A thermometer is a device used to monitor temperature.
Purpose
A thermometer is used to establish a baseline on the admission of a patient to a health care facility, to detect any abnormalities from the normal state, and to establish if current medication is having the desired effect.
Temperature is recorded to check for pyrexia or monitor the degree of hypothermia present in the body. The body's normal temperature is 98.6°F (37°C). A fever is a temperature of 101°F or higher in an infant younger than three months or above 102°F for older children and adults. Hypothermia is recognized as a temperature below 96°F (35.5°C).
Description
A thermometer can be mercury, liquid-in-glass, electronic with digital display, infrared or tympanic, or disposable dot-matrix. It can be used in a clinical or emergency setting or at home.
A mercury thermometer consists of a narrow glass stem approximately 5 in (12.7 cm) in length with markings along one or both sides indicating the temperature scale in Fahrenheit, Centigrade or both. Mercury is held in a reservoir bulb at one end that rises when the glass chamber is placed in contact with the body. Mercury thermometers are not used in modern clinical settings.
Electronic thermometers can record a wide range of temperatures between 94°F to 105°F, (35°C to 42°C) and can be used orally, axilliary (under the arm), or rectally. They have temperature sensors inside round-tipped probes and can be covered with disposable guards to prevent infection passing from one patient to another. The sensor is connected to the container housing the central processing unit, and the information gathered by the sensor is then shown on the display screen. Some models have other features such as memory recall of the last recording and a large display screen for easy reading. The thermometer probe is placed under the arm, tongue, or placed in the rectum and held in place for a few seconds, depending on the model used. The device will beep when the peak temperature is reached. The time required for obtaining the reading is between a few seconds to thirty seconds.
A tympanic thermometer has a round-tipped probe containing the sensor that can be covered with disposable guards to prevent infection from one patient to another. It is placed in the ear canal for one second while an infrared sensor records the body heat radiated by the eardrum. The reading then appears on the unit's screen.
Digital and tympanic thermometers should be used in accordance with the manufacturer's guidelines.
Disposable thermometers are plastic strips that have chemicals impregnated in dots on the surface. They are sticky on one side to adhere to the skin and prevent slippage and are worn under the armpit. The dots change color at different times as the chemicals respond to the body heat. The temperature is readable after two to three minutes, depending on the manufacturer's guidelines. Some products are disposable, reusable, or can be used continuously for up to 48 hours. These devices are useful for children, and the temperature can be recorded even while the child is asleep.
Operation
The patient should be sitting or lying comfortably to ensure that the readings are taken in similar positions each time and that there is little excitement to affect the results.
The manufacturer's guidelines should be followed when taking a temperature with a digital, tympanic, or disposable thermometer. Dot-matrix thermometers are placed next to the skin and usually held in place by a sticky strip. With the tympanic thermometer, caregivers should ensure that the probe is properly inserted into the ear in order to allow an optimal reading. The reading will be less accurate if the sensor cannot accurately see the tympanic membrane or if the view is obscured by wax and debris in the ear canal.
A mercury thermometer can be used to monitor a temperature by three methods:
Axilliary.
Orally or sub-lingually. This method is never used with infants.
Rectally. This method is used with infants. The tip of the thermometer is usually blue-tipped to distinguish it from the silver tip of an oral/axilliary thermometer.
Pyrexia—A temperature of 101°F (38.3°C) or higher in an infant younger than three months or above 102°F (38.9°C) for older children and adults.
Rectally—By the rectum.
Sub-lingually—Under the tongue.
Before recording a temperature using a mercury thermometer, the mercury is shaken down by holding the thermometer firmly at the clear end and flicking it quickly a few times in a downward motion toward the silver end. The mercury level should be below 96°F (35.5°C) before taking a temperature.
The silver tip is placed under the patient's right armpit, with the arm clamping it in place against the chest. The thermometer should stay in place for six to seven minutes. During this waiting period, the remaining vital signs may be recorded.
When the time has elapsed, the thermometer is removed and held at eye level. The mercury will have risen to a mark that indicates the temperature of the patient.
To record oral temperature, the procedure is the same as the axilliary method, except that the silver tip of the thermometer is placed beneath the tongue for four to five minutes before reading.
In both cases, the thermometer is wiped clean and stored in an appropriate container to prevent breakage.
To record rectal temperature, a rectal thermometer is used and shaken down as described above. A small portion of a water-based lubricant is placed on the colored tip of the thermometer. With the infant lying on his back, the nurse holds him securely in place. The tip of the thermometer is inserted into the child's rectum no more than 0.5 in (1.3 cm) and held there for two to three minutes. The thermometer is removed, read as before, and wiped with an antibacterial wipe. It is then stored in an appropriate container to prevent breakage, as ingestion of mercury can be fatal.
Liquid-in-glass thermometers contain alternatives to mercury (such as alcohol) and are used in the same manner.
Maintenance
Many digital and infrared thermometers are self-calibrating. To ensure accuracy, mercury thermometers should be shaken down prior to every use and left in place for at least three minutes. They require careful storage to prevent breakage and require cleaning after each use to prevent cross-infection.
Currently, there is a nationwide initiative to ban the sale of mercury thermometers and blood pressure monitors. Health activists are concerned about mercury contaminating the environment after it has been disposed of. A mercury thermometer contains 0.7g (0.025 oz) of mercury; one gram of the substance can contaminate a 20-acre lake. Several states have banned the use of products containing mercury, and stores such as Wal-Mart, CVS, and Kmart have already stopped selling mercury thermometers. According to a study by the Mayo Clinic in March 2001, mercury-free devices can monitor information without compromising accuracy. In October 1999, the Environmental Protection Agency (EPA) advised using alternative mercury products to avoid the need for increased regulations in years to come and to protect human health and wildlife by reducing unnecessary exposure to mercury.
Health care team roles
Patients may ask questions about specific concerns they have regarding aspects of vital signs or a particular disease. The nurse can provide counseling on the prevention of illness or direct the person to their doctor.
The nurse should make the patient comfortable and reassure them that recording temperature is part of normal health checks and that it is necessary that their health be correctly monitored. Any abnormalities in the temperature must be reported to the medical staff.
Training
Staff should be given appropriate training in the device used in the clinical setting.
OTHER
"Eleven of the Nation's Leading Retailers and Manufacturers Give Mercury Fever Thermometers the Heave-Ho." Online article. 8 August 2001. <http://www.nurses.com/content/news/article.asp?DocID={1CDF3C1E-9521-11D4-8C66-009027DE0829}>.
"Getting the Right Reading with Thermometers." 8 August2001. <http://www.nurses.com/content/news/article.asp?DocID={BE5A4CA0-00ED-11D4-8C2D-009027DE0829}>.
"Rectal Thermometer Use." 8 August 2001.<http://www.healthsquare.com/mc/fgmc0922.htm>.
