Mechanical chest-compression devices: current and future roles

Purpose of review: It is recognised that the quality of CPR is an important predictor of outcome from cardiac arrest yet studies consistently demonstrate that the quality of CPR performed in real life is frequently sub-optimal. Mechanical chest compression devices provide an alternative to manual CPR. This review will consider the evidence and current indications for the use of these devices. Recent findings: Physiological and animal data suggest that mechanical chest compression devices are more effective than manual CPR. However there is no high quality evidence showing improved outcomes in humans. There are specific circumstances where it may not be possible to perform manual CPR effectively e.g. during ambulance transport to hospital, en-route to and during cardiac catheterisation, prior to organ donation and during diagnostic imaging where using these devices may be advantageous. Summary: There is insufficient evidence to recommend the routine use of mechanical chest compression devices. There may be specific circumstances when CPR is difficult or impossible where mechanical devices may play an important role in maintaining circulation. There is an urgent need for definitive clinical and cost effectiveness trials to confirm or refute the place of mechanical chest compression devices during resuscitation

Improving outcomes from in-hospital cardiac arrest

Over 200 000 adults a year sustain a cardiac arrest while in hospital in the United States.1 Most trials have taken place outside hospital,2 yet the aetiology, patient characteristics, time to treatment, and outcomes are quite different to cardiac arrests occurring in inpatients. Clinical guidelines for in-hospital resuscitation are therefore mainly drawn from the extrapolation of findings from out-of-hospital trials, observational studies, and consensus of expert opinion coordinated through the International Liaison Committee for Resuscitation.3 Given the cost, logistical, and ethical challenges of conducting randomised trials in cardiac arrest, the use of high quality observational data to provide insights into the effectiveness of treatments is attractive. The main limitation of observational studies is the risk that the outcome is affected by both the treatment allocation and other factors that influence the treatment allocation. Propensity scoring methods have been growing in popularity as a way of reducing confounding related to measured variables

Exact approximation of Rao-Blackwellised particle filters

Particle methods are a category of Monte Carlo algorithms that have become popular for performing inference in non-linear non-Gaussian state-space models. The class of 'Rao-Blackwellised' particle filters exploits the analytic marginalisation that is possible for some state- space models to reduce the variance of the Monte Carlo estimates. Despite being applicable to only a restricted class of state-space models, such as conditionally linear Gaussian models, these algorithms have found numerous applications. In scenarios where no such analytical integration is possible, it has recently been proposed in Chen et al. [2011] to use 'local' particle filters to carry out this integration numerically. We propose here an alternative approach also relying on \local" particle filters which is more broadly applicable and has attractive theoretical properties. Proof-of-concept simulation results are presented

Improving bystander defibrillation for out-of-hospital cardiac arrest : capability, opportunity and motivation

In this issue of Resuscitation Sondergaard et al. [1] report that the likelihood of receiving bystander defibrillation decreases quickly as the distance from an out-of-hospital cardiac arrest (OHCA) to the nearest Automated External Defibrillator (AED) increases. Bystander automated external defibrillation – when performed – saves lives. The best available data from a recent systematic review and meta-analysis [2] reports that the chances of survival (odds ratio 1.73; 95% confidence interval 1.36–2.18) and favourable neurological outcome (odds ratio 2.12; 95% CI 1.36–3.29) double when defibrillation is undertaken by a bystander

The UK Out of Hospital Cardiac Arrest Outcome (OHCAO) project

Introduction: Reducing premature death is a key priority for the UK National Health Service (NHS). NHS Ambulance services treat approximately 30 000 casesof suspected cardiac arrest each year but survival rates vary. The British Heart Foundation and Resuscitation Council (UK) have funded a structured research programme—the Out of Hospital Cardiac Arrest Outcomes (OHCAO) programme. The aim of the project is to establish the epidemiology and outcome of OHCA, explore sources of variation in outcome and establish the feasibility of setting up a national OHCA registry. Methods and analysis: This is a prospective observational study set in UK NHS Ambulance Services. The target population will be adults and children sustaining an OHCA who are attended by an NHS ambulance emergency response and where resuscitation is attempted. The data collected will be characterised broadly as system characteristics, emergency medical services (EMS) dispatch characteristics, patient characteristics and EMS process variables. The main outcome variables of interest will be return of spontaneous circulation and medium—long-term survival (30 days to 10-year survival). Ethics and dissemination: Ethics committee permissions were gained and the study also has received approval from the Confidentiality Advisory Group Ethics and Confidentiality committee which provides authorisation to lawfully hold identifiable data on patients without their consent. To identify the key characteristics contributing to better outcomes in some ambulance services, reliable and reproducible systems need to be established for collecting data on OHCA in the UK. Reports generated from the registry will focus on data completeness, timeliness and quality. Subsequent reports will summarise demographic, patient, process and outcome variables with aim of improving patient care through focus quality improvement initiatives

In vitro and in vivo effects of salbutamol on neutrophil function in acute lung injury

Background: Intravenous salbutamol (albuterol) reduces lung water in patients with the acute respiratory distress syndrome (ARDS). Experimental data show that it also reduces pulmonary neutrophil accumulation or activation and inflammation in ARDS. Aim: To investigate the effects of salbutamol on neutrophil function. Methods: The in vitro effects of salbutamol on neutrophil function were determined. Blood and bronchoalveolar lavage (BAL) fluid were collected from 35 patients with acute lung injury (ALI)/ARDS, 14 patients at risk from ARDS and 7 ventilated controls at baseline and after 4 days’ treatment with placebo or salbutamol (ALI/ARDS group). Alveolar–capillary permeability was measured in vivo by thermodilution (PiCCO). Neutrophil activation, adhesion molecule expression and inflammatory cytokines were measured. Results: In vitro, physiological concentrations of salbutamol had no effect on neutrophil chemotaxis, viability or apoptosis. Patients with ALI/ARDS showed increased neutrophil activation and adhesion molecule expression compared with at risk-patients and ventilated controls. There were associations between alveolar– capillary permeability and BAL myeloperoxidase (r = 0.4, p = 0.038) and BAL interleukin 8 (r = 0.38, p = 0.033). In patients with ALI/ARDS, salbutamol increased numbers of circulating neutrophils but had no effect on alveolar neutrophils. Conclusion: At the onset of ALI/ARDS, there is increased neutrophil recruitment and activation. Physiological concentrations of salbutamol did not alter neutrophil chemotaxis, viability or apoptosis in vitro. In vivo, salbutamol increased circulating neutrophils, but had no effect on alveolar neutrophils or on neutrophil activation. These data suggest that the beneficial effects of salbutamol in reducing lung water are unrelated to modulation of neutrophil-dependent inflammatory pathways

Regulation of vascular endothelial growth factor bioactivity in patients with acute lung injury

Background: Reduced bioactive vascular endothelial growth factor (VEGF) has been demonstrated in several inflammatory lung conditions including the acute respiratory distress syndrome (ARDS). sVEGFR-1, a soluble form of VEGF-1 receptor, is a potent natural inhibitor of VEGF. We hypothesised that sVEGFR-1 plays an important role in the regulation of the bioactivity of VEGF within the lung in patients with ARDS. Methods: Forty one patients with ARDS, 12 at risk of developing ARDS, and 16 normal controls were studied. Bioactive VEGF, total VEGF, and sVEGFR-1 were measured by ELISA in plasma and bronchoalveolar lavage (BAL) fluid. Reverse transcriptase polymerase chain reaction for sVEGFR-1 was performed on BAL cells. Results: sVEGFR-1 was detectable in the BAL fluid of 48% (20/41) of patients with early ARDS (1.4– 54.8 ng/ml epithelial lining fluid (ELF)) compared with 8% (1/12) at risk patients (p = 0.017) and none of the normal controls (p = 0.002). By day 4 sVEGFR-1 was detectable in only 2/18 ARDS patients (p = 0.008). Patients with detectable sVEGFR-1 had lower ELF median (IQR) levels of bioactive VEGF than those without detectable sVEGFR-1 (1415.2 (474.9–3192) pg/ml v 4761 (1349–7596.6) pg/ml, median difference 3346 pg/ml (95% CI 305.1 to 14711.9), p = 0.016), but there was no difference in total VEGF levels. BAL cells expressed mRNA for sVEGFR-1 and produced sVEGFR-1 protein which increased following incubation with tumour necrosis factor a. Conclusion: This study shows for the first time the presence of sVEGFR-1 in the BAL fluid of patients with ARDS. This may explain the presence of reduced bioactive VEGF in patients early in the course of ARDS

AED training and its impact on skill acquisition, retention and performance : a systematic review of alternative training methods

Introduction The most popular method of training in basic life support and AED use remains instructor-led training courses. This systematic review examines the evidence for different training methods of basic life support providers (laypersons and healthcare providers) using standard instructor-led courses as comparators, to assess whether alternative method of training can lead to effective skill acquisition, skill retention and actual performance whilst using the AED. Method OVID Medline (including Medline 1950-November 2010; EMBASE 1988-November 2010) was searched using “training” OR “teaching” OR “education” as text words. Search was then combined by using AND “AED” OR “automatic external defibrillator” as MESH words. Additionally, the American Heart Association Endnote library was searched with the terms “AED” and “automatic external defibrillator”. Resuscitation journal was hand searched for relevant articles. Results 285 articles were identified. After duplicates were removed, 172 references were reviewed for relevance. From this 22 papers were scrutinized and 18 were included. All were manikin studies. Four LOE 1 studies, seven LOE 2 studies and three LOE 4 studies were supportive of alternative AED training methods. One LOE 2 study was neutral. Three LOE 1 studies provided opposing evidence. Conclusion There is good evidence to support alternative methods of AED training including lay instructors, self directed learning and brief training. There is also evidence to support that no training is needed but even brief training can improve speed of shock delivery and electrode pad placement. Features of AED can have an impact on its use and further research should be directed to making devices user-friendly and robust to untrained layperson

Impact of prehospital care on outcomes in sepsis : a systematic review

Introduction: Sepsis is a common and potentially life-threatening response to an infection. International treatment guidelines for sepsis advocate that treatment be initiated at the earliest possible opportunity. It is not yet clear if very early intervention by ambulance clinicians prior to arrival at hospital leads to improved clinical outcomes among sepsis patients. Methoda: We systematically searched the electronic databases MEDLINE, EMBASE, CINAHL, the Cochrane Library and PubMed up to June 2015. In addition, subject experts were contacted. We adopted the GRADE (grading recommendations assessment, development and evaluation) methodology to conduct the review and follow PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) recommendations to report findings. Results: Nine studies met the eligibility criteria – one study was a randomized controlled trial while the remaining studies were observational in nature. There was considerable variation in the methodological approaches adopted and outcome measures reported across the studies. Because of these differences, the studies did not answer a unique research question and meta-analysis was not appropriate. A narrative approach to data synthesis was adopted. Conclusion: There is little robust evidence addressing the impact of prehospital interventions on outcomes in sepsis. That which is available is of low quality and indicates that prehospital interventions have limited impact on outcomes in sepsis beyond improving process outcomes and expediting the patient’s passage through the emergency care pathway. Evidence indicating that prehospital antibiotic therapy and fluid resuscitation improve patient outcomes is currently lacking. [West J Emerg Med. 2017;17(4)427-437.