osmolality

overhydration=

decreases osmolality

how do we correct fluid imbalances

IV fluid administration
via osmosis
-MVT OF H20 FROM LOW SOLUTE TO HIGH SOLUTE (DILUTES)

tonicity

relative measurement of IV fluid
-will dictate mvt of fluid btw compartments
-IV fluid tonicity's main solutes: SODIUM & DEXTROSE
all fluids are dispensed according to their 'tonincity'

Tonicity categories

Isotonic= same as plasma (same osmolality)
Hypertonic= higher than plasma
Hypotonic= lower then plasma

If the fluid is isotonic how will stay in the compartment?

it will probably stay in its compartment equally, good quality circulation

if the fluid is hypertonic how will it move in the compartment?

water move from cells & interstitial fluid to plasma

when the solution has really high solute migration of water form intracellular compartment, used for cerebral edema. Gets the water out of the brain, it was cause dehydration in the cells but will save the area from injuring itself.

if the fluid is hypotonic how will it effect the compartment

Water moves from plasma to interstitial fluid


goal is to rehydrate the cells by pulling water in but of you give to much you can burst the cells

most dehydration is ?

isotonic, meaning you lose equal amounts if water & electrolytes

colloid fluids=

protein based

crystalloid fluids=

water based

2 basic iv fluids

colloid
crystalloid

Colloids

supply proteins into ECf
stay in circulation
-aka Plasma expanders
eg: tx of hypovolemic shock
contra in most other cases -no pass via capillaries & renal workload
EG: plasbumin, Alburex

how do know proteins will stay in the place we put them.

they are so large and need active transport to move, so it will stay. which will draw water to it for dilution. Good for someone with low bp or is bleeding.

why dont we usually use colloids or plasma expanders

you are increasing bp and increasing the work of all the organs

Crystaloids

Supply H20 & Electrolytes & other solutes (glucose)
can move btw ECF & ICF
-tonicity directs fluid mvt
esp NA+ amount
give glucose for energry

What is an example of fluid that will change from isotonic hypertonic in The Body

albumin 5%

What happens to dextrose once in the body

High dextrose is quickly utilized => domains of fluid becomes isotonic or even hypotonic
eg: D5 1/2NS (mildly hypertonic in the bag)

fluid resuscitation =

replacing deficts
goal= adequate perfusion=> rescue intravascular volume

routine fluid maintence

35ml/kg/day of water
potassium, sodium, & chloride
-50-100g/day of glucose to limit starvation ketosis

4/2/1 rule

4ml/kg/hr for 1st 10 kg of body weight
2ml/kg/hr for 2nd 10 kg of body weight
1 ml/kg/hr for the remaining kgs

Isotonic fluids:

Lactated Ringers
-NS (0.9%)
-5% albumin (colloid)
-Dextran 40 (colloid)
the two colloids become hypertonic in the body

NS 0.9% details

-Contents:
154mEq Na
154mEq Cl
-Category: isotonic
*resuscitation fluid #1 choice: adults 500mL bolus
-Side effects if longterm >2days
Hypokalemia
no dextrose

Lactated Ringer LR details:

-Contents: MORE ELECTROLYTES THEN NS
Na 130mEq
POTASSIUM 4 mEq
CALCIUM 2.7 mEq
chloride 109 mEq
Lactate 28 mEq
Category:
isotonic
s/E: hyperkalemia, no dextrose, high lactate,
contra in kids bc high lactate and high electrolytes

Hypertonic IV fluid (high glucose or sodium)

-D5NS
-D5LR
-D10W
-D5 0.45%NaCl (mild) D5 1/2 NS
3% NaCl

what hypertonic fluid is commonly used in surgery

D5NS

when would you use 3% saline

head injury to lower the ICP

when would you use 25% albumin

resuscitation if low volume in, is the choice

D 5.45 NS details:

Contents:
77 mEq Na
77 mEq Cl
50 mEq Dextrose

Category: hypertonic (osmolality=405 mOsm/L) in the bag

Side effects: cellular dehydration, hyponatremia
Pediatrics: 1st choice for maintenance fluids; check K+

25% Albumin details:

Contents
25% albumin
upto160 mEq Na

Category: Hypertonic

Caution:
Intravenous volume expander
25% Albumin IV => 3.5 times its volume of additional fluid into the circulation within 15 minutes

what patients would not benefit from hypertonic solutions

hypertension, renal failure, diabetic patients

Hypotonic solutions: fluid into cells

Hypotonic IV fluid (low NaCl)
-0.45% NaCl
-D5W
-3.3% dextrose, 0.3% sodium (2/3 1/3)
-D5 0.2% NaCl (mild)


E.g. dehydrated patient with high bloodwork solute
“Hypernatremic dehydration”

GI bleed tx

Stop contributing drugs:
NSAIDs
‘blood thinners’
Antiplatelets
Anticoagulants
Thrombolytics


Fluids
Blood transfusion ?

PPIs

assess: endoscopy or colonoscopy
big symptom is low BP

what can we give for blood loss

Red blood cells
Whole blood
Platelets
FFP

Electrolytes

-Positively or negatively charged in organic molecules
Essential to: nerve conduction, membrane permeability water balance, other critical body functions imbalances can be serious, fatal clinically --Most common issues potassium and sodium balance

hyponatremia sodium issue

< 135mEq/L Na Most common cause: Diuretic use, dehydration hyponatremic Tx: D5NS

hypernatremia sodium issue

> 145mEq/L
Most common cause: Kidney failure, high Na intake+++; dehydration hypernatremic
Tx: Restrict salt intake; Diuretics to remove Na+; if IV fluid = low Na !

Hyperkalemia potassium issue

K+>5 mEq/L
Most common cause: meds e.g. potassium sparing diuretics; renal disease.
Tx: Kayexalate (PO, NG) binds K+ in intestines

Hypokalemia potassium issue

K+