A clinical thermometer is a special instrument used to determine body temperature. It is used to detect fever.
What is the clinical thermometer?
Nowadays, the mercury thermometer has been replaced by the digital thermometer. Its operation is carried out with the help of batteries. With the help of a clinical thermometer, the human body temperature can be determined. It is considered a medical instrument and belongs in every medicine chest. The first clinical thermometers were made by Daniel Gabriel Fahrenheit (1686-1736). However, since they were 60 centimeters long, they were difficult to use. Moreover, their measurement results were quite inaccurate. In 1867, the clinical thermometer was modified by the English physician Thomas Clifford Allbutt (1836-1925). With a length of 15 centimeters, it was easy to use and could also provide precise measurements of body temperature. The approximate size is still used in modern times.
Shapes, types and kinds
Several types of clinical thermometers are used. Thus, there are mercury expansion thermometers, digital clinical thermometers and infrared thermometers. The classic thermometer form is formed by the mercury thermometer. It works by expanding a relatively large amount of mercury inside a thin capillary. A glass spike is added to the capillary to allow the maximum body temperature to be displayed. As the temperature rises, the mercury in the thermometer rises as part of a temperature scale. After taking a temperature, the thermometer must be shaken to return it to its original position. However, there is a health risk if the toxic mercury leaks out. For example, it can evaporate at room temperature and cause severe poisoning if inhaled. Since 2009, mercury clinical thermometers may no longer be sold in the European Union. Nowadays, the mercury thermometer has been replaced by the digital thermometer. It is operated with the help of batteries. The thermometer is activated by pressing a button. The measurement ends when the body temperature stops rising after a certain time. The end of the fever measurement is signaled by a beep. The temperature value can be read on a digital display. Special digital ear thermometers are also used in hospitals. They enable the body temperature to be determined quickly inside the ear. However, the determination is not always accurate. Another variant is the infrared thermometer. Here, the infrared radiation emitted by the eardrum or forehead is measured. A special lens then records the radiation. To display the body temperature, the infrared radiation is converted into a temperature value. The measurement time is only a few seconds.
Structure and mode of operation
The principle of a clinical thermometer is based on the change of liquid, gaseous and solid substances. Depending on the level of temperature, it comes to the expansion of the contained measuring liquid. Basically, a clinical thermometer is composed of a digital display or scale, a reactive measuring liquid inside a vessel-like container and a probe. A sheath made of glass serves as the body of the thermometer. To be suitable for taking a temperature, the thermometer must have a measuring range of 35 to 42 degrees Celsius and a resolution of 0.1 degrees Celsius. Furthermore, it is important to record the maximum temperature obtained during the measurement. Different methods can be used to measure body temperature. The axillary measurement method in the armpit is particularly common. In this case, the patient clamps the thermometer under the arm in the armpit. Although this method has the advantage of being convenient, it is also considered inaccurate. In contrast, oral measurement in the oral cavity is more precise. However, the measuring tip must achieve good contact with the oral tissue. The measuring tip should be sublingual, i.e. below the tongue. However, neither hot nor cold food should be eaten before the measurement. Oral measurement is not suitable for patients suffering from cough and cold. The most precise method is rectal measurement in the anus. For this purpose, the patient inserts the tip of the thermometer into his anus. This method is the most accurate because it allows the fever to be measured inside the body.The temperatures determined are approximately 0.4 degrees Celsius higher than under the armpits or in the oral cavity. Rectal measurement has proved particularly useful for children and restless patients. Other methods of determining body temperature include measurement in the ear, in the groin area, or in the vagina.
Medical and health benefits
The clinical thermometer is exceedingly important for diagnostic purposes. For example, with its help, it can be determined whether the patient is suffering from fever or not. In addition, the body temperature can be determined relatively accurately, which provides information about the patient’s condition. In the early morning hours, the body temperature of a healthy person is about 36.5 degrees Celsius in the anus, 36.2 degrees under the tongue and 36.0 degrees in the armpit area. During the day, the temperature can then rise by about one degree. The maximum value is reached in the late afternoon. A clinical thermometer is used in cases of suspected fever and infectious diseases. A distinction is made in the measurement between an elevated body temperature, moderate fever and high fever. The fever is classified as moderate if the temperature is up to 39 degrees Celsius. On the other hand, if the body temperature rises to 39.1 degrees, we are talking about high fever. By regularly measuring the fever, it is possible, among other things, to recognize the typical course of certain diseases. This is important for diagnosis as well as the course of medical treatment.
