fluids Flashcards
pathophys of thirst
hypothalamus responds to osmoreceptors that trigger thirst in response to hypertonic solution
fluid overload is commonly the result of these dz processes
heart failure
liver failure
renal failure
iatrogenic
fluid resuscitation vs maintenance
someone who is dry coming out of the OR
giving a bolus is resuscitation
maintenance is for NPO
how is lactate solution better from resuscitation
acidosis occurs form fluid loss and the lactate solution and lactate meatbolism counters this
normal fluid requirements-faily adult
2-3 l A DAY
Humans require how many ml of water for every square meter of surface area
how do you calculate body surface area
1500
height in cm x weight in kilos/3500
how many ml/hr of IV fluid does the average adult need
100-125 ml/hr to meet daily fluid requirements
daily fluid requirement equation for average adult
based on weight
1500ml of water for every square meter of surface area.
An average adult has a surface area of about 1.7 square meters. 1.7 x 1500 = 2.55 liters a day.
daily electrolyte requirements
Na
K
Glucose
Na: 1-2 mEq/kg (140)
K: .5-1 MeQ/KH( 70 MeQ)
Glucose: 500 kcal
28 yo male NPO for maintenance order
D5NS w/ 20 mEk KCL at 125 ml/hr
D5W
5% Dextrose (calories) in water
1/2 NS
.45% of Na in 1L
NS
NaCL
0.9grams of NaCl in 1 L
lactated ringer
electrolytes no calories
- Used for fluid resuscitation after blood loss d/t trauma, surgery or burns
- Used very routinely in the perioperative setting for
- Can be used for fluid resuscitation and fluid maintenance
D5W in 1/2 NS
has calories
good maintenance fluid
Two main types of fluids
crystalloids (small solutes; can move a little freely)
and
colloids (big solutes; like blood).
crystalloids
administered as maintenance fluids nPO pts, used fro hypovolemic resuscitation in trauma
colloids
fluids that in addition to mineral salts also have large proteins
less likely than crystalloids to cause edema\
usually given 250ml of albumin
used for special populations and not administered very often
what do you need before administering colloids
need a type and cross match for compatibility
why don’t we use colloids
albumin expand volume better
less edema
but greater mortality
in what patient population would we use colloid fluid
elderly who can’t tolerate high volume resuscitation
severe diarrhea with low serum albumin
nephrotic syndrome
how to determine fluid needs PO
• As a general rule, it is safe to assume that a patient just leaving the OR is going to be down 1 to 2 liters of fluid.
maintenance for breast
for bigger cases, i.e., whipple will need resuscitation threapy too
should check urine output
blood tests
skin, BP, HR, RR, cap refill and lung sounds to determine fluid needs
also check CXR out of OR (looking for fluid accumulation)
always ask the anesthesiologist if there was a foley, what fluids where given, if there are JP drians
when would JP drains be used PO
JP drains are used when there is an empty cavity to help remove fluid that automatically wants to fill old tissue space
ideal pt
UO and labs
urine output is between 50-100 ml/hr
labs are within normal limits
Na 135-145
K 3.6-4.8
creatinine <1.2
what does a dry pt look like
NPO for a minute elderly DM was having diarrhea or vomiting pre-op tachy weighs less than pre OP
decreased skin turgor and low CVP
what does an overloaded pt look like
hx of chf
FLUID INTAKE GREATER THAN OUTPUT
Raised CVP, lung crackles, weight is above pre ob
Na may be low
CXR=Pulm Edema
treating perfect pt
if able to take PO heplock the IV when pt beings to eat
remove foley
check electrolytes fro 24 hrs -48 hrs
monitor for signs of fluid overload or fluid deficit while in house
treating dry pt
give an initial isotonic fluid bolus 500-1000ml
use smaller amoutns in elderly
follow V/S UP BP
follow labs for electrolyte abnormalities
if you’re concerned about the pts fluid status consider placing a foley or keeping current foley to track urine output more closely
tx for overloaded pt
Restrict fluid intake. If patient requires maintenance fluids, give 500ml over first 24 hours (20ml/hr).
•Consider diuretics (e.g., Lasix) if patient has signs of pulmonary edema. (crackles)
- Follow electrolytes closely, and correct abnormalities.
- Severe cases in the setting of renal failure may require dialysis.
cations
Na+, K+, Mg+, Ca2+
anions
Cl-, HCO3-, PO43- (and other phosphates), and negatively charged proteins.
Concentration of a solution expressed as the total number of solute particles per kilogram.
osmolarity
interstitial fluid accoutns for
[~9L, ~15% of body weight]
intravascular fluid accounts for
[~5L, ~5% of body weight
the spontaneous movement of molecules from areas of high concentration to areas of low concentration.
• Molecular diffusion
what effects osmotic activity
- The concentration of each solution (the greater the difference, the greater the osmotic pull).
- Temperature.
- Surface area to volume ratio.
- The permeability of the membrane (if more permeable, water will diffuse faster than solutes).
two types of osmoles
Effective osmoles, which DO NOT freely move across a membrane (e.g., electrolytes)
Ineffective osmoles, which DO freely move
electrolytes are an example of effective or ineffective osmoles
Effective osmoles, which DO NOT freely move across a membrane
give an example of ineffective osmoles
Ineffective osmoles, which DO freely move
(e.g., urea, ethanol, methanol).
The concentration of a solution, minus ineffective osmoles, is called
The concentration of a solution, minus ineffective osmoles, is called tonicity.
Isotonic ismols
270-300 mOsm/L
hypertonic
> 300 mOsml/L
Hypotonic ismols
<270 mOsm/L
most of our body weight is intracellular or extracellular
intracellular
Where do our fluids go?
- 800-1500ml in urine
- 0-250ml in stool
- 600-900ml through skin and lungs
The ______ triggers thirst with baroreceptors in response to hypovolemia.
- The renin-angiotensin system triggers thirst with baroreceptors in response to hypovolemia.
- Oropharyngeal dryness
- Psychological factors
increased fluid loss by system
- GI: vomiting, diarrhea
- Renal: diuresis
- Vascular: hemorrhage
- Skin: burns, fever
- Lungs: tachypnea, mechanical ventilation
daily fluid requirement equation for elderly
1500ml PLUS 10-15ml per kg over 20
when you foley out indicate a fluid deficit
ins and outs indicate fluid deficit (less than 30ml an hr)
