Hi folks
This latest update in Resuscitation journal on tracheal intubation versus supraglottic airways in out of hospital cardiac arrest is intriguing. Most countries’ resuscitation guidelines were updated over 12 months ago with consensus statements from major bodies like ILCOR and AHA. The de-emphasis on tracheal intubation and advice that supraglottic airway devices were equivalent to ETI, were prominent changes. Indeed Wang published research only last year seeming to indicate the exact opposite, that prehospital ETI in cardiac arrest was associated with worse outcomes! read this Resuscitation editorial to find out more !
Whats my take on all the evidence for and against what we should be doing in prehospital cardiac arrest airway management? BVM and basic airway manoeuvres should be bread and butter mainstay. A supraglottic airway is fine to start your resuscitation as well. Its easy and quick to place and protects the airway to a reasonable degree. Ideally the next step should be converting to a cuffed tracheal tube, without interrupting CPR. I think this is the key.
Endotracheal Intubation versus Supraglottic Airway Insertion in Out-
of-Hospital Cardiac Arrest
Wang et al, online Jun 2012, Resuscitation.
Abstract
Objective
To simplify airway management and minimize cardiopulmonary resuscitation (CPR) chest compression interruptions, some emergency medical services (EMS) practitioners utilize supraglottic airway (SGA) devices instead of endotracheal intubation (ETI) as the primary airway adjunct in out-of-hospital cardiac arrest (OHCA). We compared the outcomes of patients receiving ETI with those receiving SGA following OHCA.
Methods
We performed a secondary analysis of data from the multicenter Resuscitation Outcomes Consortium (ROC) PRIMED trial. We studied adult non-traumatic OHCA receiving successful SGA insertion (King Laryngeal Tube, Combitube, and Laryngeal Mask Airway) or successful ETI. The primary outcome was survival to hospital discharge with satisfactory functional status (Modified Rankin Scale ≤3). Secondary outcomes included return of spontaneous circulation (ROSC), 24-hour survival, major airway or pulmonary complications (pulmonary edema, internal thoracic or abdominal injuries, acute lung injury, sepsis, and pneumonia). Using multivariable logistic regression, we studied the association between out-of-hospital airway management method (ETI vs. SGA) and OHCA outcomes, adjusting for confounders.
Results
Of 10,455 adult OHCA, 8,487 (81.2%) received ETI and 1,968 (18.8%) received SGA. Survival to hospital discharge with satisfactory functional status was: ETI 4.7%, SGA 3.9%. Compared with successful SGA, successful ETI was associated with increased survival to hospital discharge (adjusted OR 1.40; 95% CI: 1.04, 1.89), ROSC (adjusted OR 1.78; 95% CI: 1.54, 2.04) and 24-hour survival (adjusted OR 1.74; 95% CI: 1.49, 2.04). ETI was not associated with secondary airway or pulmonary complications (adjusted OR 0.84; 95% CI: 0.61, 1.16).
Conclusions
In this secondary analysis of data from the multicenter ROC PRIMED trial, ETI was associated with improved outcomes over SGA insertion after OHCA.
Prehospital and Retrieval Medicine - THE PHARM dedicated to the memory of Dr John Hinds 
This seems logical when you consider the number of ETT cuffs which are overinflated (the literature is pretty damning against EMS on this point). We inflate until the cuff has maximal volume rather than minimal leak.
I am hypothesizing that our anesthesia friends don’t have the changes in carotid blood flow with their SGA’s as the ones preferred in the OR seem to use much lower cuff volumes and they sit differently in the posterior airway.
A KingLT or Combitube has 2 cuffs meant to isolate the trachea by forming giant blocks north and south of the wind-pipe. Compare this to the Air-Q’s or LMA’s which seem to use the cuff more to pick up the bowl and seat it against the glottic opening.
Perhaps pressure guided inflation of all cuffs needs to become the standard? I know EMS is hampered by a perception that it would be better to hyperinflate and “not lose the tube” than to just let the ETT/SGA make minimal sealing pressures.
Certainly interesting literature, but I think I’m on board with you. For areas where the patient is likely to have the SGA in place <1 hour (number is S.W.A.G.) then it remains a feasible option with conversion to an ETT in the ED where far more hands are present. For areas with longer patient handling times or where there are lots of resources available, ETT initially or SGA with conversion to ETT in the field.
Thoughts?
Minh,
It’s an interesting article but I don’t think it should change anyone’s practice. They counted only successful ETI and SGA in their analysis. I think this needs to be studied from an “intention-to-treat” analysis, because the patients with failed intubations causing hypoxemia, hypercarbia, delayed chest compressions or poor compressions are likely to demonstrate more morbidity and mortality.
Really the question should be, “What does the decision to intubate do to a patient in arrest?” versus protocolized, rapid SGA placement out in the field.
-Erik
Erik, I agree with you. However there was that annoying pig study only last month that cast doubt in my mind about cArotid blood flow and SGA use in cardiac arrest. Now this latest analysis published by Wang et al seems to add further doubt for SGA. but you are right. It is an associAtion not causal as this was not an intention to treat analysis and the ROC PRIMED trial was not designed this way. In this secondary analysis, 71% ETI was successful with no SGA attempt. Only 12.2% SGA attempt, without ETI attempt. 1.2% got SGA and ETI successfully combined, which is what Chris Watford is talking about in one of his services, where BLS team places a SGA and then an ALS team arrives and converts to a ETT during. CPR. It is this group that would be really interesting to know how they did overall. Unfortunately primary analysis of this data , this group was allocated as SGA success. The investigators did a secondary sensitivity analysis where they then calculated the results switching this combined successful SGA/ETI group as ETI success, and they declare they found the same results of improved outcomes with ETI.
Take home message for me right now is, if you are doing the BLS fine and you have enough hands available to perform ETI in the prehospital setting, then doing the ETI is going to probably improve outcome. If not then SGA is fine.
We were just starting to discuss the “annoying pig article” on the Society for Airway Management Web Forum. Is this to evolve into another episode of “Fact or Crap?”??
I brought up the following issues:
Thank you for discussing this article. I have a few concerns about this article: My principal question is…Is this article relevant?
1. The size of SGA’s used in 32 kg pigs are appropriate for 70-90 kg humans. Were these SGA’s grossly oversized for these animals? Did they select the SGA size simply based on the length of the airway tubing alone (i.e., so the SGA’s would be long enough to seat and seal in the pharynx?).
LMA size 4, LT size 4, Combitube 41 fr.
2. The oro-pharyngeal anatomy of a pig. I understand that if the SGA is advanced deeply enough, that it will seal in the animal’s pharynx, however, I don’t know what the relationship of the neck vessels are to the SGA position in the pharynx. In the human animal, the carotid arteries are lateral to the hypo pharynx, running like conduits behind the palatoglossal arches. An ENT colleague of mine once punctured a carotid during a routine tonsillectomy, so it’s important to know the course of these vessels from clavicle to base of skull.
3. Were the Combitube and Laryngeal tube and LMA effectively overinflated to achieve a seal pressure?
Lastly, let me say something positive about this article. It questions the use of the current SGA’s that require manual inflation. The newest generation SGA’s that do not require manual inflation may rise above the last generation, namely, the iGel and the Air-Q SP. We actually may need to engage a veterinary anesthesiologist to answer these questions. Adrian, there is one over at the Univ of Wisconsin in Madison that I have spoken with in the past–contact me and I’ll give you the contact information. Last time I spoke with her, she was anesthetizing a porcupine. Do you know how she anesthetized this porcupine? —> Very Carefully.
excellent debate points, Jim! check out Dr A Neill blog article on this anatomical arguement against the study. http://emergencymedicineireland.com/2012/05/22/anatomy-for-emergency-medicine-16-the-lma-as-a-murder-weapon/
Your point about the device sizing is very relevant. Yes another fact or crap episode might be on the cards here…