Measure the Fever
Measuring fever means detecting body temperature.
The different thermometers have variable capacity to measure the internal temperature and to limit the possibility of errors during the detection, it is better to measure the temperature under constant conditions. Before proceeding with the detection of body temperature, for example, it is important to wait at least an hour after an intense physical exercise or a hot bath, and at least 20 - 30 minutes after smoking, eating or drinking a hot or cold liquid. Body points commonly used in the clinic to measure body temperature are: rectum, armpit and oral cavity . Some devices currently allow fever to be determined even in the ear or on the surface of the skin .
Each detection site has some advantages and disadvantages:
- Among the domestic surveys, the rectal temperature is the one that best represents the central temperature: the average measurement is 37 ° C with a maximum variation of plus or minus 0.5 ° C. The ambient temperature does not affect rectal measurements, which can be performed on patients of any age. However, these advantages are associated with an uncomfortable procedure and, for some subjects, embarrassing.
- The sublingual temperature is about 0.2-0.5 ° C lower than the rectal one. The procedure is simple and rapid, but accuracy can be compromised by taking hot and cold drinks or bradypnea, that is a decrease in the frequency of breathing (which is able to create a false temperature increase).
- The axillary temperature value is equal to 36.6 ° C ± 0.5 ° C, therefore slightly lower than the central temperature. In general, it is the most comfortable measurement for patients, but it is considered inaccurate as it is sensitive to the temperature of the environment. The most reliable temperature would be the lower esophageal temperature measured through special probes .
- For smaller patients it is possible to use the tympanic temperature measurement, which tends to be 0.8 ° C lower than the rectal value. The procedure is convenient, simple and uses infrared ear thermometers, which thanks to the special cone shape of the probe, can be inserted into the ear.
- The skin temperature is detected by devices that use infrared rays to detect the temperature of the forehead by contact or at a distance, using an optical pointer. However, their reliability is much discussed.
- At the hospital level, fever can be measured - through specialized equipment - also in other locations, such as bladder, in the pulmonary artery, in the nose-pharynx or in the esophagus.
Which thermometer to choose?
Until recently, mercury thermometers were the most widely used devices in medical practice, as they were precise and reliable, but since 2009 they have been banned from the Italian market because they are considered dangerous due to the potential toxicity of the liquid metal they contain (both for the patient in case of breakage, both for the environment in case of contamination).
Currently, several alternatives are commercially available:
- Digital thermometers are reliable, low-cost electronic devices. When an acoustic signal is heard, the temperature is shown on the display. They can be used rectally, orally and underarms.
- Infrared thermometers receive and process the IR radiation emitted naturally by the body, providing a rapid (about 10 seconds) and hygienic measurement. They point to the forehead or ear (earphone). The ear thermometer is easy to use, however it must be used correctly to provide a reliable and safe measurement.
- The thermometer in contact with galinstano is a glass device that contains an alloy of gallium, indium and tin inside the capillary. Galinstano has characteristics similar to mercury with regard to expansion at varying temperatures, but it is not toxic. It can be used both for rectal measurement and for that axilla. It is very precise and quite fast, but being glass it can break.
How to use a glass thermometer
Mercury or galistano thermometer
- Before measuring body temperature : hold the thermometer on the opposite side to the bulb. Rotate the thermometer until you see the red, blue or silver line (indicator). The liquid (mercury or galistan) contained in the internal capillary should be less than 35.6 ° C, so to make the indicator descend, the thermometer must be shaken several times (perhaps over a sofa or bed, to avoid breakage if it slips from the hand).
- Reading : remove the thermometer from the measurement site. Slowly turn the thermometer until you see the colored line at the thermometric scale, where each long sign equals 1 ° C, while the short lines correspond to 0.2 ° C.
How to measure the oral temperature
The sublingual temperature measurement allows the definition of fever in patients over 4 years of age. It is not recommended, in fact, to use a glass thermometer in a younger child, as it could bite the thermometer, and, if made of glass, break it in the mouth.
- Clean the thermometer with soapy water or alcohol and rinse. Do not smoke, eat or drink something hot or cold for at least 30 minutes before measuring the temperature;
- Place the probe under the tongue, towards the back and gently close the lips around the thermometer. If the mouth remains open it can determine inaccurate values;
- Breathe through your nose and use your lips to hold the thermometer firmly in place for 3 minutes or until the digital device beeps.
How to measure rectal temperature
Rectal temperature is recommended in children under 3 years of age or in the elderly, as it provides an accurate reading of the internal temperature. This method is especially suitable for patients who are unable to keep a thermometer safely in the mouth (infants, children and the elderly).
- Clean the thermometer with soap and water or alcohol and rinse with cold water;
- Lubricate the thermometer bulb with a small amount of Vaseline;
- Place the baby with the belly facing down on a stable surface or on the back, with the legs raised towards the lap;
- After separating the buttocks, gently insert the end of the thermometer approximately 2 cm into the newborn (only the bulb) and 5 cm into the adult in the rectum. Never force the thermometer and be careful not to insert it too deeply;
- Hold the thermometer in position: hold the baby and the other hand on the thermometer with your hand to prevent it from accidentally penetrating further into the rectum. It is important that the patient remains immobile during the measurement to avoid accidents;
- After 3 minutes or after the beep, remove the device and check the reading.
How to measure axillary temperature
Axillary temperatures are not as precise as rectal or oral measurements, and these generally measure 1 degree lower than an oral temperature obtained simultaneously
- Always clean the thermometer before and after use with soap and water or alcohol. Rinse with fresh water.
- Place the tip of the thermometer in the hollow of the armpit, in contact with dry skin and keep the device with the arm pressed against the body (keeping the elbow against the chest).
- Wait at least 5 minutes before reading or until you hear a beep, making sure the tip of the thermometer is covered by the skin.
How to measure the tympanic temperature
The tympanic measurement is determined by an infrared thermometer, which must be placed correctly in the patient's ear so that the reading is valid. The value of the tympanic temperature may not be precise in children under 3 years (36 months) of age and can be distorted either by a wax plug or by inflammation. Furthermore, it is not appropriate to use an ear thermometer in case of ear pain, infection or if the patient was still recovering from surgery at the site.
- Hold the baby's head or ask the patient not to move the head;
- Place the end of the thermometer by gently pulling the ear and then releasing it immediately. Do not push or use force. The tip of the thermometer must not touch the eardrum;
- When the device beeps, remove from the ear.
