Introduction to Ventilator Graphics Flashcards
Advantages of graphing
- allow view of machine-patient interaction
- troubleshooting before trouble
- identify pathophysiological changes
Basics of graphing
- machines display real time view of patient’s pressure, flow and volume
- scalar graph
- six basic shapes of scalar
- loops
What are the four flow patterns?
- square
- decelerating
- accelerating
- sine
True/false: no matter the flow pattern, the area under the curve must be equal for each pattern.
true
The relationship of pressure, flow, volume and time is based on what?
- VT = flow x Ti
- flow depends upon pressure gradient between machine and inside lungs
- flow = VT/ Ti
- pressure created depends upon the patient’s compliance and airway resistance
Volume ventilation (with constant flow)
- high driving force
- high internal resistor inside - lowers pressure
- high driving pressure ensures delivery
Normal VT breath
500 mL
Normal compliance
100 mL/cmH2O
What can’t you do if a patient is breathing?
an inspiratory pause. must wait until flow is 0.
What is the power source to a patient’s lungs and what must it be?
pressure gradient; must be super high
Volume curve
- no plateau
- no rest period
- active expiration is much longer
- amount of exhalation time is same
- expiratory flow decreases
How do you tell if someone is in PSV or PCV?
look at itime. PCV will have a set itime when PSV does not
What mode is considered a stand alone mode?
PSV
PCV
- pressure wave is constant
- pressure wave not affected by C or R
- flow varies, C changes in lung characteristics, set pressure and inspiratory effort
- flow wave rises rapidly at beginning and then decreased during insp
What happens if you decrease the support level?
machine work goes down and patient work level goes up
What is rise time?
how many milliseconds do I have to reach my goal.
What do you do to rise time if you need to get to your goal faster?
decrease it
What do you do to rise time if it takes longer to get to goal?
increase it
How to tell if active expiration?
- look at patient and see if breathing back
- huge dip in expiratory flow
- shorten itime
How to tell if active inspiration?
look at the patient to see if breathing on own
What does bronchospasm in PCV cause?
- decrease in flow
- less VT
What should you do if a patient is holding his breath? (flow is 0 but volume is staying)
shorten itime by making it 25% of peak
Does flow increase or decrease with higher resistance?
decrease; takes longer to fill up
What creates flow?
pressure gradient
