Body Temperature and Measurement Study Notes

Chapter 33: Publisher PowerPoint - Body Temperature and Measurement

Understanding Body Temperature

• Definition: Body temperature represents the heat produced by the transformation of food into energy.

• Heat Loss Mechanisms: The body loses heat through:

  1. Perspiration

  2. Breathing

  3. Elimination of body waste

• Balance of Temperature: The regulation of body temperature is maintained by balancing heat production and heat loss.

Influencing Factors on Body Temperature

• Conditions impacting body heat include:

  1. Metabolic Rate: Higher metabolic rates lead to increased heat production.

  2. Time of Day: Temperature is generally lower in the morning and higher in the afternoon and evening due to activity levels and metabolism.

  3. Activity Level: Physical activities raise body temperature as muscle metabolism increases.

Normal Body Temperature

• Normal Range: The average normal body temperature is around 37°C (98.6°F) but may vary:

  • Normal Oral Temperature:

  • Mean: 37°C (98.6°F)

  • Range: 36.5°C to 37.5°C (97.6°F to 99.6°F)

• Terms:

  • Febrile: Temperature is above the normal range.

  • Afebrile: Temperature is normal or subnormal.

Controlling Body Temperature

• Location of Regulation: The hypothalamus controls body temperature, acting like a thermostat to adjust temperature regulation via feedback mechanisms.

Hypothalamic Thermostat Mechanism

1. Thermostatic Function: The hypothalamus compares temperature data from peripheral (skin) and central (internal) receptors to assess body heat.

2. Heating and Cooling Processes:

   • When hot, the hypothalamus signals:

     • Sweat Glands: To secrete moisture, which cools the body upon evaporation.

     • Blood Vessels: To dilate, enhancing blood flow to the skin's surface for heat dissipation.

   • When cold, the hypothalamus signals:

     • Blood Vessels: To constrict, retaining heat.

     • Sweat Glands: To halt sweat production.

     • Muscle Tone Increase: Shivering occurs to generate heat.

Effects of Infectious Processes

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• Pyrogens Production: During infections, toxins from bacteria trigger pyrogens that lower the hypothalamic thermostat's set point, promoting heat production and conservation:

  • Symptoms of Infection: Chills, shivering, and increased temperature as the set point rises, which may vary based on the extent of the infection.

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  • Fever Classifications based on Severity:
    

    Classification	Fahrenheit	Celsius
    Slight	99.6-101.0	37.5-38.3
    Moderate	101.0-102.0	38.3-38.8
    Severe	102.0-104.0	38.8-40.0
    Dangerous	104.0-105.0	40.0-40.5
    Fatal	> 106.0	> 41.1
    Critical Temperatures: High temperatures exceeding 41.1°C (106.0°F) can lead to fatalities, depending upon duration and context.
    Measurement of Body Temperature

    • Measurement Tools: Various thermometers (Fahrenheit or Celsius) can be used to assess body temperature, including:

      1. Disposable thermometers

      2. Battery-operated electronic devices

      3. Tympanic infrared thermometers

      4. Temporal artery thermometers

    Thermometer Types Overview

    Type	Advantages	Disadvantages
    Plastic Disposable	Single use, rapid results, no cleaning required.	Unpleasant for patients, storage costs, must protect from heat.
    Electronic/Digital	Quick results, easy to read.	Initial costs, battery replacement expenses for some models.
    Tympanic Infrared	Fast results, noninvasive, good for all ages.	Can provide inaccurate readings if improperly placed.
    Temporal Artery	Instant results, very accurate alternative to rectal.	Needs to be acclimated to room temperature, may be expensive.
    Noncontact Infrared	Reduces cross-contamination risk, extremely user-friendly.	Measures surface skin temperature, may not represent core temp.

    Measuring Oral Temperatures

    • Method: Place thermometer sublingually for heat pocket measurement.

    • Preparations: Not measuring temperature if the patient has recently

      • Smoked

      • Consumed hot or cold beverages

    • Recording Temperature: Chart using the following example:

      • Example: 5/10/XX 11:30 am T. 99.8 B. DAVIS, RMA (AMT)

    Other Measurement Techniques

    1. Rectal Temperature: Most accurate, used for infants and children, indicated for certain medical conditions.

       • Normal rectal temperature = 37.5°C (99.6°F)

       • Not indicated for patients with rectal surgery.

    2. Axillary Temperature: Least accurate, good for compromised oral or rectal methods, normal axillary temperature = 36.5°C (97.6°F).

    3. Tympanic (Aural) Temperature: Averages 99.1-99.6°F; less invasive due to no contact with mucous membranes.

    4. Temporal Artery Temperature: Accurate, noninvasive, ideal for various patients, examples like infants and older adults.

    Temperature Conversion Equations

    • Celsius to Fahrenheit:
      $F = (C \times \frac{9}{5}) + 32$

    • Fahrenheit to Celsius:
      $C = (F - 32) \times \frac{5}{9}$

    • Example Conversion:

      • Convert 37°C to Fahrenheit:
        $37 °C \times \frac{9}{5} + 32 = 98.6 °F$

    Summary and Patient Education

    • Reporting Changes: Guide patients to inform health professionals of significant temperature changes.

    • Monitoring Temperature: Patients may need to be instructed on proper temperature measurement and reporting thresholds to seek further consultation.