February 1, 2008 Industrial hygienists designed a flexible undergarment to take accurate readings of vital signs such as heart rate, breathing rate, and body temperature. They monitor these indicators to protect firefighters from overexertion and putting themselves in danger. The information can be sent wirelessly to a monitoring station for real-time monitoring.
Firefighting is a dangerous job, but the biggest risk doesn't come from the fire, smoke, or chemicals. Half of all firefighters who die in the line of duty suffer fatal heart attacks. Now, researchers are testing special gear that someday may alert others if a fellow firefighter is in trouble.
They risk their lives ý to save lives. But there's an invisible threat that puts them most at risk.
"Contrary to popular belief, firemen don't get burned, blown up or fall into holes. They die of heart attacks," Dave Hostler, Director of the Emergency Responder Human Performance Lab at the University of Pittsburgh, told Ivanhoe.
Firefighting is a physically demanding job. A firefighter may force his body to work at ninety-percent of its maximum heart rate for up to twenty minutes -- that's anywhere from 160 to 180 beats a minute.
"To somebody who is not in good shape, 160, 170 is a terrible stress," Hostler told Ivanhoe.
This specially designed vest has five built-in sensors that track vital signs. Inside the National Personal Protective Laboratory, researchers who study human performance want to know if this flexible undergarment called a lifeshirt takes accurate readings. How well does it track a firefighters body temperature, heart rate, and breathing?
Researchers put a volunteer through the paces wearing full firefighter gear. They monitor the signals from the sensors in his vest and compare them with measurements taken by the lab equipment.
"The signals would be sent back to a central command stations," Ron Shaffer, Director of the Research Branch of the National Personal Protective Laboratory, told Ivanhoe. A firefighter with a dangerously high heart rate could be pulled out of a fire. It's technology that could someday save the life of someone who works to save lives.
How does the heart use pressure to pump blood? The heart is a muscle, and when it contracts or beats, it pumps blood out. The heart contracts in two stages. First, the right and left atria contract at the same time to pump blood to the right and left ventricles. The ventricles then contract together to pump blood out of the heart.
The heart muscle relaxes before the next heartbeat to allow blood to fill up the heart again, since it must be filled with blood to pump. An average heart can pump 2.4 ounces of blood per heartbeat, or 1.3 gallons per minute. Your blood vessels act like pipes to carry the blood to and from the heart, distributing it through the body.
In order for blood to flow, it has to have a pressure difference, since blood -- like any other fluid -- flows from the high pressure to low pressure, just like a waterfall. That's why the pressure in the left ventricle is the highest, followed a slightly lower pressure in the left atrium. The pressure in the right ventricle is lower than the left atrium, but still higher than that of the right ventricle. So the left ventricle, with its high pressure, is able to push blood with sufficient force to send it through the body all the way down to the toes, with enough pressure left to bring it back to the right atrium and repeat the cycle.
The American Industrial Hygiene Association and the National Institute for Occupational Safety and Health contributed to the information contained in the video portion of this report.
Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.