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Temperature is a measurement of heat expressed in degrees. Body temperature may be defined as the degree of heat maintained by the body

Temperature means the degree of warmth or balance maintained between the heat produced (thermogenesis) and heat lost (thermolysis) in the body

Temperature is defined as measuring/monitoring patient’s body temperature using clinical thermometer

Types of Thermometers:

  1. Oral Thermometers:
    • These thermometers are placed under the tongue for temperature measurement.
    • It’s important not to eat or drink anything for a few minutes before using an oral thermometer to ensure accuracy.
  2. Rectal Thermometers:
    • These thermometers are inserted into the rectum for temperature measurement.
    • They are often used for infants and young children but require caution and proper hygiene.
  3. Axillary Thermometers:
    • Placed in the armpit, axillary thermometers are convenient for temperature measurement, especially in infants and young children.
    • They may take a bit longer to obtain a reading compared to oral or rectal measurements.
  4. Tympanic (Ear) Thermometers:
    • Tympanic thermometers measure the infrared radiation emitted by the eardrum.
    • They are quick and easy to use but may require proper positioning for accurate results.
  5. Temporal Artery Thermometers:
    • These thermometers use infrared technology to measure the temperature of the temporal artery on the forehead.
    • They are non-invasive and provide relatively quick results.
  6. Infrared Forehead Thermometers:
    • These thermometers measure the infrared radiation emitted by the skin on the forehead.
    • They are quick and non-invasive but may be less accurate than some other methods.


  • To determine body temperature
  • To assist in diagnosis
  • To evaluate the patients recovery from illness
  • To plan immediate nursing interventions
  • To evaluate the patients response
  • To recognize any variation from the normal and its significant


  • Routine part of assessment on admission for establishing a base-line data
  • As per agency policy to monitor any change in patient condition
  • Before, during and after administration of any drug that affects temperature control function
  • When general condition of patient changes
  • Before and after any nursing intervention that affects temperature of the patient

Normal Body Temperature for Adults

  • Oral: 37 degree Celcius or 98.6 degree F
  • Rectal: 37.6 degree Celcius or 99.6 degree F
  • Axillary: 36.4 degree Celcius or 97.6 degree F

The normal body temperature of a person varies depending on gender, recent activity, food and fluid consumption, time of day, and, in women, the stage of the menstrual cycle. Normal body temperature can range from 97.8 degree F (or Fahrenheit, equivalent to 36.5 degree celcius, or Celcius) to 99 degree F (37.2 degree Celcius) for a healthy adult. A person’s body temperature can be taken in any of the following ways:

Orally: temperature can be taken by mouth using either the classic glass thermometer, or the modern digital thermometers that use an electronic probe to measure body temperature

Rectally: temperatures taken rectally (using a glass or digital thermometer) tend to be 0.5 to 0.7 degrees F higher than when taken by mouth

Axillary: temperatures can be taken under the arm using a glass or digital thermometer. Temperature taken by this route tend to be 0.3 to 0.4 degree F lower than those temperatures taken by mouth

By ear: a special thermometer can quickly measure the temperature of the eardrum, which reflects the body’s core temperature (the temperature of the internal organs)

By skin: a special thermometer can quickly measure the temperature of the skin on the forehead

Body temperature may be abnormal due to fever (high temperature) or hypothermia (low temperature). A fever is indicated when body temperature rises about one degree or more over the normal temperature of 98.6 degree F, according to the American Academy of Family Physicians. Hypothermia is defined as a drop in body temperature below 95 degree F

Factors Influences Heat Production

  • Metabolism – oxidation of food
  • Muscle activity – exercise
  • Strong emotional – excitement, anxiety and nervousness
  • Change in atmospheric temperature
  • Disease condition – bacterial invasion
  • Sympathetic stimulation – epinephrine and norepinephrine


Normal (oral): 35.8 degree celcius to 37.3 degree celcius

Oral temperature: place the thermometer in the mouth under the tongue and instruct patient to keep mouth closed. Leave the thermometer in place for as long as is indicated by the device manufacturer

Axillary temperature: usually 1 degree celcius lower than oral temperature. Place the thermometer in patient’s armpit and leave it in place for as long as is indicated by the device manufacturer

Tympanic membrane (ear) temperature: usually 0.3 degree celcius to 0.6 degree celcius higher than an oral temperature. The tympanic membrane shares the same vascular artery that perfuses the hypothalamus. Do not force the thermometer into the ear and do not occlude the ear canal

Rectal temperature: usually 1 degree celcius higher than oral temperature. Use only when other routes are not available

Radial pulse: use the pads of your first three fingers to gently palpate the radial pulse at the inner lateral wrist

Apical pulse: taken as part of a focused cardiovascular assessment and when the pulse rate is irregular. Apical heart rate should be used as the parameter indicated in certain cardiac medications (e.g. digoxin). Apical pulse rate should be taken for a full minute of accuracy and is located at the fifth intecostal space in line with the middle of the clavicle in adults.

Carotid pulse: may be taken when radial pulse is not present or is difficult to palpate

Respiration rate: normal testing respiratory rate = 10 to 20 breaths per minute

Count respiratory rate unobtrusively while you are taking the pulse rate so that the patient is not aware that you are taking the respiratory rate. Count for 30 seconds or for a full minute if irregular

The average BP for an adult is 120/80 mm Hg, but variations are normal for various reasons

The systolic pressure is the maximum pressure on the arteries during left ventricular contraction

The diastolic pressure is the resting pressure on the arteries between each cardiac contraction

The patient may be sitting or lying down with the bare arm at heart level. Palpate the brachial artery just above the antecubital fossa medially. Wrap the BP cuff around the upper arm about 2.5 cm above the brachial artery

Palpate the radial or brachial artery, and inflate the BP cuff until the pulse rate is no longer felt. Then inflate 20 to 30 mm Hg more

Place the bell of the stethoscope over the brachial artery, and deflate the cuff slowly and evenly, noting the points at which you hear the first appearance of sound (systolic BP), and the disappearance of sound (diastolic BP).

Oxygen saturation (SpO2): a healthy patient will have a SpO2 of > 97%. A pulse oximeter sensor attached to the patient’s finger or earlobe measures light absorption of hemoglobin and represents arterial SpO2.

A visual analog scale (VAS) consists of a line, usually 10 cm long whose ends are labeled as the extremes of pain – ‘no pain’ to ‘worst pain’. A VAS may have specific points along the line that are labeled with intensity denoting adjectives or numbers. Those scales that use adjectives are called graphic rating scales. Patients are asked to rate their pain along the line that best represents the intensity of their pain. This distance between the no end and the mark provided by the patient is measured and this gives the pain intensity score

Factors Influences Heat Loss

  • Sleep: body temperature is low
  • Fasting: leads to decreased heat production
  • Illness and lower vitality: due to depressed nervous system, the heat production is lowered
  • Prolonged exposure to cold
  • Use of narcotic drugs

Body Heat is lost through

  • Conduction: transfer of heat from body to substance (air, water and cloths) directly in contact
  • Radiation: transfer heat from body to heat waves which travel through the space
  • Evaporation: transfer to heat from body in form of vapors (liquid is converted into vapors)
  • Convection: it is transfer of heat from the surface of one subject to the surface, such as skin by movements of heated air or fluid particles

Preparation of the Equipment

  • If a thermometer is included in the admission pack, keep it at the patient’s bedside and, on discharge, allow him to take home
  • Otherwise, obtain a thermometer from the nurse’s station or central supply department
  • If use an electronic thermometer, make sure it’s been recharged
  • Wipe the thermometer before use


  • Mercury or electronic thermometer, chemical dot thermometer, or tympanic thermometer
  • Water soluble lubricant or petroleum jelly (for rectal temperature)
  • Facial tissue
  • Disposable thermometer sheath or probe cover
  • Alcohol sponge

Common Sites for Taking Body Temperature

  • Mouth
  • Axilla
  • Groin
  • Vagina
  • Rectum


  • Oral method

Patients who are not able to hold thermometer in their mouth

Patients who may bite the thermometer like psychiatric patients

Infants and small children

Surgery/infection in oral cavity

Trauma to face/mouth

Mouth breathers

Patients with history of convulsion

Unconscious/semiconscious/disoriented patients

Patients having chills

Uncooperative patients

Patients who cannot follow instructions

  • Rectal method

Patients after rectal surgery

Any rectal pathology (piles/tumor)

Patients having difficulty in assuming required position

Acute cardiac patient

Patients having diarrhea

Reduced platelet count

  • Axillary method

Any surgery/lesion in axilla

Types of Thermometer

  • The clinical thermometer: it is an instrument used for measuring temperature of bodily heat or cold in which the mercury remain stationary at registration point until shaken down
  • Electronic thermometer: it consist of a battery powered display unit, a thin wire cord and a temperature sensitive probe covered by a disposable plastic sheath to prevent transmission of infection separate probes are available for oral and rectal insertion
  • Disposable thermometer: it is a single use thermometer, made of thin plastic strips with chemically impregnated paper, they are used for children to take oral and axillary temperature only 45 second are needed to record temperature it is less accurate
  • Tympanic membrane thermometer: small hold device similar to hodoscope with disposable speculum. Infrared-sensing electronic and liquid crystal displays. Results are displayed 1 to 2 seconds after placing their speculum in the outer third of the ear canal. It is accurate

Scales of Thermometer

  • Centigrade/Celcius: boiling point 100 degree and freezing point zero degree
  • Fahrenheit: boiling point 212 degree and freezing point 32 degree

Parts of Thermometer

  • A bulb contains mercury and in a stem, mercury rises. There is graduated scale on the stem, which represents the degree of temperature
  • The bulbs are of different sizes and shapes. The oral thermometers are with along and slender bulbs. The rectal thermometers are with short and fat bulbs
  • The stem has a curved surface which magnifies the lines and figures on the scale. The stem has a flattened back with a sharp ridge that makes is easier to read the scale. The flat surface prevents rolling

Reason for Mercury Used in the Thermometer

  • Very sensitive to small changes in temperature
  • Silver appearance helps in easy visible
  • It’s boiling point is 357 degree celcius ad freezing point is 39 degree F
  • The expansion of mercury is uniform
  • Mercury is 13.5 times heavier than water, so small glass tube can be used

Care of Thermometer

  • Grasp the thermometer securely by the upper end of the stem, never hold it by bulb
  • Shake it down by quick movements of the wrist
  • Move away from articles before shaking the thermometer
  • Be careful that the thermometer will not fall or strike against anything
  • Thermometer is never washed with hot water because heat expands the mercury
  • The used thermometer should be washed with soap and water and should be disinfected with a disinfectant
  • Advantages of using mercury are low price, wide availability and reliable accuracy
  • Disadvantages are delay for recording and easy breakability
TEMPERATURE & THERMOMETER - Purpose, Indications, Vital Signs, Measurement, Preparation, Equipment Common sites, Contradictions, Thermometer - types, scales, parts, care
TEMPERATURE & THERMOMETER – Purpose, Indications, Vital Signs, Measurement, Preparation, Equipment Common sites, Contradictions, Thermometer – types, scales, parts, care


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