Lecture 22 11/25/24 Flashcards
What are the general characteristics of pain?
-unpleasant and aversive sensation
-complex and multifactorial
-emotional, subjective, and individual
-associated with damages/possibility of damages to body
-modifies animal behavior and expressions
What are the characteristics of transduction?
-conversion of noxious stimuli into action potential
-occurs at level of nociceptors of primary afferent A-delta and C fibers
-site of peripheral sensitization
What is transmission?
propagation of action potential through first order neurons
What is the role of A-beta fibers?
-touch, vibration, pressure, and innocuous stimuli
-involved in allodynia and central/peripheral sensitization
What is the role of A-delta fibers?
strong, rapid, sharp, localized, acute pain
What is the role of C fibers?
slow, burning, diffuse, dull pain
What are the characteristics of modulation?
-process by which nociceptive signal is augmented or inhibited after first order neuron synapse with second order neuron in the dorsal horn of spinal cord
-central sensitization
What is the role of excitatory neuropeptides?
facilitate/amplify pain signals in ascending projection neurons
What is the role of inhibitory endogenous neuropeptides?
dampen nociceptive response through descending analgesic systems
What are the characteristics of projection?
-process of transporting nociceptive information from the spinal cord to the brain stem, thalamus, and cortex
-second order neuron sends information to brain stem and thalamus
What are the characteristics of perception?
-cortical interpretation of noxious stimulus
-cerebral cortex is also central analgesia system
-liberation of enkephalins, endorphins, and serotonin helps to decrease/abolish pain
What are the characteristics of adaptive pain?
-can be nociceptive or inflammatory
-high pain threshold
-acute pain
What are the characteristics of maladaptive/pathological pain?
-can be neuropathic or functional
-low pain threshold
-chronic pain
What are the characteristics of acute pain?
-abrupt, temporary, and predictable
-nociceptive or inflammatory
-physiological/adaptive/biological purpose
-alters animal’s behavior to be protective
What causes acute pain to stop?
-external stimulus is removed
-inflammation has resolved
-healing is achieved
What are the characteristics of chronic pain?
-beyond expected duration of disease process/injury healing
-neuropathic/dysfunctional
-no biological purpose or clear end point
-resistant to conventional analgesic therapy
-affects physical and emotional well being
-can be maladaptive
What are the characteristics of neuropathic pain?
-important primary lesion in nervous system
-persistent painful stimuli
-chronic pain
-neuropathic pain and underlying condition must be treated
What are the characteristics of dysfunctional pain?
-pain beyond expected time of inflammation/healing
-radiates beyond original injury boundaries
-extremely difficult to treat; does not respond well to NSAIDs or opioids
-previous tissue damage can cause severe inflammation
-changes at molecular/cellular level amplifies pain
-central hyperalgesia and allodynia
What are the characteristics of tissue damage and peripheral sensitiziation?
-release of inflammatory mediators
-stimulate nociceptors
What are the characteristics of inflammation and peripheral sensitization?
-reduces the activation threshold of nociceptors
-primary hyperalgesia
What are the characteristics of central sensitization/wind-up pain?
-increased transmitter release pre-synaptically
-increased response to transmitter post-synaptically
-modulation/recruitment of A-beta fibers to transmit painful influx
-increased pain facilitation
-decreased pain inhibition
What is hyperalgesia?
exaggerated pain to a stimulus that usually provokes pain
What is allodynia?
-pain due to a stimulus that does not normally produce pain
-inflammation causes recruitment of A-beta nerve fibers
What are the characteristics of pain as a vital sign?
-daily assessment of level of pain in any patient should be scored on physical exam sheet
-should be considered a vital sign that is measured routinely
What are the objective measures of pain?
-quantification of pain
-physiological indicators
-biochemical markers
-nociceptive thresholds
-measurement of animal’s activity
What are the characteristics of subjective measures of pain?
-can be affected by variability from evaluator’s side, especially if method is not specific, sensitive, reliable, and repeatable
-most relevant methods use specific pain behavior such as facial expression or grimace scales
What are the characteristics of behavior assessment?
-key to pain assessment in animals
-want to assess whether animal’s behavior is normal or if it has changed
-want to observe patient from a distance first and then interact with patient
What are pain-related behaviors in small animal?
-slow to rise
-changes in using steps or jumping
-going outside litter box
-less interest in play
-decreased grooming
-irritability or hiding
-licking or chewing certain spots
-less energy/increased sleeping
What are pain-related behaviors in large animal?
-lameness/weight shifting/reluctance to move
-weight loss and decreased milk production
-vocalization/agitation/isolation
-abdominal pain and decreased rumination
-kicking/abduction of pelvic limbs
-avoidance
-rapid ear movement or flehming
-arched hunched back and growling
-position changes or rolling
-aggressive behavior
What are the characteristics of behavior changes associated with chronic pain?
-more gradual of a manifestation
-best to involve the owner; especially using questionnaires
-need good knowledge of pain signs/symptoms since animals are good at hiding signs
What are the characteristics of pain scales?
-include specific species behavior
-help integrate pain evaluation into physical exam
-used to evaluate efficacy of analgesic treatment
-allows for comparison of treatment
-multidimensional, specific, sensitive, reliable, and accessible
What are the types of unidimensional pain scale?
-visual analog scale
-numerical rating scale
-simple descriptive scale
What are the characteristics of multidimensional pain scales?
-evaluates physiologic, behavioral, and interactive parameters
-each parameter has a simple descriptive scale
-allows observer to assign numbers based on description
-total pain score helps to identify and grade pain
-helps determine need for rescue analgesia
What are the characteristics of facial expressions?
-indicators of emotion
-animals demonstrate unconscious micro-facial expressions that cannot be hidden as easily as behavior
-help to identify pain in non-verbal individuals and animals
What are the consequences of untreated pain?
-decreased appetite
-weight loss
-lack of hydration
-impaired intestinal and renal function
-delayed wound healing
-higher risk of infection and bad hygiene
-disturbed sleep
-aggressive/irritable behavior
What are the advantages of treating pain?
-earlier return to eating/less chance of weight loss
-less catabolism
-more rapid recuperation
-better healing
-better intestinal and renal function
-acceptance of treatment and manipulation
What must be factored into an analgesic protocol?
-intensity of anticipated pain
-age of patient
-concomitant disease
-breed and/or genetic predispositions
-availability of molecules/modality, including cost
What are the characteristics of preventive analgesia?
-administration of analgesic prior to occurrence of painful stimulus
-allows for a decrease in pain intensity pre, intra-, and post-operatively
What are the characteristics of multimodal analgesia?
-combination of different analgesic modalities
-improves analgesic potency of protocol
-minimizes side effects of each modality
What are the pharmacological analgesic modalities?
-local anesthetics and loco-regional analgesia
-opioids
-NSAIDs
-alpha-2 agonists
-ketamine and amantadine
-tramadol
-gabapentin
What are the non-pharmacological analgesic modalities?
-cold therapy
-acupuncture
-physiotherapy
-weight loss
What should be considered when treating surgical pain?
-if any loco-regional blocks can be done
-best opioid for each case
-any contraindications to NSAID administration
What are the steps to treating arthrosis?
-weight loss
-NSAIDs
-modification of environment
-physiotherapy
-glycosaminoglycan/proteoglycans
-diets rich in essential fatty acids
