1. Trigger/Limit/Cycle/Baseline
Mechanical Ventilation

2. Trigger
All breaths on a ventilator need to be triggered

3. Trigger All breaths on a ventilator need to be triggered They can be
Time triggered

4. Trigger All breaths on a ventilator need to be triggered They can be
Time triggered
Patient triggered

5. Trigger All breaths on a ventilator need to be triggered They can be
Time triggered
Patient triggered
Flow triggered

6. Trigger All breaths on a ventilator need to be triggered They can be
Time triggered
Patient triggered
Flow triggered
Pressure triggered

7. Time triggering
Time triggering means the ventilator starts the breath

8. Time triggering Time triggering means the ventilator starts the breath
This will happen when there is no patient effort

9. Time triggering Time triggering means the ventilator starts the breath
This will happen when there is no patient effort
This is based on the set respiratory rate

10. Patient Triggering
A breath can be triggered by the patient

11. Patient Triggering A breath can be triggered by the patient
Flow triggering is the most common

12. Patient Triggering A breath can be triggered by the patient
Flow triggering is the most common
Pressure triggering is another option

13. Flow Triggering Flow triggering starts with a base flow
This flow is continuously flowing through the circuit

14. Flow Triggering Flow triggering starts with a base flow
This flow is continuously flowing through the circuit
The ventilator knows how much flow is going through the circuit
The liter flow leaving the ventilator should be the same as the liter flow coming back

15. Flow Triggering
As the patient inhales some of the flow goes into the patient lungs
This means less flow is returning to the ventilator
The ventilator senses that as a patient effort and starts a breath

16. Flow Triggering
The difference in the flow coming out of the ventilator and coming back to the ventilator is how sensitivity is determined
The less flow needed to be deflected by the patient the more sensitive it is
The more flow needed to be deflected by the patient the more difficult it is to trigger, i.e. less sensitive

17. Flow Triggering 10 lpm is leaving the ventilator
10 lpm is returning to the ventilator
As a patient inhales and takes in 2 lpm
8 lpm is returning to the ventilator
This reduction in returned flow tells the ventilator to start a breath

18. Flow Triggering
If you increase the amount of flow needed to be inhaled by the patient the less sensitive the machine is
10 lpm is leaving the ventilator
10 lpm is returning to the ventilator
As a patient inhales and takes in 4 lpm
6 lpm is returning to the ventilator

19. Pressure Triggering
Negative pressure is generated when a patient inhales

20. Pressure Triggering
Negative pressure is generated when a patient inhales
This negative pressure is in both the patients lungs and the ventilator circuit

21. Pressure Triggering
Negative pressure is generated when a patient inhales
This negative pressure is in both the patients lungs and the ventilator circuit
The ventilator senses the negative pressure as a patient effort and starts a breath

22. Pressure Triggering
So the patient needs to generate -2cmH2O to start a breath
If you increase the amount of negative pressure needed the more difficult it is for the patient to trigger, i.e. less sensitive

23. Limiting
Limiting is what contols are in effect during the inspiratory phase

24. Limiting
Limiting is what contols are in effect during the inspiratory phase
After a breath is initiated certain limits will be in effect depending on which type of breath is being delivered

25. Limiting
Limiting is what contols are in effect during the inspiratory phase
After a breath is initiated certain limits will be in effect depending on which type of breath is being delivered
Limiting factors are what define a type of breath

26. Limiting
Limiting is what contols are in effect during the inspiratory phase
After a breath is initiated certain limits will be in effect depending on which type of breath is being delivered
Limiting factors are what define a type of breath
The two most common limits are

27. Limiting
Limiting is what contols are in effect during the inspiratory phase
After a breath is initiated certain limits will be in effect depending on which type of breath is being delivered
Limiting factors are what define a type of breath
The two most common limits are
Pressure

28. Limiting
Limiting is what contols are in effect during the inspiratory phase
After a breath is initiated certain limits will be in effect depending on which type of breath is being delivered
Limiting factors are what define a type of breath
The two most common limits are
Pressure
Flow

29. Pressure Limited
Pressure limited breaths have a set peak airway pressure

30. Pressure Limited
Pressure limited breaths have a set peak airway pressure
The pressure in the patients lungs will not go over the set pressure

31. Pressure Limited
Pressure limited breaths have a set peak airway pressure
The pressure in the patients lungs will not go over the set pressure
The following breaths are pressure limited

32. Pressure Limited
Pressure limited breaths have a set peak airway pressure
The pressure in the patients lungs will not go over the set pressure
The following breaths are pressure limited
PCV
PSV
PRVC

33. Pressure Limited Pressure Control Ventilation (PCV)
Pressure is set with the intention of reaching the peak pressure and holding the pressure for part of the inspiratory time

34. Pressure Limited Pressure Control Ventilation (PCV)
Pressure is set with the intention of reaching the peak pressure and holding the pressure for part of the inspiratory time
Pressure Support Ventilation (PSV)
Pressure is set to augment a patients own tidal volume

35. Pressure Limited Pressure Control Ventilation (PCV)
Pressure is set with the intention of reaching the peak pressure and holding the pressure for part of the inspiratory time
Pressure Support Ventilation (PSV)
Pressure is set to augment a patients own tidal volume
Pressure Regulated Volume Control (PRVC)
Pressure changes with each breath with the intention of reaching a specific volume

36. Flow Limited
Flow limiting is used when a specific volume needs to be delivered

37. Flow Limited
Flow limiting is used when a specific volume needs to be delivered
Each breath has a rigid flow rate and pattern that will deliver the specific volume

38. Flow Limited
Flow limiting is used when a specific volume needs to be delivered
Each breath has a rigid flow rate and pattern that will deliver the specific volume
Therefore the breath is limited to a predetermined flow
Volume Control is a type of flow limited breath

39. Pressure vs. Flow Limiting
Pressure limited breaths have a variable flow which allows better gas distribution

40. Pressure vs. Flow Limiting
Pressure limited breaths have a variable flow which allows better gas distribution
The pressure is limited therefore if lung conditions change the volume will change

41. Pressure vs. Flow Limiting
Pressure limited breaths have a variable flow which allows better gas distribution
The pressure is limited therefore if lung conditions change the volume will change
If lungs become stiffer the volume will go down as the pressure remains the same

42. Pressure vs. Flow Limiting
Flow limiting will deliver a volume no matter what the lung conditions

43. Pressure vs. Flow Limiting
Flow limiting will deliver a volume no matter what the lung conditions
Volume will be consistent but pressures will change

44. Pressure vs. Flow Limiting
Flow limiting will deliver a volume no matter what the lung conditions
Volume will be consistent but pressures will change
If the lungs become stiffer the pressures will go up

45. Pressure vs. Flow Limiting
PRVC uses pressure limiting but will automatically adjust the pressure to deliver a volume

46. Pressure vs. Flow Limiting
PRVC uses pressure limiting but will automatically adjust the pressure to deliver a volume
So the pressure is not set, the volume is set

47. Pressure vs. Flow Limiting
PRVC uses pressure limiting but will automatically adjust the pressure to deliver a volume
So the pressure is not set, the volume is set
The ventilator will adjust the pressure to achieve the volume

48. Pressure vs. Flow Limiting
PRVC uses pressure limiting but will automatically adjust the pressure to deliver a volume
So the pressure is not set, the volume is set
The ventilator will adjust the pressure to achieve the volume
This allows for the variable flow which is better for gas distribution

49. Pressure vs. Flow Limiting
PRVC uses pressure limiting but will automatically adjust the pressure to deliver a volume
So the pressure is not set, the volume is set
The ventilator will adjust the pressure to achieve the volume
This allows for the variable flow which is better for gas distribution
If the lungs become stiffer the pressures will go up

50. Cycling
Cycling is what determines how the breath will stop and allow the patient to exhale

51. Cycling
Cycling is what determines how the breath will stop and allow the patient to exhale
Most breaths are time cycled

52. Cycling
Cycling is what determines how the breath will stop and allow the patient to exhale
Most breaths are time cycled
Any breath type that requires a set Ti is time cycled
These include the following breath types

53. Cycling
Cycling is what determines how the breath will stop and allow the patient to exhale
Most breaths are time cycled
Any breath type that requires a set Ti is time cycled
These include the following breath types
PRVC

54. Cycling
Cycling is what determines how the breath will stop and allow the patient to exhale
Most breaths are time cycled
Any breath type that requires a set Ti is time cycled
These include the following breath types
PRVC
PCV

55. Cycling
Cycling is what determines how the breath will stop and allow the patient to exhale
Most breaths are time cycled
Any breath type that requires a set Ti is time cycled
These include the following breath types
PRVC
PCV
Volume Control

56. Cycling
Flow is also used to cycle a breath off

57. Cycling Flow is also used to cycle a breath off
Pressure Support Ventilation (PSV) is flow cycled

58. Cycling Flow is also used to cycle a breath off
Pressure Support Ventilation (PSV) is flow cycled
As the inspiratory flow starts to slow down the ventilator will sense that the lungs are getting full and cycle off allowing the patient to exhale

59. Cycling Flow is also used to cycle a breath off
Pressure Support Ventilation (PSV) is flow cycled
As the inspiratory flow starts to slow down the ventilator will sense that the lungs are getting full and cycle off allowing the patient to exhale
During that same breath it is being pressure limited

60. Cycling Flow is also used to cycle a breath off
Pressure Support Ventilation (PSV) is flow cycled
As the inspiratory flow starts to slow down the ventilator will sense that the lungs are getting full and cycle off allowing the patient to exhale
During that same breath it is being pressure limited
So pressure is being held in the lungs until the flow slows down at which time the ventilator will release the pressure and the patient exhales

61. Baseline Baseline is what limits are in effect during exhalation
Exhalation is passive
The only limit will be added pressure, i.e. PEEP
The baseline should be assessed via total PEEP to accurately measure the baseline

62. Rise Time or Slope
Rise time is part of the inspiration so could be considered a limiting factor

63. Rise Time or Slope
Rise time is part of the inspiration so could be considered a limiting factor
It is usually not included in the definition of a breath

64. Rise Time or Slope
Rise time is part of the inspiration so could be considered a limiting factor
It is usually not included in the definition of a breath
Rise time adjusts the initial flow rate of a breath

65. Rise Time or Slope
Rise time is part of the inspiration so could be considered a limiting factor
It is usually not included in the definition of a breath
Rise time adjusts the initial flow rate of a breath
It determines how much time is allowed for the breath to reach the peak flow needed to deliver the breath in the allotted time (Ti)

66. Rise Time/Slope
The less time the Rise time is the faster the breath ramps up to full speed

67. Rise Time/Slope
The less time the Rise time is the faster the breath ramps up to full speed
The longer the Rise Time is the slower the breath reaches peak flow

68. Rise Time/Slope
So if you have an inspiratory time of 1 second and you set your Rise Time at 0.2 seconds the peak flow will be reached in 0.2 seconds creating a blast of air at the beginning of the breath

69. Rise Time/Slope
So if you have an inspiratory time of 1 second and you set your Rise Time at 0.2 seconds the peak flow will be reached in 0.2 seconds creating a blast of air at the beginning of the breath
If you increase the Rise Time to 0.5 seconds the breath will not reach peak flow until half way through the breath creating a slower overall flow

70. Rise Time/Slope
A short Rise Time may be helpful in patient with high inspiratory demands, such as asthma

71. Rise Time/Slope
A short Rise Time may be helpful in patient with high inspiratory demands, such as asthma
A longer Rise Time is usually more comfortable because there is not the blast of air at the beginning

72. Rise Time/Slope
A short Rise Time may be helpful in patient with high inspiratory demands, such as asthma
A longer Rise Time is usually more comfortable because there is not the blast of air at the beginning
Where it is set is very patient dependent

73. Inspiratory Cycle Off
Inspiratory cycle off is part of the flow cycling breath

74. Inspiratory Cycle Off
Inspiratory cycle off is part of the flow cycling breath
Pressure Support Ventilation (PSV)

75. Inspiratory Cycle Off
Inspiratory cycle off is part of the flow cycling breath
Pressure Support Ventilation (PSV)
Flow cycling is used to end a PSV breath

76. Inspiratory Cycle Off
Inspiratory cycle off is part of the flow cycling breath
Pressure Support Ventilation (PSV)
Flow cycling is used to end a PSV breath
Normal inspiration goes to zero flow and then reverses the flow to exhale

77. Inspiratory Cycle Off
Inspiratory cycle off is part of the flow cycling breath
Pressure Support Ventilation (PSV)
Flow cycling is used to end a PSV breath
Normal inspiration goes to zero flow and then reverses the flow to exhale
Because it is difficult to achieve a tight seal on the circuit and patient, it is impractical to require the patient to get to zero flow before exhaling

78. Inspiratory Cycle Off
Inspiratory cycle off is part of the flow cycling breath
Pressure Support Ventilation (PSV)
Flow cycling is used to end a PSV breath
Normal inspiration goes to zero flow and then reverses the flow to exhale
Because it is difficult to achieve a tight seal on the circuit and patient it is impractical to require the patient to get to zero flow before exhaling
Flow cycling allow the breath to end prior to reaching zero flow

79. Inspiratory Cycle Off
Some ventilators have a preset flow rate that will cycle the PSV breath into exhalation

80. Inspiratory Cycle Off
Some ventilators have a preset flow rate that will cycle the PSV breath into exhalation
Some ventilators allow the flow rate to be adjusted

81. Inspiratory Cycle Off
Some ventilators have a preset flow rate that will cycle the PSV breath into exhalation
Some ventilators allow the flow rate to be adjusted
When setting Inspiratory Cycle Off it is a percentage

82. Inspiratory Cycle Off
Some ventilators have a preset flow rate that will cycle the PSV breath into exhalation
Some ventilators allow the flow rate to be adjusted
When setting Inspiratory Cycle Off it is a percentage
The percentage is based on the peak inspiratory flow achieved during the breath

83. Inspiratory Cycle Off
Some ventilators have a preset flow rate that will cycle the PSV breath into exhalation
Some ventilators allow the flow rate to be adjusted
When setting Inspiratory Cycle Off it is a percentage
The percentage is based on the peak inspiratory flow achieved during the breath
The percent is what determines when the breath will release the pressure and allow exhalation

84. Inspiratory Cycle Off
If you set the Inspiratory Cycle Off at 25% the inspiratory breath will end when the flow is 25% of the peak flow during that breath

85. Inspiratory Cycle Off
If you set the Inspiratory Cycle Off at 25% the inspiratory breath will end when the flow is 25% of the peak flow during that breath
If the peak flow was 60 lpm the breath will end at 25% of that or 15 lpm

86. Inspiratory Cycle Off
If you set the Inspiratory Cycle Off at 25% the inspiratory breath will end when the flow is 25% of the peak flow during that breath
If the peak flow was 60 lpm the breath will end at 25% of that or 15 lpm
The higher the % set the sooner the breath will be cycled off

87. Inspiratory Cycle Off
If you set the Inspiratory Cycle Off at 25% the inspiratory breath will end when the flow is 25% of the peak flow during that breath
If the peak flow was 60 lpm the breath will end at 25% of that or 15 lpm
The higher the % set the sooner the breath will be cycled off
This may cut off a patient breath early