Importance of continuous chest compressions during cardiopulmonary resuscitation: improved outcome during a simulated single lay-rescuer scenario

Airway management in cardiac arrest

Airway management has been emphasized as crucial to effective resuscitation of patients in cardiac arrest. However, recent research has shown that coronary and cerebral perfusion should be prioritized rather than airway management. Endotracheal intubation has been deemphasized. This article reviews the current state of the literature regarding airway management of the patient in cardiac arrest. Ventilatory management strategies are also discussed.

Improving bystander cardiopulmonary resuscitation

PURPOSE OF REVIEW

Summary estimates indicate that bystander cardiopulmonary resuscitation (CPR) can improve the chances of out-of-hospital cardiac arrest survival two-fold to three-fold. And yet, only a minority of arrest victims receive bystander CPR. This summary will review the challenges and approaches to achieve early and effective bystander CPR.

RECENT FINDINGS

Given the host of barriers, a successful strategy to improve bystander CPR must enable more timely and comprehensive arrest identification, encourage and empower bystanders to act, and help assure effective CPR. Arrest identification can be simplified so that bystanders should start CPR when a person is unconscious and not breathing normally. Evidence from observational studies and interventional trials supports the effectiveness of chest compression-only CPR for bystanders. As a consequence, the emphasis of bystander CPR training has been modified to feature and assure chest compressions. Bystanders should initiate CPR with compressions and consider the addition of rescue breathing based on their CPR training and skills as well as special circumstances of the victim. Bystander CPR training has evolved to incorporate this emphasis. Although general community-level CPR training remains a cornerstone strategy, training directed to those most likely to witness an arrest also has a useful role. In particular, 'just-in-time' dispatcher-assisted CPR instruction can increase bystander CPR and improve the likelihood of survival.

SUMMARY

Recent developments in bystander CPR have simplified arrest recognition and improved CPR training, while retaining CPR effectiveness. The goal of these developments is to increase and improve bystander CPR and in turn improve resuscitation.

Perishock pause: an independent predictor of survival from out-of-hospital shockable cardiac arrest

BACKGROUND

Perishock pauses are pauses in chest compressions before and after defibrillatory shock. We examined the relationship between perishock pauses and survival to hospital discharge.

METHODS AND RESULTS

We included out-of-hospital cardiac arrest patients in the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest who suffered arrest between December 2005 and June 2007, presented with a shockable rhythm (ventricular fibrillation or pulseless ventricular tachycardia), and had cardiopulmonary resuscitation process data for at least 1 shock (n=815). We used multivariable logistic regression to determine the association between survival and perishock pauses. In an analysis adjusted for Utstein predictors of survival, the odds of survival were significantly lower for patients with preshock pause ≥20 seconds (odds ratio, 0.47; 95% confidence interval, 0.27 to 0.82) and perishock pause ≥40 seconds (odds ratio, 0.54; 95% confidence interval, 0.31 to 0.97) compared with patients with preshock pause <10 seconds and perishock pause <20 seconds. Postshock pause was not independently associated with a significant change in the odds of survival. Log-linear modeling depicted a decrease in survival to hospital discharge of 18% and 14% for every 5-second increase in both preshock and perishock pause interval (up to 40 and 50 seconds, respectively), with no significant association noted with changes in the postshock pause interval.

CONCLUSIONS

In patients with cardiac arrest presenting in a shockable rhythm, longer perishock and preshock pauses were independently associated with a decrease in survival to hospital discharge. The impact of preshock pause on survival suggests that refinement of automatic defibrillator software and paramedic education to minimize preshock pause delays may have a significant impact on survival.

Blood pressure during resuscitation in man--the effect of pause during rhythm analysis revisited

AIMS

This study reports invasive arterial pressures before and after the rhythm analysing pauses during CPR and evaluates the possible association of the quality of CPR and the length of the pause with blood pressure around the pause.

MATERIALS AND METHODS

Five patients who experienced out-of hospital or in-hospital cardiac arrest were included in the study. Using a monitor/defibrillator with sensing capabilities, the parameters of CPR quality including chest compression depth, rate, force and the duration of interruption were recorded and compared to blood pressure.

RESULTS

Altogether 42 pauses were observed in five patients with a duration of 9±5 s (mean±SD). The values for systolic (SAP), mean (MAP) and diastolic arterial pressures (DAP) were 107±30, 44±12 and 14±12 mmHg before the pause and 119±34, 49±13 and 14±14 mmHg after the pause, respectively. There was a statistically significant increase in both SAP (12.1±28.2 mmHg; p=0.021) and MAP (4.2±8.7 mmHg (p=0.008) and the duration of the pause was identified as an independent factor for that in a linear mixed model. The pause duration up to ten seconds maintained the pressure achieved if the compression depth was immediately according to the guidelines (p=0.046).

CONCLUSIONS

Contrary to the previous animal studies, this preliminary study in humans demonstrates that blood pressures achieved before the rhythm analysis pause do not necessarily decrease after the pause but may even increase if the duration of the pause is under ten seconds and the quality of CPR is good both before and after the pause.

End-tidal CO₂ detection of an audible heart rate during neonatal cardiopulmonary resuscitation after asystole in asphyxiated piglets

Even brief interruption of cardiac compressions significantly reduces critical coronary perfusion pressure during cardiopulmonary resuscitation (CPR). End-tidal CO₂ (ETCO₂) monitoring may provide a continuous noninvasive method of assessing return of spontaneous circulation (ROSC) without stopping to auscultate for heart rate (HR). However, the ETCO₂ value that correlates with an audible HR is unknown. Our objective was to determine the threshold ETCO₂ that is associated with ROSC after asphyxia-induced asystole. Neonatal swine (n = 46) were progressively asphyxiated until asystole occurred. Resuscitation followed current neonatal guidelines with initial ventilation with 100% O₂ followed by cardiac compressions followed by epinephrine for continued asystole. HR was auscultated every 30 s, and ETCO₂ was continuously recorded. A receiver operator curve was generated using the calculated sensitivity and specificity for various ETCO₂ values, where a positive test was defined as the presence of HR >60 bpm by auscultation. An ETCO₂ cut-off value of 14 mm Hg is the most sensitive ETCO₂ value with the least false positives. When using ETCO₂ to guide uninterrupted CPR in this model of asphyxia-induced asystole, auscultative confirmation of return of an adequate HR should be performed when ETCO₂ ≥ 14 mm Hg is achieved. Correlation during human neonatal CPR needs further investigation.

An algorithm used for ventricular fibrillation detection without interrupting chest compression

Ventricular fibrillation (VF) is the primary arrhythmic event in the majority of patients suffering from sudden cardiac arrest. Attention has been focused on this particular rhythm since it is recognized that prompt therapy, especially electrical defibrillation, may lead to a successful outcome. However, current versions of automated external defibrillators (AEDs) mandate repetitive interruptions of chest compression for rhythm analyses since artifacts produced by chest compression during cardiopulmonary resuscitation (CPR) preclude reliable electrocardiographic (ECG) rhythm analysis. Yet, repetitive interruptions in chest compression are detrimental to the success of defibrillation. The capability for rhythm analysis without requiring "hands-off" intervals will allow for more effective resuscitation. In this paper, a novel continuous-wavelet-transformation-based morphology consistency evaluation algorithm was developed for the detection of disorganized VF from organized sinus rhythm (SR) without interrupting the ongoing chest compression. The performance of this method was evaluated on both uncorrupted and corrupted ECG signals recorded from AEDs obtained from out-of-hospital victims of cardiac arrest. A total of 232 patients and 31,092 episodes of either VF or SR were accessed, in which 8195 episodes were corrupted by artifacts produced by chest compressions. We also compared the performance of this method with three other established algorithms, including VF filter, spectrum analysis, and complexity measurement. Even though there was a modest decrease in specificity and accuracy when chest compression artifact was present, the performance of this method was still superior to other reported methods for VF detection during uninterrupted CPR.

The frequency and consequences of cardiopulmonary resuscitation performed by bystanders on patients who are not in cardiac arrest

BACKGROUND

The American Heart Association encourages trained and untrained bystanders to perform, at a minimum, chest compressions on anyone who suddenly collapses. It is possible that people who are not in cardiac arrest may receive bystander cardiopulmonary resuscitation (CPR), from which the potential for injury is unknown.

OBJECTIVES

To determine the number of victims who received bystander CPR but were not in cardiac arrest and to identify any injuries resulting from receiving bystander CPR.

METHODS

Retrospective review of patient care records from a countywide emergency medical services (EMS) database. All patients treated by EMS between March 2003 and February 2009 who received bystander CPR were queried. Victims who were determined not to be in cardiac arrest upon EMS personnel assessment were identified as likely not in cardiac arrest. Hospital medical records for transported patients were reviewed for injuries possibly related to CPR. Patient demographics were collected and descriptive statistics were used for analysis.

RESULTS

Six hundred seventy-two incidents of bystander CPR occurred, with 77 (11.5%) cases not being identified as cardiac arrests by EMS. Twenty-three percent of the patients were less than 19 years of age. Emergency medical services arrived in less than 6 minutes for 68% of patients. Seventy-two patients were evaluable for injury; of those, 53% were admitted to the intensive care unit. One patient (1.4%) had an injury that was documented in the medical record as possibly CPR-related: rhabdomyolysis.

CONCLUSIONS

Bystanders provide CPR for patients who are not in cardiac arrest at a relatively low frequency. Short-duration bystander CPR caused injury in less than 2% of victims. Our results suggest that the benefits of bystander CPR for adults who suddenly collapse outweigh the risk of injury for those not in cardiac arrest.

Mechanical versus manual chest compressions for cardiac arrest

BACKGROUND

Mechanical chest compression devices have been proposed to improve the effectiveness of cardiopulmonary resuscitation (CPR).

OBJECTIVES

To assess the effectiveness of mechanical chest compressions versus standard manual chest compressions with respect to neurologically intact survival in patients who suffer cardiac arrest.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Studies (CENTRAL) on The Cochrane Library, MEDLINE, EMBASE, Science Citation abstracts, Biotechnology and Bioengineering abstracts and Clinicaltrials.gov in November 2009. No language restrictions were applied. Experts in the field of mechanical chest compression devices and manufacturers were contacted.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), cluster RCTs and quasi-randomised studies comparing mechanical chest compressions to manual chest compressions during CPR for patients with atraumatic cardiac arrest.

DATA COLLECTION AND ANALYSIS

Two authors (SCB and LJM) abstracted data independently. Disagreement between reviewers was resolved by consensus and a third author (BB) if consensus could not be reached. The methodologies of selected studies were evaluated for risk of bias by a single author (SCB). The primary outcome was survival to hospital discharge with good neurologic outcome. We used the DerSimonian & Laird method (random-effects model) to provide a pooled estimate for relative risk with 95% confidence intervals.

MAIN RESULTS

Four trials, including data from 868 patients, were included in the review. The overall quality of included studies was poor and significant clinical heterogeneity was observed. Only one study (N = 767) reported survival to hospital discharge with good neurologic function (as defined as a Cerebral Performance Category score of 1 or 2), demonstrating reduced survival with mechanical chest compressions when compared with manual chest compressions (RR 0.41 (95% CI 0.21- 0.79). Data from other studies included in this review were used to calculate relative risks for having a return of spontaneous circulation (2 studies, N = 51, pooled RR 2.81, 95% CI 0.96 to 8.22) and survival to hospital admission (1 study, N = 17, RR 4.13, 95% CI 0.19 to 88.71) in patients who received mechanical chest compressions versus those who received manual chest compressions.

AUTHORS' CONCLUSIONS

There is insufficient evidence from human RCTs to conclude that mechanical chest compressions during cardiopulmonary resuscitation for cardiac arrest is associated with benefit or harm. Widespread use of mechanical devices for chest compressions during cardiac is not supported by this review. More RCTs that measure and account for CPR process in both arms are needed to clarify the potential benefit from this intervention.

Effect of defibrillation energy dose during in-hospital pediatric cardiac arrest

OBJECTIVE

To examine the effectiveness of initial defibrillation attempts. We hypothesized that (1) an initial shock dose of 2 ± 10 J/kg would be less effective for terminating fibrillation than suggested in published historical data and (2) a 4 J/kg shock dose would be more effective.

PATIENTS AND METHODS

This was a National Registry of Cardiopulmonary Resuscitation prospective, multisite, observational study of in-hospital pediatric (aged ≤18 years) ventricular fibrillation or pulseless ventricular tachycardia cardiac arrests from 2000-2008. Termination of ventricular fibrillation or pulseless ventricular tachycardia and event survival after initial shocks of 2 J/kg were compared with historic controls and a 4 J/kg shock dose.

RESULTS

Of 266 children with 285 events, 173 of 285 (61%) survived the event and 61 of 266 (23%) survived to discharge. Termination of fibrillation after initial shock was achieved for 152 of 285 (53%) events. Termination of fibrillation with 2 ± 10 J/kg was much less frequent than that seen among historic control subjects (56% vs 91%; P < .001), but not different than 4 J/kg. Compared with 2 J/kg, an initial shock dose of 4 J/kg was associated with lower rates of return of spontaneous circulation (odds ratio: 0.41 [95% confidence interval: 0.21-0.81]) and event survival (odds ratio: 0.42 [95% confidence interval: 0.18-0.98]).

CONCLUSIONS

The currently recommended 2 J/kg initial shock dose for in-hospital cardiac arrest was substantially less effective than previously published. A higher initial shock dose (4 J/kg) was not associated with superior termination of ventricular fibrillation or pulseless ventricular tachycardia or improved survival rates. The optimal pediatric defibrillation dose remains unknown.

Comparison of Supreme(®) and Soft Seal(®) laryngeal masks for airway management during cardiopulmonary resuscitation in novice doctors: a manikin study

PURPOSE

In the 2005 American Heart Association (AHA) guidelines, the laryngeal mask (LMA) was proposed as an alternative to tracheal intubation for cardiopulmonary resuscitation (CPR). We compared the utility of a newly developed LMA, the Supreme(®) (Supreme), with a conventional LMA, the Soft Seal(®) (Soft Seal).

METHODS

A total of 19 novice doctors in our anesthesia department performed insertion of the Supreme or Soft Seal on a manikin with or without chest compression. Insertion time and number of attempts for successful ventilation were measured. After successful ventilation, the amount of air entering the stomach and maximum ventilation pressure were measured. The subjective difficulty of using the devices was also measured.

RESULTS

The ventilation success rate of first insertion did not differ between the Supreme and Soft Seal without chest compression. However, the success rate was significantly lower with the Soft Seal than the Supreme during chest compression. Insertion time was lengthened by chest compression with the Soft Seal, but not with the Supreme. Maximum ventilation pressure was higher with the Supreme than the Soft Seal. The amount of air entering the stomach was significantly lower with the Supreme than the Soft Seal. The Supreme also scored better than the Soft Seal on a visual analog scale of subjective difficulty in insertion.

CONCLUSIONS

The Supreme is an effective device for airway management during chest compression.

Automated external defibrillators and survival after in-hospital cardiac arrest

CONTEXT

Automated external defibrillators (AEDs) improve survival from out-of-hospital cardiac arrests, but data on their effectiveness in hospitalized patients are limited.

OBJECTIVE

To evaluate the association between AED use and survival for in-hospital cardiac arrest.

DESIGN, SETTING, AND PATIENTS

Cohort study of 11,695 hospitalized patients with cardiac arrests between January 1, 2000, and August 26, 2008, at 204 US hospitals following the introduction of AEDs on general hospital wards.

MAIN OUTCOME MEASURE

Survival to hospital discharge by AED use, using multivariable hierarchical regression analyses to adjust for patient factors and hospital site.

RESULTS

Of 11,695 patients, 9616 (82.2%) had nonshockable rhythms (asystole and pulseless electrical activity) and 2079 (17.8%) had shockable rhythms (ventricular fibrillation and pulseless ventricular tachycardia). AEDs were used in 4515 patients (38.6%). Overall, 2117 patients (18.1%) survived to hospital discharge. Within the entire study population, AED use was associated with a lower rate of survival after in-hospital cardiac arrest compared with no AED use (16.3% vs 19.3%; adjusted rate ratio [RR], 0.85; 95% confidence interval [CI], 0.78-0.92; P < .001). Among cardiac arrests due to nonshockable rhythms, AED use was associated with lower survival (10.4% vs 15.4%; adjusted RR, 0.74; 95% CI, 0.65-0.83; P < .001). In contrast, for cardiac arrests due to shockable rhythms, AED use was not associated with survival (38.4% vs 39.8%; adjusted RR, 1.00; 95% CI, 0.88-1.13; P = .99). These patterns were consistently observed in both monitored and nonmonitored hospital units where AEDs were used, after matching patients to the individual units in each hospital where the cardiac arrest occurred, and with a propensity score analysis.

CONCLUSION

Among hospitalized patients with cardiac arrest, use of AEDs was not associated with improved survival.

Chest-compression-only versus standard cardiopulmonary resuscitation: a meta-analysis

BACKGROUND

In out-of-hospital cardiac arrest, dispatcher-assisted chest-compression-only bystander CPR might be superior to standard bystander CPR (chest compression plus rescue ventilation), but trial findings have not shown significantly improved outcomes. We aimed to establish the association of chest-compression-only CPR with survival in patients with out-of-hospital cardiac arrest.

METHODS

Medline and Embase were systematically reviewed for studies published between January, 1985, and August, 2010, in which chest-compression-only bystander CPR was compared with standard bystander CPR for adult patients with out-of-hospital cardiac arrest. In the primary meta-analysis, we included trials in which patients were randomly allocated to receive one of the two CPR techniques, according to dispatcher instructions; and in the secondary meta-analysis, we included observational cohort studies of chest-compression-only CPR. All studies had to supply survival data. The primary outcome was survival to hospital discharge. A fixed-effects model was used for both meta-analyses because of an absence of heterogeneity among the studies (I(2)=0%).

FINDINGS

In the primary meta-analysis, pooled data from three randomised trials showed that chest-compression-only CPR was associated with improved chance of survival compared with standard CPR (14% [211/1500] vs 12% [178/1531]; risk ratio 1·22, 95% CI 1·01-1·46). The absolute increase in survival was 2·4% (95% CI 0·1-4·9), and the number needed to treat was 41 (95% CI 20-1250). In the secondary meta-analysis of seven observational cohort studies, no difference was recorded between the two CPR techniques (8% [223/2731] vs 8% [863/11 152]; risk ratio 0·96, 95% CI 0·83-1·11).

INTERPRETATION

For adults with out-of-hospital cardiac arrest, instructions to bystanders from emergency medical services dispatch should focus on chest-compression-only CPR.

FUNDING

US National Institutes of Health and American Heart Association.

Effect of continuous compressions and 30:2 cardiopulmonary resuscitation on global ventilation/perfusion values during resuscitation in a porcine model

OBJECTIVE

Rescue ventilations during bystander resuscitation, although previously considered essential, interrupt the continuity of chest compressions and might have deleterious effects in basic life support. This study was undertaken to analyze the global ventilation/perfusion values of continuous compressions and 30:2 cardiopulmonary resuscitation to determine the effectiveness for each approach in a porcine model of prolonged bystander cardiopulmonary resuscitation for ventricular fibrillation.

DESIGN

Prospective, randomized animal study.

SETTING

A university animal research laboratory.

SUBJECTS

Twenty-four male domestic pigs (n = 12/group) weighing 30 ± 2 kg.

INTERVENTIONS

All animals had ventricular fibrillation induced by programmed electrical stimulation instruments and were randomized into two groups. Continuous compressions or 30:2 compression/rescue ventilation cardiopulmonary resuscitation was performed in each group.

MEASUREMENTS AND MAIN RESULTS

Continuous respiratory variables, hemodynamic parameters, and blood gas analysis outcomes were recorded, and global ventilation/perfusion values were calculated. Alveolar minute volume and global ventilation/perfusion values decreased progressively after ventricular fibrillation, but cardiac output was stable. The global ventilation/perfusion value was higher in the ventilation cardiopulmonary resuscitation group than that in the continuous compression group (p < .0001) and was higher than normal. Coronary perfusion pressure was progressively decreased after 6 mins of cardiopulmonary resuscitation and greatly fluctuated in the ventilation cardiopulmonary resuscitation group. Coronary perfusion pressure was higher in the continuous compression group than that in the ventilation cardiopulmonary resuscitation group after 9 mins of cardiopulmonary resuscitation (p < .05). Values for pH and Pao2 progressively decreased, but there were no significant differences between the two groups, except for pH at 12 mins of cardiopulmonary resuscitation and Paco2 after 3 mins of cardiopulmonary resuscitation.

CONCLUSIONS

In the first 12 mins of cardiopulmonary resuscitation, continuous compressions could maintain relatively better coronary perfusion pressure, Pao2, and global ventilation/perfusion values than 30:2 cardiopulmonary resuscitation. Therefore, rescue ventilation during 12 mins of simulated bystander cardiopulmonary resuscitation did not improve hemodynamics or outcomes compared with compression-only cardiopulmonary resuscitation.

Simulation in resuscitation teaching and training, an evidence based practice review

In the management of a patient in cardiac arrest, it is sometimes the least experienced provider giving chest compressions, intubating the patient, and running the code during the most crucial moment in that patient's life. Traditional methods of educating residents and medical students using lectures and bedside teaching are no longer sufficient. Today's generation of trainees grew up in a multimedia environment, learning on the electronic method of learning (online, internet) instead of reading books. It is unreasonable to expect the educational model developed 50 years ago to be able to adequately train the medical students and residents of today. One area that is difficult to teach is the diagnosis and management of the critically ill patient, specifically who require resuscitation for cardiac emergencies and cardiac arrest. Patient simulation has emerged as an educational tool that allows the learner to practice patient care, away from the bedside, in a controlled and safe environment, giving the learner the opportunity to practice the educational principles of deliberate practice and self-refection. We performed a qualitative literature review of the uses of simulators in resuscitation training with a focus on their current and potential applications in cardiac arrest and emergencies.

A comparison between over-the-head and standard cardiopulmonary resuscitation performed by two rescuers: a simulation study

BACKGROUND

In cardiopulmonary resuscitation (CPR) of a patient with an unsecured airway performed by two health care professionals, two methods are possible: 1) Standard CPR according to the guidelines, with one rescuer performing chest compressions from the side and the other rescuer performing ventilations from over the head of the patient. Additional tasks (like attaching the electrocardiogram and defibrillator) must be performed by the second rescuer during the time between ventilations. 2) Over-the-head CPR, with one rescuer performing chest compressions and ventilations from over the head and the other rescuer performing additional tasks.

OBJECTIVES

The aim of this study was to compare the quality of CPR achieved by the two methods.

METHODS

After a standardized theoretical introduction and practical training, 106 medical students with limited knowledge and training in CPR participated in this randomized crossover study. Students performed a 2-min CPR test of standard CPR in both positions and over-the-head CPR alone on a manikin.

RESULTS

Standard CPR led to a significantly shorter hands-off-time over a 2-min interval than over-the-head CPR (median 25 s [interquartile range (IQR) 22-26 s] vs. 38 s [IQR 36-43 s], respectively, p < 0.001), and significantly more chest compressions (167 [IQR 158-176] vs. 142 [IQR 132-150], respectively, p < 0.001), more correct chest compressions (72 [IQR 11-136] vs. 45 [IQR 13-88], respectively, p = 0.004), inflations (10 [IQR 10-10] vs. 8 [IQR 8-8], respectively, p < 0.001), and correct inflations (5 [IQR 2-7] vs. 3 [IQR 1-4], respectively, p < 0.001).

CONCLUSIONS

In the case of a two-professional-rescuer CPR scenario, standard CPR enables a quantitatively better resuscitation than over-the-head CPR.

Effectiveness of mouth-to-mouth ventilation after video self-instruction training in laypersons

BACKGROUND

Mouth-to-mouth ventilation is a skill taught in cardiopulmonary resuscitation (CPR) training for laypersons. However, its effectiveness is questioned. Our aim was to determine the effectiveness of mouth-to-mouth ventilation training using a self-instruction CPR training video for laypersons.

METHODS

Video-self-instruction CPR training was conducted with CPR Anytime (American Heart Association [AHA] & Laerdal Corporation) for laypersons who had not received CPR training during the recent 5 years. Immediately before, immediately after, and 8 weeks after the CPR training, an AHA basic life support instructor carried out a skill performance test using a standardized checklist. Also, 8 weeks after the training, a skill test concerning chest compression and mouth-to-mouth ventilation was conducted using a trained reporter.

RESULTS

Cardiopulmonary resuscitation training of 84 laypersons was conducted. The mean performance score (from 0 to 2) for mouth-to-mouth ventilation was 0.24 right before the training, 1.58 right after the training, and 0.95 eight weeks after the training. The mean performance scores for chest compression were 0.13, 1.79, and 1.40, right before, right after, and 8 weeks after the CPR training, respectively. The rates of successful mouth-to-mouth ventilation and compression were 11.9%, and 39.1%, respectively.

CONCLUSIONS

The effectiveness and short-term retention rate of mouth-to-mouth ventilation after video self-instruction CPR training in laypersons was significantly lower than for chest compressions.

Compression-only CPR or standard CPR in out-of-hospital cardiac arrest

BACKGROUND

Emergency medical dispatchers give instructions on how to perform cardiopulmonary resuscitation (CPR) over the telephone to callers requesting help for a patient with suspected cardiac arrest, before the arrival of emergency medical services (EMS) personnel. A previous study indicated that instructions to perform CPR consisting of only chest compression result in a treatment efficacy that is similar or even superior to that associated with instructions given to perform standard CPR, which consists of both compression and ventilation. That study, however, was not powered to assess a possible difference in survival. The aim of this prospective, randomized study was to evaluate the possible superiority of compression-only CPR over standard CPR with respect to survival.

METHODS

Patients with suspected, witnessed, out-of-hospital cardiac arrest were randomly assigned to undergo either compression-only CPR or standard CPR. The primary end point was 30-day survival.

RESULTS

Data for the primary analysis were collected from February 2005 through January 2009 for a total of 1276 patients. Of these, 620 patients had been assigned to receive compression-only CPR and 656 patients had been assigned to receive standard CPR. The rate of 30-day survival was similar in the two groups: 8.7% (54 of 620 patients) in the group receiving compression-only CPR and 7.0% (46 of 656 patients) in the group receiving standard CPR (absolute difference for compression-only vs. standard CPR, 1.7 percentage points; 95% confidence interval, -1.2 to 4.6; P=0.29).

CONCLUSIONS

This prospective, randomized study showed no significant difference with respect to survival at 30 days between instructions given by an emergency medical dispatcher, before the arrival of EMS personnel, for compression-only CPR and instructions for standard CPR in patients with suspected, witnessed, out-of-hospital cardiac arrest. (Funded by the Swedish Heart–Lung Foundation and others; Karolinska Clinical Trial Registration number, CT20080012.)

CPR with chest compression alone or with rescue breathing

BACKGROUND

The role of rescue breathing in cardiopulmonary resuscitation (CPR) performed by a layperson is uncertain. We hypothesized that the dispatcher instructions to bystanders to provide chest compression alone would result in improved survival as compared with instructions to provide chest compression plus rescue breathing.

METHODS

We conducted a multicenter, randomized trial of dispatcher instructions to bystanders for performing CPR. The patients were persons 18 years of age or older with out-of-hospital cardiac arrest for whom dispatchers initiated CPR instruction to bystanders. Patients were randomly assigned to receive chest compression alone or chest compression plus rescue breathing. The primary outcome was survival to hospital discharge. Secondary outcomes included a favorable neurologic outcome at discharge.

RESULTS

Of the 1941 patients who met the inclusion criteria, 981 were randomly assigned to receive chest compression alone and 960 to receive chest compression plus rescue breathing. We observed no significant difference between the two groups in the proportion of patients who survived to hospital discharge (12.5% with chest compression alone and 11.0% with chest compression plus rescue breathing, P=0.31) or in the proportion who survived with a favorable neurologic outcome in the two sites that assessed this secondary outcome (14.4% and 11.5%, respectively; P=0.13). Prespecified subgroup analyses showed a trend toward a higher proportion of patients surviving to hospital discharge with chest compression alone as compared with chest compression plus rescue breathing for patients with a cardiac cause of arrest (15.5% vs. 12.3%, P=0.09) and for those with shockable rhythms (31.9% vs. 25.7%, P=0.09).

CONCLUSIONS

Dispatcher instruction consisting of chest compression alone did not increase the survival rate overall, although there was a trend toward better outcomes in key clinical subgroups. The results support a strategy for CPR performed by laypersons that emphasizes chest compression and minimizes the role of rescue breathing. (Funded in part by the Laerdal Foundation for Acute Medicine and the Medic One Foundation; ClinicalTrials.gov number, NCT00219687.)

Extended series of cardiac compressions during CPR in a swine model of perinatal asphyxia

BACKGROUND

The rationale for a compression to ventilation ratio of 3:1 in neonates with primary hypoxic, hypercapnic cardiac arrest is to emphasize the importance of ventilation; however, there are no published studies testing this approach against alternative methods. An extended series of cardiac compressions offers the theoretical advantage of improving coronary perfusion pressures and hence, we aimed to explore the impact of compression cycles of two different durations.

MATERIALS AND METHODS

Newborn swine (n = 32, age 12-36 h, weight 2.0-2.7 kg) were progressively asphyxiated until asystole occurred. Animals were randomized to receive compressions:ventilations 3:1 (n=16) or 9:3 (n=16). Return of spontaneous circulation (ROSC) was defined as a heart rate ≥ 100 beats min⁻¹.

RESULTS

All animals except one in the 9:3 group achieved ROSC. One animal in the 3:1 group suffered bradycardia at baseline, and was excluded, leaving us with 15 animals in each group surviving to completion of protocol. Time to ROSC (median and interquartile range) was 150 s (115-180) vs. 148 s (116-195) for 3:1 and 9:3, respectively (P = 0.74). There were no differences in diastolic blood pressure during compression cycles or in markers of hypoxia and inflammation. The temporal changes in mean arterial blood pressure, heart rate, arterial blood gas parameters, and systemic and regional oxygen saturation were comparable between groups.

CONCLUSION

Neonatal pigs with asphyxia-induced cardiac arrest did not respond to a compression:ventilation ratio of 9:3 better than to 3:1. Future research should address if alternative compression:ventilation ratios offer advantages over the current gold standard of 3:1.

An organized system of emergency care for patients with myocardial infarction: a reality?

An organized system of emergency care is an essential requirement for the modern treatment of ST-elevation acute myocardial infarction. There is a strong need to deliver reperfusion therapy as soon as possible, with primary percutaneous coronary intervention being the preferred option if performed in a timely manner and thrombolytic therapy, particularly in the prehospital setting, being a good alternative if the primary percutaneous coronary intervention-related delay exceeds the equipoise. In this situation, emergency medical services have a primary role in rescuing patients from cardiac arrest, performing prehospital diagnosis, triage and treatment and safely transporting them to the most appropriate cardiological center, including interhospital transfer. A complete reorganization of the healthcare systems in different countries is frequently needed to build an ST-elevation acute myocardial infarction system of care, focusing on fast transport, use of telemedicine and diversion protocols to skip the unsuited centers.

Electrocardiographic analysis during uninterrupted cardiopulmonary resuscitation

OBJECTIVE

Prior studies have shown that interruptions of chest compressions could result in high failure rates of resuscitation. Chest compression artifacts force the interruption of compressions before electrocardiographic rhythm analysis. It was the goal of this study to evaluate the accuracy of an automated electrocardiographic rhythm analysis algorithm designed to attenuate compression-induced artifact and minimize uninterrupted chest compressions.

DESIGN

Retrospective diagnostic analysis.

SETTING

Out-of-hospital cardiopulmonary resuscitation.

SUBJECTS

Eight hundred thirty-two patients.

INTERVENTIONS

Patients were treated with defibrillation and cardiopulmonary resuscitation. Continuous data were recorded using automated external defibrillators with concurrent measurement of electrocardiographic and sternal motion during chest compressions.

MEASUREMENTS AND RESULTS

Human electrocardiographics recorded by automated external defibrillators were annotated and randomly selected to build distinct training and testing databases. The artifact reduction and tolerant filter was applied to the electrocardiographic signal. The algorithm was optimized with the training database (sensitivity, 93.9%; specificity, 91.2%) and tested with the testing database (sensitivity, 92.1%; specificity, 90.5%). Average attenuation of compression-induced artifact was more than 35 dB.

CONCLUSIONS

Shockable ventricular arrhythmias can be differentiated from electrocardiographic rhythms not requiring defibrillation in the presence of chest compression-induced artifact with sensitivity and specificity above 90%. With the artifact reduction and tolerant filter, it is possible to effectively eliminate pre- and postshock compression pauses.

Diagnostic performance of a new multifunctional electrocardiograph during uninterrupted chest compressions in cardiac arrest patients

BACKGROUND

External chest compression is considered to play a significant role in cardiopulmonary resuscitation (CPR), but during a rhythm check, chest compressions must be discontinued to avoid artifacts. A new multifunctional electrocardiograph (ECG; Radarcirc) has been developed for use in clinical settings.

METHODS AND RESULTS

The performance of the Radarcirc and conventional ECG (CoECG) during CPR was compared in a single-center, non-randomized, sequential self-controlled study. CPR was performed on 41 out-of-hospital cardiac arrest patients. Cardiac rhythm with and without chest compressions during a rhythm check was measured using leads I and II. When the rhythm changed during CPR, it was measured as another waveform. Fifty ECG recordings were obtained, of which 27 were asystole, 18 pulseless electrical activity, and 5 ventricular fibrillation (VF). The area under the receiver-operating characteristic curve (AUC) for VF was 0.448 (95% confidence interval (CI) 0.274-0.622) for lead II of the CoECG, and 0.797 (95%CI 0.684-0.910) for lead II of the Radarcirc. The AUC for VF was 0.422 (95%CI 0.219-0.626) for lead I of the CoECG, and 0.987 (95%CI 0.975-1.00) for lead I of the Radarcirc.

CONCLUSIONS

Diagnoses based on the data from Radarcirc were more accurate in predicting rhythm during chest compressions than those based on data from the CoECG.

Validation of the Pentax-AWS Airwayscope utility as an intubation device during cardiopulmonary resuscitation on the ground

PURPOSE

The 2005 American Heart Association guidelines for cardiopulmonary resuscitation emphasize that all rescuers should minimize interruption of chest compressions even for endotracheal intubation. We previously reported that the utility of the Pentax-AWS Airwayscope (AWS) was superior to that of the Macintosh laryngoscope (McL) for securing airways during chest compression in "on the bed" simulated circumstances. However, because most cardiopulmonary arrest happens "on the ground" in the real world, we compared the utility of the McL and the AWS during chest compression on the ground and on the bed.

METHODS

Fourteen doctors training in the anesthesia department performed tracheal intubation on a manikin with the McL and the AWS in simulations "on the bed" and "on the ground".

RESULTS

In the McL trial, 6 participants failed on the bed, and 10 of them also failed on the ground during chest compression. In the AWS trial, all participants successfully secured the airway regardless of chest compression both on the bed and on the ground. With the AWS, intubation time was not lengthened because of chest compression either on the bed or on the ground. The AWS scored better than the McL on the visual analog scale in laryngoscopy and tube passage of the glottis both on the bed and on the ground.

CONCLUSION

We conclude that the AWS is an effective device for endotracheal intubation during chest compression not only on the bed but also on the ground.

Focused examination of cerebral blood flow in peri-resuscitation: a new advanced life support compliant concept—an extension of the focused echocardiography evaluation in life support examination

Aim

To introduce a new concept of the extension of focused echocardiography evaluation in life support (FEEL) with advanced life support (ALS)-compliant duplex sonography of the extracranial internal carotid artery (ICA) blood flow velocity for monitoring of cerebral blood circulation during peri-resuscitation.

Concept and results

With respect to pulseless electrical activity states, the question of adequate cerebral blood flow (CBF) cannot be answered by echocardiography alone. Pulse checks are unreliable. To build up a concept for assessing CBF, we analyzed duplex sonography workflow in three adults on the intensive care unit (postoperative, cardiogenic shock, cardiac standstill), and in simulated procedures. We decided to use duplex flow velocity of the ICA, for it is an accepted measurement for estimating CBF and it seems to be easy to obtain a window and interpretation during peri-resuscitation. The presence of an arterial blood flow pattern and an end-diastolic flow velocity of more than 20 cm/s, arbitrarily set, is considered to indicate sufficient CBF. The method of ICA flow velocity analysis during peri-resuscitation was tentatively added to the FEEL concept and is described with algorithm, workflow and three cases. This method may give an assist to answer the question, if CBF is sufficient, when myocardial wall motion is detectable in peri-resuscitation care.

Conclusion

This new concept of an ALS-conformed analysis of ICA blood flow velocity by duplex sonography may provide a simple, fast applicable and inexpensive method to qualitatively assess CBF in the peri-resuscitation setting.

The optimal phasic relationship between synchronized shock and mechanical chest compressions

OBJECTIVE

Pauses for shock delivery in chest compressions are detrimental to the success of resuscitation and may be eliminated with the use of mechanical chest compressors. However, the optimal phasic relationship between mechanical chest compression and defibrillation is still unknown. We therefore undertook a study to assess the effects of timing of defibrillation in the mechanical chest compression cycle on the defibrillation threshold (DFT) using a porcine model of cardiac arrest.

METHODS

Ventricular fibrillation was electrically induced and untreated for 10s in 8 domestic pigs weighing between 26 and 30 kg. Mechanical chest compression was then continuously performed for 25s, followed by a biphasic electrical shock which was delivered to the animal at 6 randomized coupling phases, including a control phase, with a pre-determined energy setting. The control phase was chosen at a constant 2s following discontinued chest compression. A novel grouped up-and-down DFT testing protocol was used to compare the success rate at different coupling phases. After a recovery interval of 4 min, the testing sequence was repeated, resulting in a total of 60 test shocks delivered to each animal.

RESULTS

No difference between the delivered shock energy, voltage and current were observed among the 6 study phases. The defibrillation success rate, however, was significantly higher when shocks were delivered in the upstroke phase of mechanical chest compression.

CONCLUSION

Defibrillation efficacy is maximal when electrical shock is delivered in the upstroke phase of mechanical chest compression.