Case 2 - Pain Management Flashcards
what are the 4 components of pain
- transduction
- transmission
- perception
- modulation
what are nociceptors
sensory receptors that are activated by noxious stimuli that damage or threaten the body integrity.
nociceptors belong to the slowing conducting afferent a delta and C fibres. they are classified according to their response to mechanical, thermal or chemical stimuli.
what is transduction
tissue damage results in the release of inflammatory mediators which bind to nociceptors conveying a thermal, mechanical or chemical insult into an electrical signal
what is transmission
occurs at the level of a second order neurones and there are various tracts that go from the spinal cord to different parts of the brain
what is perception
information has reached the brain and is being interested through the unique cognitive network
what is modulation
descending pathways have quietened down and some of those are sending their electrical impulses and now is integrating the information and modulation from the level of the brain to thespian cord happens at various levels and though different structures in the brain
what are the principles of acute pain management
- enhanced recovery
- management of expectations
- multimodal analgesia
- opioid sparing
what is the WHO ladder not appropriate for
management of acute pain
when was the WHO ladder created
1986
diagram of the WHO ladder
how do NSAIDs reduce tissue inflammation and nociception
by inhibiting prostaglandins
where do NSAIDs mainly act
peripherally
where are selective COX inhibitors more potent
at the COX2 enzyme
what are the side effects of NSAIDs
gastrointestinal irritation and risk to gastrointestinal bleeding
NSAIDs must be used with caution in what patients
older patients with impaired renal function and heart failure
diagram showing prostaglandin production
what do local anaesthetics not work with
abbesses
names of agonist/antagonist opioids
nalbuphrine and pentazocine
what do opioids do
they reduce pain signal transmission by activating pre-synaptic opioid receptors. this leads to reduced intracellular cAMP concentration, decreased calcium ion influx and thus inhibits the release of excitatory neurotransmitters
what are 2 examples of excitatory neurotransmitters
glutamate and substance P
what do opioids do at the post synaptic level
opioid-receptor binding evokes a hyperpolarisation of the neuronal membrane which decreases the probability of the generation of an action potential
what do opioids also function as
inhibitory transmitters of the descending inhibitory pathway
what other supraspiinal structures do they affect
the thalamus, and the limbic system altering the emotional assessment of pain i.e nociceptive sensations are still perceived but is no longer felt as being unpleasant or threatening
what does morphine do
by an action on mu receptors, inhibits the release of several different neurotransmitters including acetylcholine, glutamate and substance P
what type of pain serves no adaptive purpose
chronic pain
what is peripheral sensitisation
is a reduced threshold and an increase in responsiveness of the peripheral ends of nocicpetors
what does central sensitisation imply
changes in the spinal cord and brain. central sensitisation is an increase in the excitability of neurones within the central nervous system, so that normal inputs begin to produce abnormal responses. hyperalgesia for example is a phenomenon which is a result of central sensitisation
what is central sensitisation from
from a low threshold mechanoreceptor and that jumping on results In a low threshold input lie rubbing or touching and being perceived as pain
what is hyperalgesia caused by
the increase release of glutamate to a given stimulate which increases signalling to the brain
what can influence physiological changes
biological factors
what are psychological factors reflected in
the appraisal and perception of internal physiological phenomena
what are these appraisals and behavioural responses influenced by
social or environmental factors
what does the model also propose
that psychological and social factors can influence biological factors, such as hormone production, activity in the autonomic nervous system and physical reconditioning
what is neuropathic pain
pain arising as a direct consequence of a lesion or disease affecting the somatosensory system
why does neuropathic pain need to be distinguished from pain
die to secondary neuroplastic changes in the nociceptive system resulting from sufficiently strong nociceptive stimulation
what is malingering
is defined as the conscious fabrication of symptoms to achieve some form of benefits such as attention, to be relieved of undesirable activities, to obtain prescription medication or to qualify for disability compensation
what are pain behaviours
non-conscious modes of communicating pain and distress and unlike cases of symptom magnification and malingering are not produced intentionally
what does catastrophising consist of
extremely negative thoughts about ones plight even with minor problems being interpreted as major catastrophes.
catastrophising and consequently adaptive coping strategies are important in determining ones reaction to pain. greater catastrophising and feeling a lower sense of control are among the most important predictors of chronic back pain
what is the red circle
a psychologically based rehabilitation program delivered in a group setting by an interdisciplinary team,
who are the core members of this red circle team
clinical psychologist, a physiotherapist and a medical practitioner
what are the aims of the red circle
help patients move from a medical model of pain to a biopsychosocial model of pain and disability
Build patients self management skills and reduce reliance on healthcare professionals
Educate about the physiological effects of pain
Address psychological, social and emotional barriers to progress
what is an interventional destructive pain procedure
radiofrequency - denervation of the facet joints
what are the non-destructive interventional pain procedures
- local anaesthetics
- steroids
- epidural and facet joint injections
- neuromodulation: SCS and intrathecal opioids
what is the traditional tonic stimulation
- relatively low energy
- recharge every 2 months
what is burst stimulation
- parameters within traditional range
- low-moderate energy
- average recharge similar to tonic
- device provides both tonic and burst
- same expected device life as tonic
what is high frequency
- parameters outside traditional range
- highest energy, daily recharge
- current device only provides high frequency stimulation
- reduced device life compared to tonic
what is neuromodualtion
the alteration of nerve activity though targeted delivery of a stimulus, such as electrical stimulation or chemical agents, to specific neurological sites in the body
what is TENS
transcutaneous electrical nerve stimulation
what does TENS do
introduction of pulses of low-voltage electricity into tissues for the relief of pain.
- it works by means of a small portable battery operated unit with leads connected to electrodes attached to the skin; the strength and frequency of the pulses, which prevent the passage of Pain impulses to the brain, can be adjusted by the patient
the electrodes are often placed on the area of pain or at a pressure point, creating a circuit of electrical impulses that travel along nerve fibres
what are TENS electrodes used to activate
large diameter afferent fibres that overlap the site of injury and pain.
- stimulation of the dorsal columns via surface electrodes presumably receives pain because it activates large numbers of A beta fibres synchronously.
how are TENS machines thought to work
- high pulse rate triggers the pain gate to close
- a low pulse rate stimulates the body to make its own endorphins
what do pain management programmes work in synergy with
CBT to teach how to live successfully with pain
