Pain Measurement & Assessment Flashcards
What must you be able to do before you can treat pain?
you must be able to recognize it
What are physiologic indicators of pain?
- related to activation of the sympathetic nervous system
- increased HR, BP, temperature, pupil dilation
- increased biomarkers (B-endorphin, catecholamines, cortisol, chromagranin A)
- unreliable & not specific to pain
- influenced by other factors ex: anxiety, stress, fear, & drugs
- not always present in painful animals
What are the indicators of pain?
- behaviour
- posture
- facial expression
What is the practical subjective approach to observing pain?
- observing the patient w/o interaction (patient’s orientation in cage, posture, activity level, facial expression, attitude)
- observing the patient while interacting
- observing the patient’s response to palpation of painful site
What counts as interaction with a patient when assessing for pain?
- establish contact first (call by name)
- stroke along back from head to tail
- do they respond appropriately?
- are they painful if? (uninterested, indifferent, unresponsive; tense upon interaction; anxious, aggressive, trying to get away)
How might an animal respond to palpation of a painful area?
- no reaction to touching but vocalizes/tenses up w/ pressure
- looking at the area in question
- withdrawal
- defensive by protecting the area
- withdraws fast, vocalizes, bites
- freezing, gets rigid
How painful is this cat?
moderate pain
What are some basic challenges in pain assessment?
- pain is a dynamic, complex, multi-dimensional experience involving sensory and affective components
- uniquely personal experience
What are the challenges of pain assessment in animals in particular?
- use of proxy (DVM or owner; observer is assessing somebody’s subjective experience; respondent bias)
- variation in pain response (age, species (breed), individual)
- environmental or situational stressors (animal may mask pain - white coat effect)
- different types of pain (acute, chronic, etc.)
Is this cat fearful or painful?
- hunched, squinting, not looking at person in the post op picture
- fearful animals will still look at you & be curious of what is going on while painful ones may not
Why might someone use a pain assessment tool?
- increases objectivity & accuracy
- improves consistency of pain recognition
- assesses response to treatment
- ensures that pain is prioritized
- quantify pain
What does a pain assessment tool need?
NEEDS AN OUTCOME MEASURE!
Why should we be pain scoring our patients?
- imagine the treatment of your pain was in the hands of someone who neither speaks your language nor understands what it is to be human; you are at the mercy of that individual
- that well-meaning individual could undertreat you pain & leave you in agony or overtreat your pain leaving you groggy, dysphoric, nauseous, etc.
- assessment is the only way your caregiver can effectively & dynamically manage your comfort
What is important in a pain assessment tool?
- USER FRIENDLY (quick & easy, no lengthy training required
- score linked to an INTERVENTION TOOL
- VALID (measures what it is intended to measure)
- RELIABLE (produces the same score when an unchanging subject is measured at 2 time points by the same observer or by 2 observers at one time point (intra- & inter-rater reliability))
- RESPONSIVE (identifies clinically relevant changes (increase in pain/response to treatment))
What is a preventive (preemptive) scoring system?
- score is assigned according to level of pain that that animal is believed to experience
- categories: none, mild, moderate, or severe
- not useful to treat individual patient
- simple to use
- allows preventive analgesic planning
What are the anticipated levels of pain associated w/ various surgical procedures, illness, or injuries?
- mild pain (early, resolving, simple conditions)
- mild to moderate pain (castration, minor dental procedures, minor lacerations, cystitis, otitis)
- moderate pain (urethral obstruction, laparotomy, ovariohysterectomy, C-section)
- moderate to severe pain (osteoarthritis, acute polyarthritis, peritonitis, hollow organ distension, URETERAL or URETHRAL or BILIARY OBSTRUCTIONS, multiple dental extractions, thoracotomy)
- severe to excruciating pain (multiple fractures, limb amputation, necrotizing pancreatitis)
Which scales are subjective or unidimensional?
- simple descriptive scale (SDS)
- numerical rating scale (NRS)
- visual analog scale (VAS)
- dynamic interactive visual analog scale (DIVAS)
What is the simple descriptive scale?
- most basic & easy to use
- not validated
- four to six descriptors (no pain to worst pain)
- scales are nonlinear
- definitions of descriptive words are open to different interpretations
- extremely subjective & lack of sensitivity to detect small changes in pain
What is the numerical rating scale?
- similar to SDS
- implies equal difference or weighting between each category
- ‘discontinuous’ scale
What is the visual analogue scale?
- horizontal line (10 cm) representing pain experience
- 0 = no pain, 10 = worst possible pain
- segmental dividers or descriptors (bias?)
- is extensively used in human pain assessment & completed by patient
- vet med (significant interobserver variability (29-36%))
What is the Dynamic and Interactive Visual Analog Scale?
- improvement of the classic VAS
- includes dynamic and interactive assessments of patients (DIVAS 1: observation from a distance, DIVAS 2: interaction; DIVAS 3: palpation of injured area)
- score > 40mm = rescue analgesia
What are the types of multidimensional scales?
- categorized numerical rating scales (University of Melbourne Pain Scale (UMPS); Colorado State University Canine/Feline Acute Pain Scale; Canine Brief Pain Inventor (CBPI))
- multi-dimensional composite pain scales (Glasgow composite measures pain scale; UNESP - Botucatu multidimensional composite pain scale (MCPS))
What are categorized numerical rating scales?
- further development of simple descriptive and numerical rating systems
- observe & interact
- different categories where certain behaviours are chosen & assigned a value
- sum of category is pain score
- species specific
- situation specific
What is the University of Melbourne pain scale (UMPS)?
- designed for clinical use
- multiple descriptors in 6 categories
- based on specific behavioural & physiological responses (physiological data: HR, pupil size, & salivation; behavioural responses)
- total score of 27 (intervention score > 5)
- increased accuracy over VAS, SDS, or NRS
- not validated & labour intensive
- requires baseline data
What is the Colorado State University Canine Acute Pain Scale?
- developed as a teaching tool
- intended for Ca & Fe after trauma or surgery
- 3 categories are assessed & assigned a score of 0-4
- observation (behaviour, body tension) & hands on (palpation)
- practical, user friendly, visually appealing
- space for writing further comments
- not validated
What is the Glasgow Composite Measure Pain Scale (CMPS)?
- first validated canine acute pain scale
- seven behavioural categories w/ 47 descriptors (behaviour, reactions towards people, posture, mobility, activity, response to auscultation, treatment of the painful area, & vocalizations)
- too time consuming
- useful research tool but not feasible in clinical environment
What is the CMPS - short form?
- high practicality & clear repeatable format
- for assessment of acute pain (orthopedic & soft tissue surgery, medical conditions)
- behavioural assessment: observation, mobility (if appropriate), palpation, overall assessment)
- reduced interobserver variability
- validated (has been tested at multiple hospital settings)
- intervention score
What are the 6 behavioral categories and how many descriptor options are there within them in the CMPS - short form?
- posture
- activity
- vocalization
- attention to wound or painful area
- demeanor
- response to touch
+ or - mobility
What is the maximum score in the CMPS - short form?
20/24 (24/24 if mobility is included)
What level do we intervene with analgesia in the CMPS - short form?
6/24 or 5/20
What is the UNESP - Botucatu Multidimensional Composite Pain Scale (MCPS)?
- validated for cats undergoing OHE (total of 10 different categories)
- 4 broad categories (psychomotor changes, protection of the wound area, physiologic variables, vocal expression of pain)
- total score 0/30
- 33% of total score empirical selected as point for intervention
What is the cow pain scale?
- 7 behaviours evaluated
- intervention score is 5/14
What are facial expression scoring systems/Grimace Scale?
- identify & assess the severity of pain
- first used in research setting (mouse & rat grimace scales)
- developed for rabbits, horses, sheep, pigs, ferrets, etc.
- easy to use (minimal time & training required)
- often incorporated in multidimensional pain measures (Fe, Eq) or as a standalone assessment
What are facial action units?
- orbital tightening
- ear position
- cheek bulge
- nose bulge
- whisker position
What is the horse grimace scale (HGS)?
- composite and simple descriptive scale
- 6 facial parameters w/ well defined categories (0-2)
- 0 to 2 (no pain present to moderately to obvious)
- good reliability and validity
- other emotional states dont change score significantly
- easy and quick to use (< 2 min)
- has not been validated against an independent data set
How is chronic pain assessment done?
- important to use owner as proxy (owner questionnaire)
- subtle behavioural disturbances may be masked by fear, excitement, or anxiety in clinic setting
- some examples are the HELSINKI CHRONIC PAIN INDEX (HCPI), CANINE BRIEF PAIN INDEX (CBPI; validated for canine OA & osteosarcoma), LIVERPOOL OSTEOARTHRITIS (OA) IN DOGS (validated for elbow arthritis), FELINE MUSCULOSKELETAL PAIN INDEX, & CLIENT SPECIFIC OUTCOME MEASURES (CSOMf) - feline
What are clinical measurement instruments for chronic pain assessment?
- evaluate behaviours in natural setting (going up or down stairs, eating, grooming, ability to jump in the car, difficulty in rising, and inappropriate urination or defecation)
- useful to assess effect of treatment
What is the Canine Brief Pain Inventor (CBPI)?
- chronic pain (osteoarthritis and bone cancer)
- designed to record owner’s assessment
- assess pain severity and how pain interferes with daily life or function
What is the feline musculoskeletal pain index?
Measures impact of osteoarthritis on the domains of
- PAIN (adverse sensory and emotional experience)
- MOBILITY (quality of moving freely)
- ACTIVITY (ability to perform specific activities)
- AFFECTIVE EFFECTS (mood, as perceived by those caring for the cat)
What is the Client Specific Outcome Measures (CSOMf) - feline test?
- owners are interview BY A TRAINED INDIVIDUAL to identify at least 3 ACTIVITIES THAT THEIR CAT DOES MOT DO AS WELL ANYMORE OR HAS RECENTLY STOPPED DOING
What are ways to analyze gait?
force plates or pressure mat walkways
How do force plates or pressure mat walkways work?
- objective methodology to evaluate limb motion
- commonly used in research and referral facilities
- not practiced as an everyday clinical diagnostic tool (expense, space, maintenance, trained personnel)
- force plate is difficult to interpret in the presence of multiple arthritic joints
- helpful in detection of changes in lameness but not stiffness
What are accelerometers or activity monitors?
- objective, non-invasive, portable
- able to evaluate active movement at home
