Clinical review: Tokyo - protecting the health care worker during a chemical mass casualty event: an important issue of continuing relevance

Optimizing Medical Care during a Nerve Agent Mass Casualty Incident Using Computer Simulation

INTRODUCTION

Chemical mass casualty incidents (MCIs) pose a substantial threat to public health and safety, with the capacity to overwhelm healthcare infrastructure and create societal disorder. Computer simulation systems are becoming an established mechanism to validate these plans due to their versatility, cost-effectiveness and lower susceptibility to ethical problems.

METHODS

We created a computer simulation model of an urban subway sarin attack analogous to the 1995 Tokyo sarin incident. We created and combined evacuation, dispersion and victim models with the SIMEDIS computer simulator. We analyzed the effect of several possible approaches such as evacuation policy ('Scoop and Run' vs. 'Stay and Play'), three strategies (on-site decontamination and stabilization, off-site decontamination and stabilization, and on-site stabilization with off-site decontamination), preliminary triage, victim distribution methods, transport supervision skill level, and the effect of search and rescue capacity.

RESULTS

Only evacuation policy, strategy and preliminary triage show significant effects on mortality. The total average mortality ranges from 14.7 deaths in the combination of off-site decontamination and Scoop and Run policy with pretriage, to 24 in the combination of onsite decontamination with the Stay and Play and no pretriage.

CONCLUSION

Our findings suggest that in a simulated urban chemical MCI, a Stay and Play approach with on-site decontamination will lead to worse outcomes than a Scoop and Run approach with hospital-based decontamination. Quick transport of victims in combination with on-site antidote administration has the potential to save the most lives, due to faster hospital arrival for definitive care.

Creating realistic nerve agent victim profiles for computer simulation of medical CBRN disaster response

In the last decades, Chemical, Biological, Radiological and Nuclear (CBRN) threats have become serious risks prompting countries to prioritize preparedness for such incidents. As CBRN scenarios are very difficult and expensive to recreate in real life, computer simulation is particularly suited for assessing the effectiveness of contingency plans and identifying areas of improvement. These computer simulation exercises require realistic and dynamic victim profiles, which are unavailable in a civilian context. In this paper we present a set of civilian nerve agent injury profiles consisting of clinical parameters and their evolution, as well as the methodology used to create them. These injury profiles are based on military injury profiles and adapted to the civilian population, using sarin for the purpose of illustration. They include commonly measured parameters in the prehospital setting. We demonstrate that information found in military sources can easily be adjusted for a civilian population using a few simple assumptions and validated methods. This methodology can easily be expanded to other chemical warfare agents as well as different ways of exposure. The resulting injury profiles are generic so they can also be used in tabletop and live simulation exercises. Modeling and simulation, if used correctly and in conjunction with empirical data gathered from lessons learned, can assist in providing the evidence practices for effective and efficient response decisions and interventions, considering the contextual factors of the affected area and the specific disaster scenario.

Ultrafine Silver Nanoparticle Encapsulated Porous Molecular Traps for Discriminative Photoelectrochemical Detection of Mustard Gas Simulants by Synergistic Size-Exclusion and Site-Specific Recognition

The rapid, discriminative, and portable detection of highly toxic chemical warfare agents is extremely important for response to public security emergencies but remains a challenge. One plausible solution involves the integration of porous molecular traps onto a photoelectrochemical (PEC) sensor. Here, a fast and facile protocol is developed to fabricate sub-1 nm AgNPs encapsulated hydrogen-bonded organic framework (HOF) nanocomposite materials through an in situ photoreduction and subsequent encapsulation process. Compared to traditional semiconductors and selected metal-organic frameworks (MOF) materials, these AgNPs@HOFs show significantly enhanced photocurrent. Most importantly, the portable PEC device based on AgNPs@HOF-101 can selectively recognize 13 different mustard gas simulants, including 2-chloroethyl ethyl sulfide (CEES), based on synergistic size-exclusion and specific recognition. The extremely low detection limit for CEES (15.8 nmol L^-1 ), reusability (at least 30 cycles), and long-term working stability (at least 30 d) of the portable PEC device warrant its use as a chemical warfare agents (CWAs) sensor in practical field settings. More broadly, this work indicates that integrating porous molecular traps onto PEC sensors offers a promising strategy to further develop portable devices for CWAs detection with both ultrahigh sensitivity and selectivity.

Safety and Efficacy of CarbonCool Half-Body Vest for HAZMAT Decontamination Crews Wearing Personal Protective Equipment: A Pilot Study

BACKGROUND

Personal protective equipment (PPE) are essential for medical personnel responding to hazardous materials (HAZMAT) incidents. However, their impermeable design causes increased physiological strain and reduced thermoregulation, limiting work times and causing heat-related illnesses (HRI). Use of wearable cooling devices slow heat accumulation and have been shown to reduce thermal and cardiovascular strain in such situations.

METHODS

This was a prospective clinical evaluation to determine the tolerability and effectiveness of the CarbonCool cooling system - a half-body cooling vest - in participants undergoing a HAZMAT decontamination recertification. Physiological measurements (heart rate [HR], weight, temperature, and blood pressure) and participant feedback were obtained. The main outcome of interest was participants' tolerability of the cooling vest.

RESULTS

A total of 23 healthy participants were recruited, with 10 randomized to the intervention group and 13 in the control group. Mean age in the control and intervention group was 35.5 years old (SD = 7.8) and 30.0 years old (SD = 6.2), respectively. Qualitative feedback obtained from participants regarding safety, mobility, and cooling efficacy was largely positive. Difference of before-after temperature and HR was 0.3°C (SD = 0.8) and 11.5bpm (SD = 13.6) in the control group compared to 0.0°C (SD = 0.5) and 0.0bpm (SD = 6.4) for the intervention group.

CONCLUSION

This clinical evaluation showed that the CarbonCool cooling vest is safe and tolerable in participants wearing PPE. Further trials with sample size powered to detect physiological outcomes are needed to assess the effect of the cooling vest on a subject's endurance to heat stress.

Detection of Chemical Warfare Agents by Colorimetric Sensor Arrays

We report the successful use of colorimetric arrays to identify chemical warfare agents (CWAs). Methods were developed to interpret and analyze a 73-indicator array with an entirely automated workflow. Using a cross-validated first-nearest-neighbor algorithm for assessing detection and identification performances on 632 exposures, at 30 min postexposure we report, on average, 78% correct chemical identification, 86% correct class-level identification, and 96% correct red light/green light (agent versus non-agent) detection. Of 174 total independent agent test exposures, 164 were correctly identified from a 30 min exposure in the red light/green light context, yielding a 94% correct identification of CWAs. Of 149 independent non-agent exposures, 139 were correctly identified at 30 min in the red light/green light context, yielding a 7% false alarm rate. We find that this is a promising approach for the development of a miniaturized, field-portable analytical equipment suitable for soldiers and first responders.

Review of Biomarkers and Analytical Methods for Organophosphate Pesticides and Applicability to Nerve Agents

Introduction

Recent malicious use of chemical warfare agents (CWAs) is a reminder of their severity and ongoing threat. One of the main categories of CWAs is the organophosphate (OP) nerve agents. Presently, there is an urgent need to identify and evaluate OP nerve agent biomarkers that can facilitate identification of exposed individuals post-CWA incident. While exposures to OP nerve agents may be scenario-specific, the public is commonly exposed to OP compounds through the ubiquitous use of OP pesticides, which are chemically related to nerve agents. Therefore, a systematic literature review and methodological quality assessment were conducted for OP pesticide biomarker studies to serve as a baseline to assess if these approaches may be adapted to OP nerve agent exposures.

Materials and Methods

We conducted a systematic literature review to identify biomarkers of OP pesticide exposures. English language studies of any design that reported primary data on biomarkers for exposures in nonhuman primates or adult human study participants were eligible for inclusion. Using standard criteria for assessing the completeness of reported analytical methods, the quality of study methods was critically evaluated.

Results

A total of 1,044 studies of biomarkers of OP pesticide exposure were identified, of which 75 articles satisfied the inclusion and exclusion criteria. These studies described 143 different analyte/sample matrix combinations: 99 host-based biomarkers, 28 metabolites, 12 pesticides, and 4 adducts. The most commonly reported biomarkers were dialkyl phosphate urinary metabolites (22 studies), blood acetylcholinesterase, and plasma butyrylcholinesterase (26 studies each). None of the assessed quality review criteria were fully addressed by all identified studies, with almost all criteria scoring less than 50%.

Conclusion

Cholinesterase activity may have utility for identifying individuals with exposures surpassing a given threshold of OP nerve agent, but further investigation of how acetylcholinesterase and butyrylcholinesterase levels correlate with observed patient symptoms may be required to ensure accuracy of results. As CWAs and nerve agents are more readily used, more standardized reporting of biomarker measurements are needed to develop new approaches for OP nerve agent biomarkers.

[Chemical warfare agent poisoning]

Despite long-lasting international efforts to ban and disarm chemical warfare agents (CWAs), they pose an ongoing threat to the population. The reasons for this are existing remainders, inappropriately disposed of chemical munitions and availability of instructions for synthesis in open literature. Dissemination of CWAs during war, warlike conflicts and terrorist incidents has recently resulted in thousands of deaths. In this manuscript CWAs and comparable substances are presented and the signs and symptoms of poisoning with these substances are described. Aside from clear recommendations for the treatment of poisoning by the single groups of CWAs, parallels to well-known related poisonings including pathophysiological similarities are demonstrated. Moreover, aspects of detection, diagnosis and general management, such as decontamination, verification and antidote stockpiling, are described.According to the respective pathophysiological target, CWAs are classified as lung, skin, nerve and incapacitating agents. They are generally liquids at ambient room temperature and are more or less able to vaporise. In recent years, pharmaceutical-based agents (PBAs) came on board although they are not listed in the chemical warfare convention and therefore not listed as CWAs. Due to their high toxicity, however, they are mentioned here. PBAs comprise, for example, synthetic opioids which can act after inhalative respiration.During the rescue of affected victims, early detection of CWAs, restriction of access to the contaminated area and use of protective clothes and masks by first responders are necessary. Exposure should be terminated as soon as possible by removal of the victim from the hot zone and decontamination. The latter is also important to avoid secondary contamination of other persons or facilities located outside of the contaminated zone. According to the type of poisoning, therapy should be started as soon as possible.

A Hazardous Materials Educational Curriculum Improves Pediatric Emergency Department Staff Skills

OBJECTIVE

Emergency department (ED) providers require competency in responding to hazardous materials (HAZMAT) events. The optimal strategies to teach HAZMAT response principles to ED providers and to ensure skill retention are not known. Our aim was to design, implement, and evaluate a multifaceted, interprofessional educational curriculum for pediatric ED staff to improve their skills, knowledge, and confidence in responding to a HAZMAT event.

METHODS

In this longitudinal cohort study, we created and assessed a 3-hour educational curriculum comprised of didactics, skills stations, a tabletop exercise, and a simulated multivictim disaster. Learning objectives included critical aspects of pediatric HAZMAT incident response with an emphasis on donning personal protective equipment (PPE). The primary outcome was the number of HAZMAT PPE donning steps correctly completed within 10 minutes at pre- and postcurriculum assessments measured using a 32-item checklist. Secondary outcomes included skill retention at 3 months, change in knowledge assessed using multiple-choice questions, and change in participant confidence.

RESULTS

Eighty-one of 84 participants (96%) completed the entire curriculum. Compared to the precurriculum assessment, participants completed more donning steps correctly after the intervention (mean increase = 58%, 95% confidence interval [CI] = 48%-70%). Relative to the baseline, more steps were also correctly completed at 3 months (mean increase = 49%, 95% CI = 38%-61%). Performance on multiple-choice knowledge questions and confidence in skills also significantly increased from the pre- to postcurriculum assessments.

CONCLUSIONS

A newly developed HAZMAT educational curriculum improved skills-based performance, knowledge, and confidence in PPE and decontamination skills. Brief, multifaceted educational interventions for ED staff can effectively develop sustainable skills needed for uncommon emergency events.

Secondary Contamination of Medical Personnel, Equipment, and Facilities Resulting From Hazardous Materials Events, 2003–2006

Background: When not managed properly, a hazardous material event can quickly extend beyond the boundaries of the initial release, creating the potential for secondary contamination of medical personnel, equipment, and facilities. Secondary contamination generally occurs when primary victims are not decontaminated or are inadequately decontaminated before receiving medical attention. This article examines the secondary contamination events reported to the Agency for Toxic Substances and Disease Registry (ATSDR) and offers suggestions for preventing such events.

Methods: Data from the ATSDR Hazardous Substances Emergency Events Surveillance system were used to conduct a retrospective analysis of hazardous material events occurring in 17 states during 2003 through 2006 involving secondary contamination of medical personnel, equipment, and facilities.

Results: Fifteen (0.05%) Hazardous Substances Emergency Events Surveillance events were identified in which secondary contamination occurred. At least 17 medical personnel were injured as a result of secondary contamination while they were treating contaminated victims. Of the medical personnel injured, 12 were emergency medical technicians and 5 were hospital personnel. Respiratory irritation was the most common injury sustained.

Conclusions: Adequate preplanning and drills, proper decontamination procedures, good field-to-hospital communication, appropriate use of personal protective equipment, and effective training can help prevent injuries of medical personnel and contamination of transport vehicles and medical facilities. (Disaster Med Public Health Preparedness. 2008;2:104–113)

Mobile decontamination units-room for improvement?

INTRODUCTION

Mobile decontamination units are intended to be used at the accident site to decontaminate persons contaminated by toxic substances. A test program was carried out to evaluate the efficacy of mobile decontamination units.

OBJECTIVE

The tests included functionality, methodology, inside environment, effects of wind direction, and decontamination efficacy.

METHODS

Three different types of units were tested during summer and winter conditions. Up to 15 test-persons per trial were contaminated with the imitation substances Purasolve ethyl lactate (PEL) and methyl salicylate (MES). Decontamination was carried out according to standardized procedures. During the decontamination trials, the concentrations of the substances inside the units were measured. After decontamination, substances evaporating from test-persons and blankets as well as remaining amounts in the units were measured.

RESULTS

The air concentrations of PEL and MES inside the units during decontamination in some cases exceeded short-term exposure limits for most toxic industrial chemicals. This was a problem, especially during harmful wind conditions, i.e., wind blowing in the same direction as persons moving through the decontamination units. Although decontamination removed a greater part of the substances from the skin, the concentrations evaporating from some test-persons occasionally were high and potentially harmful if the substances had been toxic. The study also showed that blankets placed in the units absorbed chemicals and that the units still were contaminated five hours after the end of operations.

CONCLUSIONS

After decontamination, the imitation substances still were present and evaporating from the contaminated persons, blankets, and units. These results indicate a need for improvements in technical solutions, procedures, and training.

TAP CBRN Preparedness: Knowledge, Training and Networks

The main goal of this targeted agenda program (TAP) was the establishment of an international network that would be able to advise on how to improve education and training for chemical, biological, radiological, or nuclear (CBRN)) responders. By combining the members of the TAP group, the CBRN Task Force of the World Association for Disaster and Emergency Medicine (WADEM) and the European network of the Hesculaep Group, an enthusiastic and determined group has been established to achieve the defined goal. It was acknowledged that the bottlenecks for education and training for CBRN responders are mainly awareness and preparedness. For this reason, even basic education and training on CBRN is lacking. It was advised that the focus for the future should be on the development of internationally standardized protocols and standards. The face-to-face discussions of the TAP will be continued at future Hesculaep expert meetings. The intention is that during the 16WCDEM, the achievements of the established network will be presented.

Preparedness lessons from modern disasters and wars

Disasters come in all shapes and forms, and in varying magnitudes and intensities. Nevertheless, they offer many of the same lessons for critical care practitioners and responders. Among these, the most important is that well thought out risk assessment and focused planning are vital. Such assessment and planning require proper training for providers to recognize and treat injury from disaster, while maintaining safety for themselves and others. This article discusses risk assessment and planning in the context of disasters. The article also elaborates on the progress toward the creation of portable, credible, sustainable, and sophisticated critical care outside the walls of an intensive care unit. Finally, the article summarizes yields from military-civilian collaboration in disaster planning and response.

Antidotes for nerve agent poisoning: should we differentiate children from adults?

PURPOSE OF REVIEW

Chemical terrorism presents a threat to the civilian population, including children. Nerve agent antidotes are available in prepackaged autoinjectors that can be delivered rapidly following an exposure. The published evidence on the use of nerve agent antidotes consists of case reports, extrapolation from pediatric organophosphate poisonings, and expert opinion. This review examines the evidence supporting the use of nerve agent antidotes in children.

RECENT FINDINGS

The use of adult formulated atropine and pralidoxime autoinjectors will deliver doses above current recommendations for infants and children. Data demonstrate, however, that atropine overdose is generally well tolerated in young children. Children symptomatic of nerve agent poisoning will likely need both supraphysiologic doses and frequent re-dosing of atropine.

SUMMARY

Based on limited data, the Mark 1 autoinjector kit (Meridian Medical Technologies, Columbia, Maryland, USA) appears to be the most efficacious antidote delivery system following a nerve agent attack. Symptomatic children under 1 year of age should be given a full atropine dose from the Atropen (Meridian Medical Technologies) (0.5 mg) or Mark 1 kits (2 mg), while children over 1 year of age should be given a full dose of both atropine and pralidoxime from the Mark 1 kit when more accurate weight-based dosing of antidotes is impossible.