How accurate are Tympanic thermometer than other types of Thermometer

How accurate are Tympanic thermometer than other types of Thermometer?

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A thermometer is an instrument with a defined scale used for determining the temperature of substances or bodies that vary their temperatures in different conditions. In principle, thermometers function by use of substance such as alcohol or mercury which has a physical property that varies with temperature and has some defined scale. Worth noting also is that thermometers vary based on different criteria, such include: axilla thermometer, Celsius thermometer, centigrade thermometer, clinical thermometer, electronic thermometer, Fahrenheit thermometer, oral thermometer, rectal thermometer and resistance thermometer among others.

Over the years, the mercury in glass thermometer has been used in measuring human temperature. However, due to various inefficiencies of the mercury in glass thermometers, digital thermometers, liquid crystal forehead thermometers and digital infrared tympanic thermometers have substituted the mercury thermometers. A tympanic thermometer is an electronic clinical thermometer that measures temperature by scanning the tympanic membrane (part of the ear that vibrates to sound). Usually, tympanic thermometers give digital readings in more than two seconds.

The reliability and the accuracy of these new thermometers have not been studied effectively thus in this paper, the main is to compare the accuracy of tympanic thermometers to other types of thermometers in measuring body temperatures. It will strive to clearly illustrate the advantages in terms of accuracy of tympanic thermometers over the other thermometers. The purpose of our study is to evaluate how accurate a tympanic thermometer is in measuring temperature and giving an exact reading about the same, in comparison to other thermometers.

Tympanic thermometers use infra-red light to detect thermal radiation (Woodrow, 2000).It is designed for intermittent use, offering a one-off digital reading. It is non-invasive, hygienic, simple to use, comfortable for the patient and quick to register (Bartlett, 1996). It is important to have strong background knowledge on the use of tympanic thermometers since its use requires proper handling and poor technique can lead to inaccurate temperature measurements. The thermometer should be gently placed in the meatus/ ear canal and allowed to fit snugly. This prevents ambient air at the opening of the ear canal from entering the ear thereby resulting to low temperature measurement. Other causes of false low reading can include incorrect installation of the probe cover, a dirty or cracked lens and improper technique. Proper maintenance by the electronic experts following manufacturer’s recommendations is also paramount.

In a research conducted by Fadzlin Mohd Fadzil, David Choon, and Kulenthran Arumugam, two hundred and seventy patients (youngest being six years old and oldest being eighty eight years old) randomly selected were used as specimens in conducting a research that aimed at evaluating the concordance in temperature amongst the three newer thermometers that is digital thermometers, liquid crystal forehead thermometers and digital infrared tympanic. The research further aimed at evaluating the accuracy of tympanic thermometer in relation to the others.

Patients were selected on days that nurses trained using the specified thermometers were on duty. Temperatures were taken using the four types of thermometers namely: mercury in glass thermometer (DMcare Clinical Thermometer), digital thermometer (DT-01[A]), liquid crystal forehead thermometer (Liquid Crystal Fever Temp Ultra®, DigiTemp), and digital infrared tympanic thermometer (Microlife IR 1DB1, Microlife). All the measurements were taken using manufacturer’s recommendation.

The mercury in glass and digital thermometers was used to measure oral temperatures and was put under the tongue of the patients (posterior sublingual pocket) with their lips sealed for three minutes prior to reading the results. The digital thermometer was left under the tongue until the device beeped. On the other hand, the non-disposable liquid crystal forehead thermometers were put on the patients’ forehead until the color stopped changing. A green color appearance indicated the correct temperature reading usually taking fifteen seconds.

The infrared tympanic thermometer was used to obtain temperature measurement by pulling the pinna upwards and backwards and inserting the probe into the external auditory canal. The probe was held in position until the device beeped usually taking a few seconds. For each measurement, a new probe is attached. All measurements were taken in degrees Celsius. In the event that there were doubts on the measurement, the nurses repeated the process. Apparently, ethical approval for the study was obtained from the Medical Ethics Committee, University Malaya Medical Centre.

In analyzing the research, the Bland Altman test was used. This is an explanatory diagnostic test between the two temperatures readings of each patient plotted on the Y axis against the means of the two temperatures plotted on the X axis. The mercury in glass thermometer readings were compared to the other thermometers tympanic thermometer being inclusive. The two parameters of interest are: the overall mean difference for the paired readings of each patient and the 95% limits of agreement for the paired readings of each patient. A value of zero indicates a perfect concordance. From the method, the tighter the limits of agreement, the better the concordance.

In assessing the concordance of two readings, Bland and Altman used the Statistical Package Version 9 for the analysis. From the analysis, the infrared tympanic thermometer was the next best with a narrower mean difference than the next best with a narrower mean difference than the digital thermometer. The results of the study show that in as much as the oral digital thermometer was the best, the infrared tympanic thermometer was a close second in terms of accuracy.

From the research, it was also evident that the infrared tympanic thermometers were easy to use and was recommended for use on uncooperative patients who weren’t comfortable with axillary thermometers. Although it was initially produced for home use, its efficiency and popularity found its way into hospitals and general practice clinics. In addition, the tympanic thermometer is considered to be fast in terms of temperature reading as compared to others with a min of two seconds.

In a different research by Gasim, Imad Musa, Mohamed T Abdien and Ishag Adams, the Infrared tympanic membrane thermometers are ideal because the tympanic membrane and the hypothalamus share an arterial blood supply originating from the carotid artery; therefore, the tympanic membrane is considered to directly reflect core temperature. An infrared tympanic membrane thermometer is usually easy to use and is favored over conventional mercury thermometer. The aim of their study was to compare temperatures obtained by tympanic thermometers with that obtained with mercury glass thermometers before recommending tympanic thermometers for use in general practice in Sudan.

The study was conducted in a hospital in Sudan including both children and adults. The study was approved by the ethical committee of Omdurman Hospital. Instruments used included the infrared tympanic membrane thermometer and the mercury bulb thermometer measuring the tympanic membrane temperature and axillary temperatures respectively. Trained medical officers and nurses conducted the investigations on patients who fulfilled the study criteria.

The probe of the infrared thermometer was inserted into the external auditory meatus by pulling the pinna backward, and directing the probe towards the eye. The probe was held in the same position until the beep was heard. The mercury bulb thermometer was shaken before each recording to decrease its temperature reading to below 35°C and then placed, for a minimum of 5 minutes, in the patient’s axilla. The same medical practitioners would read and record the digital readings from both the thermometers and analysis would be done using SPSS version 20.0 for Windows (SPSS Inc., Chicago, IL, USA).

Afterwards, differences between sets of data were plotted using the same Bland-Altman previously discussed in the earlier research. Based on the previously pre-defined clinically acceptable limits, agreement between tympanic and axillary measurement methods was accepted when the mean ± 2 standard deviations was within ± 0.2°C [15]. From the findings, there was a positive correlation between body temperatures using the two thermometers having a mean difference with limits of agreement between the two readings being−0.093 (−0.20; 0.02) °C.

Form the study, a positive correlation between axillary and tympanic methods of measuring body temperatures was discovered. This covered the question concerning how well the tympanic membrane temperature measurement corresponds with the standard axillary measuring procedure. It further explored the suitability of infrared tympanic membrane thermometers in replacing the axillary thermometers. It was discovered that the infrared tympanic thermometers takes seconds to measure temperature which was faster as compared to the other which took a considerably longer time, two to three minutes in measuring temperature.

Findings from this study further pointed out the fact that in as much as infrared tympanic thermometers are fast, doubts regarding their accuracy are evident in so far as differences being noted when measurement are made in both ears is concerned. Apparently, ear infections and improper use of the gadget have been given out as reasons behind difference in temperature. A further study comparing rectal temperature measurement with infrared tympanic thermometer measurement did not find excellent agreement of results.

However, Edelu et al., 2011 compared the infrared tympanic thermometer in oral mode with mercury glass thermometer readings for measuring the temperature in febrile and afebrile children less than years old, and found a mean difference of 0.41 ± 0.37°C (P < 0.001) in the febrile group and 0.47 ± 0.39°C (P < 0.001) in the afebrile group. Although tympanic membrane thermometers have a fairly good sensitivity and specificity, the study concluded that they may not be reliable in estimating ‘core’ body temperature in children

On the other hand, findings from the present study support the use of infrared tympanic thermometers since they are safe to use and are fast when it comes to obtaining results. In addition, the use of mercury thermometers has been considered a hazard in itself since mercury is toxic to human health. In effect, this has made infrared tympanic thermometers preferable to the old mercury glass thermometers. Others however would consider old mercury glass thermometers purely on cost but the infrared tympanic thermometers had an upper hand in terms of accuracy and reliability.

In this study, tympanic membrane thermometry was as reliable and as accurate as axillary mercury glass thermometry. Thus, tympanic membrane thermometry can be used in the general clinical practices, since it’s easy to use and its fast in generating temperature from patients. Tympanic thermometers are thus considered appropriate in measuring temperature for infants older than six months, children and adults. They are however not recommended for newborns. In operating a tympanic thermometer, it should be noted that its reliability and accuracy depends on several factors and aspects such as ear wax, curved ear canal and improper handling of the gadget can affect or interfere with the accuracy of its readings.

In conclusion, tympanic thermometers, which are also considered digital thermometers, are quite effective and they have replaced the old fashioned mercury bulb thermometers among others in measuring human body temperature. It is also important to note that the tympanic thermometers have pros and cons and their use should find a balance between the two before deciding on its usage. Finally, care should be taken as long as the gadget is on use so as to obtain an accurate and reliable result.

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