Control of Breathing Under Mechanical Ventilation...Control of Breathing Under Mechanical Ventilation Ewan C. Goligher MD PhD Interdepartmental Division of Critical Care Medicine University

Control of Breathing Under Mechanical Ventilation

Ewan C. Goligher MD PhDInterdepartmental Division of Critical Care MedicineUniversity of Toronto

Disclosures

• Conflicts of Interest• Equipment and personal fees from Getinge• Equipment from Timpel

Outline

• Why we care: targeting respiratory effort• Control of ventilation• In non-ventilated subjects• On the ventilator

• Determinants of respiratory effort

Challenge: Managing Respiratory Drive

Respiratory drive & effort

P-SILI

Myotrauma

Respiratory drive and effort

Bertoni et al Crit Care 2019

Volutrauma

Myotrauma

Control of Ventilation

Vaporidi et al AJRCCM 2019

Control of Ventilation

Ve

PaCO2

PaCO2 =k ⋅V

.CO2

Ve.⋅ 1−Vd Vt( )

⇒Ve.=

1PaCO2

⋅k ⋅V

.CO2

1−Vd Vt( )

Control of Ventilation

Ve

PaCO2

PaCO2 =k ⋅V

.CO2

Ve.⋅ 1−Vd Vt( )

⇒Ve.=

1PaCO2

⋅k ⋅V

.CO2

1−Vd Vt( )

Control of Ventilation

Vaporidi et al AJRCCM 2019

PaCO2 =k ⋅V

.CO2

Ve.⋅ 1−Vd Vt( )

⇒Ve.=

1PaCO2

⋅k ⋅V

.CO2

1−Vd Vt( )

Control of Ventilation: Pattern

Ve

Vt

RR

Control of Ventilation: Respiratory Failure

Vaporidi et al AJRCCM 2019

Diaphragm dysfunction

Impaired mechanics

Control of Ventilation in Respiratory Failure

Vaporidi et al AJRCCM 2019

Ve

PaCO2

Control of Ventilation: Modes

Apneathreshold

Respiratory drive and effort

Bertoni et al Crit Care 2019

Volutrauma

Myotrauma

Determinants of Respiratory Muscle Pressure

Desired tidal volumeDesired inspiratory flow

Respiratory mechanics

Diaphragm function

Determinants of respiratory drive: sleep-wake status, acid-base, sedation, hypoxia, central demands

Ventilator pressure, flow, PEEP

Patient-Ventilator Interaction

Vaporidi et al AJRCCM 2019

Patient-Ventilator Interaction

Vaporidi et al AJRCCM 2019

Patient-Ventilator Interaction

Vaporidi et al AJRCCM 2019

Patient-Ventilator Interaction

Vaporidi et al AJRCCM 2019

Summary

• Why we care: targeting respiratory effort• Control of ventilation• In non-ventilated subjects• On the ventilator

• Determinants of respiratory effort