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Assessment and Measurement of Acute Pain in Children

R. Tabacaru
Bucharest, Romania

 

Correspondence

Radu Tãbãcaru

Anesthesia and Intensive Care Dept. 

Maria Curie Children`s Hospital Bucharest;

e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

 

*For preparation of this document we used data from Australian and New Zealand College of Anesthetists, Acute Pain Management, Scientific Evidence.

 

Pain is defined by the International Association for the Study of Pain (IASP) as an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage’ Pain is an inherently subjective experience and should be assessed and treated as such. Pain has sensory, emotional, cognitive, and behavioral components that are interrelated with environmental, developmental, sociocultural, and contextual factors. Acute pain is defined as ‘pain of recent onset and probable limited duration.

It usually has an identifiable temporal and causal relationship to injury or disease’ Chronic pain ‘commonly persists beyond the time of healing of an injury and frequently there may not be any clearly identifiable cause’ The most common type of pain experienced by children is acute pain resulting from injury, illness, or, in many cases, necessary medical procedures. Special attention is needed for appropriate assessment and management of pain when caring for unconscious patients, preverbal or developmentally delayed children, and individuals with impaired communication skills due to disease or language barriers.

Psychological aspects of acute pain

Pain is an individual, multifactor experience influenced by culture, previous pain events, beliefs, mood and ability to cope. It may be an indicator of tissue damage but may also be present in the absence of an identifiable cause. Pain is not a directly observable or measurable phenomenon, but rather a subjective experience with sensory and affective elements which has a variable relationship with tissue damage. In this sense, pain is a psychological phenomenon.

The factors that contribute to pain as an experience may include somatic (physical) and psychological processes, as well as contextual factors, such as situational and cultural considerations. Pain experience may be seen as the result of a dynamic interaction between psychological, social and path physiological variables Particular psychological contributors to the experience of pain include the process of attention, other cognitive processes (e.g. memory/learning, thought processing, beliefs, and mood), behavioral responses, and interactions with the person’s environment.

Assessment

The assessment and measurement of pain are fundamental to the process of assisting in the diagnosis of the cause of a patient’s pain, selecting an appropriate analgesic therapy and evaluating then modifying that therapy according to the patient’s response. Pain should be assessed within a biopsychosocial model which recognizes that physiological, psychological and environmental factors influence the overall pain experience.

Fundamentals of a pain history

  1. Site of pain 
  2. Circumstances associated with pain onset
  3. Character of pain
  4. Intensity of pain
  5. Associated symptoms (e.g. nausea)
  6. Effect of pain on activities and sleep
  7. Treatments
  8. Relevant medical history
  9. Factors influencing the patient’s symptomatic treat

Measurment

The definition of pain underlies the complexity of its measurement. Pain is an individual and subjective experience modulated by physiological, psychological and environmental factors such as previous events, culture, prognosis, coping strategies, fear and anxiety. Therefore, most measures of pain are based on self-report

There are no objective measures of ‘pain’ but associated factors such as hyperalgesia (e.g. mechanical withdrawal threshold), the stress response (e.g. plasma cortisol), behavioral responses (e.g. facial expression), functional impairment (e.g. coughing, ambulation) or physiological responses (e.g. changes in heart rate) may provide additional information. Recording pain intensity as ‘the fifth vital sign’ aims to increase awareness and utilization of pain assessment and may lead to improved acute pain management. Regular and repeated measurements of pain should be made to assess ongoing adequacy of analgesic therapy.

One-dimensional measures of pain

A number of scales are available that measure either pain intensity, or the degree of pain relief following an intervention.

Categorical scales

Categorical scales use words to describe the magnitude of pain or the degree of pain relief. The verbal descriptor scale (VDS) is the most common example (e.g. using terms such as none, mild, moderate and severe). Pain relief may also be graded using a VDS none, mild, moderate and complete. There is a good correlation between descriptive verbal categories and visual analogue scales.

Numerical rating scales

Numerical rating scales have both written and verbal forms. Patients rate their pain intensity on the scale of 0 to 10 where 0 represents ‘no pain’ and 10 represents ‘worst pain imaginable’, or their degree of pain relief from 0 representing ‘no relief’ to 10 representing ‘complete relief’. Visual analogue scales consist of a 100 mm horizontal line with verbal anchors at both ends. The patient is asked to mark the line and the ‘score’ is the distance in millimeters from the left side of the scale to the mark. VAS are the most commonly used scales for rating pain intensity, with the words ‘no pain’ at the left end and ‘worst pain possible’ at the right, while VAS used to rate pain relief have the verbal anchors ‘no pain relief’ and ‘complete pain relief’. VAS can also be used to measure other aspects of the pain experience (e.g. affective components, patient satisfaction, side effects).VAS ratings of greater than 70 mm are indicative of ‘severe pain’ and 0-5 mm ‘no pain’, 5-44 mm ‘mild pain’ and 45-74 ‘moderate pain’. These scales have the advantage of being simple and quick to use, allow for a wide choice of ratings and avoid imprecise descriptive terms. However, the scales require more concentration and coordination, are unsuitable for children under 5 years and may also be unsuitable in up to 26% of adult patients.

Scales used for pain measurement in children

Scale Age Range Pain Utility
Acute pain
neonate

NIPS

CRIES

< 1 year

0-6 months full term

0-7

0-10

>3

 

Procedural

Postoperative 

Composite
scales

CHEOPS

COMFORT

 

1-7 years

newborn- adolescent

4-13

8-40

> 4

> 26

Postoperative,
procedural

Postoperative 0-3 years 

Self report

Facial Pain
Scale

 POKER
CHIPS

4-16 years

4-8 years

6 faces

4 chips = pieces of hurt

Postoperative

 

Neonatal/Infant Pain Scale (NIPS) - (Recommended for children less than 1 year old) - A score greater than 3 indicates pain.

 Pain Assesment Score 

 Facial Expression

 0- relaxed muscles

1- grimace

 

Restful face, neutral expression

Tight facial muscles; furrowed brow, chin, jaw, (negative facial expression
– nose, mouth and brow)

 

 Cry

0 - No cry

1-  Whimper

2- Vigorous Cry 

 

Quiet, not crying

Mild moaning, intermittent

Loud scream; rising, shrill, continuous (Note: Silent cry may be scored if
baby is intubated as evidenced by obvious mouth and facial movement. 

 

 Breathing Patterns

0 - Relaxed

1 - Change in breathing 

 

Usual pattern for this infant

 Indrawing, irregular, faster than usual; gagging; breath holding

 

 Arms

0 - Relaxed/Restrained

1 - Flexed/Extended 

 

No muscular rigidity; occasional random movements of arms

Tense, straight legs; rigid and/or rapid extension, flexion 

 

 Legs

0 - Relaxed/Restrained

1 - Flexed/Extended 

 

No muscular rigidity; occasional random leg movement

Tense, straight legs; rigid and/or rapid extension, flexion 

 

 State of Arousal

0 - Sleeping/Awake

1- Fussy

 

Quiet, peaceful sleeping or alert random leg movement

Alert, restless, and thrashing 

 

 

CRIES neonatal post-op pain measurement score (a pain scale used to assess pain in infants 0-6 months)

0 1 1 Score
Crying None High pitched Inconsolable
Requires O2 for sat
> 95%
No < 30% > 30%
Increased vital
signs
HR and BP = or <
preop
HR and BP increased
< 20% preop
HR and BP increased
> 20% preop 
Expression None Grimace Grimace/Grunt
Sleepless No Wakes at frequent
intervals
Constantly awake

 

Children's Hospital Eastern Ontario Pain Scale (CHEOPS) - (Recommended for children 1-7 years old) - A score greater than 4 indicates pain.

Item Behavioral Definition Score
Cry

No cry

Moaning

Crying

Scream

1

2

2

3

Child is not crying.
Child is moaning or quietly vocalizing silent cry.
Child is crying, but the cry is gentle or whimpering. 
Child is in a full-lunged cry; sobbing; may be scored with complaint
or without complaint.
Facial

Composed

Facial Grimace

Smiling

1

2

0

Neutral facial expression.
Score only if definite negative facial expression.
Score only if definite positive facial expression.
Child Verbal

None

Other Complains

Pain Complains

Both Complains

Positive 

 

1

1

2

2

0

Child not talking.
Child complains, but not about pain, e.g., “I want to see mommy” of “I am thirsty”.
Child complains about pain.
Child complains about pain and about other things, e.g., “It hurts; I want my mommy”.


Child makes any positive statement or talks about others things without complaint.

Torso

Neutral

Shifting

Tense

Shivering

Upright

Restrained

1

2

2

2

2

2

Body (not limbs) is at rest; torso is inactive.
Body is in motion in a shifting or serpentine fashion.
Body is arched or rigid.
Body is shuddering or shaking involuntarily.
Child is in a vertical or upright position.
Body is restrained.
Touch

No Touching

Reach

Touch

Grab

Restrained

1

2

2

2

2

Child is not touching or grabbing at wound.
Child is reaching for but not touching wound.
Child is gently touching wound or wound area.
Child is grabbing vigorously at wound.
Child's arms are restrained.
Legs

Neutral 

Squirm/Kicking

Drawn Up/Tensed

Standing

Restrained

1

2

2

2

2

Legs may be in any position but are relaxed; includes gentle
swimming or separate-like movements.
Definitive uneasy or restless movements in the legs and/or striking
out with foot or feet.
Legs tensed and/or pulled up tightly to body and kept there.
Standing, crouching or kneeling.
Child's legs are being held down.

 

Verbal numerical rating scales (VNRS) where patients are asked to imagine that 0 represents ‘no pain’ and 10 represents ‘worst pain imaginable’ are simple to administer, give consistent results and correlate well with the VAS

acute pain 1

acute pain 2

 

Multidimensional measures of pain

Rather than assessing only pain intensity, multidimensional tools provide further information about the characteristics of the pain and its impact on the individual. Global scales are designed to measure the effectiveness of overall treatment. One-dimensional tools such as the VAS are inadequate when it comes to quantifying neuropath pain. Specific scales have been developed that identify (and/or quantify) descriptive factors specific for neuropath pain. Validated tools are available for measuring pain in neonates, infants and children, but must be both age and developmentally appropriate. Patients who have difficulty communicating their pain (e.g. cognitively impaired patients) require special attention as do patients whose language or cultural background differs significantly from that of their health care team. In such patients, pain measurement scales must be modified to suit individual patient needs. Regular assessment of pain leads to improved acute pain management. There is good correlation between the visual analogue and numerical rating scales Self-reporting of pain should be used whenever appropriate as pain is by definition a subjective experience. The pain measurement tool chosen should be appropriate to the individual patient; developmental, cognitive, emotional, language and cultural factors should be considered. In the postoperative patient this should include static (rest) and dynamic (e.g. pain on sitting, coughing) pain.

Comfort pain scale

The COMFORT scale is a behavioral, unobtrusive method of measuring distress in unconscious and ventilated infants, children and adolescents. A score of 17-26 generally indicates adequate sedation and pain control.

ALERTNESS

Deeply asleep

Lightly asleep

Drowsy

Fully awake and alert

Hyper-alert

1

2

3

4

5

CALMNESS/AGITATION

Calm

Slightly anxious

Anxious

Very anxious

Panicky 

1

2

3

4

5

RESPIRATORY RESPONSE

No coughing and no spontaneous respiration

Spontaneous response respiration with little or no response to ventilation 

Occasional cough or resistance to ventilator

Actively breathes against ventilator or coughs regularly

Fights ventilator, coughing or choking

1

2

3

4

5

BLOOD PRESSURE (MAP)
BASELINE
Blood pressure below baseline
Blood pressure consistently at baseline
Infrequent elevations of 15% or more (1-3)
Frequent elevations of 15% or more above baseline (more
than 3)
Sustained elevation of >15%

1

2

3

4

5

HEART RATE BASELINE Heart rate below baseline
Heart rate consistently at baseline
Infrequent elevations of 15% or more above baseline (1-3)
Frequent elevations of 15% or more above baseline (more
than 3)
Sustained elevation of >15%

1

2

3

4

5

MUSCLE TONE

Muscles totally relaxed; no muscle tone

Reduced muscle tone

Normal muscle tone

Increased muscle tone and flexion of fingers and toes

Extreme muscle rigidity and flexion of fingers and toes 

1

2

3

4

5

FACIAL TENSION

Facial Muscles totally relaxed

Facial muscle tone normal: no facial muscle tension evident

Tension evident in some facial muscles

Tension evident throughout facial muscles

Facial muscles contorted and grimacing 

1

2/tdptd align=Le style= valign=gsmiddl valign=e style=

3

4

5

Pediatric pain assessment

Pain assessment is a prerequisite to optimal pain management in children and should involve a clinical interview with the child (and/or their parent/career), physical assessment and use of an age- and context-appropriate pain measurement tool.

Pain measurement scales

Verbal self-report is considered to be the best measure of pain in adults. However, although it should be used in children whenever possible, children’s understanding of pain and their ability to describe it changes with age. Therefore measurement tools must be appropriate to the different stages of their development. In older children, age-appropriate scales for selfreport need to consider the child’s ability to differentiate levels of intensity and separate the emotional from the physical components of pain. It is important that a measurement tool be used regularly and uniformly within each centre as staff familiarity and ease of use are major factors in the successful implementation of a pain management strategy.

Physiological measures

Changes in physiological parameters associated with procedural interventions and assumed to indicate the presence of pain include: increases in heart rate, respiratory rate, blood pressure, intracranial pressure, cerebral blood flow and palmar sweating; and decreases in oxygen saturation. Their sensitivity and specificity is influenced by concurrent clinical conditions (e.g. increased heart rate due to sepsis) and other factors (e.g. distress, environment, movement).

Behavioral measures

Noxious stimuli produce a series of behavioral responses in infants that can be used as surrogate measures of pain including crying, changes in facial activity, and movement of torso and limbs, consol ability and sleep state. Crying can be described in terms of its presence or absence, duration and amplitude or pitch. The reliability and validity of behavioral measures are best established for short sharp pain associated with procedural interventions such as heel stick. The specificity and sensitivity of the response can be influenced by habituation, motor development, previous handling and manifestations of other states of distress (e.g. hunger and fatigue). Ten facial actions are included in the Neonatal Facial Coding Scale (NFCS) which was originally validated for procedural pain in neonates and infants. A reduced scale with 5 items (brow bulge, eye squeeze, nasolabial furrow, horizontal mouth stretch and taut tongue) has been found to be a sensitive and valid measure of postoperative pain in infants ages 0-18 months. In infants and young children, behavioral items that predict analgesic demand in the postoperative period are crying, facial expression, posture of the trunk, posture of the legs and motor restlessness

acute pain 3

 

acute pain 4 

Composite measures

Many scales incorporate both physiological and behavioral parameters to determine an overall pain score and may result in more comprehensive measurement. No single scale has been shown to be clearly superior or been universally adopted.

Self-report

Self-report of pain is usually possible by 4 years of age but will depend on the cognitive and emotional maturity of the child. At 4-5 years of age, children can differentiate ‘more’, ‘less’ or ‘the same’, and can use a Faces Pain Scale if it is explained appropriately and is a relatively simple scale with a limited number of options. Between 7 and 10 years of age children develop skills with measurement, classification and seriating (i.e. putting things in ascending or descending order). At 10-12 years of age children can/tdborder-width: 1px; border-color: #d4cece; border-style: solid;center clearly discriminate the sensory intensity and the affective emotional components of pain and report them independently. Verbally competent children aged 12 years and above can understand and use the McGill Pain Questionnaire. As with adults, there can be disagreement between the child’s ratings of pain and the rating given by nurses and medical staff, with the latter groupstd align=Legs often underestimating the severity of the pain.

 

 

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