Driving Pressure What is it, and why should you care? Jonathan Pak MD March 2, 2017
Lancet 1967; 290: 319-323
Traditional Ventilation in ARDS Tidal Volume (V T ) = 10-15 ml/kg PBW PEEP = 5-12 cm H 2 O
Ventilator-Induced Lung Injury PIP: 14 PEEP: 0 PIP: 45 PEEP: 10 PIP: 45 PEEP: 0 Am Rev Respir Dis 1974; 110: 556-565
Ventilator-Induced Lung Injury High Volume High Pressure VILI Low Volume Low Pressure VILI
Ventilator-Induced Lung Injury Lung Volume Time
Ventilator-Induced Lung Injury Lung Volume VILI from Overdistension VILI from Open/Close Time
N Engl J Med 2000; 342: 1301-1308
V T 6 and 4 ml/kg PBW* P plat 30 PEEP 5 * Okay to increase V T up to 8 ml/kg PBW if P plat 30 N Engl J Med 2000; 342: 1301-1308
Ventilator-Induced Lung Injury Lung Volume VILI from Overdistension VILI from Open/Close Time
Ventilator-Induced Lung Injury Lung Volume VILI from Overdistension VILI from Open/Close Time
N Engl J Med 2004; 351: 327-337
Lower PEEP Group (same as ARMA) Higher PEEP Group (adapted from Amato et al, NEJM, 1998) N Engl J Med 2004; 351: 327-337
N Engl J Med 2004; 351: 327-337
V T 6 and 4 ml/kg PBW* P plat 30 PEEP 5 * Okay to increase V T up to 8 ml/kg PBW if P plat 30
V T 6 and 4 ml/kg PBW* P plat 30 PEEP 5 * Okay to increase V T up to 8 ml/kg PBW if P plat 30
Lower PEEP Group (same as ARMA) Higher PEEP Group (adapted from Amato et al, NEJM, 1998) N Engl J Med 2004; 351: 327-337
Protective Approach V T < 6 ml/kg High PEEP Driving Pressure (P plat - PEEP) < 20 cm H 2 O N Engl J Med 1998; 338: 347-354
Driving Pressure ( P) Driving Pressure PEEP Time
N Engl J Med 1998; 338: 347-354
Retrospective analysis APACHE II Mean PEEP in first 36 hours Driving Pressures in first 36 hours N Engl J Med 1998; 338: 347-354
N Engl J Med 2015; 372: 747-755
Model Variables Patient Variables Days on vent Age Apache III # Organ Failures Arterial ph PaCO 2 PaO 2 /FiO 2 ratio Tidal Compliance Ventilator Variables Tidal Volume (V T ) P plat PEEP FiO 2 Respiratory Rate P aw Driving Pressure ( P)
Matched PEEP Matched P Matched P Plat
Survival in Patients with Protective Vent Settings All with P plat 30 cm H 2 O and V T 7 ml/kg PBW Driving Pressure Median: 13 cm H 2 0 Plateau Pressure Median: 26 cm H 2 0 Tidal Volume Median: 6 mg/kg PBW
Combined Mortality by P
Survival Predicted by P in ALVEOLI
Barotrauma predicted by P, not VT
Essential Question Is driving pressure just a measure of disease severity, or can it be used to improve outcomes?
Driving Pressure ( P) Driving Pressure PEEP Time
Compliance (C) = V P C RS = V T P plat - PEEP
C RS = V T P plat - PEEP P = V T C RS
V T C RS > V T PBW
Determinants of P are V T and C RS Compliance Volume P V T Airway Pressure
Determinants of P are V T and C RS P Compliance Volume P V T Airway Pressure
Determinants of P are V T and C RS Compliance Volume P P V T Airway Pressure
Ventilator-Induced Lung Injury Lung Volume VILI from Overdistension VILI from Open/Close Time
Ventilator-Induced Lung Injury Lung Volume VILI from Overdistension VILI from Open/Close Time
Use P to Optimize PEEP Volume V T = 6 PEEP = 10 P = 18 Airway Pressure
Use P to Optimize PEEP Volume V T = 6 PEEP = 14 P = 14 Airway Pressure
Use P to Optimize PEEP Volume V T = 6 PEEP = 18 P = 18 Airway Pressure
Use P to Optimize PEEP Volume V T = 6 PEEP = 14 P = 14 Airway Pressure
Use P to Optimize V T Volume V T = 6 PEEP = 14 P = 16 Airway Pressure
Use P to Optimize V T Volume V T = 5 PEEP = 14 P = 14 Airway Pressure
Ventilator-Induced Lung Injury Lung Volume VILI from Overdistension VILI from Open/Close Time
Technical Questions What size increments to adjust PEEP? How long to wait before checking P after change in PEEP or V T? Role for recruitment maneuvers? How often to check P daily?
What Can You Do Today? Calculate P on ARDS patients Chart it
Ventilator Flowsheet
Ventilator Flowsheet
What Can You Do Today? Calculate P on ARDS patients Chart it (update EMR to calculate it) If P is high (>14-15): adjust PEEP decrease V T discuss neuromuscular blockade, proning, or transfer to an ECMO center
Conclusions P is easy to measure and track Increased P is associated with higher mortality in ARDS patients Adjustments in PEEP and V T can lower P Optimizing vent settings to lower P could improve outcomes, but has not been studied
P = P plat - PEEP = V T C RS