The only reason we get away with giving such large doses of epinephrine to these patients is that they are already dead.

- Rogue Medic

Prove it – Ventilation improves survival from cardiac arrest

ResearchBlogging.org

Is a dead person going to be resuscitated sooner if we decrease the return of blood to the heart?

Ventilations decrease the return of blood to the heart.

Is a dead person going to be resuscitated sooner if we decrease whatever blood pressure we are creating with continuous chest compressions?

Ventilations decrease blood pressure, too.

Is a dead person short of breath?

Not unless resuscitated.

Is a person in cardiac arrest from an arrhythmia going to be hypoxic?

Probably not, but that depends on many factors other than ventilation.

How much oxygen is required by dead people to keep vital organs from failing?

The fans of unnecessary ventilations don’t know, but they believe that ventilation is important in cardiac arrest, because it is important agt other times.

 

Image credit.

Ventilations are too important to eliminate because of decreased survival!

Or is it more important to improve survival?

We have been hearing that the new CPR (CardioPulmonary Resuscitation) is not ABCs (Airway, Breathing, and Circulation – a mnemonic that is not more important than understanding what works, but some of us do not understand that). The new mnemonic is CBA (Circulation, Breathing, Airway).

CBA is also wrong.

Two things matter – continuous chest compressions (CCC? – it would be easy to remember, but how hard is this material?) and defibrillation (ZAP?), but not ventilations (NAY, NAY, NAY).

How good is continuous chest compression CPR?

Based on decades of resuscitation research, experts at the University of Arizona Sarver Heart Center developed an EMS protocol termed cardiocerebral resuscitation (CCR).10–22 This protocol emphasizes high quality, minimally interrupted chest compressions, delayed active ventilation, and early epinephrine administration.[1]

While I am not in favor of epinephrine, which is another treatment that is not supported by any evidence of improved survival, it is good to be able to demonstrate that the elimination of some treatments does not harm outcomes, but actually improves survival.

Since this always comes up, I will mention this exclusion early –

Children under 18 years of age, arrests witnessed by the medics, and presumed noncardiac etiologies of the arrest were excluded from the primary analysis.[1]

 

Intubation was delayed until after 3 series of chest compressions – more than 6 minutes after EMS began resuscitation.

The new CCR protocol was presented to EMS directors throughout the state, and they were given the option of instituting CCR in their systems. Over the 3-year period under analysis, approximately 30 of the 62 EMS systems participating in the SHARE Registry elected to implement CCR. CCR training was provided using a train-the-trainer model. Trainers in participating EMS systems were given written materials, slides, and verbal and psychomotor instruction.[1]

This was a retrospective review of resuscitation outcomes from a statewide database that covers 80% of Arizona.

This could select for the systems with the highest quality, or the most knowledgeable medical directors, or the medical directors most up to date on resuscitation research – more up to date than the AHA (American Heart Association).

There is one other aspect that may predispose the outcome toward the no ventilation group.

Time to EMS arrival (min), mean ± SD       5.3 (±2.3)       5.8 (±3.7) [1]

Even though there are more than twice as many patients treated with ventilations, the SD (Standard Deviation) of response times is much wider. The opposite should be true. As more data are accumulated, the SD should narrow. The reason for the wider SD is that there is more variability in the ventilation group. The most likely reason for this is more rural responses, where there will be a higher frequency of much longer response times.

How much difference does a mean difference of half a minute make?

Half a minute doesn’t make this much difference –
 


 

Patients had dramatically better survival without ventilations.

Half a minute doesn’t make this much difference, either –
 

V Fib patients had well over 60% survival without ventilations vs. much less than 20% with ventilations.

No. This does not suggest that we would have better outcomes if we placed pillows over the patients’ airways.

This just demonstrates that hypoxia does not develop quickly in cardiac arrest. We are also probably providing adequate gas exchange with compressions without ventilations, just by moving the chest up and down.

How much difference is there when moving the chest up and down with compressions vs. chest rise with ventilations?

Maybe not a lot – at least during cardiac arrest, but we don’t generally perform chest compressions otherwise.

In the subset of 1,024 patients who received CCR, independent predictors of survival included witnessed arrest (OR = 3.3, 95% CI = 1.8 to 6.1), Vfib/Vtach (OR = 7.0, 95% CI = 3.9 to 12.5), agonal respirations (OR = 4.6, 95% CI = 2.6 to 8.2), EMS response time (for each additional minute, OR = 0.87, 95% CI = 0.76 to 0.99), and age (for each additional 10 years, OR = 0.79, 95% CI = 0.67 to 0.93; Table 5). [1]

Each additional minute of response time did decrease survival by a little. Not an unimportant amount, but a half a minute of response time not detectable compared with the dramatic improvement in survival by eliminating compressions ventilations. (Updated 9/12/2012 @ 12:09 – Eliminating compressions would not be a good idea. Thanks to TexasMedicJMB for the correction.)

The quality of the resuscitation has much more of an influence on survival than the response time.

They might have to triple the number of ambulances in systems that use ventilations, just to produce the same results as systems that withhold ventilations.

We speculate that most patients who have severe neurologic deficits die in the hospital. It is also possible that there is less cerebral ischemia with CCR, as there are fewer overall interruptions, and less positive pressure ventilation.[1]

Why do we require ventilations during CPR?

It isn’t because the ventilations do anything good for the patients.

See also –

Prove it: Ventilation improves survival from cardiac arrest
The Research Review
June 07, 2011
by Kenny Navarro
EMS1.com
Article

Footnotes:

[1] Cardiocerebral resuscitation is associated with improved survival and neurologic outcome from out-of-hospital cardiac arrest in elders.
Mosier J, Itty A, Sanders A, Mohler J, Wendel C, Poulsen J, Shellenberger J, Clark L, Bobrow B.
Acad Emerg Med. 2010 Mar;17(3):269-75.
PMID: 20370759 [PubMed - indexed for MEDLINE]

Free Full Text from Academic Emergency Medicine.

Mosier J, Itty A, Sanders A, Mohler J, Wendel C, Poulsen J, Shellenberger J, Clark L, & Bobrow B (2010). Cardiocerebral resuscitation is associated with improved survival and neurologic outcome from out-of-hospital cardiac arrest in elders. Academic emergency medicine : official journal of the Society for Academic Emergency Medicine, 17 (3), 269-75 PMID: 20370759

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Comments

  1. Not an unimportant amount, but a half a minute of response time not detectable compared with the dramatic improvement in survival by eliminating compressions.

    Lol… Oops? Nice post though, thanks for the information.

    The only argument I have for intubation in a full arrest has been brought up in your posts before: isolating the trachea to prevent aspiration. Aspiration pneumonia on top of the status post-arrest of the pt will make their bad day a very bad day. However, I wonder how much vomiting we’d have if we didn’t bag the pt to begin with? Some cardiac arrest pt’s have vomitus in the airway prior to our arrival, but I’ve seen way more that regurgitate due to us pumping breath after breath into the stomach as a “pre-oxygenation” measure for intubation.
    Quit forcing air into a closed container and we may eliminate a good deal of aspirations. But alas, then we wouldn’t have a reason to intubate :)

    • TexasMedicJMB,

      Not an unimportant amount, but a half a minute of response time not detectable compared with the dramatic improvement in survival by eliminating compressions.

      Lol… Oops? Nice post though, thanks for the information.

      Too much typing not enough attention to what I am typing. Thank you for catching that and pointing it out to me.

      The only argument I have for intubation in a full arrest has been brought up in your posts before: isolating the trachea to prevent aspiration. Aspiration pneumonia on top of the status post-arrest of the pt will make their bad day a very bad day. However, I wonder how much vomiting we’d have if we didn’t bag the pt to begin with? Some cardiac arrest pt’s have vomitus in the airway prior to our arrival, but I’ve seen way more that regurgitate due to us pumping breath after breath into the stomach as a “pre-oxygenation” measure for intubation.
      Quit forcing air into a closed container and we may eliminate a good deal of aspirations. But alas, then we wouldn’t have a reason to intubate :-)

      Ventilation does appear to lead to aspiration. Intubation is not as good at protecting against aspiration as we have been led to believe.

      .

  2. Thank you for posting this. In the previous post about spinal immobilization, I asked about the practical aspects of a study where it was impossible to “blind” anyone to technique vs. placebo. The next day, you post a study that does exactly that.

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