Analgesia Flashcards
(39 cards)
How is pain defined by the International Association for the Study of Pain (2018)?
An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage
The definition was updated from the original in 1979.
What are some clinically significant negative side effects of pain?
- Immobility
- Retarded bone healing
- Decreased pulmonary function
- Increased myocardial work
- Increased oxygen consumption
- Stress hormone release
- Inappetence
- Insomnia
- Overall catabolic state
- Lengthened wound healing time
- Patient suffering
What factors influence an individual’s response to pain?
- Age
- Sex
- Health status
- Species variation
- Breed differences
What is physiological or nociceptive pain?
An acute pain arising from stimulation of nociceptors by a noxious stimulus, generally of short duration
It varies in severity and is induced by traumatic, surgical, or disease processes.
What characterizes pathological pain?
Usually chronic and develops from intense and repeated stimuli causing persistent discomfort and abnormal sensitivity
Chronic pain lasts from months to years and may require multiple therapeutic approaches.
What protective role does pain serve?
Minimizing tissue damage and prompting animals to prevent further damage
However, unrelieved pain has no beneficial effects.
What are the four physiological processes involved in pain perception?
- Transduction of a noxious stimulus
- Transmission of the message to the spinal cord and brain
- Modulation of the message at synapses
- Integration of electrochemical events with individual psychology
What are some behaviors indicative of pain in animals?
- Changes in personality or attitude
- Abnormal vocalization
- Licking or biting a painful area
- Changes in hair-coat appearance
- Changes in posture or ambulation
- Changes in activity level
- Changes in appetite
- Changes in facial expression
- Excessive salivation
- Changes in bowel movements or urination
What signs indicate pain in dogs?
- Hunched back
- Guarding the painful area
- Abnormal posture
- Stiff movement
- Limping
- Vocalizations (screaming, whining)
- Agitated behavior
- Poor grooming
- Decreased appetite
What signs indicate pain in cats?
- Hunched back with head lowered
- Guarding the painful area
- Abnormal posture
- Vocalizations (screaming, yowling)
- Hyperventilation
- Poor grooming
- Decreased appetite
- Acts out of character
What is the purpose of pain scoring systems in veterinary practice?
To quantify pain and define a level of severity for administering ‘rescue’ analgesics
They help assess the efficacy of treatment.
What is pre-emptive analgesia?
Administering analgesic drugs before the onset of pain to allow for better pain control during the postoperative period
What are some adjuvants to pain management?
- Heated cage or warm blankets
- Comfortable bedding
- Bandaging or padding
- Splinting
- Urinary catheterization
- General nursing care
- Interaction with owners
- Nutritional support
- Complementary therapy
What are the classes of drugs with analgesic properties?
- NSAIDs
- Steroids
- Local anaesthetics (lidocaine, bupivacaine)
- Opioids (morphine, buprenorphine, fentanyl)
- alpha2-agonists (medetomidine)
- NMDA receptor antagonists (ketamine, nitrous oxide)
- Other (tramadol, gabapentin, paracetamol)
How do NSAIDs work?
They inhibit the cyclooxygenase (COX) enzyme, resulting in anti-inflammatory, antipyretic, and analgesic effects
They produce much of their analgesic effect centrally.
What are some side effects of NSAIDs?
- GI ulceration
- Nephrotoxicity
- Hepatotoxicity
- Decreased platelet function
What are local anaesthetics and their mechanism of action?
Amide local anaesthetics (e.g., lidocaine, bupivacaine) block sodium channels in neuronal membranes, inhibiting action potential generation
They may be administered epidurally or intrathecally.
What are the side effects of local anaesthetics?
- Cardiovascular toxicity
- Neurotoxicity
What are the side effects of bupivacaine?
- Cardiovascular toxicity (arrhythmias and myocardial depression)
- Neurotoxicity (muscle twitching, convulsions)
Bupivacaine is more cardiotoxic than neurotoxic, while lidocaine is the opposite.
How do opioids produce analgesia?
By acting on specific opioid receptors (mu, kappa, delta) and inhibiting pain transmission
Opioids mimic the effects of endogenous opioids produced in the body.
List the classifications of opioids based on their action on receptors.
- Agonist (morphine, fentanyl, pethidine, methadone)
- Partial agonist (buprenorphine)
- Agonist-antagonist (butorphanol)
What routes can opioids be administered?
- Intravenous
- Intramuscular
- Subcutaneous
- Epidural
- Transmucosal
- Per os
- Intrathecal
- Transdermal (fentanyl)
- Intra-articular
What are the common side effects of opioids?
- Sedation
- Bradycardia
- Excitement or dysphoria
- Respiratory depression
- Hypotension
- Nausea and vomiting
- Hypothermia
- Urine retention
- Constipation
What are the analgesic effects of low doses of medetomidine or dexmedetomidine?
Measurable analgesia with milder cardiovascular side effects
These drugs can be reversed with atipamezole.
