PAIN MANAGEMENT

Chapter 35 PAIN MANAGEMENT



OBJECTIVES



• Define the key terms/concepts

• Describe the physiological processes whereby pain sensations are received, transmitted and interpreted

• State the factors influencing an individual’s perception of, and reaction to, pain

• Describe pain assessment methods, including the differences required in approach with an individual suffering chronic pain

• Describe various methods of pain management, including both non-pharmacological and pharmacological approaches

• Apply appropriate principles in planning and implementing nursing actions to prevent and to alleviate an individual’s pain


KEY TERMS/CONCEPTS


acute pain

analgesic

chronic pain

endorphins

epidural infusion

gate-control theory

pain

pain tolerance

patient-controlled analgesia (PCA)

threshold

transcutaneous electrical nerve stimulation (TENS)



CHAPTER FOCUS


Pain is both an unpleasant physical sensation and a social and emotional experience. Each episode of pain is a unique personal event. It is a universal human experience occurring across the life span, but, because no one can fully appreciate the pain of another person, pain is always a subjective experience.


Pain may be mild or severe, acute or chronic. Pain is difficult to define, as it is an individual experience with varying levels of intensity, and it may be physical, psychological or emotional in origin. Pain is often described as being a sensation of distress or suffering caused by a particular stimulus. A definition of pain that has been widely accepted and used by many nurses is that of McCaffery, a highly recognised pain care specialist (McCaffery & Pasero 1999). Her definition encompasses the idea that ‘pain is what the person says it is, and exists when he [sic] says it does’. Pain is increasingly being considered a condition rather than a symptom, and ideas about pain and its management are constantly changing.


Assessment and management of an individual’s pain may pose a significant challenge for the health care team. Supportive nursing care for a person in pain can play a huge part in this challenge.




LIVED EXPERIENCE




I’d like to, just once, wake up in the morning and know that today there would be no discomfort or pain. I spend a few hours each morning just trying to get ‘ready’ for the day — I use warm water, heat packs, medication, magnets … anything to try and help achieve some comfort. The end of the day often isn’t much better than the start, but hopefully for a couple of hours in the middle of the day, I’m reasonably functional. I try other alternative treatments too; acupuncture seems to help a little, but some days, it all seems too hard, and the whole of my being is affected by my pain.


Rebecca, 41, with chronic pain syndrome



PHYSIOLOGY OF PAIN


Pain is one of the most common causes of discomfort, and pain avoidance is viewed by Maslow (in Crisp & Taylor 2005) as a first priority physiological need. Pain avoidance appears to be an instinctive reaction to harmful factors in the environment; for example, a newborn will draw away from a painful stimulus. Throughout the life cycle, people will avoid painful stimuli or take actions to withdraw from such stimuli. The ability to relieve or to control pain depends on an understanding of how it occurs and how it is controlled by the brain. The physical experience of pain can be divided into four distinct phases: the stimulus which causes the pain, the transfer of pain, the perception of pain and the reaction to pain.


When pain receptors are stimulated they send electrical impulses along special pathways to the spinal cord. These pathways may be seen as being similar to a two-lane road, one lane with large diameter fibres for fast message transmission (‘A’ fibres), and one lane with smaller diameter fibres for slower message transmission (‘C’ fibres). ‘A’ fibres have the most insulation, and carry information that reflects throbbing and pricking types of pain. Slow pathways (‘C’ fibres) have less insulation, and carry impulses that represent burning pain. Pain receptors in the skin and other tissues are free nerve endings, some of which are the peripheral terminations of small diameter ‘C’ fibres, while others are the slightly larger diameter ‘A’ fibres. When histamine and other naturally occurring chemical substances are released as a result of tissue damage, pain sensations travel along the nerve fibres. Regardless of the type of pain, and whether travelling slowly or quickly, pain impulses are transmitted to the dorsal root ganglia of the spinal cord, where they synapse with certain neurons in the posterior horns of the grey matter. Pain sensations are then transmitted to various areas of the brain by synapses at the thalamus, where they are perceived and interpreted (Figure 35.1).


image

Figure 35.1 The pathway of pain


Pain causes both reflex motor reactions and psychic reactions. Some of the reflex actions occur directly from the spinal cord, where small neurons in the grey matter transmit an impulse straight from the skin to the muscles, without brain involvement. For example, a painful stimulus to the hand, such as extreme heat, initiates reflex contraction of the flexor muscles that cause withdrawal of the arm from the heat source.


Although the complex mechanisms of the physiology and psychology of pain are not understood completely, there are several theories of pain. The gate-control theory of pain (Melzack & Wall 1965) suggests that neural mechanisms in the dorsal horns of the spinal cord can act like a gate. This theory suggests that activity in the large diameter nerve fibres can close the gate and block pain impulses, resulting in a decrease or elimination of pain sensation. Therefore, according to this theory, it is possible to block pain impulses travelling to the brain by stimulating the large ‘A’ nerve fibres and ‘closing the gate’. This theory may help to explain the reason why cutaneous stimulation (rubbing a sore spot) or acupuncture can relieve pain, as in acupuncture, stimulation of non-painful nerve fibres can ‘confuse’ messages and suppress pain signals.


It is acknowledged that pain can be inhibited along the course of transmission and that endorphins play a complex role in closing the gate to pain. Endorphins are naturally occurring substances with opioid qualities, which combine with the same receptors as morphine and other narcotics, producing the same effect (i.e. analgesia). They act as neurotransmitters that mediate the transmission of pain information. As a result of pain or stress, an impulse from the brain may trigger the release of endorphins from pain-inhibiting neurons in the dorsal horn, which block transmission of the pain impulse before it reaches the brain. Various studies have shown that plasma endorphin levels increase in states of stress, and also that acupuncture and transcutaneous electrical nerve stimulation (TENS [discussed later in this chapter]) increase endorphin release. Therefore, although incompletely understood, it is known that the body has some internal mechanisms that help to control pain and its perception.



CAUSES OF PAIN


Pain is often a useful protective signal, as it can be a warning of actual or impending tissue damage. The sensation of pain can also warn the individual of emotional or stress-related problems, such as a headache caused by tension or anxiety. Pain can result from many sources or stimuli, including mechanical trauma, chemical irritants, extremes of temperature, ischaemia and psychological factors.



Ischaemia


Ischaemia (decreased blood supply to an area or body part) causes cell damage or destruction with the subsequent release of irritating chemical substances that stimulate the pain nerve endings.



Chemical irritation


Stimulation of sensory nerve endings by irritant chemicals from an external source, such as acid, or by chemical substances released by damaged cells (histamine) will cause pain. Substances may leak from an organ into the peritoneal cavity and stimulate large areas of pain fibres causing severe pain; for example, gastric juice may escape as a result of a perforated gastric ulcer.



Mechanical trauma


Pain may result when body tissues are stretched; for example, distension of a hollow organ such as the stomach or bladder. When tissues are contracted, as in muscle spasm, pain occurs as a result of local ischaemia, stretched nerve endings and from an accumulation of metabolic wastes. Prolonged pressure on tissues causes local ischaemia and pressure on nerve endings and, consequently, pain. Physical force, such as a hard blow to the tissues results in initial pressure on the nerve endings and subsequent irritation from substances released by the damaged cells.



Extremes of temperature


Extremes of heat or cold (thermal trauma) may damage tissues and cause pain. Burns or scalds damage nerve endings, and frostbite causes local blood vessel constriction and ischaemia.



Psychological factors


Pain may be experienced in the absence of any physiological cause, or as a result of the physical manifestations of psychological disorders, such as abdominal cramp or headache resulting from stress or anxiety. Emotional distress causes increased muscle tension that can lead to aches and pains in a variety of areas, such as neck or back pain.



TYPES OF PAIN


Acute pain is usually of rapid onset and varies in intensity and length of time it lasts. It is often perceived as an incident of high severity. In most cases it is self-limiting, and has a predictable management and end. It is often able to be precisely located and described. Acute pain, if mild, may require no specific intervention, and more severe acute pain can usually be managed successfully. Acute pain may result from injury, infection, or after surgical intervention. When tissue damage is the cause, pain declines as the tissues heal.


Chronic pain is considered to be pain that has lasted for at least 6 months and is an ongoing experience that fails to resolve naturally or does not respond well to intervention. It is often no longer considered to be pain that warns of impending danger or tissue damage. Chronic pain is constant or intermittent and the individual often has difficulty localising it. The pain from arthritis may be regarded as chronic pain. An individual who experiences unrelieved pain for an extended period often feels trapped and helpless. The client’s anxiety increases and they become preoccupied with their pain and state of health. Sleep disturbances and fatigue may be experienced and irritability, aggression, or withdrawal and depression may result.


Superficial (cutaneous) pain originates in the skin or mucous membranes, as a result of stimulation of nerve receptors in those areas. Because there are large numbers of sensory nerve endings on the surface of the body, a person is usually able to localise and describe surface pain accurately.


Deep (visceral) pain originates in internal body structures as a result of stimulation of receptors in those areas. As there are fewer sensory nerve endings in the viscera than in skin or mucous membranes, it is more difficult to localise and describe visceral pain. Localised damage to the viscera rarely causes severe pain, whereas widespread damage causing diffuse stimulation of the nerve ending produces extreme pain. For example, occlusion of the blood supply to a large section of the intestine stimulates many diffuse fibres and can result in severe pain.


Visceral pain may be felt at a site far removed from the affected area, through the mechanism known as referred pain. Referred pain is felt in a part of the body away from the pain’s point of origin; for example, pain in the left shoulder and arm associated with myocardial infarction. In this instance, sensory neurons that transmit signals from the skin enter the same area of the spinal cord as do nerve fibres from the myocardium. The neurons carry pain signals from both areas to the brain and, because cutaneous pain is more common than visceral pain, the brain interprets the pain as originating in the skin. Figure 35.2 illustrates the common sites of referred pain in a female, but it can be noted that the sites are the same in both females and males.


image

Figure 35.2 Referred pain sites: cutaneous areas to which pain from certain viscera are referred


Phantom pain is a sensation of pain felt in a body part that has been removed, such as when the lower leg has been amputated. Although the nerves supplying the amputated part have been severed, the remaining neurons may continue to send impulses as before, and the brain still interprets the impulses as if that part were still there.


Intractable pain refers to pain that is severe and constant or unrelenting, and which is unrelieved by usual pain management measures. For example, the extreme and constant pain often associated with cancer may not be relieved by strong analgesics alone, and the individual may also require non-drug therapy such as surgery to block the nerve fibres conducting the pain impulses.


Total pain, the experience of a person with an ongoing pain syndrome, is derived from several sources. The term ‘total pain’ has been devised to address the complexity of pain as both a somatic and a psychological experience. It has been well documented that a person’s pain threshold can be lowered by psychological factors such as fear, depression and isolation, with the result that the pain experience is increased.



PERCEPTION OF PAIN


The perception of pain is individual and is therefore different for each person. In addition, a person may perceive pain differently at different times. Clinical Interest Box 35.1 provides some common biases and misconceptions about pain. The pain threshold is the point at which a stimulus, such as pressure, activates pain receptors and produces a sensation of pain. Four identifiable levels of pain threshold have been described:


1. Sensation threshold: the lowest stimulus level at which an individual perceives sensation (e.g. tingling)

2. Pain perception threshold: the lowest stimulus level at which the individual states that the continuing stimulation is painful

3. Pain tolerance: the lowest level at which the individual withdraws from the stimulation or asks to have it stopped

4. Encouraged pain tolerance: this is the same as pain tolerance, but the individual is encouraged to tolerate higher levels of stimulation.


CLINICAL INTEREST BOX 35.1 Common biases and misconceptions about pain


The following statements are false:


• Substance abusers and alcoholics overreact to discomforts

• Clients with minor illnesses have less pain than those with severe physical alteration

• Administering analgesics regularly will lead to drug addiction

• The amount of tissue damage in an injury can accurately indicate pain intensity

• Health care personnel are the best authorities on the nature of a client’s pain

• Psychogenic pain is not real

• Chronic pain is psychological

• Clients should expect to have pain in a hospital

• Clients who cannot speak do not feel pain.

(Potter & Perry 2008)


Because the perception of pain is individual, some will experience pain much earlier than others. Studies have shown that all individuals have a similar sensation threshold but that the ways in which they react to pain vary greatly.



FACTORS INFLUENCING PAIN


The ways in which different people react to pain may vary tremendously and many factors may be involved. Behavioural manifestations of pain vary according to both the individual and to factors in the environment.



Age


As infants and young children lack the ability to express themselves verbally, their pain, or the degree of pain they experience, may not be recognised or appreciated. Many misconceptions exist in relation to pain in infants, including that infants do not feel pain or are incapable of expressing pain. In addition to the physiological changes, behavioural cues, such as facial activity (including brow bulge, eye squeeze and open lips), crying behaviour and gross motor activity may indicate pain in the infant. Additionally, many children are taught from an early age that they are expected to be brave and that ‘only babies cry’. As a result, a child who is experiencing pain may endeavour to hide it. Conversely, a child may invent or exaggerate pain as a method of gaining attention.


When older children or adolescents experience pain they may think of it in terms of how it will affect their activities and the attainment of goals. As a result of misunderstanding about their body and illness, young clients sometimes harbour distressing fantasies about the significance of pain. Consequently, both anxiety and pain are increased.


The ability to tolerate pain generally seems to increase with age, and this may be partly due to expectations about what constitutes ‘adult’ behaviour. Many myths also exist, however, in relation to pain experienced by older adults, particularly those with cognitive impairment. This has resulted in an underestimation and management of pain in people with disorders such as Alzheimer’s disease. Clinical Interest Box 35.2 provides more information about pain management in clients with Alzheimer’s disease. Common misconceptions include that pain is a natural consequence of growing old, that pain perception decreases with age, and that, if the older adult does not report pain, they do not have pain.



CLINICAL INTEREST BOX 35.2 Pain management in clients with Alzheimer’s disease


(Potter & Perry 2008)


No evidence exists that cognitively impaired older adults experience less pain or that their reports of pain are less valid than those people with intact cognitive function. It is probable that clients with dementia and progressive deficits of cognition, particularly those in long-term care facilities, suffer significant unrelieved pain and discomfort. Assessing pain in these clients is challenging but possible. The best approach is to accept the client’s report of pain and treat the pain as it would be treated in a person with intact cognitive function.



Gender


Many males have been conditioned by society to be strong and brave. Some people consider that any display of emotion by a male, such as crying, is a sign of weakness. As a result of society’s expectations of acceptable behaviour, a male may internalise or suppress expressions of pain.



Culture


Cultural values, attitudes and feelings contribute to the way people react to pain. Some people have a matter-of-fact attitude to pain, with little outward expression of their suffering, while others are more expressive and seek immediate pain relief. Most Western cultures place strong values on the ability to bear pain with silent fortitude, so that external behaviours may not reveal the intensity of pain. People from Latin cultures are permitted to display their suffering openly, such as by crying or moaning, as a socially accepted response to pain. It must also be appreciated, however, that there are enormous differences within every culture and that not every person from a specific culture will react in the same manner. Clinical Interest Box 35.3 provides an example of a cultural experience of pain.



CLINICAL INTEREST BOX 35.3 A cultural experience of pain


Certain religious groups, for example, Muslims, may believe that it is God’s will for them to experience pain. Some clients may be unwilling to accept medication in case it clouds or impairs their senses. Buddhists, for example, may prefer to use meditation techniques to help relieve their pain.


(Heath 1995)

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Feb 12, 2017 | Posted by in NURSING | Comments Off on PAIN MANAGEMENT

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