ARDS and Ventilators PG26 Update in Surgical Critical Care October 9, 2013 Pauline K. Park MD, FACS, FCCM University of Michigan School of Medicine Ann Arbor, MI
OVERVIEW New Berlin definition of ARDS HFOV Prone Positioning Early neuromuscular blockade Transpulmonary pressure guided ventilator management ECMO Prevention
Prospective, population-based cohort study King County, Washington Incidence ALI 78.9 cases/100,000 person-years ARDS 58.7 cases/100,000 person-years In-hospital mortality rate 38.5-41.1% Day 3, Improved 28.6% Day 3, Failed to improve 41% Most common risk factors pulmonary 46% severe sepsis 33%
Pooled ARDS Mortality 1981-2004 Phua J, AJRCCM 2009;179:220 7
Question 1 The Berlin Definition of Severe ARDS includes assessment of which of the following? A. Oxygenation: PaO 2 /FiO 2 < 100 mmhg) B. Minute Ventilation: VE CORR > 10L/min C. Radiographs: CXR with all 4 quadrants showing pulmonary edema D. Ventilator Pressures: P plat > 25 cm H 2 O E. Compliance: CRS < 40mL/cm H 2 O
Question 1 The Berlin Definition of Severe ARDS includes assessment of which of the following? A. Oxygenation: PaO 2 /FiO 2 < 100 mmhg) B. Minute Ventilation: VE CORR > 10L/min C. Radiographs: CXR with all 4 quadrants showing pulmonary edema D. Ventilator Pressures: P plat > 25 cm H 2 O E. Compliance: CRS < 40mL/cm H 2 O
Proposed New ARDS Definition (Berlin, 2011) ARDS Definition Task Force, JAMA 2012 Jun 20; 307 (23): 25 26 3 In absence of known predisposing risk factor* or not fully explained, assessment for cardiac failure required. Criteria for additional severity of disease did not enhance model and dropped from final definition *Pneumonia, aspiration, inhalation, pulmonary contusion, drowning Sepsis, transfusion, trauma, pancreatitis, noncardiogenic shock, drug overdose
Severity of baseline hypoxemia is associated with mortality in ARDS ARDS Definition Task Force, JAMA 2012 Jun 20; 307 (23): 25 26 33
Despite therapy, some patients will develop refractory hypoxemia
What do we actually think we know? Lower tidal volume ventilation with pressure limitation is good Correction of hypoxia is not a good surrogate for mortality * * ARDSnet NIH NHLBI ARDS Clinical Trials Network
What do we actually think we know? Ventilation with high airway pressures is bad
Treatment paradigm in ARDS Intensive Care Medicine (2012) 38:1573-1582
HFOV
Can We Reduce VILI Further?
HFOV Setup P AW Settings delta P (Power) Frequency Bias Flow, I:E
Pressure-Time Curve P r e s s u r e Time CMV HFOV
Targeting Lung Recruitment V o l u m e HFO CMV Pressure Lower Inflection Point Upper Infection Point
High Frequency Oscillation Theoretically ideal for lung protection Case series suggest safety RCTs suggest lower mortality relative risk 0.77, p = 0.03 outdated ventilation strategies CASE SERIES Fort et al. 1997 Mehta et al. 1997 p=0.057 30 d Claridge et al. 1999 Anderson p=0.078 et 90 al. d 2002 David et al. 2003 Carlotto et al. 2004 Mehta et al. 2004 Pach et al. 2006 Finkielman et al. 2006 Weiler et al. 2006 Derdak et Adhikari al. AJRCCM et al. 2009 2002
Question 2 Which of the following is not true regarding High Frequency Oscillatory Ventilation (HFOV)? A. Early initiation of HFOV in ARDS is associated with increased survival B. Decreased Hertz (decreasing frequency) will increase minute ventilation C. Improvements in oxygenation may be seen within six hours of therapy D. Sedation and neuromuscular blockade use are increased with HFOV
Question 2 Which of the following is not true regarding High Frequency Oscillatory Ventilation (HFOV)? A. Early initiation of HFOV in ARDS is associated with increased survival B. Decreased Hertz (decreasing frequency) will increase minute ventilation C. Improvements in oxygenation may be seen within six hours of therapy D. Sedation and neuromuscular blockade use are increased with HFOV
OSCILLATE Oscillation for Acute Respiratory Distress Treated Early CIHR/CCC Trials Group OSCILLATE trial Target sample size of 1200; terminated early after 548 enrolled for trend towards harm Ferguson ND, et al, NEJM 2013;3688 (9) 795-805
OSCAR High Frequency Oscillation in ARDS UK Trials Group OSCAR trial Enrolled 795 patients, no difference between HFOV and control groups Young D, et al, NEJM 2013;3688 (9) 806-813
Research Question For critically ill adults with ARDS, does the early application of high frequency oscillation reduce hospital mortality compared to a high-peep, low tidal volume ventilation strategy that incorporates HFO exclusively as rescue therapy? Target: 1200 adults with moderate-severe ARDS Acute respiratory failure PaO 2 /FiO 2 < 200 (standardized hypoxemia evaluation) Bilateral airspace disease on CXR Not attributed primarily to circulatory overload
Oxygenation Protocols Control FiO 2 0.3 0.4 0.4 0.4 0.4 0.4 0.5 0.5 0.6 0.7 0.8 0.8 0.9 1.0 PEEP 5-10 10 12 14 16 18 18 20 20 20 20 22 22 22-24 HFO FiO 2 0.4 0.4 0.4 0.4 0.5 0.6 0.6 0.6 0.7 0.8 0.9 1.0 1.0 mp AW 20-24 26 28 30 30 30 32 34 34 34 34 34 36-38 88% < SpO 2 < 93% 55 mm Hg < PaO 2 < 80 mmhg
Patients July 2007 through August 2012 (1 year hiatus) Began in 12 pilot centres - expanded to total 39 centres Canada; United States; Saudi Arabia; Chile; India (Mexico; UK; Australia; France) The Steering Committee terminated the trial on recommendation from the DMC on August 29, 2012 Following the 500-patient safety analysis 548 of planned 1200 patients randomized
Survival Curve
Cointerventions
Conclusions HFOV as used in the OSCILLATE trial does not improve survival and is likely harmful compared with a high PEEP, low tidal volume conventional strategy allowing HFOV only as rescue therapy
Rescue Strategies in ARDS? HFOV as Rescue for Severe ARDS
Prone Positioning
Question 3 Prone Positioning in adult patients with ARDS is associated with: A. Increased radiographic edema B. Reduced pressure ulcer rates C. Increased ventilator associated pneumonia rates D. Reduced mortality in patients with severe hypoxemia
Question 3 Prone Positioning in adult patients with ARDS is associated with: A. Increased radiographic edema B. Reduced pressure ulcer rates C. Increased ventilator associated pneumonia rates D. Reduced mortality in patients with severe hypoxemia
ARDS Bilateral patchy opacities Baby Lung Sitting on Top of a Consolidated Lung Posterior dependent lung consolidation Difficult to recruit
CT Imaging prior to Prone Position Posterior Dependent Atelectasis and Edema
PROSEVA (Proning Patients with Severe ARDS) Guerin C, et. al, NEJM, 368(23): 2159-68 June 6, 2013
PROSEVA - Study Overview Placing patients who require mechanical ventilation in the prone rather than the supine position improves oxygenation Enrolled Early Severe ARDS (P/F < 150 mm Hg on FiO 2 > 0.6, PEEP > 5 cm H 2 O, within 36 hours of onset) Prone 16 hours per day until improvement in supine position, mean 4.4 sessions per patient
PROSEVA: Enrollment, Randomization, and Follow-up of the Study Participants -Over 50,000 admissions -3,445 with ARDS ~2,000 not screened ~1,500 screened 576 eligible ~474 enrolled (13.7%) Guérin C et al. N Engl J Med 2013;368:2159-2168
Prone Positioning
Prone Position Techniques Vollman Prone Positioner Rotoprone Therapy System (KCI, USA)
Univ. Michigan Prone Method 4 people 2 sheets Easy to do Easy to teach Quick Easy access to patient
PROSEVA Probability of Survival from Randomization to Day 90 Guérin C et al. N Engl J Med 2013;368:2159-2168
PROSEVA C est possible? Incredible effect size - Day 28 and Day 90 Adjusted and Unadjusted Mortality OR 0.39 to 0.48 with proning - Majority of patients in both groups received neuromuscular blockade Guérin C et al. N Engl J Med 2013;368:2159-2168
PROSEVA - Conclusions In this trial, the investigators found a benefit with respect to all-cause mortality with this change in body position in patients with severe ARDS In patients with severe ARDS, early application of prolonged prone-positioning sessions significantly decreased 28-day and 90-day mortality Guérin C et al. N Engl J Med 2013;368:2159-2168
Rescue Strategies in ARDS Prone Position as Early Treatment or Rescue for Severe ARDS