PHYSIOLOGIE RESPIRATOIRE ADAPTE A LA VNI Pr Jean-Christophe M Richard

Pôle SAMU 74 Urgence et Réanimation Centre Hospitalier Annecy Genevois

CONFLICTS OF INTEREST

- Air Liquide Medical Systems (part time)

Financial support for research (Genève /Annecy/Angers)

-VYGON (personal fee for lectures)-SHILLER -MAQUET (NAVA)-COVIDIEN (PAV+) (personal fee for lectures)-DRAGER (SmartCare)-GE (FRC)

Equation of motion of the respiratory system

Paw + Pmus = (flow . R) + (Volume . E) + P0

patient

valve

Ventilator

Pressure

Flow60 l/min

Pressure mesured

Volume Control (flow regulated)

Tins

Oc

end-exp Alv. Pressure

end-insp Alv. Pressure

PresPel

• R= Pres / Flow• R= [Ppeak – Pplat] / Flow cmH20.L-1.s

• C= Vol / Pel• C= Vol / [Pplat – PEEPtot] mL. cmH20-1

• C= Vol / [Driving Pressure]

Volume Controlled

Rrs = 5 Rrs = 10 Rrs = 25

Ppeak

Pressure

Flow

Volume

Pressure

Flow

Volume

Crs = 50 Crs = 30 Crs = 20

Volume Controlled

Ppeak

Ventilator

Pressure setting

Airway pressure

0

20

20

Pressure regulated mode

1010

155

20

20 cmH2O

Pressure Controlled

Pressure

Flow

Volume

Rrs = 5 Rrs = 10 Rrs = 25

Vol min

Crs = 50 Crs = 30 Crs = 20

Pressure Controlled

Pressure

Flow

Volume

Vol min

VENTILATION ASSISTÉE

Volume assist control

How to set inspiratory flow ?

Inspiratory flow

60L/min (1L/sec)

R

C

V= V0 e-t/t

t = R x C

V

t

V03t = 96% V0

Dynamic hyperinflation and intrinsic PEEP

Intrinsic PEEP: 3 causes

• Dynamic hyperinflation• Flow limitation• Expiratory muscle recruitment

Pawcm H20

FlowL/s

VolumeL

20

40

0

Exp Pause Insp Pause

Park et Coll. Crit Care Med 2004

O2 vs. VS-PEP vs. VS-AI-PEP

PaO2/FiO2 PaCO2

CPAP vs PSV: effects on gas exchanges

Brochard et al. NEJM 1990

NIV reduces work of breathing

Lenique et al AJRCCM, 1997, 155, 500

9 patients

CPAP 10 cmH2OImprovement in compliance & resistance.

How does CPAP works for cardiac pulmonary edema?

Les points importants: