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Pain
Pain perception and management
Question | Answer |
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Nociceptors(Sensory pain receptors) | free nerve endings in the tissue that respond to tissue-injuring stimuli (noxious stimuli). |
Receptors that respond to noxious temperature changes (thermoreceptors), chemicals (chemoreceptors), or pressure (mechanical receptors) transmit a pain signal if the noxious stimuli are sufficiently strong. | |
Nociceptors or neurons responding to noxious stimuli | found in the skin, blood vessels, subcutaneous tissue, muscle, fascia, periosteum, viscera, joints, and other structures. |
Nociceptors are located on two types of peripheral nerve cells | (A-delta fibers and C-fibers) that are responsible for transmitting pain sensations from the tissues to the central nervous system (CNS). |
A-delta fibers | give rise to bright, sharp, well-localized pain that is immediately associated with the injury |
C-fibers | Slow-conducting C-fibers cause a second pain sensation that is dull, poorly localized, and persistent after injury. |
The difference between pain from A-delta and C-fiber activation | first versus second pain. For example, if a sharp object falls on your foot, a fast, sharp pain alerts you to the injury. |
This pain is caused by stimulation of the A-delta fibers. After removing the object from the foot, a burning, dull, aching sensation persists and is caused by stimulation of the C-fibers. | |
Signals carried by A-delta fibers and C-fibers travel along | fibers from peripheral tissues through the dorsal root of the spinal cord and terminate in the dorsal horn of the spinal cord. |
Signals communicate | with local interneurons (excitatory and inhibitory) and neurons with long axons (projection cells) that ascend to the brain by way of several crossed and uncrossed pathways.The spinothalamic tract appears is most important pathway for pain sensation. |
This crossed pathway is located | the white matter of the anterolateral quadrant of the spinal cord. |
The spinothalamic tract transmits sensations | of pain and temperature and crudely localized touch. The spinothalamic tract enters the brainstem and terminates principally in the thalamus, where other neurons convey the information to the sensory cortex. |
Descending in the lateral white columns, a third of corticospinal tract neurons terminate on neurons in the | spinal dorsal horn and modify afferent nociceptive information (i.e., allow the brain to pay selective attention to certain stimuli and to ignore other painful stimuli). This information from the brain can modulate pain perception. |
What is pain modulation | (enhancement and inhibition)all levels of the nervous system.Modulation at the peripheral nerve, spinal cord, brain sites influences pain perception. |
capacity for modulation explains | the tremendous variability in pain that people wit similar injuries experience |
What is Peripheral Modulation | Mechanical, chemical, or thermal events that injure tissue usually stimulate nociceptors. Injured cells and tissue-repair mechanisms release one or more chemical substances that bind to peripheral nociceptors and activate the nerve fiber |
spinal dorsal horn | complex processing of messages occurs, is one of the most important areas for pain modulation. |
Input to dorsal horn excitatory interneurons releases | substance P and glutamate, both of which have the potential to facilitate pain sensation |
Endogenous opioids | endogenous (produced by the body) opioids |
Exogenous | (administered to the person) opioids bind |
Three groups of endogenous opioids relieve pain: | enkephalin, endorphin, and dynorphin. |
Some sensory impulses that enter the spinal cord | produce a reflex response through motor neurons in the spinal ventral horn with fibers to a muscle near the pain site. The muscle then contracts in a protective action (e.g., a pinprick causes immediate withdrawal of the extremity) |
These spinal reflexes may enhance pain through an effect on the injured tissue. For example, trauma may provoke an efferent (motor) reflex that produces muscle spasm in the injured area and causes more pain. | |
The gate control theory | when the gate is open(pain impulses flow through and the person feels pain) gate closed(pain impulses stop)Opening the gate is influenced by A-delta and C-fibers,closing the gate is influenced by the activity of the large A-alpha,A-beta fibers, the reticu |
dorsal horn cells act as a gate, closing to prevent nociceptive impulses from reaching the brain or opening to allow impulses to be transmitted to the brain. In simple terms, when the gate is open, pain impulses flow through and the person feels pain. | GCT emphasizes sensory, emotional, behavioral,cognitive dimensions of pain(playing role in modulation of the physiologic dimension) |
Characteristics of Pain | people describe pain by its location, intensity, quality, and temporal pattern. Sensory components of the pain experience are subjective but can be measured using standardized tools. |
Superficial pain | emanates from the skin or from tissues close to the surface is usually localized, and the client's pain location report matches the location of tissue damage |
When pain originates from internal organs | location the person reports may not be localized in area of tissue damage.(pain from the abdominal or pelvic organs(liver, spleen,kidney,bladder)may be referred to areas far distant from the site of tissue damage(not considered then misdirected therapy) |
Pain intensity | magnitude or amount of pain perceived. Terms used to describe pain intensity include none, mild, slight, moderate, severe, and excruciating. Pain intensity also may be described on a numeric scale (e.g., on a scale of 0 to 10 |
Pain Threshold | The amount of pain stimulation a person requires before feeling it( person's state of consciousness (i.e., under anesthesia) can dramatically change his or her pain threshold) |
Pain tolerance | highest intensity of pain that the person is willing to tolerate.some tolerate intense pain,some not(interventions) Endogenous pain modulation systems (facilitating or inhibiting the pain) may account for these differences. |
Pain Quality | how pain feels to client or words that describe the pain. When presented with a list of verbal descriptors, clients frequently use words such as those listed in Box 44-1. Without a list of descriptors, many clients find it easier to use an analogy |
Components of Temporal Pattern | Onset (when it starts) and duration (how long it lastspain all the time, incident pain (with movement or specific procedures), or breakthrough pain (returns before a regularly scheduled dose of analgesic). |
Pain pattern used for | determine the appropriate dosing schedule and medication preparation. Return of pain before the end of analgesic duration suggests the need for an increase in the drug's amount or frequency. |
Acute Pain | occurs abruptly after an injury or disease and persists until healing occurs. Acute pain also may be associated with anxiety and fear. Acute pain consistently increases at night and during wound care, ambulation, coughing, and deep breathing |
Chronic Pain(lasts for a prolonged period) | Associated with prolonged tissue pathology or pain that persists beyond the normal healing period.increases at night.Depression related to chronic pain is not uncommon.Frustration, fear are common feelings(clients experience when no cause is determined) |
Malignant Pain | is a third type, with recurrent, acute pain episodes, persistent chronic pain, or both associated with a progressive malignant-type process. |
Etiology for malignant pain | is resistant to cure, and the pain may be described as intractable |
Causes of Malignant Pain | arthritis or cancer. Like chronic and acute pain, malignant pain often increases at night.Clients with malignant pain often describe it as all-consuming and interfering with their quality of life. |
Newborns respond to pain with | increased sensitivity at birth with whole body movement.Within 3 seconds of a heel lance, the newborn begins to cry and cries for several minutes with a heart rate of about 50 beats/minute over baseline |
After Birth | large fibers become myelinated,endogenous pain inhibition develops.As infants develop more motor control, they try to pull or roll away from the pain and show general physical resistance.infant's responses influenced by reactions of parents |
Young toddlers and older toddlers | cannot identify the pain they are experiencing or its source. Older toddlers and preschoolers develop the ability to describe, identify, and locate sources of pain and can begin to use terms to define intensity and severity. |
Characteristics commonly associated with pain(important for this age group) | lethargy, fatigue, anorexia, and regression. |
School-Age Child and Adolescent | Children try to be “brave” and rationalize the pain.can identify pain's specific location, intensity, quality, and temporal pattern |
Adult and Older Adult | may ignore pain's normal warning function. Other adults may respond to the warning and take appropriate action, such as making lifestyle changes and getting a medical checkup. Fear of what the pain may indicate prevents some adults from taking action. |
Neural Plasticity | nervous system adaptation after pain |
Allodynia and hyperalgesia | types of dynamic nervous system plasticity (nervous system adaptation after pain). These abnormal sensations occur with tissue injury that leads to inflammation |
Allodynia | pain sensation produced by an innocuous stimulus such as light touch. |
Hyperalgesia | enhanced pain sensation produced by a noxious stimulus(Swallowing very hot fluid would produce hyperalgesic pain in inflamed pharyngeal tissue |
Read Page 1185 Sensitization | |
Suffering | emotional response associated with increased pain(pain and suffering are not same)Suffering(associated with events that threaten the person's intactness |
Pain is associated with | events that threaten tissue.People can suffer without pain.Assessments and treatments can be quite different. |
Clients with unrelieved pain often have concurrent emotional responses | anger, fear, anxiety, sadness, or depression, that can intensify pain perception. Emotions such as joy and pleasure may decrease the amount of pain perceived.Helping pt understand link between emotions and pain perception is important role for nurses |
Observable physiologic signs of acute pain include | Changes in blood pressure, heart rate, respiratory rate, and metabolic responses. Commonly observed responses in acute pain are usually absent in persistent and chronic pain because adaptation occurs(drug therapy lowers BP in the presence of severe pain) |
The increase in blood pressure that may accompany acute pain is believed to be due to | overactivity of the sympathetic nervous system.The increased blood pressure also increases the heart's work, possibly leading to coronary artery vasoconstriction and potential myocardial ischemia. |
Peripheral vasoconstriction is an adaptive response as blood shifts away | away from the periphery(skin, extremities)to the heart and lungs when the body perceives a threat. decreased peripheral circulation can be dangerous to pt undergoing vascular grafting procedures by diminishing blood flow needed to promote healing |
Increased heart rate | reflects the body's attempt to increase available oxygen and circulating fluid volume to promote healing of damaged tissues. |
Increased Respiratory Rate | effort to increase the amount of O2 available to heart and circulation. Unrelieved pain includes rapid and shallow breathing that is inefficient to meet oxygen needs which results in hypoxemia.(breathing is corrected with effective pain relief) |
Neuroendocrine and Metabolic Responses (Unrelieved pain produces a catabolic state).Stored energy is consumed to provide energy to vital organs and | injured tissue.known as the stress response,(capable of producing widespread metabolic effects)Some effects include generalized increase in metabolism, oxygen consumption, blood glucose, free fatty acids, blood lactate, and ketones.can last for days. |
Verbal behavioral responses to pain | most dependable indicators of pain in people who are able to communicate verbally.verbal reports indicate more clearly its location, intensity, quality, and temporal pattern |
Nonverbal Behavioral response to pain | often give a clue about pain location. include rubbing painful areas, frowns and grimaces, and increased muscle tension(body's fight or flight) that occurs with guarding and immobilization. |
Prolonged muscle tension | contributes to impaired muscle metabolism, muscle atrophy, and significantly delayed normal muscle function. |
The duration of pain Described | brief, momentary, transient, rhythmic, periodic, intermittent, continuous, steady, or constant. |
To measure onset | ask the client the date or time the pain started and how long it lasted. Assessing when the pain began (onset) is important in determining whether the client's pain is acute, recurrent, or chronic |
Memorial Pain Assessment Card (measures general mood), and the Brief Pain Inventory (measures pain interference with mood and activities | |
acute pain, the general responses observed include |