Fluid 1 Flashcards
Definition of fluid
any material that has the ability to flow, when placed in a container the take the shape of the container
Solubility
is the maximum amount of one substance (solute that is able to dissolve into another (solvent)
What factors effect solbility
intermolecular interactions between the substances, temperature, and pressure
Pressure exerts little to no influence on solubility of solids and liquids. But gas solubility in a liquid is directly proportional to pressure and part of Henry’s Law
Why do solvents and solute mix?
the have similar electron configurations, H2o and salt have similar polarity
Endothermic reaction
Solubility is increased with increased temperature
it requires more energy than it produces, it consumes heat rather than produces heat.
Exothermic
energy is released in excess of the energy required to break the bonds of the solute
Explain the solubility of Gases
Gas solubility in liquids is inversely related to temperature.
As temperature increases, less gas is able to
dissolve into the liquid.
An increased temperature represents greater
kinetic energy. Greater kinetic energy allows
dissolved gas molecules to escape and prevents
further dissolving.
Lower temperature slows the kinetic energy of gas molecules, allowing them to dissolve into liquids
A clinical example of temperature affecting
solubility is seen with the slower emergence of
hypothermic patients receiving volatile‐agent
general anesthesia.
The hypothermic patient retains anesthetic gases in the blood due to increased solubility related to temperature.
Gas solubility in a liquid is directly proportional to pressure AKA Henry’s Law
Salt disolved in water
Gas dissolved in water,
What happen when we increase the temp?
Solubility of salt increases with temp.
Solubility of gas decreases with temp
LeChatelier’s principle applies to both- IT predicts the effect of a change in conditions on chemical equilibrium
what effect does hypothermia have on gas solubility
as a liquid is cooled, more gas dissolves in the liquid therefore, hypothermia will cause an increase in gas solubility
Ostwald Solubility coefficient
After an anesthetic is allowed to equilibrate between an equal volume of gas and blood, λ = the amount of anesthetic in the blood phase divided by the amount of anesthetic in
the gas phase
The higher the blood:gas partition coefficient(also called Ostwald Solubility Coefficient), the longer it takes to induce
anesthesia and the longer it takes to emerge from anesthesia.
The agent follows a series of partial pressure gradients to reach its target, the brain:
delivered > inspired > alveolar > arterial> brain & tissue
The Ostwald solubility coefficient is a measure of what?
it is a measure of the solubility of a gas in a fluid
- It is the ratio of the concentration of gas dissolved in solution to the concentration of gas in the gas phase at equilibrium at 37C
- Blood-gas partition coefficient of inhalational anesthetics are derived from Ostwald solubilites
Henry’s Law
“at constant temperature, the amount
of gas dissolved in a liquid is directly proportional to the partial pressure of that gas at equilibrium above the gasliquid interface”
p = k * c
Where p is the partial pressure of the solute above the solution, k is Henry’s constant, and c is the concentration of the solute in the solution
increased delivery of oxygen (FiO2) to patients to improve arterial oxygenation (PaO2) and overpressuring (high concentration) anesthetics reflect the direct relationship of pressure and solubility described by Henry’s Law.
Increasing the partial pressure of a gas above a liquid will increase the amount of gas that dissolves in the liquid.
Henry’s law states that the amount of a gas that dissolves in a liquid is proportional to the partial pressure of the gas in the gas phase.
The main applications of Henry’s law in anesthesia pertains to calculating how much O2 dissolves in blood and how much CO2 dissolves in blood.
What is over pressuring
is the process of significantly increasing
a volatile anesthetic concentration (partial pressure) delivered to a patient to increase the alveolar concentration, and therefore the amount dissolved in the blood, to speed uptake.
Blood gas partition coefficient
desflurane has a small/gas partition coefficient
older ones have a high coefficient which means large amounts will need to be taken up, in the body to be passed on to the fatty tissues of the brain where it can exert its effect.
