Tobias Chapter 5 - Fluid Therapy Flashcards
What is roughly the normal distribution of water between body compartments?
What constitutes 60% total body weight in non-obese animals
Intercellular compartment accounts for 2/3 of body water and 40% of bodyweight
The remaining 1/3 of fluid is extra cellular, divided into plasma (25%) and interstitial fluid (75%)
What is the composition and function of the glycocalix?
The capillary membrane is composed of endothelial cells and a subendothelial matrix that separates the intravascular space from the interstitial space. An integral part of the endothelial barrier is a layer of glycoproteins and proteoglycans produced by the endothelium called the glycocalyx. The glycocalyx has a net negative charge that modulates its interactions with plasma components. The negative charge of the glycocalyx mesh acts as a sieve that modulates its permeability.
Discuss the link between systemic inflammatory disease syndrome (SIRS) and the development of non-pitting edema
SIRS is associated with the release of cytokines, including TNF – alpha, and bacterial lipopolysaccharide, which lead to vasodilation and increased vascular permeability. Furthermore, these cytokines lead to damage to the glycocalix, leading to the loss of protein and isotonic fluid to the interstitial space. Clinically, these animals tend to be volume depleted yet continue to lose fluid to the interstitial space.
What are the three factors that determine stroke volume?
Preload, contractility, afterload
What is the link between volume depletion and osmotic/electrolyte derangements in critically ill patients?
Volume depletion negatively affect cardiac output (SV+HR+MAP+SVR), leading to insufficient oxygen delivery to tissues. Hypoxia the metabolism from aerobic to anaerobic, leading to an energy deficient state. This affects NA/K - ATPase dependent pumps, leading to electrolyte and osmatic imbalances.
What are the current recommendations regarding fluid resuscitation in Septic patients? Give some of the main parameters and a timeline you would try to achieve to improve survival.
A protocol approach has been shown to improve survival. The goals are to achieve certain parameters within six hours of diagnosis. These include:
MAP > 65 mmHg
UOP > 0.5 ml/kg/hr
SpO2 > 95%
Htc > 30%
From a diagnostic and the therapeutic point of view, what are the priorities in a Septic patient?
Within the first hour:
Start intravenous broad spectrum antibiotic
Start aggressive IV fluid therapy
Start norepinephrine as first choice vasopressor after volume correction with crystalloids
.
Within the first six hours:
Obtain sample for culture and sensitivity
What is the definition of balanced versus unbalanced IV fluids?
Balanced IV fluids contain electrolyte concentrations similar to that of the extracellular space. Isotonic crystalloids are typically balanced.
What are the sodium and potassium concentrations in lactated ringers versus sodium chloride?
NaCl: Na 154 mEq/L
LRS: Na 130 mEq/L / K 4 mEq/L
What is the purpose of lactate in LRS?
Lactate, much like acetate, or Gluconate are bicarbonate precursors. They are metabolized in the liver ((primarily)) as well as muscles and kidneys, leading to the consumption of hydrogen in the release of bicarbonate
What IV fluid would you choose for a patient that is in metabolic alkalosis, hypochloremic and hyponatremic? Why?
NaCl
The higher concentration of sodium (154 mEq/L) and Cl (154 mEq/L) Will contribute to correcting the electrolyte abnormalities. The lack of an alkalizing agent, such as lactate, we have a tendency to correct the alkalosis as well.
What can be expected to happen with IV fluids administered within 30 minutes?
75% will distribute to the extravascular space, becoming“extracellular expanding fluids”
25% will remain intravascular
What IV fluid would you choose for a head trauma patient? Why?
Sodium chloride 0.9%
This IV fluid has the highest concentration of sodium (154 mEq/L) and will contribute to reducing the chance of cerebral edema by increasing the extra cellular osmolality.
What IV fluid would you choose for a severely hyponatremic or hypernatremic patient? Why
Choose the IV fluid the most closely matches the patient’s current sodium levels. Aim to correct sodium concentration by no more than 10 mEq/kg/day to avoid myelinolysis.
Patients in severe metabolic acidosis will benefit from IV fluids with bicarbonate precursors such as acetate due to its alkalizing effect. These fluids, however, have been associated with a decrease in blood pressure in hypovolemic patients. What is the mechanism for this response?
Acetate is metabolized in muscle into adenosine, which is a vasodilator
