2018 ACLS Review – Help From EMC’s Episode 71 ACLS Guidelines 2015 – Cardiac Arrest Controversies Part 1

Next week I’ll be recertifying in Basic Life Support and in Advanced Cardiac Life Support. In addition to reviewing all the course materials before the courses, I like to review additional resources.

Today I reviewed Episodes 71 and 72 from Emergency Medicine Cases. I listened to both podcasts and reviewed both sets of show notes.

I’ve chosen not to excerpt anything from Episode 72 but it is still worth careful review.

In this post I’ve made some excerpts of the show notes of Episode 71:

Cardiopulmonary Resuscitation emphasizing high quality, minimally‐interrupted chest compressions to maximize blood flow to the brain, an important theoretical determinant of long term survival.

Circulation-Airway-Breathing as opposed to the classic Airway-Breathing-Circulation is how we should approach these patients because of the realization that arterial oxygen saturation remains high for the first 5‐10min of a cardiac arrest, that recoil of the chest during chest compressions improves oxygenation, that delaying a definitive airway increases survival, and that high quality continuous compressions improves survival.

In Toronto, the survival rate overall for cardiac arrest has improved from 2% in 2004 to 13% in 2015, probably related to improved early defibrillation and improved quality of chest compressions. The survival rate for Ventricular Fibrillation in Toronto has risen from 8% in 2004 to 35% in 2015.

Caveat: because children usually die as a result of asphyxia and respiratory complications, early ventilations should be emphasized in the pediatric population.

The key to successful life-saving CPR is to minimize the intervals during which cardiac compression is stopped.

In order to minimize compression pauses for pulse checks, our experts recommend two approaches:

1. Have a dedicated experienced provider feeling for a manual femoral pulse during chest compressions so that as soon as a pause in chest compressions to assess for cardiac rhythm occurs at the end of 2 minutes of compressions, the pulse can be rapidly assessed along with the cardiac rhythm in less than 5 seconds (as apposed to less than 10 seconds as recommended in the guidelines).

2. Do not check for the pulse at all! Chest compressions should continue until your end tidal CO2 monitor shows persistent elevations. The argument here is that palpating for a pulse has been shown to be insensitive, not specific and have poor inter-rater reliability. One study showed that rescuer pulse palpation was only 78% accurate. Even if a pulse is felt, this does not guarantee adequate perfusion to vital organs. Dr. Morrison suggests stopping chest compressions only to assess for defibrillation and to defibrillate. An alternative to manual pulse checks suggested by Dr. Weingart in Part 2 of this series is to establish an early arterial line so that the moment a pause in chest compressions occurs, providers know if there is an increase in arterial pressure.

emcases-update Update 2015: Trial in NEJM compares continuous vs interrupted chest compressions (30:2) and finds that as long as the chest compression fraction is >75% then there appears to be no difference in survival to hospital discharge. Abstract. Analysis on The Bottom Line.

Simulation training plays an important role in optimizing performance of cardiac arrest teams. Like NASCAR tire replacement teams, the cardiac arrest team should be proficient at performing their specific dedicated tasks. Observational data from the Resucitation Outcomes Consortium (ROC) show that the larger the cardiac arrest team the better the outcome. Where as previous guidelines focused on developing the skills of the leader of the resuscitation, current trends are to develop skills of each individual on the cardiac arrest team.

Optimizing Epinephrine in Cardiac Arrest

Multiple factors may contribute to the effectiveness of epinephrine in cardiac arrest:

  1. Timing
  2. Dose and frequency of administration
  3. Underlying rhythm and suspected diagnosis

Timing

The Guidelines recommend administering epinephrine as early as possible in the resuscitation.

Observational data suggests that the first dose of epinephrine is administered at 22 minutes on average after cardiac arrest. Some experts believe that earlier administration in the first 4 minutes during the ‘circulatory phase’ of cardiac arrest may improve long term outcomes, but there is only observational data for this in the literature.

One observational study of cardiac arrest with non-shockable rhythm compared epinephrine given at 1 to 3 minutes with epinephrine given at 3 later time intervals (4 to 6, 7 to 9, and greater than 9 minutes). The study found an association between early administration of epinephrine and increased ROSC, survival to hospital discharge, and neurologically intact survival.

Dose and Frequency of Administration

Some experts believe that the dose of 1mg every 3-5 minutes that is recommended in the guidelines is too high a dose, is too frequently given and may be detrimental. Epinephrine, in the doses used in cardiac arrest, causes cerebral vasoconstriction that may impair tissue oxygenation, brain perfusion and compromise neurological recovery.

Scott Weingart describes titrating epinephrine in cardiac arrest to hemodynamic parameters and end tidal CO2 in this EMCrit podcast, and in Part 2 of this podcast. Titrating to diastolic BP, as described in the Paradis study in JAMA requires early placement of an arterial line during ongoing chest compressions. While end tidal CO2 is an excellent marker for chest compression quality and determining ROSC, titrating epinephrine to end tidal CO2 goals have never been shown to be associated with long term outcomes.

A physiologic measure of brain oxygenation measured by near-infrared spectroscopy may be a better marker to titrate epinephrine to in cardiac arrest, but currently there is no evidence in the literature to support its use.

Underlying rhythm and suspected diagnosis

In most patients in ventricular fibrillation the primary cause is an MI. Some experts believe that we should lower the dose of epinephrine in patients with ventricular fibrillation as a the primary rhythm during cardiac arrest to minimize the vasoconstriction of the coronary arteries caused by epinephrine given at 1mg every 3-5 minutes.

In patients with non-shockable rhythms (PEA, asystole), early administration of epinephrine may be more beneficial than in patients’ whose presenting rhythm is ventricular fibrillation.

Additional Resources

(1) HIGHLIGHTS of the 2015 American Heart Association Guidelines Update for CPR and ECC [Full Text PDF]

(2) 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2015;132:S313–S314, originally published November 3, 2015

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