CESAR Trial: Extracorporeal Membrane Oxygenation Improves Survival in Patients With Severe Respiratory Failure

Emma Hitt, PhD

February 05, 2008

February 5, 2008 (Honolulu) — Extracorporeal membrane oxygenation (ECMO) increases survival among adult patients with severe but potentially reversible respiratory failure compared with conventional ventilatory support, according to findings from the Conventional Ventilation or ECMO for Severe Adult Respiratory Failure (CESAR) trial.

Lead clinical investigator Giles J. Peek, MD, FRCS, from the University of Leicester, Glenfield, United Kingdom, reported the findings of the trial here at a late-breaking session at the Society of Critical Care Medicine 37th Critical Care Congress.

"Use of ECMO results in 1 extra survivor for every 6 patients treated, so I would suggest to you that this is 'right care, right now,' " said Dr. Peek, making use of the society's slogan.

ECMO refers to the technique of providing both cardiac and respiratory support oxygen to patients by draining blood from the venous system and oxygenating it outside of the body. According to Dr. Peek, for patients with severe but potentially reversible respiratory failure, ECMO may increase the rate of survival without severe disability 6 months after randomization and may be cost-effective compared with conventional ventilatory support.

For the CESAR trial, patients were recruited from the ECMO center in Glenfield, Leicester, as well as from conventional treatment centers and referral hospitals from July 2001 to August 2006. An emergency inclusion protocol was also available for nontrial hospitals.

Patients had severe but potentially reversible respiratory failure and either a Murray score of 3.0 or more or uncompensated hypercapnia (pH < 7.2). Patients were excluded if they had prolonged high pressure of a fraction of inspired oxygen (FIO2) of 80% for more than 7 days and/or a contraindication to treatment.

The conventional treatment group mirrored standard clinical practice in the United Kingdom, with a low-volume ventilation strategy recommended. The primary outcome measure was death or severe disability 6 months after randomization and included deaths before hospital discharge if occurring after 6 months. Severe disability was defined as being both "confined to bed" and "unable to wash or dress oneself."

A total of 180 patients from 68 centers were randomly assigned to receive conventional ventilation (n = 90) or ECMO (n = 90). Of the 90 patients assigned to receive ECMO, 22 did not receive ECMO, most often because they improved without it. Patient characteristics were well matched between groups.

Of the patients randomly assigned to receive ECMO, 57 of 90 met the primary endpoint of survival or absence of severe disability at 6 months compared with 41 of 87 evaluable patients in the conventional ventilation group. This translated to a relative risk in favor of the ECMO group of 0.69 (95% confidence interval, 0.05 – 0.97; P = .03).

There was also a nonsignificant trend toward decreased deaths before 6 months in the ECMO group vs the conventional ventilation group (57 of 90 vs 47 of 87; P = .07). Patients in the conventional group died more quickly than in the ECMO group (5 vs 15 days). One ECMO-related death occurred, which was attributed to a cannulation problem.

Notably, a significant number of patients had failure of more than 3 organs in both groups (28 in the ECMO group and 27 in the conventional group), supporting the notion that ECMO can and should be used in the setting of multiple organ failure.

The median duration of ventilation before inclusion in the trial was approximately 35 hours in both groups, and the median duration of high-pressure ventilation in both groups was approximately 28 days.

The benefit of ECMO was seen regardless of several factors including hospital of trial entry, age, presence of hypoxia, duration of high-pressure ventilation,primary diagnosis at trial entry, and number of organs failed.

"The take-home message is that ECMO should be considered for most patients who cannot receive lung-protective ventilation and should be implemented as early as possible — before 7 days." Dr. Peek told Medscape Critical Care.

A limitation of ECMO is that it cannot be done in every hospital, he said. "Specific skills from a multidisciplinary team are needed, and there must be enough patients for skills to be maintained." He added that the findings of this study probably would extrapolate to the US population and other first-world countries.

"This has the potential to be a very practice-changing study," said Heidi J. Dalton, MD, from the Children's Hospital, Pittsburgh, Pennsylvania, who moderated the late-breaking session and specializes in pediatric ECMO.

According to Dr. Dalton, the role of ECMO is this setting has been controversial in the United States since a trial by the National Institutes of Health in the 1970s compared ECMO in adults vs conventional therapy and showed that patients did poorly in both groups. "However, the findings in this study have the potential to elevate the use of ECMO in the adult [intensive care unit] setting," she told Medscape Critical Care.

But Dr. Dalton pointed out that it was difficult to determine whether the benefit seen was caused by ECMO or a result of the critical care environment being better at Glenfield than at other centers. "More data on the patients treated conventionally are needed to properly compare the 2 approaches."

"I think the fear that a lot of us have with ECMO is that there is a learning curve, and it is not something that hospitals can implement without preparation," she said. "We need to focus on providing training and teach people how to deliver ECMO."

The trial was supported by the Health Technology Assessment program, the English National Specialist Commissioning Advisory Group, and the Scottish and Welsh Departments of Health. Dr. Peek and Dr. Dalton have disclosed no relevant financial relationships.

Society of Critical Care Medicine 37th Critical Care Congress: Late-breaking session. Presented February 3, 2008.

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