By Jamie Thompson
FireRescue1 Editor

AP Photo/Tim Larsen A firefighter takes a long drink from a bottle of water while fighting a five-alarm fatal fire in Burlington, N.J., in 2006.

Adequate hydration is key to firefighter health and safety. But accurately testing members' hydration levels on the fireground is no easy task.

That could change with the introduction of a portable, handheld device that can determine from a small sample of saliva whether a firefighter is sufficiently hydrated.

It could be available to fire departments from next year after developers of the technology, Cantimer Inc., were given a $996,000 contract by the U.S. Government's Technical Support Working Group (TSWG).

"We think this has the potential to save firefighters' lives," said Cantimer President & CEO Robin Stracey. "Being able to easily assess firefighters for dehydration, which has serious health consequences, will be a big step forward."

It's well known that more firefighters die of stress- and heat-related illnesses than from burns or injuries, and dehydration plays a major contributing role. Recommended fluid intake for the average person is about 2.4 liters a day. But research shows a firefighter in full turnout gear can lose a liter of water in 20 minutes of strenuous firefighting.

Decision-making abilities
Inadequate hydration compromises sweat production, Stracey said, and the subsequent rise in core temperature creates increased cardiovascular stress. Even moderate dehydration can take its toll — not just from a health standpoint, but by affecting decision-making abilities, too.

Calif.-based Cantimer first began work on the non-invasive hydration measurement and monitoring application about two years ago. Its efforts quickly attracted the attention of the TSWG, which has helped sponsor various fire service-related projects, including CBRN protective ensembles.

"They came out to visit us to take a look at what we were doing and were very excited about the potential, which led to the contract," Stracey said.

Researchers at the TSWG are currently testing prototypes in laboratory conditions with firefighters in full turnout gear. Cantimer, meanwhile, is working on a marketable version of the device aimed at firefighters which should be field tested next year.

Cantimer's hydration sensor consists of a tiny micro-cantilever embedded in a microscopic particle of a proprietary polymer. The polymer swells or contracts according to the concentration of the saliva, thereby generating movement in the micro-cantilever that can be detected with simple electronics.

The hydration sensor will be incorporated into a single-use disposable saliva collection cartridge that resembles a tongue depressor. Once the saliva sample has been collected, the cartridge will be inserted into a hand-held “reader” that displays the hydration measurement about 20 seconds later. From taking a saliva sample to delivering the hydration level, measurement takes a total of about a minute.

Current testing
Stracey estimates the device will cost about $300, and he hopes it will be commercially available by the middle of next year.

I am very excited about this technology and its potential ability to improve firefighter safety and fireground performance.

— Dr. Denise Smith Illinois Fire Service Institute

Current methods of testing hydration levels vary from department to department, ranging from measuring changes in body weight to the use of urine dipsticks and blood pressure monitors. There are more sophisticated measurement technologies available but they are generally impractical for use on the fireground.

"While there are a number of methods being used today to assess how hydrated or dehydrated a firefighter is, there is no single, universally accepted gold standard," Stracey said.

"Cantimer's device enables direct measurement of dehydration from a body fluid. It's non-invasive, takes only a minute, is easy to use, and, because of its size and low level of complexity, is field deployable.”

This ease of use belies the amount of research that has gone into the technology, according to Stracey.

"Designing the polymer to respond appropriately has been a real challenge," he said. "Saliva is a difficult sample —it's very complex — but we've come a long way and we are very excited by our progress. We genuinely think this technology can make a big difference in the health and wellness of firefighters."

Cantimer plans to collaborate on the TSWG project with Dr. Denise Smith, Ph.D., a professor in the Exercise Science Department at Skidmore College in New York. Her primary area of research is cardiovascular health, with a specific focus on the relationship between heat stress and cardiovascular function. Dr. Smith is also a Research Scientist at the Illinois Fire Service Institute at the University of Illinois.

"I am very excited about this technology and its potential ability to improve firefighter safety and fireground performance," she said. "We look forward to working with Cantimer to ensure that this technology is designed to be of greatest benefit to this country's first responders."