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Neonatal Mechanical Ventilation Mark C Mammel, MD OF MINNESOT A University of Minnesota Childrens Hospital.

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Presentation on theme: "Neonatal Mechanical Ventilation Mark C Mammel, MD OF MINNESOT A University of Minnesota Childrens Hospital."— Presentation transcript:

1 Neonatal Mechanical Ventilation Mark C Mammel, MD OF MINNESOT A University of Minnesota Childrens Hospital

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

3 Mechanical ventilation Support oxygen delivery, CO 2 elimination –Headbox O 2 –Cannula O 2 –CPAP ± IMV –Intubation, ventilation

4 Mechanical ventilation Prevent added injury –Minimize invasive therapy –Optimize lung volume –Target CO 2, O 2 –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 CO 2 removal Oxygenation: adequate mean airway pressure CO 2 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

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

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? A BC

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

15 B. Limit Variable Pressure Volume AB B. Volume limited A. Pressure limited TiTi TiTi

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

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 H 2 O most common) –SiPAP: special type of CPAP. Uses 2 levels, usually 2-4 cm H 2 O different –HFNC Nasal cannula interface 2-4 L/min flow –Monitoring CPAP: airway pressure displayed and alarmed HFNC: none

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

25 Intermittent mandatory ventilation: IMV / SIMV Goal: –Support EELV and improve V e 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 cmH 2 O). Pressure then adjust based on volume. Set PEEP 5-7 cmH 2 O Time- set T i 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: –Support EELV and improve V e 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: 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 cmH 2 O). Pressure then adjust based on volume. –PEEP: 5-7 cmH 2 O Time- set T i maximum at 0.3 – 0.5 sec based on pt size. Actual T i varies with lung mechanics. T e 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 (V e ): P a CO 2 –V e = RR x V t V t changes with changing lung mechanics Tools to change: PIP, PEEP, T i, T e –Oxygenation: P a O 2, S a O 2 –Mean airway pressure (P aw ) Oxygenation varies with lung volume, injury Tools to change: PIP, PEEP, T i, T e

33 Conventional Ventilation Variables- What does what? –Minute ventilation (V e ): P a CO 2 –V e = RR x V t V t changes with changing lung mechanics Tools to change: PIP, PEEP, T i, T e

34 Assessment of V t : PAC (no volume target)

35 Assessment of V t : PAC, improved C

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

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

38 Conventional Ventilation Variables- What does what? –Oxygenation: P a O 2, S a O 2 –Mean airway pressure (P aw ) Oxygenation varies with lung volume, injury Tools to change: PIP, PEEP, T i, T e

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40 Lung Volume Optimize 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 P max P opt P cl P op Pressure Volume

41 Lung Volume Optimize lung volume – S a O 2 as volume surrogate Tingay DG et al. Am J Resp Crit Care Med 2006;173:414

42 Assessment of P aw – T i adjustment

43 Assessment of P aw – PEEP adjustment

44 Assessment of P aw – PIP adjustment

45 Assessment of P aw – Rate adjustment

46 Neonatal Mechanical Ventilation: Ventilator setup IMVSIMVA/CPSV TiTi sec (flow signal) sec (flow signal) 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 VtVt 4-6 mL/kg Flow 3-15 L/min FiO2FiO2 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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