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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

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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