mechanical ventilation pv curves. techniques for measurement 1. supersyringe 2. constant flow 3....
TRANSCRIPT
Mechanical Ventilation PV
Curves
Techniques for Measurement
1. Supersyringe
2. Constant Flow
3. Multiple Occlusion
Low Constant Flow
• Simple• Can be performed on ventilator (some types)• Avoids disconnect• Hysteresis • Heavy sedation or paralysis required• Flow 9 L/min for “quasi-static” conditions1
1Qin Lu, AJRCCM 1999;159:275-282Servillo, AJRCCM 1997;155:1629-1636
Radford, Tissue Elasticity, 1957
Surface forces due to air-liquidinterface
Gattinoni, ARRD 1987;136:730-736
Pflex
P
"safe"window
zone of overdistension
V
Pressure-Volume Curve
LIP
UIPzone of derecruitment and atelectasis
PV CurveNormal ARDS COPD
PV Curve
Normal
PV Curve
ARDS
P
"safe"window
zone of overdistension
V
atelectrauma
volutrauma
Lung Protective Ventilator Strategies
LIP
UIPzone of derecruitment and atelectasis
DON’T EVEN
THINKOF PARKING
HERE
Pressure
Vo
lum
e
Safe
zon
e
Overdistention
Derecruited
Lower Pflex, LIP
Upper Pflex, UIP
PV Curve in ARDS
Preventing Overdistention and Under-Recruitment
Injury“Lung Protective” Ventilation“Lung Protective” Ventilation
VOLUME
VOLUME
PressurePressure
Limit Distending PressureLimit Distending Pressure
Add PEEPAdd PEEP
Limit VT
PV Curve
COPD