Pain Detection & Analgesia Flashcards
What is pain?
-a sensory experience that is associated with tissue damage
What do we want to avoid pain in patients?
-stress to the patient
-prolonged recovery
-poor or delayed wound healing
-self trauma
-reduced food intake
-reduced mobility
What is acute pain?
-could follow surgery or a traumatic injury
-sometimes serves a protective function
What is chronic pain?
-“bad” pain or pathologic pain
-may be associated with sensitisation of the nervous system
What is the physiology of pain?
-painful stimulus associated with tissue damage and release of inflammatory mediators leading to activation of pain receptors in pain fibres (nociceptors) , nociceptors transmit pain signals to the CNS via pain pathways
What is nociception?
The process of feeling pain
What are the 4 processes of pain perception?
-transduction
-transmission
-modulation
-perception
What is the transduction stage?
-pain id detected by nociceptors that then convert the painful stimulus into a nervous, electrical signal
What is the transmission stage?
-the impulse is transmitted via pain fibres into the dorsal horn of the spinal cord, and eventually to the thalamus
What is the modulation stage?
-the signal is modulated in the CNS
What is the perception stage?
-information is sent to the thalamus and cerebrum of the brain where perception of pain occurs
What is nociceptive pain?
-physiological pain, protective and usually transient
What is inflammatory pain?
-due to the release of inflammatory cytokines
What is neuropathic pain?
-damage or dysfunction of the nervous system itself
What is ongoing pain?
-continuing or severe pain can cause hesitation of both peripheral and central pain pathways
-can eventually change the way the animal responds to stimulus
What is pre-emptive analgesia?
-the administration of analgesics prior to tissue trauma
-aims to prevent pain pathway sensation and to allow for easier pain management post-op
What are examples of full agonist opioids, and when might they be used?
-methadone
-butorphanol
-for moderate to severe pain, can be topped up
-increasing dose, increases analgesia
-used in spays or fracture repair
What is an example of partial agonist opioids, and when might they be used?
-buprenorphine
-mild to moderate pain
-used in superficial surgeries or stitch ups
How do NSAID analgesics work?
-inhibit the production of inflammatory mediators
-work by inhibiting enzymes and work at the transduction stage of the pain pathway
What are examples of NSAID analgesic drugs, and their uses?
-Meloxicam
-carprofen
-aspirin
-paracetamol
-peri-operative pain and management of chronic pain
How can NSAID analgesics affect the renal system?
-prostaglandins play a role in maintaining GFR and renal blood flow in the face of low BP
-so inhibition of PGs may lead to renal dysfunction or failure
How can NSAID analgesics affect the GIT?
-cox 1 enzymes are responsible for mucus secreting and maintaining blood flow to the gut
-may cause gastric ulceration
What are alpha 2 adrenoceptor agonists, and examples of analgesia drugs?
-sedative drugs with analgesic effects
-used in lower doses to achieve only analgesia
-Medetomidine
-dexmedetomidine
What is local anaesthesia and examples of drugs?
-provides total analgesia as they block the conduction of nociceptive impulses e
-lignocaine
-bupivicaine
