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470 PART 4: Pulmonary Disorders

and the acute respiratory distress syndrome. N Engl J Med.
2000;342:1301. • VV-ECMO is now being used as a therapeutic option to bridge
• Ashbaugh DG, Bigelow DB, Petty TL, Levine BE. Acute respiratory patients with advanced lung disease to lung transplantation,
avoiding the use of mechanical ventilation and allowing aggres-
distress in adults. Lancet. 1967;2:319. sive physical rehabilitation.
• Bernard GR, Reines HD, Brigham KL, et al. The American • A new adult ARDS ECMO multicenter clinical trial has been
European consensus conference on ARDS: definitions, mecha- initiated, entitled ECMO to rescue Lung Injury in severe ARDS
nisms, relevant outcomes and clinical trials coordination. Am J (EOLIA, Alain Combes MD, Principal Investigator, France).
Resp Crit Care Med. 1994;149:818.
• Eisner MD, Thompson T, Hudson LD, et al. Efficacy of low tidal • ECMO is a complex critical care organ support system, and
volume ventilation in patients with different clinical risk factors requires an experienced and dedicated team, appropriate equip-
for acute lung injury and the acute respiratory distress syndrome. ment, and institutional commitment and leadership.
Am J Respir Crit Care Med. 2001;164:231. • The current evidence supports the transfer of patients with severe
• Gajic O, Dabbagh O, Park PK, et al. Early identification of patients hypoxemia and ARDS to institutions with significant experience in
at risk of acute lung injury: evaluation of the lung injury prediction ARDS management and with ECMO capabilities.
score in a multicenter cohort study. Amer J Respir Crit Care Med.
2011;183:462.
• Herridge MS, Tansey CM, Matté A, et al. Functional disability
5 years after acute respiratory distress syndrome. N Engl J Med. EXTRACORPOREAL LUNG SUPPORT
2011;364:1293.
• Hopkins R, Weaver L, Pope D, et al. Neuropsychological sequelae Extracorporeal membrane oxygenation (ECMO) is an advanced treat-
and impaired health status in survivors of severe acute respiratory ment option for patients with severe respiratory failure and severe
1-6
distress syndrome. Am J Respir Crit Care Med. 1999;160:50. hypoxemia. The goal of ECMO for lung support is to avoid the use
• Rubenfeld GD, Caldwell E, Peabody E, et al. Incidence and out- of high levels of oxygen and high airway pressures that may be neces-
sary to support oxygenation and ventilation with mechanical ventila-
comes of acute lung injury. N Engl J Med. 2005;353:1685. tion in severe hypoxemia and acute respiratory failure. Nearly 20%
• Ware LB, Matthay MA. The acute respiratory distress syndrome. of acute respiratory distress syndrome (ARDS) patients die of severe
N Engl J Med. 2000;342:1334. hypoxemia. 7
ARDS is associated with pathologically complex changes in the lung
manifested by an early exudative phase followed by proliferative and
fibrotic phases. The acute inflammatory state leads to increased capil-
8
REFERENCES lary permeability and accumulation of proteinaceous pulmonary edema,
Complete references available online at www.mhprofessional.com/hall leading to hypoxemia. Hypoxia may further aggravate lung injury, and
treatment strategies therefore focus on improvement of oxygenation and
correction of the underlying problem. 9
Mechanical ventilatory support can be injurious and lead to addi-
CHAPTER Extracorporeal Lung tional lung injury when used at the extremes of pulmonary physiology,
10
53 Support a concept that has been termed ventilator-induced lung injury (VILI).
There are a number of mechanisms that can lead to the development
Lena M. Napolitano of VILI, including barotrauma, diffuse alveolar injury due to overdis-
tension (volutrauma), injury due to repeated cycles of recruitment/
derecruitment (atelectrauma) and the most subtle form of injury due to
the release of local mediators in the lung (biotrauma). 11
KEY POINTS
The goal of ECMO therapy is to minimize VILI while allowing addi-
• Extracorporeal membrane oxygenation (ECMO) can be used to tional time to treat the underlying disease and to permit recovery from
12
provide support to selected patients with severe acute respiratory acute injury or illness. Proper selection of patients for ECMO therefore
failure and severe hypoxemia. involves determination of whether the pulmonary disease process is
• The two major ECMO modalities are veno-venous (VV) and reversible. ECMO for adult respiratory support continues to increase in
veno- arterial (VA), but most cases of extracorporeal lung support the United States and worldwide. 13
use VV-ECMO. ECMO is a complex critical care organ support system, and requires
• The prospective, randomized Adult ECMO study (CESAR trial) an experienced and dedicated team, appropriate equipment, and insti-
tutional commitment and leadership. The current evidence supports
14
reported a 31% improved outcome in patients transported to a spe- the transfer of patients with severe hypoxemia and ARDS to institutions
cialized center for possible ECMO (63% vs 47% survival without with significant experience in ARDS management, and with ECMO
disability; relative risk 6-month death or severe disability 0.69, 95% capabilities, to allow further expert evaluation and treatment. 15
CI 0.05-0.97; RR death 0.73, 95% CI 0.52-1.03).
• Significant adverse events and complications can occur during
ECMO, most related to hemorrhage, but are becoming less common RESPIRATORY CONDITIONS REQUIRING ECMO
with improved technology and reduced anticoagulation requirements. ECMO is used in a number of respiratory conditions that cause
• ECMO is used in patients with severe hypoxemia related to ARDS, acute respiratory failure and severe hypoxemia (see Table 53-1). The
2009 Influenza A (H1N1)–associated ARDS, trauma, and pulmo- most common indication for ECMO for lung support is severe life-
nary embolus. threatening hypoxemia associated with inadequate tissue oxygenation,
• Survival to discharge in adult patients receiving ECMO for most commonly in patients with severe ARDS. Although oxygenation
respiratory failure is 52% from the Extracorporeal Life Support itself is not clearly predictive of poor outcomes in ARDS, there is
Organization (ELSO) registry. increasing evidence that a lower Pa O 2 /Fi O 2 ratio is predictive of death,
especially if the hypoxemia persists over time. 16-24

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