or oral temperatures, you may choose either a glass or electronic thermometer. When using a glass thermometer, shake the thermometer down to 35°C (96°F) or below, insert it under the tongue, instruct the patient to close both lips, and wait 3 to 5 minutes. Then read the thermometer, reinsert it for a minute, and read it again. If the temperature is still rising, repeat this procedure until the reading remains stable. Note that hot or cold liquids, and even smoking, can alter the temperature reading. In these situations it is best to delay measuring the temperature for 10 to 15 minutes.
Rapid respiratory rates tend to increase the discrepancy between oral and rectal temperatures. In this situation, rectal temperatures are more reliable.
Causes of fever include infection, trauma (such as surgery or crush injuries), malignancy, blood disorders (such as acute hemolytic anemia), drug reactions, and immune disorders (such as collagen vascular disease).
If using an electronic thermometer, carefully place the disposable cover over the probe and insert the thermometer under the tongue. Ask the patient to close both lips, and then watch closely for the digital readout. An accurate temperature recording usually takes about 10 seconds.
For a rectal temperature, ask the patient to lie on one side with the hip flexed. Select a rectal thermometer with a stubby tip, lubricate it, and insert it about 3 cm to 4 cm (1% inches) into the anal canal, in a direction pointing to the umbilicus. Remove it after 3 minutes, then read. Alternatively, use an electronic thermometer after lubricating the probe cover. Wait about 10 seconds for the digital temperature recording to appear.
Taking the tympanic membrane temperature is an increasingly common practice and is quick, safe, and reliable if performed properly. Make sure the external auditory canal is free of cerumen. Position the probe in the canal so that the infrared beam is aimed at the tympanic membrane (otherwise the measurement will be invalid). Wait 2 to 3 seconds until the digital temperature reading appears. This method measures core body temperature, which is higher than the normal oral temperature by approximately 0.8°C (1.4°F).
The chief cause of hypothermia is exposure to cold. Other predisposing causes include reduced movement as in paralysis, interference with vasoconstriction as from sepsis or excess alcohol, starvation, hypothyroidism, and hypoglycemia. Elderly people are especially susceptible to hypothermia and also less likely to develop fever.
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