«Best» PEEP? Physiologic? Therapeutic? Optimal? Super? Preferred? Minimal? Right? Protective? Prophylactic?

Transcription

1 «Best» PEEP? Physiologic? Therapeutic? Optimal? Super? Preferred? Minimal? Right? Protective? Prophylactic?

2 Post cardiac arrest First day of mechanical ventilation No patient received PEEP Mean V T 12mL/kg All patients received PEEP Mean V T 9 ml/kg Wongsurakiat, 2004, 126, 1281

3 END-INSPIRATORY LUNG VOLUME CRF spont + CRF PEEP + V T

4 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

5 PEEP STORY Suter (1975) Kirby (1975) Lamy (1976) Matamis (1984) CTScan (1993)

6 «Best» PEEP? «PEEP coinciding with the maximum oxygen transport» Peter M Suter, NEJM, 1975, 284

7 Peter M Suter, NEJM, 1975, 284

8 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.

9 SUPER-PEEP? For Q s /Q T < (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%

10 Lamy, ARRD, 1976, 114, 267 CONDENSATION FIBROSIS EDEMA ATELECTASIS TRUE SHUNT DIFFUSION V/Q Baseline PaO 2 47+/ / /-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

11 Matamis, Chest, 1984

12 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

13 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

14 EELV (ml) Low PEEP LIP PEEP Sandhar, ICM, 1988, 14, 538

15 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

16 Tout cela était trop simple! On oubliait l hétérogénéité pulmonaire!

17 Lung heterogeneity concept Axial distribution -cephalocaudal -anteroposterior Anatomical distribution -diffuse 20% -focal lobar 40% patchy 40% Microscopic distribution

18 DIFFUSE JJR,CCM, 2003 Red Gray Black White Non Aerated Poorly Aerated Normally Aerated Overinflation

19 LOBAR JJR,CCM, 2003 Red Gray Black White Non Aerated Poorly Aerated Normally Aerated Overinflation

20 Schiller, CCM, 2003,31,1126

21 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

22 Treggiari, CCM, 2002, 30, 1747

23 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

24 Red Gray Black White Non Aerated Poorly Aerated Normally Aerated Overinflation ZEEP PEEP 15

25

26 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

27 10 50

28 Lim, CCM, 2004, 32,2378

29 Potential for recruitment??? 0,35 0,3 0,25 Lung Recruitment 0,2 0,15 0,1 0,05 0-0, PEEP level (cmh2o) ARDS p ARDS extrap Gattinoni, AJRCCM, 1998,

30 Lim, CCM, 2004, 32,2378

31 Lim, CCM, 2004, 32,2378

32 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, NIH, NEJM, 2004, 351

33 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,

34 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

35 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

36 Compliance maximale Compliance PEEP Infection abdominale Pneumonie

37 TIDAL VOLUME PEEP

38 52 Tidal Volume (ml)

39

40

41 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)

42 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

43 Universal Best PEEP is a soft dream! Price of PEEP is a reality!

44 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

45 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)

46 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+/ / /-40 Crs 30 +/-8 35+/-9 27+/-8 SVI 26+/ / /-0.8