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CHAPTER 53: Extracorporeal Lung Support 479

Aetna considers ECMO and extracorporeal life support (ECLS) medi-
TABLE 53-6 ECMO Human RCTs
cally necessary for children and adults with any of the following diagnoses
Clinical Trial Critiques when the risk of death is very high despite optimal conventional therapy.
VA-ECMO + ventilation • 90 patients, 9 US centres, 1974 -1977 1. Acute respiratory distress syndrome (ARDS)
and ventilation only in • Survival <10% in both arms
Severe Acute Respiratory • Criticisms: 2. As a short-term (ie, hours to a few days) bridge to heart, lung or
Failure: A Randomized 1. VA-ECMO used (prone to microthrombi in lungs); heart-lung transplantation
Prospective Study standard for ARDS is VV-ECMO 3. Following heart surgery to ease transition from cardiopulmonary
Zapol et al. 55 2. High anticoagulation and bleeding complications bypass to ventilation
3. High-pressure ventilation used even 4. Non-necrotizing pneumonias (both bacterial and viral)
during ECMO
4. Mean duration of ventilation prior to ECMO 5. Primary graft failure after heart, lung or heart-lung transplantation
was 9 days—ELSO registry data show increasing 6. Pulmonary contusion
mortality with pre-ECMO duration 7. Refractory pediatric septic shock
of mechanical ventilation 8. Other reversible causes of respiratory or cardiac failure (eg, myocar-
• Little ECMO experience, varying technique in different ditis) that is unresponsive to all other measures.
centers
Randomized trial of PCIRV and • PCIRV vs ECCO R Adult RCT Aetna considers ECMO for children and adults experimental and
2
ECCO R in ARDS • 40 patients, severe ARDS (Pa O 2 /Fi O 2 ratio investigational for all other indications because of insufficient evidence
2
Morris AH et al. 55 63 mm Hg) of its safety and effectiveness.
• One US center (LDS Hospital, Salt Lake City, Utah) ■
• 1987-1991 EOLIA ECMO TRIAL
• 33% 30-day survival in 21 patients ECCO R + LFPPV A multicenter ECMO trial in adult severe ARDS is just underway,
2
• 42% 30-day survival in 19 patients PCIRV entitled ECMO to rescue Lung Injury in severe ARDS (EOLIA, Alain
• P = 0.8, no significant difference Combes MD, Principal Investigator, France). The inclusion criteria
• Little previous experience in center with technique in and randomization scheme and primary outcome measure are in
humans Figure 53-10. The primary endpoint is to achieve, with ECMO, sig-
• High-pressure ventilation before and during ECCO R nificantly lower mortality on day 60. This study aims to enroll patients
2
(PEEP >20, peak inspiratory pressures 45-55 cm H O) with severe ARDS, and the control arm has specific guidelines for
2
• Frequent severe bleeding complications (leading to lung-protective mechanical ventilation with assist-controlled ventilation
discontinuation of ECCO R in 7/19 cases) mode, V set at 6 mL/kg of ideal body weight and PEEP set so as not to
2 t
CESAR Trial • ECMO vs standard care (conventional ventilation) exceed a plateau pressure of 28 to 30 cm H O. In the case of refractory
2
Peek GJ et al. 52 adult RCT hypoxemia, the usual adjunctive therapeutics can be used: inhaled NO,
• 180 patients with severe but potentially reversible prone position, HFOV, and/or almitrine infusion. A cross-over option
acute respiratory failure to ECMO will be possible in the case of refractory hypoxemia defined
• Only 76% of randomized patients received ECMO as blood arterial saturation Sa O 2 <80% for >6 hours, despite mandatory
• Lung-protective low-tidal-volume ventilation was not use of recruitment maneuvers, and inhaled NO/prostacyclin and if tech-
mandated in standard care cohort; only 70% nically possible a test of prone position, and only if the patient has no
received this irreversible multiple organ failure and if the physician in charge of the
• Greater 6-month survival without disability in ECMO patient believes that this could actually change the outcome.
cohort (RR 0.69, 95% CI 0.05-0.97)
• Difficult to separate effect of ECMO vs experienced ECMO AND 2009 INFLUENZA A (H1N1) SEVERE ARDS
team in a single specialized center
Severe respiratory failure (including acute lung injury [ALI]) and
None of these studies compares ECMO to lung-protective ventilation. ARDS in patients with 2009 H1N1 Influenza pulmonary infection
57
has been described worldwide. 58-65 A common feature of these patients
is severe hypoxemia, ARDS, and an inability to achieve adequate oxy-
bleeding complications, and used high-pressure ventilation during genation with conventional ventilation modalities commonly used in
extracorporeal support. 56 the treatment of severe ARDS. In addition, high case fatality rates have
The third ECMO RCT, the CESAR trial, discussed in detail above, been reported, with multiple organ failure as the leading cause of death.
was critiqued for two reasons: (1) only 76% of the randomized patients Our case series of ICU patients with severe 2009 H1N1 Influenza
in the ECMO cohort received ECMO, and (2) lung-protective low-tidal- virus infection and ARDS in Michigan reported in June 2009 docu-
volume ventilation was not mandated in the standard care cohort, and mented the use of a number of rescue therapies for the treatment of
only 70% received it. Furthermore, it is difficult to separate the effect severe hypoxemia in these patients. 57
of ECMO versus the ICU care provided by an experienced specialized Most patients who died from 2009 H1N1 Influenza did so as a result
team in a single specialized center with regard to the improved outcomes of unrelenting hypoxemic respiratory failure. Hypoxemia was identified
seen in the ECMO cohort. Finally, none of these three RCTs compared as an independent risk factor for mortality in the report from Mexico,
ECMO with a lung-protective pressure- and volume-limited mechani- documenting a median Pa O 2 : Fi O 2 ratio of 164 (range 87-250) in patients
cal ventilation strategy, which has now become the standard of care for who survived (n = 11) compared to 53 (range 46-107) in patients who
patients with ARDS. Given these limitations, a new ECMO adult trial is died (n = 7), with hazard ratio for death 0.95 (95% CI 0.91-0.99, p value
being initiated. 0.02). Consideration of rescue therapies for refractory hypoxemia is
Based on the published evidence to date, insurance companies have therefore fully warranted. 66
established clinical policies for the “medically necessary” use of ECMO ECMO support has been used as a treatment for severe respiratory
in children and adults. ECMO for Children and Adults: http://www. failure due to 2009 H1N1 Influenza in the United States and world-
57
aetna.com/cpb/medical/data/500_599/0546.html. wide, but US multicenter data on its efficacy is not yet available. The

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