Firefighter hemodynamic responses to different fire training environments.

Firefighting is associated with an increased risk for a cardiovascular (CV) event, likely due to increased CV strain. The increase in CV strain during firefighting can be attributed to the interaction of several factors such as the strenuous physical demand, sympathetic nervous system activation, increased thermal burden, and the environmental exposure to smoke pollutants. Characterizing the impact of varying thermal burden and pollutant exposure on hemodynamics may help understand the CV burden experienced during firefighting. The purpose of this study was to examine the hemodynamic response of firefighters to training environments created by pallets and straw; oriented strand board (OSB); or simulated fire/smoke (fog). Twenty-three firefighters had brachial blood pressure measured and central blood pressure and hemodynamics estimated from the pressure waveform at baseline, and immediately and 30 minutes after each scenario. The training environment did not influence the hemodynamic response over time (interaction, p > 0.05); however, OSB scenarios resulted in higher pulse wave velocity and blood pressure (environment, p < 0.05). In conclusion, conducting OSB training scenarios appears to create the largest arterial burden in firefighters compared to other scenarios in this study. Environmental thermal burden in combination with the strenuous exercise, and psychological and environmental stress placed on firefighters should be considered when designing fire training scenarios and evaluating CV risk.

Electrocardiographic Responses Following Live-Fire Firefighting Drills.

OBJECTIVE: Firefighting-related environmental and physiological factors associated with cardiovascular strain may promote arrhythmias and myocardial ischemia, which induce sudden cardiac events (SCE) in susceptible individuals. The present study evaluated electrocardiographic (ECG) changes that may reflect increased SCE risk following simulated live-firefighting. METHODS: Using a repeated measures design, ECG tracings from 32 firefighters were recorded 12-hours post-firefighting in a residential structure and compared with a 12-hour control period. RESULTS: Ventricular arrhythmias were present in 20%, and ST segment changes indicative of myocardial ischemia in 16%, of firefighters 12-hours post-firefighting that were not detected in the control period. CONCLUSION: Live-firefighting induces significant ECG changes that include ventricular arrhythmias and ST segment changes, which may reflect myocardial ischemia. The implications of such ECG changes explaining increased cardiovascular risk in firefighters warrants further research.

Exposure to a firefighting overhaul environment without respiratory protection increases immune dysregulation and lung disease risk.

Firefighting activities appear to increase the risk of acute and chronic lung disease, including malignancy. While self-contained breathing apparatuses (SCBA) mitigate exposures to inhalable asphyxiates and carcinogens, firefighters frequently remove SCBA during overhaul when the firegrounds appear clear of visible smoke. Using a mouse model of overhaul without airway protection, the impact of fireground environment exposure on lung gene expression was assessed to identify transcripts potentially critical to firefighter-related chronic pulmonary illnesses. Lung tissue was collected 2 hrs post-overhaul and evaluated via whole genome transcriptomics by RNA-seq. Although gas metering showed that the fireground overhaul levels of carbon monoxide (CO), carbon dioxide (CO2), hydrogen cyanine (HCN), hydrogen sulfide (H2S) and oxygen (O2) were within NIOSH ceiling recommendations, 3852 lung genes were differentially expressed when mice exposed to overhaul were compared to mice on the fireground but outside the overhaul environment. Importantly, overhaul exposure was associated with an up/down-regulation of 86 genes with a fold change of 1.5 or greater (p<0.5) including the immunomodulatory-linked genes S100a8 and Tnfsf9 (downregulation) and the cancer-linked genes, Capn11 and Rorc (upregulation). Taken together these findings indicate that, without respiratory protection, exposure to the fireground overhaul environment is associated with transcriptional changes impacting proteins potentially related to inflammation-associated lung disease and cancer.