Immune and inflammatory responses of Australian firefighters after repeated exposures to the heat

Walker, Anthony; Keene, Toby; Argus, Christos K.; Driller, Matthew W.; Guy, Joshua H.; Rattray, Ben

doi:10.1080/00140139.2015.1051596

Cited by 33 publications

(35 citation statements)

References 38 publications

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“…Barr et al ( 2010 ) reported that firefighters were under greater physiological strain in terms of higher heart rates during hot conditions (>40°) compared to temperate conditions (15°–40°) like during the standard simulated firefighting exercise. Similarly, Walker et al ( 2015 ) showed that the completion of a standard work protocol in very hot conditions (up to 100°) resulted in increased core temperature and heart rates (from 74 to 90% HR max ). Extreme conditions (up to 300°) refer to those encountered during a flashover (Barr et al, 2010 ).…”

Section: Discussionmentioning

confidence: 90%

Physiological Responses to Firefighting in Extreme Temperatures Do Not Compare to Firefighting in Temperate Conditions

et al. 2017

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Purpose: The aim of this study was to examine physiological responses to two different simulated firefighting exercises: a firefighting exercise with flashovers, smoke, poor visibility and extreme temperatures (300°) in a burning container and a standard firefighting exercise in temperate conditions. Furthermore, a second purpose of the study was to find out if the contribution of strength and endurance capacities to firefighting performance changes when the demands of the firefighting exercise change.Methods: Sixteen professional firefighters performed a maximum treadmill test, strength testing, a standard simulated firefighting exercise (SFE) without heat and flashovers and a firefighting exercise with a simulation of the flashover phenomenon in a burning container (FOT). The treadmill testing was used to determine peak oxygen uptake (VO2peak), ventilatory threshold (VT1) and respiratory compensation point (RCP). Three intensity zones were identified according to heart rate (HR) values corresponding to VT1 and RCP: zone 1–HR below VT1, zone 2-HR between VT1 and RCP, zone 3–HR above RCP. Firefighting performance was determined by a simple time-strain-air depletion model (TSA) taking the sum of z-transformed parameters of time to finish the exercise, strain in terms of mean heart rate, and air depletion from the breathing apparatus. Correlations were then established between TSA based firefighting performance parameters and fitness variables representing strength and endurance.Results: HR was significantly lower during SFE (79.9 ± 6.9%HRmax) compared to FOT (85.4 ± 5.2%HRmax). During SFE subjects spent 24.6 ± 30.2% of time in zone 1, 65.8 ± 28.1% in zone 2 and 9.7 ± 16.6% in zone 3. During FOT subjects spent 16.3 ± 12.8% in zone 1, 50.4 ± 13.2% in zone 2 and 33.3 ± 16.6% in zone 3. Out of all correlations, relative VO2peak showed the highest relation to mean HR during SFE (−0.593) as well as FOT (−0.693).Conclusions: Endurance in terms of VO2peak is an important prerequisite for both firefighting exercises. However, for standard simulated firefighting exercises it is important to work below VT1. For firefighting exercises in extreme temperatures with smoke, poor visibility and unexpected flashovers a high fitness level is required in order to keep the time spent above RCP as short as possible.

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Section: Discussionmentioning

confidence: 90%

Physiological Responses to Firefighting in Extreme Temperatures Do Not Compare to Firefighting in Temperate Conditions

et al. 2017

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“…Elevated pro-inflammatory cytokines, which, in first responders, may result from environmental exposures [ 21 ], have been linked to depression in the acute phase of PTSD [ 22 – 24 ] and during remission [ 25 ]. Coupled with increases in acute phase proteins, such as complement protein, C-reactive protein (CRP), and haptoglobin, elevated pro-inflammatory cytokines have been observed in major depression [ 17 , 26 ].…”

Section: Pathophysiology Of Depressionmentioning

confidence: 99%

“…A growing body of evidence points to links between elevated core temperature ( T c ) and increased immune system activity. Elevated levels of circulating leukocytes and platelets, and increased inflammatory activity, have been observed in firefighters following simulated work tasks in the heat [ 21 , 60 ]. Strenuous physical activity undertaken in hot environments can also increase circulating levels of lipopolysaccharide (LPS) [ 61 ].…”

Section: Occupational Exposuresmentioning

confidence: 99%

Chronic occupational exposures can influence the rate of PTSD and depressive disorders in first responders and military personnel

et al. 2016

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BackgroundFirst responders and military personnel experience rates of post-traumatic stress disorder (PTSD) far in excess of the general population. Although exposure to acute traumatic events plays a role in the genesis of these disorders, in this review, we present an argument that the occupational and environmental conditions where these workers operate are also likely contributors.Presentation of the hypothesisFirst responders and military personnel face occupational exposures that have been associated with altered immune and inflammatory activity. In turn, these physiological responses are linked to altered moods and feelings of well-being which may provide priming conditions that compromise individual resilience, and increase the risk of PTSD and depression when subsequently exposed to acute traumatic events. These exposures include heat, smoke, and sleep restriction, and physical injury often alongside heavy physical exertion. Provided the stimulus is sufficient, these exposures have been linked to inflammatory activity and modification of the hypothalamic–pituitary axis (HPA), offering a mechanism for the high rates of PTSD and depressive disorders in these occupations.Testing the hypothesisTo test this hypothesis in the future, a case–control approach is suggested that compares individuals with PTSD or depressive disorders with healthy colleagues in a retrospective framework. This approach should characterise the relationships between altered immune and inflammatory activity and health outcomes. Wearable technology, surveys, and formal experimentation in the field will add useful data to these investigations.Implications of the hypothesisInflammatory changes, linked with occupational exposures in first responders and military personnel, would highlight the need for a risk management approach to work places. Risk management strategies could focus on reducing exposure, ensuring recovery, and increasing resilience to these risk contributors to minimise the rates of PTSD and depressive disorders in vulnerable occupations.

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“…Previous studies have noted increases in IL-6 due to heat exposure or exercise (Scharhag et al 2005;Welc et al 2012). Firefighters have also demonstrated increases in IL-6 following 40 min of simulated fire and rescue tasks in the heat (Walker et al 2015).…”

Section: Inflammationmentioning

confidence: 92%

Fire service instructor's undergarment choice to reduce Interleukin-6 and minimise physiological and perceptual strain

Watkins

Richardson

2017

Journal of Thermal Biology

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Fire Service Instructors frequently experience high levels of physiological and perceptual strain during live fire exposures. Instructors are also at risk of cardiovascular illnesses, with cardiac death being the greatest cause of fire fighter death. Current practice for UK instructors is to select undergarment type based on personal preference, between a boiler suit (BOILER) and a wicking base layer (WBL). Research suggests that shorts and t-shirt (SHORTS) may also be a beneficial alternative undergarment choice. The UK South East Fire Service requested an investigation to identify if undergarment selection can lessen the strain experienced by instructors, and reduce the acute inflammatory response to fire exposures. Eight males completed three 45 min sessions in a heat chamber (49.5 ± 1.4°C and 16.9 ± 4.3% RH) whilst performing intermittent walking. At the end of heat exposure change in heart rate was not effected by garment type (p=0.061, p 2 =0.373). Change in rectal temperature was different between garments (p=0.009,  p 2 = 0.271), with trends suggestingthat BOILER resulted in a greater change (1.03 ± 0.60°C) than SHORTS (0.76 ± 0.37°C, p=0.589, d=0.21) and WBL (0.72 ± 0.33°C, p=0.545, d=0.25). Interleukin-6 post exposure was greater for BOILER (6.96 ± 0.28 pg.mL -1 ) than both SHORTS (6.59 ± 0.30 pg.mL p=0.043, p=0.031, d=0.51). Overall, undergarment type had little impact on physiological or perceptual strain. However, wearing WBL or SHORTS may reduce the inflammatory response, and consequently decrease the risk of cardiovascular events. AbbreviationsBOILER, Boiler Suit; PSI, Physiological strain index; SCBA, Self-contained breathing apparatus; SHORTS, shorts and t-shirt; WBL, wicking base layer

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Immune and inflammatory responses of Australian firefighters after repeated exposures to the heat

Cited by 33 publications

References 38 publications

Physiological Responses to Firefighting in Extreme Temperatures Do Not Compare to Firefighting in Temperate Conditions

Physiological Responses to Firefighting in Extreme Temperatures Do Not Compare to Firefighting in Temperate Conditions

Chronic occupational exposures can influence the rate of PTSD and depressive disorders in first responders and military personnel

Fire service instructor's undergarment choice to reduce Interleukin-6 and minimise physiological and perceptual strain

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