1. VENTILATOR BASICS AND GRAPHICS
DR.AMENA FATIMA

2. COMMON TERMS

3. Pressures
PIP- peak inspiratory pressure:amount of pressure generated to deliver prescribed tidal volume. Varies depending upon resistance or compliance.

4. CAPACITIES
VITAL CAPACITY (VC):Volume ofgas exhaled after deepest possible inspiration
FUNCTIONAL RESIDUAL CAPACITY :volume of air remaining in lungs at the end of a normal expiration.This is the volume where gas exchange is constantly taking place.
TOTAL LUNG CAPACITY:max vol of air in the lungs after a max inspiration.

5. RESISTANCE
Opposition to flow of air through the airways.{tissue 20% +airway (Raw) 80%}
Raw=peak pressure(beginning)-plateau pressure(alveoli)/flow.
Raw directly proportion to length and flow,inversely to radius(r4)

6. COMPLIANCE
It is the relative ease with which the lung can be stretched with a given force.
C= delta V/delta P
STATIC COMPLIANCE-while there is no gases flows in or out of the lungs.( ml of H2O)
CST=exhaled tidal volume/plateau pressue –PEEP
DYNAMIC COMPLIANCE-while gases are moving in the lungs.(50-80ml H2O)
CDYN=exhaled tidal volume/PIP-PEEP

7. TIME CONSTANT
Time required, in seconds, to inflate a lung region to % of its filling capacity if the filling pressure was to remain constant.
T=R xC

8. TIDAL VOLUME
The amt of gas moved into or out of the lung in a single normal inspiration or expiration.
5-8ml/kg (350ml) vol reaching alveoli +2ml/kg (150ml) vol in conducting airway,,the anatomical dead space.
TV=minute ventilation/RR

9. WORK OF BREATHING
It consist of mechanical work-by respiratory muscles to overcome elastic force (compliance) and non-elastic force(resistance) to expand chest wall and lungs AND by breathing apparatus-circuit+ETT.
Metabolic work-oxygen consumption of respiratory muscles.O2 cost of breathing(5%)
Calculated by area under pressure-volume curve.
Increased WOB if inc.RR,use of accessory muscles of respiration,abnormal thoraco abdominal movements,>5% of total O2 consumption.

10. Phases of respiration Expiratory-inspiratory changeover Inspiration
Inspiratory –expiratory changeover
expiration

11. Phase variables Trigger variable-that initiates inspiration
Limit variable –places a maximum value on parameter chosen to be controlled during inspiration viz.,pressure,volume,flow or time.
Cycle variable-variable causing a breath to end
Baseline variable-describes what is happening to the breath during expiration.

12. Sensitivity Also known as triggering effort.
It is a ventilator setting contolled by clinician and is the inspiratory effort that the patient must apply to initiate inspiration.
If setting is too low-pt must generate more work to trigger gas flow.
If setting is too high-auto cycling of ventilator occurs.

13. Trigger variable
Time trigger-when ventilator initiates a breath at a preset time interval,determined by resp frequency.(controlled or mandatory breath)
Pressure trigger-here a decreased in pressure within inspiratory circuit is sensed and insp begins.normal sensitivity setting here is -0.5to -2 cm of H2O.take into consideration if peep is present.
with pressure triggering the patient works to create the neg pressure in circuit and continues this work for a period (in millisec)known as lag time.

14. Trigger variable
Flow triggering-a base flow of 5-10 l/min is set to ventilator and the clinician has to set how much the expiratory flow has to be decreased by the pt to initiate inspiration.it is usually 1-3l/min.

15. Limit variable
Preset target value for pressure,volume or flow that cannot be exceeded.
It has a max setting but doesnot cycled the ventilator.

16. Cycled variable
Volume cycled-the ventilator cycles to end inspiration and begin expiration when a predetermined volume is delivered in pts circuit.
Time cycled-inspiration ends and expiration begin after a pre determined time interval is reached.it can be done by simply timing mechanism or by setting the rate and adjusting the I:E ratio or percentage of inspiratory time.
Pressure cycled-insp ends and exp begins when a predetermined max pressure is reached.
Flow cycled-insp ends and exp begins when the flow rate decays to a predetermined percentage of its peak value-this crical flow rate in which cycling occurs is the terminal flow rate.

17. Baseline variable
It is the variable controlled during expiration time…,usually pressure is the variable controlled here.it is zero if the setting is at atmospheric pressure or the set PEEP when applied.

18. Inspiratory pause
When the lungs are held in an inflated state at a set pressure or volume for a specified time(<2 sec) at the end of inspiration.
Also called as inspiratory plateau or inflation hold.the readind of p-plateau taken at this point.

19. Inspiratory Pause } Inspiration Flow (L/min) Time (sec) Expiration

20. Types of breath Machine cycled Patient cycled
Mandatory breath-that is triggered,limited and cycled by ventilator.( tot WOB)
Assissted breath-triggered by pt ,then limited and cycled by ventilator.
Supported breath-triggered by patient,limited by ventilator and cycled by patient. Spontaneous breath-triggered,limited and cycled by patient.(tot WOB)

21. Spontaneous Breath
Inspiration
Time (sec)
Flow (L/min)
Expiration

22. Mechanical Breath
Inspiration
Time (sec)
Flow (L/min)
Expiration

23. Spontaneous Breath
Expiration
Paw (cm H20)
Time (sec)
Inspiration

24. Peak Inspiratory Pressure
Mechanical Breath
Peak Inspiratory Pressure
PIP
Paw (cm H2O)
Inspiration
Expiration TI TE }
PEEP
Time (sec)

25. Typical Flow Patterns
SQUARE
DECELERATING
ACCELERATING
SINE

26. Mechanical Ventilation
Graphics
SCALARS
LOOPS

27. scalars When pressure,volume or flow are plotted against time.
Variables on y-axis,time on x-axis
Flow/time
Pressure /time
Volume/time

28. Loops When ventilator variables plotted against ecah other.
Volume/pressure loop
Flow/volume loop

29. Flow/time scalar Flow in l/min on y-axis,time in sec on x-axis.
Flow above zero line is insp and below is expiratory.
Flow can be constant or decelerating.
Flow not affected by pt lung mechanics.
Uses:1.insp and exp flow rates.2.type of breath(vol/press control).3.type of inspiratory flow pattern(in vol ventilation).4.adequacy of insp time.5.presence of auto-PEEP.6.expiratory resistance and response to bronchodilators.7.presence and degree of continuous air leaks.

30. Mechanical Breath
Inspiration
Time (sec)
Flow (L/min)
Expiration

31. Inspiratory Flow Pattern
Beginning of expiration
exhalation valve opens
Peak inspiratory flow rate
PIFR
Inspiration
Insp. time TI
Expiratory Time TE
Flow (L/min)
Total cycle time
TCT
Time (sec)
Beginning of inspiration
exhalation valve closes
Expiration

32. Expiratory Flow Pattern
Beginning of expiration
exhalation valve opens
Inspiration
Expiratory time TE
Time (sec)
Flow (L/min)
Duration of
expiratory flow
Expiration
Peak Expiratory Flow Rate
PEFR

33. Inadequate Inspiratory Flow
Patient’s effort
Active Inspiration
Normal
Abnormal
Time (sec)
Flow
(L/min)

34. Air Trapping Normal Patient Time (sec) Flow (L/min) } Expiration
Inspiration
Normal
Patient
Time (sec)
Flow (L/min) }
Air Trapping
Auto-PEEP
Expiration

35. Response to Bronchodilator
Before
After
Time (sec)
Flow (L/min)
Long TE
PEFR
Shorter TE
Higher PEFR

36. volume/time scalar
Vol of gas in ml on y-axis and time in sec on x-axis.insp vol by up slpoe and exp vol on down slope as the set tidal volume is reached.
Uses: air leak or air trapping.

37. Inspiratory Tidal Volume
Volume vs Time
Inspiratory Tidal Volume
Volume (ml)
Inspiration
Expiration TI
Time (sec)

38. Air Leak/Air Trapping
Volume (ml)
Volume lost
Time (sec)

39. Pressure/time scalar
Pressure in cm of H2O on y-axis and time in sec on x-axis.the waveform rises at 0 at base line or from the applied PEEP.
The press curve resembles a shark fin,,negative deflection shows pt’s insp efforts.the depth denotes WOB( as in auto-peep,pneumothorax)
Uses:1.breath type delivered.,2.pt versus machine trigger.,3.work required to trigger the breath.,4.breathing timing.,5. adequacy of insp flow.,6. airway pressure.

40. Peak Inspiratory Pressure
Mechanical Breath
Peak Inspiratory Pressure
PIP
Paw (cm H2O)
Inspiration
Expiration TI TE }
PEEP
Time (sec)

41. CONTROLLED BREATH (Time Triggered) Mechanical Paw (cm H2O) Time (sec)
Time Triggered Breath

42. Assisted Breath (Patient Triggered)
Mechanical
Paw (cm H2O)
Time (sec)
Patient Triggered Breath

43. Assisted vs Controlled
Pressure (cmH20)
Time (sec)

44. Spontaneous vs. Mechanical
Inspiration
Paw (cm H2O)
Spontaneous
Expiration
Expiration
Inspiration
Time (sec)

45. Components of Inflation Pressure
PIP }
Transairway Pressure (PTA)
Paw (cm H2O)
Exhalation Valve Opens
Pplateau
(Palveolar)
Inspiratory Pause
Expiration
Begin Inspiration
Time (sec)
Begin Expiration

46. Inadequate Inspiratory Flow
Inadequate Flow
Adequate Flow
(cm H2O)
Paw
Time (sec)

47. Volume-pressure loops
Vol (ml) on y-axis,press(cm of H2O) on x-axis.
Lower curve of loop insp press and upper expiratory.the angle of curve depicts lung and chest wall compliance.
The v-p loops are elliptical in shape,pressure control loops are more rectangular,pltted in anti clockwise manner.
Patient efforts as trigger tail to the left of vertical axis.(larger tail=larger WOB)
The spontaneous breath v-p loop is plotted in a clock wise manner.

48. Pressure-Volume Loop (Type of Breath)
Vol (ml) I E I I
Paw
(cm H2O)
Controlled
Assisted
Spontaneous
I: Inspiration
E: Expiration

49. Components of Pressure-Volume LoopVT
Expiration
Volume (mL)
Inspiration
PIP
Paw (cm H2O)

50. PEEP and P-V Loop VT
PIP
Volume (mL)
PEEP
Paw (cm H2O)

51. Work of Breathing B A: Resistive Work B: Elastic Work A Volume (ml)
Pressure (cm H2O)

52. Inadequate Sensitivity
Volume (mL)
Paw (cm H2O)
Increased WOB

53. Air Leak/Air Trapping
Volume (ml)
Air Leak
Pressure (cm H2O)

54. Flow starvation/flow dyssynchrony
Active patient effort after initiation of ventilator indicates pt not receiving enough flow-flow starvation shown as concave appearance on insp limb.

55. Inadequate Inspiratory Flow
Volume
(ml)
Active Inspiration
Inappropriate Flow
Normal
Abnormal
Paw (cm H2O)

56. Increased Raw
Higher PTA
Volume
(ml)
Higher PTA
Paw (cm H2O)

57. Lung Compliance Changes and the P-V Loop
Volume Targeted Ventilation
Preset VT
COMPLIANCE
Increased
Normal
Decreased
Volume (mL)
Paw (cm H2O)
PIP levels

58. Lung Compliance Changes and the P-V Loop
Increased
Normal
Decreased
VT levels
Pressure Targeted Ventilation
Volume (mL)
Paw (cm H2O)
Preset PIP

59. With little or no change in VT
Overdistension
With little or no change in VT
Normal
Abnormal
Volume (ml)
Pressure (cm H2O)
Paw rises

60. Flow-volume loops Flow (L/min) on y axis and vol(ml) on x axis.
Mostly insp flow above horizontaland expi flow below.shape of exp loop determines the pts lung characteristics.
Uses:to assess the effect of bronchodilator therapy.,2.changes in airway resistance.,to detect auto-peep and vol leaks.

61. Flow-Volume Loop Inspiration PIFR FRC VT PEFR Expiration Flow (L/min)
Volume (ml)
FRC VT
Flow (L/min)
PEFR
Expiration

62. Air Leak Inspiration Expiration Volume (ml) Air Leak in mL Normal
Flow
(L/min)
Volume (ml)
Air Leak in mL
Normal
Abnormal
Expiration

63. Air Trapping Inspiration Expiration Flow (L/min) Volume (ml) Normal
Does not return
to baseline
Volume (ml)
Normal
Abnormal
Expiration

64. Increased Airway Resistance
Inspiration
Flow
(L/min)
Volume (ml)
Normal
Abnormal
“Scooped out”
pattern
Decreased PEFR
Expiration

65. Airway Secretions/ Condensate in the Circuit
Inspiration
Flow
(L/min)
Volume (ml)
Normal
Abnormal
Expiration

66. Modes of Ventilation Mechanical Spontaneous Volume Targeted Pressure

67. Spontaneous Breath
Flow
L/m
Pressure
cm H2O
Volume mL
Time (sec)

68. CPAP
Flow
L/m
Pressure
cm H2O
CPAP level
Volume mL
Time (sec)

69. PSV Patient Triggered, Flow Cycled, Pressure limited Mode Time (sec)
Flow Cycling
Flow
L/m
Set PS level
Pressure
cm H2O
Volume mL
Time (sec)

70. CPAP + PSV Flow Cycling Flow L/m Pressure cm H2O Volume mL Time (sec)
Set PS level
Pressure
cm H2O
CPAP level
Volume mL
Time (sec)

71. Controlled Mode (Volume- Targeted Ventilation)
Time triggered, Flow limited, Volume cycled Ventilation
Preset Peak Flow
Flow
L/m
Dependent on
CL & Raw
Pressure
cm H2O
Preset VT
Volume Cycling
Volume mL
Time (sec)

72. Assisted Mode (Volume-Targeted Ventilation)
Patient triggered, Flow limited, Volume cycled Ventilation
Flow
L/m
Pressure
cm H2O
Preset VT
Volume Cycling
Volume mL
Time (sec)

73. SIMV (Volume-Targeted Ventilation)
Pressure
Flow
Volume
(L/min)
(cm H2O)
(ml)
Spontaneous Breaths

74. Controlled Mode (Pressure-Targeted Ventilation)
Time Triggered, Pressure Limited, Time Cycled Ventilation
Time-Cycled
Pressure
Flow
Volume
(L/min)
(cm H2O)
(ml)
Set PC level
Time (sec)

75. Assisted Mode (Pressure-Targeted Ventilation)
Patient Triggered, Pressure Limited, Time Cycled Ventilation
Time-Cycled
Pressure
Flow
Volume
(L/min)
(cm H2O)
(ml)
Set PC level
Time (sec)

76. SIMV Mode (Pressure-Targeted Ventilation)
Flow
Volume
(L/min)
(cm H2O)
(ml)
Set PC level
Time (sec)
Spontaneous Breath

77. SIMV + PS (Pressure-Targeted Ventilation)
Time-Cycled
Flow-Cycled
Pressure
Flow
Volume
(L/min)
(cm H2O)
(ml)
Set PC level
Set PS level
Time (sec)
PS Breath

78. SIMV+PS (Volume-Targeted Ventilation)
Flow-cycled
Flow
Pressure
Volume
(L/min)
(cm H2O)
(ml)
Set PS level
PS Breath

79. SIMV + PS + CPAP (Pressure-Targeted Ventilation)
Flow
Volume
(L/min)
(cm H2O)
(ml)
Set PC level
Set PS level
CPAP level
Time (sec)

80. SIMV+PS + CPAP (Volume-Targeted Ventilation)
Flow
Pressure
Volume
(L/min)
(cm H2O)
(ml)
Set PS level
CPAP level
Time (sec)

81. Thank -you