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RTH 132 Hannah > How A Breath is Delivered > Flashcards

Flashcards in How A Breath is Delivered Deck (53)
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1
Q

What factors does the ventilator control?

A

Flow, volume, pressure

2
Q

What are the phases of the breath accomplished?

A

Trigger variable, limit variable, cycle variable and baseline variable

3
Q

What are the two forces that act on the respiratory system during mechanical ventilation?

A

Muscle pressure or ventilator pressure

4
Q

The amount of volume delivered depends on what?

A

Compliance and resistance to gas flow

5
Q

What is the Rhorer equation of motion?

A

Pmus + Ptr = V/C + (Raw x flow)

6
Q

What is the ventilator’s single most important function?

A

Delivery of inspiration

7
Q

A _______ is the primary variable that the ventilator manipulates to cause inspiration

A

Control variable

8
Q

What are the three choices of the control variable?

A

Volume, flow and pressure (time is implicit and can be a control variable)

9
Q

How many variables can be controlled at a time?

A

One

10
Q

What is volume control?

A

Volume is controlled, and the volume and flow waveforms are constant. Pressure varies with changes in compliance and resistance. Machine MUST measure volume when using a true volume controller

11
Q

What are other names of volume control?

A

Volume ventilation, volume targeted, volume limited

12
Q

When the ventilator keeps the _______ waveform in a specific pattern, the breath is said to be volume controlled

A

Volume

13
Q

What waveform changes during volume control?

A

Pressure (changes with compliance and resistance)

14
Q

What does it mean when one uses pressure control?

A

Pressure delivered is constant but volume and flow vary with changes in compliance and resistance

15
Q

What are other names for pressure control?

A

Pressure targeted, pressure ventilation and pressure limited

16
Q

What is the reality when it comes to pressure controlled ventilation?

A

The patient feels better but it may be more difficult

17
Q

What is happening when using flow control?

A

Flow and volume are constant while pressure varies with changes in compliance and resistance

18
Q

Any ventilator that has a set _____ waveform and a set _____ also has a set _____ waveform and vice versa

A

Flow; time; volume

19
Q

What is time control?

A

When both pressure and volume waveforms are affected by the changes in lung characteristics

20
Q

Who is time control used on?

A

Kids

21
Q

Time control is also referred to as

A

High frequency or oscillation, and is not used very frequently

22
Q

Inspiration is commonly referred to as

A

Volume or pressure controlled

23
Q

Flow, volume or pressure waveforms usually take one of four shapes

A

Rectangular (square or constant), exponential (increasing/decreasing), sinusoidal (sine) or ramp (ascending/descending)

24
Q

What is the trigger variable?

A

The start of the breath (initiation). Can be patient or machine

25
Q

What is the limit variable?

A

What is controlled during each breath (inspiration itself)

26
Q

What is the cycle variable?

A

What terminates the breath (end of the breath)

27
Q

What is the baseline variable?

A

Expiratory phase

28
Q

What is machine time trigger?

A

The ventilator begins itself by a timing mechanism (each breath is initiated by time) and is insensitive to the patient’s effort

29
Q

What should you set the rate at if using a machine time trigger?

A

10 breaths/min (one breath every 6 seconds)

30
Q

What is the patient trigger?

A

The machine senses or knows the patient wants a breath

31
Q

What is response time?

A

How fast the machine responds (usually at 0.08 seconds) and cannot be adjusted. The longer the response time the more work of breathing (time delay)

32
Q

What is sensitivity?

A

Determines the amount of effort

33
Q

What happens if you decrease sensitivity?

A

Increase in work of breathing (make it harder for the patient to breathe)

34
Q

What happens if you increase sensitivity?

A

Decrease in work of breathing (make it easier for the patient to breathe)

35
Q

What is pressure trigger assist?

A

The machine begins inspiration when the patient starts to inspire and removes a small amount of volume from the circuit, which creates negative pressure

36
Q

What is flow trigger (bias flow)?

A

A continuous supply of low level flow that is delivered (reduces work of breathing during response time)

37
Q

What must the base flow be?

A

Twice the trigger flow

38
Q

What does it mean if there is no bias flow?

A

It is a dead circuit and there is no airflow

39
Q

What does it mean if there is bias flow?

A

There is enough flow given until the breath is recognized by the machine

40
Q

What is volume trigger?

A

The machine cycles when a preset volume has been removed from the circuit

41
Q

What is manual volume trigger?

A

A manual button on the machine, that when pushed, will initiate a positive pressure breath

42
Q

What is limits of ventilation?

A

One of the four physical parameters that can be reached but not exceeded during a breath. Reaching a limit does NOT end a breath

43
Q

What is volume limited?

A

The volume reached will be held in the airway until a preset time is reached, and that time will end the breath

44
Q

What is time limited?

A

Limiting inspiration or expiration to a certain time. Cannot trigger or cycle next breath until the time has passed

45
Q

What is pressured limited?

A

Pressure is increased to a preset level at the beginning of inspiration and is held at the airway until the breath ends by either time for flow

46
Q

Why do you have the highest flow at the beginning of inspiration?

A

That is when the pressure gradient is the largest

47
Q

When is the breath cycled or ended?

A

When the machine pressure equals the pressure in the lungs (flow is 0)

48
Q

What are you guaranteeing with a pressure limit?

A

Guaranteeing a certain pressure will be applied over the breath while volume and flow vary

49
Q

What does the patient control while the machine maintains pressure?

A

Speed and tidal volume

50
Q

What is rise time (pramp)?

A

When you set how long you want to take to reach the set pressure level

51
Q

People who breathe super fast have what?

A

Low tidal volumes and super turbulent flow (i.e. status asthmaticus)

52
Q

What is flow limited?

A

When the flow reaches a constant value before the end of inspiration

53
Q

Pressure limiting vs pressure cycling

A

Pressure cycled: in order to prevent excessive pressure from going to the patient, the inspiration is ended
Pressure limited: limiting the amount of pressure that can be delivered to a patient but does not end the breath, just limits the pressure that can be applied from the ventilator