AIMS AND OBJECTIVES

Incidents involving mass casualties are infrequent. However, they have the potential to overwhelm usual health resources with very little notice. It is therefore important that contingencies are developed, tested and ready for immediate implementation. Such contingencies outline the responsibilities for overall medical control, coordination and effective casualty management in major emergencies and disaster situations. They include the procedures for triage, first aid and resuscitation, some of which require modification when resource availability needs to be rationed.

Response plans must provide a framework for coordination of transporting injured or incident-affected individuals to appropriate treatment sites. Plans must incorporate procedures to enable the presence of medical, nursing and first aid personnel, as well as other welfare personnel and psychological carers, to provide care at the scene of a mass casualty incident.

At a hospital level, plans need to be developed, implemented, rehearsed and evaluated. This enables hospitals that are often full to manage a large number of patients in excess of usual workloads or capacities and, in certain circumstances, victims with special or specific management needs.

Incorporation of public health resources and interventions is integral to provide guidance and procedures where hygiene, sanitation, communicable disease or biological hazards potentially exist. Contingencies must provide an interface for concurrent activation of recovery plans. Access to appropriate and timely psychological support for victims and care providers is included in both early and ongoing recovery phases. The overall objective is to mitigate disasters by participation in event planning and medical and emergency service activation and training.

PHASES OF A DISASTER

The phases of disaster management are prevention, preparedness, response and recovery.

ADMINISTRATIVE AND LEGISLATIVE MANDATES

A national legislative framework for emergency management provides for counter disaster planning for response to and recovery from emergency situations that take place throughout Australia and provides a blue print for state or territory response plans. Separate state emergency recovery plan arrangements, designed to meet long-term assistance to people and communities, are activated during the response phase of an incident to provide early commitment of resources. Specific specialty plans for events such as shore retrieval, major burns management and terrorism have been developed in order to harness a coordinated and cooperative multi-city response.

Very broadly these legislative frameworks provide for:

Accordingly, under these arrangements, the police and the various state or territory emergency service organisations severally develop the non-medical component of the state disaster emergency management plans. Under the various state emergency response arrangements, the health departments have statutory responsibility to provide the necessary planning and response required to deal with matters associated with the general health of the community and to provide medical and hospital services required as a result of a major emergency or disaster.

MEDICAL RESPONSE PLANS AND AGENCIES

A medical response plan (or Medical DISPLAN) provides for a clinical care organisational framework that outlines the roles and responsibilities of the various participating medical and health responders, and provides the necessary integrated procedures for altering and mobilising medical and health personnel, for establishing on-site medical control and for definitive treatment of casualties. The concept is that all arrangements and procedures made within the medical response can be applied from the smallest to the largest incident with a build-up of medical coordination and medical and health resources as necessary, following the general pattern of normal daily operational procedures wherever possible. This extends to contingency planning and has a presence at major events where potential public threat is perceived to exist. Actions can be taken under local aegis in the absence of a declared disaster in order to provide protection from personal liability and to ensure compensation is available for injury to volunteers not covered under other insurance arrangements while training for or participating in emergency response activities.

State medical response plan representation, through medical and health participation in all local, regional and state DISPLAN committees, is mandatory to ensure integrated effective response can be provided in times of emergency.

Pre-hospital medical coordination/disaster scene

Although titles, role delineations, responsibilities, definitions and plans vary amongst the states, the following principles are generic. The descriptions below outline the events and actions that are required for proficient on-site disaster medicine management.

Area medical coordinator (AMC)/senior field emergency medical officer

The area medical coordinator (AMC) is responsible for on-site medical coordination of all medical and health resources required and for the command of all health responders. The AMC is responsible for:

• in conjunction with the ambulance coordinator, establishing an effective medical controlled area (casualty collecting post and medical command post) and effecting liaison with the police coordinator and other emergency services

• providing frequent and accurate assessment of the casualty status to a central medical coordinator usually based at the ambulance communications centre

• assessing the on-site conditions and, if necessary, initiating through the central medical coordinator the setting up of an interim casualty clearing station or designating a triage hospital where transport of injured persons from the scene or local area may incur significant delays

• assessing the requirement for relief of or for further medical teams at the scene, for further first aid support and whether psychological services may be needed.

Central medical coordinator (CMC)

The CMC is usually located in the ambulance communications centre. The CMC’s role is to:

• initiate and arrange distribution of casualties to appropriate hospital facilities, in conjunction with an ambulance commander—the concept is to distribute casualties to as many hospitals as practicable to avoid facility overload

• alert and mobilise medical teams and other medical and health responders to the disaster scene

• liaise and request activation of health department emergency operation centres at state and regional level if necessary, and provide situation reports at frequent intervals to EOC and to request further assistance

• instigate stand down of the various medical and health responders as appropriate after consultation with the on-site medical coordinator and other emergency service authorities.

Site medical control

The disaster site medical procedures in place for establishing early medical control for the proper triage, treatment and transportation of casualties are initially provided by officers of the first responding ambulance vehicle. These officers carry out the roles of casualty collecting officer (for assessment of numbers and types of casualties, to carry out a reconnaissance of the area and select an area suitable to set up a casualty collecting post, to report findings to ambulance control and to commence triage of casualties) and transport control officer (to establish suitable access and turn-around for ambulance vehicles and to report this information to ambulance communications centre for further incoming response vehicles).

As an AMC or ambulance commander arrives on site, further assessments will be made and a joint medical command post established. All incoming medical responders report to the command post where tasks within the CCP are allocated. Further medical assistance required on site is requested through the central medical coordinator to avoid convergence and duplication of resources. A typical communication structure is outlined in Figure 22.1.

Figure 22.1 On scene communication links and communication pathways

The medical services provided on site will be limited initially, using the principle of doing as little as possible, as simply as possible, as quickly as possible and to as many as possible.

Life-saving procedures, such as airway management, immediate decompression of tension pneumothorax, arrest of haemorrhage, fracture stabilisation and relief of pain where necessary, may be the limit of medical assistance where medical resources are few. Thus effective triage or classification of casualties by a casualty collecting (ambulance) officer (CCO), medical officer or team leader from a medical team is essential.

Figure 22.2 Linkage to other emergency services organisations

Triage and reverse triage

Triage generally implies direction of clinical resources to the most seriously ill or injured by a trieur or triage officer. In a mass casualty situation, demand may be in excess of resources availability. It is neither ethical nor practical to classify clearly non-salvageable victims as top priorities. Given this, two methods of field or mass casualty triage are employed, depending upon the number of casualties and the availability of clinical resources. The two methods of triage—SIEVE and SORT—are utilised at different phases of casualty management at disaster sites.

Sieve

This triage method is used during the initial phase of managing mass casualties. It focuses on determining which patients will survive and channels resources to initially moving that cohort of patients from the scene to a casualty clearing post or station. Triaging in this manner is a repeated process to ensure refinement of urgency stratification and to respond appropriately to the ongoing evolution of a casualty’s injury complex and consequent physiology.

Casualty assessment is based upon the findings of a primary survey. If casualties are ambulant, they are initially regarded as walking wounded and are directed or escorted to a casualty clearing post. If not ambulant, a triaging primary survey is performed. This looks at the airway, respiratory rate and capillary refill. Treatment is limited to the institution of simple life-saving primary survey manoeuvres. These are:

• airway clearance by manual or other available methods

• decompression of a tension pneumothorax by needle thoracostomy

• control of external haemorrhage

• appropriate positioning of unconscious patients or patients with head, chest, abdominal pelvic or spinal injuries.

Casualties must be re-triaged on the basis of response, injury pattern and likely prognosis. If critically injured or ill patients are unresponsive to these measures and unlikely to survive, they become second priority casualties. This is sometimes known as reverse triage

A standard clinical reasoning scheme for triage is outlined in Figure 22.3. SIEVE triage categories are as follows:

1. Top priority patients are those who are severely injured and in need of urgent emergency care. They are those in whom there is actual physiological embarrassment. Treatment is generally urgent, quick, simple and minimal in an endeavour to stabilise prior to priority transportation. They are patients who are deemed as able to be saved but will die or suffer major disability if not treated (Table 22.1).

2. Second priority patients are those who may have significant injuries but in whom airway is not problematic and who have normal respiratory or perfusion status assessments. They constitute most of the injuries that are time-critical on a pattern of blunt injury. The implication of being stratified as a second priority patient is that transfer to and treatment at hospital is required.

3. Second priority patients with a black stripe. A black stripe may be drawn on a second priority tag by a trieur. This identifies that injuries sustained are likely to be incompatible with survival and that extensive medical treatment will jeopardise the survival of other casualties. An example is a patient with 90% burns when there are many patients with survivable injuries. Such casualties require a decision to be made to transfer to hospital as third priority or die at scene.

4. Dead. These are deceased individuals. They need to be certified as dead in the history section of the triage tag by a medical practitioner. The deceased becomes the responsibility of the police and the state coroner. They are generally transferred to a mortuary area on site.

5. Walking wounded patients are divided into those who require physical first aid and those who require mental health first aid. In both instances this could be provided at the scene in a field hospital or similar setting and the patient is then discharged to appropriate continuing care providers.

6. Plain walking wounded tag. These are casualties with either physical injuries or who are medically unwell. They are those who have sustained minor injuries or have non-time-critical medical problems unlikely to require hospital admission.

7. Walking wounded tag with black stripe. This tag identifies casualties with acute mental health problems due to psychological trauma or stress. In general, these casualties are suitable for urgent defusing or counselling, preferably on site. Ongoing care can be planned for a later time.

Figure 22.3 Approach to triage using the SIEVE method

Table 22.1 Triage groupings and criteria for mass casualty situations

Group	Priority	Criteria
1	Red—priority 1	Severely injured but salvageable In need of urgent medical care Urgent resuscitation and transportation required

2 Yellow—priority 2

Significant injuries and condition stable

Treatment can wait or patient is unlikely to live and extensive medical care will jeopardise the survival of other casualties

3 Green—minor injuries

Casualty ambulant (walking wounded) and hospital admission unlikely

Uninjured psychologically disturbed persons included in this category

4 Black—deceased

Medical officer is required to certify death on card

Body becomes the responsibility of police/coroner’s office

SORT

This triage method is the more formal risk stratification or triage system that identifies the urgency with which most emergency health workers are familiar. SORT identifies time-critical patients and assists in scheduling optimal allocation of available resources. If used in the initial triage, this mode of triage is applicable for incidents involving only a small number of casualties. It is more commonly used on admission to casualty collecting posts or field hospitals.

This method of triage is based on the Revised Trauma Score and is consistent with the Australasian Triage Scale, triage practices taught in emergency management of severe trauma (EMST), emergency life support (ELS), advanced paediatric life support (APLS) and major incident medical management and support (MIMMS) courses. It is identical to the practices employed by ambulance, first responder and other emergency medical services personnel for determining the time-critical patient. It is a repeated process that is dependent upon traditional ongoing patient observation.

SORT is generally implemented in the field utilising the Revised Trauma Score in order to rank physiological embarrassment and allocating an ordinal score. This assists with re-prioritisation or risk stratification of casualties. Scores of 1–10 are associated with the immediate category. A score of 11 identifies an urgent patient. A score of 12 or higher identifies casualties that can wait for delayed management (Figure 22.4).

Figure 22.4 The Revised Trauma Score and the SORT method of triage

Further refinement of triage can be assisted by attention to pattern of injuries or mechanism of injuries. However, in a trauma related mass casualty incident, a considerable number of patients may be classified as time-critical on mechanism of injury alone (Table 22.2). Close observation of this latter group is necessary. Although these patients are of lesser priority owing to normal physiological parameters or the absence of an identified pattern of injury, they are victims of major trauma, have sustained major forces and are at risk of significant and occult internal injury.

Table 22.2 Features defining victims of severe trauma or time-critical patients

First aid services

First aid services can be provided by several different organisations. The common ones are St John Ambulance Australia and Australian Red Cross. These may be complemented by other first aid providers such as the Australian Ski Patrol Association, Royal Life Saving Society or Surf Life Saving Australia, depending on the circumstances. First aid agencies are often activated by the ambulance service. Several states have first aid subplans to assist with delineation of command structure, roles and responsibilities.

The principal role of first aid organisations is to assist with minor injuries where the setting up of separate treatment centres are necessary to cope with walking wounded. First aid teams generally work under the direction of a medical coordinator or ambulance commander in casualty collecting posts or holding areas or in field hospitals.

Hospital external disaster or emergency management plans—‘Respond Brown’

All public hospitals are required to have external disaster plans to cope with mass casualties directed to hospital facilities for treatment. Public hospitals are required to develop, implement and test contingencies for the reception of mass casualties. This is a requirement both of legislature and of the Australian Council on Healthcare Standards. Some private hospitals participate in counterdisaster planning activities. These generally assist with walking wounded and second priority patients.

Such plans may also include the procedures for providing a trained and equipped medical team for casualty treatment at a disaster site. The provision of medical teams may reduce the emergency department effectiveness. Consideration is given to replacing or providing a team from another facility if the responding hospital is to continue to be a major casualty receiving hospital.

Certain first aid organisations such as St John Ambulance and the defence forces are also able to provide medical teams on request. Some base hospitals in rural regions also have the capability to provide such teams, with smaller hospitals having a reduced capability.

Planning, exercises and review of plans

All participating agencies integral to Medical DISPLAN response have subplans to ensure effective response is available when required. Integrated medical response planning with other emergency services takes place at all levels, addressing various hazards that exist. The exercising and testing of plans takes place at frequent intervals and as necessary following planning reviews.

Health service emergency management plans

The role of a health service in responding to external incidents will be dependent upon the size and scope of health care services usually offered. Health services that offer acute, subacute, long-term care and community outreach health care have a greater capacity to manage demand and overflows. Smaller hospitals can contribute by providing care to patients or casualties not requiring intensive resources or by assisting in decanting convalescing patients from other acute services, thus freeing resources to receive disaster victims.

Phases of the external disaster plan

In general the phases of an external disaster emergency management plan are alert, standby, activation (declared or action), stand down and debrief.

Activation (action or declared)

Emergency department response

In-hospital responses

The management of in-hospital responses and executive management issues are beyond the scope of this chapter. However, Box 22.1 identifies the other departments and resource areas that contribute to the overall response.

Site medical teams

Some health services are expected to provide site medical teams to work in casualty collecting posts and in field hospitals. These teams assist in the rescue, triage and treatment of disaster victims. The roles will vary depending on the magnitude of the disaster, numbers of casualties and types of problems.

The team may consist of seven personnel—team leader, two further doctors, three emergency nurses and a patient services assistant. The exact nature of this team will depend upon the personnel available and the nature of the disaster to which the team has been called. In general, it is desirable to have the most experienced personnel possible on this team. Thus, they should be recruited from the senior medical staff and nursing staff of three or four years’ experience following qualification.

Stand down

The cessation of the response and return to usual operations is initiated by the ECC. The response may conclude on the advice from the disaster site or a Medical DISPLAN coordinator through the ambulance communication centre. However, the response plan may require ongoing activation until pressure on the health service or hospital resources has subsided and normal actives can be resumed.

The stand down mechanism may be total or progressive. Progressive stand down can be initiated when certain areas are no longer required to function under response plan conditions.

Debriefing

There are two types of debriefing, operational debriefing and psychological debriefing. The latter has two components: immediate debriefing is a defusing of staff; formal counselling is offered for ongoing symptoms.

CHEMICAL, BIOLOGICAL AND RADIOLOGICAL HAZARDS

The approach to chemical, biological and radiological (CBR) exposures is similar in principle to multicasualty trauma incidents whether exposed victims are single casualties, several or within the context of mass casualties. The prime difference is the need to prevent contamination and/or infection of rescuers, health providers and the community. The approach aims to provide optimum care while maintaining safety for other patients and staff. A second broad aim is to effectively decontaminate patients prior to entering the emergency department. It focuses on a sequence of actions and interventions that admits decontaminated casualties to emergency departments. A further aim is the expedient identification of causal agents that may enable specific treatment.

Acute recovery incorporates the restoration of areas used for decontamination to usual functions. It includes management of contaminated items for cleaning and inspection by hazard management or public health agencies. Where applicable, non‑disposable medical equipment is cleaned and returned to regular use. Some contingency plans include specific equipment kits reserved for use in CBR incidents.

In the field, the sequence begins with identification of casualties and proceeds to isolation, decontamination, triage, treatment and transport to hospital. Emergency department contingences are similar. However, treatment may need to commence before or concurrently with decontamination. The main risk for hospitals is the arrival of contaminated or infected individuals prior to recognition or advice of a CBR incident with consequent contamination of the emergency department and, potentially, the whole health facility.

Chemical agents

Nerve agents

Nerve agents are organophosphates. They block acetylcholine esterase inhibitors, causing a cholinergic crisis. Examples include Tabun (GA), Sarin (GB) and VX.

Blistering agents

These irritate the epithelial surfaces by direct contact. The skin and mucosal surfaces are the target tissues. The mustard agents and lewisite are examples of this group.

Incapacitating agents

This group causes short-term disabling physical and/or mental effects by affecting higher cortical function. The group includes central nervous system depressants, stimulants and hallucinogens. To qualify for membership of this group, agents must be potent, last hours to days, not be potentially lethal at effective doses and have no long-term adverse sequelae. LSD and 3-quinclidinyl benzoate (BZ) are examples of incapacitating agents. BZ is an anticholinergic agent.

Blood agents—the cyanides

These agents impair cellular function by uncoupling oxidative phosphorylation.

Pulmonary/choking agents

Choking agents impair the respiratory system by irritating the respiratory tract mucosa and alveolar epithelium. These can produce a spectrum of illness from minor irritation to acute respiratory distress syndrome. Examples include chlorine (CL) and phosgene (GC).

Biological hazards

These are varied. Illness is usually of insidious onset. Because early symptoms may be non-specific, especially when patients may be prodromally unwell, early recognition can be difficult. Once the community is aware, workload is increased. Patient load will include those with non-specific symptoms, worried patients with usual clinical features of a non-exposure-related illness and those with unusual symptoms or clinical signs needing diagnostic refinement.

Patients exposed to microbiological agents may be recognised when a number of patients present with unusual similar symptoms or clinical signs. Alternatively an influx of patients with similar symptoms may present with diagnostic refinement identifying a common broad illness such as pneumonia with isolation of an unusual causal agent. Other dilemmas include when to immunise and when to definitively treat. These decisions must be made in conjunction with infectious disease physicians and public health agencies. Rationalisation of available therapeutic substances is a logistical problem. The principles of managing this issue are no different to those of disaster triage and reverse triage. However, within this context, development of inclusion and exclusion criteria is more relevant. The impact of the espouser on hospitals is likely to increase the workload of laboratory facilities in initial identification and ongoing examinations for isolation of infective agents or bacterial endotoxins and exotoxins.

Radiological hazards

Two broad questions need to be asked when considering radiological exposure. Has the patient been irradiated? Is the patient radioactive? Irradiation alone can cause life-threatening illness. The latter additionally poses a risk to rescuers and ongoing careers.

All forms of ionising radiation can cause illness. Alpha particles generally have poor tissue penetration. They are of significance if ingested, inhaled or have contacted open wounds. Gamma rays penetrate tissues, directly affecting cells. Neutrons cause effects indirectly. Human tissue provides some resistance to Beta particles, thus decreasing impact and causing only tissue damage when they have penetrated cells. Bone marrow and gastrointestinal mucosa are tissues at most risk. Injuries may be caused by a single radiation exposure, exposure to high levels of fallout and repeated exposures.

Acute radiation syndrome involves four phases: prodrome, latent period, manifest illness and death or recovery.

Prodrome

Initial symptoms often appear within 6 hours of exposure. Symptoms include nausea, vomiting, anorexia and general malaise. Treatment is largely symptomatic and supportive. A 48-hour lymphocyte count and chromosomal analysis of lymphocytes for dicentric fragments are predictors of likely bone marrow suppression and haempoietic syndrome (see Figure 22.5).

Figure 22.5 Lymphocyte count as a guide to severity of haempoietic syndrome

Reproduced with permission from Emergency management practice manual 3: health aspects of chemical, biological and radiological hazards. Provisional edn, In: Australian emergency manuals series, part 3. Emergency Management Australia; 1999

Latent period

This phase is a variable symptom-free period of hours to weeks.

Manifest illness

In this, definitive radiation illness and its complications become evident. Four clinical syndromes are described: haempoietic, gastrointestinal, vascular and cerebral

The symptoms of the gastrointestinal syndrome are similar to those of the prodrome phase with additional problems of diarrhoea, fever and gastrointestinal haemorrhage. Bowel perforation and septicaemia are complications of severe illness. Treatment is supportive with intravenous fluid resuscitation, dehydration and parenteral nutrition

The haempoietic syndrome is the effect of bone marrow suppression with increased susceptibility to infection, haemorrhage and occasionally anaemia. Treatment is generally supportive. Platelet transfusion may be necessary for thrombocytopenia-associated haemorrhage or if surgical intervention is required. Sepsis must be energetically treated. Wounds should be closed as soon as possible. Infected or devitalised tissue should be excised. Early skin grafting of burns prevents opportunistic infection. Other blood products to enhance immunocompetence may be considered as clinically indicated

The vascular syndrome is due to vascular bed dilation and capillary leaking. Shock occurs as a result of volume loss and poor vascular resistance, due to stimulation of acute inflammation and release of vasoactive humoral mediators causing peripheral vasodilation.

The cerebral syndrome comprises nausea, vomiting, cardiovascular instability, confusion, ataxia, seizure and loss of consciousness. There is a high mortality within 24–48 hours.

Recovery/death

Death or recovery over several weeks are sequelae of the illness.