This document discusses pulmonary recruitment in ARDS patients and strategies for lung protection during mechanical ventilation. It describes how recruitment maneuvers using high airway pressures can reopen collapsed alveoli, preventing ventilator-induced lung injury from repeated opening and closing. The optimal settings for recruitment maneuvers and PEEP levels depend on a patient's recruitability, assessed via low-flow pressure-volume curves. PEEP levels are best guided by esophageal manometry or oxygen saturation to maintain alveolar stability and oxygenation without overdistension.

1. PV curve and lung recruitment Dr Jean-Michel Arnal Intensive Care Unit. Hôpital Font Pré Toulon France jean-michel@arnal.org

2. Mechanisms of Ventilator Induced Lung Injuries Mechanical Injury Barotrauma and/or volutraumaresulting from lung overdistension Atelectraumaresulting from repeated alveolar recruitment/ derecruitment Inflammatory Injury Biotrauma: alveolar inflammation

3. Prevention of VILI Reduced tidal volume and airway pressure limitation strategy Recruitment strategy: recruitment maneuver + PEEP to avoid derecruitment

4. What do we know about ARDS? Lower tidal volume and airway pressure limitation decreases mortality No effect of PEEP on mortality ARDS network. N Engl J Med 2000 ALVEOLI. Brower. N Engl J Med 2004 EXPRESS. Mercat JAMA 2008 LOVS. Meade. JAMA 2008

5. Effect of PEEP on mortality in ARDS Briel. JAMA 2010

6. What do we know about PEEP? PEEP does not recruit Collapse / re-expansion occurs during tidal volume Recruitment of previously collapsed lung with a recruitment maneuver PEEP may avoid collapse and derecruitment in a lung previously expanded/recruited

7. Recruitment Collapsed compliant airways/ alveoli Fluid occlusion of non collapsed airways

8. Am J Respir Crit Care Med 2006

9. 24 sur 26 patients Am J Respir Crit Care Med 2006

10. n = 68

11. Recruitability depends on Type of ARDS Time from the beginning of the disease Pressure Chest wall compliance

12. Type of ARDS Mechanism: extra pulmonary > pulmonary Localization: diffuse > lobar Riva. Crit Care Med 2008 Puybasset. Intensive Care Med 2000

13. Time from the beginning of the disease Early phase Protein rich edema fluids and polyneutrophils Late phase Fibrosing alveolitis

14. Pressure 24 on 26 patients Borges. Am J Resp Crit Care Med 2006

15. Chest wall compliance

16. Chest wall complianceAirway pressure is a rough estimate of transpulmonary pressure Talmor. Crit Care Med 2006

17. Assessment of recruitability Early in the management of ARDS When hemodynamic condition is controlled Low flow inflation and deflation PV curve from 0 to 40 cmH2O

18. Assessment of recruitability

19. Assessment of recruitabilityShape of the curve Grasso. AJRCCM 2005

20. Assessment of recruitabilityLinear compliance Maggiore. AJRCCM 2001

21. Assessment of recruitabilityLinear compliance CLIN = 37 mL/cmH2O CLIN = 83 mL/cmH2O

22. Assessment of recruitabilityHysteresis Demory. Intensive Care Med 2008

23. Assessment of recruitabilityHysteresis 6 798 cmH2O.ml 25 115 cmH2O.ml Demory. Intensive Care Med 2008

24. Assessment of recruitabilityHysteresis and volume difference at 20 cmH2O r2 = 0.97 Demory. Intensive Care Med 2008

25. Decision at the bedside

26. Decision at the bedside No recruitment maneuver Low PEEP: 5 – 10 cmH2O Recruitment maneuver High PEEP: > 10 cmH2O

27. Definition of a recruitment maneuver Use of a transient increase in transpulmonary pressure to reopen previously collapsed or non aerated lung units.

28. Volume recruited depends on Previous recruitment Transpulmonary inflation pressure Duration PEEP setting after the RM

29. Pressure and time Albert. J Appl Physiol 2009

30. Time  = 2,6 s Rothen. BJA 1999 12 anaesthetized patients with healthy lung

31. Optimal duration of the recruitment maneuver  = 2,3 ± 1,3 s n = 50 Arnal. Intensive Care Med [submitted]

32. Optimal duration of the recruitment maneuver * * Recruitment maneuver n = 50 Arnal. Intensive Care Med [submitted]

33. Recruitment maneuver at the bedsideConditions Passive patient: deep sedation ± paralysis Stable hemodynamic condition: ΔPP < 13% Cuff over inflated to avoid leaks No contraindications

34. Recruitment maneuver at the bedsideContraindications High intracranial pressure Emphysema Bronchopleural fistula Pregnancy Right heart failure

35. Recruitment maneuver at the bedsideSettings

36. Volume increase during a recruitment maneuver VRM= 100 mL VRM= 240 mL

37. How to set PEEP after recruitment maneuver? Low inflection point on PV curve Deflection point on PV curve Maximum PEEP while limiting Pplat around 28 cmH2O PEEP setting guided by esophageal measurement PEEP setting guided by SpO2 Hickling. AJRCCM 1998 Hickling. AJRCCM 2001 EXPRESS. Mercat JAMA 2008 Talmor. N Engl J Med 2009 Lapinski. Intensive Care Med 1999

38. PEEP setting guided by esophageal pressure Randomized controlled trial 61 ARDS patients Control: ARDSnet PEEP/FiO2 table Intervention: PEEP end-expiration Ppulm 0 - 10 cmH2O Talmor. N Engl J Med 2009

39. PEEP setting guided by esophageal pressure VT = 400 PEEP= 12 FiO2= 60% Ppulmins= 3 Ppulmexp= -6 Talmor. N Engl J Med 2009

40. PEEP setting guided by esophageal pressure VT = 320 PEEP= 24 FiO2= 60% Ppulmins= 12 Ppulmexp= 4 Talmor. N Engl J Med 2009

41. PEEP setting guided by esophageal pressure Talmor. N Engl J Med 2009

42. PEEP setting guided by esophageal pressure Talmor. N Engl J Med 2009

43. PEEP setting guided by esophageal pressure Talmor. N Engl J Med 2009

44. PEEP setting guided by esophageal pressure 65 years old woman, BMI = 32 Community acquired pneumonia

45. PEEP setting guided by SpO2 n = 14 Lapinski. Intensive Care Med 1999

46. PEEP setting guided by SpO2 Lapinski. Intensive Care Med 1999

48. PEEP does not recruit

49. Assessing recruitability is a pre-requisite for a rational setting of PEEP: low flow PV tool

50. High potential of recruitability patients: Recruitment strategy

51. Recruitment maneuver: 40 cmH2O (up to 60) for 10s

52. PEEP > 10 cmH20 (up to 25) guided by SpO2

53. Recruitment should be an early goal in the management of ARDS.Thank you…