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[临床决策]:ECMO治疗重症ARDS选项2:继续目前治疗
2018年09月29日 临床话题, 模拟诊室 暂无评论

CLINICAL DECISIONS

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome

Michael Y. Mi, Michael A. Matthay, and Alan H. Morris

N Engl J Med 2018; 379:884-887

DOI: 10.1056/NEJMclde1804601

Continue Current Treatment with Other Therapies

Alan H. Morris, M.D.

The decision to use ECMO for Mr. Jackson raises difficult issues that include both physician overconfidence in ECMO and the credibility of study results. Our first obligation is to ensure safety and protect patients from harm. We should then maximize the probability of a favorable outcome for the patient. It is clear that iatrogenic and avoidable harm is a serious medical problem. It is also clear that we lack evidence for many clinical decisions. Some researchers argue that much, if not most, of the published evidence that we bring to bear during clinical decision making is incorrect.7

Subjective judgment and willingness to offer unproven treatments contribute to much unwarranted variation in care.8 Dramatic interventions are difficult to resist. After all, if the patient seems to be dying, should we not do something? The challenge is to demonstrate with confidence that the “something” does more good than harm.9,10 This is a daunting challenge. The 2017 guideline from the American Thoracic Society, European Society of Intensive Care Medicine, and Society of Critical Care Medicine on mechanical ventilation for adults with ARDS states, “Additional evidence is necessary to make a definitive recommendation for or against the use of ECMO in patients with severe ARDS.”11 ECMO is invasive, costly, and dangerous, even though the technology has advanced rapidly. Until ECMO clearly produces a credible benefit that outweighs its risks in patients with ARDS, its use should be restricted to well-designed, rigorous scientific studies that will produce credible outcome results.

The EOLIA trial is the latest addition to the literature. Proponents of ECMO will conclude from the EOLIA trial that ECMO was probably beneficial (results regarding a secondary end point were better with ECMO); however, although the results with respect to the primary end point of 60-day mortality will suggest to some readers a benefit with respect to patient outcome, the difference between the groups was neither statistically significant (P=0.09) nor highly credible. Among the patients who were assigned to the control strategy (mechanical ventilation only), 28% were considered to have treatment failure and crossed over to receive ECMO support as rescue therapy. The introduction of ECMO in these patients was decided by the treating physician. Although some guidance was provided by the EOLIA study protocol, we cannot know how the treating physicians made these judgments; their reasoning was not captured. Since clinicians identify patients unequivocally expected to die with only approximately 85% accuracy,12 one expects that some of these “rescued” patients in the EOLIA trial might have lived with continued mechanical-ventilation-only treatment. A change in survival of a few patients would influence the results of the EOLIA trial. This experimental design flaw reduces the credibility of the survival result in patients treated with mechanical ventilation only. “Crossover” indicates the treating physicians’ bias toward ECMO as a beneficial therapy at the time of crossover, although the evidence for ECMO benefit in ARDS is tenuous. This design flaw thus reduces the credibility of favorable interpretations of EOLIA study results.

I believe that once physicians have carried out all treatments known to be beneficial (the most important of which is the lung-protective mechanical-ventilation strategy that targets tidal volumes of 6 ml per kilogram of predicted body weight), they have discharged their ethical and professional obligations to patients. The use of treatments, like ECMO, that have considerable dangers and that might harm more than help should be restricted to scientifically rigorous clinical investigations that are designed to produce maximally credible results. They should not be used widely in clinical care, and I would not introduce ECMO support for Mr. Jackson.

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