1. 8 th Pulmonary Medicine Update February 7, 2008 Prone Ventilation for ARDS: Does it Do More Than Improve Oxygenation? Richard K. Albert, M.D. Chief of Medicine Denver Health Medical Center Professor of Medicine University of Colorado Adjunct Professor of Engineering and Computer Science University of Denver Denver Health
3. Objectives To describe: Hx of prone ventilation Effects on: - O 2 - Regional lung volume and perfusion - Response to recruitment maneuvers - VILI Clinical studies Unpublished data Denver Health
4. History of Prone Ventilation Douglas et al, ARRD 1977 Six pts, individual PaO 2 ’s, supine and prone, early and later in course Piehl and Brown, CCM 1976 Five case reports, mean ABG data Bryan, ARRD 1974 First suggested based on studies of sedation and paralysis on diaphragm Denver Health
5. Collaborators U. Washington U. Colorado Lisa Embree Wayne Lamm Josh Saliman Mike Graham David Leasa Sun Jong Kim Bob Guest Takashi Mutoh Ivor Douglas Robb Glenny Tom Robertson Jae Hwa Cho Jack Hildebrandt Mary Sanderson Seok Chan Kim Mike Hlastala Charlie Wiener Wayne Kirk Mayo Clinic Rolf Hubmayr U. Barcelona Johns Hopkins U. Iowa Jordi Mancebo Blaine Easley Ken Beck Brett Simon Eric Hoffman Denver Health
8. Mechanisms for Shunt Hypothesis: Dependent Lung: - More edema - More Q Prone positioning redistributes Q to ventral lung Shunt (Q without V) Redistribute Q to areas of V Redistribute V to areas of Q Denver Health
9. Effect of Prone Position on Regional Lung Injury Supine 10 7.5 5.0 2.5 BF Wet/Dry Dorsal Ventral Wiener, JAP 1990 D Mid ND D Mid ND Prone Dorsal Ventral Denver Health
10. Effect of Prone Position on Regional Perfusion Percent Flow 25 50 0 Supine Dorsal Ventral Wiener, JAP 1990 Mid D ND Prone Ventral Dorsal D Mid ND Denver Health
11. Zonal Theory of Pulmonary Blood Flow Distribution Flow Vertical Height Ppa > Ppv > P A Zone III Ppa > Ppv > P A Zone IV P A > Ppa > Ppv Zone I Ppa > P A > Ppv Zone II Denver Health
12. Theoretical Effect of Position on Perfusion Distribution Glenny, JAP 1991 Denver Health
13. Measured Effect of Position on Perfusion Distribution Glenny, JAP 1991 Denver Health
14. Zonal Theory of Pulmonary Blood Flow Distribution Flow Vertical Height Zone II Zone III Zone IV Top Bottom Denver Health
15. Effect of Position on Perfusion Distribution Glenny, JAP 1991 Denver Health
16. Effect of Prone Position on Gravitational Q Gradient in Humans Methods SPECT CT angiograms PET Methodological issues Assessing Q relative to what? - Gram of lung tissue ? - Alveolar volume ? Normal vs injured lung Effect of PEEP Area of interest Denver Health
17. Treatment of Hypoxemia Shunt (Q without V) Redistribute Q to areas of V Redistribute V to areas of Q Denver Health
18. Ventilation Distribution Milic-Emili, 1960s Gravitational distribution of Ppl - More negative in nondependent region Upright, supine, decubitus positions Denver Health
19. Effect of Prone Position on Ppl Gradient 0 3 -3 Ppl (cm H 2 O) Supine Prone Control Mutoh, JAP 1992 0.53 ± 0.1 D 0.17 ± 0.1 D ND ND Denver Health
20. Effect of PEEP on Regional Air Density Control Supine Prone Dep Non-Dep Dep Non-Dep 32 24 16 8 0 32 24 16 8 0 Denver Health
22. Dual Effect of Prone Position on Ppl Gradient in ALI 0 3 -3 Ppl (cm H 2 O) Supine Supine Prone Prone Control Edema Mutoh, JAP 1992 0.53 ± 0.1 D 0.17 ± 0.1 D 0.71 ± 0.1 D 0.27 ± 0.1 D ND ND ND ND Denver Health
23. Prone Position Overinflation and Regional V L Heterogeneity Supine Prone Injured Dep Non-Dep Dep Non-Dep 0 0 5 5 10 10 15 15 20 20 Denver Health
25. Effect of Body Position on Ppl Gradient How lungs fit into the thorax Lung distensibility Thorax distensibility - Lung volume - Chest wall mass - Air- or liquid-filled - Chest wall compliance - Abdominal mass - Abdominal compliance - Heart mass - Mediastinal mass - Diaphragm curvature Denver Health
30. Effect of Heart Weight (Supine) Albert, AJRCCM 2000 41% of left lung under the heart Malbouisson, ’00 - 64% of LLL - ARDS patients - heart size Denver Health
31. Effect of Heart Weight (Prone) Albert, AJRCCM 2000 Denver Health
32. Prone Position Lung Compression by Abdominal Contents Supine Prone Denver Health
33. ARDS Net Low-Stretch Ventilation Study ARDS Net Low-Stretch Ventilation Study Test of low-vs. “standard”-stretch - 6 vs 12 mL/kg (IBW) - PEEP and FIO 2 controlled by protocol - Mean PEEP ~ 8-9 cm H 2 O - 861 patients mortality 40% to 31% 9% absolute, 23% relative VILI/Biotrauma contributes to mortality NEJM 2000 Denver Health
34. Most ARDS Develops During Hospitalization Hudson et al, AJRCCM 1995 Denver Health
35. VILI/Biotrauma Pathophysiology Overdistension Endothelial/epithelial stretch Capillary stress failure Surfactant alteration Cyclical airspace opening and closing Shear stress Surfactant alteration by PEEP Something else Denver Health
36. Effect of Prone Position on Response to Recruitment Maneuver Pelosi, AJRCCM 2002 N = 10 ARDS 3 x 45 cmH 2 0/min EELV measured with helium Denver Health
37. Effect of Prone Position on Response to Recruitment Maneuver % Total Volume Right Lung Left Lung 100 75 50 25 0 Supine Supine Prone Prone OI PA WA NA Galiatsou, AJRCCM 2006 N = 21 Lobar ALI 40/20 x 30 sec PEEP to C L No ventral derecruitment Denver Health
38. Cyclical Airspace Opening and Closing End-Exhalation Mid-Inhalation End-Inhalation Lavage-Induced ALI, PEEP 10 cm H 2 O Denver Health
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40. Italian Prone Ventilation Trial (Gattinoni et al, NEJM 2001) Problems: Proning protocol - Application: 7 hrs/day ( 17 hrs/day supine) - Institution: late (decubiti) - Duration: 10 day maximum Protocol breaks: 134 in 53 pts Underpowered (N = 308) - Trend toward mortality (25% vs 21.1%, 16% ) - Stopped because of investigator bias No ventilation protocol No weaning protocol Denver Health
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42. French Prone Ventilation Trial (Guerin et al, JAMA 2004) Problems: Only 413 with ARDS or ALI (51%) - No condition-specific data Underpowered 81 (21%) crossovers (supine to prone) Proning protocol: - Application: 8 hrs/day (16 hrs/day supine) > 25% < 8 hrs/day - Duration: 4 days No ventilation protocol Denver Health
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44. Spanish Prone Ventilation Trial (Mancebo et al, AJRCCM 2006) Mortality (%) 20 40 60 80 Hospital 37/58 64% 39/75 52% ICU 34/58 59% 33/75 44% 25% P < 0.12 P < 0.02 (adjusted by SAPS) 19% P < 0.20 Denver Health Prone Supine
45. Prone Ventilation in ARDS Summary PaO 2 in 66-75% of patients - F I O 2 ( O 2 toxicity), PEEP ( overdistension) No substantive side-effects More homogeneous EELV - Overinflation - Airspace opening and closing - Recruitment Ventilator-induced lung injury (?) Biotrauma (?) Mortality (?) Denver Health
46. Some New Stuff Pre-B Cell Colony Enhancing Factor-1 First found in endometrial tissue Lung endothelium/epithelium in PMNs of septic pts IL-6 and IL-8 Induced by - Mechanical stress - LPS, IL-1 , TNF , IL-6 - VILI Denver Health
47. Prone Position High V T -Induced Regional PBEF-1 Expression 40 80 60 20 Relative PBEF-1 Expression (/ -Actin) Control Low V T (Spine) High V T (Supine) High V T (Prone) Cephalad Caudal Cephalad Caudal Non-Dependent Dependent Denver Health
49. Objectives Summarize: Hx of prone ventilation Effects on: - O 2 - Regional lung volume and perfusion - Response to recruitment maneuvers - VILI Clinical studies Unpublished data Denver Health
50. Prone Ventilation in ARDS Conclusion: Don’t do anything on your back – You might get ARDS Denver Health