Chapter 26: Vital Signs Flashcards

Overview of Vital Signs

Vital signs are fundamental indicators of a patient’s physiological status. These measurements must be accurate as they reflect the function of the body's most basic systems.

• Key Vital Signs:
  • Temperature ($T$)
  • Pulse ($P$)
  • Respiration ($R$)
  • Blood pressure ($BP$)
  • Pain (frequently regarded and documented as the fifth vital sign)
  • Pulse oximetry

Indicators for Assessing Vital Signs

Vital signs should be assessed at specific intervals or during certain clinical events to ensure patient safety and monitor health status:

• Upon admission to any health care facility or institution to establish a baseline.
• According to the specific policy and procedures of the facility or institution.
• Whenever there is a noticeable change in the patient's physical condition.
• If a patient experiences a loss of consciousness.
• Immediately before and after any surgical procedure or invasive diagnostic test.
• Before and after activities that might increase patient risk, such as ambulating for the first time after surgery.
• Before administering medications that specifically affect cardiovascular or respiratory functions.

Normal Vital Sign Ranges for Healthy Adults

• Oral Temperature: $35.8-37.5\,^{\circ}\text{C}$ ($96.4-99.5\,^{\circ}\text{F}$)
• Pulse Rate: $60$ to $100\,\text{beats/min}$ (Average is $80$)
• Respirations: $12$ to $20\,\text{breaths/min}$
• Blood Pressure: $< 120/80\,\text{mm Hg}$

Physiology of Body Temperature

Heat Production

• Primary Source: Metabolism is the primary source of heat production in the body.
• Metabolic Increases: Metabolism is increased by hormones, muscle movements, and physical exercise.
• Hormonal Control: Epinephrine and norepinephrine are released when the body requires additional heat, as they alter metabolism to increase production.
• Other Factors: Thyroid hormone and the physiological act of shivering likewise increase heat production.
• Process: Energy production decreases while heat production increases within the metabolic process.

Heat Loss Sources

• Skin: The primary source of heat loss from the body.
• Evaporation: Through the evaporation of sweat.
• Respiration: Through the warming and humidifying of inspired air.
• Excretion: Through the elimination of urine and feces.

Mechanisms of Heat Transfer

• Radiation: The diffusion or dissemination of heat by electromagnetic waves (e.g., heat lost from an uncovered head in cold weather).
• Convection: The dissemination of heat by motion between areas of unequal density.
• Evaporation: The conversion of a liquid (such as sweat) into a vapor.
• Conduction: The transfer of heat to another object via direct contact.

Factors Affecting Body Temperature and Fever Classification

Influencing Factors

• Circadian rhythms (daily biological cycles).
• Age and biological gender.
• Level of physical activity.
• Current state of health.
• Environmental temperatures.

Fever Terminology (Pyrexia)

• Afebrile: A state of being without a fever.
• Pyrexia/Febrile: A state of having a fever.
• Intermittent Fever: The body temperature returns to normal at least once every $24\,\text{hours}$.
• Remittent Fever: The temperature fluctuates several degrees up and down but does not return to normal.
• Sustained (Continuous) Fever: The temperature remains consistently above normal with only minimal variations.
• Relapsing (Recurrent) Fever: The temperature remains normal for one or more days, followed by one or more episodes of fever that can last several days each.

Temperature Assessment Tools and Site Normals

Equipment

• Electronic and digital thermometers.
• Tympanic membrane thermometers.
• Disposable single-use thermometers.
• Temporal artery thermometers.
• Automated monitoring devices.

Normal Values by Assessment Site (Adults)

• Oral: $35.9-37.5\,^{\circ}\text{C}$ ($96.6-99.5\,^{\circ}\text{F}$)
• Rectal: $36.3-38.1\,^{\circ}\text{C}$ ($97.4-100.5\,^{\circ}\text{F}$)
• Axillary: $35.4-36.9\,^{\circ}\text{C}$ ($95.6-98.5\,^{\circ}\text{F}$)
• Tympanic: $36.8-38.3\,^{\circ}\text{C}$ ($98.2-100.9\,^{\circ}\text{F}$)
• Forehead (Temporal Artery): $36.3-38.1\,^{\circ}\text{C}$ ($98.7-100.5\,^{\circ}\text{F}$)

Pulse

Physiological Regulation

• The pulse is regulated by the Autonomic Nervous System ($ANS$) through the cardiac sinoatrial ($SA$) node.
• Parasympathetic Stimulation: Decreases the heart rate.
• Sympathetic Stimulation: Increases the heart rate.
• Pulse Rate Definition: The number of contractions felt over a peripheral artery in $1\,\text{minute}$.

Characteristics of Peripheral Pulse

• Rate: Classified as normal, tachycardia (fast), or bradycardia (slow).
• Amplitude and Quality: Descriptive of the strength of the pulse (e.g., strong or weak).
• Rhythm: The pattern of the beats and intervals between them.
• Stroke Volume: The actual volume of blood ejected from the heart with each individual heartbeat.

Pulse Amplitude Grading Scale

• Grade 0: Absent; unable to palpate.
• Grade +1: Diminished; pulse is weaker than expected.
• Grade +2: Normal; pulse is brisk and as expected.
• Grade 3+: Bounding pulse.

Anatomical Sites for Palpation

• Temporal
• Carotid
• Brachial (Inner elbow)
• Radial (Wrist)
• Femoral (Groin)
• Popliteal (Behind the knee)
• Posterior Tibial (Ankle)
• Dorsalis Pedis (Top of the foot)

Respirations

Components of Respiration

• Ventilation: The physical movement of air in and out of the lungs.
  • Inhalation: Breathing in.
  • Exhalation: Breathing out.
• Diffusion: The exchange of oxygen ($O_2$) and carbon dioxide ($CO_2$) occurring between the alveoli of the lungs and the circulating blood.
• Perfusion: The exchange of $O_2$ and $CO_2$ between the circulating blood and the tissue cells.

Regulation of Breathing

• Respiratory centers are located in the medulla and pons of the brain.
• These centers are activated by impulses from chemoreceptors.
• The most powerful stimulant for respiration is an increase in carbon dioxide ($CO_2$) levels in the blood.

Respiratory Terminology

• Eupnea: Normal, unlabored respiration; typically follows a ratio of $1$ respiration to $4$ heartbeats.
• Tachypnea: An increased respiratory rate, often a response to an increased metabolic rate.
• Bradypnea: A decreased respiratory rate, which may occur in certain pathological conditions.
• Apnea: Periods during which no breathing occurs.
• Dyspnea: Difficult or labored breathing.
• Orthopnea: Changes in breathing patterns that occur when the patient sits or stands.

Blood Pressure ($BP$)

Definitions

• Blood Pressure: The force exerted by moving blood against the arterial walls.
• Systolic Pressure (Systole): The maximum pressure exerted when the left ventricle contracts and pushes blood through the aortic valve into the aorta.
• Diastolic Pressure (Diastole): The lowest pressure exerted when the heart is at rest between beats.
• Pulse Pressure: The numerical difference between the systolic and diastolic pressure measurements.

Regulation Mechanisms

• Short-term Regulation: Can be neural (nerve-based) or humoral (pertaining to body fluids).
• Cardiac Output: The strength and volume of heart contractions directly affect pressure levels.
• Neural Control: Vagus nerve stimulation (parasympathetic) slows the heart rate, while sympathetic stimulation increases it.
• Baroreceptors: Sensors in the heart and arterial walls that monitor pressure and signal the brain's cardiovascular center.
• Renin–Angiotensin–Aldosterone System ($RAAS$): A humoral mechanism that functions to raise blood pressure.

Influencing Factors

• Age and Race.
• Circadian rhythm.
• Biological sex.
• Food intake and Weight.
• Exercise and Body position.
• Emotional state.
• Drugs and medications.

Decreased Blood Pressure (Hypotension)

• Hypotension: Defined as a pressure $< 90/60\,\text{mm Hg}$. Often caused by disease, medication side effects, or a failure of homeostatic mechanisms.
• Orthostatic Hypotension (Postural Hypotension): An inadequate physiological response to position changes, specifically when rising to an erect position. Causes include dehydration, blood loss, or disorders of the neurologic, cardiovascular, or endocrine systems.

Assessment Equipment and Technique

• Equipment: Stethoscopes used with a sphygmomanometer (various cuff sizes available), Doppler ultrasound, or electronic/automated devices.
• Korotkoff Sounds:
  • The first sound heard is the systolic pressure.
  • The point where sounds change or cease is the diastolic pressure.
• Common Arteries: The brachial artery and popliteal artery are the primary sites for assessment.

Questions & Discussion

Question 1: What is the term for the heat that is lost when a person goes out in the cold without a hat?

• Answer: B. Radiation.
• Rationale: Radiation involves the diffusion of heat by electromagnetic waves, as seen with an uncovered head. Convection involves motion between unequal densities. Evaporation is liquid to vapor. Conduction involves direct contact.

Question 2: True or False: The normal pulse rate for adolescents and adults ranges from $60$ to $100\,\text{beats/min}$.

• Answer: A. True.
• Rationale: The standard healthy range for these age groups is $60$ to $100\,\text{beats/min}$.

Question 3: Which pulse site is located on the inside of the elbow?

• Answer: D. Brachial.
• Rationale: The brachial site is in the inner elbow. Temporal is the side of the head, radial is the wrist, and femoral is the groin.

Question 4: True or False: Changes in the rate and depth of inhalation and exhalation are brought about by the inhibition or stimulation of the respiratory muscles by respiratory centers in the medulla and pons.

• Answer: A. True.
• Rationale: The medulla and pons contain the primary respiratory centers that regulate the mechanics of breathing.