Introduction of Pain

Introduction of Pain

Pain is a predicted physiological response to an adverse chemical, thermal, or mechanical stimulus associated with surgery, trauma and acute illness. It is a difficult word to define. Patients use different words to describe pain e.g. aching, pins and needles, annoying, pricking, biting, hurting, radiating, blunt, intermittent, burning, sore, penetrating, piercing, etc. Pain is a universal human experience and the most common reason people seek medical care. Pain tells us something is wrong, that tissue in our body has been damaged, and we need to do something to change the situation. Because pain is such a strong motivator for action, it is considered one of the body's most important protective mechanisms. It is the most common reason for seeking health care.

Traditionally, pain was considered merely a physical symptom of illness or injury, a simple stimulus-response mechanism. Though the historic role of nurses has been to relieve pain and suffering, there has been little understanding of the complexity of pain and there has been only limited ways to manage it. Recent research shows pain to be a distinct disorder, with physical, emotional, and cognitive components.

Definition

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.

International Association for the Study of Pain 2011

The person who is suffering knows how the experience feels. For these reasons, Mc Caffery defined pain as "Whatever the experiencing person says it is and whenever he says it does (1979)." The American Pain Society goes further by stating that it is "not the responsibility of clients to prove they are in pain; it is the nurse's responsibility to accept the client's report of pain (2005)."

Nature of Pain

• Pain is, subjective, protective, and highly individualized.
• It interferes with personal relationships and influences the meaning of life.
• Only the patient knows whether pain is present and how the experience feels.
• Pain is a protective physiological mechanism e.g. a person with a sprained ankle avoids bearing full weight on the foot to prevent further injury.
• Pain is a warning that tissue damage has occurred.
• Pain is a leading cause of disability.
• The experience of pain is complex and it involves physical, emotional and cognitive component.

Qualities of Pain

• Organic vs. psychogenic
• Acute vs. chronic (daily for > 6 months)
• Malignant (indicating injury) or benign (harmless)
• Continuous or episodic

Sources of Pain

The sources of pain are divided into three main categories: nociceptor, non-nociceptor and psychogenic.

• Nociceptor pain results when tissue damage produces a pain-producing stimulus that sends an electrical impulse across a pain receptor (nociceptor) by way of a nerve fiber to the central nervous system. Nociceptor pain is further divided into visceral and somatic pain. Visceral pain results from stimulation of nociceptors in the abdominal cavity, and thorax. Somatic pain is divided into deep somatic and cutaneous pain. Deep somatic pain arises from bones, tendons, nerves, and blood vessels. Cutaneous pain originates in the skin or subcutaneous tissue. Some body tissues, such as the brain and lung, have no nociceptors and some tissues have many.
• Non-nociceptor (neuropathic) pain is caused by direct injury to structures of the nervous system.
• Psychogenic pain is pain for which there is little or no physical evidence of organic disease; however, lack of evidence does not mean the client is malingering and not suffering.

Physiology of Pain

Pain is a physiological response that warns us of danger. Though a person is not consciously aware of the process, the experience of pain involves a complex sequence of biochemical and electrical events or processes beginning with tissue damage, followed by transduction, transmission, perception, and modulation. There are peripheral nerve fibers and their receptor endings that monitor the stimuli for pain. The peripheral nerves carry the pain impulse to the spinal cord. In the spinal cord, pain is carried up to the brain via different pathways then the thalamus and cortex that integrate and modulate pain and finally the subjective reaction occurs.

The process of nociception describes the normal processing of pain and the responses to noxious stimuli that are damaging or potentially damaging to normal tissue. There are four basic processes involved in nociception (McCaffery and Pasero, 1999). These are:

• Transduction
• Transmission
• Perception
• Modulation.

Transduction of Pain: Pain is usually caused by thermal, chemical, or mechanical stimuli. The energy of these stimuli is converted to electrical energy. This energy conversion is known as transduction. Transduction begins in the periphery when the free nerve endings (nociceptors) of C fibers and A-delta fibers of primary afferent neurons respond to noxious stimuli. Nociceptors are exposed to noxious stimuli when tissue damage and inflammation occurs as a result of, for example trauma, surgery, inflammation, infection, and ischemia. The nociceptors are distributed in the:

• Somatic structures (skin, muscles, connective tissue, bones, joints).
• Visceral structures (visceral organs such as liver, gastro-intestinal tract).
• The C fiber and A-delta fibers are associated with different qualities of pain.

There are three categories of noxious stimuli:

•  Mechanical (pressure, swelling, abscess, incision, tumour growth)
• Thermal (burn, scald)
• Chemical (excitatory neurotransmitter, toxic substance, ischemia, infection).

All cellular damage caused by thermal, mechanical or chemical stimuli (noxious stimulation) results in the releases inflammatory chemicals, called excitatory neurotransmitters, such as bradykinins, histamine, a powerful vasodilator. These substances cause the injured area to swell, redden, and become tender. Bradykinin also stimulates the release of prostaglandins and substance P, a potent neurotransmitter that enhances the movement of impulses across nerve synapses. In order for a pain impulse to be generated, an exchange of sodium and potassium ions (de-polarisation and re-polarisation) occurs at the cell membranes. This results in an action potential and generation of a pain impulse.

Transmission of Pain: Transmission of the stimulus takes place when energy crosses into a nociceptor at the end of an afferent nerve fiber. The transmission process occurs in three stages. The pain impulse is transmitted:

• From the site of transduction along the nociceptor fibers to the dorsal horn in the spinal cord.
• From the spinal cord to the brain stem.
• Through connections between the thalamus, cortex and higher levels of the brain.

The pain fiber enters the spinal cord and travels one of several routes until ending within the gray matter of the spinal cord. Within the dorsal horn, substance P is released, causing a synaptic transmission from the afferent (sensory) peripheral nerve to spinothalamic tract nerves. Two types of peripheral nerve fibers conduct painful stimuli: the fast, myelinated A- delta fibers and the very small, slow, unmyelinated C-fibers. A-fibers send sharp, distinct sensations that localize the source of the pain and detect its intensity. C-fibers relay impulses that are poorly localized, burning, and persistent. For example, after burning a finger, a person initially feels a sharp localized pain as a result of A-fiber transmission.

Within a few seconds the pain becomes more diffuse and widespread, as a result of C-fiber transmission. Pain stimuli travel quickly to the substantia gelatinosa in the dorsal horn of the spinal cord where the "gating" mechanism (discussed later) occurs. Pain impulses then cross over to the opposite side of the spinal cord and ascend to the higher centers in the brain via the spinothalamic tracts and on to the thalamus and higher centers of the brain, including the reticular formation, limbic system, and somatosensory cortex.

Perception: A pain stimulus reaches the cerebral cortex, the brain interprets the quality of the pain and processes information from past experience, knowledge and cultural associations in the perception of pain. Perception is the point at which a person is aware of pain. When the painful stimuli are transmitted to the brain stem and thalamus, multiple cortical areas are activated and responses are elicited. These areas are:

• The reticular system: This is responsible for the autonomic and motor response to pain and for warning the individual to do something, for example, automatically removing a hand when it touches a hot saucepan. It also has a role in the affective-motivational response to pain such as looking at and assessing the injury to the hand once it has been removed from the hot saucepan.
• Somatosensory cortex: This is involved with the perception and interpretation of sensations. It identifies the intensity, type and location of the pain sensation and relates the sensation to past experiences, memory and cognitive activities. It identifies the nature of the stimulus before it triggers a response, for example, where the pain is, how strong it is and what it feels like.
• Limbic system: This is responsible for the emotional and behavioural responses to pain for example, attention, mood, and motivation, and also with processing pain and experiences of pain.

Modulation: The modulation of pain involves changing or inhibiting transmission of pain impulses in the spinal cord. Once the brain perceives the pain, the body releases neuromodulators, such as endogenous opioids (endorphins and enkephalins), serotonin, norepinephrine, and gamma aminobutyric acid. These chemicals hinder the transmission of pain and help produce an pain-relieving effect. The descending paths of the efferent fibers extend from the cortex down to the spinal cord and may influence pain impulses at the level of the spinal cord.

Types of Pain

There are different ways to define types of pain, which include nature of onset, duration. severity, modes of transmission, location, causation and causative forces.

• Onset or time of occurrence - postoperative pain
• Duration- chronic pain or acute pain
• Severity or intensity - severe, mild or scored (0 to 10 a scale)
• Location or source - superficial, deep or central pain
• Causation pain due to receptor stimulation or nerve damage or psychophysiological pain
• Causative force or agent - spontaneous, self-inflicted or other pain

Acute Pain

• It has a recent onset and is most commonly associated with a specific injury.
• It is episode of pain that lasts from a split second to six months.
• It is time limited and has a defined cause and purpose.
• It may be mild, moderate or severe in nature and sudden in onset.
• It occurs after an injury or disease, persists until healing occurs.
• It causes decrease healing, vital sign changes and diaphoresis.

Chronic Pain

• It is a complex physiological and psychological phenomenon that causes varying degrees of disability in a larger portion.
• An episode of pain that lasts for six months or longer.
• It is constant or intermittent in nature that persists over a period of time.
• It is often cannot be attributed to a specific cause or injury.
• It may last for six months or longer.
• It is classified as malignant or non-malignant.
• It causes fatigue, depression, immobility, anorexia, weight loss, apathy and anger.

Superficial Pain

• It occurs when receptors in surface tissues are stimulated.
• Classified into 2 types:
  •  Pain with an abrupt onset and a sharp or stinging quality.
  •  Pain with a slower onset and burning quality.
• It may be delineated by having the client point to the painful area.
• It is relatively uncomplicated because it is readily localized, that is, which client can indicate exactly where it hurts.

Deep Pain

• Deep pain arises from deep tissues.
• It is divided automatically into splanchnic which refers to pain in the viscera and deep somatic referring to pain in deep structures other than the viscera such as muscle, tendons, joints and periosteum.

Splanchnic Pain

• Viscera pain tends to be diffuse, poorly localized, vague, dull pain.
• Autonomic manifestations such as diarrhea, cramps, sweating, hypertension frequently accompany viscera pain.
• It includes acute appendicitis, cholecystities, inflammation of the biliary and pancreatic tract, gastro duodenal disease, cardiovascular disease, renal and ureteral colic.

Deep Somatic Pain

• It is generally diffused, less localizable than cutaneous pain. Somatic structures vary in their sensitivity to pain.
• Highly sensitive structures include tendons, deep fascia, ligaments, joints, bone periosteum, blood vessels and nerve.
• Skeletal muscle is sensitive only in stretching and ischemia.

Localized Pain

• It arises directly from the site of the disturbance.

Referred Pain

• It is one which is felt in a part of the body which is remote from the actual point of stimulation.
• The impulses usually arise in an organ, but the pain is projected to a surface area of the body e.g. angina pectoris, the pain originates in the heart muscles, but it may be experienced in the mid-sternal region, the base of the neck and down to the left arm.

Intractable Pain

• Persistent, severe pain that cannot be effectively controlled by the usual medication.
• It produces prolonged and intense bombardment of the central nervous system which is very difficult to bear.

Psychogenic Pain

• It is experienced when there is no detectable organic lesion.
• It refers to pain that believed primarily due to emotional factors rather than physiologic dysfunction.
• Clients experiencing psychogenic pain have a real pain experience.

Factors Influencing Pain

The perception of pain is influenced by physiologic, psychological, and cultural factors, all of which must be considered by caregivers of persons in pain.

• Situation
  • The situation associated with the pain influence the person's response to it.
  • A person's responses to pain experienced in a formal crowed situations may differ greatly from the responses were he or she alone or in a hospital.
• Socio-cultural factors
  • It influences how people learn to react to expressing pain.
  • People respond to pain in different ways.
  • In some culture, pain may be considered as a punishment for bad deeds; therefore, they tolerate pain without complaint in order to atone for sins. In other groups, pain may be anticipated as part of the ritualistic practices of passage ceremonies and therefore tolerance of pain signifies strength and endurance.
  • Culture transmits accepted standards of behaviours including how to react to and communicate pain experiences e.g. male verses female.
  • A young girl may be allowed to cry because of pain whereas boys are not allowed to cry in some culture.
• Age 
  • It is an important variable that influences pain particularly in children and older adults.
  • Young children have difficulty in understanding pain.
  • Older people may assign different meanings to that pain, it is thought by the elderly as natural manifestation of aging. Older people may have decreased sensations or perceptions of pain; may consider pain an inevitable part of aging.
• Sex
  • In most cultures boys are expected to show less expression of pain than girls.
  • As they grow older men are also expected to express less pain than women.
• Meaning of Pain
  • The meaning of a person's pain is a factor that influences his or her responses to pain e.g. pain caused by childbirth may be responded differently from pain caused by surgery.
  • A client copes differently with pain depending on its meaning.
• Anxiety
  • When anxiety is high pain is felt greater.
  • Emotionally healthy persons are usually able to tolerate moderate or even severe pain than those whose emotions are less stable.
• Fatigue
  • Fatigue decreases coping abilities and heightens the perception of pain.
  • When people are exhausted from physical activity, stress, and lack of sleep, their perception of pain is heightened. Thus, rest from physical, emotional, and social demands as well as sleep are important measures that reduce pain. 
• Attention 
  • The degree at which a client focuses on pain can influence pain perception.
  • Increased attention has been associated with increased pain, whereas distraction has been associated with a diminished pain response. 11511 потопитель
• Physiological Factors/Neurologic Function
  • The pain perception also depends upon physiological factors such as the integrity of the central nervous system, level of consciousness.
  • Any factor that interrupts or interferes with normal pain transmission affects the awareness and response of clients to pain and places them at risk for injury. Analgesics, sedatives, and alcohol depress the functioning of the central nervous system and some diseases (such as leprosy, or Hansen's disease) damage peripheral nerves, decrease sensitivity to touch and pain, and render affected individuals more vulnerable to injury.
• Previous Experience
• Each person learns from painful experiences.
• Patient had repeated experience of pain may be better prepared to tolerate or take necessary actions to relieve pain to some extent.
• Coping style
• Family and social support
• Genetic Makeup
• Recent research suggests that sensitivity to and tolerance for pain may a genetically linked trait.

Assessment of Pain

Pain assessment is one of the most common and difficult activities. The relief and management of pain require careful assessment of the caused, severity and type of pain. It needs a good rapport with the person in pain. Assessment can be subjective and objective.

Factors to Consider in a Complete Pain Assessment are:

• The intensity
• Timing
• Location
• Quality
• Personal meaning
• Aggravating and alleviating factors
• Pain behaviors

Subjective Assessment

Pain History

• Location- asks them to point mark the area.
• Duration- 1hr, days, at night or day, etc.
• Quality-burning, throbbing, etc.
• Intensity-scales 1 -10.
• Aggravating and relieving factors.
• Effects on one's quality life- sleep, eat, breath, walk, etc.
• Time of onset, duration and consistency.
• Associated symptoms e.g. nausea, vomiting, headache etc.
• Coping mechanisms.

Visual Analogue Scale (VAS)

A Visual Analogue Scale (VAS) is a measurement instrument that tries to measure a characteristic or attitude that is believed to range across a continuum of values and cannot easily be directly measured. It is often used in epidemiologic and clinical research to measure the intensity or frequency of various symptoms. For example, the amount of pain that a patient feels ranges across a continuum from none to an extreme amount of pain. From the patient's perspective this spectrum appears continuous their pain does not take discrete jumps, as a categorization of none, mild, moderate and severe would suggest. They are generally completed by patients themselves but are sometimes used to elicit opinions from health professionals. The patient marks on the line the point that they feel represents their perception of their current state. The VAS score is determined by measuring in millimeters from the left hand end of the line to the point that the patient marks.

Verbal Descriptor Scales: It consists of three to five numerically ranked choices of words e.g. none, slight, moderate and severe.

Objective Assessment

• Facial expression- frowning or wrinkling the brow.
• Change in vital sign.
• Restlessness, perspiration, splinting, rubbing the site.
• Lip biting, teeth clenching, limping.
• Dilation of the pupils.
• Vocalization e.g. crying, groaning, grunting and grasping.

Pain Management

The American Academy of Pediatrics policy statement on the assessment and management of acute pain in infants, children, and adolescents concludes with the following recommended strategies:

• Expand knowledge about pediatric pain and pediatric pain management principles and techniques. 
• Provide a calm environment for procedures in order to reduce distress-producing stimulation.
• Use appropriate pain assessment tools and techniques.
• Anticipate predictable painful experiences; intervene, and monitor accordingly.
• Use a multimodal (pharmacologic, cognitive behavioral, and physical) approach to pain management and use a multidisciplinary approach when possible.
• Involve families and tailor interventions to the individual child.
• Advocate for child-specific research in pain management and Food and Drug Administration evaluation of analgesics for children.
• Advocate for the effective use of pain medication for children to ensure compassionate and competent management of pain.

Pain can be managed through:

• Pharmacological methods
• Non pharmacological methods

Pharmacological Methods

• For acute and severe pain, there are several pharmacological agents that provide pain relief. Main drug forms are:
  • Balanced anesthesia/analgesia
  • Analgesics
  • Patient controlled analgesia
  • Local anesthetic agents
  • Opioid analgesic agents
• Most effective when a multi modal approach is used. It refers to the use of more than one form of analgesia concurrently.
• Medical treatments include three basic drug forms to treat pain (analgesics): Non-opioid drugs, opioid drugs, and drugs that are used to complement other analgesics (adjuvant drugs).
  • Non-opioid drugs include acetaminophen, aspirin, and non-steroidal anti- inflammatory drugs such as ibuprofen.
  • Opioid drugs include tramadol, morphine, hydromorphone, codeine, hydrocodone, methadone, meperidine, pentazocine.
  • Adjuvant drugs are often used for other purposes, but can also be very effective in the treatment of pain. Examples of adjuvant pain medications include muscle relaxants, antidepressant medications (such as amitriptyline or duloxetine), anti-seizure medications (such as carbamazepine, gabapentin), topicalanesthetic sprays, pain patches (Lidoderm and others), and nerve blocks with anesthetics.
• Non Opiod- NSAID, paracetamol
• Weak Opiod - codesine, tramadol
• Strong Opiod - morphine, pethidine, buprenorphine
• Adjuvants
  • Anxiolitics- Diazepam, Alprazolam
  • Antidepresants- Amitriptyline
  • Corticosteroids- Prednisolone, Dexamethasone

Non-pharmacological Methods

• Massage: It is a comfort measure often to aid relaxation and ease general aches and pain. It eases anxiety and muscle tension.
• Cold and heat therapies: Heat induces the vasodilation which increases the oxygen and nutrient delivery to effected area and heat decreases joint stiffness. Cold therapy causes vasoconstriction and local hyperesthesia, is effective in reducing inflammation and edema.
• Trans Cutaneous Nerve Stimulation (TENS): It is a battery operated device with electrodes, applied to the skin to produce a tingling, vibrating or buzzing sensation in the area of pain. It decreases the pain by stimulating the non-pain receptors of the site.
• Distraction: It directs a client's attention to something else and thus can reduce the awareness of pain and increase tolerance. It is most effective in mild or moderate pain.
• Relaxation techniques: Relaxation is mental and physical freedom from tension. This technique provides self-control.
• Hypnosis: It is an altered state of consciousness in which individual's concentration is focused and distraction is minimized.

Nurses Role in Pain Management

• Identify the goals for pain management.
• Establish therapeutic relationship.
• Nurses should observe:
  • Behavioral clues.
  • Walking patterns.
  • Daily activities changes.
  • Eating habits.
• Those examples can help determine other nursing interventions might have to develop in order to help client.
• lways show a caring attitude towards the patient.
• Establish a 24 hour pain profile:
  • Location
  • Character and intensity
  • Mild/severe
  • Duration
  • Precipitating factors
  • Identify associated manifestations, as well as alleviating or aggravating factors.
• Provide physical care.
• Teach the patient about pain and its relief.
  • Explain the quality and location of impending pain, for example, before uncomfortable procedure.
  • Help the patient learn to use slow rhythmic breathing to promote relaxation.
  • Explain the effects of analgesics and benefits of preventive approach.
  • Demonstrate splinting techniques that help reduce pain.
• Reduce anxiety and fears:
  • Give reassurance.
  • Offer distraction.
  • Spend time with patient.
• Provide comfort measures;
  • Proper positioning
  • Cool, well ventilated, quite room
  • Back rub
  • Allow for rest
• Administer pain medication.