ILCOR, 2015 and the countdown to new guidelines

8704-000_i-gel_resus_mainAs 2014 draws to a close, it seems a good opportunity to look forward to 2015 and consider what the new year may bring. It does look set to be an interesting year. The inaugural European Games will be held in Baku in June, the 7th Rugby World Cup will take place in England in September and Resuscitation 2015 – The Guidelines Congress, will be held in Prague in October!

Sport can be unpredictable, but the winners of the 2015 Rugby World Cup will almost certainly come from one of just five or six nations. I doubt the new 2015 ERC Resuscitation guidelines will provide us with too many surprises either, and neither should they. The ILCOR Scientific Evidence Evaluation and Review System (SEERS) and Consensus on Resuscitation Science and Treatment Recommendations (CoSTR), from which new guidelines are eventually developed, is a process that should ensure the right questions are asked, the relevant evidence is gathered and reviewed and a consensus on the science is obtained before any treatment recommendations are made. New guidelines then follow.

The ILCOR web-site provides the opportunity to review the current status of the PICO questions. In the Advanced Life Support (ALS) section, two questions in particular caught my attention:

Advanced airway placement (ETT v SGA)

Among adults who are in cardiac arrest in any setting  (P), does tracheal tube insertion as first advanced airway  (I), compared with insertion of a supraglottic airway as first advanced airway  (C), change ROSC, CPR parameters, development of aspiration pneumonia, Survival with Favourable neurological/functional outcome at discharge, 30 days, 60 days, 180 days AND/OR 1 year, Survival only at discharge, 30 days, 60 days, 180 days AND/OR 1 year (O)?

Airway placement (Basic vs Advanced)

Among adults who are in cardiac arrest in any setting (P), does insertion of an advanced airway (ETT or supraglottic airway) (I), compared with basic airway (bag mask +/- oropharyngeal airway) (C), change Survival with Favourable neurological/functional outcome at discharge, 30 days, 60 days, 180 days AND/OR 1 year, Survival only at discharge, 30 days, 60 days, 180 days AND/OR 1 year, ROSC, CPR parameters, development of aspiration pneumonia (O)?

Both of the above subjects have been discussed in previous blog posts. The subject of ETT v SGA was covered in a post from October 2012 entitled, ‘Supraglottic airways versus tracheal intubation for OHCA’ and the latter in a post from February 2013 entitled, ‘Pre-hospital airway management for patients with OHCA’.

Since these blog posts were written, additional evidence has been published and it will be interesting to see what conclusions there are from the SEERS/CoSTR process.

In the Basic Life Support (BLS) section, one question stood out as of particular interest:

 Passive ventilation techniques

Among adults and children who are in cardiac arrest in any setting (P), does addition of any passive ventilation technique (eg positioning the body, opening the airway, passive oxygen administration) to chest compression-only CPR (I), compared with just chest compression-only CPR (C), change Survival with Favourable neurological/functional outcome at discharge, 30 days, 60 days, 180 days AND/OR 1 year, Survival only at discharge, 30 days, 60 days, 180 days AND/OR 1 year, ROSC, bystander initiated CPR, oxygenation (O)?

The subject of passive oxygenation has been covered in two blog posts on this site. The first, published in April 2012, asked the question, ‘Should we be passive about oxygenation?’ and the second, in October 2013, entitled, ‘Passive oxygenation – the jury is still out’, concluded that,

‘…whilst there appears to be very little new published data, passive oxygenation remains a subject of lively debate in resuscitation circles and is often mentioned in articles reviewing ventilation strategies and airway management in cardiac arrest. Before it slips from view due to a lack of new evidence, it is hoped a new wave of studies are already in progress and will soon emerge as peer reviewed published studies in the near future, enabling a more conclusive assessment to be made as to whether passive oxygenation has a useful role to play during CPR. Without doubt, at the present time, the jury remains out.’

I will be interested to see the conclusions  from the SEERS/CoSTR process on this very interesting subject.

There are many other questions of interest in the ALS and BLS sections, as well as in the Neonatal, Paediatric and Education sections, including use of Impedance Threshold Devices, Induced Hypothermia and Exhaled CO2 detection and esophageal detection devices.

As a big sports fan, I am looking forward to both the European Games and the Rugby World Cup, as well as the Cricket World Cup. However, even these major upcoming sporting events are not anticipated with quite the same excitement as Resuscitation 2015 – The Guidelines Conference! I just can’t wait!

Passive oxygenation – the jury is still out

As discussed in my blog post from April 2012, ‘Should we be passive about oxygenation?’, in the years preceding the issue of the 2010 European Resuscitation Council (ERC) and Amercian Heart Association (AHA) guidelines on resuscitation, interest in the concept of passive oxygenation, particularly as a component of CardioCerebral Resuscitation (CCR) protocols, appeared to peak. This led to considerable speculation as to how the International Liaison Committee on Resuscitation (ILCOR) would assess the published evidence regarding passive oxygenation compared to standard ventilation techniques and what the subsequent recommendations would be in the new 2010 ERC and AHA guidelines.

In the end, the ERC concluded that, ‘There is insufficient evidence to support or refute the use of passive oxygen delivery during CPR to improve outcome when compared with oxygen delivery by positive pressure ventilation’, and the AHA that, ‘This time there is insufficient evidence to support the removal of ventilations from CPR performed by ACLS providers.’

It might reasonably have been expected that such conclusions would stimulate potential investigators to intensify their efforts to provide the additional evidence needed to enable more conclusive statements in the next set of guidelines, scheduled for issue in 2015. Disappointingly, this has not been the case, so the jury is still out, with little immediate prospect of having significant new evidence to consider.

There may be any number of reasons for this. One possibility is the debate regarding airway management and ventilation in CPR has simply moved on to other areas of interest, such as the optimal airway device. However, if so, it has progressed without really resolving the question of whether passive oxygenation has a useful role to play during CPR, particularly for the first few minutes following witnessed ventricular fibrillation/ventricular tachycardia (VF/VT).

A key question regarding the concept and viability of passive oxygenation as an alternative to standard ventilation during the initial phase of CPR has always been whether chest compressions generate adequate ventilation in cardiac arrest (providing there is a patent airway).

In the 2010 AHA guidelines for CPR (Part 8), in the section on passive oxygenation delivery during CPR, it is stated that:

‘Chest compressions cause air to be expelled from the chest and oxygen to be drawn into the chest passively due to the elastic recoil of the chest. In theory, because ventilation requirements are lower than normal during cardiac arrest, oxygen supplied by passive delivery is likely to be sufficient for several minutes after onset of cardiac arrest with a patent upper airway.’

In their article, ‘Airway techniques and ventilation strategies’, Nolan and Soar, comment that:

‘A study of 17 intubated patients in an emergency department who were undergoing chest compressions using a mechanical compression device (Lund University Cardiopulmonary Assist System (LUCAS)) showed that the median tidal volume per compression was just 42ml – considerably less than the dead space. These patients had been in cardiac arrest for more than 40 min, and therefore, their lung compliance was probably poor. Nevertheless, the implication is that chest compressions alone do not generate adequate ventilation. Despite this, and based partly on further animal data, a group from the Sarver Heart Center in Tucson, Arizona, the United States, has described the use of passive oxygenation insufflation as part of their protocol for CardioCerebral Resuscitation (CCR). This group has recently reported better survival to hospital discharge after witnessed VF cardiac arrest from adults who were managed initially with passive oxygenation (insertion of an oropharyngeal airway and oxygen given at 15L/min by non-rebreather mask) compared with those given active ventilation.’

Perhaps improvements in survival rates, such as those described above, have been due to factors other than passive oxygenation? Most of the studies on passive oxygenation have included multiple treatment changes and/or a number of confounders, so this remains a possibility.

Despite the lack of significant new data, passive oxygenation has continued to be a subject of discussion in a number of recent articles.

In a review article published in ‘Current Opinion in Critical Care’ (COCC), entitled, ‘Advanced life support and mechanical ventilation’, Kill, Dersch and Wulf discuss, amongst other topics, passive oxygenation versus active ventilation. They conclude that:

‘The total number of studies dealing with mechanical ventilation during resuscitation and ALS is still limited. The still recommended standard is positive-pressure ventilation with a tidal volume of 6-7ml/kg and a respiratory rate of 10/min, purse oxygen and preferably with a ventilator. During the first few minutes of CPR, passive oxygen insufflation via a nonrebreathable mask or an airway device might be an acceptable alternative. Hyper-oxygenation should be avoided once a spontaneous circulation is restored, and waveform capnometry is an important monitoring for both ventilation and perfusion of the lungs.’

In another review published in COCC in 2013, entitled, ‘Airway Management in cardiopulmonary resuscitation’, Soar and Nolan confirm that:

‘Some EMS system protocols for adult primary cardiac arrest include airway opening and high-flow face-mask oxygen, and passive oxygenation from chest compressions for the first 6 minutes of CPR. Improved outcomes have been reported with this ‘minimally interrupted’ CPR approach although further study is needed’. A retrospective analysis of adult OHCA patients reported improved neurologically intact survival after witnessed VF/VT OHCA with passive ventilation compared with bag-valve mask ventilation. Survival was similar for unwitnessed VF/VT and nonshockable rhythms. Observational data from large registries in Japan, however, suggest that ventilation is necessary during CPR in children, after cardiac arrest with a primary respiratory cause, and during a prolonged cardiac arrest.’

As well as delivery using a non-rebreather mask and oropharyngeal airway, passive oxygenation, or passive airway management™ (PAM), can be delivered via a supraglottic airway, such as the Intersurgical i-gel O2™, which incorporates a supplementary oxygen port specifically designed for this purpose (figure 1). Such a device may offer advantages over use of a non-rebreather mask, such as providing the opportunity to switch more seamlessly from passive oxygenation to standard ventilation, thereby minimising interruption to chest compressions. However, this is speculation only and has yet to be confirmed by any published evidence.

Connecting a standard oxygen tube to the supplementary port of the i-gel O2 in preparation for the delivery of passive oxygenation

Connecting a standard oxygen tube to the supplementary port of the i-gel O2 in preparation for the delivery of passive oxygenation

In conclusion, whilst there appears to be very little new published data, passive oxygenation remains a subject of lively debate in resuscitation circles and is often mentioned in articles reviewing ventilation strategies and airway management in cardiac arrest. Before it slips from view due to a lack of new evidence, it is hoped a new wave of studies are already in progress and will soon emerge as peer reviewed published studies in the near future, enabling a more conclusive assessment to be made as to whether passive oxygenation has a useful role to play during CPR. Without doubt, at the present time, the jury remains out.

I would be most interested to hear from anyone who is currently using a protocol which incorporates passive oxygenation, is involved in a study incorporating this technique or is looking to conduct such a study in the future.