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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:
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