(ĐTĐ) - Pain is a very complicated phenomenon and there are many ways of describing and classifying pain.

 

Most of these are relevant as they provide information about the different clinical aspects of pain

Definition

Pain is defined by the International Association for the Study of Pain (IASP) as: "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage". The reason for the rather complicated definition is the need to include patients with chronich pain were the actual physical cause of the pain is unknown.

The definition emphasise that there is both a sensory and an emotional aspect of pain, this is an important concept that has to be keept in mind both in the diagnosis and in the treatment of pain in seriously ill and dying patients.    

Malignant - non malignant pain

The division of pain into malignant and non-malignant pain is based on whether or not the pain is caused by cancer.

Historically this division had a practical purpose, as the use opioids was recommended only in patients with cancer.  This division is no longer valid, as it is recognised that patients with other incurable diseases may also need treatment of the pain with opioids.

In practical terms there is still an important differentiation between:

  • patients with chronic pain without an incurable disease - these patients often have long and complicated pain histories and they are seen by specialists in pain clinics
  • patients with pain due to an incurable or potientially incurable  disease  - the majority have relative simple pain history that can be treated by all doctors with the necessary knowledge.  The few patients with complicated pain should be seen by specialists in palliative medicine.   

Based on temporal onset

Acute pain is defined as: 

"A well defined temporal pain inset, generally associated with subjective and objective signs and with hyperactivity of the autonomic system."

Acute pain occur suddently usually in association with a known trauma and the patient will show the signs of acute pain: sweating, pallor, perhaps nausea and he will often be unable to relax or sleep.    

This is the pain seen in patient with acute conditions that may require acute surgical interventions.

Subacute pain:

Develop over several days, often increasing in intesity with a pattern of progessive pain symptomatology.

This is typical for pain cause by cancer; initially it is just an achebut gradually it increases in intesity and the pain becomes a warning signal to the person.

Episodic pain:

Occurs over shorter periods of time at regular or irregular intervals.

Arthritic pain that comes and goes is an example of episodic pain.

Chronic pain :

Is a pain that has persisted for more than 3 months, it often has a less defined temporal onset. There is an adaptation of the autonomic system and there may not be any objective signs. It is characterised by significant changes in the person's personality, lifestyle and functional ability.

Chronic pain is seen both in patient with and without an incurable disease. It has a profound impact on the person's life (see total pain) on the other hand the symptoms caused by the autonomic system are less apparant.

Phatophysiologically a modulation of the whole nerveous system has taken place, making the generation of pain even more complicated and difficult to treat (see pain theory). This underscores the importance of treating acute and subacute pain before it becomes a more complex chronic pain state.

Patients with continuous pain may also experience changes over time:

Baseline pain:

Is the pain reported as an average pain intesity experienced for the 12 hours or more in a 24 hour periode.

Breakthrough pain:

is a pain more severe than the the baseline pain, there are 3 different types:

Movement related episodic pain also called incidence pain 

For example when a patient who is pain free when seated develop severe pain in his leg when walking.

Non-movement related episodic pain:

For example the patient sitting in a chair who suddently experiences a severe pain shooting down his leg.

End of dose pain:

Pain occuring before the next dose of analgesics is due (see the treatment of pain)

See also

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