1. Neonatal Mechanical Ventilation
Mark C Mammel, MD
OF MINNESOTA
University of Minnesota
Children’s Hospital

2. Mechanical ventilation
What we need to do
Support oxygen delivery, CO2 elimination
Prevent added injury, decrease ongoing injury
Enhance normal development

3. Mechanical ventilation
Support oxygen delivery, CO2 elimination
Headbox O2
Cannula O2
CPAP ± IMV
Intubation, ventilation

4. Mechanical ventilation
Prevent added injury
Minimize invasive therapy
Optimize lung volume
Target CO2, O2
Use appropriate adjuncts
Manage fluids and nutrition

5. Mechanical ventilation
Enhance normal development
Manage fluids and nutrition
Encourage patient-driven support
Maintain pulmonary toilet- carefully

6. Support devices

7. Mechanical ventilation
Key concepts:
Maintain adequate lung volume
Inspiration: tidal volume
Expiration: End-expiratory lung volume
Support oxygenation and CO2 removal
Oxygenation: adequate mean airway pressure
CO2 removal: adequate minute ventilation

8. Mechanical ventilation
Key concepts:
Optimize lung mechanical function
Compliance: ∆V/∆P
Resistance: ∆Flow/∆P
Time constant: C x R

10. Boros SJ et al:
J Pediatr1977; 91:794

12. Mechanical ventilation: How does it work?
Patient
Inspiration
Patient
Exhalation

13. Mechanical Ventilation: Mode classification
A. Trigger mechanism
What causes the breath to begin?
B. Limit variable
What regulates gas flow during the breath?
C. Cycle mechanism
What causes the breath to end? B C A

14. A. Inspiratory Trigger Mechanism
Time
Controlled Mechanical Ventilation – NO patient interaction
Pressure
Ventilator senses a drop in pressure with patient effort
Flow
Ventilator senses a drop in flow with patient effort
Chest impedance / Abdominal movement
Ventilator senses respiratory/diaphragm or abdominal muscle movement
Diaphragmatic activity
NAVA- Neurally adjusted ventilatory assist

15. B. Limit Variable A B Pressure A. Pressure limited VolumeTi Ti
Pressure
A. Pressure limited
Volume
B. Volume limited A B

16. C. Cycle Mechanism What causes the breath to end?Ti Ti Ti
A. Time
All ventilators
B. Flow
Pressure support modes
C. Volume
Adult / pediatric ventilators
Pressure
Flow
Volume A B C

17. Basic waveforms

18. Time cycle- fixed Ti

19. Flow cycle- variable Ti with limit

20. Mechanical ventilation:
Which vent?
Conventional
Dräger Babylog 8000
Avea
Servo i
High frequency
SensorMedics oscillator
Bunnell HFJV

21. Conventional Ventilation
Modes:
CPAP
+/- Pressure support (PSV)
IMV/SIMV
+/- Pressure support (PSV), volume targeting
Assist/control (PAC)
+/- volume targeting

22. Continuous positive airway pressure: CPAP
Goal:
Support EELV in spontaneously breathing infant (optimize lung mechanics)
Delivery:
NeoPuff, other dedicated CPAP devices
HFNC
Using mechanical ventilator
May be done noninvasively or via ET tube (HFNC in extubated patients only)
Patients:
Newborn infants ≥26 wks with early distress
Infants in NICU with new distress or apnea
Extubated infants

23. Continuous positive airway pressure: CPAP
Setup:
NeoPuff, other dedicated CPAP devices:
Nasal prong interface
Set PEEP (4-6 cm H2O most common)
SiPAP: special type of CPAP. Uses 2 levels, usually 2-4 cm H2O different
HFNC
Nasal cannula interface
2-4 L/min flow
Monitoring
CPAP: airway pressure displayed and alarmed
HFNC: none

24. Early CPAP Columbia Presbyterian * * *p<0.0001 * *
gm Infants: Variation in CLD * % *
*p<0.0001 * *
Van Marter et al. Pediatrics 2000;105:

25. Intermittent mandatory ventilation: IMV/ SIMV
Goal:
Support EELV and improve Ve in spontaneously breathing infant requiring intubation
Eliminate breath-breath volume variation, cerebral blood flow abnormalities, allow patient control via synchronization of SOME breaths
Delivery:
Using mechanical ventilator
May be done noninvasively or via ET tube
Patients:
Newborn infants requiring intubation
Extubated infants with persistent distress

26. Intermittent Mandatory Ventilation: IMV/ SIMV
Setup:
ET tube interface
Variables:
Rate- range bpm; always synchronized
Volume- target volume 4-7 mL/kg
Pressure- Set peak pressure limit (usually 30 cmH2O). Pressure then adjust based on volume. Set PEEP 5-7 cmH2O
Time- set Ti at 0.3 – 0.5 sec based on pt size
Monitoring
Dynamic. Multiple alarm settings. All measured and calculated parameters may be displayed and trended

27. IMV- unsynchronized

28. Impact of synchronization

29. Assist/control: PAC Goal: Delivery: Patients:
Support EELV and improve Ve in apneic or spontaneously breathing infant requiring intubation
Eliminate breath-breath volume variation, cerebral blood flow abnormalities, allow patient control via synchronization of ALL breaths
Delivery:
Using mechanical ventilator
Done via ET tube
Patients:
Newborn infants requiring intubation

30. Assist/control: PAC Setup: ET tube interface Variables: Monitoring
Rate- set minimum acceptable rate, bpm; actual rate depends on patient effort
Volume- target volume 4-7 mL/kg
Pressure-
Peak pressure: Set limit (usually 30 cmH2O). Pressure then adjust based on volume.
PEEP: 5-7 cmH2O
Time- set Ti maximum at 0.3 – 0.5 sec based on pt size. Actual Ti varies with lung mechanics. Te varies with rate
Monitoring
Dynamic. Multiple alarm settings. All measured and calculated parameters may be displayed and trended

31. Assist/control- full synchronization

32. Conventional Ventilation
Variables- What does what?
Minute ventilation (Ve): PaCO2
Ve = RR x Vt
Vt changes with changing lung mechanics
Tools to change: PIP, PEEP, Ti, Te
Oxygenation: PaO2, SaO2
Mean airway pressure (Paw)
Oxygenation varies with lung volume, injury

33. Conventional Ventilation
Variables- What does what?
Minute ventilation (Ve): PaCO2
Ve = RR x Vt
Vt changes with changing lung mechanics
Tools to change: PIP, PEEP, Ti, Te

34. Assessment of Vt: PAC (no volume target)

35. Assessment of Vt: PAC, improved C

36. Assessment of Vt: PAC + V, imp C- no limit

37. Conventional Ventilation
Boros SJ, et al. Pediatrics 74;487:1984
Mammel MC, et al. Clin Chest Med 1996;17:603

38. Conventional Ventilation
Variables- What does what?
Oxygenation: PaO2, SaO2
Mean airway pressure (Paw)
Oxygenation varies with lung volume, injury
Tools to change: PIP, PEEP, Ti, Te

40. Lung Volume Optimize lung volume Pmax Popt Volume Pcl Pop Pressure
Define opening pressure, closing pressure, optimal pressure: dependent on estimation of lung volume
Problems: no useful bedside technology to measure either absolute or change in lung volume
Pmax
Popt
Volume
Pcl Pop
Pressure

41. Lung Volume Optimize lung volume SaO2 as volume surrogate
Tingay DG et al. Am J Resp Crit Care Med 2006;173:414

42. Assessment of Paw – Ti adjustment

43. Assessment of Paw – PEEP adjustment

44. Assessment of Paw – PIP adjustment

45. Assessment of Paw – Rate adjustment

46. Neonatal Mechanical Ventilation: Ventilator setup
IMV
SIMV
A/C
PSV Ti
sec
(flow signal)
Set limit sec RR
Set based on condition
Set lower limit for apnea
PIP
Set based on condition (Vt)
Set limit; based on Vt
PEEP
4-10 based on O2 needs, condition Vt
4-6 mL/kg
Flow
3-15 L/min
FiO2
Adjust based on O2 sats

47. Mechanical ventilation
What we know: general
Support affects pulmonary, neurologic outcomes
Greater impact at lower GA
VILI is real
Less is usually more

48. Mechanical ventilation
What we need to know
Who needs support?
Who needs what support?
Risk/benefit for various modalities
When (how) do you wean/stop support?