SINGAPORE: Singapore Civil Defence Force (SCDF) firefighters battling a raging industrial blaze can spend hours doing backbreaking work while enduring intense heat. Their body temperatures spike, not helped by the bulky protective equipment they have to wear.
These responders work in 30- to 40-minute shifts before rotating with another team. This is when they remove their gear, have a drink and rest under shade. But because they are so acclimatised to the heat, they might not realise their body temperatures have hit alarming levels.
Some can exceed 39.5 degrees Celsius, putting them at a higher risk of heat stroke. Left unchecked, heat injuries can have serious consequences, including multiple organ failure and death. The key is to reduce the body temperature as quickly as possible.
The SCDF wants to achieve this by rolling out a new purpose-built vehicle that can be deployed on scene to rehabilitate and treat first responders who show signs of heat injury. The Responders’ Performance Vehicle (RPV) was unveiled to the media on Wednesday (Aug 26).
“The RPV leverages on science and technology and we really would like to have this vehicle to improve our operations as well as the welfare and standards of our responders,” RPV project officer Captain (Cpt) Edrick Lim said.
The RPV comes with three types of cooling equipment for responders to dip their forearm or body in cold water. Studies have shown this technique is the quickest way of reducing temperatures, as compared to body cooling units, cooling packs and ice packs.
“They clearly state that in the event of heat stroke, where cold water immersion is available, it is the preferred mode of treatment,” said Major Dr Luke Tay, an SCDF operationally ready national serviceman (NSman) and consultant surgeon who was involved in the RPV project.
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The responders are sent to three sections based on their body temperatures: Rapid cooling zone (below 37.9 degrees Celsius), deep cooling zone (37.9 degrees Celsius and above), and cold water immersion (38.5 degrees Celsius and above).
Based on research, Cpt Lim believes the vehicle is the “first in the world” for combining three custom-built cooling methods on a single platform.
The SCDF has one RPV ready for deployment during prolonged incidents or those that come with a higher risk of heat exhaustion, including massive factory fires or chemical leaks. The latter require personnel to wear bulkier hazardous material suits.
SCDF chief medical officer Colonel (Col) Dr Shalini Arulanandam said the force could get a second RPV depending on its future training and operational needs, including how frequently the first RPV is used over the next few years.
The RPV, manned by a pair of paramedics and emergency medical technicians, is an improvement on SCDF’s Responders’ Performance Module. The latter, launched in 2013, is a 20-foot container with similar capabilities that had to be towed.
The module took 45 minutes to set up and could treat 20 personnel at once, compared to the RPV’s 20 minute deployment time and treatment capacity of 37 responders. The SCDF usually sends a first wave of 28 to 32 personnel to an incident.
RAPID COOLING ZONE
At a scene, responders’ temperatures are taken aurally before being sent to the RPV’s three zones. The vehicle is hooked up to a fire hydrant to fill an internal tank that chills the water.
The rapid cooling zone is located outside the RPV under a retractable shade. Fourteen foldable chairs, with hollow armrests containing 15 degrees Celsius water, are deployed on either side of the vehicle. Responders dip their forearms and sit under a vent that blows cool air.
This is a step up from the Responders’ Performance Module, which could only deploy eight chairs without immersion capabilities on either side. Fans were used instead of cool air.
Responders sit in these chairs for 20 minutes before their temperatures are taken again. Those who measure below 37.9 degrees Celsius can be re-deployed to the operation.
Cpt Lim said the science shows that 15 degrees Celsius water achieves the best balance between comfort and cooling rate, while body temperatures drop the most in the first 20 minutes.
DEEP COOLING ZONE
The higher-risk deep cooling zone is located inside the air-conditioned RPV, designed with darker colours and dimmer lighting to encourage mental recuperation.
There are two rows of four aluminium seats for optimal heat conduction. Responders again dip their forearms in 15 degrees Celsius water for 20 minutes.
The difference is that these armrests automatically fill with water, with the ability to maintain its temperature regardless of how much heat is dissipated. Machines continuously monitor a responder’s temperature, heart rate and oxygen level.
COLD WATER IMMERSION
Responders at the highest risk of heat injury, including those who show symptoms like disorientation, are sent for cold water immersion in a single fibreglass tub located outside the vehicle. Responders lie inside the tub in five degrees Celsius water.
The tub circulates and regulates the water at a consistent temperature throughout, and directs jet streams to different parts of the body to speed up heat removal. Responders are only submerged for five minutes due to the ice cold temperature.
The tub is also portable enough to be deployed outfield and in medical centres. Responders who undergo cold water immersion must be sent to hospital to be further assessed for heat injury.
The RPV was conceptualised in 2016 after the Responders’ Performance Module was shown to work during operations. It also built on an earlier predecessor called the Mobile Body Cooling Unit, which is an ambulance retrofitted with fans and pressurised water mists.
Over the next few years, SCDF studied the latest academic research, engineering solutions and medical science to come up with the RPV. The process involved SCDF NSmen doctors, National University of Singapore researchers and local engineering firm HOPE Technik.
SCDF said the RPV was designed and field tested with ergonomics and the user experience in mind. Responders including paramedics and emergency medical technicians tried out a prototype and gave feedback on its features.
“For example, things like dimensions and height of the cold water tub (and) making sure its corners are not sharp,” said Cpt Dr Arif Uzair Mohamad Roslan, an SCDF NSman who was also involved in the project.
“These are small things but played a major role in the eventual design of the tub.”
In the bigger picture, Col Dr Shalini said data from the RPV could be used to further study how responders physically react during operations.
“For vital signs collecting, we can deploy this RPV during training when they’re doing a live fire,” she said.
“We can monitor the trainees’ body temperature when they come out and after cooling. That’s very unique data that is not easily collected in a live situation without this vehicle.”