As we head into a flu season where the 2009 H1N1 swine flu is expected to cause increased sickness, hospitalization and deaths across the U.S., something as simple as inaccurate body temperature measurements may lead to social and economic turmoil – and may cause many more deaths.
At the same time that reports estimate that half the U.S. population, or greater than 150 million people, may be affected by the flu this season and the Centers for Disease Control (CDC) recommends that people with influenza remains at home until at least 24 hours after they are free of fever, other reports have shown that approximately 40% of thermometer readings overestimate and 20% underestimate body temperature. The result is a perfect storm with 60% of Americans -- or 90 million people – receiving the wrong temperature readings during the flu season.
The consequences of these errors in temperature readings could have severe results. It can cause people who are sick to be falsely diagnosed as healthy, further spreading the flu virus. At the same time, healthy individuals can be falsely diagnosed as having fever and “forced” to remain at home. This can have a serious detrimental effect on our entire health care system and the economy as companies face shortages of healthy workers and consumer spending is curtailed.
Just sorting out which patients to treat and which to send home, for example, could strain our healthcare system. A recent report from the nonprofit Trust for America’s Health noted that if 33% of the population caught swine flu, 15 states could run out of hospital beds at the peak of the outbreak.
Businesses can be affected in two ways. Overall productivity will be reduced simply because there are fewer workers, and businesses that rely on customers, such as restaurants, movie theaters, malls and the travel industry, will be affected if more people, possibly millions, are not able – or willing, due to false fever readings – to go out. This will cause a ripple effect throughout the economy.
Children are particularly at risk because of their parent’s dependence on the only objective emergency warning sign, which is fever, according to the CDC. The other signs are subjective and difficult to interpret, such as fast breathing, not drinking enough fluids, bluish color or irritability. Therefore, wrong thermometry jeopardizes children in two ways -- lack of detection, which can lead to complications and possibly death; and false fever, which can expose them to the dangers of infections in a medical setting.
In addition, the military could be one of the greatest casualties of incorrect temperature measurements because they live in close quarters where disease can be easily transmitted. This was the case almost 100 years ago when the first wave of what became known as the 1918 flu pandemic appeared in military camps causing an enormous number of deaths.
BETTER TEMPERATURE MONITORING, BETTER CONTAINMENT OF DISEASE
Fever implies increased transmissibility, and a high fever that persists beyond three days is the only measurable flu danger sign and the key determining factor when someone should seek medical care. For people with underlying conditions, it’s important to be seen promptly if they have a high fever. According to CDC, that could make the difference between being severely ill and recovering well.
In a flu pandemic, precise temperature readings and accurate fever information are vital to make the right decisions. A new study from a research group at Yale University released today shows the reliability of temperature measurements from the body’s own natural temperature indicator using the Brain Temperature Tunnel (BTT), which transmits brain temperature to a small area of skin. The study, “Infrared Thermographic Analysis of Temperature on the Face, Forehead, Neck and Supero-medial Orbit,” is being presented today at the 2009 Annual Meeting of the American Society of Anesthesiologists in New Orleans, LA.
“Humans have invaded multiple orifices and penetrated multiple sites in an attempt to overcome the body’s thermal barriers to monitor core temperature,” said Dr. David G. Silverman, Director of Clinical Research and Professor in the Department of Anesthesiology and Critical Care Medicine at Yale University in New Haven, CT. “Our findings indicate that, all along, a tunnel to the organ most sensitive to -- and most responsible for -- body temperature has existed right between our eyes.
“The discovery of the BTT enables clinicians to escape dependence on invasive thermometry and surface measurements across thermal barriers,” he added.
CURRENT THERMOMETRY’S INABILITY TO OVERCOME THERMAL BARRIERS
As shown in this study, because the body’s fat layer provides insulation and prevents adequate thermal emission, the skin surface, such as the forehead and axila, cannot provide accurate thermal measurement. Forehead thermometers are thereby forced to rely on artificial calculations, which can lead to overestimation and underestimation. Ear canal thermometry also relies on artificial estimations, and numerous reports, including reports by the British Government, show the limitations and dangers of the errors caused by ear thermometers.
Rapid digital oral and rectal thermometry frequently rely on estimation techniques as well, leading to further inaccuracies. In addition, oral thermometry requires at least a 30-minute wait after food or liquid is consumed, otherwise the measurements will provide an erroneous reading. This is particularly problematic when consistent fluid intake, as recommended by the CDC, is vitally important for those recovering from the flu and to avoid complications. On the other hand, the BTT is not affected by food or liquid and the skin over the BTT is, surprisingly, fat free.
IMMEDIATE BENEFITS -- FEVER DETECTION AND MONITORING
“The resultant ability to achieve heretofore unavailable noninvasive one-time or continuous measurement of core temperature offers the immediate benefits of detection of fever and enables individual and population-wide monitoring of the prodromal, symptomatic and recovery phases for myriad disorders,” said Dr. Silverman.
“Wrong thermometry can cause social and economic turbulence during a pandemic,” said Dr. Marc Abreu, who originally identified the BTT and is one of the authors on the infrared emission study. “Nothing like these has affected the U.S. to this scale before. However, there is hope because we are all equipped by nature with a way to accurately read body temperature and fever -- in nature the threat, in nature the solution.