An alternative approach to advancing resuscitation science

Chest compression release velocity factors during out-of-hospital cardiac resuscitation

BACKGROUND

Higher chest compression release velocity (CCRV) has been associated with better outcomes after out-of-hospital cardiac arrest (OHCA), and patient factors have been associated with variations in chest wall compliance and compressibility. We evaluated whether patient sex, age, weight, and time in resuscitation were associated with CCRV during pre-hospital resuscitation from OHCA.

METHODS

Observational study of prospectively collected OHCA quality improvement data in two suburban EMS agencies in Arizona between 10/1/2008 and 12/31/2016. Subject-level mean CCRV during the first 10 min of compressions was correlated with categorical variables by the Wilcoxon rank-sum test and with continuous variables by the Spearman's rank correlation coefficient. Generalized estimating equation and linear mixed-effect models were used to study the trend of CCRV over time.

RESULTS

During the study period, 2535 adult OHCA cases were treated. After exclusion criteria, 1140 cases remained for analysis. Median duration of recorded compressions was 8.70 min during the first 10 min of CPR. An overall decline in CCRV was observed even after adjusting for compression depth. The subject-level mean CCRV was higher for minutes 0-5 than for minutes 5-10 (mean 347.9 mm/s vs. 339.0 mm/s, 95% CI of the difference -12.4 to -5.4, p < 0.0001). Males exhibited a greater mean CCRV compared to females [344.4 mm/s (IQR 307.3-384.6) vs. 331.5 mm/s (IQR 285.3-385.5), p = 0.013]. Mean CCRV was negatively correlated with age and positively correlated with patient weight.

CONCLUSION

CCRV declines significantly over the course of resuscitation. Patient characteristics including male sex, younger age, and increased weight were associated with a higher CCRV.

The mechanism of blood flow during chest compressions for cardiac arrest is probably influenced by the patient's chest configuration

Aim

Mechanical assist devices are sometimes needed during resuscitation efforts of patients with prolonged cardiac arrest. Two such devices, the AutoPulse and the LUCAS, have different mechanisms of action. We propose that the effectiveness of mechanical assist devices is somewhat dependent on the configuration and compliance of the patient's chest wall.

Methods

A previous study of patients with out‐of‐hospital cardiac arrest in Arizona reported that survivors were younger and many were observed to have narrow anterior–posterior chest diameters. These observations suggest that the predominant mechanism of blood flow during cardiopulmonary resuscitation of individuals with primary cardiac arrest is influenced by the patient's anterior–posterior chest diameter and compliance. It is proposed that in older individuals with an increased anterior–posterior chest diameter and decreased chest compliance that the AutoPulse, which works by increasing intrathoracic pressures, may be more effective. In contrast, the LUCAS device, which works predominately by compression of the sternum, is probably more effective in patients with narrower anterior–posterior diameters and a more compliant chest.

Results

These hypotheses need to be confirmed by researchers who not only have access to the lateral chest roentgenograms of patients with cardiac arrest, to determine their anterior–posterior chest diameter, but also to the type of mechanical device that was used during resuscitation efforts and their patient's survival. If the observations herein proposed are confirmed, hospitals and paramedics may ideally need to have one of each type of mechanical chest compression unit and select the one to use depending on the patient's age and anterior–posterior chest diameter.

Conclusions

The mechanism of blood flow in patients with cardiac arrest is predominantly secondary to cardiac compression in younger patients with narrow anterior chest diameters and predominately secondary to the thoracic pump mechanism in older patients with emphysema.

Automated external defibrillators in the hospital: A case of medical reversal

Automated external defibrillators (AEDs) emerged in the 1980s as an important innovation in pre-hospital emergency cardiac care (ECC). In the years since, the American Heart Association (AHA) and the International Liaison Committee for Resuscitation (ILCOR) have promoted AED technology for use in hospitals as well, resulting in the widespread purchase and use of AED-capable defibrillators. In-hospital use of AEDs now appears to have decreased survival from cardiac arrests. This article will look at the use of AEDs in hospitals as a case of "medical reversal." Medical reversal occurs when an accepted, widely used treatment is found to be ineffective or even harmful. This article will discuss the issue of AEDs in the hospital using a conceptual framework provided by recent work on medical reversal. It will go on to consider the implications of the reversal for in-hospital resuscitation programs and emergency medicine more generally.

Cardiocerebral and cardiopulmonary resuscitation - 2017 update

Sudden cardiac arrest is a major public health problem in the industrialized nations of the world. Yet, in spite of recurrent updates of the guidelines for cardiopulmonary resuscitation and emergency cardiac care, many areas have suboptimal survival rates. Cardiocerebral resuscitation, a non‐guidelines approach to therapy of primary cardiac arrest based on our animal research, was instituted in Tucson (AZ, USA) in 2002 and subsequently adopted in other areas of the USA. Survival rates of patients with primary cardiac arrest and a shockable rhythm significantly improved wherever it was adopted. Cardiocerebral resuscitation has three components: the community, the pre‐hospital, and the hospital. The community component emphasizes bystander recognition and chest compression only resuscitation. Its pre‐hospital or emergency medical services component emphasizes: (i) urgent initiation of 200 uninterrupted chest compressions before and after each indicated single defibrillation shock, (ii) delayed endotracheal intubation in favor of passive delivery of oxygen by a non‐rebreather mask, (iii) early adrenaline administration. The hospital component was added later. The national and international guidelines for cardiopulmonary resuscitation and emergency medical services are still not optimal, for several reasons, including the fact that they continue to recommend the same approach for two entirely different etiologies of cardiac arrest: primary cardiac arrest, often caused by ventricular fibrillation, where the arterial blood oxygenation is little changed at the time of the arrest, and secondary cardiac arrest from severe respiratory insufficiency, where the arterial blood is severely desaturated at the time of cardiac arrest. These different etiologies need different approaches to therapy.

Advancing resuscitation science

PURPOSE OF REVIEW

To describe an alternative approach for improving survival of patients with out-of-hospital cardiac arrest (OHCA). The survival of patients with OHCA has been poor and relatively unchanged for decades in spite of recurrent national and international guidelines. Although there are exceptions, many thought and continue to think that any change in the guidelines for cardiopulmonary resuscitation should be based on randomized controlled trials in humans. However, many factors, including the need for informed consent, the marked variability of patients, and the variability of the type and quality of bystander and advanced resuscitation efforts, all make such studies problematic. Thus, potentially life-saving procedures are often withheld for decades, resulting in unnecessary loss of life.

RECENT FINDINGS

Many improvements in public health conditions have been made using models of continuous quality improvement. When applied to resuscitation science, once baseline data are obtained, changes based on reliable experimental findings are instituted and outcomes measured. This approach has now been shown to result in significant improvement in neurologically intact survival of patients with OHCA.

SUMMARY

Following this model, we found significant improvement in survival of patients with a witnessed OHCA primary cardiac arrest.

The time dependent association of adrenaline administration and survival from out-of-hospital cardiac arrest

BACKGROUND

Recommended for decades, the therapeutic value of adrenaline (epinephrine) in the resuscitation of patients with out-of-hospital cardiac arrest (OHCA) is controversial.

PURPOSE

To investigate the possible time-dependent outcomes associated with adrenaline administration by Emergency Medical Services personnel (EMS).

METHODS

A retrospective analysis of prospectively collected data from a near statewide cardiac resuscitation database between 1 January 2005 and 30 November 2013. Multivariable logistic regression was used to analyze the effect of the time interval between EMS dispatch and the initial dose of adrenaline on survival. The primary endpoints were survival to hospital discharge and favourable neurologic outcome.

RESULTS

Data from 3469 patients with witnessed OHCA were analyzed. Their mean age was 66.3 years and 69% were male. An initially shockable rhythm was present in 41.8% of patients. Based on a multivariable logistic regression model with initial adrenaline administration time interval (AATI) from EMS dispatch as the covariate, survival was greatest when adrenaline was administered very early but decreased rapidly with increasing (AATI); odds ratio 0.94 (95% Confidence Interval (CI) 0.92-0.97). The AATI had no significant effect on good neurological outcome (OR=0.96, 95% CI=0.90-1.02).

CONCLUSIONS

In patients with OHCA, survival to hospital discharge was greater in those treated early with adrenaline by EMS especially in the subset of patients with a shockable rhythm. However survival rapidly decreased with increasing adrenaline administration time intervals (AATI).

Up-down hand position switch may delay the fatigue of non-dominant hand position rescuers and improve chest compression quality during cardiopulmonary resuscitation: a randomized crossover manikin study

Previous studies have shown improved external chest compression (ECC) quality and delayed rescuer fatigue when the dominant hand (DH) was in contact with the sternum. However, many rescuers prefer placing the non-dominant hand (NH) in contact with the sternum during ECC. We aimed to investigate the effects of up-down hand position switch on the quality of ECC and the fatigue of rescuers during cardiopulmonary resuscitation (CPR). After completion of a review of the standard adult basic life support (BLS) course, every candidate performed 10 cycles of single adult CPR twice on an adult manikin with either a constant hand position (CH) or a switched hand position (SH) in random order at 7-day intervals. The rescuers' general characteristics, hand positions, physiological signs, fatigue appearance and ECC qualities were recorded. Our results showed no significant differences in chest compression quality for the DH position rescuers between the CH and SH sessions (p>0.05, resp.). And also no significant differences were found for Borg score (p = 0.437) or cycle number (p = 0.127) of fatigue appearance after chest compressions between the two sessions. However, for NH position rescuers, the appearance of fatigue was delayed (p = 0.046), with a lower Borg score in the SH session (12.67 ± 2.03) compared to the CH session (13.33 ± 1.95) (p = 0.011). Moreover, the compression depth was significantly greater in the SH session (39.3 ± 7.2 mm) compared to the CH session (36.3 ± 8.1 mm) (p = 0.015). Our data suggest that the up-down hand position switch during CPR may delay the fatigue of non-dominant hand position rescuers and improve the quality of chest compressions.

Cardiocerebral Resuscitation: An Approach to Improving Survival of Patients With Primary Cardiac Arrest

Out-of-hospital cardiac arrest (OHCA) is a major public health problem. In the United States, OHCA accounts for more premature deaths than any other cause. For over a half-century, the national "Guidelines" for resuscitation have recommended the same initial treatment of primary and secondary cardiac arrests. Using this approach, the overall survival of patients with OHCA, while quite variable, was generally very poor. One reason is that the etiologies of cardiac arrests are not all the same. The vast majority of nontraumatic OHCA in adults are due to a "primary" cardiac arrest, rather than secondary to respiratory arrest. Decades of research and ongoing reviews of the literature led the University of Arizona Sarver Heart Center Resuscitation Research Group to conclude in 2003 that the national guidelines for patients with primary cardiac arrest were not optimal. Therefore, we instituted a new, nonguidelines approach to the therapy of primary cardiac arrest that dramatically improved survival. We called this approach cardiocerebral resuscitation (CCR), as it is the heart and the brain that are the most vulnerable and therefore need to be the focus of resuscitation efforts for these patients. In contrast, cardiopulmonary resuscitation should be reserved for respiratory arrests. Cardiocerebral resuscitation evolved into 3 components: the community, with emphasis for lay individuals to "Check, Call, Compress" and use an automated external defibrillator if available; the Emergency Medical Services, that emphasizes delayed intubation in favor of passive ventilation, urgent and near continuous chest compressions before and immediately after a single indicated shock, and the early administration of epinephrine; and the third component, added in 2007, the designations of hospitals in Arizona that request this designation and agree to receive patients with return of spontaneous circulation following OHCA and to institute state-of-the-art postresuscitation care that includes urgent therapeutic mild hypothermia and cardiac catheterization as a Cardiac Receiving Center. Each component of CCR is critical for optimal survival of patients with primary OHCA. In each city, county, and state where CCR was instituted, the result was a marked increase in survival of the subgroup of patients with OHCA most likely to survive, for example, those with a shockable rhythm. The purpose of this invited article on CCR is to review this alternative approach to resuscitation of patients with primary cardiac arrest and to encourage its adoption worldwide so that more lives can be saved.

Role of manual and mechanical chest compressions during resuscitation efforts throughout cardiac arrest

The previously published randomized trials of mechanical versus manual resuscitation of patients with cardiac arrest are inconclusive, but a recent systematic review concluded: "There is no evidence that mechanical cardiopulmonary resuscitation devices improve survival; to the contrary they may worsen neurological outcome." However, in our view, none of the randomized trials to date are definitive as the manual groups with primary cardiac arrest have not been treated optimally; that is, with minimally interrupted manual chest compressions, as advocated with cardiocerebral resuscitation. Since the mechanical chest compression devices work on different principles, it is possible that, while they may not be as effective and may even be worse in some subsets of patients, they may be preferable in others. Nevertheless, there are situations where manual chest compressions are not practical and, in these, mechanical devices may well be preferable. The Thumper® (Michigan Instruments, MI, USA) and the LUCAS™ (Jolife AB, Lund, Sweden) devices produce sternal compressions at 100 per min. By contrast, the AutoPulse® (ZOLL Circulation, CA, USA) produces chest compressions at a rate of only 80 per min. Since chest compression rate, as reviewed in this article, is important, one would guess that the devices that can produce a faster rate would be more effective. On the other hand, it could be that sternal compressions with manual or mechanical devices may be more or less effective depending on the arrested patient's chest configuration. We speculate that in the subset of patients with barrel chests, where sternal compressions are less likely to be operative, the AutoPulse might be more effective, but less effective in thin-chested individuals, where direct cardiac compression is the major mechanism of forward blood flow in the manual, Thumper and LUCAS methods. The original LUCAS device had the potential of active decompression as well as compression. To market in the USA, holes had to be placed in the 'suction cup'. It would be informative to know whether the original LUCAS device is more effective than the device in which the active decompression has been deactivated.

Use of cardiocerebral resuscitation or AHA/ERC 2005 Guidelines is associated with improved survival from out-of-hospital cardiac arrest: a systematic review and meta-analysis

OBJECTIVE

To determine whether the use of cardiocerebral resuscitation (CCR) or AHA/ERC 2005 Resuscitation Guidelines improved patient outcomes from out-of-hospital cardiac arrest (OHCA) compared to older guidelines.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE, EMBASE, Web of Science and the Cochrane Library databases. We also hand-searched study references and consulted experts.

STUDY SELECTION

Design: randomised controlled trials and observational studies.

POPULATION

OHCA patients, age >17 years.

COMPARATORS

'Control' protocol versus 'Study' protocol. 'Control' protocol defined as AHA/ERC 2000 Guidelines for cardiopulmonary resuscitation (CPR). 'Study' protocol defined as AHA/ERC 2005 Guidelines for CPR, or a CCR protocol.

OUTCOME

Survival to hospital discharge.

QUALITY

High-quality or medium-quality studies, as measured by the Newcastle Ottawa Scale using predefined categories.

RESULTS

Twelve observational studies met inclusion criteria. All the three studies using CCR demonstrated significantly improved survival compared to use of AHA 2000 Guidelines, as did five of the nine studies using AHA/ERC 2005 Guidelines. Pooled data demonstrate that use of a CCR protocol has an unadjusted OR of 2.26 (95% CI 1.64 to 3.12) for survival to hospital discharge among all cardiac arrest patients. Among witnessed ventricular fibrillation/ventricular tachycardia (VF/VT) patients, CCR increased survival by an OR of 2.98 (95% CI 1.92 to 4.62). Studies using AHA/ERC 2005 Guidelines showed an overall trend towards increased survival, but significant heterogeneity existed among these studies.

CONCLUSIONS

We demonstrate an association with improved survival from OHCA when CCR protocols or AHA/ERC 2005 Guidelines are compared to use of older guidelines. In the subgroup of patients with witnessed VF/VT, there was a threefold increase in OHCA survival when CCR was used. CCR appears to be a promising resuscitation protocol for Emergency Medical Services providers in increasing survival from OHCA. Future research will need to be conducted to directly compare AHA/ERC 2010 Guidelines with the CCR approach.

The cardiocerebral resuscitation protocol for treatment of out-of-hospital primary cardiac arrest

Out-of-hospital cardiac arrest (OHCA) is a significant public health problem in most westernized industrialized nations. In spite of national and international guidelines for cardiopulmonary resuscitation and emergency cardiac care, the overall survival of patients with OHCA was essentially unchanged for 30 years--from 1978 to 2008 at 7.6%. Perhaps a better indicator of Emergency Medical System (EMS) effectiveness in treating patients with OHCA is to focus on the subgroup that has a reasonable chance of survival, e.g., patients found to be in ventricular fibrillation (VF). But even in this subgroup, the average survival rate was 17.7% in the United States, unchanged between 1980 and 2003, and 21% in Europe, unchanged between 1980 and 2004. Prior to 2003, the survival of patients with OHCA, in VF in Tucson, Arizona was less than 9% in spite of incorporating previous guideline recommendations. An alternative (non-guidelines) approach to the therapy of patients with OHCA and a shockable rhythm, called Cardiocerebral Resuscitation, based on our extensive physiologic laboratory studies, was introduced in Tucson in 2003, in rural Wisconsin in 2004, and in selected EMS areas in the metropolitan Phoenix area in 2005. Survival of patients with OHCA due to VF treated with Cardiocerebral Resuscitation in rural Wisconsin increased to 38% and in 60 EMS systems in Arizona to 39%. In 2004, we began a statewide program to advocate chest compression-only CPR for bystanders of witnessed primary OHCA. Over the next five years, we found that survival of patients with a shockable rhythm was 17.7% in those treated with standard bystander CPR (mouth-to-mouth ventilations plus chest compression) compared to 33.7% for those who received bystander chest-compression-only CPR. This article on Cardiocerebral Resuscitation, by invitation following a presentation at the 2011 Danish Society Emergency Medical Conference, summarizes the results of therapy of patients with primary OHCA treated with Cardiocerebral Resuscitation, with requested emphasis on the EMS protocol.

The hospital's role in improving survival of patients with out-of-hospital cardiac arrest

Out-of-hospital cardiac arrest (OHCA) is a major public health problem. Unfortunately, in spite of recurring updated guidelines, survival of patients with OHCA had been unchanged for decades. Recently, new approaches to patients with OHCA during the community and prehospital phases of therapy for cardiac arrest have resulted in a dramatic improvement in survival. Further improvement in survival has resulted from hospitals designated as Cardiac Receiving Centers. These centers are committed to the treatment of post-cardiac arrest syndrome by providing 24/7 therapeutic mild hypothermia, urgent cardiac catheterization and percutaneous coronary intervention, evidence-based termination of resuscitation protocols that limit premature withdrawal of care, protocol to address organ donation, commitment of cardiocerebral resuscitation training in their community, and a commitment and proven ability of data collection to assure that instituted changes result in improved survival. This newer aspect of hospital practice is an aspect that needs to be embraced by either becoming a Cardiac Receiving Center or partnering with other hospitals that can provide this critically important service.

Epinephrine improves 24-hour survival in a swine model of prolonged ventricular fibrillation demonstrating that early intraosseous is superior to delayed intravenous administration

BACKGROUND

Vasopressors administered IV late during resuscitation efforts fail to improve survival. Intraosseous (IO) access can provide a route for earlier administration. We hypothesized that IO epinephrine after 1 minute of cardiopulmonary resuscitation (CPR) (an "optimal" IO scenario) after 10 minutes of untreated ventricular fibrillation (VF) cardiac arrest would improve outcome in comparison with either IV epinephrine after 8 minutes of CPR (a "realistic" IV scenario) or placebo controls with no epinephrine.

METHODS

Thirty swine were randomized to IO epinephrine, IV epinephrine, or placebo. Important outcomes included return of spontaneous circulation (ROSC), 24-hour survival, and 24-hour survival with good neurological outcome (cerebral performance category 1).

RESULTS

ROSC after 10 minutes of untreated VF was uncommon without administration of epinephrine (1 of 10), whereas ROSC was nearly universal with IO epinephrine or delayed IV epinephrine (10 of 10 and 9 of 10, respectively; P = 0.001 for either versus placebo). Twenty-four hour survival was substantially more likely after IO epinephrine than after delayed IV epinephrine (10 of 10 vs. 4 of 10, P = 0.001). None of the placebo group survived at 24 hours. Survival with good neurological outcome was more likely after IO epinephrine than after placebo (6 of 10 vs. 0 of 10, P = 0.011), and only 3 of 10 survived with good neurological outcome in the delayed IV epinephrine group (not significant versus either IO or placebo).

CONCLUSION

In this swine model of prolonged VF cardiac arrest, epinephrine administration during CPR improved outcomes. In addition, early IO epinephrine improved outcomes in comparison with delayed IV epinephrine.

An observational study to assess changes in arterial blood gas values during untreated porcine ventricular fibrillation

BACKGROUND

Cardiocerebral resuscitation (CCR) is reportedly superior to cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) even though active ventilation is not initially provided. Understandably, concerns have been raised regarding the withholding of positive pressure ventilation (PPV) during CCR because of the longstanding belief that respiratory gas exchange is a critical action during resuscitation.

OBJECTIVE

In this observational study, we sought to quantify the effect of prolonged untreated ventricular fibrillation (VF) on arterial pH, partial pressure of carbon dioxide (pCO(2)), and partial pressure of oxygen (pO(2)) values in a swine model of witnessed cardiac arrest to begin exploring the validity of these concerns.

METHODS

Both included studies were approved by the institutional animal care and use committee (IACUC). Eighty-three animals (25-35 kg) were instrumented under general anesthesia. Baseline characteristics were recorded. An arterial blood gas (ABG) sample was drawn from each animal via femoral catheter just prior to electrical induction of VF. After 8 minutes of untreated VF in one study (study 1 [n = 30]) and 10 minutes of untreated VF in the other study (study 2 [n = 53]), a second ABG sample was drawn. All samples were processed immediately using an i-STAT portable whole blood analyzer. Baseline characteristics of animals in the two studies were assessed using descriptive statistics. For the second ABG sample in each study, the mean pH, pCO(2), and pO(2) values, with 95% confidence intervals (95% CIs), were determined. The paired ABG results for each animal were then compared and the average pH, pCO(2), and pO(2) proportions, with 95% CIs, for each study were calculated.

RESULTS

The baseline characteristics of the animals in the two studies were similar. After 8 and 10 minutes of untreated VF cardiac arrest, the pH values were 7.35 (95% CI = 7.32, 7.37) and 7.37 (95% CI = 7.36, 7.38), the pCO(2) increased to 44.1 mmHg (95% CI = 41.1, 47.1) and 52.7 mmHg (95% CI = 51.0, 54.4), and the pO(2) decreased to 44.8 mmHg (95% CI = 42.2, 47.4) and 45.5 mmHg (95% CI = 43.3, 47.6), respectively.

CONCLUSIONS

Using our swine model of witnessed cardiac arrest with prolonged untreated VF, the arterial pH remained essentially unchanged and the pCO(2) increased to 1.42 times baseline after 10 minutes, while almost half of the initial O(2) concentration in the blood at the beginning of resuscitation remained.

Epinephrine in resuscitation: curse or cure?

The use of epinephrine during cardiac arrest has been advocated for decades and forms an integral part of the published guidelines. Its efficacy is supported by animal data, but human trial evidence is lacking. This is partly attributable to disparities in trial methodology. Epinephrine’s pharmacologic and physiologic effects include an increase in coronary perfusion pressure that is key to successful resuscitation. One possible explanation for the lack of epinephrine’s demonstrated efficacy in human trials of out-of-hospital cardiac arrest is the delay in its administration. A potential solution may be intraosseus epinephrine, which can be administered quicker. More importantly, it is the quality of the basic life support, early and uninterrupted chest compressions, early defibrillation and postresuscitation care that will provide the best chance of neurologically intact survival.

Cardiocerebral resuscitation is associated with improved survival and neurologic outcome from out-of-hospital cardiac arrest in elders

BACKGROUND

Recent studies have shown that a new emergency medical services (EMS) protocol for treating patients who suffer out-of-hospital cardiac arrest (OHCA), cardiocerebral resuscitation (CCR), significantly improves survival compared to standard advanced life support (ALS). However, due to their different physiology, it is unclear if all elders, or any subsets of elders who are OHCA victims, would benefit from the CCR protocol.

OBJECTIVES

The objectives of this analysis were to compare survival by age group for patients receiving CCR and ALS, to evaluate their neurologic outcome, and to determine what other factors affect survival in the subset of patients who do receive CCR.

METHODS

An analysis was performed of 3,515 OHCAs occurring between January 2005 and September 2008 in the Save Hearts in Arizona Registry. A total of 1,024 of these patients received CCR. Pediatric patients and arrests due to drowning, respiratory, or traumatic causes were excluded. The registry included data from 62 EMS agencies, some of which instituted CCR. Outcome measures included survival to hospital discharge and cerebral performance category (CPC) scores. Logistic regression evaluated outcomes in patients who received CCR versus standard ALS across age groups, adjusted for known potential confounders, including bystander cardiopulmonary resuscitation (CPR), witnessed arrest, EMS dispatch-to-arrival time, ventricular fibrillation (Vfib), and agonal respirations on EMS arrival. Predictors of survival evaluated included age, sex, location, bystander CPR, witnessed arrest, Vfib/ventricular tachycardia (Vtach), response time, and agonal breathing, based on bivariate results. Backward stepwise selection was used to confirm predictors of survival. These predictors were then analyzed with logistic regression by age category per 10 years of age.

RESULTS

Individuals who received CCR had better outcomes across age groups. The increase in survival for the subgroup with a witnessed Vfib was most prominent on those<40 years of age (3.7% for standard ALS patients vs. 19% for CCR patients, odds ratio [OR]=5.94, 95% confidence interval [CI]=1.82 to 19.26). This mortality benefit declined with age until the >or=80 years age group, which regained the benefit (1.8% vs. 4.6%, OR=2.56, 95% CI=1.10 to 5.97). Neurologic outcomes were also better in the patients who received CCR (OR=6.64, 95% CI=1.31 to 32.8). Within the subgroup that received CCR, the factors most predictive of improved survival included witnessed arrest, initial rhythm of Vfib/Vtach, agonal respirations upon arrival, EMS response time, and age. Neurologic outcome was not adversely affected by age.

CONCLUSIONS

Cardiocerebral resuscitation is associated with better survival from OHCA in most age groups. The majority of patients in all age groups who survived to hospital discharge and who could be reached for follow-up had good neurologic outcome. Among patients receiving CCR for OHCA, witnessed arrest, Vfib/Vtach, agonal respirations, and early response time are significant predictors of survival, and these do not change significantly based on age.

Ventilation during resuscitation efforts for out-of-hospital primary cardiac arrest

PURPOSE OF REVIEW

To discuss recent findings surrounding the role of ventilation during cardiopulmonary resuscitation for individuals with out-of-hospital primary cardiac arrest.

RECENT FINDINGS

Active assisted ventilation during primary cardiac arrest may not always be beneficial and, in some circumstances, may lead to worse outcomes. By interrupting chest compressions and thereby decreasing vital organ perfusion, rescue breathing may be deleterious. In addition to the time required to administer breaths, the delay due to the insertion of advanced airways, even by well trained individuals, is often extensive. Furthermore, once intubation is completed, excessive hyperventilation occurs frequently, even by recently trained medical providers. Although most experts agree that excessive ventilation is harmful during out-of-hospital cardiac resuscitation, the optimal rate, tidal volume, timing, and technique of ventilation is still unknown. There is increasing evidence that, in patients with witnessed arrests and a shockable rhythm, the optimal form of ventilation is passive oxygen insufflation.

SUMMARY

Assisted ventilation during the initial provision of cardiopulmonary resuscitation is less important than previously believed. It is hypothesized that, by training prehospital medical providers to utilize passive oxygen insufflation for individuals with primary cardiac arrest, critical organ perfusion will increase and, therefore, survival after out-of-hospital cardiac arrest will improve.

Evolution and new perspective of chest compression mechanical devices

Cardiac arrest is a major concern in health care, owing to its high incidence and mortality rates. Since the development of external cardiopulmonary resuscitation (CPR), there has been little advancement in nonpharmacologic therapies that have increased survival rates associated with cardiac arrest. Consequently, there has been much interest in the development of new techniques to improve the efficacy of CPR, particularly in the development of devices. Initially, many of the devices developed were not considered functional and failed to gain acceptance in the clinical setting. Recently, however, several devices have been developed which have progressed the administration of CPR and garnered acceptance in the clinical setting. In this article we will briefly review some of the more common mechanical devices developed to increase the safety and efficacy of CPR administration.

Preshock cardiopulmonary resuscitation worsens outcome from circulatory phase ventricular fibrillation with acute coronary artery obstruction in swine

BACKGROUND

Some clinical studies have suggested that chest compressions before defibrillation improve survival in cardiac arrest because of prolonged ventricular fibrillation (VF; ie, within the circulatory phase). Animal data have also supported this conclusion, and we have previously demonstrated that preshock chest compressions increase the VF median frequency and improve the likelihood of a return of spontaneous circulation in normal swine. We hypothesized that chest compressions before defibrillation in a swine model of acute myocardial ischemia would also increase VF median frequency and improve resuscitation outcome.

METHODS AND RESULTS

Twenty-six swine were subjected to balloon occlusion of the left anterior descending coronary artery for 2 hours. The balloon was removed and VF was induced and untreated for 8 minutes. Swine were then treated with up to 3 stacked defibrillation shocks (n=13, shock-first group) or 3 minutes of chest compressions before shock (n=13, preshock cardiopulmonary resuscitation group). In the preshock cardiopulmonary resuscitation group, median frequency was increased from 7.0+/-0.8 to 13.9+/-1.6 Hz after chest compressions (P=0.002). Despite the improved median frequency in the preshock cardiopulmonary resuscitation group, 24-hour survival with favorable neurological status was significantly worse in the preshock cardiopulmonary resuscitation group (1/13) compared with the shock-first group (8/13, P=0.01).

CONCLUSIONS

In a swine model of prolonged VF in acute myocardial ischemia, 24-hour survival with favorable neurological status was more likely when defibrillation was performed first without preceding chest compressions. Myocardial substrate is an important factor in determining the optimal resuscitation strategy.

Immediate post-shock chest compressions improve outcome from prolonged ventricular fibrillation

AIM

This study was designed to test the hypothesis that immediate post-shock chest compressions improve outcome from prolonged ventricular fibrillation (VF) compared with typical "hands off" period (i.e., delayed post-shock compressions) associated with AED use.

MATERIALS AND METHODS

After 7.5 min of untreated VF, 36 domestic swine (26+/-1 kg) were treated with 200 J biphasic shocks and randomly assigned to: (1) 1 min of immediate post-shock chest compressions or (2) simulated pre-hospital automated external defibrillator (AED) care with delays in post-shock chest compressions. Return of spontaneous circulation (ROSC) occurred in 7/18 immediate chest compressions animals within 2 min of the first shock versus 0/18 AED animals (P<0.01). Ten of 18 immediate chest compressions animals attained ROSC compared with 3/18 AED animals (P<0.05). Nine of 18 immediate chest compressions swine were alive at 24 and 48 h compared with 3/18 AED swine (P<0.05). All 48-h survivors had good neurologic outcomes. Among the 21 animals that defibrillated with the first shock, ROSC was attained in 7/10 immediate chest compressions animals within 2 min of the first shock compared with 0/11 AED animals (P=0.001), and 48-h survival was attained in 8/10 versus 3/11, respectively (P<0.05).

CONCLUSIONS

Immediate post-shock chest compressions can substantially improve outcome from prolonged VF compared with simulated pre-hospital AED care.

Continuous passive oxygen insufflation results in a similar outcome to positive pressure ventilation in a swine model of out-of-hospital ventricular fibrillation

BACKGROUND

The deleterious effects of positive pressure ventilation may be prevented by substituting passive oxygen insufflation during advanced cardiac life support (ACLS) cardiopulmonary resuscitation (CPR).

METHODS

We compared 24-h neurologically normal survival among three different ventilation scenarios for ACLS in a realistic swine model of out-of-hospital prolonged ventricular fibrillation (VF) cardiac arrest. No bystander CPR was provided during the first 8 min of untreated VF before the simulated arrival of an emergency medical system (EMS). Thirty-six swine were randomly assigned to one of three experimental groups. Group I (standard ventilation) was mechanically ventilated at 10 respirations per minute (RPM) at a tidal volume (TV) of 10 ml/kg with 100% oxygen. Group II (hyperventilation) was ventilated at 35 RPM at a TV of 20 ml/kg with 100% oxygen. In Group III (insufflation) animals, a nasal cannula was placed in the oropharynx to administer oxygen continuously at 10 l/min.

RESULTS

There was no significant difference in the 24h neurologically normal survival among groups (standard: 2/12, hyperventilation: 2/12, insufflation: 4/12; p=.53).

CONCLUSIONS

Passive insufflation may be an acceptable alternative to the currently recommended positive pressure ventilation during resuscitation efforts for out-of-hospital VF cardiac arrest. Potential advantages of this technique include: (1) easier to teach, (2) easier to administer, (3) prevention of the adverse effects of positive pressure ventilation and (4) allows EMS personnel to concentrate upon other critically important duties.

The effect of hydrocortisone on the outcome of out-of-hospital cardiac arrest patients: a pilot study

OBJECTIVE

Several studies have disclosed the importance of serum adrenocorticotropic hormone and cortisol levels in resuscitation. The objective of this study was to observe the effect of hydrocortisone on the outcome of out-of-hospital cardiac arrest (OHCA) patients.

DESIGN

Prospective, nonrandomized, open-labeled clinical trial.

SETTING

Emergency department (ED) of National Taiwan University Hospital.

PATIENTS AND PARTICIPANTS

Ninety-seven nontraumatic adult OHCA victims.

INTERVENTIONS

Serum adrenocorticotropic hormone and total cortisol levels were examined in all patients. The hydrocortisone group (n = 36) received 100 mg intravenous hydrocortisone during resuscitation, and the nonhydrocortisone group (n = 61) received 0.9% saline as placebo.

MEASUREMENTS AND RESULTS

Comparison of return of the spontaneous circulation (ROSC) rates between the 2 groups was analyzed. The hydrocortisone group had a significantly higher ROSC rate than the nonhydrocortisone group (61% vs 39%, P = .038). Hydrocortisone administration within 6 minutes after ED arrival led to an increased ROSC rate (90% vs 50%, P = .045). The hydrocortisone and nonhydrocortisone groups did not differ in the development of electrolyte disturbances, gastrointestinal tract bleeding, or infection during early postresuscitation period (gastrointestinal bleeding: 41% vs 46%, P = .89; infection: 50% vs 75%, P = .335). There was no significant difference between the hydrocortisone and nonhydrocortisone groups in terms of 1- and 7-day survival and hospital discharge rates.

CONCLUSIONS

Hydrocortisone treatment during resuscitation, particularly when administrated within 6 minutes of ED arrival, may be associated with an improved ROSC rate in OHCA patients.

Implementation of a standardised treatment protocol for post resuscitation care after out-of-hospital cardiac arrest

BACKGROUND

Mortality among patients admitted to hospital after out-of-hospital cardiac arrest (OHCA) is high. Based on recent scientific evidence with a main goal of improving survival, we introduced and implemented a standardised post resuscitation protocol focusing on vital organ function including therapeutic hypothermia, percutaneous coronary intervention (PCI), control of haemodynamics, blood glucose, ventilation and seizures.

METHODS

All patients with OHCA of cardiac aetiology admitted to the ICU from September 2003 to May 2005 (intervention period) were included in a prospective, observational study and compared to controls from February 1996 to February 1998.

RESULTS

In the control period 15/58 (26%) survived to hospital discharge with a favourable neurological outcome versus 34 of 61 (56%) in the intervention period (OR 3.61, CI 1.66-7.84, p=0.001). All survivors with a favourable neurological outcome in both groups were still alive 1 year after discharge. Two patients from the control period were revascularised with thrombolytics versus 30 (49%) receiving PCI treatment in the intervention period (47 patients (77%) underwent cardiac angiography). Therapeutic hypothermia was not used in the control period, but 40 of 52 (77%) comatose patients received this treatment in the intervention period.

CONCLUSIONS

Discharge rate from hospital, neurological outcome and 1-year survival improved after standardisation of post resuscitation care. Based on a multivariate logistic analysis, hospital treatment in the intervention period was the most important independent predictor of survival.

Analysis of the ventricular fibrillation waveform in refibrillation

OBJECTIVES

Frustrating outcomes are driving investigation of alternative resuscitation protocols. Previous analysis of the ventricular fibrillation (VF) waveform has focused on guiding whether to shock immediately or to delay for delivery of cardiopulmonary resuscitation in the case of presenting VF. The same issues emerge in the case of refibrillation.

MEASUREMENTS AND MAIN RESULTS

All cases of witnessed VF cardiac arrest in the Rochester, MN, area in a 9-yr period were analyzed. Rochester rescuers employed an early defibrillation protocol during the study period. A summary measure of the VF waveform before the shock delivered in 35 incidents of refibrillation was compared with the time elapsed from the initial shock, the intervening electrocardiographic rhythm, ambulance response time, and call-to-shock time for prediction of early return of spontaneous circulation and of neurologically intact survival. VF waveform analysis separated patients with good outcomes when treated with early defibrillation of refibrillation from those without good outcomes more clearly than other predictors.

CONCLUSIONS

Analysis of VF waveform offers promise for real-time guidance of resuscitation efforts on the basis of individual patient characteristics, in refibrillation and in the initial shock. It has advantages over guidance based on individual or aggregate system response times.

Rescuer fatigue: standard versus continuous chest-compression cardiopulmonary resuscitation

OBJECTIVES

Continuous chest-compression cardiopulmonary resuscitation (CCC-CPR) has been advocated as an alternative to standard CPR (STD-CPR). Studies have shown that CCC-CPR delivers substantially more chest compressions per minute and is easier to remember and perform than STD-CPR. One concern regarding CCC-CPR is that the rescuer may fatigue and be unable to maintain adequate compression rate or depth throughout an average emergency medical services response time. The specific aim of this study was to compare the effects of fatigue on the performance of CCC-CPR and STD-CPR on a manikin model.

METHODS

This was a prospective, randomized crossover study involving 53 medical students performing CCC-CPR and STD-CPR on a manikin model. Students were randomized to their initial CPR group and then performed the other type of CPR after a period of at least two days. Students were evaluated on their performance of 9 minutes of CPR for each method. The primary endpoint was the number of adequate chest compressions (at least 38 mm of compression depth) delivered per minute during each of the 9 minutes. The secondary endpoints were total compressions, compression rate, and the number of breaks taken for rest. The students' performance was evaluated on the basis of Skillreporter Resusci Anne (Laerdal, Wappingers Falls, NY) recordings. Primary and secondary endpoints were analyzed by using the generalized linear mixed model for counting data.

RESULTS

In the first 2 minutes, participants delivered significantly more adequate compressions per minute with CCC-CPR than STD-CPR, (47 vs. 32, p = 0.004 in the 1st minute and 39 vs. 29, p = 0.04 in the 2nd minute). For minutes 3 through 9, the differences in number of adequate compressions between groups were not significant. Evaluating the 9 minutes of CPR as a whole, there were significantly more adequate compressions in CCC-CPR vs. STD-CPR (p = 0.0003). Although the number of adequate compressions per minute declined over time in both groups, the rate of decline was significantly greater in CCC-CPR compared with STD-CPR (p = 0.0003). The mean number of total compressions delivered in the first minute was significantly greater with CCC-CPR than STD-CPR (105 per minute vs. 58 per minute, p < 0.001) and did not change over 9 minutes in either group. There were no differences in compression rates or number of breaks between groups.

CONCLUSIONS

CCC-CPR resulted in more adequate compressions per minute than STD-CPR for the first 2 minutes of CPR. However, the difference diminished after 3 minutes, presumably as a result of greater rescuer fatigue with CCC-CPR. Overall, CCC-CPR resulted in more total compressions per minute than STD-CPR during the entire 9 minutes of resuscitation.

Inter-rater reliability for witnessed collapse and presence of bystander CPR

OBJECTIVE

Witnessed collapse and bystander CPR are the variables most frequently associated with good outcome from out-of-hospital cardiac arrest (OOHCA). The reliability of abstracting witnessed collapse and bystander CPR from prehospital Emergency Medical Services (EMS) patient care records (PCRs) is not known. We sought to determine the inter-rater reliability for different methods of ascertaining and defining witnessed collapse and performance of bystander CPR.

METHODS

A sample of 100 PCRs for patients with OOHCA was selected at random from a pool of 325 PCRs between May 2003 and January 2005. Paramedics used a drop down menu to indicate witnessed collapse and bystander CPR, and completed a narrative description of the event. An on-scene EMS physician also completed a data sheet. The PCR was examined by two separate evaluators to determine the presence of witnessed collapse and bystander CPR. A consensus was reached by three other reviewers using all available data sources. Inter-rater agreement was quantified using the unweighted kappa statistic.

RESULTS

For witnessed collapse, there is substantial agreement between the following: individual evaluators (kappa=0.76, S.D.=0.07), individual evaluators and consensus group (kappa=0.61, S.D.=0.07 and 0.66, S.D.=0.07), and physician and consensus group (kappa=0.68, S.D.=0.08). Agreement between individual evaluators and the physician was fair to moderate (kappa=0.38, S.D.=0.07 and 0.44, S.D.=0.07). Agreement between individual evaluators, physician, consensus group and the PCR drop down menu was fair to moderate (kappa range 0.33, S.D.=0.09 to 0.54, S.D.=0.09). For bystander CPR, there is substantial agreement between the individual evaluators and the consensus group (kappa=0.64, S.D.=0.07 and 0.63, S.D.=0.06) and between the physician and the consensus group (kappa=0.61, S.D.=0.08). Agreement between the two individual evaluators is moderate (kappa=0.59, S.D.=0.07). Agreement between the physician and individual evaluators is fair (kappa=0.36, S.D.=0.07 and 0.38, S.D.=0.07). The PCR drop down menu had moderate to substantial agreement with the individual evaluators, physician, and consensus group (kappa range 0.50, S.D.=0.09 to 0.75, S.D.=0.09).

CONCLUSIONS

Determination of witnessed collapse and bystander CPR during OOHCA may be less reliable than previously thought, and differences between methods of rating could influence study results.