Fundamentals of Nursing | Chapter 24: Vitals

Flowchart nodes

• Physiology of Body Temp.

• Heat Production

• Heat Loss

• Metabolism: primary source of heat. 

• Heat is a byproduct of metabolic activities that generate energy for cellular activities.

• Physical Muscle Engagement  and hormones increase metabolism

• Short Term Hormonal Heat Production When additional heat is necessary, the body produces Epi and Norepi (sympathetic neurotransmitters) to rapidly  altar metabolism so that energy production decreases and heat production increases

• Long-Term Hormonal Heat Production Thyroid Hormone: increases heat production and metabolism

• Short Term Physical Response Shivering : Initiated by the Hypothalamus. Causes muscle tremors resulting in the production of heat. Causes the contraction of Pilomotor muscles, as occurs with shivering, and causes piloerrection, or goosebumps, which reduces the surface area of skin available for heat loss. Physical exertion increases heat production through muscle movement.

• Primary Site: The skin Mechanism: Circulating blood brings heat to skin surface

• Sympathetic Nervous System Controls

• Arteriovenus Shunts: connections between the arterioles and venules, close to the skins surface, which can open and close with signals from the SNS in response to core body temp changes and to external environmental changes in temp.

• Mechanisms of Heat Transfer

• Radiation: Diffusion or disemination of heat by electromagnetic waves Ex: Body gives off heat waves from uncovered surfaces.

• Convection: The dissemination of heat by motion between areas of unequal density Ex: an oscillating fan blows currents of cool air across the surface of a warm body

• Evaporation: the conversion of a liquid to a vapor. Ex: body fluid in the form of perspiration and insensible loss is vaporized from the skin.

• Conduction: The transfer or heat to another object during direct contact. Ex: The body transfers heat to an ice pack causing the ice to melt.

• Factors Affecting Body Temperature

• Circadian Rhythms

• Age and Gender

• Physical Activity

• State of Health

• Environmental Temperature

• 24 hour cycles of predictable events. Body Temp is 1-2 degree F lower in the morning than late afternoon and early evening. (this variation can be greater in infants and children )   Peak elevation occurs in late afternoon and early evening between 4 and 8pm

• Older adults lose thermoregulatory control with aging; body temps in older adults may be lower than the average adult temp. Older adults are at a higher rish of for harm from extreme temps due to impaired responses.      

• Infants' and Childrens' body temps change more rapidly in response to hot and cold air temps.

• Women tend to experience more changes in body temp fluctuations than men, due to changes in hormones. The increase in progesterone secretion at ovulation increases the body temp as much as .5-1 degree F.

• Exercise or physical exertion increases body temp via increased metabolism from increased muscle activity   Nurses should consider whether the patient has been exercising when taking vitals.

• Certain disease conditions and other health problems may result in alterations of body temperature.   See chart of Increased and Decreased Body Temperature.

• Hypothermia: low body temp. Can result from being in extreme cold too long. Can cause sudden illness or death.

• Hyperthermia: high body temp. Results from being in extreme heat too long. Can cause sudden illness or death

• Normal Body Temperature

• Average temp. varies among adults with a range of .5-1 degree F difference. Some adults have a wider normal range difference.

• Afebrile: means without fever

• Average Normal Temps @ Different Sites for Healthy Adults Oral:                          37.0°C     98.6°F Rectal:                       37.5°C     99.5°F Axillary:                    36.5°C     97.7°F Tympanic:                37.5°C     99.5°F Temp Artery:           37.0°C      98.6°F

• Increased Body Temperature

• Fever (pyrexia): being Febrile, an increase above normal body temperature. Is a signal of increased immune function and inflammation  

• Fever occurs in response to an upward displacement of the thermoregulatory set point in the Hypothalamus. This is caused by Pyrogens.

• Substances that trigger an increase in temp: -Bacteria -Bacterial products -Whole microorganisms (viruses)   Other Causes: -Chemicals produced in the body in response to tissue injury such as a MI, pulmonary embolism, cancer, trauma, and surgery.  

• Beneficial Effects (unless above 104°F, not usually harmful)   -Destruction of disease causing microorganisms -Increased susceptibility of disease-causing-microorganisms to anti-infective agents -Enhanced response by the immune system    

• Hyperpyrexia: dangerously high temp, 106° or above. Medical emergency, must be cooled rapidly to prevent brain damage

• Hypothalamus Response: -Pyrogens cause the hypothalamus to increase the set point of body temp. -Hypothalamus initiates temp raising mechanisms such as shivering, piloerection, vasoconstriction, and increased metabolism. -After the body temp reaches the new set point established by the hypothalamus, the body seeks to maintain this temp by providing heat-loss mechanisms such as sweating, vasodialation, and increased respirations.   Most fevers are self-limiting and the temp will return to normal after the factors causing it are controlled.        

• Onset and Significance of Fever from an Illness differs according to age.   -Children typically have more rapid progression of fevers than adults. -Infants younger than 3 months of age, do not have well developed temp controls, fever can be a sign of severe infection even with a mild elevation in temp. -Older adults have a lower base-line of temp therefore a fever may be one of the later signs of illness, with temp elevations of only slightly above normal, even with serious infection.

• Other Types of Fever:   -Hyperthermia: caused by extreme heat, not associated with a pyrogenic response of the hypothalamus. The set point of body temp is not changed. -Neurogenic Fever-result of damage to the hypothalamus from pathologies, or increased cranial pressure. This type of fever does not respond to antipyretic medications Fever of Unknown Origin (FUO): Temp of 101°F or higher that lasts for 3 weeks or longer without and identified cause.

• Physical effects of Fever: -Loss of appetite -hot, dry skin -flushed face -thirst -muscle aches -fatigue -Resps and pulse rate increases   -Young Children may have seizures -Older adults may have periods of delirium and confusion.   -Fever blisters may appear in some people as the fever activates Type I Herpes Simplex Virus   -Fluid, Electrolyte, and acid-base imbalances are potentially dangerous complications of fever.

• Treatment of Fever: -Must determine the cause of the fever, as the elevation in temp is one of the body's defense mechanisms. -Nursing focus for a fever is focused on patient comfort and preventing complications.   If Bacteria or Microbial has caused fever: -Antibiotics or antiinfectives may be prescribed. -Antipyretic or fever reducing drugs such as asprin, ibuprofen, or acetaminophen may be administered. These drugs reset the elevated set point regulated by the hypothalamus.

• It is suggested by many authorities of nursing that Asprin or products containing Asprin not be give to those 19 years old or younger during fever-causing or flu-like illnesses.

• Other treatments -Modifications of the external environment may be implemented to increase heat transfer from the internal to the external environment. Ex: cool sponge baths, cool packs, and cooling blankets. -Oral fluids are increased to maintain cellular and intravascular status and prevent dehydration. -Simple carbohydrates are included in the diet to prevent tissue breakdown from the hypermetabolic state.

• Decreased Body Temperature

• Hypothermia: a body temp  below the lower normal limit. It occurs when the compensatory physiologic responses meant to produce and maintain heat are overwhelmed by unprotected exposure to cold environments. Ex: accidental exposure, or impaired perception of cold.    

• Risks: -Chronic Conditions  such as alcoholism, malnutrition, and hypothyroidism, increase the risk of hypothermia. -Patients in the Perioperative Period and Newborn Infants are at increased risk of death. -Death may occur when body temps fall below 95°F, but survival has been reported in isolated cases such as falling into very cold water or being buried in snow. Survival is possible because rates of chemical reactions in the body are slowed thereby decreasing the metabolic demands for O2.

• Physical Effects: -Poor coordination -slurred speach -poor judgment -amnesia -hallucinations -stupor

• Treatment: Rewarming the patient -warm fluids administered either orally or through intravenous route

• Assessing Temperature

• -The Nurse must make sure to obtain and verify correct temp. -Glass or Mercury filled thermometers are not used and should not be recommended.    

• Types of Devices

• Electronic and Digital Used for Oral, Rectal, and Axillary body temp. over a time period from 1 to 60 seconds, depending on site and product used. Can automatically convert °C to °F Includes a full 60 sec pulse timer

• Tympanic Membrane Thermometers -Uses infrared sensors to detect heat given off by the tympanic membrane. -Uses probe covers that tightly seal the opening of the ear. -Takes 1 to 3 secs to read. -Doesnt touch the tymp membrane.

• Disposable single use thermometers -Non breakable and takes temp within seconds -Single use eliminates the danger of cross-infection -Temp. sensitive patches or tape are used and is commonly applied to the forehead and abdomen. They change color at different temp ranges.Mainly used in children  

• Temporal Artery Thermometers -Measures body temp by capturing heat emitting from the skin over the temporal artery. -Battery operated and have temp display. -More accurate and precise than those taken by the axillary and tympanic routes.

• Automated Monitoring Devices -Measure body temp, pulse, resps, and bp simultaneously.

• Sites and Methods of Assessing Body Temp

• Factors affecting site selection: -Patient's age -State of consciousness -Amount of pain -And other care treatmens such as O2 administration   If a temp reading is taken from a sight other than oral, it is important to document the site of measurment along with the result to ensure accurate comparison of data. If no sight is listed, it is generally assumed to be an oral temp. reading

• Oral Temp -The patient must be able to close their mouth around the probe. -the probe must remain in the sublingual pocket for the duration of the measurement. -If a patient has had either hot or cold food, has been chewing gum or smoking the general recommendation is to wait atleast 15-30 minutes to take an accurate reading. -Do not use oral cavity if the patient has an oral disease or who has had surgery in the nose or mouth -Do not use the oral route if a patient is recieveing an O2 mask because the time it takes to assess a reading is likely to result in a serious drop in the patients blood O2 level. -Oral temps range from 96.4°F to 99.5°F

• Assessing a Tympanic Membrane Temperature -Infrared sensor, doesn't touch the membrane -Site allows easy and safe reading and is readily accessable -Do not use in patients that have ear drainage, ear pain, ear infection, or scars on the tympanic membrane. -The readings are not significantly altered by cerumen or otitis media. -temps are approx. equal to oral temps.

• Assessing A Temporal Artery Tempature -Measured on the right of left side of the forehead is equally effective. -Do not take reading through any type of head covering or insulting materials. -If a patient is lying down, measure the side not in contact with bedding. -Do not take a reading over open lesions, scar tissue or abrasions. -move the thermometer slowly over the skin and remain in contact with skin during the duration of the measuement. -Temps measured here are approx. same as oral readings.

• Assessing Axillary Temp -May be used when oral and rectal sites are contraindicated, or when these sites are inaccessible. -place probe in axilla, hold patients arm by their side until complete. -Axillary temps are approx 1 degree lower than oral temp readings.