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Simulation sixteen: Structural search and rescue (hot-fire cell: in pairs) .1 Subjects

The 15-point Borg scale 6

2.19 Simulation sixteen: Structural search and rescue (hot-fire cell: in pairs) .1 Subjects

For this occupational activity, eight firefighters who had not participated within any of the previous simulations were involved (including one woman: Table 14).

2.19.2 Simulation description

This simulation occurred within the hot-fire cell at the Alexandria Training College. This is three-storey, concrete structure containing steel stair cases and floors. The tasks performed by each firefighter were wholly controlled by Training Officers, and involved the dragging of a charged hose to the third floor, the rescue of two victims (70-kg and 50-kg dummies) and various movements and equipment carriage within the structure, as dictated by these Officers (Figures 16 and 17).

Table 14: Characteristics of firefighters performing the hot-fire cell simulation. Fire Stations: Darlinghurst and Redfern.

Subject Rank Age (y) Experience (y) Height (cm) Body mass (kg)

S44 SO 36 13 171.00 90.10

S45 QFF 25 5 193.00 70.40

S46 FF 30 1 177.80 102.50

S47 QFF 35 4 181.40 87.25

S48 SO 52 28 173.80 87.10

S49 SFF 36 6 169.30 70.80

S50 SFF 38 7 184.40 80.70

S51 FF 28 1 180.60 71.85

Mean 35.0 8.1 179.00 82.60

SD 8.2 8.9 7.67 11.35

This simulation was included at the request of the Research Team, since it provided, within a single task, an opportunity to join several tasks into a single simulation that would have high ecological validity8, and for which the Research Team had collected preliminary data Taylor et al., 2010). Each firefighter performed the simulation twice (once under heat and smoke, and once without). Six platoons supported this activity, with two platoons fulfilling

the roles of experimental subjects (one person at a time) and with one firefighter from the other platoons accompanying each experimental firefighter, and providing assistance as would occur within a structural fire scenario. This rotation of firefighters minimised the strain encountered by any one firefighter, and ensured that each of the experimental

firefighters commenced the simulation in a well-rested and normothermic state. Firefighters wore full thermal protective and station-wear clothing, protective boots, breathing

apparatus, helmets, radio (1.1 kg) and data acquisition system (mean total mass: 24.10 kg).

During the first simulation, firefighters used self-contained breathing apparatus (Figure 16).

The average temperature of the cell was regulated between 68-73oC, but varied throughout the cell. The Research Team did not accompany the firefighters on this simulation. Since the cell has no windows, and since all lights were extinguished and the cell was filled with smoke, visibility was reduced to zero. The durations of this simulation were set by several criteria. Firstly, since it is well known that elevations in core temperature are a function of both work rate and exposure time, then the Research Team was interested in evaluating the impact of a more prolonged thermal stimulation. The Team was also advised that, under some circumstance, firefighters may be required to change breathing apparatus and re-enter a building. Therefore, firefighters were asked to continue the simulation as long as possible, and this may include changing breathing apparatus. Only one firefighter was able to

continue the simulation beyond the use of one set of breathing apparatus. Secondly, there were two firefighter withdrawal criteria set by the Research Team: the attainment of a core temperature >39.5oC (checked on each exit from the cell), or a desire of the firefighter to withdraw for any reason. Two firefighters reached this temperature limit. One firefighter asked to be withdrawn due to fatigue, and, on withdrawal, was found to have a core temperature of 39.35oC. Thirdly, if air cylinder pressure fell below 5 MPa for anyone within the cell, a warning signal was triggered, and all firefighters immediately left the cell.

This criterion led to the termination of four additional simulations, but since the core

temperatures of these individuals were >39oC, they were not asked to continue. Finally, the Training Officers were at liberty to terminate the simulation if they felt that firefighter health and safety was at risk. One firefighter was withdrawn on this basis. These

simulations lasted an average of 25.64 min (SD 5.10), with ratings of perceived exertion being recorded at the conclusion of the simulation.

On the following day, these firefighters repeated each scenario, but now also wearing portable expired gas analysis equipment (Figure 17). These simulation replications lasted an average of 19.57 min (SD 4.22). The lights were extinguished as per the first simulation, but heat and smoke were not used. Air temperature was 24.6oC. The Research Team accompanied firefighters, who replicated their own individual scenario, as instructed by the Training Officers. Ratings of perceived exertion were recorded upon the completion of specific sub-tasks, as determined by the Research Team.

Figure 16: The structural search and rescue simulation (hot-fire cell).

Figure 17: Firefighters performing a structural search (left) and rescue simulation (right) in the hot-fire cell, but without heat and smoke, whilst wearing portable open-circuit spirometry apparatus.

Simulation scenarios (day two):

Subject 44:

Initial search with hose from ground to top of third floor

50-kg dummy removed from third floor and dragged to ground floor Dragged 50-kg dummy back up to the third floor

Walked down from third floor (dragging hose) to ground floor Secondary search of the ground floor

Removal of hose and exit building.

Subject 45:

Initial search with hose from ground to top of third floor

70-kg dummy removed from third floor and dragged to ground floor Walk up to the third floor

Drag hose to ground floor and exit due to cylinder change Drag 70-kg dummy back up to the third floor

Secondary search of all floors with hose en route to ground floor Removal of hose and exit building.

Subject 46:

Initial search with hose from ground to top of third floor

50-kg dummy removed from third floor and dragged to ground floor Walk back up to the third floor

70-kg dummy removed from third floor and dragged to ground floor Secondary search of all floors with hose en route to ground floor Removal of hose and exit building.

Subject 47:

Initial search of ground floor

Drag 50-kg dummy up to the third floor Walk down to ground floor

Drag 70-kg dummy up to the third floor Drag hose up to the third floor

50-kg dummy removed from third floor and dragged to ground floor Ground floor secondary search and exit building.

Subject 48:

Initial search with hose from ground to top of third floor

70-kg dummy removed from third floor and dragged to first floor.

Walk down to ground floor, secondary search and exit building.

Subject 49:

Initial search of the ground and first floors

Drag 70-kg dummy from the first to the third floors

Drag hose from third floor to ground floor and remove hose from building Walk up to the second and third floors and conduct final search

Return to ground floor and exit from building.

Subject 50:

Initial search from the ground to the third floors

70-kg dummy removed from third floor and dragged to ground floor Drag 50-kg dummy from the ground floor to the second floor

Walk down to the ground floor

9 The standard deviation is a measure of variability (distribution) of the observed results around the mean.

10 Box plots are summary graphs that present three descriptive details for each data set in the form of a rectangle (box). The lower boundary of the rectangle indicates the 25th percentile, whilst the upper border shows the 75th percentile. A line is shown within the box, and this marks the median value for these data.

Drag hose to the third floor

Walk down to ground floor and remove 70-kg dummy from building Final search of all floors, return to ground floor and exit from building.

Subject 51:

Initial search of the ground floor Drag 70-kg dummy to the second floor Search of the second and third floors

Return to the ground floor and exit from building.