2 - Fluid Disorders Flashcards
TBW
Total Body Weight
for Male & Female
**Male = 60% Female = 50%**
% of body weight
TBW
Total Body Weight
for
Pediatrics
Pediatrics = 60-70%
TBW
Total Body Weight
for
Elderly Male & Female
Elderly Male = 50%
Elderly FEMALE = 45%
TBW
Total Body Weight
for
OBESE
Decrease by 5%
if >130% over the IBW (ideal body weight)
- *Split of Total Body Water**
- *ECF / ICF / ISF / IVF**
2/3 ICF (intracellular Fluid)
1/3 ECF (Extracellular Fluid)
broken down to:
3/4 ISF (Interstitial Fluid)
&
1/4 IVF (Intravascular fluid)
Body Fluid Composition
TBW = ICF + ECF (ISF + IVF)
for a Male, 60% of weight is TBW
Tonicity
Fluid Tension between ECF & ICF
Extracellular Fluid - Intracellular Fluid (2/3 of TBW)
Weight of particles in a compartment that can Attract fluid
depend on relative solute permeability
OsmaLALity
Definition and Range
Total Solute concentration
given a weight of water in a given compartment
- *Collected or Measured** Plasma OsmoLALity:
- *280-295** mOsm/kg h2o
OsMOLARity
Osmolarity (mOsm/L H2O) =
2x[Na+] + glucose/18 + BUN/2.8
- *CALCULATED**
- compared to OsmoLALity, which is collected/measured*
Qualitative measure of TBW
↓ pOsm implies EXCESS water
↑ pOsm implies LACK of water
Regulation of Water Metabolism
Water Intake
THIRST is the mechanism to increase water intake
↑pOsm (lack of water)
↓ECF or BP
WATER EXCRETION
AVP = Arginine Vasopressin
major determinant of water loss
Water Balance
Water Gain
Sensible = Drinking Fluids / Eating Solids
Insensible = 250mL
From Metabolism / not measurable, but need to be taken account for
Water LOSS
Sensible = Urine / Intestinal / Sweat
Insensible = 600
from lungs / skin
AVP
Arginine Vasopressin
an ADH hormone synthesized in the Hypothalmus
stored in the posterior pituitary
Major Determinant of WATER LOSS
Water Excretion
Vasopressin Receptors
AVP
V2: Renal COLLECTING DUCT
<–Resorption of water via aquaporin-2 channel
decreases water excretion
V1A: Vascular Smooth Muscle
vasoconstriction / cardiac hypertrophy
V1B: Stress Reactive
release ACTH & Endorphin
What stimulates the RELEASE of AVP?
↑pOsm or ↓BP
NAUSEA**
Pain / Anxiety
- *Medications**:
- *Nicotine** / carbamezapine / TCA’s
- *SSRI’s** / opiates / haloperidol
Labs / Vitals / Symptoms
for HypoVolemia
- *Vitals**
- *↑HR** , orthostatics , ↓BP (severe), ↓Urine output
Labs
conc. urine , ↑BUN,
↑SCr // ↑Na+ (severe)
- *Symptoms**
- *weakness / syncope** / confusion / THIRST
- *↓ skin turgor / dry mouth**
Causes of dehydration which can lead to hypoVolemia
Increasing Age / Medications
INSENSIBLE Losses
Sweat / burn / HYPERVentilation
GI Losses
Vomiting / Diarrhea / biliary
- *Diabetes Insipidus** = AVP issues
- *Central** (neurogenic) - ↓ AVP secretion
- *Nephrogenic** = RESISTANCE to AVP effect
What type of VOLUME THERAPY?
Goal is to maintain ORGAN PERFUSION
by treating the intravascular hypovolemia
RESUSCITATION
What type of VOLUME THERAPY?
Goal is to Replace Volume Lost
REPLACEMENT
What type of VOLUME THERAPY?
Goal is to PREVENT Dehydration
consider BOTH sensible & insensible losses
MAINTENANCE
CRYSTALLOID
Volume Therapy
FLUID + ELECTROLYTES
replaces water & electrolytes
readily available / better tolerated / 1st line
Ex:
0.45% / 0.9% NaCl // LR // D5W
COLLOID
Volume Therapy
PRBC / Albumin 5% / 25% hetastarch
HUMAN PRODUCTS
used for I_ntravascular Volume (IVF) EXPANSION_
large molecules stay in the VASCULAR space
ISOTONIC
Replacement Fluid Tonicity
SImilar to Plasma, no fluid shifts
0.9% NaCl & LR’s
HYPERtonic
Replacement Fluid Tonicity
GREATER than PLASMA
IC –> EC fluid shifts
intracellular to extracellular
3% NaCl
HypoTonic
Replacement Fluid Tonicity
< 150 mOsm/L
flows BACK <– into Intracellular Space
EC –> IC
0.2% NaCl
Crystalloid Characteristics
Dextrose 5% is isotonic
hypotonic solution
BUT it causes increases in ICF / ISF / IVF
- Dextrose is slowly distributed
Colloid Characteristics
NO Intracelular Movement
Lactated Ringers & 0.9% NaCl
USES
LR contains K+, not good for patients with RENAL failure
Useful for hypotensive patients
IVF EXPANSION
(intravascular)
Since they are ISOTONIC, there is no fluid shift
does NOT enter any cells
commonly used in general surgery / neurosurgical poulations
since there is a LOSS of a lot of blood –> need to expand volume
D5W
Uses
- *ISOTONIC**
- BUT it* INCREASES ICF / ISF / IVF
The Dextrose provides OSMOTIC Activity to prevent hemolysis
Effective admin of a hypotonic solution“free water”
Watch out for:
HYPERglycemia &hypoNatremia
0.45% NaCl or 0.45% NaCl/D5W
USES
Able to REPLACE MORE Free water vs NS
Useful in:
HYPERNatremic Patients
&
Replacing INSENSIBLE water loss
dextrose can add calories
- *RESUSCITATION**
- *Management of HypoVolemia**
*ONLY if S/Sx of SHOCK
Bolus Dosing with 250-1000mL of
0.9% NaCl or LR
goal is to EXPAND IVF volume, need blood purfusion –> vital organs FIRST
Monitor:
BP / HR / Urine Output / CNS symptoms
MAY REPEAT if still SYMPTOMATIC
REPLACEMENT
Management of HypoVolemia
- *Calculate:**
- *FREE WATER DEFICIT**
- based on SODIUM concentrations*
MAINTENANCE
Management of HypoVolemia
Goal is to:
Prevent Dehydration
while administering daily water requirements
check comorbidities
revie patient’s electrolytes
&
nutritional status
Daily Fluid Requirements
(Maintenance)
Based on Volume Status
Dehydration / Post-OP / Euvolemia / Elderly or CHF
- *Dehydation**
- *45** mL/kg/day
- *Post-Operative**
- *40** mL/kg/day
- *Euvolemia**
- *35** mL/kg/day
- *Elderly or CHF**
- *30** mL/kg/day
Daily Fluid Requirement
(Maintenance)
Alternative Method - PEDIATRICS
- *for the 1st 10kg**
- *100** mL/kg/day
- *for the 2ND 10kg**
- *50** mL/kg/day
- *for WEIGHT > 20kg**
- *20** mL/kg/day
What Fluid & how much for this patient?
Post-OP patient with EBL of 500ml
(estimated blood loss)
FIRST
LR or 0.9% NaCl @ 40 mL/kg/day
useful in surgery - loss of a lot of blood // post-op pt
after 24 hours, THEN
D5W/0.45% NaCl @ 35 mL/kg/day
??? // euvolemic (normal volume)
What Fluid & how much for this patient?
HypoTensive Patient
LR or 0.9% NaCl @ 45 mL/kg/day
useful in HypoTensive Patients
&
low BP will lead to AVP release –> WATER excretion
dehydration is 45 mL/kg/day
What Fluid & how much for this patient?
NPO Cardiac patient w/ K+ level 3.4 mEq/L
D5W/0.45% NaCl + KCl 20 mEq @ 30 mL/kg/day
Normal K+ levels are 3.5-5.0 mEq/L, patient is hypoKalemic
to correct the hypokalemia along with the KCL tabs
30 mL/kg/day –> CARDIAC PATIENT (CHF)
What Fluid & how much for this patient?
NPO Patient for an elective procedure
D5W/0.45% NaCl @ 35 mL/kg/day
not an EMERGENCY / sudden surgery, likely no blood loss
need to add calories?
replace free water &insensible water losses
35 because euvolemic (normal volume)
Assessment of TOXICITY
- *FLUIDs = DRUGS**
- *volume overload is a COMMON PROBLEM**
- if not MONITORED properly*:
Monitor:
Daily weight / Labs / Physical Exam
S/Sx:
Pulmonary + Peripheral Edema // Heart Failure
↓serum Osm // ↓Na+
reduction of pOsm, means EXCESS water
↓ pOsm
IMPLIES WHAT?
(osmolarity, qualitative measure of TBW)
EXCESS OF WATER
can be HYPERvolemic
↑ pOsm
IMPLIES WHAT?
(osmolarity, qualitative measure of TBW)
LACK OF WATER
HypoVolemic
Use for COLLOID Solutions
5% Albumin // 25 % Albumin
no intracellular movement
for INTRAVASCULAR VOLUME EXPANSION
4x GREATER
IVF expansion vs equal volume of crystaloid
BLOOD TRANSFUSIONS
packed RBC’s = PRBC
- *Colloid Solutions**
- *Albumin Uses**
5% is adminstered in 250mL doses
25% is admin in 50-100mL doses
25% is DIFFERENT because
fluid flows from ISF (negative) –> IVF
interstitial –> intravascular
