Systematic review and meta-analysis of intravascular temperature management vs. surface cooling in comatose patients resuscitated from cardiac arrest.

OBJECTIVE: To systematically review the effectiveness and safety of intravascular temperature management (IVTM) vs. surface cooling methods (SCM) for induced hypothermia (IH). METHODS: Systematic review and meta-analysis. English-language PubMed, Embase and the Cochrane Database of Systematic Reviews were searched on May 27, 2019. The quality of included observational studies was graded using the Newcastle-Ottawa Quality Assessment tool. The quality of included randomized trials was evaluated using the Cochrane Collaboration's risk of bias tool. Random effects modeling was used to calculate risk differences for each outcome. Statistical heterogeneity and publication bias were assessed using standard methods. ELIGIBILITY: Observational or randomized studies comparing survival and/or neurologic outcomes in adults aged 18 years or greater resuscitated from out-of-hospital cardiac arrest receiving IH via IVTM vs. SCM were eligible for inclusion. RESULTS: In total, 12 studies met inclusion criteria. These enrolled 1573 patients who received IVTM; and 4008 who received SCM. Survival was 55.0% in the IVTM group and 51.2% in the SCM group [pooled risk difference 2% (95% CI -1%, 5%)]. Good neurological outcome was achieved in 40.9% in the IVTM and 29.5% in the surface group [pooled risk difference 5% (95% CI 2%, 8%)]. There was a 6% (95% CI 11%, 2%) lower risk of arrhythmia with use of IVTM and 15% (95% CI 22%, 7%) decreased risk of overcooling with use of IVTM vs. SCM. There was no significant difference in other evaluated adverse events between groups. CONCLUSIONS: IVTM was associated with improved neurological outcomes vs. SCM among survivors resuscitated following cardiac arrest. These results may have implications for care of patients in the emergency department and intensive care settings after resuscitation from cardiac arrest.

Public health surveillance of automated external defibrillators in the USA: protocol for the dynamic automated external defibrillator registry study.

INTRODUCTION: Lay use of automated external defibrillators (AEDs) before the arrival of emergency medical services (EMS) providers on scene increases survival after out-of-hospital cardiac arrest (OHCA). AEDs have been placed in public locations may be not ready for use when needed. We describe a protocol for AED surveillance that tracks these devices through time and space to improve public health, and survival as well as facilitate research. METHODS AND ANALYSIS: Included AEDs are installed in public locations for use by laypersons to treat patients with OHCA before the arrival of EMS providers on scene. Included cases of OHCA are patients evaluated by organised EMS personnel and treated for OHCA. Enrolment of 10 000 AEDs annually will yield precision of 0.4% in the estimate of readiness for use. Enrolment of 2500 patients annually will yield precision of 1.9% in the estimate of survival to hospital discharge. Recruitment began on 21 Mar 2014 and is ongoing. AEDs are found by using multiple methods. Each AED is then tagged with a label which is a unique two-dimensional (2D) matrix code; the 2D matrix code is recorded and the location and status of the AED tracked using a smartphone; these elements are automatically passed via the internet to a secure and confidential database in real time. Whenever the 2D matrix code is rescanned for any non-clinical or clinical use of an AED, the user is queried to answer a finite set of questions about the device status. The primary outcome of any clinical use of an AED is survival to hospital discharge. Results are summarised descriptively. ETHICS AND DISSEMINATION: These activities are conducted under a grant of authority for public health surveillance from the Food and Drug Administration. Results are provided periodically to participating sites and sponsors to improve public health and quality of care.

What change in outcomes after cardiac arrest is necessary to change practice? Results of an international survey.

BACKGROUND: Efficient trials of interventions for patients with out-of-hospital cardiac arrest (OHCA) should have adequate but not excess power to detect a difference in outcomes. The minimum clinically important difference (MCID) is the threshold value in outcomes observed in a trial at which providers should choose to adopt a treatment. There has been limited assessment of MCID for outcomes after OHCA. Therefore, we conducted an international survey of individuals interested in cardiac resuscitation to define the MCID for a range of outcomes after OHCA. METHODS: A brief survey instrument was developed and modified by consensus. Included were open-ended responses. The survey included an illustrative example of a hypothetical randomized study with distributions of outcomes based on those in a public use datafile from a previous trial. Elicited information included the minimum significant difference required in an outcome to change clinical practice. The population of interest was emergency physicians or other practitioners of acute cardiovascular research. RESULTS: Usable responses were obtained from 160 respondents (50% of surveyed) in 46 countries (79% of surveyed). MCIDs tended to increase as baseline outcomes increased. For a population of patients with 25% survival to discharge and 20% favorable neurologic status at discharge, the MCID were median 5 (interquartile range [IQR] 3, 10) percent for survival to discharge; median 5 (IQR 2, 10) percent for favorable neurologic status at discharge, median 4 (IQR 2, 9) days of ICU-free survival and median 4 (IQR 2, 8) days of hospital-free survival. CONCLUSION: Reported MCIDs for outcomes after OHCA vary according to the outcome considered as well as the baseline rate of achieving it. MCIDs of ICU-free survival or hospital-free survival may be useful to accelerate the rate of evidence-based change in resuscitation care.

Neuroprotection in acute brain injury: an up-to-date review.

Neuroprotective strategies that limit secondary tissue loss and/or improve functional outcomes have been identified in multiple animal models of ischemic, hemorrhagic, traumatic and nontraumatic cerebral lesions. However, use of these potential interventions in human randomized controlled studies has generally given disappointing results. In this paper, we summarize the current status in terms of neuroprotective strategies, both in the immediate and later stages of acute brain injury in adults. We also review potential new strategies and highlight areas for future research.

The Physiologically Difficult Airway.

Airway management in critically ill patients involves the identification and management of the potentially difficult airway in order to avoid untoward complications. This focus on difficult airway management has traditionally referred to identifying anatomic characteristics of the patient that make either visualizing the glottic opening or placement of the tracheal tube through the vocal cords difficult. This paper will describe the physiologically difficult airway, in which physiologic derangements of the patient increase the risk of cardiovascular collapse from airway management. The four physiologically difficult airways described include hypoxemia, hypotension, severe metabolic acidosis, and right ventricular failure. The emergency physician should account for these physiologic derangements with airway management in critically ill patients regardless of the predicted anatomic difficulty of the intubation.

A cuff & a clock.

Ischemic conditioning is a unique physiologic process that has shown potential for reducing the size of MI in animal studies for more than twenty years. Early human trials have been inconclusive. However, one clinical trial is in progress that is well designed and will enroll enough subjects to potentially demonstrate significant reductions in mortality and hospitalization for congestive heart failure in STEMI patients who receive RIC in the field. Certainly, the simplicity, low cost and safety of ischemic conditioning merit continued clinical study in humans.

Tunnel vision.

Since 2000, many studies of advanced emergency airway management have appeared in the medical literature. Although most described patients in the operating room, intensive care unit or emergency department, studies of video laryngoscopy in the field are in progress and beginning to appear in the literature. Video laryngoscopy provides better views of the glottis, and it permits more successful intubations with fewer attempts. Price reductions as more devices, some specifically intended for EMS, enter the market will lower the entry costs for adoption. It is my prediction that in five years, video laryngoscopy will be the method of choice for endotracheal intubation in the field.

Telemedicine and telepresence for prehospital and remote hospital tracheal intubation using a GlideScope™ videolaryngoscope: a model for tele-intubation.

BACKGROUND: The inability to secure a patient's airway in the prehospital setting is a major cause of potentially preventable death in the field of trauma and emergency medicine. METHODS: The University of Arizona in Tucson has established two telepresence programs, the Southern Arizona Teletrauma and Telepresence Program and Tucson Emergency Room (ER)-Link for assisting with trauma and emergency medicine patients in remote hospitals and prehospital system. Most recently, we have added videolaryngoscopes to our telepresence programs to assist with patients whose airway is difficult to manage. RESULT: We describe the first reported case of using a videolaryngoscope (GlideScope™) and a telemedicine network to assist a healthcare provider performing tracheal intubation in a remote hospital. CONCLUSION: Videolaryngoscopes allows for assistance with remote tracheal intubation and should be strongly considered as a component of teletrauma and telepresence programs to assist with difficult airway management.

Pediatric defibrillation doses often fail to terminate prolonged out-of-hospital ventricular fibrillation in children.

BACKGROUND: The recommended dose for pediatric defibrillation is 2 J/kg, based on animal studies of brief duration ventricular fibrillation (VF) and a single pediatric study of short duration in-hospital VF. In a piglet model of out-of-hospital (prolonged) cardiac arrest, this recommended dose was usually ineffective at terminating VF. We, therefore, hypothesized that pediatric dose defibrillation may be less effective for prolonged out-of-hospital pediatric VF. METHODS: We evaluated retrospectively all cardiac arrests in children less than 13 years old in Tucson from November 1998 to April 2003, with special attention to all children in ventricular fibrillation. We determined the rate of ventricular fibrillation termination after pediatric dose shocks in this cohort, and compared this rate with a published historical pediatric in-hospital defibrillation control group. A pediatric dose shock was defined as 2 J/kg (+/-10 J). All shocks in both groups were provided as monophasic damped sinusoidal waveforms. RESULTS: Thirteen of 151 (9%) children with out-of-hospital cardiac arrest had documented VF. Eleven children received a total of 14 pediatric dose shocks. The median minimum untreated dispatch-to-shock time in unwitnessed arrest or collapse-to-shock in witnessed arrest for those 11 children was 11 min (interquartile range 25-75%; 9-15.5 min). Seven of the 14 pediatric dose shocks terminated the VF (six to asystole, one to pulseless electrical activity). Nine children (68%) died in the emergency department and four (31%) in the pediatric intensive care unit; none survived to hospital discharge. Failure to terminate VF after a pediatric dose shock in this study group with prolonged out-of-hospital ventricular fibrillation was substantially more common than the previously reported in-hospital data (7/14 versus 5/57; OR 10.4; 95% CI 2.6-42; P=0.001). CONCLUSIONS: Termination of VF after a pediatric defibrillation dose is substantially worse for prolonged pediatric out-of-hospital VF cardiac arrest compared with in-hospital (short duration) ventricular fibrillation. The optimal pediatric defibrillation dose for prolonged VF is not known.

Interruptions of chest compressions during emergency medical systems resuscitation.

BACKGROUND: Survival after nontraumatic out-of-hospital (OOH) cardiac arrest in Tucson, Arizona, has been flat at 6% (121/2177) for the decade 1992 to 2001. We hypothesized that interruptions of chest compressions occur commonly and for substantial periods during treatment of OOH cardiac arrest and could be contributing to the lack of improvement in resuscitation outcome. METHODS AND RESULTS: Sixty-one adult OOH cardiac arrest patients treated by automated external defibrillator (AED)-equipped Tucson Fire Department first responders from November 2001 through November 2002 were retrospectively reviewed. Reviews were performed according to the code arrest record and verified with the AED printout. Validation of the methodology for determining the performance of chest compressions was done post hoc. The median time from "9-1-1" call receipt to arrival at the patient's side was 6 minutes, 27 seconds (interquartile range [IQR, 25% to 75%], 5 minutes, 24 seconds, to 7 minutes, 34 seconds). An additional 54 seconds (IQR, 38 to 74 seconds) was noted between arrival and the first defibrillation attempt. Initial defibrillation shocks never restored a perfusing rhythm (0/21). Chest compressions were performed only 43% of the time during the resuscitation effort. Although attempting to follow the 2000 guidelines for cardiopulmonary resuscitation, chest compressions were delayed or interrupted repeatedly throughout the resuscitation effort. Survival to hospital discharge was 7%, not different from that of our historical control (4/61 versus 121/2177; P=0.74). CONCLUSIONS: Frequent interruption of chest compressions results in no circulatory support during more than half of resuscitation efforts. Such interruptions could be a major contributing factor to the continued poor outcome seen with OOH cardiac arrest.

An alternative approach to advancing resuscitation science.

Stagnant survival rates in out-of-hospital cardiac arrest remain a great impetus for advancing resuscitation science. International resuscitation guidelines, with all their advantages for standardizing resuscitation therapeutic protocols, can be difficult to change. A formalized evidence-based process has been adopted by the International Liason Committee on Resuscitation (ILCOR) in formulating such guidelines. Currently, randomized clinical trials are considered optimal evidence, and very few major changes in the Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care are made without such. An alternative approach is to allow externally controlled clinical trials more weight in Guideline formulation and resuscitation protocol adoption. In Tucson, Arizona (USA), the Fire Department cardiac arrest database has revealed a number of resuscitation issues. These include a poor bystander CPR rate, a lack of response to initial defibrillation after prolonged ventricular fibrillation, and substantial time without chest compressions during the resuscitation effort. A local change in our previous resuscitation protocols had been instituted based upon this historical database information.

Post-shock chest compression delays with automated external defibrillator use.

PRIMARY OBJECTIVE: In a swine model of out-of-hospital ventricular fibrillation (VF) cardiac arrest, we established that automated external defibrillator (AED) defibrillation could worsen outcome from prolonged VF compared with manual defibrillation. Worse outcomes were due to substantial interruptions and delays in chest compressions for AED rhythm analyses and shock advice. In particular, the mean interval from first AED shock to first post-shock compressions was 46+/-6s. We hypothesized that the delay from shock to provision of chest compressions is similar in the out-of-hospital setting. MATERIALS AND METHODS: We conducted a retrospective observational review of AED-treated adult VF cardiac arrest victims over a 26-month period to determine the interval from the first AED defibrillation attempt to the initial provision of post-shock chest compressions for out-of-hospital VF cardiac arrests. A two-tiered, single emergency medical service (EMS) system with AED-equipped first responders serves our area of 400 km2 with a population of 487,000 people. The defibrillators record a detailed sequence of events during the resuscitation effort that includes the electrocardiogram with real clock times and a recording of surrounding audible actions. RESULTS: A median of 38 s (IQR 15, 61 s) elapsed between the first shock and the initiation of chest compressions. Approximately half of the delay was due to mechanical/electronic factors and the remainder due to human factors. Of 64 adults in VF, 45 (70%) died before hospital admission, 19 (30%) survived to admission and 10 (16%) survived to hospital discharge. CONCLUSION: Substantial delays in the provision of post-shock chest compressions are typical in this EMS system with AED-equipped first responders.

Hazardous materials responses in a mid-sized metropolitan area.

OBJECTIVE: To determine the chemicals involved in fire department hazardous materials (hazmat) responses and analyze the concomitant emergency medical services' patient care needs. METHODS: The setting was a mid-sized metropolitan area in the southwestern United States with a population base of 400,000 and an incorporated area of 165 square miles. The authors conducted a retrospective evaluation of all fire department hazmat reports, with associated emergency medical services patient encounter forms, and in-patient hospital records from January 1, 1992, through December 31, 1994. RESULTS: The fire department hazardous materials control team responded to 468 hazmat incidents, involving 62 chemicals. The majority of incidents occurred on city streets, with a mean incident duration of 46 minutes. More than 70% of the responses involved flammable gases or liquids. A total of 32 incidents generated 85 patients, 53% of whom required transport for further evaluation and care. Most patients were exposed to airborne toxicants. Only two patients required hospital admission for carbon monoxide poisoning. CONCLUSION: Most hazmat incidents result in few exposed patients who require emergency medical services care. Most patients were exposed to airborne toxicants and very few required hospitalization. Routine data analysis such as this provides emergency response personnel with the opportunity to evaluate current emergency plans and identify areas where additional training may be necessary.

Rapid process redesign in a university-based emergency department: decreasing waiting time intervals and improving patient satisfaction.

Academic emergency departments are traditionally associated with inefficiency and long waits. The academic medical model presents unique barriers to system changes. Several non-university-based EDs have undertaken process redesign, with significant decreases in patient waiting time intervals. This is the presentation of a rapid process redesign in a university-based ED to reduce waiting time intervals. We present the application of a process-improvement team approach to evaluate and redesign patient flow. As a result of this effort, the median waiting room time interval (triage to patient room) decreased from 31 minutes in January 1998 to 4 minutes in July 1998. ED throughput times also decreased, from 4 hours, 21 minutes in January 1998 to 2 hours, 55 minutes in July 1998. Urgent care waiting room time intervals decreased from 52 minutes to 7 minutes and throughput times from 2 hours, 9 minutes to 1 hour, 10 minutes. Patient satisfaction evaluations by an independent institute demonstrated dramatic improvement and establishment of a new benchmark for academic EDs. Process redesign is possible in a busy, complex, tertiary-care ED, with decreases in waiting time intervals and improvement in patient satisfaction. Major sustained support from top-level hospital administrators and physician leadership are fundamental prerequisites. With these in place, a process improvement team approach for evaluating and redesigning the patient care system can be successful.

Development of New Methods to Assess the Outcomes of Emergency Care.

This article provides information supporting the need for new outcome measures in emergency care. It also addresses the use of outcome measures in emergency care, the impact of emergency care, identification of at-risk groups, new approaches to measuring patient satisfaction, quality of life and cost-effectiveness, and the unique related implications for emergency medicine. [Cairns CB, Garrison HG, Hedges JR, Schriger DL, Valenzuela TD: Development of new methods to assess the outcomes of emergency care. Ann Emerg Med February 1998;31:166-171.].