Why Should We Care About CARE-HF?

Previous trials of cardiac resynchronization therapy (CRT) have suggested that this therapy can significantly improve functional class and exercise capacity during short-term follow-up. The impact of this therapy on morbidity and mortality has only recently been reported. The Cardiac Resynchronization-Heart Failure (CARE-HF) study has definitively shown that CRT significantly reduces mortality (36%, p < 0.002) in patients with NYHA functional class III and IV heart failure and ventricular dyssynchrony. This study also shows that CRT reverses ventricular remodeling and improves myocardial performance progressively for at least 18 months. In heart failure patients, the CARE-HF and Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) (the earlier major morbidity/mortality trial) studies together show the unequivocal benefit for CRT therapy and CRT therapy with back-up defibrillation to significantly reduce mortality and hospitalization compared with optimal medical therapy. Both studies suggest the benefit of adding the implantable cardiac defibrillator to CRT devices, as over one-third of deaths in the CRT-pacemaker arm of both the COMPANION and CARE-HF studies were sudden.

Demystifying biphasic defibrillation

This technology is making defibrillators less likely to injure patients. Here's what you need to know.

[Resuscitation in ventricular fibrillation: what is essential?]

Prognosis of prehospital cardiac arrest due to ventricular fibrillation is dependent on the first minutes, as survival decreases by 10% for each minute by which resuscitation attempts are delayed. Thus, early defibrillation plays a key role in improving outcome of cardiac arrest victims. The effectiveness of automated external defibrillators (AEDs) in this setting has been proven by several clinical trials. There remains controversy with regard to using AEDs in the in-hospital setting, as well as the approach of "public access" defibrillation. Whereas the use of intravenous antiarrhythmic drugs, particularly amiodarone, remains controversial, new data support the use of vasopressine instead of epinephrine as vasopressor drug in cardiac arrest patients. The present review aims to focus on the above mentioned aspects as well as on the changes to the present ILCOR guidelines which have led to modification of the resuscitation guidelines of the European Resuscitation Council (ERC).

A study comparing the usability of fully automatic versus semi-automatic defibrillation by untrained nursing students

INTRODUCTION

Current international guidelines prefer the use of semi-automatic external defibrillators (SAEDs) over fully automatic external defibrillators (FAEDs). However, there is a lack of evidence supporting this recommendation. We conducted a study of usability with nursing students comparing the FAED version against the SAED version of the Lifepak CR Plus AED (Medtronic, Redmond, USA). We hypothesized that FAED use would limit the number of operator-device interactions, thereby increasing compliance by the rescuer, safety and speed.

METHODS

Sixty-two untrained first year nursing students were randomized to use the FAED or the SAED in a simulated cardiac arrest scenario. During analysis and delivery of three shocks, the AED guided the user with six voice prompts per shock (18 voice prompts per student). Their performance with regard to efficacy and safety was assessed using video recording.

RESULTS

All rescuers except for two were able to attach electrodes and deliver a series of three shocks. During rhythm analysis by the device, FAED users made 30/372 (8%) errors against 62/360 (17%) errors for SAED users (P < 0.001). During shock delivery, FAED users made 0/186 errors against 12/180 (7%) for SAED users (P < 0.001). FAED use eliminated long time intervals between the first to the third shock (range 47-49s for FAED versus 41-90s for SAED).

CONCLUSION

Despite a lack of BLS skills and AED training, the majority of students demonstrated safe and effective use of the AED. The use of the FAED version of the CR Plus resulted in increased compliance with the protocol and reduced variability in time to deliver three shocks. Further research is needed to confirm these findings in other groups of first responders.

One conversion of ventricular fibrillation is adequate for implantable cardioverter-defibrillator implant: An analysis from the Low Energy Safety Study (LESS)

OBJECTIVES

The purpose of this study was to analyze defibrillation conversion data from the Low Energy Safety Study (LESS) to determine how implant criteria that use fewer inductions of ventricular fibrillation (VF) correlate with outcome and, in particular, to assess the reliability of using a single VF induction and test shock at 14 J.

BACKGROUND

A safety margin of 10 J has become standard for implantation of an implantable cardioverter-defibrillator (ICD), but the specifics and rigor of the implant test sequence are not standardized.

METHODS

In LESS, 611 ICD recipients completed a rigorous VF induction test scheme that began at 14 J and continued until the energy that succeeded three times without a failure was determined (DFT++). The data were analyzed to determine how well the outcome of the first 14-J shock and various other combinations of first and/or second shocks predicted a rigorous gold standard of DFT++ < or =21 J (i.e., three successes at < or =21 J).

RESULTS

The positive predictive accuracy for the 91% of patients in whom the first 14-J shock succeeded was virtually identical to the positive predictive accuracy for the commonly used criteria of two successes at < or =17 J (99.1% vs 99.0%, P = .69), and slightly higher than the positive predictive accuracy for two successes at < or =21 J (98.8%, P = .51). A single success at 17 J or 21 J had a somewhat lower positive predictive accuracy of 98.2% (P = .17). Eliminating VF induction testing would have resulted in a significantly lower positive predictive accuracy of 97.1% (P = .01).

CONCLUSIONS

A single conversion success at 14 J on the first VF induction provides similar positive predictive accuracy as two successes at 17 J or 21 J. Using this criterion, 91% of patients meet implant criteria with a single induction of ventricular fibrillation.

Adherence to guidelines when positioning the defibrillation electrodes

BACKGROUND

Placement of the defibrillation electrodes affects the transmyocardial current and thus the success of a defibrillation attempt. In the international guidelines 2000, the placement of the apical electrode was changed more laterally to the mid-axillary line. Finnish national guidelines, based on the international guidelines, were published in 2002.

OBJECTIVES

The purpose of this study was to determine to what extent health care professionals adhere to the new guidelines when positioning the electrodes.

METHODS

Professionals were recruited from emergency medical services, university hospitals and primary care. Not revealing the purpose of the test, participants were asked to place self-adhesive electrodes on a manikin as they would do in the resuscitation situation and to answer a questionnaire about resuscitation training and familiarity with the guidelines. The distance of electrodes from the recommended position was measured in horizontal and vertical planes.

RESULTS

One-hundred and thirty six professionals participated in the study, and only 25.4% (95% CI 18.5-32.9) of them placed both electrodes within 5 cm from the recommended position. The majority of the participants placed the apical electrode too anteriorly. Of the participants, 36.0% were not aware of the new guidelines. Awareness of the guidelines did not increase the accuracy in electrode placement.

CONCLUSIONS

The publication of the national evidence based resuscitation guidelines did not seem to have influenced the practice of placement of the defibrillation electrodes to any major extent. The correct placement of the electrodes needs be emphasized more in the resuscitation training.

Cardiac arrest care and emergency medical services in Canada

BACKGROUND

Heart disease is the primary cause of mortality in Canada and survival to hospital discharge from out-of-hospital cardiac arrest is low.

OBJECTIVE

To provide an overview of the outcomes for out-of-hospital cardiac arrest in Canada.

METHODS

A national, descriptive, Utstein-style analysis of cardiac arrest care and emergency medical services was conducted. Data were compiled from five sources: the City of Edmonton Emergency Response Department, the British Columbia Ambulance Service, the Nova Scotia Emergency Health Services, the Urgences-santé corporation of the Montreal Metropolitan region and the Ontario Prehospital Advanced Life Support (OPALS) Study database.

RESULTS

There were 5288 cardiac arrests from a range of small communities to large provincial cardiac arrest registries in 2002. They were men (62.6% to 70.1%) in their sixties and seventies, witnessed (35.2% to 55.0%), rarely receiving bystander cardiopulmonary resuscitation (CPR) (14.7% to 46.0%), often in asystole (35.7% to 51.3%), arresting at home (56.1%) and rarely surviving to hospital discharge (4.3% to 9.0%). Bystander CPR and early first responder defibrillation were significantly associated with increased survival. Cardiac arrest incidence rates per 100,000 varied between 53 and 59 among provinces and followed a downward trend.

CONCLUSIONS

The results of this study could be an important first step toward a national cardiac arrest registry comparing the impact of regional differences in patient and system characteristics. Many communities do not have accurate data on their performance with regards to the chain of survival, or need to significantly improve their capacity for providing citizen bystander CPR and rapid first responder defibrillation.

[Evaluation of BLS-D training in lay people]

BACKGROUND

The possibility of saving persons with sudden cardiac arrest (SCA) lowers of 10% every minute since the beginning of the event. The early defibrillation (within 4 min) of a person with SCA performed by first responders suitably trained increases the survival rate up to 50%. The basic aim is that early defibrillation is performed as soon as possible by the first responder.

METHODS

Within the Public Access Defibrillation (PAD) "Napoli Cuore" Project, 220 highway patrol agents of the Campania Region district were trained through theoretical and practical courses to acquire suitable psychomotor skills to perform the first aid. The learning evaluation was performed with a written exam and a practical test to assess how much every agent had learned about basic life support-defibrillation (BLS-D) schemes.

RESULTS

98.5% of the participants passed the exams and obtained the BLS-D rescuer license, and 15.5% of them obtained the highest score. The analysis of the report cards showed that most of the participants expressed an excellent opinion about this experience.

CONCLUSIONS

To implement a PAD project it is necessary to awaken all the structures involved in the campaign against SCA. Hence, it is important that all emergency specialists, public institutions and police departments work all together to make everyone feels safe.

Voraussetzungen zur Anwendung von automatischen externen Defibrillatoren in deutschen Krankenh�usern

With an incidence of 130,000 per year, sudden cardiac death is one of the most frequent causes of death in Germany. Each day 350 patients die from cardiac arrest. Survival depends essentially on the time delay before professional help arrives and sufficient resuscitation measures have been started. At present, survival of sudden cardiac death is reported to be in the range of 5-8%. In preclinical conditions, many studies have already shown a successful use of automated external defibrillators (AED) by first responders even if they are lay persons. Even in large hospitals with maximum care facilities, delays before beginning resuscitation measures can occur which results in a dramatic reduction of the survival rate. Therefore, it seems reasonable to use AED in large hospitals. For implementation, training programmes and a nationally standardized documentation of resuscitation events should be promoted.

Indications for an implantable cardioverter defibrillator (ICD)

Since the first clinical use of implantable defibrillator in human, the technology and the function of implantable cardioverter-defibrillator (ICD) have been much improved and now, ICD can be implanted within the chest wall. ICD is the most reliable therapy to prevent sudden cardiac death (SCD) in patients with documented VT/VF and the efficacy is most clear in patients with depressed heart function. It is now extended as a tool of the primary prevention of SCD in high risk patients after myocardial infarction. However, such beneficial effect is not applicable to DCM though patients might have depressed heart function. ICD is not free from procedure- or device-related problems which need to be resolved. From unknown causes, VT/VF might recur in an incessant form and an emergency admission is needed. Therefore, even during ICD therapy, patients often require antiarrhythmic drugs or catheter ablation.

Safety aspects for public access defibrillation using automated external defibrillators near high-voltage power lines

BACKGROUND

Automated external defibrillators (AEDs) must combine easy operability and high-quality diagnosis even under unfavorable conditions. This study determined the influence of electromagnetic interference caused by high-voltage power lines with 16.7-Hz alternating current on the quality of AEDs' rhythm analysis.

METHODS

Two AEDs frequently used in Austria were tested near high-voltage power lines (15 kV or 110 kV, alternating current with 16.7 Hz). The defibrillation electrodes were attached either to a proband with true sinus rhythm or to a resuscitation dummy with generated sinus rhythm, ventricular fibrillation, ventricular tachycardia or asystole.

RESULTS

Electromagnetic interference was much more prominent in a human's than in a dummy's electrocardiogram and depended on the position of the electrodes and cables in relation to the power line. Near high-voltage power lines the AEDs showed a significant operational fault. One AED interpreted the interference as a motion artifact, even when underlying rhythms were clearly detectable. The other AED interpreted 16.7-Hz oscillation as ventricular fibrillation with consequent shock advice when no underlying rhythm was detected.

CONCLUSION

The tested AEDs neither filter nor recognize a technical interference of 16.7 Hz caused by 15-kV power lines above railway tracks or 110-kV overland power lines, as run by railway companies in Austria, Germany, Norway, Sweden and Switzerland. These failures in AEDs' algorithms for rhythm analysis may cause substantial harm to patients undergoing public access defibrillation. The proper function of AEDs needs to be reconsidered to guarantee patients' safety near high-voltage power lines.

[A comparison of the two schemes of protection of the electrocardiograph against defibrillator impulse]

Two typical scheme of protection of the input cascade of the electrocardiograph against defibrillator impulses are under consideration. It is concluded that the conditions of check-up and testing as envisaged in State Standard R 50267.25 (MEK 601-2-25-93), is not in line with the real operation conditions, therefore, appropriate changes are suggested to be made in the above Standard. The offered scheme is shown to ensure a decrease of the electrodes' polarization potential by 100 times.

Vergleichende Untersuchungen zur Zuverlässigkeit automatisierter externer Defibrillatoren / Comparative Reliability Analysis of Automatic External Defibrillators

Automatic external defibrillators are gaining increasing acceptance. Last year 6000 devices were installed in Germany. Since the average user has only limited medical knowledge, high demands have to be made on the automatic ECG diagnosis (fibrillation detection). Within the framework of this study a fully automatic test system that permits an objective comparison of the performance of the various devices available on the market was constructed. Older devices in particular do not always meet the requirements defined by international standards with regard to sensitivity and specificity. In addition, company philosophy appears to differ in terms of the preferential emphasis on sensitivity or specificity. Purchasers of such devices need take these findings into consideration.

Sedation for cardioversion in the emergency department

STUDY OBJECTIVE

We compare effectiveness, adverse effects, and recovery times of propofol, etomidate, and midazolam (with and without flumazenil) for cardioversion in the emergency department (ED).

METHODS

Thirty-two hemodynamically stable adult patients undergoing cardioversion in the ED were randomly assigned to receive etomidate (n=9), propofol (n=9), midazolam (n=8), or midazolam followed by flumazenil (n=6). For all patients, we measured induction time, awakening time, total recuperation time, global time, and adverse effects. Arterial pressure, cardiac and respiratory rate, and peripheral oxygen saturation were monitored throughout the procedure. Descriptive and nonparametric tests were used.

RESULTS

Demographic data were similar in all groups. Deep sedation and successful cardioversion were achieved in all cases. Hemodynamic assessment at baseline, after induction, after cardioversion, and at recovery demonstrated no significant difference between the 4 groups. Induction time was short in all groups. Awakening time was longer in the midazolam group (median 21 minutes, range 1 to 42 minutes) compared with that of the other groups (etomidate group: median 9.5 minutes, range 5 to 11 minutes; propofol group: median 8 minutes, range 3 to 15 minutes; midazolam/flumazenil group: median 3 minutes, range 2 to 5 minutes), and the same occurred with total recuperation time (etomidate group: median 14 minutes, range 5 to 20 minutes; propofol group: median 10 minutes, range 5 to 15 minutes; midazolam group: median 45 minutes, range 20 to 60 minutes; midazolam/flumazenil group: median 5 minutes, range 2 to 90 minutes). All patients in the midazolam/flumazenil group but 1 became resedated after flumazenil was discontinued. Four patients who had received etomidate exhibited myoclonus, which was pronounced and seizure-like in 1 case.

CONCLUSION

Four sedative regimens (propofol, etomidate, midazolam, and midazolam/flumazenil) were uniformly effective in facilitating ED cardioversion in hemodynamically stable adults. Propofol was well tolerated and lacked the myoclonus, prolonged sedation, and resedation noted with the latter 3 respective groups. Larger studies are needed to generalize these conclusions.