Part 3: Defibrillation

ICU nurses' perceptions of potential constraints and anticipated support to practice defibrillation: a qualitative study

AIM

The study examines the experience of intensive care nurses in caring for patients in cardiac arrest, and their perceptions of introducing nurse-led defibrillation.

METHOD

This was a descriptive, exploratory and qualitative study at an intensive care unit (ICU) of an acute regional hospital in Hong Kong. Twelve registered nurses were purposefully selected for interview.

RESULTS

Although all the participants were trained in basic life support, only 50% were trained in advanced cardiac life support (ACLS), and those trained in ACLS described having limited opportunities to apply their defibrillation knowledge. Whilst participants believed that they were theoretically prepared to influence the patient's resuscitation outcomes, newly qualified nurses were reluctant to be accountable for defibrillation. In contrast, experienced nurses were more willing to perform nurse-led defibrillation. Support from management, cooperation between nurses and doctors, regular in-hospital 'real-drill' programmes, sponsorship for training, and the use of alternative defibrillation equipment should be considered to encourage nurse-led defibrillation in ICU settings.

CONCLUSION

Nurse-led defibrillation is an approach of delivering prompt care to critically ill patients, and a way ahead for intensive care nursing in Hong Kong. Emphasis on a consistent policy to promote nurse-led defibrillation practice is needed.

Occupational affiliation does not influence practical skills in cardiopulmonary resuscitation for in-hospital healthcare professionals

BACKGROUND

D-CPR (Defibrillator Cardiopulmonary Resuscitation) is a technique for optimal basic life support during cardiopulmonary resuscitation (CPR). Guidelines recommend that healthcare professionals can perform CPR with competence. How CPR training and provision is organized varies between hospitals, and it is our impression that in Sweden this has generally improved during the last 15-20 years. However, some hospitals still do not have any AED (Automated External Defibrillators). The aim was to investigate potential differences in practical skills between different healthcare professions before and after training in D-CPR.

METHODS

Seventy-four healthcare professionals were video recorded and evaluated for adherence to a modified Cardiff Score. A Laerdal Resusci Anne manikin in connection to PC Skill reporting System was used to evaluate CPR quality. A simulated CPR situation was accomplished during a 5-10 min scenario of ventricular fibrillation. Paired and unpaired statistical methods were used to examine differences within and between occupations with respect to the intervention.

RESULTS

There were no differences in skills among the different healthcare professions, except for compressions per minute. In total, the number of compression per minute and depth improved for all groups (P < 0.001). In total, 41% of the participants used AED before and 96% of the participants used AED after the intervention (P < 0.001). Before intervention, it took a median time of 120 seconds until the AED was used; after the intervention, it took 82 seconds.

CONCLUSION

Nearly all healthcare professionals learned to use the AED. There were no differences in CPR skill performances among the different healthcare professionals.

Transthoracic application of electrical cardiopulmonary resuscitation for treatment of cardiac arrest

OBJECTIVE

Observational studies have shown that muscular stimulation contracting the thoracic cage may produce coronary perfusion pressures equal to manual chest compressions. This study examined electrical cardiopulmonary resuscitation for coronary perfusion pressures during ventricular fibrillation in a porcine model of cardiac arrest.

DESIGN

Prospective randomized controlled study.

SETTING

University affiliated research institute.

SUBJECTS

Domestic male pigs.

INTERVENTIONS

In seven domestic male pigs (40 +/- 2 kg), ventricular fibrillation was induced electrically and untreated for 10 secs. For each ventricular fibrillation episode, one of 16 electrical cardiopulmonary resuscitation stimulation protocols (pulse trains) or manual chest compression was applied. Each compression protocol was applied for 20 secs, followed by a defibrillation shock. The experimental procedure was performed across one or more randomized complete blocks. The electrical cardiopulmonary resuscitation pulse trains were defined by four two-level factors: pulse width (0.15 and 7.5 msec), pulse period (15 and 30 msec), train width (50 and 200 msec), and train rate (60 or 120 compressions per min). Pulse trains comprised two groups, based on pulse width (skeletal-based, 0.15 msec; cardiac-based, 7.5 msec).

MEASUREMENTS AND MAIN RESULTS

Train width was the significant design parameter for producing efficacious levels of coronary perfusion pressures for the skeletal-based electrical cardiopulmonary resuscitation pulse trains (p = 0.02). Both train width and train rate were significant design parameters for producing efficacious levels of coronary perfusion pressures for the cardiac-based electrical cardiopulmonary resuscitation pulse trains (p < 0.001, p = 0.5, respectively). Optimal skeletal-based and cardiac-based electrical cardiopulmonary resuscitation pulse trains were significantly better than ventricular fibrillation (p = 0.01, p = 0.01, respectively) and equivalent to manual chest compression (p = 0.2, p = 0.7, respectively) for sufficient coronary perfusion pressure levels.

CONCLUSIONS

Optimal skeletal-based and cardiac-based electrical cardiopulmonary resuscitation pulse train parameters generated levels of coronary perfusion pressure significantly greater than ventricular fibrillation and comparable with manual chest compression over a short interval of untreated cardiac arrest.

Treating critical supraventricular and ventricular arrhythmias

Atrial fibrillation (AF), atrial flutter, AV-nodal reentry tachycardia with rapid ventricular response, atrial ectopic tachycardia and preexcitation syndromes combined with AF or ventricular tachyarrhythmias (VTA) are typical arrhythmias in intensive care patients (pts). Most frequently, the diagnosis of the underlying arrhythmia is possible from the physical examination (PE), the response to maneuvers or drugs and the 12-lead surface electrocardiogram. In unstable hemodynamics, immediate DC-cardioversion is indicated. Conversion of AF to sinus rhythm (SR) is possible using antiarrhythmic drugs. Amiodarone has a conversion rate in AF of up to 80%. Ibutilide represents a class III antiarrhythmic agent that has been reported to have conversion rates of 50-70%. Acute therapy of atrial flutter (Aflut) in intensive care pts depends on the clinical presentation. Atrial flutter can most often be successfully cardioverted to SR with DC-energies <50 joules. Ibutilide trials showed efficacy rates of 38-76% for conversion of Aflut to SR compared to conversion rates of 5-13% when intravenous flecainide, propafenone or verapamil was administered. In addition, high dose (2 mg) of ibutilide was more effective than sotalol (1.5 mg/kg) in conversion of Aflut to SR (70 versus 19%). Drugs like procainamide, sotalol, amiodarone or magnesium were recommended for treatment of VTA in intensive care pts. However, only amiodarone is today the drug of choice in VTA pts and also highly effective even in pts with defibrillation-resistant out-of-hospital cardiac arrest (CA). There is a general agreement that bystander first aid, defibrillation and advanced life support is essential for neurologic outcome in pts after cardiac arrest due to VTA. Public access defibrillation in the hands of trained laypersons seems to be an ideal approach in the treatment of ventricular fibrillation (VF). The use of automatic external defibrillators (AEDs) by basic life support ambulance providers or first responder (FR) in early defibrillation programs has been associated with a significant increase in survival rates (SRs). However, use of AEDs at home cannot be recommended.

The early minutes of in-hospital cardiac arrest: shock or CPR? A population based prospective study

Objectives

In the early minutes of cardiac arrest, timing of defibrillation and cardiopulmonary resuscitation during the basic life support phase (BLS CPR) is debated. Aims of this study were to provide in-hospital incidence and outcome data, and to investigate the relation between outcome and time from collapse to defibrillation, time to BLS CPR, and CPR quality.

Methods

Resuscitation attempts during a 3-year period at St. Olav's University Hospital (960 beds) were prospectively registered. The times between collapse and initiation of BLS CPR, and defibrillation were determined. CPR quality was assessed by the resuscitation team. The relation between these variables and outcome (short term survival and discharge) was explored using non-parametric correlation and logistic regression.

Results

CPR was started in a total of 223 arrests, an incidence of 77 episodes per 1000 beds per year. Return of spontaneous circulation occurred in 40%, and 29 patients (13%) survived to discharge. Median time from collapse to BLS CPR was 1 minute; CPR was judged to be of good quality in half of the episodes. CPR during the first 3 minutes in ventricular fibrillation (VF/VT) was negatively associated with survival, but later proved beneficial. For patients with non-shockable rhythms, we found no association between outcome and time to BLS or CPR quality.

Conclusion

Our findings indicate that defibrillation should have priority during the first 3 minutes of VF/VT. Later, patients benefit from CPR in conjunction with defibrillation. Patients presenting with non-shockable rhythms have a grave prognosis, and the outcome was not associated with time to BLS or CPR quality.

Monitoring the quality of cardiopulmonary resuscitation

PURPOSE OF REVIEW

Numerous recent reports have described limitations in the quality of cardiopulmonary resuscitation. Thus, there has been increasing interest in the techniques available to monitor quality. This review focuses on the major publications since the review published by the International Liaison Committee on Resuscitation in 2005. Some key articles published prior to this time period have also been included.

RECENT FINDINGS

A number of devices can monitor various components of the quality of cardiopulmonary resuscitation. End-tidal CO2 measurement assists in confirming placement of endotracheal tubes, correlates with cardiac output and detects the return of spontaneous circulation. Turbine flow-meters monitor respiratory rate and tidal volume. Transthoracic impedance monitoring measures respiratory rate, and may assist in confirmation of endotracheal tube placement. A new mechanical device (CPREzy) and a new defibrillator/monitor allow estimation of depth (and rate) of compressions. Ventricular-fibrillation waveform analysis may facilitate better timing of defibrillation. Echocardiography detects conditions that may impair the quality of cardiopulmonary resuscitation.

SUMMARY

Many options are available to monitor the quality of cardiopulmonary resuscitation. Some have significant limitations, and others are only readily available in hospital. The use of the information from this more intensive monitoring promises to improve outcomes of cardiopulmonary resuscitation.

Prediction of successful defibrillation in human victims of out-of-hospital cardiac arrest: a retrospective electrocardiographic analysis

In the present study we sought to examine the efficacy of an electrocardiographic parameter, 'amplitude spectrum area' (AMSA), to predict the likelihood that any one electrical shock would restore a perfusing rhythm during cardiopulmonary resuscitation in human victims of out-of-hospital cardiac arrest. AMSA analysis is not invalidated by artefacts produced by chest compression and thus it can be performed during CPR, avoiding detrimental interruptions of chest compression and ventilation. We hypothesised that a threshold value of AMSA could be identified as an indicator of successful defibrillation in human victims of cardiac arrest. Analysis was performed on a database of electrocardiographic records, representing lead 2 equivalent recordings from automated external defibrillators including 210 defibrillation attempts from 90 victims of out-of-hospital cardiac arrest. A 4.1 second interval of ventricular fibrillation or ventricular tachycardia, recorded immediately preceding the delivery of the shock, was analysed using the AMSA algorithm. AMSA represents a numerical value based on the sum of the magnitude of the weighted frequency spectrum between two and 48 Hz. AMSA values were significantly greater in successful defibrillation (restoration of a perfusing rhythm), compared to unsuccessful defibrillation (P < 0.0001). An AMSA value of 12 mV-Hz was able to predict the success of each defibrillation attempt with a sensitivity of 0.91 and a specificity of 0.97. In conclusion, AMSA analysis represents a clinically applicable method, which provides a real-time prediction of the success of defibrillation attempts. AMSA may minimise the delivery of futile and detrimental electrical shocks, reducing thereby post-resuscitation myocardial injury.

The quality of chest compressions during cardiopulmonary resuscitation overrides importance of timing of defibrillation

BACKGROUND

We address the quality of chest compressions and the impact on initial defibrillation or initial chest compressions after sudden death.

METHODS

Ventricular fibrillation was induced by occlusion of the left anterior descending coronary artery in 24 domestic pigs with a mean (+/- SD) weight of 40 +/- 2 kg. Cardiac arrest was left untreated for 5 min. Animals were then randomized to receive chest compressions-first or defibrillation-first and were further randomized to "optimal" or "conventional" chest compressions. A total of four groups of animals were investigated using a factorial design. For optimal chest compressions, the anterior posterior diameter of the chest was reduced by 25%, representing approximately 6 cm. Only 70% of this depth, or approximately 4.2 cm, represented conventional chest compressions. Chest compressions were delivered with a mechanical chest compressor. Defibrillation was attempted with a single biphasic 150-J shock. Postresuscitation myocardial function was echocardiographically assessed.

RESULTS

Coronary perfusion pressures and end-tidal Pco(2) were significantly lower with conventional chest compressions. With optimal chest compressions, either as an initial intervention or after defibrillation, each animal was successfully resuscitated. Fewer shocks were required prior to the return of spontaneous circulation after initial optimal chest compressions. No animals were resuscitated when conventional chest compressions preceded the defibrillation attempt. When defibrillation was attempted as the initial intervention followed by conventional chest compressions, two of six animals were resuscitated.

CONCLUSIONS

In this animal model of cardiac arrest, it was the quality of the chest compressions, rather then the priority of either initial defibrillation or initial chest compressions, that was the predominant determinant of successful resuscitation.

The impact of manual defibrillation technique on no-flow time during simulated cardiopulmonary resuscitation

INTRODUCTION

Rapid defibrillation is the most effective strategy for establishing return of spontaneous circulation following cardiac arrest due to ventricular fibrillation. The aim of this study is to measure the delay due to of charging the defibrillator during chest compression in an attempt to reduce the duration of the pre-shock pause in between cessation of chest compressions and shock delivery as advocated by the American Heart Association (AHA) guidelines compared to charging the defibrillator immediately following rhythm analysis without resuming chest compressions as recommended by the European Resuscitation Council (ERC).

METHODS

This was a randomised controlled cross over trial comparing pre-shock pause times when defibrillation was performed on a manikin according to the AHA and ERC guidelines using paddles and hands free defibrillation systems.

RESULTS

The pre-shock pause between cessation of chest compression and shock delivery was significantly different between techniques (Friedman test, P<0.0001). ERC paddles technique had the greatest pre-shock pause (7.4 s [6.7-11.2]) followed by ERC hands free (7.0 s [6.5-8.5]) and AHA paddles (1.6 s [1.1-2.3]). AHA hands free took the least amount of time (1.5 s [0.8-1.5]). Extrapolating these data to older defibrillators with longer charge times saw pre-shock pause intervals of 9 s (Codemaster XL) and 12 s (Lifepak 20) with the ERC approach.

CONCLUSION

This study demonstrated clinically significant delays to defibrillation by analysing and charging the defibrillator without performing concurrent chest compressions. In a simulated scenario, charging the defibrillator whilst performing chest compressions was perceived as safe and significantly reduced the pre-shock pause between cessation of chest compression and shock delivery.

[Automated external defibrillation in children]

Ventricular fibrillation is an infrequent arrhythmia in cardiac arrest occurring in the out-of-hospital setting in infants and small children. However, outcome is good provided early defibrillation is performed; consequently, this procedure is one of the main links in the chain of survival in children with a shockable rhythm. Automated external defibrillators are small devices that can analyze heart rhythm and deliver a dose of electric energy when considered timely by the operator. Automated external defibrillators are easy to use and can be operated, if necessary, by anyone. Therefore, all pediatricians should be aware of how these devices work and be able to use them safely and effectively, following the current defibrillation protocol.

A prospective study of outcome of in-patient paediatric cardiopulmonary arrest

BACKGROUND

Few prospective studies of the incidence and outcome of paediatric in-hospital cardiopulmonary arrest have been reported to enable quality assurance comparisons within and between institutions.

METHODS

All cardiac and respiratory arrests and their management over a 41-month period in children not subject to palliative treatment or to a 'do not resuscitate' order were recorded and analysed using the Utstein template.

RESULTS

Cardiac arrest occurred in a total of 111 of 104,780 admissions (1.06/1000) while respiratory arrest alone occurred in 36 (0.34/1000). Return of spontaneous circulation (ROSC) was achieved in 81 patients (73%) in cardiac arrest but only 40 (36%) were discharged from hospital and 38 (34%) survived for 1 year. The 1-year survival from respiratory arrest alone was 97%. Cardiac arrest was four times more common (89 versus 22) and approximately 90 times the incidence in the intensive care unit compared with wards but 1-year survival was similar (34% versus 36%). The initial heart rhythms were hypotensive-bradycardia in 73 (66%) with 38% survival; asystole in 17 (15%) with 12% survival; ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) in 10 (9%) with 40% survival; pulseless electrical activity (PEA) in 10 (9%) with 30% survival and SVT in 1 with survival. Secondary ventricular fibrillation occurred in 15 children given adrenaline (epinephrine) for treatment of asystole, hypotensive-bradycardia or PEA of whom 11 had received adrenaline in an initial dose of > 15 mcg/kg and 4 had < 15 mcg/kg (P = 0.0013). Eleven of 15 patients (73%) in secondary VF never achieved ROSC.

CONCLUSIONS

In-patient paediatric cardiac arrest has a mediocre outcome with a better outlook if the initial rhythm is hypotensive-bradycardia, VF or pulsatile VT. Doses of adrenaline greater than 15 mcg/kg given for non-shockable rhythms may cause secondary VF which has a worse outcome than primary VF.

New cardiopulmonary resuscitation guidelines 2005: importance of uninterrupted chest compression

The evidence supports quality controlled chest compression as the initial intervention after "sudden death" before attempted defibrillation, if the duration of cardiac arrest is more than 5 minutes. The new guidelines mandate lesser interruptions for ventilation, before and following electrical shocks, and single rather than multiple electrical shocks before resuming chest compression. The new guidelines refocus on uninterrupted chest compression after cardiac arrest of nonasphyxial cause and modifications in practices that reduce the need for interruptions.