Pre-hospital pain management in children (CPD Article)

Words 3064

List of Changes Made:

1. Reference to WHO pain ladder added. And paragraph added in ‘managing pain’ re. analgesic ladder.

2. Reference Links Broken: Both links were not broken and were accessible by myself. I have for ease changed the IASP 2005 refence from the direct PDF link to the website link. The abdominal pain in children reference has not been changed.

3. Reflection question 1 changed.4. Paragraph added re. abuse in children to ‘common causes of pain in children’ section.5. Regarding the lean towards the use of US and Australian articles, I partly disagree with the

reviewers. One of the leading individuals in pre-hospital pain management is Associate Professor Bill Lord, based at the University of the Sunshine Coast in Australia. My reference to the work of Associate Professor Bill Lord is necessary as he is a paramedic, he has spent the majority of his research career studying pre-hospital pain management and he is a world leader in this field. Also, the pre-hospital evidence base surrounding pain management is sparse, therefore we need to use all available evidence in the most appropriate way. Whilst I appreciate the reviewer’s comments that there should be more references from the UK, namely the British Pain Society and the Royal College of Anaesthetists, and yes I agree, I also feel that we should be using the information that is most relevant, most accessible and easily interpreted and well presented. My Australian reference re. causes of abdominal pain in children is well presented, concise and easy to digest / print / annotate ect. The state of Victoria and especially the Victorian ambulance service are known for producing high quality evidence. The American study I reference regarding pain in children was used due to large numbers involved. There is little UK pre-hospital evidence surrounding pre-hospital pain management in children therefore the use of these references is necessary.

6. Age definition added to ‘What is pain and why do we need to treat it?’ section.7. Melzack and Wall Gate Control Theory added to introduction8. Pharmacokinetic differences between children and adults added to management of pain

section.

Abstract / Overview:

The management of pain is complex, especially in children as age, developmental level, cognitive and communication skills, and associated beliefs must be considered. Pain can have psychological, physical and social consequences which impact on quality of life. Without effective pain treatment, children may suffer long-term changes in stress hormone responses and pain perception and are at risk of developing post-traumatic stress disorder. Further, the pre-hospital setting adds an additional level of complexity as environmental factors have to be taken into consideration. This article will

help shed light on a number of difficulties faced when managing pain in children and how to overcome them.

Learning Outcomes:

After completing this module, the paramedic will be able to:

Understand common causes of pain in children. Assess children suffering pain. Appropriately measure pain. Manage pain adequately. Document the pain management process accurately.

Clinical Scenario

It’s a cold and wet Saturday afternoon when you are dispatched to a 9 year old male with a suspected lower limb injury. The incident location is a local football field. On your arrival you are greeted by the coach and a few other parents who inform you he has twisted his ankle badly. Due to the weather conditions you take the stretcher, scoop, Entonox, vacuum splint and a few blankets onto the pitch in anticipation of moving to the ambulance. You find the patient in the supine position with his hands covering his face, screaming. The history of the complaint involves the patient entering a tackle with another player, he heard a ‘crack’ and felt a sudden surge of pain to his right ankle. Unable to weight bear he remained on the floor. You undertake a quick primary survey and then expose / examine the ankle which is swollen and painful to touch. The pedal pulse is present, there are no breaks to the skin and distal movement and sensation is intact. You suspect a fractured distal tibia / fibular due to the significant swelling. A pain score is obtained (10/10) using the numeric pain rating scale. You make the decision to administer Entonox, apply a vacuum splint, scoop onto the stretcher and move onto the back of the ambulance to escape the adverse weather conditions.

You obtain the following clinical observations (Table 1):

Table 1. Clinical Observations

Observation ResultRespiratory Rate 24 breaths per minute

Heart Rate 130 beats per minuteBlood Pressure 110/78 mmHgTemperature 36.2oC (tympanic)

Oxygen Saturations 100%Glasgow Coma Scale 15/15Electrocardiogram Sinus Tachycardia

Blood Glucose 5.2 mmol/LPain Score (Second) 7/10 NPRS

Having moved the patient, you re-examine the ankle to ensure there is no limb threat or open fracture. You examine for distal circulation, movement and sensation and for broken skin / protruding bone. You then perform a full top to toe examination to rule out other injuries. Having initially managed the pain with Entonox and still scoring the pain 7/10, with parental permission you gain intravenous (IV) access, check your JRCALC 2016 and administer 3mg morphine sulphate IV. After a further 10 minutes the patient’s pain has reduced to 3/10 and he appears much more comfortable. You convey the patient to the local emergency department accompanied by his mother. You take a final pain score on arrival at hospital which has remained unchanged at 3/10.

What is pain and why do we need to treat it?

Pain is ‘an unpleasant sensory and emotional experience associated with actual or potential tissue damage’ (International Association for the Study of Pain (IASP) 1994). Due to the complex nature of pain, a number of theories exist which seek to explain this phenomenon. Melzack and Wall (1965) proposed gate control theory, which is arguably the most accepted, combining earlier concepts of specificity and pattern theory. This theory explains that pain is controlled by a ‘gate’ and that certain factors will open and close the gate. Gate control theory accepts the disparity between pain stimuli and pain perception and that psychological factors such as previous experience of pain, level of concentration and emotion can influence the ‘gate’ and subsequently the amount of pain perceived.

According to international human rights law (Lohman, Schleifer and Amon, 2010) and the World Health Organisation (WHO, 2015) all countries must provide pain treatment medication as a core obligation under the right to health. The management of pain is complex, especially in children (age <18) as age, developmental level, cognitive and communication skills, and associated beliefs must be considered (Srouji, Ratnapalan and Schneeweiss, 2010). Pain can have psychological, physical and social consequences which impact on quality of life (Lohman et al., 2010). Without effective pain treatment, children may suffer long-term changes in stress hormone responses and pain perception (Finley, Franck, Grunau et al., 2005) and are at risk of developing post-traumatic stress disorder (Sheridan, Stoddard, Kazis et al., 2014; Saxe, Stoddard, Courtney et al., 2001).

REFLECTION 1: Do paramedics have a professional obligation treat pain?

Common Causes of Pain in Children

A recent United States study, involving 14 emergency medical services found that from 55,642 calls to patients under 19 years of age, traumatic injury was documented as the presenting complaint in 26% of cases, making it the most frequent presenting complaint (Lerner, Dayan, Brown et al., 2014). They also found that ‘pain non-chest / non-abdomen’, ‘abdominal pain / problems’ and ‘chest pain / discomfort’ was documented in 10.5%, 4.1% and 1.5% of cases, respectively. Although trauma is the most common cause of pain in children in the pre-hospital setting, causes of abdominal pain are also frequent and important to remember. Here are a number of common abdominal pain causes in children:

bowel (gut) problems – constipation, colic or irritable bowel infections – gastroenteritis, kidney or bladder infections, or infections in other parts of the

body like the ear or chest food-related problems – too much food, food poisoning or food allergies problems outside the abdomen – muscle strain or migraine surgical problems – appendicitis, bowel obstruction or intussusception (telescoping of part of

the gut) period pain – some girls can have pain before their periods start poisoning – ingesting domestic products / medication (intentionally or unintentionally).

Adapted from Victorian State Government (2013)

In addition to identifying the cause of pain, pre-hospital clinicians have a duty to recognise signs of potential abuse in children. This includes emotional, sexual, physical abuse and neglect (Brown, Kumar, Millins et al., 2016). Suspicion of physical abuse should be considered in the presence of: delayed reporting of the injury, accidents/injuries in unusual places (chest/abdomen/back, inner thighs) or injury in a non-mobile baby. These examples are by no means exhaustive and any situation where abuse or neglect is suspected, a safeguarding referral should be made according to local guidelines and the receiving department should be made aware of the suspicion and referral.

REFLECTION 2: Why is it important to differentiate between traumatic and medical causes of pain?

Assessing Children Suffering Pain

There are a number of mnemonics that can assist in the assessment of pain. One is OPQRST (Onset, Provokes/Palliates, Quality, Region/Radiates, Severity, Time) (Lord, 2015) and the other SOCRATES (Site, Onset, Character, Radiates, Associated Symptoms, Time / Duration, Exacerbating or Relieving Factors, Severity) (Brown et al., 2016). An in-depth assessment of the pain can help indicate its aetiology and assist in the development of a clinical impression. It’s important to keep an open mind when assessing pain and explore all possible avenues as it’s easy to get ‘tunnel vision’ and focus on the most likely cause.

Pain is a complex and difficult symptom to assess because each patient will experience pain differently depending on their age, gender, prior pain experiences and cultural / social norms (Lord, 2015). It’s also important not to let our own perception of pain influence our assessment of pain as paramedics are likely to underestimate pain (Solomon, 2001).

REFLECTION 3: You attend a 13-year-old male who has fallen down the stairs and presents with a chief complaint of abdominal pain. How would you approach the assessment of pain and would you initially suspect a trauma or medical aetiology, or both?

Measuring Pain in Children

Measuring a child’s pain is paramount. Without measurement, you cannot hope to manage the pain adequately because you have no baseline to know whether the management has been effective or not. With the given scenario, it would have been tempting to quickly administer the Entonox and transfer to the ambulance before taking a pain score. However, without the pre-analgesic pain score the effectiveness of Entonox would be unknown, therefore the clinician would not be able to make an informed decision regarding the next step of the pain management process.

An age appropriate pain management tool should be used. This promotes compliance of self-reporting and prevents the clinician ‘estimating’ the child’s pain. Despite there being no pain assessment tools for children validated in the pre-hospital setting (Brown et al., 2016) it’s acceptable to use tools that have been validated in-hospital.

For this scenario the 11-point Numeric Pain Rating Scale (NPRS) was used due to the patient’s age and cognitive ability. This tool should be understood and easily interpreted by children aged 8 years and older (von Baeyer, Spagrud, McCormick et al., 2009). Older children may also use the Adjective Response Scale (ARS) where children give a verbal response of “None”, “Slight”, “Moderate”, “Severe”, “Agonising” (Lord, 2015). This tool however is limited by cultural and language barriers and is less sensitive to small changes in pain. Also, the Visual Analogue Scale (VAS) is well validated in in children aged 6 and over (Ho, Spence and Murphy, 1996). The 10cm line is a common version with the words “no pain” and “Worst Pain” at either end of the scale. The patient is then asked to point to where their pain matches the line.

For children aged 3 years and older the Wong-Baker (2017) faces scale is a validated tool that can be used, see Figure 1. This tool has been developed and revised over a number of years and now coincides with the 11-point NPRS with scores of 0, 2, 4, 6, 8 and 10 as opposed to the original 0-5.

Figure 1 – Wong-Baker FACES ® Pain Rating Scale

Wong-Baker FACES Foundation (2017)

The Oucher!TM scale (Beyer, Villarruel and Denyes, 2009) combines the VAS and the Wong-Baker concept to create a multifunctional tool for children aged 3 – 12 years. This tool is unique as the pictures are of real children and a variety of ethnicities are available to choose from.

Finally, for pre-verbal or older children with reduced cognitive ability the FLACC (Face, Legs, Activity, Crying and Consolability) (Merkel, Voepel-Lewis, Shayevitz et al., 1997) scale is a useful objective tool (Table 2). This results in a pain score of between 0 and 10.

Table 2 – FLACC Pain Scale

ScoreBehaviour 0 1 2

Face No particular expression or smile

Occasional grimace or frown, withdrawn,

disinterested

Frequent to constant quivering chin, clenched jaw

Legs Normal position or relaxed

Uneasy, restless, tense

Kicking or legs drawn up

Activity Lying quietly, normal position, moves easily

Squirming, shifting, back and forth, tense Arched, rigid or jerking

Cry No cry (awake or asleep)

Moans or whimpers; occasional complaint

Crying steadily, screams, sobs,

frequent complaints

Consolability Content, relaxed

Reassured by touching, hugging or

being talked to, distractible

Difficult to console or comfort

Australian Government (2013)

Another useful pre-verbal pain scale is EVENDOL (Fournier-Charriere, Tourniaire, Carbajal et al., 2012), which has been validated within the emergency department for use on children aged 7 years and under.

When measuring pain, it’s important to know when a ‘clinically meaningful’ reduction in pain is achieved. A pain score reduction of 2 or more out of 11 is often deemed effective or ‘clinically meaningful’ (Bulloch and Tenenbein, 2002; Farrar, Young, LaMoreaux et al., 2001; Farrar, Berlin and Strom, 2003; Myrvik, Brandow, Drendel et al., 2013; Whitley and Bath-Hextall, 2017). However, given this clinical scenario, even though a pain score reduction of 3 was achieved with Entonox which is clinically meaningful, this was not a reason to stop and not progress up the ‘analgesic ladder’ (WHO, 1986), as the patient was still suffering severe pain.

REFLECTION 4: Pain scales are only useful when used correctly and in the manner for which they were developed. What is the risk of using a pain scale inappropriately?

Managing Pain Adequately

Pharmacological

The analgesic ladder was first proposed by the World Health Organisation (WHO) (1986) for adult patients suffering cancer. Since it’s inception other healthcare fields have adopted this ladder, including ambulance services. The ladder proposed a systematic approach to managing pain, starting with non-opioid medication and progressing to weak and finally strong opioid medication if the pain persists or increases. Since then, it has been proposed that for children suffering persistent pain from medical illness, a ‘two-step’ approach be taken (WHO, 2012). This involves 1) treatment of ‘mild’ pain with paracetamol and/or ibuprofen and 2) treatment of ‘moderate to severe’ pain with a strong opiate. This negates the need for a mild opiate such as codeine and mitigates the delay in administering strong opiates for moderate to severe pain when using the original ‘ladder’ approach. Arguably, this approach is more relevant to pre-hospital pain management, however this recommendation is based on ‘very low quality’ evidence, is out of context and therefore further research would be ideal.

A number of medicines are available to paramedics which can be used for the treatment of pain. These include paracetamol tablets, paracetamol suspension, ibuprofen tablets, ibuprofen suspension, Entonox, oral morphine and morphine sulphate (IV). Other medicines may be available through local patient group directions. A recent study determined the clinical effectiveness of these medicines when treating injured children and found that they all produced a clinically meaningful reduction in pain except paracetamol tablets (ibuprofen not included in study) (Whitley and Bath-Hextall, 2017) (See Figure 2).

Figure 2. Median pain score reductions per analgesic for pre-hospital injured children

(Whitley and Bath-Hextall, 2017)

However, there are advantages and disadvantages to a number of these medicines. Paracetamol and oral morphine can be administered with ease, yet both are slow acting drugs, especially oral morphine due to gastric wastage and reduced absorption times (Brown et al., 2016). Oral morphine has a bioavailability of 23.9% (Hoskin, Hanks, Aherne et al., 1989; Halbsguth, Rentsch, Eich-Hochli et al., 2008) and maximum plasma concentrations are seen at 45 minutes post-administration (Hoskin et al., 1989). Although a potent analgesic, oral morphine takes a significant time to reach its peak effect. Considering the low bioavailability, administering 10mg of oral morphine is roughly equivalent to 2-3mg intravenous morphine.

Intravenous morphine sulphate has a bioavailability of 100%, and takes effect within a minimum of 2-3 minutes, with the maximum effect taking place between 10–20 minutes (Brown et al., 2016). However, the process of peripheral intravenous cannulation is painful and notoriously difficult in paediatrics, especially younger children (Reigart, Chamberlain, Eldridge et al., 2012). Entonox is an effective analgesic, quick and easy to administer with its maximum effect taking place between 2-3 minutes, and the effects wear off within 30 minutes (BOC, 2015). However, some may find Entonox inadequate as one study showed inhaled Entonox was effective in the majority of patients (80.5%), leaving the remainder in pain (Heinrich, Menzel, Hoffmann et al., 2015). Furthermore, inhaled analgesics are difficult to administer to distressed and uncooperative children (Murphy, Barrett, Cronin et al., 2014).

It is important to remember that whilst children are not small adults, often the effects of drugs on children are similar to that of adults (Stephenson, 2005). That being said, there are a number of pharmacokinetic differences that separate children and adults, meaning the same dose per kg cannot be transcribed from adults to children. A number of these differences are

‘immature renal function in infants

slower gastrointestinal but faster intramuscular absorption in infancy larger liver to body weight ratio in infants more body water vs. lipid in early life limited protein binding in infants’

Stephenson (2005) pg 671.

Therefore, it is of the upmost importance that you follow local and national guidelines when calculating analgesic dosages in children.

Non-pharmacological

This form of intervention is extremely potent in children and should never be overlooked or underestimated. Types of non-pharmacological intervention include;

psychological, where the presence of a parent or distraction techniques are used. dressings, especially for burns where the cooling effect helps to relieve pain. splinting, where slings, vacuum, box or traction splints could be used, along with improvised

cushion or blanket placement to help reduce movement of the painful area.

(Brown et al., 2016)

The key here is accurate documentation, which we will come onto shortly, as the use of distraction may seem minor or even natural and therefore overlooked as an important intervention to document, but documentation of pain scores along with the use of non-pharmacological interventions helps to create a more informative and complete clinical record.

REFLECTION 5: What are the benefits of combining pharmacological and non-pharmacological interventions?

Accurate Documentation

As the saying goes: “if you don’t document it you didn’t do it”. Clearly the most important aspect of clinical practice is treating the patient to the best of your ability, however it is of the upmost importance that the pain management process is documented accurately. A recent evaluation of pain management in children showed that from 2596 clinical records of injured children in pain, 1663 (64%) could not be used because the vast majority had no pre or post-analgesic pain score documented (Whitley and Bath-Hextall, 2017). Without a pre and post-intervention pain score the effectiveness of the intervention is unknown, therefore is little use to the clinicians you are handing over to and little use to any audit or future research that your clinical record may be involved in.

Conclusion

Despite pain assessment, measurement and management being challenging in the pre-hospital child, there are ways to manage the process effectively. Performing an in-depth assessment of the pain can help identify the correct aetiology, using an age-appropriate pain scale will promote accurate pain reporting and managing the pain via a tailored mix of pharmacological and non-pharmacological interventions will help minimise distress to the child.

Key Points to Remember

Use OPQRST or SOCRATES to assess pain. Use an age appropriate pain scale:

o 0-3 year FLACC / EVENDOLo 3-12 Wong-Baker FACES® or Oucher!TM

o 8+ NPRS/ARS/VAS Manage pain using both pharmacological and non-pharmacological interventions where

possible. Always document a pre and post intervention pain score. Remember to document non-pharmacological interventions used.

Conflicts

The author declares no conflicts of interest

Multiple Choice Questions

1. What are the potential consequences of not managing pain in children?a. Post-traumatic stress disorderb. Altered pain perceptionc. Long-term changes in stress hormone responsed. All of the above

2. Which pain assessment tool is most appropriate for a 2-year-old female with a burns injury?a. NPRSb. Wong-Bakerc. FLACC

3. Which pain assessment tool is most appropriate for a 13-year-old male with cognitive impairment?

a. NPRSb. Wong-Bakerc. FLACC

4. Which pain assessment tool is most appropriate for a 4-year-old male with abdominal pain?a. NPRSb. Wong-Bakerc. FLACC

5. Which is the least effective analgesic for pre-hospital injured children?a. Paracetamol tabletsb. Entonoxc. Oral Morphined. Morphine Sulphate IV

6. Why is accurate documentation important?a. Helps develop better patient care through more accurate clinical audit and researchb. Useful for personal reflections and CPD purposesc. Provides more detailed information for clinicians at handoverd. All of the above

7. When is a ‘clinically meaningful’ reduction in pain achieved? At a pain score reduction of:a. 1 or more out of 10b. 2 or more out of 10c. 3 or more out of 10d. 4 or more out of 10

8. Which is the most common cause of pain in children in the pre-hospital setting?a. Abdominal Painb. Chest Painc. Traumatic Injuryd. Headache

9. Why is it important to document a pre and post-intervention pain score?a. To accurately measure the effectiveness of pain managementb. To improve patient care and clinical handoverc. To improve the quality of any research that utilises your clinical recordd. All of the above

10. Which non-pharmacological interventions can you use to help manage pain in children?a. Distractionb. Splinting and bandagesc. Emotional support from parents / guardians / friendsd. All of the above

Answers:

1. D2. C3. C4. B5. A6. D7. B8. C9. D

10. D

References

AUSTRALIAN-GOVERNMENT. 2013. FLACC Pain Scale [Online]. Available: http://www.health.gov.au/internet/publications/publishing.nsf/Content/triageqrg~triageqrg-pain~triageqrg-FLACC [Accessed 19-Jan-2018].

BEYER, J. E., VILLARRUEL, A. M. & DENYES, M. J. 2009. Oucher [Online]. Available: http://www.oucher.org/index.html [Accessed 19-Jan-2018].

BOC. 2015. Entonox. The Essential Guide [Online]. Available: http://www.bochealthcare.co.uk/internet.lh.lh.gbr/en/images/entonox_essential_guide_hlc401955_Sep10409_64836.pdf [Accessed 19-Jan-2018].

BROWN, S. N., KUMAR, D., MILLINS, M. & MARK, J. 2016. UK Ambulance Services Clinical Practice Guidelines 2016, Bridgwater, Class Profesional Publishing.

BULLOCH, B. & TENENBEIN, M. 2002. Assessment of clinically significant changes in acute pain in children. Acad Emerg Med, 9, 199-202.

FARRAR, J. T., BERLIN, J. A. & STROM, B. L. 2003. Clinically important changes in acute pain outcome measures: a validation study. J Pain Symptom Manage, 25, 406-11.

FARRAR, J. T., YOUNG, J. P., JR., LAMOREAUX, L., WERTH, J. L. & POOLE, R. M. 2001. Clinical importance of changes in chronic pain intensity measured on an 11-point numerical pain rating scale. Pain, 94, 149-58.

FINLEY, G. A., FRANCK, L. S., GRUNAU, R. E. & VON BAEYER, C. L. 2005. Why Children's Pain Matters. International Association for the Study of Pain [Online], 13. Available: https://www.iasp-pain.org/PublicationsNews/NewsletterIssue.aspx?ItemNumber=2122.

FOURNIER-CHARRIERE, E., TOURNIAIRE, B., CARBAJAL, R., CIMERMAN, P., LASSAUGE, F., RICARD, C., REITER, F., TURQUIN, P., LOMBART, B., LETIERCE, A. & FALISSARD, B. 2012. EVENDOL, a new behavioral pain scale for children ages 0 to 7 years in the emergency department: design and validation. Pain, 153, 1573-82.

GOVERNMENT, V. S. 2013. Abdominal pain in children [Online]. Available: https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/abdominal-pain-in-children [Accessed 18-Jan-2018].

HALBSGUTH, U., RENTSCH, K. M., EICH-HOCHLI, D., DITERICH, I. & FATTINGER, K. 2008. Oral diacetylmorphine (heroin) yields greater morphine bioavailability than oral morphine: bioavailability related to dosage and prior opioid exposure. Br J Clin Pharmacol, 66, 781-91.

HEINRICH, M., MENZEL, C., HOFFMANN, F., BERGER, M. & SCHWEINITZ, D. 2015. Self-administered procedural analgesia using nitrous oxide/oxygen (50:50) in the pediatric surgery emergency room: effectiveness and limitations. Eur J Pediatr Surg, 25, 250-6.

HO, K., SPENCE, J. & MURPHY, M. F. 1996. Review of pain-measurement tools. Ann Emerg Med, 27, 427-32.

HOSKIN, P. J., HANKS, G. W., AHERNE, G. W., CHAPMAN, D., LITTLETON, P. & FILSHIE, J. 1989. The bioavailability and pharmacokinetics of morphine after intravenous, oral and buccal administration in healthy volunteers. Br J Clin Pharmacol, 27, 499-505.

IASP. 1994. IASP Taxonomy [Online]. Available: https://www.iasp-pain.org/Taxonomy?navItemNumber=576 [Accessed 05-Apr-2017].

LERNER, E. B., DAYAN, P. S., BROWN, K., FUCHS, S., LEONARD, J., BORGIALLI, D., BABCOCK, L., HOYLE, J. D., JR., KWOK, M., LILLIS, K., NIGROVIC, L. E., MAHAJAN, P., ROGERS, A., SCHWARTZ, H., SOPRANO, J., TSAROUHAS, N., TURNIPSEED, S., FUNAI, T. & FOLTIN, G. 2014. Characteristics

of the pediatric patients treated by the Pediatric Emergency Care Applied Research Network's affiliated EMS agencies. Prehosp Emerg Care, 18, 52-9.

LOHMAN, D., SCHLEIFER, R. & AMON, J. J. 2010. Access to pain treatment as a human right. BMC Med, 8, 8.

LORD, B. 2015. The Assessment of Pain in Paramedic Practice [Online]. Available: https://www.emsreference.com/articles/article/assessment-pain-paramedic-practice-0 [Accessed 18-Jan-2018].

MELZACK, R. & WALL, P. D. 1965. Pain Mechanisms: A New Theory. Science, 150, 971-978.MERKEL, S. I., VOEPEL-LEWIS, T., SHAYEVITZ, J. R. & MALVIYA, S. 1997. The FLACC: a behavioral scale

for scoring postoperative pain in young children. Pediatr Nurs, 23, 293-7.MURPHY, A., BARRETT, M., CRONIN, J., MCCOY, S., LARKIN, P., BRENNER, M., WAKAI, A. &

O'SULLIVAN, R. 2014. A qualitative study of the barriers to prehospital management of acute pain in children. Emerg Med J, 31, 493-8.

MYRVIK, M. P., BRANDOW, A. M., DRENDEL, A. L., YAN, K., HOFFMANN, R. G. & PANEPINTO, J. A. 2013. Clinically meaningful measurement of pain in children with sickle cell disease. Pediatr Blood Cancer, 60, 1689-95.

REIGART, J. R., CHAMBERLAIN, K. H., ELDRIDGE, D., O'BRIEN, E. S., FREELAND, K. D., LARSEN, P., GOFF, D. & HARTZOG, T. H. 2012. Peripheral intravenous access in pediatric inpatients. Clin Pediatr (Phila), 51, 468-72.

SAXE, G., STODDARD, F., COURTNEY, D., CUNNINGHAM, K., CHAWLA, N., SHERIDAN, R., KING, D. & KING, L. 2001. Relationship between acute morphine and the course of PTSD in children with burns. J Am Acad Child Adolesc Psychiatry, 40, 915-21.

SHERIDAN, R. L., STODDARD, F. J., KAZIS, L. E., LEE, A., LI, N. C., KAGAN, R. J., PALMIERI, T. L., MEYER, W. J., 3RD, NICOLAI, M., STUBBS, T. K., CHAN, G., HINSON, M. I., HERNDON, D. N. & TOMPKINS, R. G. 2014. Long-term posttraumatic stress symptoms vary inversely with early opiate dosing in children recovering from serious burns: effects durable at 4 years. J Trauma Acute Care Surg, 76, 828-32.

SOLOMON, P. 2001. Congruence between health professionals' and patients' pain ratings: a review of the literature. Scand J Caring Sci, 15, 174-80.

SROUJI, R., RATNAPALAN, S. & SCHNEEWEISS, S. 2010. Pain in children: assessment and nonpharmacological management. Int J Pediatr, 2010.

STEPHENSON, T. 2005. How children's responses to drugs differ from adults. Br J Clin Pharmacol, 59, 670-3.

VON BAEYER, C. L., SPAGRUD, L. J., MCCORMICK, J. C., CHOO, E., NEVILLE, K. & CONNELLY, M. A. 2009. Three new datasets supporting use of the Numerical Rating Scale (NRS-11) for children's self-reports of pain intensity. Pain, 143, 223-7.

WHITLEY, G. A. & BATH-HEXTALL, F. 2017. Does current analgesia effectively reduce pain in children caused by trauma, within a UK ambulance service. A service evaluation. British Paramedic Journal, 1, 21-28.

WHO. 1986. Cancer Pain Relief. Available: http://apps.who.int/iris/handle/10665/43944 [Accessed 21-Feb-2018].

WHO. 2012. WHO guidelines on the pharmacological treatment of persisting pain in children with medical illnesses. Available: http://apps.who.int/iris/bitstream/10665/44540/1/9789241548120_Guidelines.pdf [Accessed 21-02-2018].

WHO. 2015. 19th WHO Model List of Essential Medicines [Online]. Available: http://www.who.int/medicines/publications/essentialmedicines/EML2015_8-May-15.pdf [Accessed 05-Apr-2017].

WONG-BAKER. 2017. Wong-Baker FACES® Pain Rating Scale. Retrieved [01-Feb-2018] with permission from http://www.WongBakerFACES.org. [Online]. [Accessed 01-Feb-2018].