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

Debriefing for cardiac arrest

Early data from North America supports the use of educational cardiac arrest debriefing as a strategy to improve the quality of cardiopulmonary resuscitation (CPR) in the hospital setting. As some debriefing approaches are challenging to deliver in the NHS setting, there was a need to develop debriefing approaches that are both effective and suited to NHS working practices. This thesis is modelled on the Medical Research Council framework for the development and evaluation of complex interventions. Undertaken between October 2011 and January 2015, it describes the development and feasibility assessment of three cardiac arrest debriefing approaches, which were specifically designed to be deliverable in NHS hospitals. Development work comprised three work packages (systematic review, process evaluation, qualitative study). These studies provided evidence to support the use of cardiac arrest debriefing, but showed that weekly group debriefing is undeliverable in many NHS hospitals. Through qualitative work, I identified six distinct mechanisms by which debriefing may affect clinical practice. Synthesis of these data led to the development of three cardiac arrest debriefing approaches (monthly group debriefing, individual oral debriefing, written feedback). We tested the feasibility of delivering these interventions by implementing them in three NHS hospitals (one intervention per hospital). In a before/after study, it was demonstrated that, despite practical challenges, interventions were deliverable in NHS hospitals. However, they were found to have no effect on either CPR quality or patient outcome. This finding was attributed to high performance in study hospitals at baseline. This thesis demonstrates that the developed cardiac arrest debriefing interventions are deliverable in NHS hospitals. It has also generated important new theory about the mechanisms by which debriefing may affect clinical practice. This thesis lays the foundation for future work to evaluate the clinical and cost-effectiveness of these cardiac arrest debriefing interventions

The implementation of cardiac arrest treatment recommendations in English acute NHS trusts : a national survey

Purpose of the study: There are approximately 35 000 in-hospital cardiac arrests in the UK each year. Successful resuscitation requires integration of the medical science, training and education of clinicians and implementation of best practice in the clinical setting. In 2015, the International Liaison Committee on Resuscitation (ILCOR) published its latest resuscitation treatment recommendations. It is currently unknown the extent to which these treatment recommendations have been successfully implemented in practice in English NHS acute hospital trusts. Methods: We conducted an electronic survey of English acute NHS trusts to assess the implementation of key ILCOR resuscitation treatment recommendations in relation to in-hospital cardiac arrest practice at English NHS acute hospital trusts. Results: Of 137 eligible trusts, 73 responded to the survey (response rate 53.3%). The survey identified significant variation in the implementation of ILCOR recommendations. In particular, the use of waveform capnography (n=33, 45.2%) and ultrasound (n=29, 39.7%) was often reported to be available only in specialist areas. Post-resuscitation debriefing occurs following every in-hospital cardiac arrest in few trusts (5.5%, n=4), despite a strong ILCOR recommendation. In contrast, participation in a range of quality improvement strategies such as the National Cardiac Arrest Audit (90.4%, n=66) and resuscitation equipment provision/audit (91.8%, n=67) were high. Financial restrictions were identified by 65.8% (n=48) as the main barrier to guideline implementation. Conclusion: Our survey found that ILCOR treatment recommendations had not been fully implemented in most English NHS acute hospital trusts. Further work is required to better understand barriers to implementation

Is protocolised weaning that includes early extubation onto non-invasive ventilation more cost effective than protocolised weaning without non-invasive ventilation? Findings from the Breathe Study

Background Optimising techniques to wean patients from invasive mechanical ventilation (IMV) remains a key goal of intensive care practice. The use of non-invasive ventilation (NIV) as a weaning strategy (transitioning patients who are difficult to wean to early NIV) may reduce mortality, ventilator-associated pneumonia and intensive care unit (ICU) length of stay. Objectives Our objectives were to determine the cost effectiveness of protocolised weaning, including early extubation onto NIV, compared with weaning without NIV in a UK National Health Service setting. Methods We conducted an economic evaluation alongside a multicentre randomised controlled trial. Patients were randomised to either protocol-directed weaning from mechanical ventilation or ongoing IMV with daily spontaneous breathing trials. The primary efficacy outcome was time to liberation from ventilation. Bivariate regression of costs and quality-adjusted life-years (QALYs) provided estimates of the incremental cost per QALY and incremental net monetary benefit (INMB) overall and for subgroups [presence/absence of chronic obstructive pulmonary disease (COPD) and operative status]. Long-term cost effectiveness was determined through extrapolation of survival curves using flexible parametric modelling. Results NIV was associated with a mean INMB of £620 ($US885) (cost-effectiveness threshold of £20,000 per QALY) with a corresponding probability of 58$US6594 per QALY gained). Conclusions The probability of NIV being cost effective relative to weaning without NIV ranged between 57 and 59% overall and between 82 and 87% for the COPD subgroup

Mechanical chest compression for out of hospital cardiac arrest: Systematic review and meta-analysis

Aim: To summarise the evidence from randomised controlled trials of mechanical chest compression devices used during resuscitation after out of hospital cardiac arrest. Methods: Systematic review of studies evaluating the effectiveness of mechanical chest compression. We included randomised controlled trials or cluster randomised trials that compared mechanical chest compression (using any device) with manual chest compression for adult patients following out-of-hospital cardiac arrest. Outcome measures were return of spontaneous circulation, survival of event, overall survival, survival with good neurological outcome. Results were combined using random-effects meta-analysis. Data sources: Studies were identified by searches of electronic databases, reference lists of other studies and review articles. Results: Five trials were included, of which three evaluated the LUCAS or LUCAS-2 device and two evaluated the AutoPulse device. The results did not show an advantage to the use of mechanical chest compression devices for survival to discharge/30 days (average OR 0.89, 95% CI 0.77, 1.02) and survival with good neurological outcome (average OR 0.76, 95% CI 0.53, 1.11). Conclusions: Existing studies do not suggest that mechanical chest compression devices are superior to manual chest compression, when used during resuscitation after out of hospital cardiac arrest

Evolution of European Resuscitation and End-of-Life Practices from 2015 to 2019 : a survey-based comparative evaluation

In concordance with the results of large, observational studies, a 2015 European survey suggested variation in resuscitation/end-of-life practices and emergency care organization across 31 countries. The current survey-based study aimed to comparatively assess the evolution of practices from 2015 to 2019, especially in countries with "low" (i.e., average or lower) 2015 questionnaire domain scores. The 2015 questionnaire with additional consensus-based questions was used. The 2019 questionnaire covered practices/decisions related to end-of-life care (domain A); determinants of access to resuscitation/post-resuscitation care (domain B); diagnosis of death/organ donation (domain C); and emergency care organization (domain D). Responses from 25 countries were analyzed. Positive or negative responses were graded by 1 or 0, respectively. Domain scores were calculated by summation of practice-specific response grades. Domain A and B scores for 2015 and 2019 were similar. Domain C score decreased by 1 point [95% confidence interval (CI): 1-3; = 0.02]. Domain D score increased by 2.6 points (95% CI: 0.2-5.0; = 0.035); this improvement was driven by countries with "low" 2015 domain D scores. In countries with "low" 2015 domain A scores, domain A score increased by 5.5 points (95% CI: 0.4-10.6; = 0.047). In 2019, improvements in emergency care organization and an increasing frequency of end-of-life practices were observed primarily in countries with previously "low" scores in the corresponding domains of the 2015 questionnaire

Approximating the Geisser-Greenhouse sphericity estimator and its applications to diffusion tensor imaging

The diffusion tensor imaging (DTI) protocol characterizes diffusion anisotropy locally in space, thus providing rich detail about white matter tissue structure. Although useful metrics for diffusion tensors have been defined, statistical properties of the measures have been little studied. Assuming homogeneity within a region leads to being able to apply Wishart distribution theory. First, it will be shown that common DTI metrics are simple functions of known test statistics. The average diffusion coefficient (ADC) corresponds to the trace of a Wishart, and is also described as the generalized (multivariate) variance, the average variance of the principal components. Therefore ADC has a known exact distribution (a positively weighted quadratic form in Gaussians) as well as a simple and accurate approximation (Satterthwaite) in terms of a scaled chi square. Of particular interest is that fractional anisotropy (FA) values for given regions of interest are functions of the Geisser-Greenhouse (GG) sphericity estimator. The GG sphericity estimator can be approximated well by a linear transformation of a squared beta random variable. Simulated data demonstrates that the fits work well for simulated diffusion tensors. Applying traditional density estimation techniques for a beta to histograms of FA values from a region allow representing the histogram of hundreds or thousands of values in terms of just two estimates for the beta parameters. Thus using the approximate distribution eliminates the “curse of dimensionality” for FA values. A parallel result holds for ADC

Mechanical versus manual chest compressions in the treatment of in-hospital cardiac arrest patients in a non-shockable rhythm : a randomised controlled feasibility trial (COMPRESS-RCT)

Background Mechanical chest compression devices consistently deliver high-quality chest compressions. Small very low-quality studies suggest mechanical devices may be effective as an alternative to manual chest compressions in the treatment of adult in-hospital cardiac arrest patients. The aim of this feasibility trial is to assess the feasibility of conducting an effectiveness trial in this patient population. Methods COMPRESS-RCT is a multi-centre parallel group feasibility randomised controlled trial, designed to assess the feasibility of undertaking an effectiveness to compare the effect of mechanical chest compressions with manual chest compressions on 30-day survival following in-hospital cardiac arrest. Over approximately two years, 330 adult patients who sustain an in-hospital cardiac arrest and are in a non-shockable rhythm will be randomised in a 3:1 ratio to receive ongoing treatment with a mechanical chest compression device (LUCAS 2/3, Jolife AB/Stryker, Lund, Sweden) or continued manual chest compressions. It is intended that recruitment will occur on a 24/7 basis by the clinical cardiac arrest team. The primary study outcome is the proportion of eligible participants randomised in the study during site operational recruitment hours. Participants will be enrolled using a model of deferred consent, with consent for follow-up sought from patients or their consultee in those that survive the cardiac arrest event. The trial will have an embedded qualitative study, in which we will conduct semi-structured interviews with hospital staff to explore facilitators and barriers to study recruitment. Discussion The findings of COMPRESS-RCT will provide important information about the deliverability of an effectiveness trial to evaluate the effect on 30-day mortality of routine use of mechanical chest compression devices in adult in-hospital cardiac arrest patients

Patient, health service factors and variation in mortality following resuscitated out-of-hospital cardiac arrest in acute coronary syndrome : analysis of the Myocardial Ischaemia National Audit Project

Aims To determine patient and health service factors associated with variation in hospital mortality among resuscitated cases of out-of-hospital cardiac arrest (OHCA) with acute coronary syndrome (ACS). Methods In this cohort study, we used the Myocardial Ischaemia National Audit Project database to study outcomes in patients hospitalised with resuscitated OHCA due to ACS between 2003 and 2015 in the United Kingdom. We analysed variation in inter-hospital mortality and used hierarchical multivariable regression models to examine the association between patient and health service factors with hospital mortality. Results We included 17604 patients across 239 hospitals. Overall hospital mortality was 28.7%. In 94 hospitals that contributed at least 60 cases, mortality by hospital ranged from 10.7% to 66.3% (median 28.6%, IQR 23.2% to 39.1%)). Patient and health service factors explained 36.1% of this variation. After adjustment for covariates, factors associated with higher hospital mortality included increasing serum glucose, ST-Elevation myocardial infarction (STEMI) diagnosis, and initial admission to a primary percutaneous coronary intervention (pPCI) capable hospital. Hospital OHCA volume was not associated with mortality. The key modifiable factor associated with lower mortality was early reperfusion therapy in STEMI patients. Conclusion There was wide variation in inter-hospital mortality following resuscitated OHCA due to ACS that was only partially explained by patient and health service factors. Hospital OHCA volume and pPCI capability were not associated with lower mortality. Early reperfusion therapy was associated with lower mortality in STEMI patients