| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Refresher Courses - Saturday June 9 |
From the Department of Anesthesia, Dalhousie University, IWK Health Centre, Halifax, Nova Scotia, Canada.
Address correspondence to: Dr. Allen Finley, Pediatric Anesthesia, IWK Health Centre, 5850 University Avenue, Halifax, Nova Scotia, Canada B3J 3G9. Phone: 902-428-2708; Fax: 902-428-2709; E-mail: allen.finley{at}dal.ca
I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it, but when you can not measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the state of science whatever the matter may be.
— Lord Kelvin quoted by Lewis Thomas1
In order to manage pain in any patient, it is essential to be able to measure the outcomes of treatment. Without measurement, it is impossible to research new drugs or treatment techniques, just as it is impossible to treat individual patients without knowing whether the treatment is working. Health centre accreditation now requires that processes for assessing and documenting pain be in place,2 and patients and their families are being educated about the need for proper pain assessment and management. The Canadian Pain Society has issued a position paper which states, in part, that "routine assessment is essential for effective management" and that "health professionals have a responsibility to assess pain routinely, to believe patients' pain reports, to document them, and to intervene in order to prevent pain".3
The International Society for the Study of Pain has defined pain as "...an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage...", and goes on to say that "pain is always subjective".4 The gold standard for pain measurement is self-report; the patient's own description of his or her own sensations and the personal interpretation of those feelings. With children, it can be a complex task to acquire that data, and developmental level, behaviour, and family influences must be taken into consideration.
Why are children special?
It has been recognized for almost two decades that children are frequently under-medicated for postoperative and disease pain.5 Although this pattern resulted in part from an unsubstantiated fear of potent analgesics, it was, to a large extent, a result of the failure to recognize the degree, or even the presence, of pain in children. Children often can't or won't express their feelings and degree of pain—if anything, they may underrate their own pain because of fear of the consequences. However, we have a professional obligation and a social responsibility to protect children. Looked at objectively, one cannot imagine a situation in which one would say "it would be a good idea to cause that child some pain", yet health professionals often rationalize the "benefits" either of the pain ("he might as well get used to it"), or of the intervention that is causing the pain. It has never been demonstrated that pain has a beneficial effect, and the evidence for harm from pain itself is mounting. Even brief episodes of pain in the newborn period may have profound long-term consequences. Taddio showed that un-anesthetized circumcision of newborns resulted in increased crying and behavioural response to the pain of the immunization needle four to six months later.6 Anand's landmark work demonstrated the increases in morbidity and mortality that result from inadequate opioid use during and after major surgery in infants.7,8 Thus, it becomes extremely important to ensure that we recognize and treat pain in infants and children to the greatest extent possible, and to do that, we have to measure it. A recent edited text has brought together work by many of the experts in the field.9
Measurement techniques
What patients say...
Self-report is the "gold standard" for pain measurement. The concept that only the patient can really understand what he/she is feeling is embodied in the definition of pain, but self-report in children can be challenging. Clearly, pre-verbal children cannot tell you what they are feeling, but even verbal children may under-rate their pain if they are unsure about the consequences. The child may be afraid of what will happen to him (a needle, a longer hospital stay, a parent who is upset with or disappointed in him) or of what the pain implies ("something bad is going on", "the cancer has come back", "I won't be able to play hockey any more"). Part of the assessment is an explanation of what will be done with the information. Reassuring the child that we need to know how much pain there is "so we can put medicine in the iv tubing to make it better" is a good start to this process. Even teenagers may be difficult to assess, due to a reluctance to express their feelings to an adult.
Self-report of pain is usually measured on a linear scale ranging from "no pain" to "the worst pain imaginable". Although a simple 0 to 10 numerical scale is easy to use and appropriate for adolescents and older children, just as it is for adults, younger children need alternative tools to help them deal with more abstract concepts. For the most part, these have been developed as images of faces in varying degrees of distress. One of the most familiar is the OucherTM, a group of six photographs of children's faces mapped onto a 100-point scale.10 This is available in formats using various ethnic presentations11 and has been widely used, although the photographs entail a poster-size presentation for the scale, making it less practical for use in the hospital. A number of scales have been developed using line drawings of faces, which allows them to be presented in a pocket-sized version. The best validated and theoretically most appropriate is that developed by Bieri and colleagues.12 It is a seven-face scale (scored from 0 to 6), which was developed from children's drawings, has a neutral expression for the "no pain" anchor (rather than a "smiley" face),13 and has ratio scale properties. Other face scales have also been published, and some of them are also in widespread use.14–16
For younger children, the Poker Chip tool is an easy and concrete tool that can be understood by even a three- or four-year-old.17 Four poker chips (or similar, non-swallowable items) are described as "pieces of hurt". Children quickly learn to describe the number of pieces of hurt they feel.
What patients do...
Many children cannot give a verbal report of their pain, either because they are too young, or because of neurological or communication impairment. In this situation, care givers must rely on behavioural tools to identify and rate pain. A number of scales have tried to capture these behaviours in a quantifiable way. The Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) uses a combination of vocal, arm, and body movements to score postoperative pain.18 Similar approaches include the Objective Pain Scale (OPS)19 and the Neonatal Infant Pain Scale (NIPS).20 However, all acute behaviour scales suffer from the same problem, that pain behaviours attenuate over time, making the scale insensitive after the first hour or so postoperatively.21 Although this type of scale may work well for procedure pain or during the first short period of time in the recovery room, it becomes unreliable (and may indicate much lower pain than the child is actually feeling) once the child has gone home or to the nursing unit.
Considerable research has focussed on facial action coding, a technique which uses distinct changes in facial expression (eye squeeze, nasolabial furrow, mouth stretch, etc.) to measure pain responses.22,23 Again, this approach is well-validated in procedure pain, but is very labour-intensive and has not yet been applied to continuing pain. The Premature Infant Pain Profile (PIPP) is a composite measure that captures behaviour, three of the facial actions, and physiological changes to generate a valid pain score for infants in neonatal intensive care.24 The PIPP can be used routinely in a clinical setting, whereas the full Child Facial Action Coding System is rather unwieldy for daily clinical use.
Chambers and colleagues have attempted a different approach, using cues that parents described as indicating pain in their children to construct the Parents' Postoperative Pain Measure (PPPM), which correlates well with child self-report of pain following ambulatory surgery.25 Unlike the CHEOPS or OPS, the PPPM checklist includes changes from the usual for that child in behaviours like eating, sleeping, and playing. As a consequence, it must be used by a parent or someone very familiar with that individual child, not by a health professional. Further studies of the PPPM have supported its construct validity and its extension to use in the two to six year age group.26,27
Children with neurological disease, who are unable to communicate due to cognitive or motor impairment, are at particular risk for untreated pain. In particular, children with cerebral palsy have more pain than the normal population due to muscle spasm, joint dislocations, and gastro-esophageal reflux, and they have frequent surgical interventions. However, they often are unable to express this in a way that care givers can understand, and therefore are less likely to get adequate analgesic treatment.28 Children with autism and developmental delay may also be unable to express pain and thus will suffer more following injury or surgery. Behavioural assessment is also more challenging in these patients, as they may not have a normal range of behavioural expression. Breau has developed a checklist of behaviours in communication-impaired persons that is showing promise as a clinical tool.29 Behaviour groupings include vocal, social, activity, facial expression, and body/limbs. In a preliminary study, the specific parameters that showed significant increase after surgery included idiosyncratic pain movement, shivering, pallor, tears, eating less, and increased sleep. Of interest, moaning and crying were not useful criteria for identifying postoperative pain in this group of patients.30
How their bodies react...
Well-recognized physiological changes occur in response to acute pain. Heart rate and blood pressure usually increase, tearing and sweating occur, and, in the neonate, oxygen saturation may fall.31 Unfortunately, these signs are non-specific and, in any case, do not persist with continuing pain. They may be useful for measuring the impact of procedure or incident pain, but are also affected by fear and anxiety, as well as pain. Most of the research in this area has been done in infants.
Imaging techniques, including functional MRI, PET, and SPECT, are being used to try to understand the mechanisms of pain processing in the brain.32 However, little, if any, of this work has been done in children so far.
Practical application
Whichever tool or combination of tools for pediatric pain assessment are used in a hospital or clinical practice, the most important issue is to ensure that pain measurement becomes a routine part of clinical care, just like taking the temperature or blood pressure. If pain is measured regularly, recorded, and presented to nurses and physicians so that it cannot be overlooked or ignored, then treatment of pain will follow and future pain may be prevented.
References
1 Thomas L. Late Night Thoughts on Listening to Mahler's Ninth Symphony, New York: Viking, 1983: 143–5.
2 Canadian Council on Health Services Accreditation. The AIM project: achieving improved measurement. Draft standards, Ottawa: CCHSA, 1999: 353–4.
3 Watt-Watson JH, Clark AJ, Finley GA, Watson CPN. Canadian Pain Society position paper on pain relief. Pain Research and Management 1999; 4: 75–8.
4 Task Force on Taxonomy. Classification of chronic pain: descriptions of chronic pain syndromes and definitions of pain terms. Seattle: IASP Press, 1994.
5
Schechter NL, Allen DA, Hanson K. Status of pediatric pain control: a comparison of hospital analgesic usage in children and adults. Pediatrics 1986; 77: 11–5.
6 Taddio A, Goldbach M, Ipp M, Stevens B, Koren G. Effect of neonatal circumcision on pain responses during vaccination in boys. Lancet 1995; 345: 291–2.[Medline]
7 Anand KJS, Aynsley-Green A. Does the newborn infant require potent anesthesia during surgery? Answers from a randomized trial of halothane anesthesia. In: Dubner R, Gebhart GF, Bond MR (Eds). Pain Research and Clinical Management, vol. 3. Proceedings of the 5th World Congress on Pain. New York: Elsevier, 1988: 329–35.
8 Anand KJS, Hickey PR. Pain and its effects in the human neonate and fetus. N Engl J Med 1987; 317: 1321–9.[Medline]
9 Finley GA, McGrath PJ. Measurement of Pain in Infants and Children. Seattle: IASP Press, 1998.
10 Beyer JE. The Oucher: A User's Manual and Technical Report, Evanston, IL: Hospital Play Equipment, 1984.
11 Beyer J, Knott CB. Construct validity estimation for the African-American and Hispanic versions of the Oucher scale. J Pediatr Nurs 1998; 13: 20–1.[Medline]
12 Bieri D, Reeve RA, Champion GD, Addicoat L, Ziegler JB. The faces pain scale for the self-assessment of the severity of pain experienced by children: development, initial validation, and preliminary investigation for ratio scale properties. Pain 1990; 41: 139–50.[Medline]
13 Chambers CT, Giesbrecht K, Craig KD, Bennett SM, Huntsman E. A comparison of faces scales for measurement of pediatric pain: children's and parent's ratings. Pain 1999; 83: 25–35.[Medline]
14 Wong DL, Baker CM. Pain in children: comparison of assessment scales. Pediatr Nurs 1988; 14: 9–17.[Medline]
15 Kuttner L, LePage T. Face scales for the assessment of pediatric pain: a critical review. Can J Behav Sci 1989; 21: 198–209.
16 McGrath PA, de Verber LL, Hearn MT. Multidimensional pain assessment in children. In: Fields HL, Dubner R, Cervero F (Eds). Proceedings of the 4th World Congress on Pain. New York: Raven Press, 1985: 387–4.
17 Hester NO, Foster RL, Kristensen K. Measurement of pain in children: generalizability and validity of the pain ladder and the poker chip tool. In: Tyler DC, Krane EJ (Eds). Pediatric Pain. New York: Raven Press, 1990: 79–84.
18 McGrath PJ, Johnson G, Goodman JT, Schillinger J, Dunn J, Chapman J. CHEOPS: a behavioral scale for rating postoperative pain in children. In: Fields HL, Dubner R, Cervero F (Eds). Proceedings of the 4th World Congress on Pain. New York: Raven Press, 1985: 395–402.
19 Norden J, Hannallah R, Getson P, O'Donnell R, Kelliher G, Walker N. Concurrent validation of an objective pain scale for infants and children. Anesthesiology 1991; 75: A934.
20 Lawrence J, Alcock DS, McGrath PJ, Kay J, MacMurray SB, Dulberg CS. The development of a tool to assess neonatal pain. Neonatal Network 1993; 12: 59–66.[Medline]
21 Beyer JE, McGrath PJ, Berde CB. Discordance between self-report and behavioral pain measures in children aged 3-7 years after surgery. J Pain Symptom Manage 1990; 5: 350–6.[Medline]
22 Grunau RVE, Craig KD. Pain expression in neonates: facial action and cry. Pain 1987; 28: 395–410.[Medline]
23 Chambers CT, Cassidy KL, McGrath PJ, Gilbert CA, Craig KD. Child facial coding system: a manual. Dalhousie University and University of British Columbia: 1996.
24 Stevens B, Johnston CC, Petryshen P, Taddio A. Premature infant pain profile: development and initial validation. Clin J Pain 1996; 12: 13–22.[Medline]
25 Chambers CT, Reid GJ, McGrath PJ, Finley GA. Development and preliminary validation of a postoperative pain measure for parents. Pain 1996; 68: 307–13.[Medline]
26 Finley GA, Chambers CT, McGrath PJ, Walsh T. The parents' postoperative pain measure discriminates between pain and anxiety. Abstracts/9th World Congress on Pain. Seattle: IASP Press, 1999: 196–7.
27 McGrath PJ, Finley GA, Chambers CT, Walsh T. Further validation of the parents' postoperative pain measure: extension to 2-6 year old children. Abstracts/9th World Congress on Pain 1999: 201.
28 McGrath PJ. We all failed the Latimers. Paediatrics and Child Health 1998; 3: 153–4.
29 Breau LM, McGrath PJ, Camfield C, Rosmus C, Finley GA. Preliminary validation of an observational pain checklist for persons with cognitive impairment and inability to communicate verbally. Devel Med Child Neurol 2000; 42: 609–16.[Medline]
30
Finley GA, Breau L, McGrath PJ, Camfield C. Postoperative pain behaviour of neurologically-impaired children. Can J Anesth 2001; 48: A32 (abstract).
31 Sweet SD, McGrath PJ. Physiological measures of pain. In: Finley GA, McGrath PJ (Eds). Measurement of Pain in Infants and Children. Seattle: IASP Press, 1998: 59–81.
32 Anand KJS. Neurophysiological and neurobiological correlates of supraspinal pain processing: measurement techniques. In: Finley GA, McGrath PJ (Eds). Measurement of Pain in Infants and Children. Seattle: IASP Press, 1998: 21–46.
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
