Fundamentals 29 Flashcards
Vital Signs
Indicators of health status, these measures indicate the effectiveness of circulatory, respiratory, neural, and endocrine body functions.
Assessment of Vital Signs
provides data to identify nursing diagnoses, implement planned interventions, and evaluate outcomes of care.An alteration in vital signs signals a change in physiological function and the need for medical or nursing intervention
Vital sign ranges for an adult
Acceptable Ranges for Adults
Temperature Range: 36° to 38° C (96.8° to 100.4° F)
Respirations
12 to 20 breaths/min
Average oral/tympanic: 37° C (98.6° F)
Average rectal: 37.5° C (99.5° F)
Average axillary: 36.5° C (97.7° F)
Blood Pressure
Pulse
Average: <80mmHg
Pulse pressure: 30 to 50mmHg
60 to 100 beats/min
When do you measure vital signs?
- On admission to a health care facility
- When assessing a patient during home care visits
- In a hospital on a routine schedule according to the health care provider’s order or hospital standards of practice
- Before and after a surgical procedure or invasive diagnostic procedure
- Before, during, and after a transfusion of blood products
- Before, during, and after the administration of medication or therapies that affect cardiovascular, respiratory, or temperature-control functions
- When a patient’s general physical condition changes (e.g., loss of consciousness or increased intensity of pain)
- Before and after nursing interventions influencing a vital sign (e.g., before a patient previously on bed rest ambulates or before a patient performs range-of-motion exercises)
- When a patient reports nonspecific symptoms of physical distress (e.g., feeling “funny” or “different”)
Use the following guidelines to incorporate measuring vital signs in the nursing practice.
The nurse caring for the patient is responsible for measurement of vital signs. Although you sometimes delegate measurement of selected vital signs (i.e., in stable patients), as a nurse you need to analyze them to interpret their significance and make decisions about interventions.
- Ensure that equipment is functional and appropriate for the size and age of the patient. Equipment used to measure vital signs (e.g., a thermometer) needs to work properly to obtain accurate findings.
- Select equipment based on the patient’s condition and characteristics (e.g., do not use an adult-size BP cuff for a child).
- Know the patient’s usual range of vital signs. These values can differ from the acceptable range for that age or physical state. The patient’s usual values serve as a baseline for comparison with later findings. Thus you are able to detect a change in condition over time.
- Determine the patient’s medical history, therapies, and prescribed medications. Some illnesses or treatments cause predictable changes in vital signs. Some medications affect one or more vital signs.
- Control or minimize environmental factors that affect vital signs. For example, assessing the patient’s temperature in a warm, humid room may yield a value that is not a true indicator of his or her condition.
- Use an organized, systematic approach when taking vital signs. Each procedure requires a step-by-step approach to ensure accuracy.
- Based on the patient’s condition, collaborate with health care providers to decide the frequency of vital sign assessment. In the hospital, health care providers order a minimum frequency of vital sign measurements for each patient. Following surgery or treatment intervention you measure vital signs more frequently to detect complications. In a clinic or outpatient setting you take vital signs before the health care provider examines the patient and after any invasive procedures. As a patient’s physical condition worsens, it is often necessary to monitor vital signs as often as every 5 to 10 minutes. The nurse is responsible for judging whether more frequent assessments are necessary (Box 29-2).
- Use vital sign measurements to determine indications for medication administration. For example, give certain cardiac drugs only within a range of pulse or BP values. Administer antipyretics when temperature is elevated outside of the acceptable range for the patient. Know the acceptable ranges for your patients before administering medications.
- Analyze the results of vital sign measurement. Vital signs are not interpreted in isolation. You need to also know related physical signs or symptoms and be aware of the patient’s ongoing health status.
- Communicate significant changes in vital signs to the patient’s health care provider or the charge nurse. Document findings and compare with baseline measurements to identify significant changes. When vital signs appear abnormal, have another nurse or health care provider repeat the measurement to verify readings.
- Instruct the patient or family caregiver in vital sign assessment and the significance of findings
Core Temperature
(temperature of the deep tissues) relatively constant, despite extremes in environmental conditions and physical activity
Thermoregulation
Physiological and behavioral mechanisms regulate the balance between heat lost and heat produced
Hypothalamus
located between the cerebral hemispheres, controls body temperature the same way a thermostat works in the home. Rise in temperature shuts the system down.
Anterior Hypothalamus
controls heat loss, and when nerve cells in the anterior hypothalamus become heated beyond the set point, impulses are sent out to reduce body temperature. Mechanisms of heat loss include sweating, vasodilation (widening) of blood vessels, and inhibition of heat production. The body redistributes blood to surface vessels to promote heat loss
Posterior Hypothalamus
senses that body temperature is lower than the set point, the body initiates heat-conservation mechanisms. Vasoconstriction (narrowing) of blood vessels reduces blood flow to the skin and extremities. Compensatory heat production is stimulated through voluntary muscle contraction and muscle shivering. When vasoconstriction is ineffective in preventing additional heat loss, shivering begins. Disease or trauma to the hypothalamus or the spinal cord, which carries hypothalamic messages, causes serious alterations in temperature control.
Basal Metabolic Rate(BMR)
accounts for the heat produced by the body at absolute rest and depends on the body surface area.
How do thyroid hormones affect BMR?
Thyroid hormones increase the rate of chemical reactions in almost all cells of the body by promoting the breakdown of body glucose and fat.
What happens when large amounts of thyroid hormones are secreted?
BMR can increase 100% above normal
What happens in the absence of thyroid hormones?
The BMR is reduced by half, causing a decrease in heat production.
Radiation
the transfer of heat from the surface of one object to the surface of another without direct contact between the two. As much as 85% of the surface area of the human body radiates heat to the environment.
Peripheral Radiation
increases blood flow from the internal organs to the skin to increase radiant heat loss.
Peripheral Constriction
minimizes radiant heat loss.
Conduction
the transfer of heat from one object to another with direct contact. Solids, liquids, and gases conduct heat through contact
How does the body gain heat?
when it makes contact with materials warmer than skin temperature (e.g., application of an aquathermia pad).
Convection
the transfer of heat away by air movement. A fan promotes heat loss through convection. Convective heat loss increases when moistened skin comes into contact with slightly moving air.
Evaporation
the transfer of heat energy when a liquid is changed to a gas. The body continuously loses heat by evaporation. Approximately 600 to 900mL a day evaporates from the skin and lungs, resulting in water and heat loss.
What happens when the body temperature rises?
the anterior hypothalamus signals the sweat glands to release sweat through tiny ducts on the surface of the skin. Sweat evaporates, resulting in heat loss. During physical exercise over 80% of the heat produced is lost by evaporation
Diaphoresis
visible perspiration primarily occurring on the forehead and upper thorax, although you can see it in other places on the body.
How much fluid is lost for each hour of exercise in hot conditions?
approximately 1L of body fluid is lost in sweat
What happens if the core temperature is too high?
the hypothalamus inhibits vasoconstriction. As a result, blood vessels dilate, and more blood reaches the surface of the skin.
What happens if the core temperature is too low?
the hypothalamus initiates vasoconstriction, and blood flow to the skin lessens to conserve heat
What does the ability of a person to control body temperature depend on
(1) the degree of temperature extreme, (2) the person’s ability to sense feeling comfortable or uncomfortable, (3) thought processes or emotions, and (4) the person’s mobility or ability to remove or add clothes. Individuals are unable to control body temperature if any of these abilities is lost.
Why are older adult particularly sensitive to temperature extremes?
because of deterioration in control mechanisms, particularly poor vasomotor control (control of vasoconstriction and vasodilation), reduced amounts of subcutaneous tissue, reduced sweat gland activity, and reduced metabolism.
Fever or pyrexia
occurs because heat-loss mechanisms are unable to keep pace with excessive heat production, resulting in an abnormal rise in body temperature. A fever is usually not harmful if it stays below 39° C (102.2° F)
Pyrogens
such as bacteria and viruses elevate body temperature. Pyrogens act as antigens, triggering immune system responses. The hypothalamus reacts to raise the set point, and the body responds by producing and conserving heat.
Afebrile
When the fever “breaks.”
Fever is an important defense mechanism.
Mild temperature elevations as high as 39° C (102.2° F) enhance the immune system of the body. During a febrile episode white blood cell production is stimulated. Increased temperature reduces the concentration of iron in the blood plasma, suppressing the growth of bacteria. Fever also fights viral infections by stimulating interferon, the natural virus-fighting substance of the body.
