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The Use of Advanced Simulation in the Training of Anesthesiologists to Treat Chemical Warfare Casualties

Berkenstadt, Haim, MD; Ziv, Amitai, MD; Barsuk, Daphna, MD; Levine, Inbal, RN; Cohen, Amir, MD; Vardi, Amir, MD

doi: 10.1213/01.ANE.0000057027.52664.0B

Training anesthesiologists to treat nerve gas intoxication in a mass casualty scenario is a complicated task. The scenario is an unfamiliar medical situation involving the need to decontaminate patients before providing definitive medical treatment, and the need for physical protection to the medical team before decontamination. We describe the development of a simulation-based training program. In one site of a virtual hospital, anesthesiologists were trained in initial airway and breathing resuscitation before decontamination while wearing full protective gear. In another site, they were trained in the treatment of critically-ill patients with combined conventional and chemical injuries or severe intoxication. Intubation simulators of newborn, pediatric, and adult patients, advanced full-scale simulators, and actors simulating patients were used. Initial airway, breathing, and antidotal treatment were performed successfully, with or without full protective gear. The gas mask did not interfere with orotracheal intubation, but limited effective communication within the medical team. Chemical protective gloves were the limiting factor in the performance of medical tasks such as fixing the orotracheal tube. Twenty-two participants (88%) pointed out that the simulated cases represented realistic problems in this scenario, and all 25 participants found the simulated-based training superior to previous traditional training they had in this field. Using advanced simulation, we were able to train anesthesiologists to treat nerve gas intoxication casualties and to learn about the limitations of providing medical care in this setting.

IMPLICATIONS: Advanced medical simulation can be used to train anesthesiologists to treat nonconventional warfare casualties. The limitations of medical performance in full protective gear can be learned from this training.

Departments of *Anesthesiology and Intensive Care and

†Pediatric Critical Care, and

‡The Israeli Center for Medical Simulation, The Chaim Sheba Medical Center, Tel Hashomer, Israel. Affiliated with the Sackler School of Medicine, Tel Aviv University.

Address correspondence and reprint requests to Haim Berkenstadt, MD, The Department of Anesthesiology and Intensive Care, The Chaim Sheba Medical Center, Tel Hashomer, Israel 52621. Address e-mail to

Accepted January 03, 2003

Exposure to volatile nerve agents during chemical warfare (1,2), or a terrorist attack on civilian population (3), may cause mass casualties. Toxic symptoms are developed over minutes, and are the product of excessive cholinergic discharge presenting as myosis, respiratory, gastrointestinal and dermal hypersecretions, bronchospasm, impairment of the neuromuscular junction, and central nervous system effects. Death is usually related to respiratory failure caused by a combination of bronchospasm, excessive secretions, muscular paralysis, and dysfunction of the respiratory center (4). People near to an explosion site may suffer from both conventional and chemical injuries. The effects of the two types of injuries may be reciprocal, leading to larger difficulties in assessing and treating patients (5).

Under these circumstances, anesthesiologists may have a major role in the treatment of casualties brought to the health services (6). Their role may be mainly in the initial resuscitation and airway management of critically-ill patients before decontamination, treating patients with combined conventional and toxic injuries in the perioperative period, and in treating ventilated patients with severe nerve gas intoxication.

Training anesthesiologists and other members of the medical teams to treat casualties in this situation is complicated because the scenario is one of mass casualties and also because of the unfamiliar medical situation and physical conditions. This includes the need to train in realistic conditions where medical teams are expected to be physically protected from secondary contamination, and to decontaminate patients before providing definitive medical treatment.

The unfortunate political reality has caused the Israeli Health System to establish preparedness programs tailored to nonconventional warfare threats—mainly nerve gas intoxication. Lectures on the medical aspects of intoxication are part of the curriculum of emergency medical technician nursing and medical schools, and medical teams are routinely trained for this task. The traditional training included not only frontal lectures, but also hands-on training with simulated patients undergoing decontamination and simulated treatment while medical personnel were in full protection gear (7). However, traditional drills have always focused more on the logistic aspects of the scenarios and were deficient in providing opportunities for medical teams to actually exercise and practice clinical procedures and the actual management of critically-ill patients.

The developing field of interactive patient simulators has opened new horizons in simulation-based medical training. The availability of these simulators, coupled with the growing need to improve health professional competencies in disaster medicine, have led to the creative use of advanced simulators in chemical warfare training. We describe the first use of advanced simulators in training anesthesiologists as part of multidisciplinary medical teams to manage chemical warfare casualties.

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The training was conducted at the Israeli Center for Medical Simulation. The center is an 800-m2 facility, designed as a virtual hospital, featuring the entire spectrum of medical simulation modalities, including simulated patients, advanced task trainers, and computer-driven, full-body mannequins. Audio-visual equipment ensures effective debriefing and constructive feedback to trainees.

For this training program, the center was organized according to the Israeli protocols of hospital management during chemical warfare conditions. In one site of the virtual hospital, anesthesiologists working in teams with intensive care and postanesthesia care nurses were trained on initial airway and breathing resuscitation to severely injured patients before decontamination. The teams were wearing full protective gear, including a gas mask, chemical protective gloves, and a multilayered overgarment. Teams were instructed to limit the medical treatment to the following: securing of airway by orotracheal intubation, treating patients with specific antidotal automatic injectors, and sending the ventilated patients to decontamination as soon as possible. Teams were instructed not to insert IV lines and, if IV medications were indicated to stop convulsions, to use a Bone Intra-osseous Gun (WaiseMed, Caesarea, Israel) which is a device for the insertion of 15-G intraosseous access. Simple intubation simulators of newborn, pediatric, and adult patients were used after introducing technical changes allowing the simulation of vomiting and oral secretions, that may interfere with airway management. More advanced simulators, such as the Sim-Man (Laerdal Medical, Stavenger, Norway), were used to simulate difficulties in airway and breathing management. Most simulators were brought to the site on stretchers, wearing a gas mask, and without any initial treatment. In some cases “patients” had initial prehospital medical treatment and the anesthesiologists had to reassess previous airway management.

In another site of the virtual hospital, teams of anesthesiologists, surgeons, and nurses were trained in the treatment of critically-ill patients with combined conventional and chemical injuries or severe nerve gas intoxication. Five simulators were used, including the Sim-Man (Laerdal Medical), Air-Man (Laerdal Medical), and the Human Patient Simulator (METI, Gainesville, FL). Scenarios included patients with combined head injury and nerve gas intoxication, combined chest injury and nerve gas intoxication, and patients with isolated severe intoxication.

In two additional sites of the virtual hospital, other teams were trained to treat moderate or mildly intoxicated patients. Simulators, as well as professional actors simulating standardized patients, were used. Anesthesiologists were involved in these sites only on demand, when a patient deteriorated, and airway management was warranted.

The simulative scenarios and the checklists used for performance assessment and feedback were written by a group of experts in anesthesiology, intensive care, and trauma management. All of them had a strong theoretical background in the medical aspects of chemical warfare intoxication. The checklists included essential actions in airway, breathing, and circulation assessment and treatment, and specific antidotal use. Experts in the relevant medical fields from different hospitals in the country, and the relevant experts in the Israeli Defense Forces Medical Corps NBC Branch and the National Health Authorities then reviewed the scenarios and checklists. After having the experts’ opinion, the scenarios and checklists were changed accordingly, and sent to the reviewers for final approval. In the minority of cases, a second round of changes was conducted. During actual training, instructors documented whether essential actions were correctly performed, partially performed, or an action was missing. This checklist information was used as an additional feedback source during the debriefing conducted at the end of each simulated clinical session.

The coordination and communication between individuals in the medical team, and the leadership of the responsible medical director were evaluated subjectively by raters, based on teamwork performance benchmarks such as sense of clinical effectiveness, level and quality of communication among team members, and sense of clear leadership in terms of clinical decision-making and prioritization. Information was used for the debriefing session conducted at the end of each simulated session, and not for a final numerical mark at the end of training.

At the end of training, participants were asked to complete a questionnaire regarding their perception of: 1) realism of the scenarios and the simulated environment, 2) difficulty and challenge of the cases, and 3) the value of simulated training to improve their ability in managing nerve gas intoxication of critical patients. Personnel trained in full protective gear were also asked to give their perception of the ability of a trained anesthesiologist to perform life-saving procedures in this environment, to work as teams, and to identify problems in the equipment and ergonomics of this site.

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All of the anesthesiologists performed initial airway, breathing, and antidotal treatment successfully according to the guidelines in neonate, pediatric, and adult simulators. Performance was according to the accepted standards when anesthesiologists were with or without full protective gear. Moreover, full protective gear including a gas mask did not interfere with anesthesiologists’ ability to recognize and manage one-lung ventilation or blocked orotracheal tube in a neonate, and tension pneumothorax after orotracheal intubation in an adult simulator. According to the participants’ subjective impression, the gas mask did not interfere with orotracheal intubation, but interference with hearing limited effective communication within the medical team. The chemical protective rubber gloves were found to be the limiting factor in the performance of medical tasks. Fixation of the orotracheal tube, preparing of syringes for medication delivery, and opening of the original packages of the medical props were time consuming and challenging. Preparing all the equipment in advance was recommended.

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According to the feedback questionnaires, 22 participants (88%) pointed out that the simulated cases represented realistic problems the anesthesiologist might face while treating critically-ill patients with combined conventional and chemical injuries or severe nerve gas intoxication. The same number reported that the video-based debriefing was excellent or very good. Twenty-three participants claimed that simulator-based training improved their knowledge: 18 reported that the simulator training improved their decision-making, and 22 claimed that it improved their manual skills. All 25 participants found the simulation-based training superior to previous traditional training they had received in treating critically-severe injuries from nerve gas intoxication.

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Advanced medical simulation is used to expose anesthesiologists to critical and relatively rare events during anesthesia, while maintaining patient safety, and maximizing reproducibility and standardization of training (8,9). In the present project, advanced simulation was used to train anaesthesiologists and other members of the medical staff to treat victims of nerve gas intoxication. In this situation, survival of casualties depends on the efficiency and promptness of medical aid in treating both chemical and conventional trauma injuries at the same time (10). The scenarios developed for this project were designed with the aid of experts in toxicology, and most trainees perceived them as authentic and representative of real casualties. However, unlike anesthesia scenarios, based on broad clinical experience, the medical information on nerve gas intoxication is limited, and most information comes from a few reports in the medical literature, data from the terrorist attack in Japan, and information gained from animal studies. Moreover, information on real human combined injuries does not exist in the medical literature. All of the above limit the ability to fully predict and simulate the clinical dynamics of various scenarios.

Medical simulation was used not only for training, but also to assess errors performed by anesthesiologists during critical events in the operating room (11,12). In a similar way, we have used advanced simulation to assess the ability of anesthesiologists to manage immediate airway and breathing emergencies while wearing full protective gear. Medical performance in this situation may be influenced by physiological (13) and/or psychological variables, namely, increased respiratory effort and restricted visual field induced by the gas mask, interference with manual dexterity by the chemical protective gloves (14), and excessive heat load induced by the multilayered overgarment (15). Indeed, previous studies demonstrated that emergency medical technicians’ speed of performance was affected by physical protection (16). In another study (17), no effect of protective gear or the duration of wearing protective gear on success rate or on time needed for successful IV line insertion by emergency medical technicians was demonstrated. In both studies, as in the present study, the effect of gloves on manual dexterity was described as a major limiting factor. In another study, Hendler et al. (18) evaluated the ability of anesthesiologists to manage airway in full protective gear. Intubation duration was prolonged from 47.3 ± 6 seconds without (mean ± SE) to 69.2 ± 7 seconds with full protective gear, and repeated training did not improve performance. In the present study, we did not measure time to completion of orotracheal intubation, but by using technical changes in simple simulators, we were able to induce oral secretions and vomiting without changing success rates of 100%. Moreover, using advanced simulation, we were able to demonstrate the ability of trained anesthesiologists to solve postorotracheal intubation airway problems even in newborn babies while wearing full protective gear. As in the previous study, tube fixation was the rate-limiting factor, mainly in babies, and good alternatives should be sought, especially if patients are transferred for decontamination after the securing of airway.

Although according to the subjective self-evaluation, the simulation-based training improved anesthesiologists’ understanding of the scenario of treating nerve gas casualties, and provided an opportunity to learn about the limitations of performance in this situation, there are some limitations to this training. First, the psychological stress and its effect on medical teams’ performance expected during real nonconventional warfare will exceed the stress experienced during simulative training, and limitations of performance may exceed the findings during simulative training. Another limitation is the cost of training. Training is expensive and will not be available to the hundreds of personnel needed in the hospital during such an event. Training will be available to medical personnel in key positions, such as medical directors of treatment sites, or medical personnel working in special conditions, such as anesthesiologists working in full protective gear. Less expensive computer-based simulators, and videotapes from simulation-based training should be used for the training of other personnel.

The most significant limitation of the training program described is that it was developed to meet an unfortunate urgent national need, and not within a study framework. As a result, objective variables supporting the beneficial effects of training are not available. Pretraining and posttraining tests were not performed, checklists were used mainly to collect information for the debriefing process and not for quantitative performance evaluation, and variables such as interrater agreement are not available. However, as a standardized training program on a national scale, the program has been conducted for multidisciplinary teams from hospitals throughout Israel, and has gained very positive feedback from all trainees. More objective information will be available in a later phase through an analysis of the audio-visual recordings.

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