Vital Signs and Pain Assessment


The vital signs include assessment of temperature, pulse, respiration, and blood pressure. They are considered the baseline indicators of a patient’s health status.

Pain assessment is considered the fifth vital sign. Pain is a subjective unpleasant symptom of many conditions and injuries. The pain experience, its characteristics, and intensity are unique for each person. The Joint Commission (2017) requires healthcare facilities to make pain assessment and pain management a priority. Repeat assessment of pain is performed to evaluate the treatment response and to identify the presence of new or recurring pain.

Physical Examination Components

  • Temperature

  • Pulse rate

  • Respiratory rate

  • Blood pressure

  • Self-report pain rating scales

  • Assessing pain behaviors

  • Pain scales for children

Anatomy and Physiology

Vital Signs

Temperature

Body temperature is regulated and maintained by the hypothalamus. When pathogens invade the body, exogenous pyrogens—endotoxins produced by the pathogen—are released and travel to the hypothalamus. Pyrogenic cytokines are produced when phagocytic cells destroy microorganisms, leading to production of prostaglandin E 2 . The hypothalamus raises the body’s temperature set point, stimulating heat production and a fever (pyrexia). Release of epinephrine and norepinephrine increases heat production by raising the basal metabolic rate ( Huether and Rodway, 2019 ). Increased muscle tone and shivering, a rapid contraction and relaxation of the skeletal muscles, also produce heat. The body conserves heat by vasoconstriction, which reduces heat loss through the skin. Body cooling occurs through the skin by radiation, vasodilation, conduction, convection, evaporation, decreased muscle tone, and an increased respiratory rate.

Pulse Rate

The arterial pulse results when the ventricular heart contraction pushes a pressure wave of blood throughout the arterial system.

Respiratory Rate

The primary muscles of respiration are the diaphragm and the intercostal muscles. The diaphragm is the dominant muscle. It contracts and moves downward during inspiration to increase the intrathoracic space. The external intercostal muscles increase the anteroposterior chest diameter during inspiration, and the internal intercostal muscles decrease the lateral diameter during expiration. Air is drawn into the lungs during inspiration and expelled during expiration when the intercostal muscles and diaphragm relax, allowing the chest wall to recoil.

Blood Pressure

The arterial blood pressure is the force of the blood against the wall of an artery as the ventricles of the heart contract and relax. Systolic pressure—the force exerted when the ventricles contract—is largely the result of cardiac output, blood volume, and compliance of the arteries. Diastolic pressure is the force exerted by peripheral vascular resistance when the heart is in the filling or relaxed state. Blood pressure is highest during systole and falls to the lowest point during diastole. The pulse pressure is the difference between the systolic and diastolic pressures.

Pain

Pain is an uncomfortable sensation and emotional experience associated with actual or potential tissue damage. Acute pain is of short duration and has a sudden onset in association with injury, surgery, or an acute illness episode. Inflammation helps sustain the pain response. Persistent (chronic) pain lasts several months or longer and is often sustained by a pathophysiologic process (e.g., joint Disease, chronic inflammation, headache, or cancer). Neuropathic pain is long-term pain associated with damage or dysfunction of the central or peripheral nervous system (e.g., amputation, complex regional pain syndrome, diabetic neuropathy).

Nociceptors are free nerve endings in the peripheral nervous system activated by tissue damage from injury or inflammation. Biochemical mediators such as bradykinin, prostaglandins, serotonin, glutamate, and substance P facilitate the transmission of pain impulses from the nerve endings along nerve pathways. Pain impulses travel from the site of tissue damage to the dorsal horn of the spinal cord through the ascending spinal tracts to the thalamus and cerebral cortex. Two specialized nerve fibers transmit pain impulses (nociception) to the dorsal horn of the spinal cord. Sharp, well-localized pain is quickly transmitted by the large, myelinated A-delta fibers. Dull, burning, diffuse, and chronic pain is slowly transmitted by the small, unmyelinated C fibers ( Fig. 6.1 ). Specific spinal tracts transmit the pain signals to the brain where perception occurs.

Fig. 6.1, Transmission of pain impulses from pain receptors to the central nervous system.

After the pain impulses reach the spinal cord’s dorsal horn, the pain signal may be modified when other stimuli are present from either the brain or the periphery. Substances such as endorphins (endogenous opioids), and gamma-aminobutyric acid (GABA) can change or inhibit the pain perceived. Pain impulse transmission may be reduced when non-pain impulses (e.g., ice, massage) compete to transmit sensations along the same spinal pathways to the brain.

Response to pain is individualized because it is a physiologic, behavioral, and emotional phenomenon. Individuals have different thresholds at which pain is perceived and different pain tolerance levels. Emotions, cultural background, sleep deprivation, previous pain experience, and age are some factors that have an impact on a person’s perception and interpretation of pain.

Infants

Infants are more susceptible to hypothermia—low body temperature—because of their large body surface area for weight ratio, thinner skin, inability to shiver, and limited ability to cope with cold stress. Infants have a higher pulse rate and respiratory rate than adults, and the rates decrease as the child ages. Infants have a lower blood pressure than adults, and blood pressure increases as the child ages.

The nociceptor system for pain processing develops early in fetal life enabling preterm and full-term newborns to feel pain. The immaturity of the neurologic system results in some differences in pain transmission and processing. Most pain impulses are transmitted along the unmyelinated slower C fibers because myelination of the A-delta fibers continues to develop after birth. The transmission distance to the brain is short. Infants are less able to modify pain impulses due to immaturity of their dorsal horn synaptic connection and inhibition circuits in the descending spinal cord pathways. This results in greater sensitivity of the central nervous system to repeated painful stimuli (American Academy of Pediatrics, Committee on Fetus and Newborn and Section on Anesthesiology and Pain Medicine, 2016).

Pregnant Patients

Blood pressure commonly decreases because of lowered systemic vascular resistance beginning at about 8 weeks’ gestation, gradually falling until a low point is reached at mid-pregnancy. The diastolic value decreases more than the systolic value, and it gradually rises to prepregnant levels by term (Antony et al., 2017).

During pregnancy, some patients may experience pain due to several physiologic processes:

  • Back pain may be related to lax ligaments, weight gain, hyperlordosis, and anterior tilt of the pelvis.

  • Cramping or pressure may be signs of premature labor or Braxton Hicks contractions (sporadic uterine contractions that start at around 6 weeks of pregnancy).

  • Pressure from the gravid uterus may cause epigastric pain.

  • Round ligament pain may be due to the stretching of the ligaments by the enlarging uterus.

  • Pressure on the bladder may occur from the weight of the enlarging uterus.

During labor, pain may be related to dilation of the cervix, stretching of the lower uterine segment, and pressure on adjacent structures. During delivery, additional pain is caused by pressure of the fetal head against the pelvic floor, vagina, and perineum.

Older Adults

No evidence exists that older adults have a diminished perception of pain. However, some older adults may have an increased pain threshold or less pain tolerance associated with peripheral neuropathies, thickened skin, or cognitive impairment (Huether et al., 2019). Many have chronic health conditions associated with pain, such as arthritis, osteoporosis, or peripheral neuropathy.

Review of Related History

For each of the conditions discussed in this section, topics to include in the history of the present illness are listed. Responses to questions about these topics help to assess the patient’s condition and provide clues for focusing the physical examination.

Present Problem

Fever

  • Onset: date of onset, duration, cyclic nature, variability; related to injury or illness exposure

  • Associated symptoms: sweating, chills, irritability, nausea, vomiting, fatigue

  • Medications: acetaminophen or nonsteroidal antiinflammatory drugs (NSAIDs)

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