Chapter 26: Vital Signs

Chapter 26: Vital Signs

●       Vital signs reflect status of a person

○      Temp, pulse, respiration rate, blood pressure

●      The regulatory set point of the thermoregulatory center in the hypothalamus.

○      Receives cold and warm receptors located throughout the body.

○      With that information the temp set point, and responses to either produce or conserve body head or increase heat loss.

Heat Production

●      The primary source of heat in body is metabolism, product of metabolic activities that generate energy for cellular functions.

○      Additional heat is required to maintain balance, epinephrine, and norepinephrine are released to rapidly alter metabolism so that energy production decreases heat production increases.

●      Thyroid gland

○      Produces thyroid hormone

○      Increases metabolism and heat production

Heat loss

●      Skin is primary source of heat loss

●      Circulating blood brings heat to small connection betweenn arteriols and venuls

○      Called arterial shunts.

■      May open to allow heat to dissipate or may close and retain heat.

○      Sympathetic nervous system controls the opening and closing of the shunts in response to changes in core body temp and environment temp

●      Heat is transferred through radiation, convection, evaporation, and conduction.

●      Hypothermia-low body temp

●      Hyperthermia-high body temp

●      Afebrile-without fever

Increased body temperature

❖    Pyrexia (fever)- increase in body temperature

➢    Response to upward displacement of thermoregulatory set point in the hypothalamus, caused by pyrogens (cause fevers).

■      bateria/viruses can make this happen

➢    When thermostatic set point of hypothalamus is increased in response to pyrogen, the hypothalamus initiates temp-rising mechanisms: shivering, piloerections, vasoconstriction, increased metabolism.

❖    Treatment

➢    Bacterial or microbial infection an antibiotic or anti-ineffective may be prescribed.

➢    Antipyretic: aspirin, ibuprofen, or acetaminophen

➢    Cool sponge bath, cool packs, and cooling blankets

Decreased body temp

❖    Hypothermia occurs when compensatory physiologic responses meant to produce and retain heat are overwhelmed by unprotected exposure to cold environment.

➢    May have slurred speech, amnesia, hallucinations, and stupor

➢    Respirations decrease and the pulse becomes weak and irregular with lowering of bp.

Sites of temperature

❖    Most common is sublingual, under the tongue

➢    If patient has eaten hot or cold food or fluids wait 15 to 30 min to return to normal temp.

➢    Should not take oral temp is they have had surgery in nose or mouth or when there is a risk of seizures.

➢    Normal temps : 96.6-99.5

❖    Anal canal for rectal temp (most accurate core temp)

➢    Not used in newborns, children with diarrhea, or patients that have had rectal surgeries.

➢    Due to insertion, thermometer can slow heart rate by stimulating vagus nerve.

❖    Axilla (armpit)

➢    Normal readings: 96.5-98.5

❖    Tympanic (ear)

➢    Not used when patient has drainage, ear pain, ear infection, or scars on tympanic membrane.

➢    Maybe impacted by earwax

❖    Temporal (swiped over the skin covering temporal artery)

➢    If patient is lying on their side, measure only area exposed to environment.

➢    Do not measure over scar tissues, lesions, or abrasions.

Pulse

➔    Peripheral pulse is a throbbing sensation that can be felt over peripheral artery such as radial or carotid artery.

◆    Result from a wave of blood being pumped into the arterial circulation by the contraction of left ventricle.

◆    Heart contracts to eject blood into an already full aorta, smooth muscle in the arteries expands to compensate for increase in pressure of the blood.

◆    Rhythmic distention of the arterial walls is the result of surges of blood as the heart beats.

◆    Ther distention of the arteries move along the arterial system until it reaches the capillaries where vessel walls lack elasticity and peripheral resistance to blood flow

◆    Strength of pulse reflect the amount of blood ejected with each beat of the heart

➔    Apical pulse: listened over the apex of the heart as the heart beats.

◆    Characteried as lub-dub

◆    Mitral and tricusid “lub” and aortic and pulmonic valves “dub”

Physiology of Pulse

●      Regulated through autonomic nervous system through snioatrial node of the heart.

●      Paraympatheric stimulation of the SA node via the vagus nerve decreased the heart rate, and sympathetic stimulation of the SA node increases the heart rate and force of contraction.

○      Normal rate: 60-100 beats per minute

○      Tachycardia: rapid heart rate

■      Decreases cardiac filling time, decreases stroke volume and cardiac output, leading to decreased tissue perfusion.

○      Bradycardia: rate below 60 beats per min.

■      Can be normal in athletes and during sleep

○      Described amplitude: forceful, weak and thready when it is decreased in quality.

■      bounding=strong