What is the central idea behind the Exergen Temporal Scanner?

Measuring the temperature inside, from the outside with medically accurate results without the invasive manner of standard thermometry. The central idea of Temporal Artery thermometry is to have a non-invasive skin thermometer with the accuracy of an invasive thermometer such as a catheter or rectal thermometer.

What physics are employed by the Temporal Scanner?

It starts with a skin temperature. Naturally emitted infrared radiation can provide a thermal signal to measure temperature in a fast accurate manner. Radiation detectors are available that can detect this, but there is a problem of emissivity to contend with, which is the characteristic of skin to emit different amounts of radiation at a given temperature. Using a technique originally developed for industrial use, the Exergen Temporal Scanner employs an emissive-correcting reflective cup within the scanning head. This corrects the emissivity automatically and eliminates all emission errors due to skin surface properties. The scanning head of the Temporal Scanner must be close to, or preferably lightly touching, the skin to work properly. The Exergen Temporal Artery Thermometer uses a thermistor embedded in the back of the probe to automatically measure ambient temperature. This controls for any affect on the skin from abient temperature. The computer in the Exergen Temporal Scanner then synthesizes the two temperatures to provide a core temperature as accurate as a temperature measured by a pulmonary artery or esophageal catheter.

Isn't skin temperature inaccurate? How does the Exergen Temporal Scanner work?

Yes, that is the reason there needed to be much more physiological insight for temporal artery thermometry to work. In a normal environment, skin temperature will always be significantly lower than body temperature. This happens because metabolic heat is generated inside the body and has to flow outside the body to the cooler ambient temperature, which it does so at the skin. If we knew the physiology of how heat is flowing from inside the core to the outside through the skin, and we knew the ambient temperature, we could determine the inside temperature. This determination is automatically performed by the arterial heat balance system (AHB) algorithm programmed into the Temporal Artery Scanner.

Can you scan anywhere on the skin or just the temporal artery using the Temporal Scanner?

No. Further physiology is required. The skin temperature is heavily influenced by the local blood perfusion, which can vary hugely due to thermo-regulation. The AHB algorithms require high and relatively stable skin perfusion to produce medically accurate body temperature. Research led to the superficial temporal artery (STA), which was found to lack arteriovenous anastomoses, an unusual property for a skin artery, effectively lacking valves which vary the skin perfusion. This meant that perfusion at the STA was essentially constant, and thus the AHB algorithms could produce medically accurate results. That an accessible part of the STA was located on both sides of the forehead above each eyebrow was especially convenient. There are some specific circumstances that produce high and stable skin perfusion that allow measurements in other locations, and users are instructed to use them when appropriate.

The superficial temporal artery is usually not visible. How does the Exergen Scanner find and measure it?

The STA is in a somewhat different location on each individual, which is the reason that TA thermometry employs a distinctive 'scan' of the forehead. The infrared detection system performs about 1000 measurements per second during the scan in a line across the forehead. Since the STA always traverses the forehead in a generally vertical direction, the scan across the forehead will always intersect the STA and detect the temperature of the skin over the STA. Of the several thousand readings in a scan, the AHB algorithm selects the peak reading, which is the most accurate, discarding the rest. Since STA at the forehead is always located between the skull and the skin, it is always very close to the skin surface, and a reliable temperature measurement can be made from newborns to seniors, allowing a single device to be medically accurate for all patients.

How is cost of the Temporal Scanner reduced by 90 percent?

This was one of the serendipitous benefits. Other medical thermometry systems require a probe to be inserted into a body cavity, which requires robust protection from contamination with a single-use disposable cover. The temporal scanner lightly scans the intact skin of the forehead, placing it in the same category as a stethoscope - simply clean between patients. The reduced use of disposable probe covers turns out to be a major benefit from TA thermometry, eliminating approximately 90 percent ofthe direct cost of providing this vital sign. This savings figure does not include labor time savings - reported at 87 percent of nursing time by a recent independent study - or the cost of disposal of several tons of waste per year. Further, since there is no small probe to be inserted into a body cavity, the Temporal Thermometer can be designed to be far more robust than conventional thermometers, and can carry a lifetime warranty. This not only eliminates direct repair costs, but also greatly reduces all of the indirect costs, such as removal of equipment from service, evaluation by biomedical engineering, return to the manufacturer, receipt of the repaired device and reinstallation to service. Since typical payback for temporal artery thermometry is measured in months, hospitals using TA thermometry have essentially eliminated the cost of patient temperature as a vital sign.

What effect does the Exergen Temporal Scanner have on caregiver-patient interaction?

This benefit was captured in an episode of the popular TV program Grey's Anatomy, depicting a physician gently scanning the patient with his personal Exergen Temporal Thermometer, while checking the patient's chart and joking amiably about his discharge. This interaction captures something unexpected and quite important - that the gentle touch of scanning the patient's forehead with a temporal artery thermometer evokes an emotional response of care given, and care accepted, from the caregiver and patient - the same as a mother's touch to the forehead of a sick child. This very much enhances the patient-caregiver experience, and is a significant reason why patients and caregivers are such strong supporters of the Temporal Artery Thermometer. TA thermometry every year eliminates nearly a billion probe insertions into patients' body cavities, replacing each one with a gentle touch of the forehead. This converts a billion unpleasant experiences for patients and caregivers to a billion very positive experiences for both - a major contribution to everyone's sense of wellbeing. Hopefully, soon the other five billion or so thermometry probe insertions per year will be converted as well.

How do oral temperatures differ from temporal artery scanning?

Oral temperatures are affected by patient activity such as mouth breathing, coughing, snoring, eating, drinking, etc. Oral temperatures can vary 2-3 degrees depending on the placement of the probe. Due to these resulting artifactual errors, oral temperatures can seriously mislead the clinician. The Exergen Temporal Artery Thermometer is not affected by any of these activities.