ECMO without a ventilator: what fails, and how quickly

Design

International retrospective cohort, 14 centres in 8 countries, 2015-2024

Population

307 adults with acute respiratory distress syndrome on extracorporeal membrane oxygenation without invasive ventilation (113 primary awake, 194 extubated on support)

Primary outcome

Mortality 90 days after initiation of extracorporeal support

Effect

90-day mortality 30.1 per cent awake vs 14.9 per cent extubated; strategy failure 40.7 vs 24.2 per cent, associated with death (HR 5.95, 95 per cent CI 2.63-13.46 and 7.67, 3.44-17.11)

Fourteen centres across eight countries pooled 307 adults with acute respiratory distress syndrome managed on extracorporeal membrane oxygenation without invasive ventilation between 2015 and 2024 - 113 started awake to avoid intubation, and 194 extubated while on support.

Ninety-day mortality was 30.1 per cent in the primary awake group and 14.9 per cent in the extubated group, but these are different patients selected for different reasons and the figures should not be read against each other. What is comparable is strategy failure: 40.7 per cent of the awake group and 24.2 per cent of the extubated group failed the strategy, most within the first 10 days, and failure was strongly associated with death at 90 days in both (hazard ratio 7.67, 95 per cent CI 3.44 to 17.11 in the extubated group; 5.95, 2.63 to 13.46 in the awake group). The commonest reason for failure in both was worsening respiratory failure; after that, agitation and delirium in the awake group and inability to clear secretions in the extubated group.

The practical content is in those two secondary failure modes, because both are addressable. A programme attempting this needs a sedation and delirium plan that works in a patient who must stay awake and cannulated, and a secretions plan - physiotherapy, cough assist, bronchoscopy access - for a patient who has just lost their tube. And the first 10 days are when it is decided, which is when the staffing intensity has to be there.

• Plan for agitation and delirium explicitly before starting a patient awake on support.
• Have a secretion clearance pathway ready before extubating anyone on extracorporeal support.
• Concentrate staffing and senior review in the first 10 days, when almost all failures happened.
• Do not compare the two groups' mortality; selection differs and this is a retrospective cohort.
• Cannulate earlier where the strategy is intended - longer time from ICU admission to cannulation predicted death in the awake group.

The statistics, in plain English

Hazard ratios of 5.95 and 7.67 with intervals from 2.6 to 17.1 are very large and very imprecise, which is what happens when a small cohort is split by an outcome that is itself close to the endpoint - patients whose strategy fails are deteriorating, so the association partly restates the deterioration. This is a retrospective cohort of highly selected patients at experienced centres, so the mortality figures cannot be transferred to a unit starting out, and there is no comparison group managed conventionally.

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