Fluid Therapy And Replacement Flashcards
4 things that rate depends on:
- Permeability of substance
- Concentration differences
- Pressure differences
- Electrical potential
Net movement of water across a semipermeable membrane due to a difference in solute concentrations
Osmosis
Number of osmoles/liter
Osmolarity
Number of osmoles/kilogram of water
Osmolality
Normal human serum osmolality
275-299 miliosmoles/kilogram
Total body water
60% of body weight, 42L
Intracellular fluid
67% of TBW, 28L
Extracellular fluid
33% of TBW, 14L
Interstitial fluid
25% of TBW, 11L
Plasma fluid (intravascular)
8% of TBW, 3L
Volume of water in males
60%
Volume of water in females
50-55%
Volume of water in newborns
75%
Volume of water in obese patients
As low as 45%
Intracellular fluid body compartment (4)
- Comprises 2/3 of TBW
- Osmotic pressure determined by K+
- High protein content
- Controlled by ATP pump
Extracellular fluid body compartment (3)
- Comprises 1/3 of TBW
- Osmotic pressure determined by Na+
- Subdivided into interstitial and intravascular (plasma)
Interstitial extracellular fluid compartment (2)
- Very little free fluid
2. Reservoir for intravascular compartment
Intravascular extracellular fluid compartment (3)
- Restricted by vascular endothelium
- Electrolytes pass freely
- Plasma proteins usable to pass (albumin)
Crystalloids (3)
- Aqueous solutions of ions (glucose)
- IV half life is only 20-30min
- Large volumes cause edema
Movement of water in hypotonic fluids
Water will move intracellularly
-decreases IV volume
Hypotonic fluids osmolarity
<240 MOSM/L
Uses of hypotonic fluids (3)
- Hypernatremia
- Diabetic ketoacidosis
- Hyperosmlar/hyperglycemia
4 risks of hypotonic fluids
- Increase ICP
- Worsens hypotension
- Hyperglycemia
- Hemolysis
Water movement of hypertonic fluids
Mostly remains in ECF
-pulls from ICF
Osmolarity of hypertonic fluid
> 310 MOSM/L
2 uses for hypertonic fluid
- Plasma expanders
2. Reduce cerebral edema
4 risks of hypertonic fluids
- Hyperchloremic metabolic acidosis
- Pulmonary edema
- IV infiltration
- Cellular dehydration
Serum osmolality of isotonic fluids
275-299 MOSM/KG
Use of isotonic fluids
Replace extracellular volume
Risk of isotonic fluids
Fluid overload (caution in cardiac/renal pts)
2 things that lactated ringers has:
Potassium and calcium
3 cautions with lactated ringers
- Renal pts
- Hyperkalemia pts
- Do NOT use with blood administration
Osmolarity of normal saline
308 MOSM/KG
When is normal saline preferred?
Renal pts
Brain injury
Blood administration
What can large volumes of normal saline cause?
Hyperchloremic metabolic acidosis
What does colloids contain?
Proteins and large glucose polymers
Intravascular half life of colloids
3-6hrs
Two types of albumin
5% (iso-oncotic)
25% (hyper-oncotic)
How long do effects of albumin last?
16-24hrs
What 2 types of dextran’s are there?
Dextran 70 (macrodex): molecular wt 70,000 Dextran 40 (rheomacrodex): molecular wt 40,000
3 complications of dextran:
- Anti platelet effects
- Acute kidney injury
- Anaphylactic rxns
Synthetic colloid derived from natural polysaccharides
Hydroxyethyl starches (HES)
Duration of volume with hydroxyethyl starches
2-5hrs
3 complications with hydroxyethyl starches
- Pruritus from tissue storage
- Coagulopathy
- Renal toxicity
4 signs of laboratory analysis
- Increasing HCT/HB
- Hypernatremia
- BUN: CR ratio > 10:1
- Progressive metabolic acidosis
7 signs of intraop hypovolemia
- Tachycardia
- Poor urine output
- Decreased BP
- Wavering pulse ox
- Arterial line respiratory variation
- Hypernatremia
- Decreased CVP
5 signs of intraop hypervolemia
- Rales
- Frothy secretions
- Hyponatremia
- Polyuria
- Peripheral edema
- BP
- HR
- Urine Output
- Central Venous Pressure (CVP)
- Mixed venous oxygen saturation
Static parameters
- Respiratory variation
- SV
- L ventricular size
Dynamic parameters
CVP RA normal pressure
2-7mmHg
SVV equation
SVmax-SVmin/SVmean
Normal SVV
10-15%
PPV equation
PPmax-PPmin/PPmean
Normal PPV
10-15%
What SVV or PPV suggests that pts may be responsive to fluid therapy?
> 15%
Arterial pressure tracing estimates:
CO
PP
SV variation with ventilation
2 ways to perform L ventricular size:
Transesophageal echocardiography (TEE) Transthoracic echocardiography (TTE)
TEE
Invasive
Better visualization
TTE
Less invasive
Visualization harder
Daily maintenance requirements
2500ml/day
4 replaces fluids
- Maintenance requirements
- Deficits
- Estimated Blood loss
- Other surgical fluid losses
4-2-1
First 10kg - 4ml/kg/hr
Next 10kg - 2ml/kg/hr
Each kg above 20 - 1ml/kg/hr
Bowel prep deficit
500ml
4x4 sponges holds blood loss
10ml
Laparotomy pads (laps) holds blood loss
100-150ml
Replacement of EBL:crystalloid
1:3
Replacement of EBL:colloid
1:1
Surgical evaporative loses minimal
2-4 ml/kg/hr
Surgical evaporative loses moderate
4-6 ml/kg/hr
Surgical evaporative loses severe
6-8 ml/kg/hr
Internal redistribution of fluid leading to fluid shifts and loss of IV fluid
3rd space fluid loss
Replacement of preexisting fluid deficits over 3 hr
1/2 deficit in 1st hr
1/4 deficit in 2nd hr
1/4 deficit in 3rd hr