Is plastic in the trachea during cardiac arrest harmful?

I have being reflecting lately on intubation of critically ill patients.  There are few other topics in prehospital care which raise strong opinions, often from polar perspectives.  There are numerous papers on the safety and effectiveness of advanced airway management in multiple populations (http://wp.me/P2N7pf-2K) often with conflicting results.

Unfortunately, training in airway skills is very heterogeneous – with the majority of paramedics learning all airway skills in simulated settings and utilising these skills infrequently on real patients.  All paramedics are expected to be proficient at bag mask ventilation, insertion of oropharyngeal airways (OPA), nasopharyngeal airways and supraglottic airways (SGA) however most have learnt these skills on manikins; will have infrequently used these skills in practice and typically use/attempt these skills without a more senior mentor being present.  It is therefore difficult for paramedics to acquire / maintain “basic” airway skills of which the use of an OPA and ability to mask ventilate are the most important.  Additionally, there is evidence that paramedics success rates for insertions of laryngeal mask airways is well below what is expected (i.e. > 90%).  The majority of intensive care paramedics (ICPs) in Australia have undertaken some perioperative airway training however this is of variable duration (typically between 1-4 weeks) with some jurisdictions requiring a minimum of 20 intubations.  ICPs are aware after this period of training that the perioperative area is very different to the prehospital environment when it comes to endotracheal intubation.  Furthermore, the opportunity for the majority of paramedics to perform endotrachael intubation are infrequent.

I want to take the opportunity to explore why placing a plastic tube in the trachea during cardiac arrest might adversely affect outcomes and propose ways that these factors might be overcome

Possible mechanism Solution
Intubation can impair the delivery of effective and minimally interrupted chest compressions
  • Attempts at intubation must not interfere with chest compressions (the person doing compressions should not stop)
  • Attempt all intubations with a bougie – it is easier to intubate the glottis with a bougie than an ETT especially during CPR
  • Skill train paramedics to intubate with a bougie without interrupting chest compressions
  • Only attempt intubation if glottis view is IIb or better – chances of first pass success with grade III and IV views without interrupting chest compressions are unlikely
  • Monitor CPR performance
  • Attempts at intubation might be delayed until ROSC or gasping respiration ceases – great article by Gordon Ewy –http://www.sjtrem.com/content/pdf/1757-7241-20-65.pdf
Intubation can lead to hyperventilation of patients
  • Have paramedics train and practice delivering one breath every 6 seconds
  • Use a portable ventilator
  • Use objective measures of ventilation rate (i.e. waveform capnography)
  • Monitor CPR performance
Paramedics only intubate infrequently
  • It is true that the majority of paramedics intubate infrequently reflecting the incidence of cardiac arrest
  • Paramedics (and their employers) should ensure regular refresher training and ongoing opportunities to maintain airway skills (also important for ED and ICU docs)
  • Use an airway registry to document prehospital intubation attempts prospectively
Oesophageal intubation will not be recognised
Paramedics will become fixated on needing to definitively secure the airway
  • Change the culture that being able to ventilate the patient is the only absolute requirement in cardiac arrest
  • Change the culture that being able to intubate is the most important measure of a paramedics greatness
  • Ensure that an “unsuccessful” intubation drill is in place, practiced and is utilised
  • Introduce intubating LMAs and/or second generation LMAs

 

All “intubators” (whether medical or paramedical) have a responsibility to not harm their patients.  Whilst proceduralists like performing procedures, there is a patient at the end of every procedure.  It is highly unlikely that the endotracheal tube reacts with the mucosa of the trachea in such a way that outcomes are worse – there must be other reasons.  In my mind, all of which readily come to mind can be overcome quite readily.

Bottom line

  • Intubation must not impair effective and continuous (or minimally interrupted) chest compressions
  • Attempts at intubation must be brief, consider delaying until after ROSC
  • Do not hyperventilate – use a ventilator if available (if unavailable lobby the bureaucracy)
  • Optimise first pass success – optimise positioning, use external laryngeal manipulation, use suction and use a bougie
  • Waveform capnography should be used routinely (if unavailable lobby the bureaucracy)
  • If any difficulty – move on (don’t let your ego get the better of you – display clinical leadership by implementing plan B which facilitates oxygenation / ventilation
Advertisements

2 thoughts on “Is plastic in the trachea during cardiac arrest harmful?

  1. Marty Nichols

    Hello Jason,

    What a great post. I concur with everything you have said. Clinical decision making skills and judgement appear to be the key to the future of paramedic ETI.

    I particularly enjoyed your statement ‘it is highly unlikely that the endotracheal tube reacts with the mucosa of the trachea in such a way that outcomes are worse – there must be other reasons’.

    For better or worse it will be the clinical decision making skills and abilities of ICP’s that determine whether or not pre-hospital cardiac arrest ETI receives its ‘final nail in the coffin’ or not. A technician is able to intubate, but a clinician knows when it will be beneficial.

    Marty

    Reply
  2. Francsois

    Hi Dr Bendall

    Great article, I agree with everything you said. I too suspect that it is not intubation, but hyperventilation, interruption to chest compressions and CPR, and delays to defibrillation that are the likely culprits. To be sure, a controlled trial comparing ETI to basic intervention is needed. I do not believe it would be ethical to test ETI in a trial AS ETI HAS BEEN PRACTICED UP TO NOW, that is with likely CPR interruptions, hyperventilation etc., since it is quit obvious that interrupting CPR and hyperventilation is likely to be very harmful. How should we test ETI in a trial then? By testing whether intubating a patient after the return of spontaneous circulation (ROSC) increases survival, compared to not intubating at all. However, there is a problem with only tubing persons in a trial that experience ROSC. Enrolments for such a trial would be very low, as perhaps 25% of persons in cardiac arrest experience ROSC. This is bad news, as it makes such a trial less-than-likely, since a trial where everyone in cardiac arrest (not just ROSC) is already a mammoth undertaking. It has been suggested that to show a 1% difference in survival, we would need to enrol 10000 patients! How long would it take to enrol such a number if we only limit intubation to persons with ROSC? As I said earlier, I believe intubating persons with ROSC, and not interrupting compressions is the way to go. Other alternatives are delaying intubation as they have been doing in some staes in the USA, or trying to intubate with compression going on, which is quite difficult.

    Cheers

    Francsois Fouche

    Reply

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s