Diagnosis of out-of-hospital cardiac arrest by emergency medical dispatch: A diagnostic systematic review.

INTRODUCTION: Cardiac arrest is a time-sensitive condition requiring urgent intervention. Prompt and accurate recognition of cardiac arrest by emergency medical dispatchers at the time of the emergency call is a critical early step in cardiac arrest management allowing for initiation of dispatcher-assisted bystander CPR and appropriate and timely emergency response. The overall accuracy of dispatchers in recognizing cardiac arrest is not known. It is also not known if there are specific call characteristics that impact the ability to recognize cardiac arrest. METHODS: We performed a systematic review to examine dispatcher recognition of cardiac arrest as well as to identify call characteristics that may affect their ability to recognize cardiac arrest at the time of emergency call. We searched electronic databases for terms related to "emergency medical dispatcher", "cardiac arrest", and "diagnosis", among others, with a focus on studies that allowed for calculating diagnostic test characteristics (e.g. sensitivity and specificity). The review was consistent with Grading of Recommendations, Assessment, Development and Evaluation (GRADE) method for evidence evaluation. RESULTS: We screened 2520 article titles, resulting in 47 studies included in this review. There was significant heterogeneity between studies with a high risk of bias in 18 of the 47 which precluded performing meta-analyses. The reported sensitivities for cardiac arrest recognition ranged from 0.46 to 0.98 whereas specificities ranged from 0.32 to 1.00. There were no obvious differences in diagnostic accuracy between different dispatching criteria/algorithms or with the level of education of dispatchers. CONCLUSION: The sensitivity and specificity of cardiac arrest recognition at the time of emergency call varied across dispatch centres and did not appear to differ by dispatch algorithm/criteria used or education of the dispatcher, although comparisons were hampered by heterogeneity across studies. Future efforts should focus on ways to improve sensitivity of cardiac arrest recognition to optimize patient care and ensure appropriate and timely resource utilization.

Extracorporeal Cardiopulmonary Resuscitation for Refractory Out-of-Hospital Cardiac Arrest: The State of the Evidence and Framework for Application.

Out-of-hospital cardiac arrest (OHCA) affects 134 per 100,000 citizens annually. Extracorporeal cardiopulmonary resuscitation (ECPR), providing mechanical circulatory support, may improve the likelihood of survival among those with refractory OHCA. Compared with in-hospital ECPR candidates, those in the out-of-hospital setting tend to be sudden unexpected arrests in younger and healthier patients. The aims of this review were to summarize, and identify the limitations of, the evidence evaluating ECPR for OHCA, and to provide an approach for ECPR program application. Although there are many descriptions of ECPR-treated cohorts, we identified a paucity of robust data showing ECPR effectiveness compared with conventional resuscitation. However, it is highly likely that ECPR, provided after a prolonged attempt with conventional resuscitation, does benefit select patient populations compared with conventional resuscitation alone. Although reliable data showing the optimal patient selection criteria for ECPR are lacking, most implementations sought young previously healthy patients with rapid high-quality cardiopulmonary resuscitation. Carefully planned development of ECPR programs, in high-performing emergency medical systems at experienced extracorporeal membrane oxygenation centres, may be reasonable as part of systematic efforts to determine ECPR effectiveness and globally improve care. Protocol evaluation requires regional-level assessment, examining the incremental benefit of survival compared with standard care, while accounting for resource utilization.

Antimicrobial growth promoter use in livestock: a requirement to understand their modes of action to develop effective alternatives.

Antimicrobial agents (AMAs) have been used in agriculture since the 1950s as growth-promoting agents [antimicrobial growth promoters (AGPs)]. They have provided benefits to the agricultural industry by increasing production efficiencies and maximising livestock health, yet the potential risks surrounding resistance to AMAs in medically important pathogenic bacteria have enhanced public and government scrutiny regarding AMA use in agriculture. Although it is recognised that AGP administration can select for resistance to AMAs in enteric bacteria of livestock, conclusive evidence showing a link between resistant bacteria from livestock and human health is lacking (e.g. transmission of resistant zoonotic pathogens). Livestock production output must be increased significantly due to the increase in global population, and thus the identification of non-AMA alternatives to AGP use is required. One strategy employed to identify alternatives to AGPs is an observational empirical methodology, but this approach has failed to deliver effective alternatives. A second approach is aimed at understanding the mechanisms involved in AGP function and developing alternatives that mimic the physiological responses to AGPs. New evidence indicates that AGP function is more complex than merely affecting enteric bacterial populations, and AGPs likely function by directly or indirectly modulating host responses such as the immune system. As such, a more comprehensive understanding of the mechanisms associated with AMA function as AGPs will facilitate the development of effective alternatives.

Endoscopy versus imaging: Analysis of surveillance methods in sinonasal malignancy.

BACKGROUND: The purpose of this study was to assess the utility of imaging and endoscopy in posttreatment surveillance of sinonasal malignancies. METHODS: We conducted a retrospective analysis of primary sinonasal malignancies diagnosed between 2000 and 2014. Posttreatment surveillance included nasal endoscopy and imaging (MRI, CT, and positron emission tomography [PET]/CT). Positive predictive value (PPV), negative predictive value (NPV), specificity, and sensitivity were calculated for each modality and compared. RESULTS: One hundred nine sinonasal malignancies were identified with 30 recurrences. Endoscopy showed a sensitivity and specificity of 24% and 89%, respectively, whereas imaging was 76% and 90%, respectively. Identifying suspicious symptoms significantly improved the PPV of both endoscopy and imaging. MRI demonstrates the highest PPV when compared with other imaging modalities. CONCLUSION: Both modalities are necessary in posttreatment surveillance. MRI shows the highest PPV, whereas endoscopy trends toward a higher specificity. PET/CT scans have a high false-positive rate and should be reserved for tumors with a high propensity for distant metastases. © 2016 Wiley Periodicals, Inc. Head Neck 38:1229-1233, 2016.

The estimation of calibration equations for variables with heteroscedastic measurement errors.

In clinical chemistry and medical research, there is often a need to calibrate the values obtained from an old or discontinued laboratory procedure to the values obtained from a new or currently used laboratory method. The objective of the calibration study is to identify a transformation that can be used to convert the test values of one laboratory measurement procedure into the values that would be obtained using another measurement procedure. However, in the presence of heteroscedastic measurement error, there is no good statistical method available for estimating the transformation. In this paper, we propose a set of statistical methods for a calibration study when the magnitude of the measurement error is proportional to the underlying true level. The corresponding sample size estimation method for conducting a calibration study is discussed as well. The proposed new method is theoretically justified and evaluated for its finite sample properties via an extensive numerical study. Two examples based on real data are used to illustrate the procedure.

Estimation of the effects of rounding visual acuity data.

AIMS: To examine the effect of rounding of visual acuity data on estimates of surgical performance. METHOD: In this observational study, the distribution of 1-year Snellen visual acuity data from 606 endothelial keratoplasties from the NHSBT UK transplant database was analysed. A curve was fitted to the data and used to estimate the frequencies of partly read Snellen lines. The estimates were used to create a virtual database of grafts with Snellen acuities that included individual letter scores. The virtual database was then sampled to produce datasets for 10 virtual surgeons. Various acuity analysis methods were then applied to simulate possible effects of surgeons rounding their data. RESULTS: Rounding of acuity data was found to have a notable effect on estimates of surgeons' success rates. When a criterion of 6/12 or better was applied, the success rates ranged from 62% to 80% using a conservative method of estimation but ranged from 80% to 94% using a less conservative method. CONCLUSIONS: Rounding of visual acuity scores is an important potential bias in outcome data and should be avoided. If rounding is required we recommend that it is carried out conservatively, giving credit only for lines read completely.

Cardiopulmonary resuscitation and automatic external defibrillator training in schools: "is anyone learning how to save a life?".

OBJECTIVES: Bystander resuscitation efforts, such as cardiopulmonary resuscitation (CPR) and use of an automatic external defibrillator (AED), save lives in cardiac arrest cases. School training in CPR and AED use may increase the currently low community rates of bystander resuscitation. The study objective was to determine the rates of CPR and AED training in Toronto secondary schools and to identify barriers to training and training techniques. METHODS: This prospective study consisted of telephone interviews conducted with key school staff knowledgeable about CPR and AED teaching. An encrypted Web-based tool with prespecified variables and built-in logic was employed to standardize data collection. RESULTS: Of 268 schools contacted, 93% were available for interview and 83% consented to participate. Students and staff were trained in CPR in 51% and 80% of schools, respectively. Private schools had the lowest training rate (39%). Six percent of schools provided AED training to students and 47% provided AED training to staff. Forty-eight percent of schools had at least one AED installed, but 25% were unaware if their AED was registered with emergency services dispatch. Cost (17%), perceived need (11%), and school population size (10%) were common barriers to student training. Frequently employed training techniques were interactive (32%), didactic instruction (30%) and printed material (16%). CONCLUSIONS: CPR training rates for staff and students were moderate overall and lowest in private schools, whereas training rates in AED use were poor in all schools. Identified barriers to training include cost and student population size (perceived to be too small to be cost-effective or too large to be implemented). Future studies should assess the application of convenient and cost-effective teaching alternatives not presently in use.

Dry deposition of gaseous oxidized mercury in Western Maryland.

The purpose of this study was to directly measure the dry deposition of gaseous oxidized mercury (GOM) in western Maryland. Annual estimates were made using passive ion-exchange surrogate surfaces and a resistance model. Surrogate surfaces were deployed for seventeen weekly sampling periods between September 2009 and October 2010. Dry deposition rates from surrogate surfaces ranged from 80 to 1512 pgm(-2)h(-1). GOM dry deposition rates were strongly correlated (r(2)=0.75) with the weekly average atmospheric GOM concentrations, which ranged from 2.3 to 34.1 pgm(-3). Dry deposition of GOM could be predicted from the ambient air concentrations of GOM using this equation: GOM dry deposition (pgm(-2)h(-1))=43.2 × GOM concentration-80.3. Dry deposition velocities computed using GOM concentrations and surrogate surface GOM dry deposition rates, ranged from 0.2 to 1.7 cms(-1). Modeled dry deposition rates were highly correlated (r(2)=0.80) with surrogate surface dry deposition rates. Using the overall weekly average surrogate surface dry deposition rate (369 ± 340 pg m(-2)h(-1)), we estimated an annual GOM dry deposition rate of 3.2 µg m(-2)year(-1). Using the resistance model, we estimated an annual GOM dry deposition rate of 3.5 µg m(-2)year(-1). Our annual GOM dry deposition rates were similar to the dry deposition (3.3 µg m(-2)h(-1)) of gaseous elemental mercury (GEM) at our site. In addition, annual GOM dry deposition was approximately 1/2 of the average annual wet deposition of total mercury (7.7 ± 1.9 µg m(-2)year(-1)) at our site. Total annual mercury deposition from dry deposition of GOM and GEM and wet deposition was approximately 14.4 µg m(-2)year(-1), which was similar to the average annual litterfall deposition (15 ± 2.1 µg m(-2)year(-1)) of mercury, which was also measured at our site.

A knowledge translation collaborative to improve the use of therapeutic hypothermia in post-cardiac arrest patients: protocol for a stepped wedge randomized trial.

BACKGROUND: Advances in resuscitation science have dramatically improved survival rates following cardiac arrest. However, about 60% of adults that regain spontaneous circulation die before leaving the hospital. Recently it has been shown that inducing hypothermia in cardiac arrest survivors immediately following their arrival in hospital can dramatically improve both overall survival and neurological outcomes. Despite the strong evidence for its efficacy and the apparent simplicity of this intervention, recent surveys show that therapeutic hypothermia is delivered inconsistently, incompletely, and often with delay. METHODS AND DESIGN: This study will evaluate a multi-faceted knowledge translation strategy designed to increase the utilization rate of induced hypothermia in survivors of cardiac arrest across a network of 37 hospitals in Southwestern Ontario, Canada. The study is designed as a stepped wedge randomized trial lasting two years. Individual hospitals will be randomly assigned to four different wedges that will receive the active knowledge translation strategy according to a sequential rollout over a number of time periods. By the end of the study, all hospitals will have received the intervention. The primary aim is to measure the effectiveness of a multifaceted knowledge translation plan involving education, reminders, and audit-feedback for improving the use of induced hypothermia in survivors of cardiac arrest presenting to the emergency department. The primary outcome is the proportion of eligible OHCA patients that are cooled to a body temperature of 32 to 34°C within six hours of arrival in the hospital. Secondary outcomes will include process of care measures and clinical outcomes. DISCUSSION: Inducing hypothermia in cardiac arrest survivors immediately following their arrival to hospital has been shown to dramatically improve both overall survival and neurological outcomes. However, this lifesaving treatment is frequently not applied in practice. If this trial is positive, our results will have broad implications by showing that a knowledge translation strategy shared across a collaborative network of hospitals can increase the number of patients that receive this lifesaving intervention in a timely manner. TRIAL REGISTRATION: ClinicalTrials.gov Trial Identifier: NCT00683683.

A Bayesian approach to phylogeographic clustering.

Phylogeographic methods have attracted a lot of attention in recent years, stressing the need to provide a solid statistical framework for many existing methodologies so as to draw statistically reliable inferences. Here, we take a flexible fully Bayesian approach by reducing the problem to a clustering framework, whereby the population distribution can be explained by a set of migrations, forming geographically stable population clusters. These clusters are such that they are consistent with a fixed number of migrations on the corresponding (unknown) subdivided coalescent tree. Our methods rely upon a clustered population distribution, and allow for inclusion of various covariates (such as phenotype or climate information) at little additional computational cost. We illustrate our methods with an example from weevil mitochondrial DNA sequences from the Iberian peninsula.

On smoothing trends in population index modeling.

In this article, we consider the U.K. Common Birds Census counts and their use in monitoring bird abundance. We use a state-space modeling approach within a Bayesian framework to describe population level trends over time and contribute to the alert system used by the British Trust for Ornithology. We account for potential overdispersion and excess zero counts by modeling the observation process with a zero-inflated negative binomial, while the system process is described by second-order polynomial growth models. In order to provide a biological motivation for the amount of smoothing applied to the observed series the system variance is related to the demographic characteristics of the species, so as to help the specification of its prior distribution. In particular, the available information on productivity and survival is used to formulate prior expectations on annual percentage changes in the population level and then used to constrain the variance of the system process. We discuss an example of how to interpret alternative choices for the degree of smoothing and how these relate to the classification of species, over time, into conservation lists.

The effect of methylprednisolone on warm ischemia-reperfusion injury in the liver.

BACKGROUND: Liver ischemia-reperfusion (I-R) injury is a well-known cause of morbidity and mortality following liver surgery and transplantation. Further investigation is warranted to identify measures that reduce the untoward sequelae of liver ischemia. METHODS: Male Sprague-Dawley rats (wild-type) and Zucker rats (with hepatic steatosis) were subjected to 75 minutes of 70% hepatic ischemia and 3 hours of reperfusion. The ischemic periods were based on protocols of either continuous clamping (CC) or ischemic preconditioning (IP). Prior to ischemia induction, rats were pretreated with intravenous methylprednisolone (MP; 2 mg/kg) or normal saline. Warm I-R injury was evaluated using serum levels of aspartate aminotransferase (AST), serum interleukin-6 (IL-6), and hematoxylin and eosin staining. RESULTS: Histology, serum IL-6, and AST release revealed that MP treatment provided significant protection as compared with ischemic controls (both CC and IP groups) only in the normal, not steatotic, livers. The inflammatory response was considerably reduced in MP groups with normal livers but not in steatotic livers. In general, the IP groups showed decreased I-R injury compared to the CC group. However, MP was able to further reduce I-R injury only in normal, not steatotic, livers. CONCLUSIONS: MP attenuated the postischemic and inflammatory response in the normal, and not steatotic, livers. MP pretreatment might be effective in reducing warm I-R injury to livers without steatosis. The mechanism of I-R-related hepatocellular damage in steatotic liver is different than in normal liver.

Cutting Edge: Lentiviral short hairpin RNA silencing of PTEN in human mast cells reveals constitutive signals that promote cytokine secretion and cell survival.

Engagement of the FcepsilonRI expressed on mast cells induces the production of phosphatidylinositol 3, 4, 5-trisphosphate by PI3K, which is essential for the functions of the cells. PTEN (phosphatase and tensin homologue deleted on chromosome ten) directly opposes PI3K by dephosphorylating phosphatidylinositol 3, 4, 5-trisphosphate at the 3' position. In this work we used a lentivirus-mediated short hairpin RNA gene knockdown method to study the role of PTEN in CD34(+) peripheral blood-derived human mast cells. Loss of PTEN caused constitutive phosphorylation of Akt, p38 MAPK, and JNK, as well as cytokine production and enhancement in cell survival, but not degranulation. FcepsilonRI engagement of PTEN-deficient cells augmented signaling downstream of Src kinases and increased calcium flux, degranulation, and further enhanced cytokine production. PTEN-deficient cells, but not control cells, were resistant to inhibition of cytokine production by wortmannin, a PI3K inhibitor. The findings demonstrate that PTEN functions as a key regulator of mast cell homeostasis and FcepsilonRI-responsiveness.

Prior information in behavioral capture-recapture methods: demographic influences on drug injectors' propensity to be listed in data sources and their drug-related mortality.

The authors present findings from a Bayesian analysis of Scotland's four primary capture-recapture data sources for 2000 that was carried out to estimate numbers of current injecting drug users by region (Greater Glasgow vs. elsewhere in Scotland), sex (male vs. female), and age group (15-34 years vs. > or =35 years). A secondary goal of the analysis was to obtain Bayesian estimates and credible intervals for the demographic influences on Scotland's drug-related death rate per 100 current injectors. Incorporation of informative priors altered the models with highest posterior probability. Expert opinion on how demography influenced Scottish drug injectors' propensity to be listed in different data sources was taken into account, along with external information about European injectors' drug-related death rates and male:female ratios. Higher drug-related mortality was confirmed in older drug injectors and those outside of Greater Glasgow. Female injectors' lower drug-related death rate was not sustained beyond 34 years of age. The authors recommend that demographic influences be accommodated in behavioral capture-recapture estimation, especially when it is a prelude to secondary analysis, such as the analysis of drug-related death rates presented here.

Dynamic oxidation of gaseous mercury in the Arctic troposphere at polar sunrise.

Gaseous elemental mercury (Hg0) is a globally distributed air toxin with a long atmospheric residence time. Any process that reduces its atmospheric lifetime increases its potential accumulation in the biosphere. Our data from Barrow, AK, at 71 degrees N show that rapid, photochemically driven oxidation of boundary-layer Hg0 after polar sunrise, probably by reactive halogens, creates a rapidly depositing species of oxidized gaseous mercury in the remote Arctic troposphere at concentrations in excess of 900 pg m(-3). This mercury accumulates in the snowpack during polar spring at an accelerated rate in a form that is bioavailable to bacteria and is released with snowmelt during the summer emergence of the Arctic ecosystem. Evidence suggests that this is a recent phenomenon that may be occurring throughout the earth's polar regions.

A scaling approach for quantifying the net CO2 flux of the Kuparuk River Basin, Alaska.

Net CO2 flux measurements conducted during the summer and winter of 1994-96 were scaled in space and time to provide estimates of net CO2 exchange during the 1995-96 (9 May 1995-8 May 1996) annual cycle for the Kuparuk River Basin, a 9200 km2 watershed located in NE Alaska. Net CO2 flux was measured using dynamic chambers and eddy covariance in moist-acidic, nonacidic, wet-sedge, and shrub tundra, which comprise 95% of the terrestrial landscape of the Kuparuk Basin. CO2 flux data were used as input to multivariate models that calculated instantaneous and daily rates of gross primary production (GPP) and whole-ecosystem respiration (R) as a function of meteorology and ecosystem development. Net CO2 flux was scaled up to the Kuparuk Basin using a geographical information system (GIS) consisting of a vegetation map, digital terrain map, dynamic temperature and radiation fields, and the models of GPP and R. Basin-wide estimates of net CO2 exchange for the summer growing season (9 May-5 September 1995) indicate that nonacidic tundra was a net sink of -31.7 ± 21.3 GgC (1 Gg = 109 g), while shrub tundra lost 32.5 ± 6.3 GgC to the atmosphere (negative values denote net ecosystem CO2 uptake). Acidic and wet sedge tundra were in balance, and when integrated for the entire Kuparuk River Basin (including aquatic surfaces), whole basin summer net CO2 exchange was estimated to be in balance (-0.9 ± 50.3 GgC). Autumn to winter (6 September 1995-8 May 1996) estimates of net CO2 flux indicate that acidic, nonacidic, and shrub tundra landforms were all large sources of CO2 to the atmosphere (75.5 ± 8.3, 96.4 ± 11.4, and 43.3 ± 4.7 GgC for acidic, nonacidic, and shrub tundra, respectively). CO2 loss from wet sedge surfaces was not substantially different from zero, but the large losses from the other terrestrial landforms resulted in a whole basin net CO2 loss of 217.2 ± 24.1 GgC during the 1995-96 cold season. When integrated for the 1995-96 annual cycle, acidic (66.4 + 25.25 GgC), nonacidic (64.7 ± 29.2 GgC), and shrub tundra (75.8 ± 8.4 GgC) were substantial net sources of CO2 to the atmosphere, while wet sedge tundra was in balance (0.4 + 0.8 GgC). The Kuparuk River Basin as a whole was estimated to be a net CO2 source of 218.1 ± 60.6 GgC over the 1995-96 annual cycle. Compared to direct measurements of regional net CO2 flux obtained from aircraft-based eddy covariance, the scaling procedure provided realistic estimates of CO2 exchange during the summer growing season. Although winter estimates could not be assessed directly using aircraft measurements of net CO2 exchange, the estimates reported here are comparable to measured values reported in the literature. Thus, we have high confidence in the summer estimates of net CO2 exchange and reasonable confidence in the winter net CO2 flux estimates for terrestrial landforms of the Kuparuk river basin. Although there is larger uncertainty in the aquatic estimates, the small surface area of aquatic surfaces in the Kuparuk river basin (≈ 5%) presumably reduces the potential for this uncertainty to result in large errors in basin-wide CO2 flux estimates.