1936-2005 «Best» PEEP? Physiologic? Therapeutic? Optimal? Super? Preferred? Minimal? Right? Protective? Prophylactic?
1990-2000 Post cardiac arrest First day of mechanical ventilation 1990-1991 No patient received PEEP Mean V T 12mL/kg 1998-2000 All patients received PEEP Mean V T 9 ml/kg Wongsurakiat, 2004, 126, 1281
END-INSPIRATORY LUNG VOLUME CRF spont + CRF PEEP + V T
IDEAL 2005 PEEP Good oxygenation (PaO 2, PaO 2 /FiO 2 ) Recruitment and prevention of derecruitment (homogenous ventilation) Absence of cyclic dynamic compression and reexpansion of peripheral airawys Limited end-inspiratory pressures and volumes Limited negative hemodynamic effects
1936-2005 PEEP STORY Suter (1975) Kirby (1975) Lamy (1976) Matamis (1984) CTScan (1993)
«Best» PEEP? «PEEP coinciding with the maximum oxygen transport» Peter M Suter, NEJM, 1975, 284
Peter M Suter, NEJM, 1975, 284
Best PEEP : maximum oxygen transport -maximum cardiac output -maximum total compliance Arterial blood gases do no identify the level of PEEP resulting in maximum oxygen transport. Total static compliance is a usefull means of finding the degree of lung distention that provides the best gas exchange with the least risk of alveolar overdistension and lung rupture.
SUPER-PEEP? For Q s /Q T < 0.20 1975 (Kirby), 1995 (DiRusso) Maximum PEEP mean = 27-32cm H 2 O true max = 57 cm H 2 O Fluid balance + 23 L Inotropes and vasopressors +++ Digoxin if PEEP > 20 cm H 2 O!!! Barotrauma 49% Mortality 30%
Lamy, ARRD, 1976, 114, 267 CONDENSATION FIBROSIS EDEMA ATELECTASIS TRUE SHUNT DIFFUSION V/Q Baseline PaO 2 47+/-12 60+/-17 66+/-15 PEEP Effect (PaO 2,Q s /Q t ) effect 0 effect +, slow effect ++, fast Chronology early late early Mortality 82% 77% 52% VT 13 ml/kg, Ppeak 60
Matamis, Chest, 1984
Use of inflection point in the ascending limb of the static pressure-volume curve (indication of closing volume and reopening of alveoli and small airways) PREVENTION OF ALVEOLAR COLLAPSE
Use of inflection point in the ascending limb of the static pressure-volume curve (indication of closing volume and reopening of alveoli and small airways) PREVENTION OF ALVEOLAR COLLAPSE Argiras, BJA, 1987, 59, 1278 Sandhar, ICM, 1988, 14, 538 Oxygenation score Histological score EELV
50 45 40 35 EELV (ml) 30 25 20 15 10 5 0 Low PEEP LIP PEEP Sandhar, ICM, 1988, 14, 538
4 3,5 Hyaline Membrane Score 3 2,5 2 1,5 1 0,5 0 Low PEEP LIP PEEP Sandhar, ICM, 1988, 14, 538
Tout cela était trop simple! On oubliait l hétérogénéité pulmonaire!
Lung heterogeneity concept Axial distribution -cephalocaudal -anteroposterior Anatomical distribution -diffuse 20% -focal lobar 40% patchy 40% Microscopic distribution
DIFFUSE JJR,CCM, 2003 Red Gray Black White Non Aerated Poorly Aerated Normally Aerated Overinflation
LOBAR JJR,CCM, 2003 Red Gray Black White Non Aerated Poorly Aerated Normally Aerated Overinflation
Schiller, CCM, 2003,31,1126
PEEP-induced increase in FRC -Alveolar recruitment: decrease in gas volume in poorly or non aerated area -Alveolar inflation (aeration): increase in volume of normally aerated area -Alveolar overinflation: increase in the volume of overinflated area Nieszkowska, CCM, 2004, 32, 1496
Treggiari, CCM, 2002, 30, 1747
Duration Duration Duration Dynam ic Crs of MV of EIP > 35 of FiO2 > 0.5 < 20 ml/cmh2o OV ERDIST ENSION ANTERIOR LUNG SEGMENT S ALVEOLAR AIR CYSTS (43%) BRONCHIAL BRONCHIECT ASIS (62%) Treggiari, CCM, 2002, 30, 1747
Red Gray Black White Non Aerated Poorly Aerated Normally Aerated Overinflation ZEEP PEEP 15
The «price» of PEEP Overinflation: anatomical and regional distribution?! In 50% of «focal» (vs 0% of diffuse)! Non dependent caudal regions! COPD Nieszkowska, CCM, 2004, 32, 1496
10 50
Lim, CCM, 2004, 32,2378
Potential for recruitment??? 0,35 0,3 0,25 Lung Recruitment 0,2 0,15 0,1 0,05 0-0,05 0 5 10 15 PEEP level (cmh2o) ARDS p ARDS extrap Gattinoni, AJRCCM, 1998,
Lim, CCM, 2004, 32,2378
Lim, CCM, 2004, 32,2378
FiO² PEEP 0,3 12 0,3 14 0,4 14 0,4 16 0,5 16 0,5 18 0,5-0,8 20 0,8 22 0,9 22 1 22-24 NIH, NEJM, 2004, 351
FiO² PEEP 0,3 12 0,3 14 0,4 14 0,4 16 0,5 16 0,5 18 0,5-0,8 20 0,8 22 0,9 22 1 22-24
Best PEEP??? Balance -gas exchanges -mechanics -tissues oxygenation (CO, DO 2 ) Adapted for each patient -co-morbidity -origin of ARDS -morphology of ARDS -hemodynamic status -chronology
Best PEEP??? Method for choising optimal PEEP? (Ward, 2002, 30, 963) P flex or PEEP best? 68% P flex 86% P best 93% P flex or P best
Compliance maximale 45 40 35 Compliance 30 25 20 15 10 5 0 0 2 4 6 8 10 12 14 16 PEEP Infection abdominale Pneumonie
800 750 65 103 115 TIDAL VOLUME 700 650 600 11 24 270 340 360 0 550 500 0 2 4 6 8 10 12 14 16 PEEP
52 Tidal Volume (ml) 650 600 0 0 52 262 325 442 550 494 501 500 450 400 0 2 4 6 8 10 12 14
Best PEEP??? Target? (Oxygenation, mechanics, O 2 transport) Morphologic basis? (focal, diffuse) Mecanichal basis (pulmonary versus extra-pulmonary ARDS) Chronological basis (early versus late ARDS) Hemodynamic basis (volhemia, compliance, cardiac function)
Best PEEP??? Predisposing factors to lung overinflation -focal distribution of the loss of aeration -presence of lung emphysema -degree of lung inflation at ZEEP (COPD) «There is no validated tool available at the bedside for detecting and quantifying lung overinflation» Nieszkowska, CCM, 2004, 32, 1496
Universal Best PEEP is a soft dream! Price of PEEP is a reality!
CONSOLIDATION COLLAPSE Primum Movens Alveolar epithel injury Endothelial Injury Pathology Inflamm alveolar flooding Interstitial edema Consequence Consolidation Compression Site of action Alveoli Small Airway Clinical situation Primary ARDS Secondary ARDS Morphology "Lobar" "Diffus" Potential for recruitment Low High Risk of hyperinflation High Low ECW/ETOT (Nl = 0.5) 0,2 0,8 Hemodynamic risk of Paw High Low
VALI in patients without ALI at the onset of mechanical ventilation Gajic, CCM, 2004, 32, 1817 Patients sans ALI/ARDS 25% développent ALI dans les 5 premiers jours Facteurs de risque Haut V T (OR 1,3 par ml au-dessus de 6 ml/kg) Femmes Petites tailles Transfusions (OR 2,97) Pneumopathies pré-existantes (OR 3,6)
Suter s PEEP or Amato s PEEP? The lowest value of RV outflow impedance is associated with the better value of Crs. Schmitt, AJRCCM, 2001,29,1154 ZEEP SUTER AMATO PEEP 0 6+/-3 13+/-4 PaO2 65+/-17 81+/- 21 102+/-40 Crs 30 +/-8 35+/-9 27+/-8 SVI 26+/- 0.6 27 +/- 0.8 21+/-0.8