Effectiveness of using automated external defibrillator by trained healthcare professionals on survival outcomes among adult patients after in-hospital cardiac arrest: a systematic review.

Abstract

Review question/objective The objective of this review is to synthesise the best available evidence of the effectiveness of using automated external defibrillator by trained healthcare professionals on survival outcomes in adult patients after in-hospital cardiac arrest. More specifically, the objectives are to identify: the effectiveness of using automated external defibrillator by trained healthcare professionals on return of spontaneous circulation and survival to hospital discharge in adult patients after in-hospital cardiac arrest. Background Cardiac arrest is defined as cessation of cardiac mechanical activity and is confirmed by the absence of signs of circulation.1, 2 The available statistics report that the annual incidence of out-of-hospital cardiac arrest in North America is approximately 0.55 per 1000 population.1 It means the occurrence of out-of-hospital cardiac arrest was approximately 166,200 among an estimated American population of 302,196,872.1 conversely, a recent statistic estimates approximately 200,000 incidences of cardiac arrests are reported annually in hospitalised patients throughout America. 3 Globally, the incidence of death resulting from cardiac arrest is estimated between 4-5 million yearly.4 The burden of cardiac arrest is enormous. Understanding the aetiology of cardiac arrest is essential to strategise corrective measures. The most commonly reported aetiologies of cardiac arrests are cardiac arrhythmias, acute respiratory failure and hypotension.5 The causes of cardiac arrests could vary according to the age group. Among 0-17 years old, the most common cause of cardiac arrest was due to sudden infant death syndrome (52%).6 Ischaemic heart disease (IHD) accounted for 24% of cardiac arrest between aged 18-35 years old. 6 Similarly for age 36 years and above, 81% of cardiac arrest was caused by IHD. IHD and heart failure are identified as the top pathology of cardiac arrest in the United States.7 Therefore, one of the measures to improve survival is by introducing the concept of “chain of survival”. “Chain of survival” was firstly introduced in 1991 to improve survival after sudden cardiac arrest. The elements of the chain of survival include recognition of early warning signs, activation of the emergency medical system, basic cardiopulmonary resuscitation, defibrillation, intubation and intravenous delivery of medications.8 For the purpose of this review, defibrillation will be the focus. Research studies had proven that earlier defibrillation has greatly improved the odds of survival in the range from 3.3 to 6.9.8 In this review, the outcome of survival will be examined in two phases: phase one will measure the immediate effect of use of an automated external defibrillator (AED) on returning of spontaneous circulation within 20 minutes; and phase two will measure the latent effect of AED on patient overall survival to discharge. At one time, a professional rescuer who was trained and certified in defibrillation was required to perform the task. As a consequence, the automated external defibrillator was introduced in order to achieve the goal of earlier defibrillation by more users including laypeople. An automated external defibrillator is a portable, easy-to-operate defibrillator. A systematic review concluded that cardiopulmonary resuscitation plus automated external defibrillator (CPR+AED) significantly offered a survival advantage over cardiopulmonary resuscitation (CPR) alone. This review included three randomised controlled studies among non-healthcare professionals who were trained to respond to out-of-hospital cardiac arrest.9 Operation of AED starts with applying self-adhesive defibrillator pads or electrodes pads to the right upper chest, below the right clavicle and left below the nipple or left breast laterally according to the diagram provided in the AED kit. It will automatically analyse and interpret the heart rhythms within a minute.10 Subsequently, through the audible voice, it will recommend the operator to deliver the shock by pushing a button or continue with CPR. 11 Depending on the specification of the AED, some deliver 200 Joules (J) at the first shock followed by maximum of 360J.12 Some have 150J set as a fixed dose. The AED is highly specific and sensitive in recognising the shockable and non-shockable rhythms.13 The shockable rhythms are ventricular tachycardia (VT) and ventricular fibrillation (VF). The non-shockable rhythms are pulseless electrical activity (PEA) and asystole. Therefore, it is essential to quantify and qualify the cardiac rhythms while patients experience cardiac arrest to further justify the employment of AED in hospital setting. Earlier defibrillation with AED has significantly improved the survival of the victims who suffer from an out-of-hospital cardiac arrest. The probability of survival drops by 7-10% of every minute delay in defibrillation for shockable rhythms. 10 As a result, AED is highly recommended to be deployed in the community. 10 The advantages of AED have also extended its application in the hospital setting.10 To shorten time to first shock within three minutes of collapse, the American Heart Association has recommended use of AED, especially by nurses who are most likely to be the first responding to a cardiac arrest in the hospital. However, one study reported that nurses using AED could be potentially less useful in inpatient settings because only 1 in 5 hospitalised patients have initial cardiac arrest rhythms that would respond to defibrillation. 14 Based on the National Registry Cardiopulmonary Resuscitation in the United States, only 16% of in-hospital cardiac arrest victims presented with ventricular fibrillation (VF) which is the shockable rhythm.5 In the same study, the utilisation of AED was only 1.4% of patients with VF. In addition, manual application of defibrillator pads and waiting for the AED to determine the “shockable” rhythms will interrupt the continuation of chest compression that could adversely affect the survival outcome.14 Use of AED is currently widespread in hospitals. Nurses are trained and recertified regularly to use AED and /or in combination with cardiopulmonary resusciation. 15, 16 However, barriers to provide defibrillation are also frequently reported. They were lack of confidence, fear of incurring litigation and harming the patients, and perceived difficulty in interpreting rhythms. 17 The benefit of using AED on improving pre-hospital cardiac arrest survival is evident in the literature. However, effectiveness of AED in situations of after-hospital cardiac arrest is uncertain. One Singaporean hospital reported that during resuscitation for cardiac arrest, a return of spontaneous circulation was 63.8% but the survival-to-discharge rate was only 13.1%.15 There are diverse opinions and conclusions drawn from the literature.12,14, 18–21 The preliminary search identified a systematic review published in 2002 to evaluate the effectiveness of AED by nurses on survival-to-discharge rate in hospital.22 The survival rate in the studies included in this review ranged from 26%-100%. These results required cautious interpretation because the individual study which reported a 100% survival rate only had one patient who used the AED and survived the cardiac arrest. Besides, the included studies in this systematic review were heterogeneous as the review had included AED compared with multiple interventions such as manual defibrillator, manual defibrillator and telemetry, AED and telemetry. This existing systematic review22 included studies with poor methodological quality and unclear evidence in supporting the use of AED in the hospital setting. This proposed systematic review will aim to conduct a high quality review focusing on survival rate of adult patients who suffered after-hospital cardiac arrest and received defibrillation by automated external defibrillator or manual defibrillator. Inclusion criteria Types of participants This review will consider studies that include adults 18 years old and above; suffering from cardiac arrest requiring chest compression in in-patient wards, emergency department and out-patient procedures in hospital; presenting with an initial index pulseless (for example, but not limited to, ventricular fibrillation and pulseless ventricular tachycardia, asystole or pulseless electrical activities); presence or absence of co-morbidities such as congestive heart failure, myocardial infarction, diabetes mellitus, renal, hepatic or respiratory insufficiency, motor, cognitive or functional deficits, acute stroke, acute non-stroke neurological disorder, pneumonia, hypotension, sepsis, major trauma, metabolic or electrolyte abnormality, metastatic or haematology malignancy. The exclusion criteria are any age group who suffered out-of-hospital cardiac arrest or adults 18 years old and above suffered in-hospital cardiac arrest with a ‘do not resuscitate’ order (DNR). Types of intervention(s) This review will consider as interventions any use of commercially available automated external defibrillator by trained healthcare professionals for in-hospital cardiac arrest. The comparator of interest is use of manual/standard external defibrillator by trained healthcare professionals for in-hospital cardiac arrest. Types of outcomes This review will consider studies that include the following outcome measures: 1. survival with a return of spontaneous circulation for at least 20 minutes during resuscitation 2. survival to hospital discharge regardless of time to discharge 3. initial cardiac arrest rhythms Types of studies This review will consider for inclusion any experimental study design including randomised controlled trials, non-randomised controlled trials, quasi-experimental including before and after studies. Search strategy The search strategy aims to find both published and unpublished studies. A three-step search strategy will be utilised in this review. An initial limited search of MEDLINE and CINAHL will be undertaken followed by analysis of the text words contained in the title and abstract, and of the index terms used to describe article. A second search using all identified keywords and index terms will then be undertaken across all included databases. Thirdly, the reference list of all identified reports and articles will be searched for additional studies. Studies published in all languages will be considered for inclusion in this review, subject to availability of translation assistance. Studies published from 2001 to 2012 will be considered for inclusion in this review because the search limit for the existing systematic review on the topic was up until the year 2000. The databases to be searched include: Medline CINAHL Embase Web of knowledge Scopus Cochrane Central Register of Controlled Trials Agency for Healthcare Research and Quality (AHRQ) The search for unpublished studies will include: ProQuest Dissertations and Theses Mednar (first 100 articles identified by the search) US National Institutes of Health, clinical trials Initial keywords to be used will be: automated external defibrillator, cardiac arrest, hospital, adult Assessment of methodological quality Papers selected for retrieval will be assessed by two independent reviewers for methodological validity prior to inclusion in the review using standardised critical appraisal instruments from the Joanna Briggs Institute Meta Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI) (Appendix I). Any disagreements that arise between the reviewers will be resolved through discussion, or with a third reviewer. Data collection Data will be extracted from papers included in the review using the standardised data extraction tool from JBI-MAStARI (Appendix II). The data extracted will include specific details about the interventions, populations, study methods and outcomes of significance to the review question and specific objectives. Data synthesis Quantitative data will, where possible, be pooled in statistical meta-analysis using JBI-MAStARI. All results will be subject to double data entry. Effect sizes expressed as odds ratio (for categorical data) and weighted mean differences (for continuous data) and their 95% confidence intervals will be calculated for analysis. Heterogeneity will be assessed statistically using the standard Chi-square. Where statistical pooling is not possible the findings will be presented in narrative form including tables and figures to aid in data presentation where appropriate. Conflicts of interest The reviewers have no conflicts of interest.