Urban search and rescue operations in tropical climates — ASN Events
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Urban search and rescue operations in tropical climates (#5)

Matt Brearley 1 , Ian Norton 1 , Michael Hutton 2 , Daryl Rush 3 , Steve Smith 3 , Hector Fuentes 4
  1. National Critical Care and Trauma Response Centre, Darwin, NT, Australia
  2. Northern Territory Fire and Rescue Service, Darwin, NT, Australia
  3. Queensland Fire and Emergency Services, Brisbane, QLD, Australia
  4. Princess Alexandra Hospital, Brisbane, QLD, Australia

Introduction
The physiological burden of long duration Urban Search and Rescue (USAR) operations in the tropics is poorly understood.

Methods
Sixteen trained USAR personnel (averaging 90.4kg, 1.81m, 39.6yrs) participated in a 24hr simulated exercise conducted during November 2013 in Northern Australia. Participants provided written informed consent for this study and were recruited from NT Fire and Rescue and QLD Fire and Emergency Services, resulting in 8 heat acclimatised (HA) and 8 non-heat acclimatised (NHA) responders. Physiological monitoring included core temperature through the use of ingestible thermometers based on established protocols1.

Results
The initial 4 hour shift (ambient 34.0oC, 48% relative humidity) resulted in 15 of the 16 participants exceeding the ISO98862 core temperature safe working limit of 38.5oC. From the 80th minute of the initial shift, HA sustained a significantly (p<0.01) higher core temperature (38.6oC) than the NHA cohort (38.1oC) despite both groups perceiving their body temperature equally as hot. Following the initial shift, only 2 participants exceeded a core temperature of 38.5oC, likely due to crews suffering from the heat strain endured during the first 4 hours. Seven (5 NHA, 2 HA) of the 16 participants presented to medical staff during this period with symptoms of headache, nausea and exhaustion.

Conclusion
Pacing of effort was apparent for non heat acclimatised personnel. Year round heat acclimatisation through physical training is likely to improve operational capability of deployed teams. More frequent rotation of crews to permit monitoring through a rehabilitation sector, inclusive of active cooling options, is also likely to reduce physiological strain and heat related illness during deployment to tropical regions. 

  1. Brearley MB, Heaney MF, Norton IN (2013). Physiological responses of medical team members to a simulated emergency in tropical field conditions. Prehospital and Disaster Medicine 28(2): 139-44
  2. International Standards Organisation (2008). Evaluation of thermal strain by physiological measurements (ISO 9886). [Standard] Geneva, Switzerland