Figure. Shaking down a glass thermometer

"Crack the Whip." Shake the thermometer down using quick, sharp, downward wrist motions (figure). These quick wrist motions are sometimes called "cracking the whip." Perform several of these motions. You may have a problem getting effective "cracks" at first, but with practice you will soon be able to lower the temperature to the necessary level quickly.

Read the Thermometer. After shaking down the thermometer, read the temperature shown in order to evaluate the effectiveness of your efforts.

• If the thermometer reading is below 34.4º C (94ºF), you have shaken down the thermometer sufficiently.

If the thermometer reads 34.4º C (94º F) or above, continue to shake down the thermometer until a desired reading is shown.

T here is a risk of injury from cracking the original glass thermometers if too much force is applied by the teeth to hold them in place and the alcohol or mercury contents are poisonous.

This is avoided by the use of electronic thermometers which are made from solid plastic and use a metal (thermocouple) sensor.

A plastic thermometer strip placed on the forehead gives an approximate local reading, which depends to a great extent on ambient air temperature and local circulation effects.

A  plastic thermometer strip placed on the forehead gives an approximate local reading, which depends to a great extent on ambient air temperature and local circulation effects.

There are three principal locations for taking the patient's temperature: mouth, armpit, rectum (figure).

Figure. Three locations for taking temperatures

Mouth. A temperature taken by placing a thermometer in the patient's mouth is called an oral temperature. A thermometer designed for taking an oral temperature is called an oral thermometer.

Armpit. A temperature taken by placing a thermometer under the patient's arm in his armpit area is called an axillary temperature. A thermometer designed for taking oral temperatures is also used to take axillary temperatures.

Rectum. A temperature taken by holding a thermometer within the patient's rectum is called a rectal temperature. A thermometer designed for taking a rectal temperature is called a rectal thermometer.

W hat is the difference between an oral thermometer and a rectal thermometer?

Figure. Oral and rectal glass thermometers.

Glass Oral Thermometers

• The bulb of an oral thermometer is either long tipped, pear-shaped, or stubby (figure A). A long and slender bulb exposes as much surface area of the mercury as possible. Having more surface area exposed helps obtain an accurate temperature quickly.

• The other (stem) end of the oral thermometer is colored blue. Color-coding thermometers lets you tell an oral thermometer from a rectal thermometer quickly.

Glass Rectal Thermometers

• The bulb of a rectal thermometer is short and thick in order to protect the rectum (figure B). A long, slender bulb tip could accidentally injure the patient by penetrating the walls of the rectum. A blunt tipped thermometer is much less likely to damage the rectum. Remember, a thermometer with a long and slender bulb is definitely an oral thermometer while a thermometer with a short and thick bulb could be either an oral thermometer or a rectal thermometer.

• The stem end of a rectal thermometer is color-coded red.