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Neonatal Mechanical Ventilation

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Presentation on theme: "Neonatal Mechanical Ventilation"— Presentation transcript:

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

9

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

11

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 Volume
Ti 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

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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?


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