Realist synthesis : illustrating the method for implementation research

BackgroundRealist synthesis is an increasingly popular approach to the review and synthesis of evidence, which focuses on understanding the mechanisms by which an intervention works (or not). There are few published examples of realist synthesis. This paper therefore fills a gap by describing, in detail, the process used for a realist review and synthesis to answer the question \u27what interventions and strategies are effective in enabling evidence-informed healthcare?\u27 The strengths and challenges of conducting realist review are also considered. MethodsThe realist approach involves identifying underlying causal mechanisms and exploring how they work under what conditions. The stages of this review included: defining the scope of the review (concept mining and framework formulation); searching for and scrutinising the evidence; extracting and synthesising the evidence; and developing the narrative, including hypotheses. ResultsBased on key terms and concepts related to various interventions to promote evidenceinformed healthcare, we developed an outcome-focused theoretical framework. Questions were tailored for each of four theory/intervention areas within the theoretical framework and were used to guide development of a review and data extraction process. The search for literature within our first theory area, change agency, was executed and the screening procedure resulted in inclusion of 52 papers. Using the questions relevant to this theory area, data were extracted by one reviewer and validated by a second reviewer. Synthesis involved organisation of extracted data into evidence tables, theming and formulation of chains of inference, linking between the chains of inference, and hypothesis formulation. The narrative was developed around the hypotheses generated within the change agency theory area. ConclusionsRealist synthesis lends itself to the review of complex interventions because it accounts for context as well as outcomes in the process of systematically and transparently synthesising relevant literature. While realist synthesis demands flexible thinking and the ability to deal with complexity, the rewards include the potential for more pragmatic conclusions than alternative approaches to systematic reviewing. A separate publication will report the findings of the review. <br /

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Surviving out-of-hospital cardiac arrest: the important role of bystander interventions

Background: Substantial variations exist in relation to the characteristics and outcomes of out-of-hospital cardiac arrest (OHCA). As such, an understanding of region-specific factors is essential for informing strategies to improve OHCA survival. Methods: Analysis of a large state-wide OHCA database of the Queensland Ambulance Service, Australia. Adult patients, attended by paramedics between January 2000 and December 2018 for OHCA of medical origin, where the arrest was not witnessed by paramedics, and resuscitation was attempted, were included. Factors associated with survival were investigated. The number needed to treat (NNT) for bystander interventions was estimated. Results: Across a total of 23,510 patients, event survival, survival to discharge and 30-day survival was 22.6%, 11.9% and 11.5%, respectively. The corresponding figures for the Utstein patient group (initial shockable rhythm, bystander-witnessed) were 38.9%, 27.2% and 26.3%, respectively. Bystander cardiopulmonary resuscitation (CPR) and defibrillation substantially improved the likelihood of survival. The NNT for bystander CPR was 41, 63 and 64 for event survival, survival to discharge, and 30-day survival, respectively. The NNT for bystander defibrillation for these survival outcomes was 10, 14 and 14, respectively. Conclusions: Bystander interventions are critical for OHCA survival. Effort should be invested in strategies to improve the uptake of these interventions

Epidemiology of out-of-hospital cardiac arrests that occur secondary to chemical asphyxiants: A retrospective series

Aim: To determine the epidemiological characteristics, temporal trends and survival outcomes of OHCAs precipitated by chemical asphyxiation. Methods: We conducted a retrospective cohort analysis of OHCAs attended by paramedics in Queensland, Australia between 2011 and 2020. Patients were classified into two groups depending on the asphyxiating agent involved; simple (argon, carbon dioxide, helium, liquified petroleum gas, nitrogen) and systemic (carbon monoxide, cyanides, hydrogen sulfide, methemoglobin-inducing substances, smoke inhalation). Incidence rates, characteristics and outcomes were described for the entire cohort and independently for each group, with the groups then compared. Temporal trends of asphyxiant utilisation were also described. Results: During the study period, 50,669 OHCAs were attended, with 551 (1.1%) attributable to chemical asphyxiation. The incidence rate was 1.1 per 100,000 population with no significant temporal changes. Suspected suicide was the primary cause of exposure (-95.8%), with systemic asphyixants the dominant agent reported in comparison to simple agents (66.4% vs 33.6%). Over the 10-year period, events precipitated by carbon monoxide decreased by 26.2% (p for trend < 0.001), helium remained unchanged (p for trend = 0.302) and incidents involving nitrogen increased by 28.7% (p for trend < 0.001). Overall, 14.2% (78/551) of the study cohort received a resuscitation attempt by paramedics with 6.4% of these incidents witnessed and 2.6% involving patients presenting in a shockable rhythm. Survival rates were low, with 6.4% surviving the index event, and 1.3% surviving to hospital discharge with a normal neurocognitive function. Conclusion: OHCA precipitated by chemical asphyxiation is relatively infrequent and associated with poor survival outcomes.</p

Epidemiology of Oxytocin Administration in Out-of-Hospital Births Attended by Paramedics

Aim: Primary postpartum hemorrhage (PPH) is a life-threatening obstetric emergency that can be mitigated through the administration of a uterotonic to actively manage the third stage of labor. This study describes the prehospital administration of oxytocin by paramedics following attendance of out-of-hospital (OOH) births. Methods: A retrospective analysis was undertaken of all OOH births between the 1st January 2018 and 31st December 2018 attended by the Queensland Ambulance Service. The demographic and epidemiological characteristics of patients that were administered oxytocin and the occurrence of adverse side effects were described. Results: In total, 350 OOH births were included in this study with the majority involving multigravidas women (94.3%) and all but two involving singleton pregnancies. Oxytocin was administered following 222 births (63.4%), while 67 patients (19.1%) declined administration preferring a physiological third stage of labor, and in 61 cases (17.4%) oxytocin was withheld by the attending paramedic. There were no documented adverse events or side effects following administration. Oxytocin administration occurred on average 14 minutes (interquartile range 9-25) following the time of birth. The median time from oxytocin administration to placenta delivery was 10 minutes (interquartile range 5-22). Conclusion: Oxytocin is well accepted and safe treatment adjunct for the management of the third stage of labor in OOH births and should be considered for routine practice by other emergency medical services.</p

Epidemiology of open limb fractures attended by ambulance clinicians in the out-of-hospital setting: A retrospective analysis

Background: Open limb fractures are a time-critical orthopaedic emergency that present to jurisdictional ambulance services. This study describes the demographic characteristics and epidemiological profile of these patients. Methods: We undertook a retrospective analysis of all patients that presented to Queensland Ambulance Service with an open limb fracture (fracture to the humerus, radius/ulna, tibia/fibula or femur) over a two-year period (January 2018 – December 2019). Results: Overall, 1020 patients were included. Patients were mainly male (65.9%) and middle-aged (age 41 years, IQR 22–59). Fractures predominately occurred in the lower extremities (64.9%) with transport crashes the primary mechanism of injury (47.8%). The location of the fracture varied depending on the cause of injury, with femur fractures associated with motorcycle crashes, and fractures to the radius/ulna attributed to falls of greater than one metre (p = 0.001). The median prehospital episode of care was 83 min (IQR 62–144) with aeromedical air ambulance involvement and the attendance of a critical care paramedic or emergency physician, both independent factors that increased this time interval. Conclusion: Open limb fractures are a relatively infrequent injury presentation encountered by ambulance clinicians. The characteristics of these patients is consistent with previously described national and international out-of-hospital trauma cohort

Prehospital study of survival outcomes from out-of-hospital cardiac arrest in ST-elevation myocardial infarction in Queensland, Australia (the PRAISE study)

AimPatients that experience an out-of-hospital cardiac arrest in the context of a paramedic-identified ST-segment elevation myocardial infarction are a unique cohort. This study identifies the survival outcomes and determinants of survival in these patients.MethodsA retrospective analysis was undertaken of all patients, attended between 1 January 2013 and 31 December 2017 by the Queensland Ambulance Service, who had a ST-segment elevation myocardial infarction identified by the attending paramedic prior to deterioration into out-of-hospital cardiac arrest. We described the ‘survived event’ and ‘survived to discharge’ outcomes of patients and performed univariate analysis and multivariate logistic regression to identify factors associated with survival.ResultsIn total, 287 patients were included. Overall, high rates of survival were reported, with 77% of patients surviving the initial out-of-hospital cardiac arrest event and 75% surviving to discharge. Predictors of event survival were the presence of an initial shockable rhythm (adjusted odds ratio 8.60, 95% confidence interval (CI) 4.16–17.76; P ConclusionThis subset of out-of-hospital cardiac arrest patients was found to be highly salvageable and responsive to resuscitative measures, having arrested in the presence of paramedics and presented with an identified reversible cause

Time to amiodarone administration and survival outcomes in refractory ventricular fibrillation

Objective: International guidelines recommend amiodarone for out-of-hospital cardiac arrest (OHCA) in refractory ventricular fibrillation (VF). While early appropriate interventions have been shown to improve OHCA survival, the association between time to amiodarone and survival remains to be established. Methods: Included were adult OHCA in refractory VF, between January 2015 and December 2019, who received a resuscitation attempt with amiodarone from Queensland Ambulance Service paramedics. Patient characteristics and survival outcomes were described. Factors associated with survival were investigated, with a focus on time from arrest to amiodarone administration. Optimal time window for amiodarone administration was determined, and factors influencing whether amiodarone was given within the optimal time window were examined. Results: A total of 502 patients were included. The average (range) time from arrest to amiodarone was 25 (4–83) min. Time to amiodarone was negatively associated with survival (adjusted odds ratio 0.93 for event survival; 95% confidence interval 0.89–0.97). The optimal time window for amiodarone was within 23 min following arrest. Patients receiving amiodarone within the optimal time had significantly better survival than those receiving it outside this window (event survival 38.3% vs 20.6%, P < 0.001; discharge survival 25.5% vs 9.7%, P < 0.001; 30-day survival 25.1% vs 9.7%, P < 0.001). Paramedic response time (adjusted odds ratio 0.96; 95% confidence interval 0.92–0.99) and time from arrest to intravenous access (0.71; 0.67–0.76) were independent factors determining whether patients received amiodarone within the optimal time. Conclusions: Earlier amiodarone administration was associated with improved survival. Strategies aimed at reducing delay to amiodarone administration have the potential to improve outcome.</p

Insights into the epidemiology of cardiopulmonary resuscitation-induced consciousness in out-of-hospital cardiac arrest

Objectives To describe the characteristics and outcomes of cardiopulmonary resuscitation (CPR)-induced consciousness patients from a large database of out-of-hospital cardiac arrest (OHCA). Methods Included were adult patients, attended between January 2007 and December 2018 by the Queensland Ambulance Service, where resuscitation was attempted by paramedics. Manual review of records was undertaken to identify CPR-induced consciousness cases. Patients exhibiting purposeful limb/body movement during CPR, with or without displaying other signs, were considered to be CPR-induced consciousness. Characteristics and outcomes of CPR-induced consciousness patients were compared to those without CPR-induced consciousness. Results A total of 23 011 OHCA patients were included; of these, 52 (0.23%) were CPR-induced consciousness. This translates into an incidence rate of 2.3 cases per 1000 adult resuscitation attempts over 12 years. Combativeness/agitation was the most common sign of CPR-induced consciousness, described in 34.6% (18/52) of patients. CPR-induced consciousness patients had numerically higher rates of return of spontaneous circulation on hospital arrival (51.9% vs 28.6%), discharge survival (46.2% vs 15.1%) and 30-day survival (46.2% vs 14.7%), than those without CPR-induced consciousness; however, CPR-induced consciousness was not found to be an independent predictor of survival. Higher proportions of CPR-induced consciousness patients had arrest witnessed by paramedics, occurring in public places, of cardiac aetiology and initial shockable rhythm, than patients without CPR-induced consciousness. Conclusions CPR-induced consciousness in OHCA appears to be associated with higher survival rates. Standardised guidelines on recognition and management of CPR-induced consciousness remain to be established

Prehospital ST-Segment Elevation Myocardial Infarction (STEMI) in Queensland, Australia: Findings from 11 Years of the Statewide Prehospital Reperfusion Strategy

Background: Field identification and treatment of ST-segment elevation myocardial infarction (STEMI) by paramedics is an important component of the continuum of care for these patients. This study described real-world clinical practice in prehospital management of STEMI patients in Queensland, Australia. Methods: Retrospective analysis of data sourced from the STEMI database of the Queensland Ambulance Service, Australia. Adult STEMI patients identified by paramedics between February 2008 and December 2018 in Queensland were included. Key aspects of prehospital STEMI care were described. Clinically-important time intervals from symptom onset to reperfusion were reported. Results: A total of 8,388 patients were included. The proportion of patients receiving prehospital reperfusion treatment has improved markedly, increasing from 34% in 2008 to 65% in 2018 (p < 0.001). Direct referral of patients to a hospital for primary percutaneous coronary intervention (pPCI), and administration of preparatory antiplatelet and anticoagulant medications, was the main reperfusion treatment pathway, accounting for 75% of patients receiving reperfusion treatment. Time from paramedic arrival at scene to first 12-lead electrocardiogram has significantly reduced, from 11 minutes in 2008 to 6 minutes from 2012 onwards (p < 0.001). Median (interquartile range, IQR) time from prehospital STEMI identification to reperfusion was 88 (74–103) minutes for patients referred by paramedics to a hospital for pPCI. Fifty-five percent of patients who underwent pPCI achieved time from STEMI identification to reperfusion within 90 minutes. For patients receiving prehospital fibrinolysis, median (IQR) time from STEMI identification to administration of a fibrinolytic agent was 21 (12–33) minutes. Conclusion: The implementation of a statewide prehospital reperfusion strategy has markedly improved the rate of prehospital reperfusion treatment and key time metrics. Ongoing quality improvement efforts are required to further reduce delays in reperfusion.</p