Flow Flashcards
Describe conservation of energy
Total energy in a system remains constant
(No net gain or loss)
Two examples of energy changing forms while still preserving overall sum of energy?
Potential energy
Kinetic energy
Define flow
Movement of a specific volume of fluid in a specific period of time
Measurements of flow on ventilator
L/minutes
Units of measurement used for respiration
L/second
Differentiate between flow and velocity
Flow: how much volume moves over time
(Gallons per second)
Velocity: how far something travels in time
(Miles per hour)
Explain the principle of continuity for flow
The same mass of flow that enters must exist
Velocity changes with changes in tube side
How is velocity and cross-sectional area/ diameter related
Inversely related
What happens to velocity if it is equally exerted amongst multiple tubes
The velocity is equally dispersed though out each tube and overall lower
Define Bernoulli law
In a steady flow the sum of all forms of energy in fluid is the same throughout the path of flow
(Velocity and lateral wall pressure are inversely proportional)
How are velocity and lateral wall pressure proportional
(Velocity and lateral wall pressure are inversely proportional
What happens to pressure in states of high velocity
Pressure decreases to conserve the level of energy
What is the lateral pressure in the conducting airways
Lateral pressure is high
What happens to flow in the smaller airways
It slows down/ low velocity
Lateral pressure is consistent throughout
In low velocity: kinetic energy and pressure
Kinetic energy is low
Pressure is high
In high velocity: kinetic energy and pressure
Kinetic energy is high
Pressure is low
What happens to flow during exhalation
Lateral pressure is higher
Velocity is low
What kind of flow is low velocity tubes
Laminar
Inhalation creates what type of pressure to help open airways
Negative
Exhalation creates what type of pressure in the airways
Positive
What is the problem with Bernoulli’s principal
Ideal rather than real positions
Where is viscosity higher in a tube
Gasses furthest from the wall
Where does gases move slower
Closet to the wall due to friction
Where does gas have the most velocity
Velocity is highest in the center
Define driving pressure
The pressure required to drive flow proportional to viscosity
Define Reynold Number
A calculation of turbulence
What are the three forces calculated to produce (inertial force) Reynolds’s number
V= velocity
R= radius
P= density
Reynolds’s number that denotes laminar flow
<2,000
Reynolds’s number that denotes transitional flow
2,000-3,000
Reynolds’s number that denotes turbulent flow
> 3,000
What requires more pressure between laminar and turbulent flow
Turbulent flow requires significantly more pressure
Explain how the radius of a tube affects the driving pressure?
Smallest narrowing of radius increases driving pressure significantly
Relationship between flow and radius
Flow is directly proportional to radius to the fourth
Why are patients with emphysema at risk of airway collapse
Normal airways have enough structure to not succumb to positive pressure
Explain the vulnerability of airways to collapse on exhalation in COPD based on alveolar pressure and air trapping
There is more driving pressure leading to less lateral pressure holding airway walls of.
What prompts electrical voltage to move
Moves from high voltage to low voltage
Two ways to increase flow with ventri
Smaller jet
Larger port
Write out Ohm’s law
Resistance= voltage/current
Ohms =V/A (amps)
Current= voltage/resistance
What is the potential energy of electricity
Voltage
What must electricity overcome to become flow
Resistance
An example of a low resistance material for electricity
Copper wire
An example of a high resistance material for electricity
Rubber tubing.
What is resistance measured in
Ohms
What is current measured in
Amperes
How is current and resistance related
Inversely
How is current voltage related
Directly proportional
Electricity flows from hot to the neutral. What happens if the wiring is faulty?
Excess Current flows to low resistance ground
Effects of a electrical shock below 1 milliamp
Generally not perceptible
Effects of a electrical shock of 1 milliamp
Faint tingle
Effects of electrical currents of 5 milliamps
Slight shock
Not painful
Average individuals can let go
Strong involuntary reactions can lead to injuries
Effects of electrical currents to women of 6-25 milliamps
Painful shock
Loss of muscle control
Effects of electrical currents of 9 to 30 milliamps to men
Freezing current or “let go” range
If extensor muscles are stimulated a person might be thrown back
Individuals can’t let go
Effects of 50-150 milliamps
Extreme pain
Respiratory arrest
Severe muscle reaction
Death is possible
Effects of 1- 4.3 Amps
Rhythmic pumping of the heart ceases
Effects of 10 amps
Cardiac arrest
Severe burns
Death is probable
At what voltes is the skin broken and tissue exposed
500 volts
Always examine under the skin
Skin offers variable resistance. What factors influence electrical current
How clean
Chemistry of the skin
How damp
How does the ground-fault circuit interrupter outlet provide electrical safety
Monitors return of current in neutral wire
If GFCI detects drop in return it cuts off outgoing flow
How do you test GFCI test
Press “re-set”
Plug in device and see it receive power
Press “test”
Power to device should shut off
What does GFCI stand for
Ground
Fault
Circuit
Interrupter
Who in the hospital checks the devices form home for electrical safety
Respiratory therapist
What does “PASS” stand for
Pull
Aim
Squeeze
Sweep
What does “RACE” stand for
Rescue
Alarm
Contain
Extinguish
What device measures flow in a ventilator
Pneumotachometer
What is voltage synonyms with
Pressure
Formula for flow
Pressure change (p1-p2)/resistance
What units are used for flow
L/time
What is the potential energy of electricity
Voltage
What does electricity need to do to flow
Overcome resistance
What is resistance measured in
Ohms
How do you calculate amps
A=V/ohms/resistance
How is voltage and resistance proportional
Directly
Flow resistance unit for ventilator
CmH2O/L/sec
Formula for compliance
Change in V/change in P
What is the static compliance
P(E)
No flow or resistance
What pressure is the dotted line
Pressure in the alveoli
What is dynamic compliance
Calculation drawn from PIP rather than peak alveolar pressure
(Total work of delivery)
Formula for dynamic compliance
P(E)+P(R)
What is Plateau pressure
A measurement of Aw pressure
Taken after breath during pause
Under “0” flow
Before exhalation
What does the hysteresis curve represent
The lag in volume response to the changes in Aw pressure Taken after
What does the Pawo stand for
Pressure at the Aw opening
(Pressure at Aw)
What does the Pta stand for
TransAw pressure
What does crosshatche represent
Aw resistance
