Chronic Pain

What factors may effect how pain is perceived?

Pain is a subjective experience to an objective stimuli, therefore varies significantly between individuals and situations. The amount of pain experienced bears little relation to the degree of tissue damage. 60% of injured soldiers reported little or no pain following severe injuries in battle. This is presumably related to the overriding need to survive. So called phantom pain occurs in a "part" of the body which has been amputated.

Anxiety is perhaps one of the main factors which exacerbates pain. Other potentially influencing factors in pain perception include expectation, cultural factors, emotional status, personal circumstances and the immediate environment.

What are the signs and symptoms of pain?

The individual may describe the sensory experience of pain if he or she is able to do so. Pain is also an unpleasant disturbing affective experience. The autonomic nervous system may be effected causing sweating and increasing parameters such as respiratory rate, pulse and blood pressure. If pain is prolonged and severe blood pressure may drop through the mechanism of neurogenic shock. There is also usually motor expressions of pain, such as thrashing about or lying still, facial expressions and general agitation, this is often accompanied by some vocalization consistent with the symptom of suffering.

How may the degree of pain be assessed?

Pain threshold is the point at which a stimuli is first described as painful. Pain tolerance is the point when a subject is forced to withdraw or to ask for the inducing stimuli to be withdrawn. Nurses may observe for signs of pain as mentioned but should wherever possible join with the patient in pain assessment. A pain "thermometer"(15) asks the patient to assess their own pain from no pain at all, a little pain, quite a lot of pain, severe pain to unbearable pain, this may be done on a scale of 0 - 5 or 0 - 10.


How do analgesics work?

Aspirin and NSAIDs block the synthesis and secretion of prostaglandins, therefore prevent nociceptor sensitization. Other non-steroidal anti-inflammatory drugs also have analgesic properties. Opioid analgesics work by fitting into opioid receptors in the brain and spinal cord. These receptors exist for the bodies own opioid molecules such as the endorphines. General anaesthetics depress the function of the consciousness centre in the brain. Nitrous oxide reduces nervous transmission by acting on the neuronal membranes. Local anaesthetics block sodium channels in peripheral nerves.


What is the role of the nurse in pain management?

Each patient must be individually assessed and believed. The well known statement of McCafery is still valid, "pain is whatever the experiencing person says it is existing whenever he says it does". Any reports of pain must therefore be believed and acted upon. In addition nurses should be able to anticipate and prevent the occurrence of pain. Full psychological support must be given to minimise anxiety. Analgesia should be given and the effects monitored, if the pain is not effectively relived an alternative preparation should be considered in consultation with the medical staff. Patients must never be forced to wait for four hours after the administration of an non-effective analgesic. The risk of addiction from correctly administered analgesia is essentially not a potential problem.

Pain may be relieved through simple nursing measures such as optimal positioning of the patient, supporting with pillows, slings etc. Wounds may be much less painful if kept moist. Stretching a cramped muscle will relieve spasm. Ice packs and warm baths may also be selectively used. Acupuncture, massage and trans cutanious nerve stimulation may be used by suitably trained practitioners. Psychological diversion may be employed to distract the patients attention from some pains.

Increasing the patients level of control over their situation can be a helpful aspect of pain management. This principle is applied in the increasing use of patient controlled analgesia, (PCA). In addition to analgesics, pharmacological management may include the use of anticonvulsants, tricyclic antidepressants, antispasmodics, muscle relaxants, steroids and non-steroidal anti inflammatory drugs. Opioids and local anaesthetics may be given via the epidural or intrathecal route.