What Is a Basal Thermometer?

The thermometer is a type of maximum thermometer, also known as "medical thermometer", Guangdong and Hong Kong and Taiwan areas are called heat probes. It can record the highest temperature ever measured by the thermometer.

Chinese name: thermometer
Foreign name: Medical thermomete

Management category: Class II medical devices
Category Name: thermometer

Thermometer principle

The working substance of the thermometer is mercury. Its glass bubble volume is much larger than the volume of the thin tube above. Due to the influence of body temperature, the mercury in the bubble causes slight changes, and the expansion of the volume of mercury causes a significant change in the length of the mercury column in the tube. The temperature of the human body varies between 35 ° C and 42 ° C, so the thermometer scale is 35 ° C to 42 ° C, and each range is divided into 10 parts, so the thermometer can be accurate to 1/10 °. When taking a reading, remove it from the armpit or mouth. The temperature of the glass bulb below it will decrease. In order for his reading to still represent body temperature, a special design must be made. This is the narrow tube between the glass bulb and the straight glass tube-the necking, as shown in Figure 1. The neck of the lower part of the thermometer near the bubble is a very narrow curved neck. When the temperature is measured, the mercury in the glass bulb expands with the temperature rise. It is squeezed through a thin tube to a straight tube and rises from the neck to At a certain position in the tube, when the thermal equilibrium with the body temperature is reached, the mercury column is constant. The outside air temperature is low, and the mercury shrinks when it is cold. It breaks in the narrow curved neck part, so that the mercury in the thin tube cannot return to the glass bubble, and still maintain the height reached when the mercury column contacts the human body, so it is separated The temperature still represents the temperature of the human body. After use, the thermometer should "return to the table", that is, holding the upper part of the thermometer and shaking it down vigorously, so that the mercury that has risen into the tube can be returned to the glass bubble. Other thermometers must not be shaken. This is a major difference between thermometers and other liquid thermometers. ^[1]

Figure 1 Mercury thermometer structure

Thermometer classification

Thermometer glass thermometer

The glass thermometer is the most common thermometer, it can keep the mercury column with the temperature rising, so that users can observe at any time. Because the structure of the glass is dense and the performance of mercury is very stable, the glass thermometer has the characteristics of accurate display and high stability. It also has the advantages of low price and no external power supply. It is deeply trusted by people, especially medical workers. However, the defects of the glass thermometer are also obvious, easy to break, there is the possibility of mercury pollution, the measurement time is relatively long, it is inconvenient to use for the critically ill patients, the elderly, infants, etc., and the reading is more complicated.

Electronic thermometer

With the development of science and technology, many types of new thermometers have appeared. The electronic thermometer uses the certain relationship between the physical parameters of certain substances (such as resistance, voltage, current, etc.) and the ambient temperature to display the body temperature in digital form, with clear readings and easy to carry. The disadvantage is that the accuracy of the displayed value is affected by factors such as the power supply of electronic components and batteries, and it is not as good as a glass thermometer. The electronic thermometer is composed of temperature sensor, liquid crystal display, button battery, ASIC and other electronic components. It can quickly and accurately measure human body temperature. Compared with traditional mercury glass thermometer, it has convenient reading, short measurement time and high measurement accuracy , Can memorize and have the advantages of beeping prompts. The electronic thermometer does not contain mercury and is harmless to the human body and the surrounding environment. It is especially suitable for use in homes, hospitals and other occasions. ^[2]

Thermometer Multifunctional Infrared Thermometer

The multifunctional infrared thermometer can measure ear temperature and forehead temperature. The dual function mode is suitable for measurement and use in different situations:

Figure 2 Ear thermometer measurement principle

Ear temperature. The thermometer is generally used in the armpit, mouth, rectum, etc. In practical applications, people generally feel inconvenient or uncomfortable. The ear thermometer measures the temperature of the human body in a non-contact manner by measuring the radiation brightness of the eardrum. The principle is shown in Figure 2. Just point the probe at the inner ear canal and press the measurement button to get the measurement data in just a few seconds. It is very suitable for patients with severe illness, the elderly, infants, etc. However, in the early stage of use, the user may not be familiar with this operation method, and may obtain several different measurement data. Generally speaking, the measured maximum value is the required data. The user will be more satisfied with this thermometer after being familiar with it. Babies within 10 months and users who have otitis media are more special. Because baby ears and ear canals are smaller and ear canals are more curved than adults within 10 months, ear temperature measurement is more difficult. Because otitis media has fluid in the ear canal, which can greatly affect the accuracy of the ear thermometer, users of otitis media are not suitable to use the ear thermometer.

Forehead temperature

Ear temperature and forehead temperature are measured by infrared, and the forehead temperature is reflected by the infrared radiation on the surface of the forehead and compared with the spectral temperature correspondence table to obtain accurate temperature values. There are also many infrared thermometers that also measure ear temperature and forehead temperature. Forehead temperature Collecting body temperature at the forehead is convenient, simple, and fast. A measurement time of a few seconds is usually sufficient and quite accurate. However, its professionalism is high, it is not convenient for popularization, and it is not suitable for home users. When the room temperature exceeds 25 degrees Celsius and the room temperature is less than 20 degrees Celsius, the thermometer is susceptible to environmental temperature, including sweating, air conditioning, etc. The acquisition temperature has a certain effect.

Clinical thermometer

New and evolving technologies have brought a very strange type of thermometer, called a sheet thermometer or a dot matrix thermometer. This thermometer is the size of a business card, 6-7 cm in length and 0.5 cm in width. It is covered with neatly arranged dots with numbers. After the temperature test is performed, all the dots below a certain value will be darkened, and the rest of the dots will not change color. The user can determine the body temperature based on the above changes. This kind of thermometer is not expensive, small in size, easy to carry and store, and has very little pollution. It is especially suitable for medical institutions and can be used once to avoid cross infection.

Thermometer "tablet type" internal thermometer

On March 14, 2019, researchers at Tohoku University in Japan newly invented a "tablet-type" internal thermometer, which can be discharged with the excrement, and has been successfully tested on dogs. This internal thermometer is about 9 mm in diameter and about 7 mm thick. It is the size of a tablet and contains a temperature sensor and a micro integrated circuit. The exterior is made of resin. It does not use a button battery that is harmful to the human body. Instead, it uses gastric acid contact electrodes to generate electricity and store it in a capacitor. It can measure body temperature and send data every 30 minutes.

Thermometer function

Basal thermometer is used to measure the basal body temperature of the human body just after waking up in the morning. Compared with daily body temperature, basal body temperature is less affected by environmental factors, such as exercise or eating. This helps to detect small daily changes in body temperature. For example, during ovulation or changes in thyroid function.

Glass fever thermometers have a minimum mark of 0.2 ° C; F (0.1 ° C), but basic thermometers need at least 0.1 ° C; F (0.05 ° C) accuracy. Therefore, the basic thermometer made of glass is sold separately from the general glass thermometer for fever. But all electronic thermometers have an accuracy of at least 0.1 ° C; F (0.05 ° C), so they can all be used as basic thermometers. Some digital thermometers are labeled as 'base thermometers' and have special features, such as a large display screen, additional memory functions, etc., or they can make a sound to guide the correct position.

Temperature measurement location

Oral cavity

Mouth temperature is collected by the patient's ability to place the thermometer correctly and safely in the mouth. That is, children or people who are unable to resist coughing, frailty, or vomiting are excluded (this is not a problem for fast-responding electronic thermometers, but it is an important issue in mercury thermometers because the mercury type The thermometer takes a long time to react to the temperature). The other thing to note is that if the patient has a hot or cold drink before using the oral thermometer, then other temperature measurement methods must be considered.

rectum

When taking rectal temperature measurements, especially when measured by another person, a lubricant should be used to help. Although rectal temperature is the most accurate, it is embarrassing to consider such behavior in some countries or cultures. In addition, if the thermometer is inserted incorrectly, the patient may feel uncomfortable or even painful. Babies usually use rectal temperature measurement, but it is more appropriate for them to be operated by a nurse.

In the ear or forehead

In addition, there are in-ear thermometers that measure the eardrum in the ear with infrared measurement technology, and forehead thermometers that measure the forehead.

Underarm

Before use, shake the mercury mercury of the thermometer below 35 ° C. Place the mercury end of the thermometer on the top of the armpit (the depth of the armpit), and clamp the thermometer with your upper arm to avoid dislocation or fall; measure for 5-10 minutes; remove the thermometer, read the temperature data, and wipe the thermometer with toilet paper For next time or for others to use.

Reading method: Hold the tail of the thermometer in one hand, that is, the end away from the mercury column, keep the eye and the thermometer at the same level, and then slowly turn the thermometer. When you see the thick mercury column from the front, you can read the corresponding temperature value. When reading, be careful not to touch the mercury end of the thermometer with your hand. This will affect the mercury column and cause inaccurate measurement.

Precautions:

1. If there is any sweat under the armpit, wipe it dry.

2. If the measurement time is not up and the armpit is loosened, it needs to be re-measured, and the time should be recalculated.

3. Before the temperature measurement, all factors that affect the actual temperature (such as drinking water or cold drinks) should be avoided. Drinking hot drinks, strenuous exercise, emotional excitement, and bathing should be measured after 30 minutes.

4. The maximum temperature value of the glass thermometer is 42 , so the temperature should not exceed 42 during storage or cleaning. Do not put the thermometer in hot water for washing or use to measure the temperature of water and other objects.

5. The glass thermometer is fragile and there is a possibility of mercury (mercury) pollution.

Thermometer breakage treatment

Mercury is a silver-white liquid metal with strong cohesion, so it will drop when scattered on the ground. If the cohesion is destroyed, it will become more small mercury droplets, which will not only make cleaning difficult, but also make it easier. Evaporation, if a mercury thermometer or mercury sphygmomanometer is damaged, it should be handled in the following order:

1. Non-related persons (especially children) other than the handling staff should stay away from the mercury-scattered area or room, keep the mercury-scattered area intact, and be careful not to step on the contaminated area.

2. Open the windows to ensure long ventilation in the room. It is best to turn on exhaust devices such as fans and ventilators at the same time to expel mercury vapor in the air.

3. Turn off heating appliances and other air-conditioning systems in the house.

4. Close the door to the contaminated room to isolate the contaminated room from other rooms in the house and prevent mercury vapor from spreading to other rooms.

5. Use a dropper, injection tube, bookmark, business card or plastic sheet, moistened cotton swab (such as a medical swab), tape, etc. to collect the mercury that has fallen on the ground, and then put the mercury into a sealable vial (such as Beverage bottle), add a small amount of water to avoid evaporation of mercury. Never use a vacuum cleaner or even heat mercury in any way (because it makes it easier to evaporate). Do not use a broom or any towel to handle or wipe the scattered areas, to prevent mercury from spreading. When collecting, keep your hands away from mercury. Sulfur powder can be sprinkled to reduce the toxicity of mercury that cannot be completely collected on the ground. ^[3]

6. The collected mercury should be stored in an airtight and sturdy container. Seal the bottle cap with tape and mark it. Items that are contaminated during the cleaning process (such as clothing, carpets, etc.) must also be placed in air-tight containers.

7. Use a flashlight near the scattered area to check whether there are small drops of mercury remaining. If there is still mercury, repeat steps 5-6.

8. Temporarily store the collected mercury and related contaminated items in a sturdy container outside the house, avoid contact with children and pets, contact the local environmental protection bureau or the cleaning team of the township and city office, and discharge it in the manner specified.

9. Continuously (for several hours) ventilate the contaminated room from the outside and isolate it from other rooms. If the room is contaminated with mercury, iodine and alcohol can be used to ignite fumigation, so that iodine and mercury in the air can synthesize hardly volatile mercury iodide. Mercury-contaminated floors can be washed with 10% bleach.

10. Do not pour collected mercury into the sewer to avoid contaminating groundwater sources. If mercury infiltrates the groundwater and people drink water containing heavy metals, it will endanger human health.