Neonatal Mechanical Ventilation
Mark C Mammel, MD
University of Minnesota
Children’s Hospital
OF MINNESOTA
Mechanical ventilation
• What we need to do
– Support oxygen delivery, CO2 elimination
– Prevent added injury, decrease ongoing
injury
– Enhance normal development
Mechanical ventilation
• Support oxygen delivery, CO2 elimination
– Headbox O2
– Cannula O2
– CPAP ± IMV
– Intubation, ventilation
Mechanical ventilation
• Prevent added injury
– Minimize invasive therapy
– Optimize lung volume
– Target CO2, O2
– Use appropriate adjuncts
– Manage fluids and nutrition
Mechanical ventilation
• Enhance normal development
– Manage fluids and nutrition
– Encourage patient-driven support
– Maintain pulmonary toilet- carefully
Support devices
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
Mechanical ventilation
• Key concepts:
– Optimize lung mechanical function
• Compliance: ∆V/∆P
• Resistance: ∆Flow/∆P
• Time constant: C x R
Boros SJ et al:
J Pediatr1977; 91:794
Mechanical ventilation: How does it work?
Patient
Inspiration
Patient
Exhalation
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
A
C
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
B. Limit Variable
Ti
Ti
Pressure
A. Pressure limited
B. Volume limited
Volume
A
B
C. Cycle Mechanism
What causes the breath to end?
Ti
Ti
Ti
A
B
C
A. Time
Pressure
– All ventilators
B. Flow
– Pressure support modes
Flow
C. Volume
– Adult / pediatric ventilators
Volume
Basic waveforms
Time cycle- fixed Ti
Flow cycle- variable Ti with limit
Mechanical ventilation:
Which vent?
• Conventional



Dräger Babylog 8000
Avea
Servo i
• High frequency


SensorMedics oscillator
Bunnell HFJV
Conventional Ventilation
• Modes:
– CPAP
• +/- Pressure support (PSV)
– IMV/SIMV
• +/- Pressure support (PSV), volume targeting
– Assist/control (PAC)
• +/- volume targeting
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
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
Early CPAP
Columbia Presbyterian
500-1500 gm Infants: Variation in CLD
*
%
*
*
*
*p<0.0001
Van Marter et al. Pediatrics 2000;105:1194-1201
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
Intermittent Mandatory Ventilation:
IMV/ SIMV
• Setup:
– ET tube interface
– Variables:
• Rate- range 15-60 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
IMV- unsynchronized
Impact of synchronization
Assist/control: PAC
• Goal:
– 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
Assist/control: PAC
• Setup:
– ET tube interface
– Variables:
• Rate- set minimum acceptable rate, 40-60 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
Assist/control- full synchronization
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
• Tools to change: PIP, PEEP, Ti, Te
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
Assessment of Vt: PAC (no volume target)
Assessment of Vt: PAC, improved C
Assessment of Vt: PAC + V, imp C- no limit
Conventional Ventilation
•
Boros SJ, et al. Pediatrics 74;487:1984

Mammel MC, et al. Clin Chest Med
1996;17:603
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
Lung Volume
– 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
• Optimize
lung volume
Pcl Pop
Pressure
Lung Volume
• Optimize lung
volume
– SaO2 as volume
surrogate
Tingay DG et al. Am J Resp Crit Care
Med 2006;173:414
Assessment of Paw – Ti adjustment
Assessment of Paw – PEEP adjustment
Assessment of Paw – PIP adjustment
Assessment of Paw – Rate adjustment
Neonatal Mechanical Ventilation:
Ventilator setup
IMV
SIMV
A/C
PSV
Ti
0.2-0.5 sec
(flow signal)
0.2-0.5 sec
(flow signal)
0.2-0.5 sec
(flow signal)
Set limit- 0.30.5 sec
RR
Set based on
condition
Set based on
condition
Set lower limit Set lower limit
for apnea
for apnea
PIP
Set based on
condition (Vt)
Set based on
condition (Vt)
Set limit;
based on Vt
Set limit;
based on Vt
PEEP
4-10 based
on O2 needs,
condition
4-10 based
on O2 needs,
condition
4-10 based
on O2 needs,
condition
4-10 based
on O2 needs,
condition
Vt
4-6 mL/kg
4-6 mL/kg
4-6 mL/kg
4-6 mL/kg
Flow
3-15 L/min
3-15 L/min
3-15 L/min
3-15 L/min
FiO2
Adjust based
on O2 sats
Adjust based
on O2 sats
Adjust based
on O2 sats
Adjust based
on O2 sats
Mechanical ventilation
• What we know: general
– Support affects pulmonary, neurologic
outcomes
• Greater impact at lower GA
• VILI is real
• Less is usually more
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?