Multidisciplinary team response to a mass burn casualty event: outcomes and implications

On 7 February 2009, devastating bushfires in the state of Victoria caused one of Australia’s worst-ever disasters. There were 173 people killed and more than 400 injured in the “Black Saturday” fires.1 Thousands of dwellings and other infrastructure were destroyed. As a result of the fires, 19 patients with burn injuries were admitted to The Alfred Hospital (The Alfred), a major trauma hospital in Melbourne that houses the Victorian Adult Burns Service (VABS). VABS is the state’s only adult burns service, treating 250–300 acute burn-injured inpatients each year.

Severe burn injury is an uncommon event in Western societies, and it is well recognised that burn health care resources are soon overwhelmed by relatively small numbers of patients with significant burn injuries in a mass casualty setting.2 Victoria’s mass casualty burns plan defines a mass burns casualty as an event causing burns injuries that exceed or are likely to exceed the ability of the burns unit to manage them (five or more severe burn injuries is the figure used as a guide).3

Reports of bushfires in Canberra4 and San Diego5 have focused on pre-hospital planning and emergency department management rather than the overall experience of a multidisciplinary unit. In recent Australian history, the most similar event was the Ash Wednesday bushfires of 1983 in which 75 people died;6 however, the medical literature on these fires relates to psychological trauma.7,8 Mass casualty events that have been studied in terms of burn centre responses include the terrorist attacks in New York, NY9 and Washington, DC in 2001,10 and Bali in 2002.11

Our study describes the characteristics of admitted patients, analyses the hospital response, and highlights the resource requirements for an adequate response to this incident. The circumstances of the injuries placed a number of these people at high risk of infective and other complications.

Burns > 20% TBSA are considered “severe” in the setting of a mass casualty incident, and seven patients admitted to VABS as a result of the bushfires had what is defined as a severe burn injury. To put this in context, an average of 35 patients a year in the state of Victoria received burns of > 20% TBSA in the years 2000–2006.15

The requirement for ICU beds when treating burn patients is frequently the limiting factor in the acute response to mass casualty incidents,16 as patients with airway injury or extensive burns necessitating large doses of opiates for analgesia require intubation and ventilation. The acute creation of 10 additional ICU ventilator beds at The Alfred has been documented elsewhere.1

Disaster plans focus on the triage and distribution of casualties to hospitals. While it has been increasingly recognised in recent years that burns patients require large amounts of resources — human, infrastructural and consumable — what this actually means in terms of capacity is difficult to quantify. The delayed demands on such resources are increasingly difficult to measure as time from the incident elapses, yet burns patients have notoriously prolonged and complex hospital stays, and require lengthy rehabilitation and secondary surgery.

In terms of calculating what the theatre requirements of a particular burn patient are likely to be, for the group with burns between 10% and 50% TBSA, 21 minutes of theatre time per %TBSA burn for the whole inpatient stay would seem to provide a reasonable estimate, based on experiences at Middlemore Hospital and VABS. This estimate can be used in the event of a mass burn casualty event to determine the ability of a hospital to provide appropriate care for the cohort of patients with 10%–50% TBSA burns. Theatre demands are maximal in the first week and decrease rapidly thereafter, at least halving in each subsequent week.

However, attempts to predict the requirements of patients with massive burns are far more problematic and uncertain. It has been estimated that for the state of South Australia, five adult patients with massive burns would consume all normal burns unit resources for at least 3 months, after requiring a minimum of 5 hours each of surgery per week for the first 3 weeks.17 A patient with > 50% TBSA burns has insufficient donor sites to provide early definitive wound closure, and is prone to a multitude of complications, making for a highly idiosyncratic clinical course. Add to this the fact that these are relatively uncommon injuries (most Australian burns units would admit around three to four such patients a year, some of whom might be treated palliatively), and it becomes very difficult to produce meaningful average data. The presence of people with burns > 50% TBSA in a mass casualty cohort increases both acute and longer-term resource requirements exponentially, as well as greatly extending the length of time of increased demands, and would significantly complicate decision making with respect to resource allocation. The recently established Australia and New Zealand Bi-National Burns Registry will provide comprehensive data on these uncommon injuries and aid in predicting resource requirements.

The ability to provide early total burn wound excision is crucial in minimising complications in burns patients18 — especially in those with severe burns (> 20% TBSA) who are at risk of developing systemic complications19 — which consume extra resources over increasing time periods in an already pressured environment. A hospital responding to a mass burn casualty event must, as a priority, ensure that theatres and surgeons are acutely available to enable early excision of severe burns. This strategy will minimise ongoing demands for resources and ensure best outcomes for patients. If excision is delayed, complications increase, hospital stays drag out, and the drain on resources limits the institution’s ability to return to business as usual quickly.

In the aftermath of the 2009 bushfires, VABS was able to continue to admit and treat all patients who met the criteria for transfer to a specialist burns unit according to the Australia and New Zealand Burn Association guidelines. However, in a true mass casualty situation, patients with burns < 20% TBSA may well require admission to a non-specialist facility in order to allow the specialist burns referral centre to continue to manage more severe and complicated burns injuries.

The amount of fluid resuscitation in the VABS bushfire cohort is comparable to results previously obtained at the same institution.20 The mean amount of fluid received exceeded that calculated by the Parkland formula and reflects the recent trend towards “fluid creep” in burns resuscitation.21 However, many of the patients were dehydrated on presentation through a combination of burns injury, high ambient temperatures (> 46° C) and delayed presentation to hospital. The increased rate of renal impairment compared with the matched cohort may reflect this. The infectious complications in patients with histories of exposure to contaminated water are in keeping with recent literature.22

It is important to recognise that victims of a mass casualty event have needs beyond medical treatment. Many of our patients had lost family members, homes, livestock and their livelihoods. They had significant loss and grief issues. In addition to the provision of medical treatment, The Alfred dealt with media issues, provided psychological support, and responded to the social needs of these patients and their families as part of the statewide response to this unprecedented catastrophe.

There were relatively few patients with severe burns admitted as a result of the bushfires when compared with the number of lives lost. This may reflect the extreme conditions created by the firestorms experienced on 7 February 2009 and that most people trapped by the fires perished. Nonetheless, significant increases in resource allocation were required to manage the survivors with burn injuries. Analysis of this resource allocation can assist in planning for future mass burn casualty incidents.

3 Theatre usage time following the Victorian bushfires, by percentage of total burn surface area (%TBSA), February–March 2009

4 Daily theatre usage following the Victorian bushfires, February–March 2009

5 Total weekly theatre usage following the Victorian bushfires, February–March 2009

Week 1 = 8–14 Feb 2009. Week 2 = 15–21 Feb 2009. Week 3 = 22–28 Feb 2009. Week 4 = 1–7 Mar 2009.