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Created by serenacutbill
over 11 years ago
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Question | Answer |
Definition | Pain is the conscious perception of noxious stimuli |
Pain is individual and depends on ... | Age - young have lower tolerance, elderly may not express pain as plainly Health status Species variation (prey animals) Breed differences |
Advantages of pain | Limits extent of injury Encourages rest and healing Individual leanrs to avoid noxious stimuli in future |
Disadvantages of pain | Distressing, may increase recovery time Enhances stress response, increasing catabolism and delaying wound healing Anorexia Impairs respiration resulting in reluctance to cough and mucous retention - pneumonia |
Disadvantages of pain 2 | Self mutilation Sensitisation of CNS |
Recognising pain | What is normal for patient? Changes in personality or attitude Quiet docile becomes aggressive Aggressive animal becomes quiet Vocalisation, behaviour, movements Posture, physiological parameters |
Vocalisation | Excessive in dogs Spontaneous in cats thuogh less vocal Growling and hissing on manipulation of painful area |
Behavioural | Hyperventilation, Agitation, Reduced grooming Decreased or no appetite Dsiturbance to normal sleep pattern Inappropriate U+/F+ Changes in bowel movements (D+) |
Behavioural 2 | Aggression/resentment of handling Seek solitude or human reassurance Intereference of woundsite Attempts for escape with aggression Horses - excessive sweating/salivation Rabbits - grinding teeth Changes in facial expression |
Movement | Restlessness/reluctance to move Stiffness of limbs, gait change, inability to rise Reluctance to lie down Reduced activity Trembling, shaking, thrashing |
Posture | Abnormal posture, guarding/protecting painful area of straining Unresponsive sternal or sitting position with hunched back & head low (Cats) Attempting to rest in abnormal position |
Physiological Parameters | Increased heart & resp rate Raised body temp Mydriasis (dilated pupils) Blood biochem elevations - eg glucose, corticosteroid, catecholamine conc |
Analgesia is underused | Vets get away with it Pian difficult to assess Ignorance Misconceptions regarding use of analgesic drugs |
Analgesia is underused 2 | Misuse of drugs act Limited no. of licensed analgesic products Inertia/complacency Reservations about side effects Different attitudes-generation gap |
Why treat pain? | Correlation from humans Ethicla reasons, O' expectation Common anaesthetic agents have little or no analgesic effect Optimise recovery/healing times Minimise pain = minimise self-trauma |
Types of Pain | Acute pain Chronic pain |
Acute pain | Sudden onset, immediately after injury Disappears when injury healed Intensity greatest in 24-72 hours Mild-severe, short duration, quickly resolves with tx |
Chronic pain | Prolonged pain - 6 months Sudden or gradual with periods of remission or exacerbation May not be associated with injury Difficult to treat |
Types of pain Somatic pain: | Ligaments, tendons, bones Easily localised throbbing/stabbing pain |
Types of pain Visceral pain: | Smooth muscle walls (abdomen, cranium, thorax) Difficult to localise Cramping/burning |
Types of pain Referred pain: | Experienced from site distant from injury |
Types of pain Phantom pain: | Sensation or burning or tingling experienced in absent limb |
Types of pain Neuropathic pain: | Abnormal processing of nervous activity resulting from injury to higher centres of brain |
Controlling pain | Endorphins Local anaesthetic agents Opioids Non-steroidal anti-inflammatory drugs (NSAIDs) NMDA receptor agonists |
Endorphins | Endogenous opiate-like peptides produced naturally in CNS Inhibit production of neurotransmitter substance & conduction of pain impulses Raise pain threshold & produce sedation & euphoria Production stimulated by TENS/acupn |
Local anaesthetic | Block all sensory input from affected area Site of injury will determine usefulness Bupivicaine or ropivacaine drugs of choice due to duration or action (not licensed) |
Topical - EMLA cream applied prior to catheter placement Local block - multiple injs in LA around area of interest with fine bore needle Local 'splash' block - Irrigating wound with LA prior to closure | Regional block - LA admin around nerve, desensitising whole area it supplies Epidural - LA inj into epidural space between dura mater & periosteum providing desensitisation of all nerves leaving spine from there |
Opioids | Partial mu agonists - eg Buprenorphine Less reliable against wide pain type Poor dose/response relationship If ineffective increasing dose often does not increase analgesic effect Difficult to change to alternative |
Effects of opioid analgesia | Analgesia, sedation, euphoria (cats), resp depression, cough suppression, nausea, V+, constipation, mydriasis (pupillary dilation) |
Opioids | Controlled under Misuse of Drugs Act Similar modes of action, activity varies between receptors - mu, kappa, sigma, delta Full-mu agonists (morphine) most reliable pain relief |
Examples of opioids | Morphine, Pethidine, Papaveretum, Methadone, Fentanyl, Etorphine, Buprenorphine, butorphanol |
Admin of opioids | iv - not pethidine, i/m - pethidine stings s/c - variable uptake Oral - metabolism affects efficacy Sublingual - technically difficult Rectal - Suppositories Epidural - GA, sterilty, skill needed Transdermal - Fentanyl patches |
NSAIDs | Inhibit synthesis or prostaglandins, production of COX Block peripheral sensitisation Long duration of effect Antipyretic No sedation |
NSAIDs | Greater effect if given pre-emptively Carprofen, Meloxicam, Tepoxalin Compromise renal blood flow GI ulceration in long term use |
NMDA receptor agonists | N-methyl-D-aspartate agonist Ketamine, tiletamine - excellent for somatic/neurological pain, poor for visceral Shot duration of action |
NMDA receptor agonists | Increased doses produced increased analgesia but also dissociativeness Excellent analgesic as slow infusion either alone or in combo with morphine/lidocaine (IVFT) Observe for toxicity if lidoc used Synergy with opioids |
Objective assessment of pain | Simple scoring system useful for standardising pain assessment Assessment of patient behaviour, general demeanour, appetite, pain response Freq of assessment depends on presenting problem - 2h |
Objective assessment of pain | Many pain scales produced with no single accepted method. Tailoring to individual practice needs is important Patients with chronic pain should be assessed every 3m or when meds ineffective |
Scoring System | 0 = no pain, signs of discomfort, resentment to firm pressure 1 = some pain, no discomfort, resentment to firm pressure 2 = mod pain, some discomfort, made worse by firm pressure 3 = severe pain, overt signs of persistent discomfort, made worse by firm pressure |
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