IV Fluids Flashcards
Body Fluid Distribution
Intracellular 40% (2/3) total body weight 28L
Extracellular 20% (1/3) total body weight 14L
Average weight 70kg
Total 42L
Extracellular
20% total body weight 14L
Plasma volume 4% 3L
Interstitial volume 16% 11L
↑ Total Body Water
Term infants 75%
Premature infants 80-90%
Children
Pregnancy
↓ Total Body Water
Elderly 50-55%
Obesity
Average TBW
70kg adult male 60% = 42L
70kg adult female 55%
Intracellular Electrolytes
Potassium K+
Magnesium Mg2+
Phosphate PO34¯
Extracellular Electrolytes
Sodium Na+
Chloride Cl¯
Bicarbonate HCO3¯
Calcium Ca2+
Osmolality
Number osmotically active particles per kg H2O
Osmolarity
Number osmotically active particle per L solution
Concentration
Tonicity
Measures particles capable to exert an osmotic force (pull)
Isotonic
Two solutions w/ = osmolarity
No osmotic pressure generated across the cell membrane
Hypotonic
Solution w/ ↓osmolarity as compared to plasma
→ cells swell
Hypertonic
Solution w/ ↑osmolarity as compared to plasma
→ cells shrink
Starling Forces
Pc - capillary hydrostatic pressure
Pt - tissue hydrostatic pressure
πc - capillary plasma oncotic pressure
πt - tissue fluid oncotic pressure
Colloid Oncotic Pressure
Osmotic pressure exerted by macromolecules (Albumin, proteins, gamma globulins)
Prevents fluids from leaving plasma & exerts pull from interstitial space
Endothelial Glycocalyx
Gel layer in capillary epithelium that creates physiologically active barrier w/in vascular space (keeps fluid intravascular)
Creates barrier b/w blood & vessel
Binds to circulating plasma albumin, preserving oncotic pressure, & ↓capillary permeability to H2O
Contains inflammatory mediators, free radial scavenging, activates anticoagulation factors
Promotes laminar flow (prevents adhesion)
RAAS Impact on Fluid Dynamics
Sodium & water reabsorption
ACEi/ARBs ↓fluid volume
ADH
Anti-diuretic hormone
Prevents diuresis
Water reabsorption
Atrial Natriuretic Peptide
ANP
Natriuresis - sodium excretion
Stimulates kidney to release Na+ & H2O
↓intravascular volume
Crystalloid Volume Expansion
3-4L to expand IV compartment 1L
3:1 replacement
Half-life 20-30min intravascular
Normal Plasma Concentrations
Na+ 142mEq/L K+ 4mEq/L Cl¯ 103mEq/L PO43¯ 1.4mEq/L Mg2+ 2mEq/L Ca2+ 5mEq/L pH 7.4 290mOsm/L
Lactated Ringer
Buffer = lactate (converted to bicarbonate)
Isotonic (275mOsm/L)
Provides 100mL free H2O per L solution
Lowers Na+
Avoid in ESRD (K+)
Avoid mixing w/ PRBC (Ca2+ binds to citrate)
- Citrate keeps blood anticoagulated
LR Electrolytes
Na+ 130mEq/L K+ 4mEq/L Cl¯ 110mEq/L Ca2+ 3mEq/L Lactate 28mEq/L 275mOsm/L
Normal Saline
0.9% NaCl in H2O Isotonic solution ↑Cl¯ → dilutional hyperchloremic metabolic acidosis Preferred solution to dilute PRBCs LEAST physiologic isotonic crystalloid
NS Electrolyes
Na+ 154mEq/L
Cl¯ 154mEq/L
pH 6
310mOsm/L
Normosol-R
Isotonic solution Expensive \$\$$ Most closely replicates physiologic electrolytes Ideal fluid in neuro patients Okay to mix w/ blood products
Normosol-R Electrolytes
Na+ 140mEq/L K+ 5mEq/L Cl¯ 98mEq/L Mg2+ 3mEq/L Ca2+ 0 Glucose 0 Acetate 27mEq/L Gluconate 23mEq/L pH 7.4
D5W
Hypotonic solution (260mOsm/L) Dextrose rapidly metabolized → only H2O remains Causes free water intoxication & hyponatremia Hyperglycemia (except diabetic receiving insulin or neonate)
Hypertonic Solutions
3% Na+/Cl¯ 513mEq
5% Na+/Cl¯ 856mEq
Bullet 23.4% imminent herniation
Treat hyponatremia
Low volume resuscitation, burns, closed head trauma
Risk hyperchloremia, hypernatremia, & cellular dehydration
Colloid Solutions
1:1 replacement
Half-life 16hrs
2-3hrs in pathophysiological stress
Goal to pull fluid into intravascular space
Albumin
Blood derived colloid solution Obtained from fractionated human plasma Available 5% or 25% Expands IV up to 5x administered volume Plasma 1/2 life 16hrs
Dextran
Water-soluble glucose polymers
Enzymatically degraded to glucose
70 - volume expansion
40 - improve microcirculation blood flow & prevent thrombosis
HIGHLY antigenic → anaphylactic reaction
Test dose 10mL
Platelet inhibition, non-cardiac pulmonary edema, interference w/ cross-matching
Hydroxyethyl Starch 6%
Hespan (0.95% NaCl) Hextend (balanced electrolyte solution) NOT blood derivative Less effective than albumin to expand volume, but less expensive Primary renal excretion Coagulopathy d/t dilutional thrombocytopenia Max dose <20mL/kg/day Oncotic pressure 30
Maintenance IV Fluids
MIVF 4-2-1
4mL/kg/hr 1st 10kg = 40mL/hr
2mL/kg/hr 2nd 10kg = 20mL/hr
1mL/kg/hr each additional kg
Any patient >20kg
Weight + 40 = mL/hr
120kg + 40 = 160mL/hr
Fluid Deficit Replacement
NPO replacement
Replace 1/2 deficit 1st hour + MIVF
Replace 1/4 deficit 2nd hour + MIVF
Remaining 1/4 deficit 3rd hour + MIVF
Fluid Deficit Calculation
Calculated MIVF x hours NPO 120kg NPO 12hr 160mL/hr x 12hr = 1,920mL 960mL replace 1st hour 480mL replace 2nd & 3rd hours
Evaporative 3rd Space Loss
Minimal 0-2mL/kg/hr
Moderate 3-5mL/kg/hr
Severe 6-9mL/kg/hr
Emergency 10-12mL/kg/hr
Minimal
Eye, lap chole, hernia, knee scope
0-2mL/kg/hr
Moderate
Open chole or appendectomy
3-5mL/kg/hr
Severe
Bowel surgery
Total hip replacement
6-9mL/kg/hr
Emergency
Gunshot
MVA
10-12mL/kg/hr
Estimated Blood Loss
1 gram = 1cc Soaked 4x4 gauze = 10cc Ray-tech = 10-20cc Soaked laparotomy pads = 100-150cc Wet sponges 20-30% dry value Floor spills 1" = 5cc 2" = 20cc 3" = 45cc 4" = 80cc 1:1 replacement
Estimated Blood Volume
Infants 80mL/kg Children 75mL/kg Adult male 75mL/kg Adult female 65mL/kg Elderly M 65mL/kg Elderly F 60mL/kg
Allowable Blood Loss
[EBV x (starting Hct - allowable Hct)] / starting Hct
Blood Type Specific
ABO-Rh typing
98% compatible
Type + Screen
ABO-Rh type + screen
Specific antibodies commonly associated w/ non-ABO hemolytic reactions
99.94% compatible
Type + Crossmatch
Confirms ABO-Rh typing (<5min)
Detects antibodies to other blood groups & in low titers (up to 45min)
When to Transfuse
Hgb <6g/dL
Hgb 6-10g/dL transfusion based on patient risk, complications, and inadequate oxygenation S/S
Massive Transfusion
Replace patient total blood volume in <24hr
Acute admin >1/2 patient EBV in 3hr or less
Transfusion 10units RBCs in 24hr
Blood Product Administration Risk
Infection - Hep B/C, HIV, bacterial sepsis
Allergic or febrile reactions
TRALI or non-cardiogenic pulmonary edema
Hemolytic reactions
Acute hypotension transfusion reaction
Metabolic complications ↓pH ↑K+
Coagulopathy (after massive transfusion >10units)
Dilutional thrombocytopenia (responds well to platelet transfusion)
↓Factors V/VIII
DIC - clotting system activation
Citrate toxicity
Citrate
Preservative that acts as anticoagulant in stored blood
Binds to Ca2+
Calcium admin not warranted unless iCal low
Hypocalcemia (clinically significant - resulting in cardiac depression) does not occur unless transfusion rate exceeds 1 unit every 5min
PRBCs
1 unit ↑Hgb 1g/dL & Hct 2-3%
10mL/kg transfusion ↑Hgb 3g/dL & Hct 10%
Autologous Transfusion Complications
Anemia Preop MI d/t anemia Administering wrong unit Require more frequent blood transfusion Febrile & allergic reaction
Cell-Saver
Salvage blood from surgical site
Blood processed - washed & separated
Red cells are transfused back to patient
Contraindications include malignancy, infected wounds, sepsis, chemical contaminants
Acute Normovolemic Hemodilution
Remove blood from patient after induction & replace w/ crystalloid or colloids
After surgical blood loss has slowed or stopped transfuse blood back to patient ↑Hct
Platelets
1 unit obtain via centrifuging
Used to treat thrombocytopenia, dysfunctional platelets, active bleeding, platelet count <50,000
Volume 200-400cc (multiple donors)
1 unit ↑platelet count 7,000-10,000 one hour after transfusion
↑incidence platelet related sepsis 1:12,000
Bacterial contamination risk 1:2,000
Fresh Frozen Plasma
Contains clotting factors & plasma proteins (no platelets)
Volume 200-250cc
ABO compatible
Used to treat Warfarin reversal, coagulation factor deficiencies, correct microvascular bleeding ↑PT/PTT
Each unit ↑clotting factor level 2-3%
FFP contraindicated to augment plasma volume or albumin concentration
Cryoprecipitate
Derived from precipitate remaining after FFP thawed
Contains fibrinogen, factor VIII (hemophilia A), von Willebrand factor, XIII
Used to treat von Willebrand’s disease & fibrinogen deficiencies (i.e. massive transfusions)
ABO compatible
Admin via filter rapidly (200mL/hr) & complete infusion w/in 6hr
