Modes of Ventilation - Speaker Deck

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Modes of Ventilation Kenrick Turner

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

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Terminology!

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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

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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

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• 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

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What is a breath?

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• 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…

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Spontaneous ventilation

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Spontaneous ventilation

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What is a mode?

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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

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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.

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What are the common modes?

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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

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Volume control (VC CMVs)

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Volume control (VC CMVs)

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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

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Pressure control (PC CMVs)

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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

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VC vs PC

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PRVC (VC CMVa,s)

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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

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CPAP/PS (PC CSVs)

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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

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APRV (PC IMVs,s) Airway Pressure Release Ventilation

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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