Exam 3- IV Fluid Flashcards
Does overnight fasting have a significant reduce IV volume?
NO
Anesthesia related factors causing IV volume derangements (2)
- Anesthetics
2. Sympathetic blockade during neuralgia anesthesia
Surgery related factors causing IV volume derangements (6)
- Hemorrhage
- Coagulopathy due to hemodilution and hypothermia
- Decrease venous return
- Mechanical ventilation maneuvers
- Prolonged operative time, open abdominal cavity, bowel edema
- Reasons preventing transition from IV to oral fluid therapy within 24 hrs of surgery
Tissue edema effects, increase extra vascular fluid
Hypervolemia
Can hypovolemia and hypervolemia lead to tissue perfusion?
YES
3 limitations for monitoring IV volume status:
- CVP
- Urine output
- Mixed venous and oxygen saturation
What is tonicity:
Effective osmolality
What does serum sodium reflect?
Total body water status
What does sodium content in intravenous fluid dictate?
Fluid distribution
What can all crystalloids be viewed as?
Water and saline equivalents
More or less water as we age?
Less water
Increased ECF or ICF with malnutrition?
ECF
Water represents how much of weight?
50-60%
ICF:ECF ratio?
2:1
ECF is comprised of:
Interstitial fluid (3 parts) Plasma (IV) (1 part)
ISF:plasma ratio
3:1
Cellular membrane permeable to what?
Water but not ions
Principle ions of ECF:
Na+ Cl-
Principle ions of ICF:
K+ PO42-
Fluid components of blood within vessels maintained by the inward pull of…
Colloid osmotic pressure (oncotic pressure)
Fluid components of blood within vessels maintained by the outward pull of…
Hydrostatic pressure which pushes plasma out of vessels
What is endothelial glycocalyx?
Endothelium coated on luminal side with fragile glycocalyx layer
Web of membrane bound glycoproteins and proteoglycans
Glycocalyx layer
What does endothelial glycocalyx do?
First barrier to regulating cellular and macromolecule transport
What kind of pressure does endothelial glycocalyx produce?
Colloid oncotic pressure which is important to transcapillary flow
4 factors that degrade endothelium?
- Ischemia/reperfusion
- Hypoxia
- Inflammatory cytokines
- Atrial natriuretic peptide
3 protective factors of endothelium
- Sevo
- Hydrocortisone
- Antithrombin
Which ion is the primary determinant of osmolality?
Sodium
What governs IV fluid distribution within the body?
Sodium content of intravenous fluids
Represent particles which are confined to one side of the membrane thereby influencing distribution of fluids within the body
Effective osmoles
Does effective osmoles influence distribution of fluids within body?
YES
What are the 4 effective osmoles?
Glucose
Sodium
Mannitol
Glycerin
Represent particles which readily cross the membrane reaching equilibrium
Ineffective osmoles
Do ineffective influence the distribution of fluids within the body?
NO
3 examples of ineffective osmoles?
Urea
Ethanol
Methanol
Total body osmolality equation (2)
(Extracellular solute+intracellular solute)/total body water
((Nax2)+(Kx2))/total body water
Aqueous solutions of low molecular salts
Crystalloids
What dictates how crystalloids distribute?
Sodium content
Plasma sodium?
140
0.9% NaCl is?
154 mEq/L
What is normal saline?
.9% NaCl
What does each liter of .45% NaCl provide?
500ml of .9% NaCl
500ml free water
Hypertonic saline solution
3% and 5%
Provides significant salt load in a small water volume
Hypertonic saline solution
Decrease cell volume
Hypertonic saline
What does LR contain?
Sodium; isotonic
3 main types of colloids:
- Albumin
- Hetastarch
- Dextrans
What are colloids prepared in?
.9% NaCl
Albumin is an important source of what pressure?
Capillary oncotic pressure
Effectively draws interstitial fluid, if available, into vascular space
Hyperoncotic albumin
Not a protein so contribution to capillary oncotic pressure is difficult to measure and derived from amylopectin and is a synthetic glycogen like compound
Hydroxyethyl starches (HES)
What are products with high ratios expected to be?
Degraded more slowly
Does osmotic effectiveness depend on number of particles or molecular size?
Number of particles, NOT SIZE
4 adverse effects with HES:
- Increased amylase
- ESR
- Renal function
- Prolonged PT, aPTT
Moderate platelet function and are anti-thrombotic
Rheological properties
What has rheological properties?
Dextrans
How does water distribute?
From vascular compartment into interstitial space and then across cell membrane
How does sodium distribute?
Readily across capillary membrane into interstitial fluid, but it is pumped out of the cell
How do colloids distribute?
Don’t readily cross the capillary membrane. Normally confined to vascular compartment early on
3 reasons for crystalloids:
- Provide maintenance requirements
- Replacement of losses (water, blood, secretions, suction)
- Treatment of excess or deficit of fluid or electrolytes
2 things about colloids:
- Add to oncotic pressure
2. Rheological properties
Body is able to maintain water and electrolyte balance through where?
Kidneys and GI tract
What is sensible water losses?
Measurable
-kidney, GI
What are insensible water losses?
Not measurable
-respiration, fever, evaporation
Maintenance for adult?
2-2.5 L/day
Maintenance fluid rule?
4-2-1
Add 40ml to their weight (kg) if above 20kg
5 situations for increases loss:
- Fever
- Sweat
- Gastric losses (NG tube)
- Small intestine, biliary, pancreatic
- Colon (diarrhea)
Intra-op IV electrolyte crystalloid solution management and administration rate?
LR
1.5:1 volume basis until transfusion threshold met
What to avoid in intra-op IV volume management:
Dextrose
Large amount of NS .9%NaCl
What are large amounts of NS .9%NaCl associated with:
- Hyperchloremic acidosis
2. Risk of acute kidney injury
Minimal evaporative fluid losses:
0-2 ml/kg
Moderate evaporative fluid losses:
2-4 ml/kg
Severe evaporative fluid losses:
4-8 ml/kg
When is zero balance approach used?
Only fluid lost is replaced
What is recommended in major invasive surgeries?
Restrictive, zero balance approach
5 restrictive favored outcome:
- Pneumonia
- Pulmonary edema
- First bowel activity
- LOS
- Morality
3 goal directed tools:
- Pulmonary artery catheter
- Esophageal Doppler
- Preload responsiveness