The document provides information on various aspects of mechanical ventilation including: 1. It defines mechanical ventilation as the movement of gas in and out of the lungs using an external mechanical device connected to the patient. 2. It discusses the various purposes of mechanical ventilation including facilitating gas exchange and reducing the work of breathing. 3. It describes the basic mechanisms and components involved in mechanical ventilation including the ventilator circuitry and expiratory valves. 4. It covers the different modes of ventilation including controlled mandatory ventilation, assisted/controlled modes, and pressure support ventilation. It discusses the importance of patient-ventilator synchrony.

1. DR/ MAHMOUD EL
NAGGAR
Egyptian Board of NeonatologyJune 1, 2016
1
2. VENTILATORY MODES

2. Definition of Mechanical
Ventilation
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2
Mechanical ventilation is the
movement of gas in and out of
the lung by an external source
(an automatic mechanical device)
connected directly to the patient.

3. Purpose of MV
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3
 Facilitate alveolar ventilation and carbon dioxide
removal.
 Provide adequate tissue oxygenation
 Reduce the work of breathing
 Relieve respiratory distress and Reverse respiratory
muscle fatigue
 Permit lung healing
 Avoid complications

4. Mechanism of action of MV
Patient
lung
Expiration
Patient
lung
Inspiration
Expiratory valve
Leak
Continuous flowContinuous flow
spontaneous

5. Mechanism of action of MV
5

6. Spontaneous Inspiration
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Volume Change
Gas Flow
Pressure Difference

7. Mechanical Ventilation
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Pressure Difference
Volume Change
Gas Flow Patient
lung
Inspiration

8. Basic design of ventilatory
circuit
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9. Expiratory valve
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10. Unique challenges during
neonatal ventilation
Children ≠ Small adult
Neonate ≠ Small child
10

11. Classification of Mechanical
ventilators
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 1- By power source:
a) Pneumatic
b) Electrical
 2- By rate:
a) Conventional
b) High frequency

12. Classification of Mechanical
ventilators
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 3- By pressure relationship to the patient:
a) Negative
b) Positive
 4- By cycling mode at termination of inspiration:
a) Volume cycling
b) Pressure cycling
c) Flow cycling
d) Time cycling
e) Mixed cycling

13. Classification of Mechanical
ventilators
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 5- Loop control of ventilator output:
a) Opened loop
b) Closed loop

14. Negative-pressure ventilators
(iron lungs)
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•Non-invasive ventilation first used in Boston Children’s Hospital in 1928
•Used extensively during polio outbreaks in 1940s – 1950s

15. Polio outbreaks
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Iron lung polio ward at Rancho Los Amigos Hospital in 1953

16. Negative pressure
ventilation16

17. Recent –Ve pressure
ventilator
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18. 1st Positive pressure
ventilation
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• Invasive positive
pressure ventilation
first used at
Massachusetts General
Hospital in 1955
• Now the modern
standard of mechanical
ventilation

19. Volume control Vs Pressure
control
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19

20. Volume control is good and
bad
 Guaranteed tidal volume, even with variable
compliance and resistance
 Less atelectasis compared to pressure
control
 Can cause excessive airway pressure
 The limited flow available may not meet the
patient desired inspiratory flow rate –
asynchrony
 Leaks leads to volume loss
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21. Pressure control is good and
bad
 Limit excessive airway pressure
 Improve gas distribution
 Less tidal volume as pulmonary mechanic
change
 Potentially excessive VT as compliance
improves
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22. Open Vs closed loop
ventilation
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23. June 1, 2016
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1- Set tidal volume
With
2- Safer pressure limit
Target of
neonatal
ventilation

24. Conventional Neonatal
Ventilators
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Pressure limited
Time cycled
Continuous flow
ventilators

25. In all pressure controlled
ventilation modes
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Tidal Volume supplied
depend on:
1- PIP- PEEP
2- Lung mechanics
3- Respiratory drive
of the patient

26. Why volume control not
suitable of newborn?
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 Use of small number of tidal volumes
 Leak around un-cuffed ET
 True tidal volume is influenced by ventilator
circuit compliance
 Comprisable volume of the circuit including the
humidifier, can affect the tidal volume

27. Breath Types during mechanical
ventilation
 Mandatory (controlled)
 Ventilator does the work
 Ventilator controls start and stop
 Spontaneous
 Patient takes on work
 Patient controls start and stop
 Assisted
 Patients triggers the breath
 The ventilator delivers the breath as per control variable
 Supported
 Patients triggers the breath
 Ventilator delivers pressure support
 Breath cycles at set flow
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28. Hera NICU 2016

29. June 1, 2016
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30. Ideal ventilator design
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 Achieve all the important goals of mechanical
ventilator
 Provide a variety of modes that can ventilate
even the most challenging lung diseases.
 Has monitoring capabilities to adequately
assess the ventilator and patient performance.
 Has safety features and alarms that over lung
protective strategies.
 Neonatal ventilator.

31. Ideal ventilator mode
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The mode which deliver a breath that:
 Synchronized with the patient spontaneous
breathing
 Maintain adequate and consistent tidal volume and
minute ventilation at low airway pressure.
 Response to rapid change of lung mechanic or
patient demands.
 Provide the lowest possible work of breathing.
A mode of ventilation is only as good as the
operator who applies it.

32. Anatomy of Pressure waveform
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Ti Te
Pressure
Begin
inspiration
Cycle to expiration
Time
Flow determines rate
of rise and reaching
peak pressure
Pressure limited =
“PIP”
PEEP
∆p
MAP

33. Which mode?
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IMV
A/C SIPPV
SIMV
CPAP
PS
SIMV&
PS
CM
V
VG
BIPAP ASV
PC
V
VCV

34.  D. Single or more type of breath
during the mode?
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35. Classification of ventilatory
modes
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 Trigger:
1- Machine ( IMV)
2- Patient ( SIMV, SIPPV, PS)
 Control:
1- Pressure
2- Volume
3- Dual-control

36. Classification of ventilatory
modes
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 Cycling:
1- Time
2- Flow
3- Volume
 Types of breaths during ventilation:
1- Mandatory ( controlled)
2- Spontaneous
3- Assisted
4- Supported

37. Ventilation
Controlled Mechanical
Ventilation
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 Trigger
 Controll
ed
 Cycling
 Types of
breaths

38. 2 Types of breaths of IMV
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39. Hazards of desynchronization
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 Baby fighting with the ventilator
 Inconsistent tidal volume delivery
 Inefficient gas exchange
 Increase the work of breathing
 Abnormally high intra-thoracic and intra-
pulmonary pressures leads to Barotrauma
 Decreased venous return
 Increase intra-cranial pressure leads to IVH
 Sub-optimal training of respiratory muscle

40. So, synchrony is extremely important
and can be achieved by detecting infant’s
inspiratory effort and using it to trigger
positive pressure inflation (triggered-
ventilation).

41. Patient trigger ventilation
sensors
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+ −
∆ P⟇
∆ P
E

42. June 1, 2016
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43. Neurally adjusted ventilatory
assistance
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44. Steps in the process of activating
a ventilator breath(NAVA).

45. Trigger sensitivity
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 It determine how easy to the patient to trigger
the ventilator to deliver a breath.
 Increase the sensitivity improve patient
ventilator synchronization.
 High sensitivity my result in false or auto-
triggering.

46. The Neonatal flow sensor
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 Hot wire anemometer
 Sensitive to 0.17 mL
 0 - 30 lpm range
 Weighs 10 grams
 0.5-1 mL added
deadspace
 Virtually no resistance
 Inexpensive
 6 month use

47. Flow Sensor Measurement
Principle
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Hot wire anemometer:
• Two tiny platinum wires are heated to 400°C
• One wire is shaded to determine direction of gas flow
• Wire cooling is proportional to gas flow
• Flow is integrated with time for volume measurement

48. Limitations of the flow sensor
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 If ET leak, expiratory tidal volume may be
underestimated.
 Imposing 1 ml of a dead space , which may
increase the WOB in very tiny preterm.
 If less than the expected expiratory tidal
volume due to ET leak is registered as a
negative flow and trigger a ventilator breath,
auto-triggering.

49. Limitations of the flow sensor
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 Humidity; water will create significant
fluctuations of accuracy.
 Secretions- surfactant; reading above or below
baseline in the presence of zero flow
 Very delicate-breaks easily, wears-out due to
processing and age

50. Assist/Control
Synchronized Intermittent Positive Pressure
Ventilation
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2016
 Trigger
 Controll
ed
 Cycling
 Types of
breaths
Trigger window

51. June 1, 2016
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52. 2 Types of breaths on A/C
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53. Synchronized Intermittent
Mandatory Ventilation
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 Trigger
 Controll
ed
 Cycling
 Types of
breaths
Trigger
windo
w

54. 3 Types of breaths of SIMV
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55. June 1, 2016
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56. A/C Vs SIMV
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 More stable tidal volume
 Less tachypnea
 Smaller blood pressure fluctuation
 Smaller tidal volume
 Lower work of breathing
 Faster weaning from mechanical ventilator

57. Pressure support ventilation
(PSV)
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 Trigger
 Controll
ed
 Cycling
 Types of
breaths

58. Paw
V
•
insp
exp
Patient or
vent ilator
initiated
inspiration PSV cycled
expiration
Peak flow
Drop to 15%
of peak flow
Pressure Support Ventilation
Set Pinsp
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59. PSV Vs A/C
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 PSV, Allow the newborn more control over the
respiratory pattern, with synchronization at the
end of inspiration not only the beginning.
 PSV, Decreasing asynchrony by minimize the
chance of active expiration against high
positive pressure.
 PSV, Automatically adjust Ti according to
change in patient time constant breath by
breath.
 PSV, Allow the infant to sigh as needed to
prevent atelectasis.

60. Synchronized intermittent
mandatory ventilation &
pressure support
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 Trigger
 Controll
ed
 Cycling
 Types of
breaths

61. Proportional Assist Ventilation (PAV)&
Neurally adjusted ventilatory
assistance(NAVA)
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 New ventilatory modes designed to assist
spontaneous ventilation
 The breath delivered is similar to PS but the
pressure support level is variable and is
proportional to patient spontaneous effort
a) The harder the patient work = the more
support by ventilator
b) The less the patient work = the less
support is provided

62. Tidal volume
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63. Volume Guarantee
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Working principle of Volume Guarantee. According to
a set tidal volume, inspiratory pressure is
automatically regulated by the ventilator.

64. Volume Guarantee (Dual-Control
Mode)
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Several breaths may be needed to reach the
target tidal volume after a sudden change.
Maximum
pressure

65. Principle of working of Volume
Guarantee
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Test breath
Measure Vt
Inspiratory
pressure
Same
inspiratory
pressure
Inspiratory pressure
Compare to set Vt
More
Equal
Less

66. Why volume targeted ventilation in
neonate?
Consistent VT Stable PaCO2 Stable CBF Less IVH
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67. Open the lung and keep it
opened
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The benefit of
Volume Targeted
Ventilation can not
be realized without
ensuring that the
tidal volume is
evenly distributed
throughout
an (open lung)

68. Ventilate in safe window
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69. Volume guarantee why?
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 It is volu-trauma than baro-trauma
 More stable tidal volume
 Wean PIP if lung mechanics improved
 Less hypo-capnea
 Work better with A/C than SIMV
 Bio-trauma decreased with TV 5ml/kg
 Faster weaning from mechanical ventilator

70. Pressure Support + Volume
Guarantee
Concept of “Auto-weaning”
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PIP
C lung
Vt
ExtubateTime

71. Patient control
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72. Mandatory Minute Ventilation
MMV
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 Guarantee a minimum minute ventilation ( RR x
TV)
 If the patient maintain a MV above the set MV this
mode will function like PS mode
 If the patient MV falls below the set MV the mode
will deliver mandatory breaths ( SIMV or IMV +
VG), only the numbers of breaths that required to
return patient MV to the set MV
Depends on the patient ventilatory drive
When the spontaneous breathing increased,
fewer mandatory breaths will be provided

73. PC- MMV
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74. Relationship between patient
effort and ventilator pressure
during various ventilation
modes.

75. Adaptive Support Ventilation
!!!???
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 Body weight
 Sex
 ASV delivers pressure-
controlled breaths using an
adaptive (optimal) scheme .
 “Optimal” means minimizing
the mechanical work of
breathing
 The machine selects a tidal
volume and frequency that the
patient’s brain would
presumably select if the patient
were not connected to a
ventilator.
 This pattern is assumed to
encourage the patient to
generate spontaneous breaths.

76. Different ventilatory modes
and their characteristics
Weaning byPIP
Inspiratory
time
Ventilator
respiration
rate
Assistance
of each
breath
Inspiratory
trigger
Ventilatory
mode
RR&
PIP
Fixe
d
Fixe
d
Fixe
d
NoNoIMV
RR&
PIP
Fixe
d
Fixe
d
Fixe
d
NoYesSIM
V
PIPFixe
d
Fixe
d
Variabl
eYesYesAC/
SIPP
V

77. Thanks