Modes of Ventilation

Modes of Ventilation

An introduction to the common modes of invasive ventilation in critical care.

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Kenrick Turner

May 13, 2020
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Transcript

  1. Modes of Ventilation Kenrick Turner

  2. Intro Common modes De ine “mode” Loops Lung protective ventilation

  3. Terminology!

  4. Chatburn Maquet Hamilton Dräger VC CMVs VC (S)CMV VC CMV

    VC CMVd VC VC A/C PC CMVa,s PRVC APVcmv VC CMV Auto low PC IMVa,s SIMV (PRVC) + SP APVsimv VC SIMV Auto low VC IMVs,s SIMV (VC) + PS SIMV VC SIMV VC IMVa,s ASV VC MMV PC CMVs PC P CMV PC CMV PC IMVs,s BI VENT APRV or DuoPAP PC BIPAP PC IMVoi,oi ASV PC CSVs CPAP/PS SPONT SPN CPAP/PS PC CSVa VS VS SPN CPAP/VS PC CSVr NAVA SPN PPS
  5. Ventilation: deliver fresh gas to the alveoli Diffusion: gas exchange

    across the blood-gas interface Blood low: transport of gas from the lungs Ventilation is but one component Oxygen delivery
  6. • Minute ventilation = RR × TV • Pressure gradient

    = A-a equation (Patm , FiO2 , MV, ?RQ) • Surface area = volume of lungs available for ventilation (Pmean ) Invasive ventilation provides control over CO2 clearance O2 diffusion Gas exchange in general
  7. What is a breath?

  8. • 1 cycle of positive & negative low on a

    low-time curve • Assisted either completely, partially, or not at all • Limited by a ixed low or ixed pressure over time • Classi ied by its trigger and cycling (patient vs machine) A breath…
  9. Spontaneous ventilation

  10. Spontaneous ventilation

  11. What is a mode?

  12. Traditional classi ication Trigger Limit Cycling Event that starts inspiration

    Factor that controls the inspiratory low Event that stops inspiration Mandatory (time) Spontaneous ( low or pressure) Flow–limited Pressure–limited Volume Time Pressure
  13. Chatburn classi ication Control variable Breath sequence Target scheme(s) Limit

    Trigger + Cycling Ventilator autonomy to achieve goals Volume control Pressure control Continuous Spontaneous Ventilation (CSV) Intermittent Mandatory Ventilation (IMV) Continuous Mandatory Ventilation (CMV) Set–point (s) Dual (d) Bio-variable (b) Servo (r) Adaptive (a) Optimal (o) Intelligent (i) Chatburn et al. A taxonomy for mechanical ventilation. Respir Care. 2014 Nov;59(11):1747 63.
  14. What are the common modes?

  15. Chatburn Maquet Hamilton Dräger VC CMVs VC (S)CMV VC CMV

    VC CMVd VC VC A/C PC CMVa,s PRVC APVcmv VC CMV Auto low PC IMVa,s SIMV (PRVC) + SP APVsimv VC SIMV Auto low VC IMVs,s SIMV (VC) + PS SIMV VC SIMV VC IMVa,s ASV VC MMV PC CMVs PC P CMV PC CMV PC IMVs,s BI VENT APRV or DuoPAP PC BIPAP PC IMVoi,oi ASV PC CSVs CPAP/PS SPONT SPN CPAP/PS PC CSVa VS VS SPN CPAP/VS PC CSVr NAVA SPN PPS
  16. Control variable Breath sequence Target scheme PRVC Volume CMV Adaptive,

    Set–point CPAP/PS Pressure CSV Set–point VC Volume CMV Set–point APRV/Bivent Pressure IMV Set–point, Set–point
  17. Volume control (VC CMVs)

  18. Volume control (VC CMVs)

  19. Volume control (VC CMVs) ! " Simple Barotrauma/high airway pressures

    Guaranteed ventilation Circuit leaks poorly tolerated Ppeak & Pplateau easily distinguished Constant high low in inspiration requires deep sedation
  20. Pressure control (PC CMVs)

  21. Pressure control (PC CMVs) ! " “Physiological” decelerating low Unpredictable

    tidal volumes/volutrauma Lower Pmean for a given TV Changes to I:E ratio in luence TV Compensates for leaks (within reason) Potential inadequate ventilation in severe bronchospasm
  22. VC vs PC

  23. PRVC (VC CMVa,s)

  24. PRVC (VC CMVa,s) ! " “Physiological” decelerating low Potential inadequate

    ventilation in severe bronchospasm Guaranteed ventilation Not universally available on all vents Adjusts for changes in airways resistance/compliance
  25. CPAP/PS (PC CSVs)

  26. CPAP/PS (PC CSVs) ! " “Physiological” decelerating low Unpredictable tidal

    volumes/volutrauma Lower Pmean for a given TV Changes to I:E ratio in luence TV Compensates for leaks (within reason) Potential inadequate ventilation in severe bronchospasm Same as Pressure Control
  27. APRV (PC IMVs,s) Airway Pressure Release Ventilation

  28. APRV (PC IMVs,s) ! " Maximises recruitment & reduces FiO2

    “constant recruitment manoeuvre” Hypovolaemia/cardiovascular instability poorly tolerated Spontaneous ventilation allowed No studies demonstrate mortality bene it Might minimise atelectrauma/biotrauma Infrequently available on vents Lack of doctor/nursing familiarity
  29. Curve pattern recognition

  30. Leak

  31. Gas trapping/Dynamic hyperin lation Insu icient expiratory time

  32. High airway resistance e.g. bronchospasm

  33. ? Slides available at: https://speakerdeck.com/kenrick/modes-of-ventilation