It is important for EMS providers to not only be up to date on
cardiac arrest standards, but also to understand the studies
underpinning them
Ever since the first care report of
successful modern CPR was published in 1960, research aimed at refining
it has grown exponentially.1 Early AHA guidelines for ACLS, in 1974, were quite different than current ones, although many core components have persisted.2, 3
Even across recent years, standards of care have changed dramatically;
it wasn’t long ago that capnography was relatively unknown to EMS and
placing the tube was priority number one. At present, the AHA guidelines
are updated every five years, most recently in 2010. Guideline changes
are based on a literature review performed by experts in various fields
across the world, a process that has already begun for the 2015 update.
The International Liaison Committee on Resuscitation (ILCOR) is the
coordinating body that sifts through reviewers’ recommendations and
proposes changes. As the frontline providers in cardiac arrest care, it
is important for EMS providers to not only be up to date on cardiac
arrest standards, but also to understand the studies underpinning them.
This article reviews recent literature that may soon change the way you
care for your most ill patients.
Medication Use in Cardiac Arrest
It has been more than 10 years since bretylium, isoproterenol and
high-dose epinephrine were questioned for their usefulness in cardiac
arrest, and removed from both the guidelines and ambulances.4 More recently, in 2005, lidocaine was largely replaced by amiodarone.5 Only two years ago, with the 2010 changes, was atropine removed.6
Today, standard epinephrine, vasopressin and even the antiarrhythmics
are being questioned in large research trials. A recent editorial in the
Journal of the American Medical Association (JAMA) claimed,
“The best available observational evidence indicates that epinephrine
may be harmful to patients during cardiac arrest, and there are
plausible biological reasons to support this.”7
Epinephrine, long considered a core component of cardiac arrest
management, has never been properly studied for effectiveness. In fact,
neither have most of the cardiac arrest medications until recently. It
was only in 2003 that a group of researchers in Norway decided to
evaluate medication effectiveness in a six-year randomized trial in
which patients received either a normal regimen of IV drugs by
paramedics or none. The results were surprising: although return of
spontaneous circulation (ROSC) rates were improved (32% in the control
group receiving normal medications vs. 21% in the trial group receiving
placebo), there was no change in all other outcomes. These other
outcomes included survival to discharge, favorable neurological outcome
and one-year survival.8 These results raised an important
question that healthcare providers are obligated to consider: What is
considered good outcome? Is more ROSC really a good thing when survival
to discharge and neurological outcome are unchanged? Put in a
population-based context, this question becomes: Is this the best use of
healthcare resources?
In 2006, a group in Western Australia performed a randomized trial
that put epinephrine against placebo. Similar to the Norway study,
paramedics gave either real epinephrine or placebo to cardiac arrest
patients without knowing which was which—a “blinded” study. This study
again showed a higher ROSC in the epinephrine group (23.5%) than the
placebo group (8.4%). However, this study also showed there was no
statistically significant change in survival to discharge, prompting the
same questions as the previous study.9 Difficulties with the
execution of this study highlighted some important issues for EMS
providers to consider as our field becomes increasingly research-driven
and evidence-based. Although planned as a multicenter study to include a
larger number of patients, four out of five EMS services refused to
participate as they felt it unethical to “withhold the standard of
care,” meaning epinephrine. As EMS providers we need to decide what is
truly unethical: that, or relying on an unproven medication, which may
not help or may even harm patients, simply because “that’s how it’s
always been done.” The lack of agency participation and negative press
led to this study being halted early. As the authors of this study put
it, barriers to research such as this “serve only to ensure such
interventions remain unproven.”
In March 2012, a Japanese research group
looked prospectively at ED admissions for cardiac arrest that received
either epinephrine or nothing during initial treatment, which was based
on the type of responder on scene. In looking at over 400,000 patients
they found similar results: ROSC was improved (18% vs. 5% here) but
one-month survival was unchanged, and, most interestingly, neurological
outcomes were worse. Although the difference was small—1.4% in the
epinephrine group had good functional status at one month as opposed to
2.2% in the placebo group—this was a very statistically significant
change in such a large study and should force us to question the
treatment we call the standard of care.10
The authors of the Japanese Hagihara study propose some theories for
their findings based on previous animal-based research of epinephrine.
They report it has been shown to increase lactate and over-constrict the
microcirculation throughout the body, which could lead to an overall
net increase in metabolic debt created during the arrest that is
unrecoverable post-arrest. Further, epinephrine has been shown to
promote post-arrest arrhythmias and to activate platelets, both of which
may worsen outcomes.
Although the epinephrine debate is still some time from being
settled, a large-scale multicenter trial in North America is about to
begin that will help settle another medication controversy. The
“Amiodarone, Lidocaine or Neither (Placebo) for Out-Of-Hospital Cardiac
Arrest Due to Ventricular Fibrillation or Tachycardia (ALPS)” study,
headed out of the University of Washington, will compare amiodarone,
lidocaine and placebo use by EMS in cardiac arrest. The results of this
study, and possible future epinephrine studies, will help the
resuscitation community determine the best treatment for our patients. A
final bit about vasopressin, which is still considered to be an
adequate alternative to epinephrine in cardiac arrest: A 2012
meta-analysis of six randomized controlled trials that compared
epinephrine against vasopressin found no improvement in sustained ROSC,
long-term survival or favorable neurological outcome. It did, however,
find a slightly higher long-term survival in asystole patients.11
Intubation & Supraglottic Airways
Airway control methods in the field for cardiac arrest and other
unstable patients have been a heavily debated topic for some time. It
was a study out of Los Angeles published in 2000 that surprised many
when it clearly demonstrated outcomes for pediatric cardiac arrest
patients intubated in the field were no better, and possibly worse, than
those who were managed with a BVM.12 While now accepted as a
reasonable alternative to not intubate pediatric cardiac arrests in the
field in lieu of BVM ventilation per current PALS guidelines, it
remains unclear what is best for adults. The 2010 ACLS guidelines state,
“If advanced airway placement will interrupt chest compressions,
providers may consider deferring insertion of the airway until the
patient fails to respond to initial CPR and defibrillation attempts, or
demonstrates ROSC,” and since their publication new studies have
continued to suggest intubation may not be the most optimal treatment in
the field.13
Supraglottic airways (SGA), such as King tubes, laryngeal mask
airways (LMA), Combitubes and others, have emerged as useful
alternatives to endotracheal intubation (ETI) over the past few years. A
Japanese study of witnessed non-traumatic out-of-hospital cardiac
arrests (OHCA) included over 5,000 patients and showed favorable
neurologic outcome was the same (3.6%) regardless of whether an
endotracheal tube or SGA was used. A longer time to placement was noted
for ETI, though, which could lead to longer scene times for these
patients.14
The National EMS Information System (NEMSIS) data has been adding to
our understanding of airway management outcomes in the United States. A
look at NEMSIS data from 16 states and 4.3 million EMS calls in 2008
showed a dramatic 10% improvement (87% vs. 77%) in successful airway
management when an SGA was used as opposed to ETI. “Successful airway
management” was defined as the ability to ventilate, and SGAs included
the Combitube, LMA, esophageal obturator airway (EOA) and King LT.15
Besides strongly supporting SGAs as the preferred method, this paper
raised important questions regarding the ability of EMS providers to
intubate in the field (a 77% success rate was shown in just over 10,000
intubation attempts). This was in contrast to a meta-analysis published a
year earlier that reported an 86.3% success rate in field intubation;
the reason for this disparity is unclear.16
Smaller retrospective studies continue to
be published regarding field intubation in cardiac arrest, and they are
nearly universally supportive of abandoning the practice. Data from
three states published in 2010—Michigan, California and North
Carolina—showed poorer outcomes for intubated patients in cardiac
arrest. In Michigan, VF/VT survival to discharge was decreased with
field intubation.17 In California, survival to discharge was
over four times greater for patients treated with BVM ventilation as
opposed to intubation.18 Finally, in North Carolina ROSC was over five times more likely in nonintubated patients.19
While none of these studies are conclusive, taken together they should
force the EMS community to consider the use of alternative airways if
they aren’t already doing so.
Vascular Access
With the advent of rapid intraosseous (IO) access thanks to various
drill-based devices, the best method for obtaining primary vascular
access in cardiac arrest must be questioned. A randomized trial in North
Carolina had paramedics start a tibial IO, a humeral IO or a peripheral
IV (PIV) as first-line access in cardiac arrest patients to evaluate
this. The results speak for themselves: access was obtained on the first
attempt in 91% of tibial IO patients as opposed to 51% for humeral IO
and 43% for PIV. The time taken for initial success was quickest with a
tibial IO as well.20 The AHA clearly supports the use of
these devices in adults, and it is reasonable for EMS agencies to
consider using them for first-line access in cardiac arrest.
CPR Devices & Pumps
Various adjuncts to CPR have been developed and used in an attempt to
optimize or enhance the manual delivery of compressions and
ventilations. Two of the more common mechanical compression devices are
the load-distributing band CRP model (the ZOLL AutoPulse) and the
mechanical piston model (Physio-Control LUCAS). Despite a natural
inclination to believe these devices would improve CPR, field research
trials have to date been unsupportive.
The AutoPulse was studied in a multicenter randomized trial in 2004,
during which EMS providers either used the AutoPulse or performed
regular CPR. The study was halted early due to safety concerns after an
interim review of results showed survival to discharge in the AutoPulse
groups to be over 40% lower than the regular CPR group. Survival at four
hours, however, was similar.21 A number of reasons were
suggested for this finding, including a learning curve for the device,
delayed time to device deployment, a Hawthorne effect (control group
doing more effective CPR than normal since they were being monitored)
and enrollment bias (using the AutoPulse on people who normally would
have been pronounced in the field).
The Lund University Cardiac Arrest System (LUCAS) device has not yet
been properly studied in a randomized fashion; however, such a study is
scheduled to begin in the United States soon and a European one is
ongoing. A pilot study in Sweden showed the device led to no improvement
in early survival though, so the AHA has yet to endorse the routine use
of this product.22 Given the risks of performing CPR in a
moving ambulance and the necessary gaps in compressions during patient
movement, an automated compression device seems like good fit for EMS.
The current and upcoming LUCAS trials will help answer the important
question of if our patients truly benefit from it.
Impedance threshold devices (ITD) were the subject of a multicenter
randomized controlled trial in the U.S. and Canada that was halted early
in 2009 for futility. The ITD had been shown to improve hemodynamics
and survival in animal studies, and this trial attempted to reproduce
that effect in human patients. By blocking passive inflow of air into
the chest during CPR compression recoil, the device increases negative
intrathoracic pressure and therefore increases venous return leading to a
higher cardiac output. Patients in the study were assigned to receive
care with either an actual ITD or a sham ITD, and paramedics were
blinded to which they were using. After an interim evaluation of over
8,000 patients showed no difference in survival between the two study
groups, it was decided further enrollment would not change the outcome.23
Although this study demonstrated no benefit to using the ITD, one
area of ongoing discussion is the use of it in conjunction with active
compression-decompression CPR. One study showed a survival benefit when
used together and as such that remains a reasonable approach to care.24
he AHA recognized in 2010 that the field of
CPR adjuncts was rapidly evolving; however, they were unable to provide
a positive recommendation for their use at the time. The authors of the
guidelines made the following statement immediately following their
non-recommendation: “The experts are aware of several clinical trials of
the devices listed below that are underway and/or recently concluded,
so readers are encouraged to monitor for the publication of additional
trial results in peer-reviewed journals and AHA scientific advisory
statements.”25
STEMI Centers & Cardiac Arrest Centers
Regionalizing care in the U.S. through the creation of specialty
centers has been effective for many years at reducing the mortality of
trauma patients, burn patients and pediatric patients. Stroke centers
were a more recent innovation and while initially shown to be effective,
they now are coming under scrutiny. Recent research shows the stroke
center hospitals were better in providing stroke care even before the
stroke center designation, and even after implementation gains in
survival and neurologic recovery are modest.26,27
STEMI and cardiac arrest centers are the newest iteration of this
movement and it appears the survival gains may be modest here as well. A
recently published study compared the outcomes of STEMI patients
between hospitals in North Carolina participating in a regionalization
model with those that weren’t, and also with national trends. It showed
that, although mortality has improved, the improvement in STEMI centers
was no better than in the preexisting system.28 As the
authors of this study noted, this raises important questions for system
administrators as they develop their own regionalized STEMI center
systems. Further, this brings into question the proposed model of
cardiac arrest centers emerging in many cities, as it is largely based
on the stroke and STEMI models.
Defibrillation Timing & Dosing
Since the 2005 AHA guideline revision, an extra step was included in
the defibrillation decision making tree. If a patient was found in
cardiac arrest by EMS, and no bystander CPR was being performed, then
the provider was to perform two minutes of CPR prior to defibrillation.
However, if bystander CPR was in progress, the provider should
immediately proceed to defibrillation. If the arrest was witnessed by
EMS, defibrillation should be done immediately as well. This was based
on the hypothesis that CPR prior to defibrillation could improve
myocardial perfusion, thereby improving the likelihood of a successful
defibrillation.29
Whether this theory leads to better outcomes was evaluated in a
multicenter trial in North America by the Resuscitation Outcomes
Consortium (ROC) investigators from 2007 to 2009. They found there was
no difference in outcomes of cardiac arrest patients for whom 30–60
seconds of CPR (enough time to place pads and prepare the defibrillator)
or 180 seconds of CPR was performed. Additionally, their data suggested
a possible decrease in survival for patients in ventricular tachycardia
or ventricular fibrillation who received 180 seconds of CPR.30
Resuscitation Research
The International Liaison Committee on Resuscitation (ILCOR) promotes
and coordinates resuscitation research and guideline development
worldwide. It is made up of representative organizations from the United
States (American Heart Association), Europe (European Resuscitation
Council), Canada (Heart and Stroke Foundation of Canada), and other
nations and regions, such as the Australian and New Zealand Committee on
Resuscitation, Resuscitation Councils of Southern Africa, Inter
American Heart Foundation and Resuscitation Council of Asia. During
their meetings, research is reviewed and guidelines are developed
through consensus. It is from these meetings that the AHA guidelines
here in the U.S. largely arise. Learn more at
www.ilcor.org.
Conclusion
Cardiac arrest management is the bread and butter of the EMS skill
set. Of all the fields and specialties in healthcare, EMTs and
paramedics stand out as the experts, capable of managing these critical
patients in suboptimal settings often with inadequate personnel. The
foundation of this knowledge and skill set is built in the original EMT
and paramedic courses and refined throughout years of BCLS, ACLS and
PALS refresher courses. As this review demonstrates, the hypotheses and
science behind these guidelines are critically evaluated in a constant
fashion. As healthcare providers on the front lines we must stay up to
date on the research and understand the findings in order to provide the
best possible care to our patients.
References
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3. Goldberg AH. Cardiopulmonary arrest. NEJM, 1974 Feb; 290(7): 381–5.
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8. Olasveengen TM, Sunde K, Brunborg C, et al. Intravenous drug
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12. Gausche M, Lewis RJ, Stratton SJ, et al. Effect of
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14. Kajino K, Iwami T, Kitamura T, et al. Comparison of supraglottic
airway versus endotracheal intubation for the prehospital treatment of
out-of-hospital cardiac arrest. Crit Care, 2011; 15(5): R236.
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16. Hubble MW, Brown L, Wilfong DA, et al. A meta-analysis of
prehospital airway control techniques, part I: orotracheal and
nasotracheal intubation success rates. Prehosp Emerg Care, 2010; 14: 377–401.
17. Egly J, Custodio D, Bishop N, et al. Assessing the impact of
prehospital intubation on survival in out-of-hospital cardiac arrest. Prehosp Emerg Care, 2011 Jan–Mar; 15(1): 44–9.
18. Hanif MA, Kaji AH, Niemann JT, et al. Advanced airway management
does not improve outcome of out-of-hospital cardiac arrest. Acad Emerg Med, 2010 Sep; 17(9): 926–31.
19. Studnek JR, Thestrup L, Vandeventer S, et al. The association
between prehospital endotracheal intubation attempts and survival to
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20. Reades R, Studnek JR, Vandeventer S, et al. Intraosseous versus
intravenous vascular access during out-of-hospital cardiac arrest: a
randomized controlled trial. Ann Emerg Med, 2011 Dec; 58(6): 509–16.
21. Hallstrom A, Rea TD, Sayre MR, et al. Manual chest compression
vs. use of an automated chest compression device during resuscitation
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22. Smekal D, Johansson J, Huzevka T, et al. A pilot study of
mechanical chest compressions with the LUCAS device in cardiopulmonary
resuscitation. Resuscitation, 2011 Jun; 82(6): 702–6.
23. Aufderheide TP, Nichol G, Rea TD, et al. A trial of an impedance threshold device in out-of-hospital cardiac arrest. NEJM, 2011 Sep; 365(9): 798–806.
24. Aufderheide TP, Frascone RJ, Wayne MA,
et al. Standard cardiopulmonary resuscitation versus active
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cardiac arrest: a randomized trial. Lancet, 2011; 377: 301–311.
25. Cave DM, Gazmuri RJ, Otto, CW, et al. 2010 AHA guidelines for CPR and ECC science, part 7: CPR techniques and devices. Resuscitation, 2010; 122: S720–S728.
26. Lichtman JH, Allen NB, Wang Y, et al. Stroke patient outcomes on
U.S. hospitals before the start of the Joint Commission Primary Stroke
Center certification program. Stroke, 2009 Nov; 40(11): 3574–9.
27. Litchman JH, Jones SB, Wang Y, et al. Outcomes after ischemic
stroke for hospitals with and without Joint Commission-certified primary
stroke centers. Neurology, 2011 Jun 7; 76(23): 1976–82.
28. Glickman SW, Greiner MA, Lin L, et al. Assessment of temporal
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29. AHA. 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation, 2005; 112: IV1–203.
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Sean M. Kivlehan, MD, MPH, NREMT-P, is an emergency medicine
resident at the University of California San Francisco and a former New
York City paramedic for 10 years. Contact him at sean.kivlehan@gmail.com.
posted
by Dr. Ramon Reyes, MD ∞
𓃗 #DrRamonReyesMD ∞ 𓃗 @DrRamonReyesMD
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Gracias a todos el Canal somos mas de 1000 participantes en WhatsApp. Recordar este es un canal y sirve de enlace para entrar a los tres grupos; TACMED, TRAUMA y Científico. ahí es que se puede interactuar y publicar. Si le molestan las notificaciones, solo tiene que silenciarlas y así se beneficia de la informacion y la puede revisar cuando usted así lo disponga sin el molestoso sonido de dichas actualizaciones, Gracias a todos Dr. Ramon Reyes, MD Enlace al
