Pain

 

About 50% of patients first present c/o pain - people relate pain to disorder

 

What is pain

Is a subjective reaction to an objective stimulus

A sensory experience evoked by tissue damage

 

The value of pain

Prevents tissue damage/ avoids further damage

Promotes immobilisation for healing

Informs the individual of damage

 

Forms of pain

Localised

Referred

Phantom

 

Experimental study

Threshold - when a stimulus starts to hurt

Tolerance - when the pain becomes unbearable

 

 

Levels of pain physiology

 

Receptor level

Nociceptors - free nerve endings

Depolarisation threshold - sensitisation may increase nociceptor firing

 

fast pain    - A fibres

slow pain   - C fibres

 

May be aggravated by peripheral a neuroma

Areas without nociceptors can not feel pain

 

Spinal cord level mechanisms

All sensory information enters the cord via the dorsal root into the dorsal horn

After this impulses are transmitted to the brain in the spinothalamic tract

The cord is the first level of pain modulation

 

Nociception at the level of the brain

The thalamus has neurones which `generate` pain

Stimulation of the ventroposterior nucleus causes pain

Cortical structures are presumably involved in the locating of pain

 

Psychology of pain

Anxiety

Expectation

Placebo

Cultural factors

Opportunity for heroics

Need for psychomotor activity

 

The experience of pain

Emotional state

Personal circumstances

Immediate environment

 

 

 

The specific pain theory

 

Pain is detected in specific peripheral receptors, passes to specialised tracts in the spinal cord, to specific pain areas in the thalamus and on to defined pain regions in the sensory cortex.

 

Problems

Not a one to one relationship

Diverse nature of pain

 

Classification/causes

 

Inflammation

Local release of prostaglandins and bradykinins

Hyperalgesia is produced

Localised hyperaemia

Redness, heat, pain, swelling, impaired function

 

Spasm

Colicky spasmodic pain

Unpredictable rhythm/reoccurrence

eg. bile ducts, ureter

 

Oxygen deficiency/ ischaemia

Sharp continuous pain

Tight, strangulating

Angina pectoris, infarction

Claudication

Mesenteric arterial ischaemia

 

Irritation of serous membranes

Pain originates in the serosal membranes

Worse when membrane is moved

Pleural pain therefore restricts chest movements

Peritonitis causes the patient to lie still - guarding is seen

Rebound or release pain is typical of peritoneal irritation

Meningitis made worse by stretching the meninges

 

Irritation of skin, muscles and joint capsules.

Also aggravated by stretching.

 

Neuropathic

 

Treatment

 

Receptor level

Aspirin inhibits the synthesis of prostaglandins

Denervation may occur due to damage of decay

Cocaine based preparations

Keep wounds moist

 

Spinal cord mechanisms

Gate theory

Afferent nociception effected by other afferent  stimulation and descending inhibition

Rubbing

TNS

 

Nociception in the brain

anxiolytics

opiates

naloxone

endorphines

psychological treatments

information, a Rx against pain (Hayward)

 

Other Treatments

Anticonvulsants

Tricyclic antidepressants

Antispasmodics

Muscle relaxants, (dantrolene)

Steroids

NSAID

Epidurals

Intrathecals

Acupuncture

Spinal cord stimulation (SCS)

 

Measurement of pain

Pain thermometer

 

Age

Neonatal pain

Babies and neonates - equivalent analgesia and

Pain in babies preterm

Third trimester

"the fetal human possesses an active central nervous system from at least the eighth week of development".

Pain reporting sometimes diminishes in older patients

 

Signs and symptoms of pain

Individual complains - facial expressions and general agitation, vocalisation 

Restlessness/lying still

Facial expression

BP down in neurogenic shock

Sweating

Increasing respiratory rate, shallow respirations

Increased pulse and blood pressure.

If prolonged and severe blood pressure may drop.

 

 

 

 

 

Role of the nurse in pain management

 

Treat the individual

Individual assessment

Psychological support must be given to minimise anxiety.

Believed,  ‘pain is whatever the experiencing person says it is existing whenever he says it does’.

Anticipate and prevent pain.

Psychological diversion 

Increasing the patients level of control

 

Remove the causes of pain

Take out splinters

Optimal positioning, pillows, slings etc.

Wounds-keep moist.

Stretching a cramped muscle will relieve spasm.

Immobilise fractures, use traction

Restore dislocated joints

Treat infections

Anti-inflammatory measures

Treat ischaemia, e.g. stop smoking, treat anaemia, CTG, reperfusion therapy, CABG

Remove the causes of colic

Surgical correction, e.g. appendicectomy

 

Give systemic analgesia

Analgesia given, effects monitored,

Patient controlled analgesia, (PCA).

The risk of addiction ?

 

Use local methods of analgesis

Local anaesthetics and opiates may be given via the epidural or intrathecal route.

 

Use gate theory

Ice packs and warm baths

Massage

Transcutaneous nerve stimulation

 

 

 

 

Chronic pain

 

 

Pain that serves no function

Pain which had a destructive effect on the individual

Persists for over 3 months

Source unknown or can not be treated or eliminated

Pain sensation often becomes more diffuse

Onset may be acute or insidious, sometimes very insidious

Persistent pain may or may not increase in frequency and severity

 

 

Features

 

Features of acute pain such as increased heart and respiratory rate are not present due to physiological adjustment

 

Irritability        Insomnia       Isolation         Feelings of helplessness and hopelessness

Gross disruption to normal psychosocial life      Loss of libido                        Depression

 

 

Classification of pain

 

1. Acute pain - usually from a primary injury, resolves when cause is removed

 

2. Subacute pain - similar to acute but lasts for days to weeks

 

3. Recurrent acute  pain - exacerbations of chronic

Intermittent chronic - occurs at specific times with pain free times, eg. migraine

 

4. Ongoing cancer pain - caused by progressive pathology

 

5. Intractable benign pain with (adequate coping) - constant pain but able to live a productive life

Persistent chronic pain is always present but may vary in intensity eg. chronic lower back pain

 

6. Intractable benign pain with inadequate coping - person completely disabled by constant pain

 

Leads to increasing social isolation

Increasing feelings of helplessness and hopelessness

All the patients world centres on modification of the pain experience

 

 

Causes

 

Neurological pain

Neuralgia is sharp spasm like pain along nerve pathways, eg trigeminal in the face and siatic

 

 

Causalgia is a form of neuralgic with burning pain associated with injury to peripheral nerves

 

Shingles        Phantom limb pain              Headache

 

 

Untreated pathology

 

Peptic ulceration

Tropical ulcers

Inflammatory bowel disorders

 

 

 

Untreatable pathologies

 

Arterial ulcers

Venous ulcers

Peripheral vascular disease

Peripheral neuropathy

Mesenteric ischaemia

 

 

 

Other causes

 

Cancer

Lower back pain

Osteoarthritis

Rheumatoid arthritis

Degenerative disorders of the spinal column

Ankylosing spondylitis, may effect spinal column and other joints

Fibrosis eg. after a joint injury or adhesions

Multiple sclerosis

An acute pain which becomes chronic, eg severe burns

Pyschogenic

 

 

 

Assessment

 

There may be an absence of the physical signs of pain in the chronic state due to the bodies compensatory mechanism - but the pain perception persists

 

P         Provoking factors, what makes it worse or relives

Q         Quality, deep, superficial, crushing, sharp, dull, gnawing, burning

R         Region and radiation, site and radiation

S         Severity and intensity on a scale

T          Times, onset, duration, frequency

 

 

Cancer pain

 

Causes

Bone destruction

Obstruction of lumens, (viscera or vessels)

Peripheral nerve involvement

Pressure from growing tumours causing ischaemia or distension

Inflammation

Necrosis

Infection

 

Stages

Early stage pain - often caused by investigations or treatments - is short term and resolves after a few days

 

Intermediate stage pain - may be caused by post operative contractures, nerve entrapment, cancer recurrence or metastasis

 

Late stage pain - occurs in terminal cancer when therapy no longer controls the disease. Pain is chronic and slowly increases in intensity, at times may be intractable. Severe chronic pain occurs in about 25% of patients who die from cancer

 

60% of people with cancer experience mild or no pain with cancer.

 

 

 

 

 

 

 

 

 

 

 

 

 

Pain as a stressor

 

What is pain

A subjective reaction to an objective stimulus

A sensory experience evoked by tissue damage

 

 

 

How may pain be assessed

 

 

 

 

The value of pain

 

 

 

 

Factors which influence an individuals response to pain

 

 

 

 

Acute pain

Usually from a primary injury, resolves when cause is removed

 

Acute pain generates an alarm reaction consistent with the first stage of the general adaptation syndrome

 

Signs

 

 

 

 

Symptoms

 

 

 

Chronic pain

In chronic pain the physiological effects of the alarm reaction subside, this is consistent with the second stage of resistance or adaptation of the general adaptation syndrome.

 

 

 

Pain physiology

 

Nociceptors

 

 

 

Spinal cord

 

 

 

Thalamus

 

 

 

Sensory cortex

 

 

Stress which may increase pain perception

 

 

Stress which may reduce pain perception

The value of pain

Protects us from current tissue damage

Correlated with start of tissue damage, e.g. water at 45oC

Correlated with rate of tissue damage, e.g. water at 100oC

Prevents pressure sores

Prevents joint damage

Avoiding tissue damage through memory

Promotes immobilisation to aid healing

Promotes rest to aid haemostasis

Promotes rest to promote recovery

Prompts individual to seek help

Aids in diagnosis

Generates signs and symptoms

We relate pain with disorder

 

Classification/causes

Inflammation

Spasm

Oxygen deficiency/ ischaemia

Irritation of serous membranes

Irritation of skin, muscles and joint capsules.

Neuropathic

 

Potential problems

Congenital absence of pain

Pathological neuropathy

Spinal cord injury

Psychiatric illness

Unconsciousness

Intoxication

Analgesic abuse

Local anaesthetics, e.g. eyes

 

 

Individual response to pain

Anxiety

Expectation

Placebo

Cultural factors

Emotional state

Circumstances

Immediate environment

Need for changes in body position

Need for others to know

Need to take effective action

Opportunity for heroics

 

Assessment

P          Provoking factors, what makes it worse or relives

Q          Quality, deep, superficial, crushing, sharp, dull, gnawing, burning

R          Region and radiation, site and radiation

S          Severity and intensity on a scale

T          Times, onset, duration, frequency

 

Chronic pain

Pain that serves no function

Pain which had a destructive effect on the individual

Persists for over 3 months

Source unknown or can not be treated or eliminated

Pain sensation often becomes more diffuse

Onset may be acute or insidious, sometimes very insidious

Persistent pain may or may not increase in frequency and severity

 

Features of chronic pain

Irritability

Insomnia

Isolation

Feelings of helplessness and hopelessness

Gross disruption to normal psychosocial life

Loss of libido

Depression

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The value of pain

  

Inability to feel pain

 

Components of pain

 

Sensory component

 

Affective component

 

Autonomic component

 

Motor component

 

Descriptions of pain

 

Acute and chronic pain

 

Superficial or deep pain

 

Pain threshold

 

Pain tolerance

 

Pain perception at the peripheral level

 

Nociceptors

 

Local anaesthetics

 

Aspirin

 

Basic care

 

Sharp and dull pain

 

Fast and slow pain neurons

 

Pain transmission into and up the spinal cord

 

Spinothalamic tract

 

Pain processing in the brain stem, thalamus and sensory cortex

 

Fast pain fibres

 

Slow pain fibres

 

Common causes of acute pain

 

Inflammation

 

Hypoxia and ischaemia

 

Spasm

 

Irritation of internal membranes

 

Pain from the skin

 

Neuropathic pain

 

Common causes of chronic pain

 

Untreated pathology

 

Untreatable pathologies

 

Musculoskeletal

 

Cancer pain

 

Stages of cancer pain

 

Other presentations of pain

 

Referred

 

Phantom pain

 

Clinical features of pain

 

Acute pain

 

Chronic pain

 

Assessment of pain

 

Age and pain

 

Pain inhibition physiology

 

Central descending inhibition of pain

 

Observations about descending inhibition

 

Clinical applications of descending inhibition

 

Ascending inhibition of pain (gate theory)

 

Clinical applications of ascending inhibition

 

Placebo effect

 

Treat or remove the cause of pain whenever possible