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acute pain (TREATMENT OF ACUTE (paracetamol (analgesic and antipyretic
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acute pain
TREATMENT OF ACUTE
local anaesthetics
- lignocaine
- bupivacaine, levobupivacaine, ropivacaine
- analgesic effect by blockade of sodium channels in fibers nerves, stoping excitation and conduction
paracetamol
- analgesic and antipyretic
- inhibition of central cyclo-oxygenases
- activation of the endocannabinoid system
- activetion spinal serotonergic pathways
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- adverse effects
Hepatotoxicity
NSAIDS
- ANALGESIC, ANTI-INFLAMMATORY , ANTIPYRETIC
- INHIBITION OF PROSTAGLANDIN SYNTHESIS
- CONSTITUTIVE COX 1, INDUCIBLE COX 2
- ADVERSE EFFECTS:
kidney disorder
platelet disfunction- bleeding,
increase blood loss peptic
ulceration
bronchospasm
opioids
- weak opioids: codein, tramadola
- strong opioids:morfin, petidyn,fentanyl, okxykodon,
- tramadol:
- combined two effects as on opioid agonist and a serotonin and noradrenalin reuptake inhibiotor
- for weak and moderate acute pain
- morphine
strong opioid
side-effect: respiratory depression, sedation, pruritus, nausea, vomiting, urinary retention, constipation
Neuroanatomy of pain
- afferent pathways - ascending patways- transmission pain up
• From nociceptors → transmitted by small A-delta fibers and C- fibers to the spinal cord in the dorsal horn
•From spinal cord → transmitted to higher parts of the spinal cord and to the rest of the CNS by spinothalamic tracts
- Nociceptors : Endings of small unmyelinated C and lightly myelinated A delta afferent neurons
- Location: In muscles, tendons, epidermis, subcutanous tissue, visceral organs
- stimulators: chemical, mechanical and thermal noxious
- Mild stimulation → positive, pleasurable sensation
- Strong stimulation → pain
- 1st afferent neurons:
The small unmyelinated C- fibers conduct impulses slowly, which are responsible for the transmission of diffuse burning or aching sensations - visceral pain
The larger myelinated A-delta fibers occurs much more quickly, well - localized , sharp pain sensations
- 2nd afferent neurons: the parts of CNS involved in the interpretation of the pain signals the limbic system , reticular formation, thalamus, hypothalamus, cortex.
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- efferent pathways- descending patways- modulation pain
- descending pathways contribute to the modulation of pain transmission in the CNS
Types of pain
- Acute pain is a protective mechanism that alerts the individual to experience that is immediately harmful to the body. Time is up to 3 months.
- Chronic pain extends beyond the period of healing and disrupts both sleep and normal activities of living over 3 months.
INJURY RESPONSE
- Postoperative pain
- Surgical trauma
- Psychological, environmental and social factors
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transduction
When a stimulus , such as pressure is converted into a nerve signal.
These cells are known as nociceptors.
transmission
It is the process of transferring pain information to the CNS. Signals are transmitted along the axons of nociceptors.
These small-diameter nerve fibres comprise 2 main types: C and A-delta.
Most primary sensory nerve fibres , synapse with second –order neurons in the dorsal horn of the spinal cord.
Projection neurons carry information to the brainstem, thalamus, hypothalamus.
Modulation
- Many of pain signals never reach consciousness because they are stopped by modulatory activity within the central nervous system.
- Neurotransmitters involved in these descending pathways include endogenous opiates (enkephalins, dynorphins, beta-endorphins),
Perception
- Perception of pain is the awareness ,typically an uncomfortable , associated with a specific area of the body.
- Perception of pain experience is influenced by social and environmental cues, cultural conditioning,past personal experiences.
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- Hypersensitivity – increased sensitivity in the pain processing
- Hyperalgesia - increased pain sensitivity to noxious stimulation
- Allodynia -painful sensations provoked by nonstimulation, (e.g.touch)