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
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.
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 (
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
Individual
assessment
Believed, "pain is
whatever the experiencing person says it is existing whenever he says it
does"
Anticipate
and prevent pain.
Psychological
support must be given to minimise anxiety.
Analgesia
given, effects monitored,
The risk of
addiction ?
Optimal positioning, pillows, slings etc.
Wounds - keep moist.
Stretching
a cramped muscle will relieve spasm.
Ice packs
and warm baths
Massage
Trans cutanious
nerve stimulation
Psychological
diversion
Increasing
the patients level of control
Patient
controlled analgesia, (PCA).
Local
anaesthetics and opiates may be given via the epidural or intrathecal
route.
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