Airways-2

CPR2As we wait for the new 2015 guidelines for resuscitation later this year, the protocol for a major study which should be completed in time for inclusion in the evidence review for the 2020 guidelines is now available on-line.

‘Project portfolio HTA 12/167/102, Cluster randomised trial of the clinical and cost effectiveness of the i-gel supraglottic airway device versus tracheal intubation in the initial airway management of out of hospital cardiac arrest (Airways-2)’

Just over a year ago I uploaded a blog post entitled, REVIVE airway study – clinical outcomes and future plans. As well as reviewing REVIVE 1, the article discussed the future plans for REVIVE 2, now called AIRWAYS-2. Publication is expected in 2019, which if realised, will allow the study to be considered as part of the 2020 ILCOR Scientific Evidence Evaluation and Review System (SEERS) process.

Why is this trial important? Well, AIRWAYS-2 is an attempt to provide the type of high quality evidence called for back in 2009 by Nolan and Lockey in an editorial entitled, ‘Airway management for OHCA – more data required’. In this editorial, the authors commented that, ‘Virtually all the existing data relating to the use of SADs in cardiac arrest are derived from low-level studies. There is an urgent need for high-quality randomised controlled trials of the use of SADs for CPR.’ However, such studies are not easy to perform in the pre-hospital setting.

The AIRWAYS-2 trial summary confirms that:

 ‘There is real uncertainty amongst paramedics and experts in the field about the best method to ensure a clear airway during the early stages of OHCA. We therefore propose to undertake a large research study to determine whether intubation or the best available SAD (called the i‐gel) gives the best chance of recovery following OHCA.’

Paramedics from the following four English NHS ambulance services will participate:

  • South Western Ambulance Service NHS Foundation Trust (SWAST)
  • East of England Ambulance Service NHS Trust
  • East Midlands Ambulance Service NHS Trust
  • Yorkshire Ambulance Service NHS Trust

 As randomisation by patient is impractical in the pre-hospital emergency setting, randomisation will be by paramedic. The trial population will include adults who have suffered an OHCA that is not due to trauma. Patient exclusion criteria includes an estimated weight <50kg and a mouth opening of <2cm.

The trial intervention control group is the current standard care pathway: Tracheal intubation. The Intervention group (i-gel) is referred to as follows:

 ‘Because of its speed and ease of insertion, and the fact that it does not require a cuff to be inflated, the i‐gel has emerged as the preferred SAD for use during OHCA in Europe.’

 The aim and objectives of the study are confirmed as follows:

 Aim:

  • To determine whether the i‐gel, a second‐generation SAD, is superior to tracheal intubation in non-traumatic OHCA in adults, in terms of both clinical and cost effectiveness.

 Objectives:

  1. To estimate the difference in the primary outcome of modified Rankin Scale (mRS) at hospital discharge between groups of patients managed by paramedics randomised to use either the i‐gel or intubation as their initial airway management strategy following OHCA.
  2. To estimate differences in secondary outcome measures relating to airway management, hospital stay and recovery at 3 and 6 months (see section 4.6.2) between groups of patients managed by paramedics randomised to use either the i‐gel or intubation.
  3. To estimate the comparative cost effectiveness of the i‐gel and intubation, including estimating major in hospital resources and subsequent costs (length of stay, days of intensive and high dependency care, etc.) in each group.

The secondary outcomes include initial ventilation success, regurgitation/aspiration, the sequence of airway ventilations delivered and return of spontaneous circulation (ROSC). Additional secondary outcomes will be recorded for patients who survive to hospital and to hospital discharge, including for the latter, Modified Rankin scale and quality of life at 3 and 6 months following OHCA.

It is stated that a 2% improvement in the proportion of patients achieving a good clinical outcome would be clinically significant. This study will also include an economic evaluation. It is estmated that 1,300 paramedics will participate and the cost will be over £2 million.

An Airways-2 web-site is now up and running, and includes an overview of the trial, details regarding the study team and an FAQ page.

Four years may seem a long time to wait and there is always the risk that by the time the results are ready to be published, the landscape of airway management during cardiac arrest has changed. However, it would be difficult to factor out such a risk, and AIRWAYS-2 can be seen as a significant attempt to provide the high level data regarding management of the airway during the initial stages of cardiac arrest we all want to see.

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How long is long enough for hospital resuscitation?

It was a pleasant surprise last week to hear Jerry Nolan being interviewed on the Today programme on BBC Radio 4, regarding a new study just published online in The Lancet entitled – ‘Duration of resuscitation efforts and survival after in-hospital cardiac arrest: an observational study’.

It is currently unknown how long resuscitation should be continued for in-hospital cardiac arrests, whether the length of resuscitation attempts varies between hospitals, and whether patients at hospitals who attempt resuscitation for longer periods of time have higher survival rates.

This observational study, using the largest known database of in-hospital cardiac arrests, the AHA ‘Get with the Guidelines – Resuscitation Registry (formerly known as the National Registry of Cardiopulmonary Resuscitation – NRCPR), identified over 64,000 patients between 2000 and 2008 from 435 USA hospitals who had a cardiac arrest. The length of time resuscitation was attempted in patients who did not survive was used as a measure of the hospital’s overall tendancy for continuing CPR for longer time periods. The primary endpoints were immediate survival with ROSC and survivial to hospital discharge.

The results showed a variation between hospitals for the duration of resuscitation attempts. They also found that patients at hospitals who attempted resuscitation for longer time periods were more likely to survive to hospital discharge. Multilevel regression models were used to assess the relationship between the length of resuscitation efforts and risk-adjusted survival. The authors concluded that their findings suggested ‘efforts to systematically increase the duration of resuscitation could improve survival in this high risk population’.

Jerry Nolan and Jasmeet Soar provide further background and context to this study in the article ‘Duration of in-hospital resuscitation: when to call time?’, also published in The Lancet.