Cut the Breathing, Save Lives

In a follow-up to January’s analysis of COCPR, Rick Bukata, MD, reviews a new round of
abstracts and answers the question: Is compression-only CPR data too good to be true?

In a follow-up to January’s analysis of COCPR, Rick Bukata, MD, reviews a new round of
abstracts and answers the question: Is compression-only CPR data too good to be true?

Changing what is recommended in the way of layperson-performed CPR performance is a big deal. The last thing you want to do is confuse people or appear unsure given that so many have been trained in traditional CPR. But now we see a growing number of papers that suggest that CPR without rescue breathing is equivalent to CPR with it – or even superior to it. So what is the answer? Let’s look at the most recent study on this topic.

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The study that I find most impressive is by Bentley Bobrow and 13 colleagues. It looked at the results of prehospital cardiac arrests after the initiation of a statewide program in Arizona, which began in 2005 to encourage use of compression-only CPR by laymen.

Their campaign was multifaceted and nothing short of extraordinary. It included brief, on-line video training, free, in-person training in a large variety of settings, public service announcements made by the governor and local sports celebrities, inserts in utility bills, education at health and safety fairs, newspaper articles and editorials, a training video looped on public access channels, summer youth classes, local radio spots and interviews, special features on local and national TV and frequent e-mail updates to stakeholders.

In March of 2008, the AHA came out with an Advisory Statement supporting compression-only CPR which was widely publicized as an additional aspect of the ongoing educational program. In a state of 6.6 million residents they estimated that at least 30,000 people were directly trained in compression-only CPR and another 500,000 were exposed to at least one compression-only media forum.

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A five-year prospective, observational cohort study of survival in patients at least 18 years old with out-of-hospital cardiac arrest occurring between January 1, 2005 and December 31, 2009 was conducted looking at the relationship between layperson CPR and survival to hospital discharge. Their results were nothing short of remarkable.

A total of 4,415 arrests not observed by emergency personnel met all inclusion criteria – 2900 received no bystander CPR, 666 received conventional CPR and 849 received compression-only CPR. Rates of survival to hospital discharge were 5.2%, 7.8% and 13.3%. Almost too good to be true! Over the duration of the study lay rescuer CPR increased from 28% to 40% and, most impressively, the proportion that was compression-only CPR increased from 20% to 76%.

The authors note that their study is one of at least eight indicating that compression-only CPR is at least as good as conventional CPR. The more fundamental question now is do we advise that all prehospital CPR by laymen be compression-only and traditional CPR be abandoned. Given the impressive results of this study and the fact that the other studies demonstrate compression-only CPR to be at least as good as standard CPR it appears that it may be time to consider this action. Given the significance of the magnitude of this change in procedure, it sure would be great if there were at least one confirming study.

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My approach to situations like this is to weigh benefits and risks given limited information. Considering that the outcome of CPR and prehospital ALS is a very big deal (survival and neurologic outcome), and that compression-only CPR is highly likely to be as good as standard CPR, what should we do? Since there is the potential that compression-only CPR may be significantly superior, it seems prudent to convert all CPR instruction to compression-only CPR at this time and encourage the transition to compression-only CPR for those previously taught standard CPR.

Not only will this potentially substantially improve outcomes (if the Arizona data holds) but it will obviously decrease the natural and substantial reluctance to perform CPR given that mouth-to-mouth breathing will not be “required” or encouraged as part of the procedure. Unfortunately, it will not be easy to duplicate the Arizona study and even if it is duplicated it will take years to know the results. In the meantime we want patients to be availed of the most effective therapy that we know and currently it is compression-only CPR.

The authors of this study, and the architects of the statewide educational campaign, are to be commended. Their accomplishments are remarkable and the fruits of their labors should make all of the participants in this endeavor very, very proud of what they have accomplished.

CHEST COMPRESSION-ONLY CPR BY LAY RESCUERS AND SURVIVAL FROM OUT-OF-HOSPITAL CARDIAC ARREST
Bobrow, B.J., et al, JAMA 304(13):1447, October 6, 2010

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METHODS: This prospective observational study, from the Arizona Department of Health Services, examined the effects of a public campaign promoting compression-only CPR on performance of CPR by lay bystanders and survival in adults experiencing a prehospital cardiac arrest of presumed cardiac etiology, unwitnessed by EMS personnel, from 2005 through 2009.

RESULTS: Of 4,415 arrests, the provision of CPR by lay bystanders increased from 28.2% in 2005 to 39.9% in 2009, with compression-only CPR accounting for 19.6% of bystander CPR in 2005 but 75.9% in 2009. Overall survival to hospital discharge increased from 3.7% in 2005 to 9.8% in 2009. Survival rates were 5.2% in patients receiving no bystander CPR, 7.8% in those receiving conventional CPR, and 13.3% in patients receiving compression-only CPR by lay bystanders (corresponding rates of survival with good neurologic status were 3.0%, 5.2% and 7.6%, respectively). In the subgroup with cardiac arrests witnessed by a lay bystander in the setting of a shockable rhythm on EMS arrival, rates of survival to discharge were just over 17% in patients receiving no CPR or conventional CPR, but 33.7% in those receiving compression-only CPR. On multivariate logistic regression analysis that controlled for potential confounders, bystander provision of compression-only CPR was associated with an increased likelihood of survival when compared with no provision of bystander CPR (odds ratio [OR] 1.59) or conventional bystander CPR (OR 1.60).

CONCLUSIONS: A public campaign endorsing compression-only CPR was associated with increased provision of bystander CPR to adults with prehospital cardiac arrests and improved survival. 37 references (bobrowb@azdhs.gov – no reprints) (20924010 [PMID]) March, 2011, Copyright 2011 by Emergency Medical Abstracts — All Rights Reserved

There appears to be one major caveat regarding the use of compression-only CPR. It should not be used in children. Certainly, children are in the minority of prehospital arrests. In the Bobrow study, above, although excluded from the study because of age criteria, of the 5,272 arrests initially considered for the study, 297 were pediatric cases (5.6%) and in the subset in which rescue breathing would have provided the most benefit (children aged less that 12) the proportion who received compression-only CPR was only 10 of 127. Given that most pediatric arrests are anoxic, it would seem that ventilation would remain an important component of CPR in this subset. Here is a paper that makes this specific point.

Arrests in children 17 and younger occurring in Japan between 2005 through 2007 were studied. Of the huge number of cases (5,170) only 29% were believed due to a cardiac etiology. Almost half had bystander CPR. In the subgroup thought to have an arrest due to cardiac causes, the one-month survival with good neurologic outcomes was similar with both standard and compression-only CPR (9.9% vs 8.9%), however, there was a marked difference in outcomes in the subset felt to have a non-cardiac
origin for their arrest (7.2% with standard CPR vs 1.6% for compression-only CPR). It’s clear that children should have standard CPR due to the fact that, in most, the etiology is non-cardiac and results were not substantially different between those with cardiac arrests when standard CPR was compared with compression-only CPR.

CONVENTIONAL AND CHEST-COMPRESSION-ONLY CARDIOPULMONARY RESUSCITATION BY BYSTANDERS FOR CHILDREN WHO HAVE OUT-OF-HOSPITAL CARDIAC ARRESTS: A PROSPECTIVE, NATIONWIDE, POPULATION-BASED COHORT STUDY
Kitamura, T., et al, Lancet 375:1347, April 17, 2010

BACKGROUND: In children, unlike adults, cardiac arrest is often precipitated by a non-cardiac (respiratory) cause, and it is not certain if compression-only CPR is comparable to conventional CPR (with rescue breathing) in this circumstance.

METHODS: These Japanese authors examined prospective registry data for prehospital cardiac arrest in children aged 17 or younger occurring in 2005 through 2007 to evaluate outcomes achieved after bystander-initiated conventional or compression-only CPR.

RESULTS: Among 5,170 arrests, only 29% were believed to be due to a cardiac etiology. Bystander CPR was provided in 47% of cases. On logistic regression analysis, provision of any bystander CPR was associated with better one-month survival with favorable neurologic status (the primary study outcome, 4.5% vs. 1.9% with no bystander CPR). In the subgroup of children with an arrest of presumed cardiac origin, favorable neurologic outcome at one month was relatively frequent following both conventional and compression-only bystander CPR (9.9% vs. 8.9%), but in the larger group with arrest of a non-cardiac origin, this favorable outcome was much more common with conventional than with compression-only CPR (7.2% vs. 1.6%, respectively). Of note, a favorable outcome was much less likely in infants aged one year or younger than in older children.

CONCLUSIONS: Any provision of bystander CPR is associated with improved outcome in children with prehospital cardiac arrest. Conventional CPR, however, appears to be much more effective than compression-only CPR in those children whose arrest is of non-cardiac origin, who comprise almost three-quarters of all such cases. 36 references (iwamit@e-mail.jp – no reprints) August, 2010 Copyright 2010 by Emergency Medical Abstracts – All Rights Reserved

One last point. Faster, Harder, Deeper – performed to the rhythm of “Stayin’ Alive” by the Bee Gees – that’s the new mantra for performing chest compressions. This next paper makes it clear that you have to put some muscle into your chest compressing and reaffirms that chest compression should be stopped for the shortest time possible (if it is going to be stopped at all) before shocking.  One of the problems associated with watching simulated CPR on any TV shows is that it, by necessity, is not performed with any gusto at all. Laymen who watch and emulate this pseudo-CPR are not doing the patient a favor.

Somehow, it would be great if they could put on the screen when pseudo-CPR is being performed that this is really not the way to do it – but, obviously, that won’t happen.

EFFECTS OF COMPRESSION DEPTH AND PRE-SHOCK PAUSES PREDICT DEFIBRILLATION FAILURE DURING CARDIAC ARREST
Edelson, D.P., et al, Resuscitation 71:137, 2006

BACKGROUND: Some studies have reported that cardiopulmonary resuscitation (CPR) prior to shock administration might influence the success of defibrillation in patients with ventricular fibrillation (VF).

METHODS: This observational study, from the University of Chicago and University Hospital in Oslo, Norway, and supported by Laerdal Medical Corp., evaluated the effect of the depth of chest compression during CPR and the duration of the pause in CPR prior to attempted defibrillation on outcomes in 60 cardiac arrest patients receiving a first shock for VF (55% prehospital arrests). Chest compression depth was determined using an investigational monitor- defibrillator.

RESULTS: Overall, VF was terminated with a first shock in 73% of the patients; return of spontaneous circulation was achieved in 53% but only 7% (four patients) survived to hospital discharge. There was a relationship between a successful shock and the median duration of the pre-shock pause (11.9 vs. 22.7 seconds) and between success and the median depth of chest compression prior to the pre-shock pause (39mm vs. 29mm). The odds ratios (ORs) for a successful shock were 1.86 for every 5-second decrease in the duration of the pre-shock pause (p=0.021), and 1.99 for every 5mm increase in the depth of chest compression (p=0.028). The likelihood of a successful shock was not influenced by the CPR ventilation or compression rates.

CONCLUSIONS: In patients with VF, the likelihood of a successful defibrillatory shock appears to be influenced by the depth of chest compression during CPR and the duration of the pre- shock pause. The authors cite the availability of newer automatic external defibrillators (AEDs) with shorter analysis times. 35 references (babella@medicine.bsd.uchicago.edu) April, 2007 Copyright 2007 by Emergency Medical Abstracts – All Rights Reserved

So it appears that what we should do in the setting of prehospital arrests is pretty clear with regard to what laymen should do – aggressive continuous chest compression without ventilation – except for children, in which ventilation is still advised. What about when the paramedics arrive. What should they do? Bobrow and associates performed another study in which high-flow oxygen was passively given in conjunction with an oropharyngeal airway and a facemask and compared this with standard bag-valve-mask ventilation. They note in this study that “… the latest protocols defer advanced airway interventions such as endotracheal intubation, substituting basic-level airway measures” in order to give preference to continuous chest compressions without interruption (although specific references supporting this assertion are not cited, see below for some studies that are in agreement). The minimally interrupted protocol more specifically included four phases – 200 uninterrupted preshock chest compressions followed by 200 uninterrupted post-shock chest compressions before pulse check or rhythm analysis. Intubation was only attempted after three cycles of 200 chest compressions and rhythm analysis. Before or during the second cycle of chest compressions, an attempt was made to give IV or intraosseous epinephrine.  

The study looked retrospectively at 1,019 adult prehospital arrests with 459 receiving the passive ventilation and 560 receiving the bag-valve-mask ventilation. In the witness, ventricular fibrillation or tachycardia subset adjusted neurologically intact survival was higher for the passive ventilation (39/102 (38%) vs bag-valve-mask ventilation (31/120 (26%). Survival was statistically similar in the subset with unwitnessed ventricular fibrillation / tachycardia arrests and those with nonshockable rhythms (although trends clearly favored bag-valve-mask ventilation in this subset.  

Here are a couple of compelling papers indicating that outcomes with attempted intubation are inferior to those with bag-valve-mask ventilation – a very surprising turn of events given the emphasis on intubation in the past.

THE ASSOCIATION BETWEEN PREHOSPITAL ENDOTRACHEAL INTUBATION ATTEMPTS AND SURVIVAL TO HOSPITAL DISCHARGE AMONG OUT-OF-HOSPITAL CARDIAC ARREST PATIENTS
Studnek, J.R., et al, Acad Emerg Med 17(9):918, September 2010

BACKGROUND: Recommendations for the management of prehospital cardiac arrest by the American Heart Association now emphasize minimal interruption of chest compressions with a reduced focus on advanced airway management.

METHODS: This study, from Carolinas Medical Center, retrospectively analyzed the relationship between outcomes and prehospital endotrach
eal intubation (ETI) attempts in 1,142 adults with out-of-hospital nontraumatic cardiac arrests managed by paramedics.

RESULTS: A single successful prehospital attempt at ETI was documented for 50.5% of the patients, a single unsuccessful attempt for 6.1%, multiple attempts with successful ETI for 11.6%, multiple attempts without success for 14.0%, and no attempted ETI for 17.8%. Rates of sustained prehospital return of spontaneous circulation (ROSC) were highest for patients in whom ETI was not attempted (45.3% vs. 25.3% with a single successful attempt, 28.6% with a single unsuccessful attempt, and 17.4% and 11.3% for multiple successful or unsuccessful attempts, respectively). A similar pattern was observed for survival to hospital discharge (28.6% when ETI was not attempted vs. 3-16% in the other groups). After controlling for potential confounders, odds ratios (ORs) in the group without attempted ETI (compared with those having one successful attempt) were 2.33 for sustained ROSC and 5.46 for survival to hospital discharge.

CONCLUSIONS: The authors acknowledge the limitations of their study design, but note that their findings suggest a negative association between attempted ETI in patients with prehospital cardiac arrests and ROSC / survival to discharge. 42 references (jonst@medic911.com for reprints) Copyright 2011 by Emergency Medical Abstracts – All Rights Reserved 2/11 – #3

ADVANCED AIRWAY MANAGEMENT DOES NOT IMPROVE OUTCOME OF OUT-OF-HOSPITAL CARDIAC ARREST
Hanif, M.A., et al, Acad Emerg Med 17(9):926, September 2010

BACKGROUND: Although some authors have endorsed endotracheal intubation as the criterion standard for prehospital airway management, recent literature suggests that intubation has no survival advantage over bag-valve-mask (BVM) ventilation in this population, and may in fact lead to worse outcomes. Studies of non-traumatic prehospital arrest have also reported improved survival with BMV ventilation compared to intubation, and when chest compression and defibrillation (rather than intubation) are the primary focus.

METHODS: This study, from Harbor-UCLA Medical Center in Torrance, CA, reviewed charts of 1,294 adults with prehospital non-traumatic cardiac arrest to compare rates of survival to hospital discharge among those managed in the field with endotracheal intubation or with BVM ventilation.

RESULTS: Most of the patients underwent intubation in the field (79.4%), while only 10.1% were managed with BVM ventilation, and the remaining patients were managed with another intervention (e.g., esophageal obturator, Combitube). Rates of survival to hospital discharge were 4% in patients managed with prehospital intubation vs. 11% among those managed with BVM ventilation. After controlling for potential confounders, including age, gender, site of arrest, initial arrest rhythm, whether or not the arrest was witnessed, and provision of bystander CPR, the odds ratio [OR] for survival to hospital discharge with BVM ventilation rather than endotracheal intubation was 4.5 (95% CI 2.3-8.9).

CONCLUSIONS: In this chart review study, field management of adults sustaining prehospital non-traumatic cardiac arrest with BVM ventilation rather than endotracheal intubation was associated with a greater than four-fold increase in survival to hospital discharge. 40 references (jniemann@emedharbor.edu for reprints) Copyright 2011 by Emergency Medical Abstracts – All Rights Reserved 1/11 – #5

The Arizona protocol, as described, no longer provides shocks upon arrival of the paramedics in those with shockable rhythms. They have performed studies that have suggested that a period of chest compression prior to shock is superior to immediate shocking. This is somewhat controversial in that not all studies have agreed with this approach.  The following study claims that, based on a systematic review and meta-analysis, there is no compelling evidence that the strategy of performing a series of chest compressions prior to defibrillation is beneficial (nor harmful).

DELAYED VERSUS IMMEDIATE DEFIBRILLATION FOR OUT-OF-HOSPITAL CARDIAC ARREST DUE TO VENTRICULAR FIBRILLATION: A SYSTEMATIC REVIEW AND META-ANALYSIS OF RANDOMISED CONTROLLED TRIALS
Simpson, P.M., et al, Resuscitation 81(8):925, August 2010

BACKGROUND: Based on the results of animal studies, prediction models and two human studies, in 2005 the International Liaison Committee on Resuscitation (ILCOR) recommended delaying defibrillation to allow a short period of CPR in patients with unwitnessed prehospital cardiac arrest due to ventricular fibrillation (VF).

METHODS: These Australian authors performed a systematic review and meta-analysis of three prospective randomized, controlled trials in which 658 patients with prehospital cardiac arrests were randomized to a brief period of CPR (90 to 180 seconds) prior to attempted defibrillation or to immediate defibrillation.

RESULTS: The mean EMS response times in the study groups varied from about 7 to about 12 minutes, and the duration of CPR prior to defibrillation in patients randomized to delayed defibrillation was 90 seconds in one study and 3 minutes in the remaining two. In a pooled analysis of results, there was no significant difference between the delayed or immediate CPR groups in rates of survival to hospital discharge overall (odds ratio [OR] 0.94, 95% CI 0.46-1.94), or in patient subgroups having EMS response times of less than five minutes (OR 0.70, 95% CI 0.24-2.08) or more than five minutes (OR 1.35, 95% CI 0.30-1.65), although one of the three studies reported a significant survival advantage of delayed defibrillation in this latter subgroup (OR 7.42, 95% CI 1.60-34.31).

CONCLUSIONS: There appears to be no evidence that providing a brief period of CPR prior to defibrillation significantly improves survival to discharge in adults sustaining prehospital cardiac arrest due to VF. There is, likewise, no evidence that this strategy is harmful. 13 references (psimpson@ambulance.nsw.gov.au – no reprints) Copyright 2011 by Emergency Medical Abstracts – All Rights Reserved 1/11 – #6