Pressure/Gases Flashcards
What is the equation to find pressure?
Force/area
mmHG is:
Millimetres of mercury (used in measuring blood pressure)
cmH20 is:
Centimetres of water (a measurement of central venous pressure)
Psi is:
Pounds per inch (direct pressure on an object)
Pressure is measured in:
Pascal (pa) 1 newton over 1 square meter
What is static liquid?
Evenly distributed pressure in all directions
What is the Bernoulli effect?
An increase in the speed of a fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluids potential energy (speed increases, pressure decreases)
How do we apply the Bernoulli effect in clinical practice?
Iv fluid - the higher the bag is, the faster the fluid will flow to the patient
When the heart relaxes, it creates:
Pressure in blood vessels (blood pressure)
What determines the resistance of blood flow?
Vessel diameter, length and blood viscosity
Constricted vessels do what to blood pressure?
Increases it and therefore reduces blood flow
Dilated vessels do what to blood pressure?
Decreases it and therefore increases blood flow
What is the gas law?
A gas is a collection of particles in constant, rapid, random motion
What is Boyles law?
The pressure of a given mass of an ideal gas is inversely proportional to its volume at a constant temperature (Pressure and volume of a gas have an inverse relationship)
As volume occupied increases, pressure
Decreases
As volume occupied decreases, pressure
Increases
What is Dalton’s law?
In a mixture of gases, the pressure is the sum of the individual gas pressures
How do we clinically apply to Dalton’s law?
Partial pressures within respirators rely on this law for safety in ensuring oxygen input and CO2 output remains stable and the gas mix is compatible with life. Or, decompression is required to equalize pressures in the body.
What is Henry’s law?
The mass of a gas that will dissolve in water at a given temperature is proportional to the partial pressure of the gas and to its solubility coefficient.
What does Henry’s law apply to?
Gas exchange, alveolar air composition, concentration gradients
What are saturation levels?
The measurement of the amount of haemoglobin molecules with oxygen attached and is an indicator of respiratory function and potential anaemia
What are nebulisers?
Pressurised gas that is used to create a Bernoulli effect inside a mask to administer fluids in droplet form
What is PaCO2?
Measurement of carbon dioxide
Carbon dioxide is carried as:
Carbonic acid (H2CO3)