Responding to sudden onset disasters in South East Asia and the Western Pacific requires teams of medical personnel to work in hot and seasonally humid environments. Recent Australian Medical Assistance Team (AusMAT) deployments post Typhoon Haiyan (Philippines, 2013), Tropical Cyclone Pam (Vanuatu, 2015), and Tropical Cyclone Winston (Fiji, 2016) exposed responders to such conditions. With the exception of Australia’s northern tropics that experience hot weather year round (), such conditions are in contrast to the temperate climate experienced by the vast majority of Australians. In order to assemble highly skilled, trained, and accredited AusMAT, members may be recruited from all Australian states and territories, creating the potential for disparity between the climate that team members are accustomed to living and working in, and that of the deployment region. This is an important workplace health and safety consideration, as team members are expected to work 12 h shifts over 14 consecutive days (). Sustained exposure to hot and humid work conditions increases the risk of heat stress, impacting both individual team member health and the delivery of medical services to those in need. While strategies are available to mitigate responder heat stress (–), most approaches are resource dependent and may therefore not be feasible in austere disaster settings. By contrast, heat acclimatization, defined as the physiological and perceptual adaptations conferred by frequent elevations of core temperature, is a mitigation strategy that can be developed and maintained in the home environment in readiness for deployment.
A recent report from hot and humid field conditions (mean 34°C, 48% relative humidity) highlighted the value of heat acclimatization in a simulated disaster setting by comparing physiological variables of heat acclimatized (HA) and non-heat acclimatized (NHA) responders. Despite similar physiological values during the initial stages of disaster response, HA responders sustained a significantly higher mean core temperature (38.5°C) than their NHA counterparts (38.1°C) (). This seemingly counterintuitive outcome is in contrast to laboratory-based fixed workload research that results in less physiological perturbation following completion of a structured heat acclimatization program (). The key discrepancy between settings is the self-paced workload, allowing HA responders to seemingly adopt a higher output, greater metabolic heat production, and body heat storage than the NHA cohort. Interestingly, both cohorts reported their thermal sensation as “hot” and thermal discomfort as “uncomfortable” despite the core temperature discrepancy, symbolic of both groups regulating their work output according to how hot they felt (). The apparent dissociation between core temperature and thermal sensation was likely due to the chronic exposure to hot working conditions of the HA responders, habituating them to feeling warm/hot. With similar pre-shift hydration status and overall dehydration, differences between cohorts could not be attributed to hydration. Despite their apparent pacing of effort, 63% of the NHA cohort reported ill to the onsite medical team during the simulation compared to 25% of HA responders. In summary, HA responders demonstrated superior heat tolerance than their NHA counterparts.
Currently, heat acclimatization is not formally recognized alongside accreditation, vaccination, medical clearance, and completion of deployment training as prerequisites for AusMAT deployment. Reports of disaster responders suffering heat stress (–) complement the research evidence supporting deployment of HA responders to hot climates. We therefore make the case for consideration of heat acclimatization in the determination of an individual responders suitability for deployment where heat will be encountered.
The nature of sudden onset disasters precludes provision of substantial notice of initial disaster response. Therefore, responders with year round heat acclimatization would be in a physiological state of readiness to work in hot and humid conditions. Such responders ought to be considered as preferred for deployment as part of the initial response team. For those responders yet to achieve heat acclimatization, the process can be commenced immediately in anticipation of deployment as part of the second response team. In this regard, individualized guidelines have been developed to assist medical responders and were utilized for the 2013 Typhoon Haiyan AusMAT response (13). These guidelines are highly relevant to Emergency Medical Teams () from temperate climates deploying to tropical regions.
Objective determination of responder heat acclimatization status requires a laboratory heat tolerance test () or field-based equivalent that is currently beyond the scope of AusMAT. However, active promotion of regular physical training for heat acclimatization ought to be considered as a prerequisite for members of Emergency Medical Teams with potential for deployment to the tropics. Where chronic heat acclimatization cannot be maintained, use of the pre-deployment guidelines will promote heat acclimatization to mitigate the risk of responder heat stress.
Statements
Author contributions
MB conceived idea for manuscript. MB, IN, and AT drafted and revised the manuscript.
Conflict of interest
The authors declare that this manuscript was developed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
References
1
BrearleyMHeaneyMNortonI. Physiological responses of medical team members to a simulated emergency in tropical field conditions. Prehosp Disaster Med (2013) 2:1–6.10.1017/S1049023X12001847
2
Geiger-BrownJRogersVETrinkoffAMKaneRLBausellRBScharfSM. Sleep, sleepiness, fatigue, and performance of 12-hour-shift nurses. Chronobiol Int (2012) 29:211–9.10.3109/07420528.2011.645752
3
BrearleyM. Cooling methods to prevent heat related illness in the workplace. Workplace Health Saf (2016) 64:80.10.1177/2165079915613353
4
LiXHouSZhengJFanHSongJ. Post-disaster medical rescue strategy in tropical regions. World J Emerg Med (2012) 3:23–8.10.5847/wjem.j.1920-8642.2012.01.004
5
SinclairWHRudzkiSJLeichtASFogartyALWinterSKPattersonMJ. Efficacy of field treatments to reduce body core temperature in hyperthermic subjects. Med Sci Sports Exerc (2009) 41:1984–90.10.1249/MSS.0b013e3181a7ae82
6
WalkerADrillerMBrearleyMArgusCRattrayB. Cold water immersion and iced slush ingestion are effective at cooling firefighters following a simulated search in a hot environment. Appl Physiol Nutr Metab (2014) 39:1159–66.10.1139/apnm-2014-0038
7
BrearleyMNortonIRushDHuttonMSmithSWardLet alInfluence of chronic heat acclimatisation on occupational thermal strain in tropical field conditions. J Occup Environ Med (2016) 58:1250–6.10.1097/JOM.0000000000000902
8
LorenzoSHalliwillJRSawkaMNMinsonCT. Heat acclimation improves exercise performance. J Appl Physiol (2010) 109:1140–7.10.1152/japplphysiol.00495.2010
9
SchladerZJSimmonsSEStannardSRMündelT. The independent roles of temperature and thermal perception in the control of human thermoregulatory behavior. Physiol Behav (2011) 103:217–24.10.1016/j.physbeh.2011.02.002
10
DellingerAMKachurSPSternbergERussellJ. Risk of heat-related injury to disaster relief workers in a slow-onset flood disaster. J Occup Environ Med (1996) 38:689–92.10.1097/00043764-199607000-00011
11
RogersBLawhornE. Disaster preparedness: occupational and environmental health professionals’ response to Hurricanes Katrina and Rita. AAOHN J (2007) 55:197–207.10.1177/216507990705500506
12
RusieckiJAThomasDLChenLFunkRMcKibbenJDaytonMR. Disaster-related exposures and health effects among US Coast Guard responders to Hurricanes Katrina and Rita: a cross-sectional study. J Occup Environ Med (2014) 56:820–33.10.1097/JOM.0000000000000188
13
BrearleyM. Pre-deployment heat acclimatisation guidelines for disaster responders. Prehosp Disaster Med (2016) 31:85–9.10.1017/S1049023X15005476
14
Amat CamachoNHughesABurkleFMJrIngrassiaPLRagazzoniLRedmondAet alEducation and training of emergency medical teams: recommendations for a Global Operational Learning Framework. PLoS Curr (2016) 8.10.1371/currents.dis.292033689209611ad5e4a7a3e61520d0
15
MoranDSErlichTEpsteinY. The heat tolerance test: an efficient screening tool for evaluating susceptibility to heat. J Sport Rehabil (2007) 16:215–21.10.1123/jsr.16.3.215
Summary
Keywords
acclimatization, disaster, emergency, heat stress, preparedness, responder, tropics
Citation
Brearley MB, Norton IN and Trewin AS (2017) The Case for Heat Acclimatization of Disaster Responders—An Australian Perspective. Front. Public Health 5:98. doi: 10.3389/fpubh.2017.00098
Received
16 March 2017
Accepted
11 April 2017
Published
25 April 2017
Volume
5 - 2017
Edited by
Bruria Adini, Ben-Gurion University of the Negev, Israel
Reviewed by
Ofer Merin, Shaare Zedek Medical Center, Israel
Updates
Copyright
© 2017 Brearley, Norton and Trewin.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Matt B. Brearley, matt.brearley@nt.gov.au
Specialty section: This article was submitted to Disaster and Emergency Medicine, a section of the journal Frontiers in Public Health
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