2. ventilatory modes

neonatal ventilator modes

1. DR/ MAHMOUD EL NAGGAR Egyptian Board of Neonatology May 25, 2016 1 2. VENTILATORY MODES

2. Definition of Mechanical Ventilation May 25, 2016 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 May 25, 2016 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 flow Continuous flow spontaneous

5. Mechanism of action of MV 5

6. Spontaneous Inspiration Hera NICU 2016 Volume Change Gas Flow Pressure Difference

7. Mechanical Ventilation Hera NICU 2016 Pressure Difference Volume Change Gas Flow Patient lung Inspiration

8. Basic design of ventilatory circuit Hera NICU 2016

9. Expiratory valve Hera NICU 2016

10. Unique challenges during neonatal ventilation Children ≠ Small adult Neonate ≠ Small child 10

11. Classification of Mechanical ventilators May 25, 2016 11 1- By power source: a) Pneumatic b) Electrical 2- By rate: a) Conventional b) High frequency

12. Classification of Mechanical ventilators May 25, 2016 12 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 May 25, 2016 13 5- Loop control of ventilator output: a) Opened loop b) Closed loop

14. Negative-pressure ventilators (iron lungs) Hera NICU 2016 Non-invasive ventilation first used in Boston Children’s Hospital in 1928 Used extensively during polio outbreaks in 1940s – 1950s

15. Polio outbreaks May 25, 2016 15 Iron lung polio ward at Rancho Los Amigos Hospital in 1953

16. Negative pressure ventilation 16

17. Recent –Ve pressure ventilator Hera NICU 2016

18. 1 st Positive pressure ventilation May 25, 2016 18 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 May 25, 2016 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 Hera NICU 2016

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 Hera NICU 2016

22. Open Vs closed loop ventilation May 25, 2016 22

23. May 25, 2016 23 1- Set tidal volume With 2- Safer pressure limit Target of neonatal ventilation

24. Conventional Neonatal Ventilators May 25, 2016 24 Pressure limited Time cycled Continuous flow ventilators

25. In all pressure controlled ventilation modes May 25, 2016 25 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? May 25, 2016 26 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 Hera NICU 2016

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29. May 25, 2016 29

30. Ideal ventilator design May 25, 2016 30 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 May 25, 2016 31 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 Hera NICU 2016 T i T e 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? May 25, 2016 33 IMV A/C SIPPV SIMV CPAP PS SIMV& PS CMV VG BIPAP ASV PCV VCV

34. D. Single or more type of breath during the mode? Hera NICU 2016

35. Classification of ventilatory modes May 25, 2016 35 Trigger: 1- Machine ( IMV) 2- Patient ( SIMV, SIPPV, PS) Control: 1- Pressure 2- Volume 3- Dual-control

36. Classification of ventilatory modes May 25, 2016 36 Cycling: 1- Time 2- Flow 3- Volume Types of breaths during ventilation: 1- Mandatory ( controlled) 2- Spontaneous 3- Assisted 4- Supported

37. Intermittent Mandatory Ventilation Controlled Mechanical Ventilation Hera NICU 2016 Trigger Controlled Cycling Types of breaths

38. 2 Types of breaths of IMV May 25, 2016 38

39. Hazards of desynchronization May 25, 2016 39 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 May 25, 2016 41     ∆ P   ∆ P E

42. May 25, 2016 42

43. Neurally adjusted ventilatory assistance May 25, 2016 43

44. Steps in the process of activating a ventilator breath(NAVA).

45. Trigger sensitivity May 25, 2016 45 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 Hera NICU 2016 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 Hera NICU 2016 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 May 25, 2016 48 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 May 25, 2016 49 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 Hera NICU 2016 Trigger Controlled Cycling Types of breaths Trigger window

51. May 25, 2016 51

52. 2 Types of breaths on A/C May 25, 2016 52

53. Synchronized Intermittent Mandatory Ventilation Hera NICU 2016 Trigger Controlled Cycling Types of breaths Trigger window

54. 3 Types of breaths of SIMV May 25, 2016 54

55. May 25, 2016 55

56. A/C Vs SIMV May 25, 2016 56 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) May 25, 2016 57 Trigger Controlled Cycling Types of breaths

58. P aw V • insp exp Patient or vent ilator initiated inspiration PSV cycled expiration Peak flow Drop to 15% of peak flow Pressure Support Ventilation Set P insp Hera NICU 2016

59. PSV Vs A/C May 25, 2016 59 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 May 25, 2016 60 Trigger Controlled Cycling Types of breaths

61. Proportional Assist Ventilation (PAV)& Neurally adjusted ventilatory assistance(NAVA) May 25, 2016 61 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 May 25, 2016 62

63. Volume Guarantee May 25, 2016 63 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) May 25, 2016 64 Several breaths may be needed to reach the target tidal volume after a sudden change. Maximum pressure

65. Principle of working of Volume Guarantee May 25, 2016 65 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 Hera NICU 2016

67. Open the lung and keep it opened May 25, 2016 67 The benefit of Volume T argeted V entilation can not be realized without ensuring that the tidal volume is evenly distributed throughout an (open lung)

68. Ventilate in safe window May 25, 2016 68

69. Volume guarantee why? May 25, 2016 69 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” Hera NICU 2016 PIP C lung V t Extubate Time

71. Patient control Hera NICU 2016

72. Mandatory Minute Ventilation MMV May 25, 2016 72 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 May 25, 2016 73

74. Relationship between patient effort and ventilator pressure during various ventilation modes.

75. Adaptive Support Ventilation !!!??? May 25, 2016 75 Body weight Sex ASV delivers pressure-controlled breaths using an adaptive (optimal) scheme . “ Optimal” means minimizing the mechanical work of breathing T he 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 by PIP Inspiratory time Ventilator respiration rate Assistance of each breath Inspiratory trigger Ventilatory mode RR& PIP Fixed Fixed Fixed No No IMV RR& PIP Fixed Fixed Fixed No Yes SIMV PIP Fixed Fixed Variable Yes Yes AC/ SIPPV PIP Fixed Variable Variable Yes Yes PSV

77. Thanks