Assessment Flashcards
Definition of pain. Why it is important to measure pain adequately?
Pain is a subjective experience having behavioural and autonomic manifestations
Measured by:
o Pain thresholds
o Self-reports
o Behavioural measures (pain behaviour)
o Brain and autonomic changes (Lecture 4)
Pain threshold and tolerance threshold definition and methods
Pain threshold: minimum amount of stimulation that reliably evokes a report of pain.
Pain tolerance threshold: time that a continuous stimulus is endured, or the maximally tolerated intensity.
Method of limits (classical approach) - series of ascending and descending stimuli, pps indicates the first stimulus that causes pain, plus another stimulus. Average
Marstock’s modification for thermal pain - Thermal pain, temp increased continuously, button to stop stimulus when it reaches pain. - Dependent of the motor response to press the button
Method of Adjustment: tune the stimulus intensity to painful level - pps changes the stimulus to a painful stimulus
Method of Constant Stimuli: stimuli of fixed intensity are presented in random order - Stimuli that produce pain are averaged
+Simple to administer
- Limited to methods that will not cause tissue damage
Cold pressor test: T[s] to endure cold pain
Tourniquet ischaemia: T[s] to endure ischemic pain - can use a standard blood pressure cuff
-Not suitable for clinical pain
-dependent on reaction time
Quantitative sensory testing
TSA2 - assess all thresholds (Warm threshold
Cold threshold, Heat pain threshold, Cold pain threshold, Vibration threshold)
+ Diagnostic value
+ Phenotyping patients based on QST profiles
- Does not measure spontaneous
background pain
Self-report instruments:
types, and advantages/disadvantages
Categorical scale ([no - yes], [no - mild - strong] and Numerical scales Ordinal scale: a number is assigned to the pain • Simple to use, suits well for rapidly changing pain, sensitive to pain intensity • The boundaries between categories (levels) are not known and are only assumed to be equal • Tendency to stereotyped responses
Although verbal rating scales and numerical rating scales are simple to administer and have
demonstrated reliability and validity, the advantages associated with visual analogue scales make visual analogue scales the measurement instrument of choice when a unidimensional measure of pain is required.
Visual analogue scales
• Ratio scales, pain is represented as continuum that is matched with some other modality
• Subjects are given a reference continuum (intensity of sound, light, length of line)
• The position of certain pain intensity on the continuum is proportional to the pain continuum
+Sensitive to pharmacological and non-pharmacological procedures that alter the experience of acute burn pain (Choinière et al 1990) and postoperative pain (Jensen et al 2002, Katz et al 2003), as well as chronic non-malignant pain (Becker et al 2000, Price et al 1983).
-Evidence suggests that elderly patients with chronic pain make fewer errors on a verbal rating scale than on a visual analogue scale (Gagliese & Melzack 1997),
and that the visual analogue scale may not be as sensitive in detecting age differences in postoperative pain as are other measures (Gagliese & Katz 2003).
-The main disadvantage of visual analogue scales, numerical rating scales and verbal rating
scales is the assumption that pain is a unidimensional experience that can be measured with a single-item scale (Melzack 1975). Although intensity is without a doubt a salient dimension of pain, it is clear that the word pain refers to an endless variety of qualities
Combined verbal-numeric instruments
MPQ
A three-part pain assessment tool that measures several dimensions of the patient’s pain experience
The first part consists of an anatomic drawing of the human form on which the patient marks where his or her pain is located.
The second part allows the patient to record the intensity level of his or her current pain experience.
The third asks patients to review this list of pain descriptors and circle the ones that serve to best describe his or her current pain experience. (Sensory dimension: Affective dimension: Evaluative: Miscellaneous)
Each part or dimension of the MPQ is individually scored and a cumulative total score is also recorded. The present pain intensity, the number-word combination chosen as the indicator of overall pain intensity at the time of administration of the questionnaire.
Evidence of the stability of the
McGill Pain Questionnaire comes from a study of patients with chronic low back pain who completed the McGill Pain Questionnaire on two occasions separated by several days (Love et al 1989). The results showed very strong test-retest reliability
More recently, study of 120 patients with rheumatoid arthritis showed a stable pattern of scores across three pain assessments over a 6-year period (Roche et al 2003).
Turk and coworkers examined the internal structure of the McGill Pain Questionnaire by using techniques that avoided the problems of most earlier studies and confirmed the three (sensory, affective and evaluative) dimensions (Turk et al 1985).
Pearce & Morley (1989) provided further confirmation of the construct validity of the McGill Pain Questionnaire using the Stroop colour-naming task with chronic pain patients
Behavioural methods: reasons for their use, types of pain behaviour, advantages/disadvantages
Pain manifests in behavioural changes (acquiring help, giving a sign of warning)
Pain behavior: any behaviour informing that pain is being experienced (Forcyde, 1976)
Analysis helps to pinpoint the pain problem, enables to set the baseline level of behaviour against which the effects of treatment will be compared.
Types of pain behaviour - low social interactions, use of support (cane or walker), verbal pain statements, avoiding the use of a limb where otherwise appropriate.
Observation methods
Continuous observation of the whole behaviour in a variety of situations
o + complexity and stream of behaviour
o - time consuming and expensive
o - complicated data analysis (scoring)
Duration measure: time spent with certain behaviour
Frequency counts: number of instances of each target behaviour
Inter-observer reliability : r = ~ 0.8
Test-retest reliability : r = 0.5 - 0.7
Validity:
Concurrent: correlates well with self-reports
Construct : comparisons of ratings from trained and untrained (naïve) observers
Discriminant : features of behaviour differentiating pain patients from healthy subjects
Keefe, 2001. Advantages o Used to pinpoint important features of pain o Can be realized in natural settings o Unbiased Disadvantages o Time consumimg o Need for observer training o Complements rather than replaces the self report instruments
Facial expressions of pain: basic principles and advantages/
disadvantages
Darwin (1872): facial expressions of emotions including pain
Facial pain expressions: inborn patterns of facial activity modified by social and family influences
Less dependent on subject’s willingness to admit pain, and not confound by labels that the subject never experienced (“excruciating pain”)
- Brow lowering
- Narrowing of the eye orbit
- Raising the cheek
- Eyes closed or blinking
- Raising the upper lip
- Parting the lips or dropping the jaw
Instruction to exaggerate pain leads to increased intensity of normal pain Action Units in FACS
Instruction to inhibit pain did not produce clear elimination of painful face (Prkachin, Pain, 114: 328-338, 2005)
Facial Action Coding System (Ekman and Friesen, 1978) is used to measure Action Units (small movements of facial structures) in an objective manner.
Pain assessment in people with communication disabilities: explain
the importance of assessment and
type of people at risk
People with inability to communicate pain show brain responses to pain just as able people
Kassubek et al. 2003
Took PET brain scans in 7 patients in persistent vegetative state. Significant increases of blood flow were observed in pain regions.
Risk of underassessment and undertreatment
Untreated pain in people who are unable to communicate pain may worsen their cognitive abilities and executive functions
Risk of overtreatment if the level of pain is overestimated
Pain assessment may reveal an undisclosed medical condition (e.g., fracture, kidney stone)
Lack of communication abilities does not mean that patients would not try to communicate pain
Immaturity: Infants, toddlers, preschool children.
Disabled and mentally retarded persons: Down’s syndrome, Alzheimer disease, cerebral palsy, sclerosis
Temporary restriction of consciousness: general anesthesia, intoxication, sedatives, muscle paralysing substances
Inability to speak the language, mutism, autism
Six rules for pain assessment and pain management in
nonverbal people (Booker and Haedtke, 2016)
1. Facilitate self-reports in those patients who can respond non-verbally (nodding, eye blinks)
- Identify sources of pain which in other people would cause pain (leads, tubes, monitoring devices), and check if a patient had a pre-existing pain condition (e.g.,
osteoarthritis)
3.Observe indicators of pain (facial, mood, movements, behavioural scales useful
4.Consult any symptoms of pain and changes in mood with a family members,
caregivers, and other health care professionals
5.If clear signs of pain present, initiate an analgesic trial (e.g., analgesic drugs
6.If the analgesic trial confirmed pain being present, a collaborative
pain treatment plan will be designed
Pain assessment in people with dementia (Hadjistavropoulus et al. , 2014)
Six rules apply in dementia patients, with slight modifications
• Self-report should be attempted with all patients since patients with dementia can often provide valid self-reports of pain. - Adaptations should be made to match the capabilities of the individual (eg, use of simplified language and large fonts)
• Validated standardised observational approaches should be used to decrease the risk of observer bias. Observational methods:
PACSLAC, DOLOPLUS2: specialised observation scales to assess pain in patients with dementia
- Caregiver and other collaborative informant reports should be solicited and can contribute to the assessment process, although concern with accuracy
- Pain assessment during movement is more likely to elicit pain behaviours than pain assessment during rest.
- An individualised approach - pain is assessed on a regular basis and fluctuation from a patient’s normal pattern of scores is recorded.
- Assessment of pain before and after the administration of a pain management intervention is useful
Hadjistavropoulus et al. (2014).
Disturbances of Consciousness (DoC)
(Persistent/Permanent) Vegetative state: state of partial arousal without self awareness (eyes track moving objects, swallowing, smiling,
grunting, moaning in absence of external stimuli)
Unresponsive wakeful state: a modern label for vegetative states
Minimally conscious state: severely altered consciousness in which a minimal but definite evidence of self or environmental awareness is present (follows simple commands, yes/no response,
pursuit eye movements, simple goal-directed movements)
Traumatic brain injury, neurodegenerative disorder, and congenital abnormities of the brain are the main reasons of DoC.
Nociceptive Coma Scale (Schnacker et al., Pain, 2010)
Nociception refers to the basic processing of a noxious stimulus. It is necessary to pain perception but it will not always lead to a conscious experience.
Neuroimaging studies suggest that nociception and pain are mediated by different networks
Recently, a new scale has been developed to assess
nociception and pain in patients with DOC, the NCS
Brief evaluation (1-2 min) of patient’s behaviour at rest
or during nociceptive stimulation. It consisted of
four sub-scales assessing motor, verbal and visual responses to noxious stimuli as well as facial expression, Visual responses are now dismissed.
The NCS has been validated in patients from intensive
care, neurology/neurosurgery units, rehabilitation centres and nursing homes. In a first study behavioural responses to a noxious stimulus (i.e. nail bed pressure) were scored by two raters using the NCS and four other scales previously validated for non-communicative patients. Results demonstrated good inter-rater reliability and good concurrent validity for the NCS total scores and sub-scores.
Using a PET scan, a significant correlation was found between NCS-R total scores and brain metabolism in the ACC. Suggesting that the NCS-R is at least partially related to cortical pain processing and, hence, may constitute an appropriate behavioural tool to assess, monitor and treat nociception and pain in non-communicative patients with DOC.
