Vital Signs

Fundamentals of Nursing - Measuring Vital Signs

Physiology and Expected Ranges: Students will describe the physiology and expected ranges of vital signs.
Assessment Techniques: Students will describe the assessment techniques used to obtain vital signs.
Alterations Analysis: Students will analyze alterations in vital signs.
Nursing Interventions Planning: Students will plan nursing interventions in response to an alteration in vital signs.
Evaluation of Interventions: Students will evaluate the effectiveness of interventions to determine the extent to which client outcomes have been met.
Documentation: Students will demonstrate accurate documentation of vital signs.

Measuring and Recording Temperature: Demonstrate measuring and recording the body temperature of an adult and a child at oral, rectal, axillary, and tympanic (eardrum) sites using electronic or tympanic thermometers.

The five vital signs include:
- Temperature: Indicates the body heat status.
- Pulse: Reflects the heartbeat rate.
- Respiration: Monitors breathing function.
- Blood Pressure: Gauges the force of blood against the arteries.
- Pain Level: Recognized as the fifth vital sign.
Vital signs provide indications of the patient's health status and clues to changes in conditions.
Knowing age-variable normal values and physiological regulators is essential for accurate assessments.
Accurate measurements are required for reliable assessment and intervention.

Heat is a by-product of normal body metabolism.
As metabolism increases, heat production increases.
Infection or pathogen invasion leads to increased body temperature to elevate the basal metabolic rate (BMR), aimed at destroying pathogens.

Basal Metabolic Rate (BMR)
- BMR is influenced by thyroid hormones:
- Increased thyroid hormone levels cause a rise in metabolic rate and body temperature.
- Decreased thyroid hormone levels lead to a reduced metabolic rate and lower body temperature.
Other Hormones Influencing Metabolism:
- Epinephrine
- Norepinephrine
- Testosterone: Men generally have a higher BMR than women.
- Voluntary Muscle Movement: Increases heat production.
- Shivering: Can increase heat production up to five times normal levels.

The Hypothalamus functions as the body's thermostat.
Pyrogens (substances that cause fever) can elevate the thermostat's set point, leading to pyrexia (fever).
Responses to Temperature Changes:
- Decrease in body temperature results in peripheral vasoconstriction and shivering.
- Increase in body temperature prompts peripheral vasodilatation and diaphoresis (sweating).
Heat Loss Mechanisms: Heat loss occurs via skin exposure through:
- Radiation: Emission of heat away from the body.
- Conduction: Heat transfer through direct contact.
- Convection: Heat transfer to air or water around the skin.
- Evaporation: Loss of heat through sweat, resulting in approximately 800 mL of water loss per day.

Fever is defined as a body temperature higher than 100.2° F.
Pyrexia occurs when normal regulatory mechanisms cannot keep pace with the heat produced by the body, often due to pyrogens such as bacteria.
Diaphoresis: The excessive production of sweat is a cooling mechanism for the body.

Definition: The pulse is produced by cardiac contractions that generate a pressure wave against the walls of arteries.
The sinoatrial node initiates cardiac contractions.
Each contraction ejects approximately 60 to 70 mL of blood into the aorta (referred to as stroke volume), and:
- Cardiac Output: Cardiac output is calculated as:
  ext{Cardiac Output} = ext{Stroke Volume} imes ext{Heart Rate}
- The average cardiac output for an adult is approximately 5 L/min.
Determining Pulse: The pulse can typically be found using palpation or auscultation.
Strength of Pulse: This is determined by the force of cardiac contraction and circulating blood volume.
Factors Affecting Pulse Rate:
- Fever, pain, hypoxia, anxiety, exercise, and cardiac disease can alter the rate.
- The rate typically does not change with age, although dysrhythmias are more common in the elderly.

Definition: Respiration is an involuntary autonomic function controlled by the respiratory center located in the pons and medulla of the brainstem.
Respiratory rate is triggered by:
- Increased levels of CO2.
- Increased hydrogen ion concentration.
- Decreased levels of O2.
Organs of Respiration: The respiratory system includes:
- Nose
- Pharynx
- Larynx
- Trachea
- Bronchi
- Lungs
The respiratory center responds to feedback mechanisms, with carotid body receptors adjusting the rate and depth of respiration based on CO2 levels.
O2 and CO2 diffuse across capillaries in the lungs to maintain normal levels of these gases.

Definition: Blood pressure refers to the pressure exerted on arterial walls due to the heart's pumping action, influenced by:
- Condition of the vascular bed.
- Circulating blood volume.
- Cardiac output.
- Aging effects on blood pressure are considered normal.
Systolic Pressure: The pressure exerted on arterial walls during heart contraction.
Diastolic Pressure: The pressure during the resting phase between contractions.
Blood pressure is modified by changes in blood volume:
- Decreased blood volume can lead to a drop in pressure, often due to dehydration or hemorrhage.
- Vasoconstriction and vasodilatation mechanisms help maintain blood pressure based on circulating volume changes.

Temperature: Elderly individuals may experience increased heat loss, leading to potential hypothermia.
Metabolic Rate: A natural decline can contribute to hypothermia.
Respiratory Rates: May vary due to decreases in vital capacity with aging.
Blood Pressure: Systolic and diastolic pressures may increase due to arterial hardening.

Normal Body Temperature: Ranges from 97.5° to 99.5° F (36.4° to 37.5° C).
It is critical to understand the patient’s usual temperature for comparison when evaluating changes.
Variations by Site:
- Rectal temperatures are generally 1° F higher than oral temperatures.
- Axillary temperatures are usually 1° F lower than oral temperatures.
- Tympanic membrane measurements provide an approximation of core body temperature.