Perioperative Crystalloid and Colloid Therapy

T/F: Crystalloid and Colloid fluids are drugs

True

T.B.W = __% of body weight

60%

Which has more T.B.W neonates or older patients?

Neonates

T.B.W needs to established based off of ___ weight, why is this important?

• Lean

  • Fat can disrupt this calculation, making the T.B.W seem higher than it is

What % of TBW is plasma?

5%

What makes up the majority of TBW?

• ICF (40% of BW)

• ECF (20%)

  • Interstitial Fluid (15%)

  • Plasma (5%)

A key principle of body fluids is permeability, what is the difference between the permeability of the capillary endothelium and the cell membrane?

• Cell Membrane

  • Freely permeable → H20

• Capillary endothelium (more “controlling“)

  • Freely permeable → H2O and various ionic solute

  • Limits proteins, large MW, and negatively charged molecules

The movement of H2O between ICF and ECF is governed by the ______ gradient, what is this gradient?

• Osmotic gradient

  • The difference in solute concentrations across membranes (hypertonic/hypotonic)

What is the difference between an effective osmole and an ineffective osmole?

• Effective

  • Contributes to osmolarity/fluid shifts, cannot cross cell membrane

• Ineffective

  • Can cross cell membrane (ex Urea)

What is Starlings Principle?

• It describes the movement of fluid across capillary walls as a function of

  • Hydrostatic pressure and Osmotic pressure

In the vasculature, osmotic pressure is largely drive/controlled by what protein?

ALBUMIN

What is the goal of fluid therapy?

Preserve tissue perfusion by maintaining or restoring effective circulating intravascular volume (maintaining O2 deliver to tissues)

T/F: IV fluids can only serve to benefit the patients

False, its a Drug, it can benefit or harm depending on dose, administration and correct/appropriate usage

The 2 general categories of perioperative fluids are? What’s the difference between the two?

1. Crystalloid

   1. Crystalloids (e.g., Normal Saline, Lactated Ringer's) are small-molecule solutions used for initial resuscitation, dehydration, and maintenance fluids

   2. Distributing widely in the body but requiring 3:1 (volume:loss) replacement.

2. Colloids

   1. Colloids (e.g., Albumin, FFP) contain large molecules that stay in the intravascular space

   2. Offering faster, 1:1 volume expansion but carrying higher risks of allergic reactions, renal damage, and costs

What are the 2 types of Crystalloids? Describe each, which is the fluid of choice for anesthesia?

1. Isotonic

   1. Osmolality = Plasma

   2. No change to the solute of plasma

   3. Redistributes to ECF after 30-60 minutes → Expands the ECF

2. Hypertonic

   1. Osmolality > Plasma

   2. Increases solute of plasma, pulls water from the ICF (Intra-cellular) and ISF (interstitial)

      1. Expands plasma volume

What are the indications for the use of Isotonic and Hypertonic Crystalloids?

• Isotonic

  • Anesthesia

• Hypertonic

  • Rapid resucitation of hypovolemia

  • Cerebral edema/increased intracranial pressure

    • Bc it will pull the fluid out of ICF/ISF and into the vasculature

Hypertonic crystalloids should always be followed with isotonic fluids, why?

Bc hypertonic crystalloids can cause cellular dehydration the isotonic fluids can mitigate this

How do colloids work?

• Colloids contain large molecules that have very limited movement across the capilalry endothelium

• They pull water from the ISF → IVF (vasculature) based off of oncotic pressure (protein based)

What are the indications of Colloid fluid therapy?

• Hypoproteinemia (hypoalbuminemia)

• Hypovolemia

Remember that colloid therapy add a bunch of large molecules to increase the oncotic proterites of the IVF

What is the main example of synthetic colloids? What is its advantages/disadvantages

• HES (Hydroxyethyl starch)

  • Advantages

    • Sustained expansion of vascular compartment compared to isotonic crystalloids (longer effect)

    • Small volume required to achieve desired effect (Potent)

  • Disadvantages

    • Serious adverse effects, weigh your options before using

You should never exceed more than __ mL/kg/day of HES

20

When calculating how to use HES in your patient, you should opt for the ______ dose over the _______ time

Smallest dose over the shortest time

What are the 3 types of Natural colloids?

• They are all blood components

  1. RBC products

  2. Plasma Products

  3. Albumin Products

A 25kg dog underwent an OHE, during the procedure they accidentally dropped a pdicle and estimated that blood loss was 250 mLs, what % blood volume was lost?

• B.V = 90 mL/kg (for dogs) * 25 kg = 22550 mL

• % blood volume lost = (250/2250)*100 = 11%

Given the following question, should you administer fluids to the patient? If yes what kind?

• If <10% of blood volume is lost then you can use isotonic crystalloids for replacement

T/F: During fluid therapy once you calculated the dose the patient needs you will not need to adjust that dose during or after procedures

False, always assess and reassess your patient, you may need to adjust your dosages