And another prehospital airway study (on cardiac arrest)

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medicsb

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Resuscitation. 2014 Feb 18. pii: S0300-9572(14)00093-8.

Airway management and out-of-hospital cardiac arrest outcome in the CARES registry.
McMullan J1, Gerecht R2, Bonomo J2, Robb R3, McNally B3, Donnelly J4, Wang HE4; On behalf of the CARES Surveillance Group.

Abstract
BACKGROUND:

Optimal out of hospital cardiac arrest (OHCA) airway management strategies remain unclear. We compared OHCA outcomes between patients receiving endotracheal intubation (ETI) versus supraglottic airway (SGA), and between patients receiving [ETI or SGA] and those receiving no advanced airway.
METHODS:

We studied adult OHCA in the Cardiac Arrest Registry to Enhance Survival (CARES). Primary exposures were ETI, SGA, or no advanced prehospital airway placed. Primary outcomes were sustained ROSC, survival to hospital admission, survival to hospital discharge, and neurologically-intact survival to hospital discharge (cerebral performance category 1-2). Propensity scores characterized the probability of receiving ETI, SGA, or no advanced airway. We adjusted for Utstein confounders. Multivariable random effects regression accounted for clustering by EMS agency. We compared outcomes between 1) ETI vs. SGA, and 2) [no advanced airway] vs. [ETI or SGA].
RESULTS:

Of 10,691 OHCA, 5,591 received ETI, 3,110 SGA, and 1,929 had no advanced airway. Unadjusted neurologically-intact survival was: ETI 5.4%, SGA 5.2%, no advanced airway 18.6%. Compared with SGA, ETI achieved higher sustained ROSC (OR 1.35; 95%CI 1.19-1.54), survival to hospital admission (1.36; 1.19-1.55), hospital survival (1.41; 1.14-1.76) and hospital discharge with good neurologic outcome (1.44; 1.10-1.88). Compared with [ETI or SGA], patients receiving no advanced airway attained higher survival to hospital admission (1.31; 1.16-1.49), hospital survival (2.96; 2.50-3.51) and hospital discharge with good neurologic outcome (4.24; 3.46-5.20).
CONCLUSION:

In CARES, survival was higher among OHCA receiving ETI than those receiving SGA, and for patients who received no advanced airway than those receiving ETI or SGA.


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My hypothesis for the results:

1. "No airway" has better outcomes as patient who are most likely to survive will end up in this group (e.g. the patient that gets ROSC prior to any airway attempt, or, even prior to ALS arrival). (The no airway group had 8.7% getting shocked with an AED by a bystander vs. the 5.8 in the ETI group, but it was 9.8% for SGA, so that is confounding. Also the no airway group had 18.6% witnessed by EMS vs 10% for ETI. No airway was also more likely to be in a public location or within a health institution.)

2. SGA has worse outcomes because those that could not be intubated end up in this group (my assumption: they had the greatest duration of interruptions of chest compressions). And then there is the possibility that some of these device may impede cerebral blood flow, so there is that.

Anyhow, these are based on a rather cursory reading of the article, so I'm curious if anyone else has any opinions.

I don't think this is a good basis to say "no airway" is really better, but it is good support for a RCT.
 
Read it all. Nice study.

They attempted EVERYTHING they could to remove confounding variables during the statistical analysis. They were suprised by their results even after these mitigating calculations. The discussion section attempts to explain away the difference between no airway and ETI.

Although our findings of an association of improved outcomes with no advanced airway management are consistent with previous reports, we urge caution in the interpretation of those and the current findings. Confounding by indication is of major influence in studies of medical interventions.11 Unlike the comparison of ETI vs. SGA, the observed survival differences between the airway and non-airway groups were very large, even after stratification by initial ECG rhythm, propensity score adjustment and propensity score matching. We believe that the large associations – despite the use of multivariable adjustment and propensity score matching – reflect the presence of unmeasured and immeasurable confounders. For example, the non-airway group may have included patients who regained airway reflexes, spontaneous respirations, or consciousness during EMS treatment. Patients with these findings would be expected to have superior outcomes compared with comatose individuals. We note that patients who did not receive an advanced airway were more likely to be found in a shockable cardiac rhythm, have their OHCA witnessed by EMS, or receive therapy from an AED. Other unmeasured confounders such as short distance to the hospital, provider procedural skill, perceived health status of the patient, and airway anatomic factors may have also influenced the decision to not insert an advanced airway. Additional study must integrate detailed information regarding the course of airway management such as the number and duration of attempts, rates of ventilation, and airway interventions carried out in the receiving ED.
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Similar explanation for SGA is suggested, that it may be a d/t being a rescue airway to the extreme impact that the data failing to be corrected by their analysis.

So basically, the data do not reflect expectations after attempted controls. Either the results are novel (ie ETI and SGA are not beneficial) or are nonrepresentative needing to explain away the data.
 
The patients who do not get airways may be less sick?
And how much time was being lost to various airway attempts before reception at definitive care?



Same as the study which showed that people not receiving IV in the field did better than those who did.

Illustrative sidebar: a local hospital made the news with their notably higher infant mortality rate than pother local hospitals. Someone called the station and told them the hospital received all the most critical infant cases from the others.

Acuity times length of trip to definitive care=mortality.

Time without adequate cerebral and cardiac perfusion divided by time enroute with adequate perfusion=mortality.

Make sure your attempts at interventions don't prolong time to definitive care unless they can greatly decrease, or remove, time without adequate cardio-cerebral perfusion, and then even if they will help they cannot exceed the time before organoic death...or even arrival at the hospital!
 
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medicsb said:
My hypothesis for the results:

1. "No airway" has better outcomes as patient who are most likely to survive will end up in this group (e.g. the patient that gets ROSC prior to any airway attempt, or, even prior to ALS arrival). (The no airway group had 8.7% getting shocked with an AED by a bystander vs. the 5.8 in the ETI group, but it was 9.8% for SGA, so that is confounding. Also the no airway group had 18.6% witnessed by EMS vs 10% for ETI. No airway was also more likely to be in a public location or within a health institution.)

2. SGA has worse outcomes because those that could not be intubated end up in this group (my assumption: they had the greatest duration of interruptions of chest compressions). And then there is the possibility that some of these device may impede cerebral blood flow, so there is that.

Anyhow, these are based on a rather cursory reading of the article, so I'm curious if anyone else has any opinions.

I don't think this is a good basis to say "no airway" is really better, but it is good support for a RCT.
Click to expand...

Yep, interesting stuff here. I have not read it closely either, but based on what I've seen of it I completely agree with what you are putting forward here.

What I've always said about prehospital airway management in general is that there are so many confounders that truly definitive studies will likely never be done, at least until training and practices become much more homogenous across the US. There are just too many variables from place to place. Different initial training, different continuing training, different protocols, different provider experience levels, different drugs, different types of airways, different patient populations, different transport times, different patient presentations that are difficult to account for in a study; i.e. subtle clinical differences can seriously impact the airway management plan, etc.
 
Apparently the Resuscitation Outcomes Consortium is planning to do a RCT of SGA vs. ETI if they can continue to get funding.

https://roc.uwctc.org/tiki/tiki-download_file.php?fileId=15674

“ROC AIRWAY” Primary Endotracheal Intuation vs. Supraglottic Airway (SGA) insertion.

"The objective of this study is to compare the outcomes of adult OHCAs treated with primary ETI versus those treated with primary SGA insertion.
Specific Aim I: Determine how EMS advanced airway management strategy affects outcomes (survival to hospital discharge with MRS≤3, 24‐hour survival, return of spontaneous circulation) after adult OHCA."

"The study will involve two treatment categories:

- Primary (ETI) Airway Management. In this “traditional” arm, basic life support
personnel (BLS) will use bag‐valve‐mask (BVM) ventilation only, while advanced life support (ALS) personnel will use ETI as the primary advanced airway technique. ALS rescuers may revert to BVM or SGA in the event of failed ETI efforts.

- Primary SGA Airway Management. This “experimental” part of the study will be executed in two different ways. In systems where BLS agencies do not use SGA, BLS personnel will use BVM ventilation only, and ALS personnel will attempt SGA insertion as the primary airway strategy. In systems where BLS agencies use SGA (select agencies in British Columbia and Ottawa), both BLS and ALS personnel will attempt SGA insertion as the primary"

"Treatment randomization
The trial will use cluster randomization at the EMS agency level; ROC EMS agencies and personnel are already accustomed to this approach. Patient‐level randomization requires the preparation of blinded airway equipment pouches, which is neither feasible nor practical given the range of airway equipment used by EMS."

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I hope that the study will be modified to add a BVM arm, but it'd still be a good study as planned.
 
Sounds like it could generate data from which other inferences could be made as well. Good deal.
 
Interesting. Has there been anything recent on SGA use causing decreased cerebral blood flow which may cause the worse outcome?
 
That really will be a cool study. All my cardiac arrests get a SGA and IO. I got more important stuff to do than worry about than an ET tube and IO's are as effective as central lines. (download the EasyIO app and they have a fluroscope video of contrast fluid going through a humeral IO. It changed my perspective on them entirely.) The procedures together probably take 2 min from prepeartion to confirmation.
 
Smash said:
What's the rush?
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picture.php

Single combat with death.​
 
How many times have we all been on a scene where someone is hell-bent on getting an advanced airway, to the effect that everything else is compromised. I believe that a basic airway is more beneficial than someone stopping compressions to attempt their 3rd intubation, only to be able to put a proverbial notch in their statistical bedpost. Definitive care is not 15 minutes on scene preparing the patient for the ER.

Interesting read though, evidence that prehospital medicine is every-changing.
 
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I read this as further confirmation that uninterrupted compressions are the key to SCA survival. As others have stated, the attempts to place a ET interfere with compressions, and ultimately good ventilation doesnt matter if the blood isnt going round and round

But it is promising to see research being done
 
MedicSlayer said:
How many times have we all been on a scene where someone is hell-bent on getting an advanced airway, to the effect that everything else is compromised. I believe that a basic airway is more beneficial than someone stopping compressions to attempt their 3rd intubation, only to be able to put a proverbial notch in their statistical bedpost. Definitive care is not 15 minutes on scene preparing the patient for the ER.

Interesting read though, evidence that prehospital medicine is every-changing.
Click to expand...

Hopefully we have put a stop to this were I work, for the most part. With the use of a LUCAS device we have seen increases in "saves" and there is no need to stop compressions to get an airway.
 
If your attempts to intubate are hindering quality compressions, you shouldn't be intubating. If your attempts are not doing so, I am not so sure there is a deleterious effect on outcomes. I don't think that this study necessarily shows that ETT is bad, as others have mentioned.
 
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