- To accurately define pain
- To discuss the different types of pain and its manifestations
Definition of Pain
Pain is often a major symptom in many medical conditions and is one of the most sited reasons for seeking medical assistance . Acute pain has a protective function, it motivates us to withdraw from damaging or potentially damaging situations, protects the injured body part while it heals, and avoids those situations in the future .
An internationally recognised definition is by the International Association for the Study of Pain “Pain isan unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage” . An alternative definition is offered by McCaffrey and Beebe, “Pain is whatever the experiencing person says it is, existing whenever the experiencing person say it does” . Both of these definitions therefore highlight that a painful experience is more than just tissue damage triggering a response from the nervous system. The management of pain thus involves more than simply treating the tissue injury.
However a major difference between the two definitions is that the IASP recognises that the inability to communicate verbally does not negate the possibility that an individual is experiencing pain and is in need of appropriate pain-relieving treatment. Thus the McCaffery & Beebe  definition is not useful for the cognitively impaired or immature who are unable to report and express pain. Pain is always subjective.
Individuals learn pain through experiences related to painful instances in childhood, subsequently pain is that experience we associate with actual or potential tissue damage. It is thus undoubtedly a sensation within our body that is always unpleasant and therefore also an emotional experience .
So having defined pain, it is important to have a clear understanding of how acute pain differs from chronic pain. Acute pain is short-lasting, is a symptom, has an identifiable pathology with a response to tissue damage, has a biological function, is usually relieved by treatment and can be associated with anxiety. Pain in the perioperative period, from trauma or due to a sickle cell crisis falls into the acute pain category because it is a response to tissue damage. It is usually short-lasting, is a symptom that has an identifiable pathology and biological function and can usually be relieved by treatment.
By contrast chronic pain is long-lasting, the pathology is often unidentifiable and is a response to unknown peripheral or central changes in the somato-sensory cortex, has no biological function and can sometimes be unresponsive to treatment and can also be associated with depression and feelings of hopelessness. Patients with acute pain usually experience resolution, whereas patients with chronic pain are unlikely to do so.
Although acute or nociceptive pain is distinct from chronic pain, the boundaries are not always well defined. There is evidence that those with acute pain can suffer more than one mechanism of pain at a given time i.e. ischaemic, visceral, somatic, neuropathic or procedural pain. Furthermore, even though acute pain has a foreseeable end its management should be a high priority because acute pain may, when neglected, become chronic and persistent. Features in the acute pain history that may suggest a neuropathic element include (; ):
- clinical circumstances associated with a high risk of nerve injury eg thoracic or chest wall procedures, amputations or hernia repairs;
- pain descriptors as highlighted in the table below;
- the paroxysmal or spontaneous nature of the pain, which may have no clear precipitating factors;
- the presence of spontaneous or evoked unpleasant abnormal sensations (dysaesthesias),
- increased response to anormally painful stimulus (hyperalgesia),
- pain due to a stimulus that does not normally evoke pain (allodynia)
- areas of numbness (hypoaesthesia);
- changes in colour, temperature and sweating in the affected area and phantom phenomena.
Thus when planning effective pain management it is important to establish the pain mechanism involved, in addition to making consideration for the idiosynchrasies and needs of the specific patient group, the type of injury, the length of time the patient is likely to be nil by mouth and available resources e.g. PCA and epidural infusion device.
|Somatic Pain||Visceral Pain||Neuropathic Pain|
|Location||localised||generalised||radiating or specific|
|Patient description||Pin prick, stabbing or sharp||Ache, pressure or sharp||Burning, pricking, tingling, electric shock or lancinating|
|Mechanism of Pain||A delta fibre activity located in the periphery||C fibre activity involving deeper innervation||Dermatomal (peripheral) or non dermatomal (central)|
|Clinical Examples|| Superficial laceration,
|Periosteum, joints, muscle injury,
Colic and muscle spasm,
Sickle cell crisis, Appendicitis, Kidney stone
Post traumatic neuralgia,
HIV, Limb amputation, Herpetic Neuralgia
|Most responsive treatments||Cold packs , Tactile stimulation, Paracetamol, non steroidal anti-inflammatory drugs (NSAIDs), Opioids, Local Anaesthetic||NSAIDs , Opioid via any route, Intraspinal local anaesthetic, antispasmodic drugs, paracetamol||Anticonvulsants, Tricyclic antidepressants, Neural blockade|
The Assistive Tool for Determining Types of Pain. (Taken from Institute for Clinical Systems Improvement: Assessment and Management of Acute Pain 2008).
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- Taxonomy., I.Associatio, Bogduk, N., Merskey, H., 1994. Classification of chronic pain : descriptions of chronic pain syndromes and definitions of pain terms, 2ndnd ed. IASP Press, Seattle.
- McCaffery, M., Beebe, A., 1989. Pain : clinical manual for nursing practice. C.V. Mosby, St. Louis.
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