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12/6/2017
1
An Evidence-Based Approach to Mechanical
Ventilation of the Patient with Hypoxemic
Respiratory Failure
Dean Hess
Disclosures
• Philips Respironics
• Ventec Life Support
• Daedalus Enterprises
• Jones and Bartlett
• McGraw-Hill
• UpToDate
• American Board of Internal Medicine
12/6/2017
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Hypoxemic Respiratory Failure: ARDS
• What about noninvasive respiratory support?
• What tidal volume should be selected?
• How to set PEEP?
• What about permissive hypercapnia?
• How to address refractory hypoxemia?
• How do clinical practice guidelines inform our practice?
What About Noninvasive Respiratory Support?
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PaO2/FIO2 < 150 PaO2/FIO2 ≥ 150
Am J Respir Crit Care Med 2017;195:67
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What Tidal Volume Should Be Selected?
N Engl J Med 2000;342:1301
ARDS Network Study
• 861 patients with ALI/ARDS
– 12 mL/kg ideal body weight
– 6 mL/kg ideal body weight
• Pplat ≤ 30 cm H2O
• Tidal volume decreased to 4 mL/kg for Pplat ≤ 30 cm H2O; increased to 8
mL/kg for asynchrony or acidosis provided Pplat ≤ 30 cm H2O
• Volume-control continuous mandatory ventilation
• 25% reduction in mortality for smaller tidal volume
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18% relative increase in mortality for each 1 mL/kg IBW increase in tidal volume.
JAMA 2016;315:788
Fewer than two-thirds of
patients with ARDS received a
tidal volume ≤8 mL/kg IBW.
Plateau pressure was
measured in only 40%.
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Crit Care Med 2015;43:2155
Alveolar stretch (PL) = Palv - Ppl
-18 cm H2O
PC
“It is important to ascertain whether the spontaneously
breathing patient in fact has a high respiratory drive
and has adopted a ventilatory pattern which will lead to
subsequent lung injury. This is not a trivial matter.”Brochard, Slutsky, Pesenti. Am J Respir Crit Care Med 2017;195:438
“Patient-self inflicted lung injury (P-SILI)”
- More likely with PCV.
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How to Set PEEP?
Gattinoni, N Engl J Med 2006;354:1775
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Higher vs. Lower PEEP
• VT 6 mL/kg PBW; 2 PEEP levels• ALVEOLI (Brower, N Engl J Med 2004;351:327)
– Oxygenation better with higher PEEP– Stopped early at 549 patients for futility
• LOVS (Meade, JAMA 2008;299:637)– Less hypoxemia and use of rescue therapies– No significant difference in hospital mortality
• EXPRESS (Mercat, JAMA 2008;299:646)– Improved lung function, reduced duration of
mechanical ventilation and organ failure– No significant difference in mortality
0
10
20
30
Lower PEEP
Higher PEEP
6 mL/kg
Ppl
at/P
EE
P (
cm H
2O)
6 mL/kg
6 mL/kg
Injury >
Benefit
Benefit >
Injury
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Ann Am Thorac Soc 2017;14:S297
JAMA 2010;303:865
Su
rviv
al
Su
rviv
al
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How to Set PEEP• Gas exchange
– Oxygenation: PEEP/FIO2 tables– Dead space
• Respiratory mechanics– Compliance (lowest driving pressure)– Pressure-volume curve– Stress index– Transpulmonary pressure (esophageal balloon)
• Imaging– Chest CT– EIT– Ultrasound
• “Best PEEP” does not exist.
• “Better PEEP” is a reasonable compromise among oxygenation,
hemodynamic status, and intra-tidal opening and closing.
– 15 - 20 cm H2O in severe ARDS
– 10 - 15 cm H2O in moderate ARDS
– 5 - 10 cm H2O in mild ARDS
Curr Opin Crit Care 2015, 21:50
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September, 2017
ΔP = Pplat - PEEP
Amato, N Engl J Med 2015;372:747
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What About Permissive Hypercapnia?
Hypercapnia and Mortality
Moderate or Severe ARDS
Nin, Intensive Care Med 2017;43:200
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How To Address Refractory Hypoxemia?
Refractory Hypoxemia
• Evidence supports
– Neuromuscular blockade
– Prone position
• Weak evidence
– Extracorporeal support (ECMO)
– Airway pressure release ventilation (APRV)
• Evidence does not support
– Inhaled pulmonary vasodilator: nitric oxide or prostacylin
– High frequency oscillatory ventilation
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Narendra, Hess, et al. Chest 2017;152:867
How Do Clinical Practice Guidelines
Inform Our Practice?
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Am J Respir Crit Care Med 2017;195:1253
Guidelines For:
• Strong
– Mechanical ventilation using tidal volumes 4 to 8 mL/kg PBW and
plateau pressure <30 cm H2O.
– Prone positioning for more than 12 h/d in severe ARDS.
• Conditional
– Higher PEEP in patients with moderate or severe ARDS.
– Recruitment maneuvers in patients with moderate or severe ARDS.
Am J Respir Crit Care Med 2017;195:1253
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Guideline Against:
• Routine use of high-frequency oscillatory ventilation in
patients with moderate or severe ARDS.
• Additional evidence is necessary to make a definitive
recommendation for or against the use of ECMO in patients
with severe ARDS.
No Recommendation
Am J Respir Crit Care Med 2017;195:1253
Setting the Ventilator
Ventilator-InducedLung Injury Gas Exchange
Patient Comfort Hemodynamics