Firefighter Incident Rehabilitation: Interpreting Heart Rate Responses.

UNLABELLED: The primary objective of this observational study was to document the heart rate (HR) responses of firefighters during incident rehabilitation following firefighting activity in a high-rise building with a simulated fire on the 10th floor. Additionally, the study investigated potential factors, including firefighting workload, ambient temperature, firefighter movement, and individual characteristics, that may have affected HR during recovery. Firefighters (n = 198) were assigned to perform a simulation of fire suppression, search and rescue, or material support during one of six firefighting trials that involved different crew sizes and ascent modes, and were performed in different environmental conditions. After completing the simulated firefighting activity, firefighters reported to a rehabilitation area on the 8th floor. The rehabilitation area was staffed by firefighter/paramedics. HR was monitored continuously during simulated firefighting activity and a 15-minute rehabilitation period. Average HR during rehabilitation (HRmean) was calculated and compared across trials. Simulated firefighting activity was performed in the summer in Virginia, USA, and ambient conditions varied among trials (mean ± SD: 31 ± 4°C; 46 ± 15% relative humidity; 32 ± 4°C heat index). Duration of simulated firefighting activity ranged from 12.0 to 20.3 minutes among trials (mean: 15.4 ± 5.2 minutes). Over all trials, mean peak HR during simulations was 173 ± 18 beats·min(-1). Mean HR over all trials at entry into rehabilitation was 149 ± 24 beats·min(-1). Following 15 minutes of recovery, mean HR over all trials was 126 ± 23 beats·min(-1). Exploratory analyses revealed that higher workload during firefighting (stair trials), higher ambient temperature (≥30°C), greater movement during rehabilitation (≥0.1 g-force), higher age (≥45 years), and higher BMI (≥30.0 kg·m(-2)) were associated with higher HR responses during rehabilitation. During complex emergency operations, emergency medical service personnel will likely encounter considerable variability in HR responses upon initial evaluation and throughout rehabilitation. Following one bout of firefighting activity during a simulated fire scenario, HR decreased but remained elevated well above resting values following 15 minutes of rehabilitation. Based on current fire service recommendations, the majority of firefighters (88%) would not have been released from rehabilitation and eligible for reassignment after a 15-minute rehabilitation period following a brief bout of simulated firefighting activity. KEY WORDS: medical monitoring, cardiac strain, firefighting.

Cardiac strain associated with high-rise firefighting.

Although numerous studies have reported the physiological strain associated with firefighting, cardiac responses during a large-scale fire operation have not been reported and cardiac responses have not been compared based on crew assignment. The aims of this study were (1) to characterize cardiac strain during simulated high-rise firefighting, and (2) to compare the cardiac strain associated with different work assignments (fire suppression vs. search and rescue) and different modes of vertical ascent (stairs vs. elevator). Firefighters (N = 42) completed one assignment (fire suppression, search and rescue, or material support) during one of two trials that differed by ascent mode. Assignments were divided into three phases: Ascent (ascend lobby to 8th floor), Staging (remain in holding area on 8th floor), and Work (perform primary responsibilities). When comparing assignments within the same ascent mode, mean heart rate (HRmean) was higher (p = 0.031) for fire suppression than for search and rescue during Work in the stair trial (170 ± 14 vs. 155 ± 11 beats/min). Search and rescue crews experienced greater cumulative cardiac strain (HRmean × duration) during Work than did fire suppression crews (stairs: 1978 ± 366 vs. 1502 ± 190 beats; elevator: 1755 ± 514 vs. 856 ± 232 beats; p<0.05). When comparing ascent mode, HRmean and peak heart rate (HRpeak) were higher (35-57 beats/min; p≤0.001) for both fire suppression and search and rescue during Ascent and Staging phases in the stairs vs. the elevator trial. During Work, HRmean was higher (p = 0.046) for search and rescue in the stairs vs. the elevator trial (155 ± 11 vs. 138 ± 19 beats/min). HRmean and HRpeak were 47 and 34 beats/min higher (p < 0.01), respectively, when materials were transported to the staging area using the stairs compared with the elevator. Study findings suggest that high-rise firefighting results in considerable cardiac strain and that search and rescue and material support crews experienced more cardiac strain than fire suppression crews due primarily to differences in assignment duration. Furthermore, using stairs to transport firefighters and equipment to upper floors results in significantly greater cardiac strain than using the elevator.