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.

REVIVE airway study – clinical outcomes and future plans

Since plans were first announced to conduct a randomised comparison of two second generation SADs to current practice in the initial airway management of out-of-hospital cardiac arrest (OHCA) in a UK ambulance service, the results have been eagerly anticipated. This can be no surprise given the paucity of high level evidence to confirm the best technique for maintaining an airway and providing ventilation in adults with cardiopulmonary arrest.

However, the primary objective of REVIVE was not to provide a definitive answer to the above question, but to assess the feasibility of the study design. If REVIVE proved the design was feasible, capable of establishing whether ventilation success can be achieved, and of measuring other key outcomes such as return of spontaneous ventilation and survival to hospital, then it would lay the foundation for a future full-scale study which might just provide us with the answer to the above question.

The REVIVE airway working group presented a poster at the International Conference on Emergency Medicine (ICEM) in Dublin in June last year entitled, ‘Early report of paramedic recruitment in the REVIVE-Airways study’. This confirmed the target of recruiting 150 randomised paramedics and stratification by experience and base station location had been successfully achieved.

Last month, in an abstract presented at the American Heart Association Resuscitation Science Symposium in Dallas, we had our first glimpse of the data related to the clinical outcomes. As this was a feasibility trial and not designed or powered to show clinically significant differences between each device or study arm, there was some discussion as to whether the clinical data should be released. However, the protocol published in the British Medical Journal (BMJ), suggests the original intention had always been to disseminate the clincial data to participants in the study and to the wider public via an open access web-site, appropriate conferences and medical journals.

A more comprehensive overview of the study results was presented at the UWE Conference & Exhibition Centre in Bristol on the 29th November. Speakers included Dr Jerry Nolan, Dr Jas Soar, Prof Jonathan Benger, Dr Matt Thomas, Dr Janet Brandling, Dr Sarah Voss and Mr Dave Coates.

The results showed no significant differences in important clinical outcomes between the use of a supraglottic airway (SAD) and usual practice (principally tracheal intubation) during OHCA. However, the trial was insufficiently powered to detect small differences in mortality. The i-gel® was superior to the LMA Supreme® on several measures, including compliance, adverse events and staff feedback. The investigators are proceeding to a large-scale trial of i-gel® versus tracheal intubation in OHCA.

For the record, the survival to hospital discharge was as follows:

     • i-gel® 10.3%
     • LMA Supreme® 8.0%
     • Usual practice 9.1%

     (p=0.73)

Survival to 90 days is shown below:

     • i-gel® 9.5%
     • LMA Supreme® 6.9%
     • Usual practice 8.6%

     (p=0.65)

Data was also presented on neurocognitive and quality of life outcomes, as well as successful device placement. There was also interesting data regarding the number of arrests attended by each paramedic (March 2012 to February 2013), which ranged from 0-11, with a mean of 3.6 arrests per paramedic. 15 paramedics did not attend any arrest during the study period. There were presentations confirming how the airway was actually managed in practice and feedback from the paramedics that participated in the study.

Successful aspects of REVIVE included proof of the feasibility of a cluster randomised trial of airway intervention in OHCA and the collection of valuable data to inform a full trial. It also demonstrated the strong support of paramedics and informed statistical calculations for a larger study. So, what next?

REVIVE 2

Professor Jonathan Benger, in a presentation entitled, ‘Further research: REVIVE 2’, confirmed the aims of REVIVE 2 as identifying differences in the primary outcome of modified Rankin Scale (mRS) at hospital discharge: good recovery (0-3) versus poor recovery/death (4-6) and differences in:

• mRS at 3 and 6 months following OHCA
• Quality of life at discharge, 3 months and 6 months
• Cognitive function at 3 and 6 months
• ROSC
• Length of stay
• Ventilation success, regurgitation and aspiration
• Loss of a previously established airway

Comparative cost effectiveness of the i-gel® and intubation, as well as the views and preferences of paramedics is also to be assessed.

It is intended the design will be a cluster randomised trial (by paramedic), with an airway algorithm for each arm. Clinical need will always take precedence and there will be an economic analysis, as well as patient and public involvement. An outline bid has been successful, and a full proposal is to follow (5th February 2014). It is intended for the trial to run for 45 months, from October 2014 to June 2018.

REVIVE 2 will need approximately 1,300 paramedics. This will probably require the inclusion of three or four large UK ambulance trusts. It is estimated the cost for REVIVE 2 will be £2 million. The investigators are ready to begin.

Four and a half years (probably 5 years before the results are reported) may seem a long time to wait for the conclusion of REVIVE 2, but given the lack of high level data currently available regarding the best airway device to use during the initial phase of OHCA, it will be worth the wait.

The i-gel SGA for prehospital airway management in a UK ambulance service

As previously reported on this blog page, the optimum method for management of the airway during cardiac arrest (CA) continues to be the subject of lively debate. The European Resuscitation Council (ERC) guidelines confirm that ‘There are no data supporting the routine use of any specific approach to airway management during cardiac arrest. The best technique is dependent on the precise circumstances of the cardiac arrest and the competence of the rescuer.’

With regard to the use of supraglottic airways (SADs) for CA, the call went out in an editorial entitled ‘Airway Management for out-of-hospital cardiac arrest – more data required’, published in 2009 in Resuscitation by Nolan and Lockey for high quality randomised controlled trials (RCTs) of the use of SADs for cardiopulmonary resuscitation (CPR). The REVIVE airways study process is an attempt to provide just such evidence by conducting a randomised comparison of the ventilation success of two 2nd generation supraglottic airways, i-gel® and the LMA Supreme®, in the initial airway management of OHCA compared to current practice, which is expected to be tracheal intubation. The REVIVE team published an initial report in the BMJ on the feasibility of such a study protocol earlier this year. A full trial is expected to follow.

In the meantime, healthcare professionals are still faced with the dilemma of which airway device to use for CPR, so any new data or evidence in this area, even if it is not high level, is likely to be of interest.

Duckett et al have just published the results of two retrospective clinical audits in the Emergency Medicine Journal, reviewing the use of basic and advanced airway management techniques within the UK North East Ambulance Service NHS Foundation Trust (NEAS) for cardiac arrests, entitled, ‘Introduction of the i-gel supraglottic airway device for prehospital airway management in a UK ambulance service.’

The audit confirmed that a range of basic and advanced airway management techniques are being successfully used to manage the airways of CA patients in NEAS and that i-gel is emerging as a popular choice for maintaining and securing the airway during pre-hospital CPR.

The success rates for i-gel insertion at 94% and 92% were higher than for the endotracheal tube (ETT) at 90% and 86%. In determining these results, the Quality Improvement Officer audited whether the technique used had been documented by the crew as ‘successful’ or ‘unsuccessful’, but no further details are provided in this report as to how success or failure was determined. Any additional relevant documentation which may indicate problems such as regurgitation, aspiration or trauma provided by the paramedic and/or the receiving A&E department were also considered. The abstract reports that ‘The re-audit indicated an upward trend in the popularity of i-gel; insertion is faster with a higher success rate, which allows the crew to progress with the other resuscitation measures more promptly.’

In light of this new data, it is interesting to note that an addition to the i-gel product range, specially designed for use during resuscitation, is also now available. The i-gel O2 Resus Pack (figure 1) contains a modified i-gel with a supplementary oxygen port.

figure 1

figure 1

It also includes a sachet of lubricant for quick and easy lubrication of the i-gel O2 prior to insertion, an airway support strap to secure the i-gel O2 in position and a suction tube for insertion through the gastric channel to empty the stomach contents (figure 2)

figure 2

figure 2

The i-gel O2 has been designed to facilitate ventilation as part of standard resuscitation protocols such as those designated by the ERC.

However, the i-gel O2 incorporates a supplementary oxygen port, permitting use for the delivery of passive oxygenation or Passive Airway Management (PAM), as part of an appropriate CardioCerebral Resuscitation (CCR) protocol. The use of passive oxygenation is discussed in an earlier blog post, Should we be passive about oxygenation?

Paediatric Intersurgical i-gel® – is it an advance over other SADs?

8201_i-gel_1_side_on_white
In 2009, Pediatric Anesthesia published a paper by White, Cook and Stoddart, entitled, ‘A critique of elective pediatric supraglottic airway devices’, which aimed to present the evidence surrounding the use of currently available supraglottic airways (SADs) in routine anaesthetic practice. It was one of the first papers to divide SADs in to first and second generation devices. First generation devices were described as simple airway tubes, and second generation devices, such as i-gel®, as incorporating ‘specific design features to improve safety by protecting against regurgitation and aspiration’.

The review highlighted that, apart from the LMA Classic® (cLMA) and LMA Proseal® (pLMA), there was a lack of high quality data of efficacy for SADs, stating that, ‘The best evidence requires a randomized controlled trial comparing a new device against an established alternative, properly powered to detect clinically relevant differences in clinically important outcomes. Such studies in children are rare. Safety data is even harder to establish, particularly for rare events such as aspiration’.

Whilst the authors did comment on the i-gel, at the time of their review paediatric sizes of the device were not available. However, they did note the i-gel offers, ‘the possibility of a genuine improvement on the pLMA’, based on the stability provided in adult sizes by the elliptoid shape of the device, but that it remained to be seen whether this stability would be retained in the paediatric sizes. The review concluded that ‘The pLMA has yet to be outperformed by any other SAD, making it the premier SAD in children and the benchmark by which newer second generation devices should now be compared’.

(fig 1)

(fig 1)

Paediatric sizes of i-gel (fig 1) became available in the latter half of 2009, extending the lower weight range from 30kg to 2kg. As with the adult sizes, the paediatric sizes have a non-inflatable cuff, a gastric channel (except size 1), an integral bite block and a buccal cavity stabiliser. Details of the applicable weight range for each size are shown below (fig 2).

untitled

(fig 2)

The first independent data on the use of the new paediatric sizes came from the Hautepierre University Hospital of Strasbourg, who presented an abstract on the device at the SFAR Congress in Paris in September 2009 and at the Amercian Society of Anesthesiologists (ASA) Annual Meeting in October 2009, entitled, ‘The i-gel in paediatric surgery: Initial series’. This abstract reported on 50 insertions of the device in patients between 6 months and 14 years. Stability of the device and avoidance of intubation were seen as advantages. An interview with Professor Pierre Diemunsch, Consultant at the Hautepierre University Hospital, discussing their findings is available on YouTube.

A number of observational/cohort studies followed. Beringer et al studied the i-gel in 120 anaesthetised patients to assess efficacy and usability. First time insertion success was 92%, overall insertion success was 99% and the median leak (seal) pressure was 20cm H2O. One child regurgitated without aspirating. 16 manipulations were required in 11 children to improve the airway. The authors concluded that, ‘other complications and side effects were infrequent. The i-gel was inserted without complications, establishing a clear airway and enabling spontaneous and controlled ventilation in 113 (94%) children.’

Hughes et al studied the device in 154 children. First time insertion success was 93.5%, overall insertion success was 99.3%. The median leak (seal) pressure was 20cm H2O. The authors concluded that i-gel provided a satisfactory airway during anesthesia for spontaneously breathing infants and children, but felt that to ensure a clear airway, considerable vigilance is required when fixing the device in the mouth.

Fixation is important. The instructions for use for the paediatric i-gel make it clear that as soon as insertion has been successfully completed, the i-gel should be held in place until and whilst the device is secured in place with tape maxilla to maxilla.

Randomised comparative studies followed. The first by Theiler et al, compared i-gel to the Ambu® AuraOnce. This was followed by comparisons to the cLMA . Lee et al found a similar leak pressure between i-gel and the cLMA, but a shorter insertion time for i-gel – 17 secs median (IQR 13.8 – 20.0) v 21.0 secs median (IQR 17.5 – 25.0) and an improved glottic view.

A summary of seal pressures from published clinical studies for the paediatric sizes of i-gel is shown below (fig 3)

Paediatric i-gel seal pressures

(fig 3 ) Paediatric i-gel seal pressures

Considering the conclusion made by White, Cook and Stoddart, perhaps the most interesting comparisons are those to the pLMA.

Two such comparative studies have so far been published. The first was a randomised prospective study entitled, ‘Comparison of size 2 i-gel supraglottic airway with LMA-ProSeal and LMA-Classic in spontaneously breathing children undergoing elective surgery’, which compared the devices in 120 children aged 2-5 years scheduled for surgery of <1 hour duration. The oropharyngeal seal pressure for i-gel was higher than both the cLMA and the pLMA: 26, 22 and 23 cmH20 respectively. First time insertion success was also higher for the i-gel than both the cLMA and the pLMA, 95%, 90% and 90% respectively. The authors concluded that ‘Pediatric size 2 i-gel is easy to insert and provides higher OSP compared with the same size pLMA and cLMA in spontaneously breathing children undergoing elective surgery. It may be a safe alternative to LMA in day care surgeries.

In November 2012, Acta Anaesthesiologica Scandinavica, published a crossover design study by Gasteiger, Brimacombe, Oswald, Perkhofer, Tonin, Keller and Tiefenthaler, entitled ‘LMA ProSeal® vs i-gel in ventilated children: a randomised, crossover study using the size 2 mask‘. The paper studied fifty one children aged 1.5 – 6 years. Leak pressure for both devices was similar, as was fibreoptic position, with the vocal cords visible from the distal airway tube in 94% and 96% respectively. The authors concluded that ‘oropharyngeal leak pressure and fibreoptic position of the airway tube are similar for the size 2 LMA ProSeal® and i-gel in non-paralysed ventilated children’

Clinical evidence takes time to build, and some of the studies looked at one size only and all studies have limitations. However, the above evidence suggests i-gel may yet prove to be ‘a genuine improvement on the pLMA‘, as thought possible by White, Cook and Stoddart back in 2009.

Interestingly, a number of other studies on paediatric i-gel have recently been published, including, ‘A randomised equivalence trial comparing the i-gel and the laryngeal mask airway Supreme in children‘, in which i-gel had a higher seal pressure than the sLMA, 20 (IQR 18-25) v 17 (14-22) cm H20 respectively.

A comparison of three supraglottic airway devices used by healthcare professionals during paediatric resuscitation simulation‘ compared the i-gel to the Laryngeal Tube (LTS) and the LMA Unique® (uLMA) in manikins. A total of 66 healthcare providers, 22 paramedics, 22 nurse anaesthetists and 22 anaesthesia residents participated in the study. The authors concluded that ‘In terms of both the time required for successful placement and the rate of successful placement, the i-gel is superior to the laryngeal mask and tube in paediatric resuscitation simulations by healthcare workers with different levels of experience with paediatric airway management‘.

More data is awaited.

Note:
i-gel is a registered trademark of Intersurgical Ltd. Continue reading

REVIVE airway study

The European Resuscitation Council (ERC) guidelines state that ‘There are no data supporting the routine use of any specific approach to airway management during cardiac arrest. The best technique is dependent on the precise circumstances of the cardiac arrest and the competence of the rescuer.’

In an editorial published in Resuscitation in 2009, entitled, ‘Airway Management for out-of-hospital cardiac arrest – more data required’, Nolan and Lockey confirmed that whilst tracheal intubation has been considered the gold standard for airway management during cardiac arrest, there is no high level evidence proving that tracheal intubation improves outcome. They also highlighted that virtually all data relating to the use of supraglottic airway devices (SADs) in cardiac arrest derive from low level studies, and concluded there is an urgent need for high-quality randomised controlled trials of the use of SADs for cardiopulmonary resuscitation (CPR).

The Airway Management Feasibility Study (REVIVE – Airways) is an attempt to start the process of providing just such evidence, by conducting a randomised comparison of the ventilation success of two 2nd generation supraglottic airways, i-gel® and the LMA Supreme®, in the initial airway management of out-of-hospital cardiac arrest (OHCA) compared to current practice, which is expected to be tracheal intubation. Clinical research in OHCA can be particularly difficult and is often an ethical challenge. Randomisation is not straightforward, so this study is of a cluster randomised design, whereby the randomisation is of the paramedic (as opposed to the patient) to one of the SADs or to ‘current practice’. This is a feasibility study, so the focus is on assessing how easy it is to recruit paramedics, and whether the study design will allow effective comparison of each of the three study arms. Secondary objectives include survival to hospital discharge. If the study does produce useful data, it is hoped this will lead to a national trial.

At the recent International Conference on Emergency Medicine (ICEM) in Dublin, the REVIVE Airway Working Group presented a poster confirming successful recruitment of 184 paramedics employed by Great Western Ambulance Service (GWAS) to the study. This exceeded their target of 150 – a recruitment of 35% of those eligible. The study is expected to end in February 2013. If the methodology proves successful, perhaps there is a chance we might see published data from a national study by 2016. That may seem a long time away, but it should be worth the wait.