Analgesia

Introduction

Analgesia is the relief of the perception of pain without sedation.

Pain is a more difficult concept to define precisely or to measure objectively. The International Association for the Study of Pain (IASP) defines pain as an unpleasant sensory and emotional experience, associated with actual or potential tissue damage, or described in terms of such damage. It is the significant emotional dimension that creates considerable variability in how a painful stimulus is experienced and thus how the interactions of physiological, psychological, developmental and situational factors can modify behaviour in both the short and long term.

Acute pain in children is one of the most common reasons for presentation to the emergency department (ED). In addition to the underlying injury or illness, subsequent medical procedures may also engender pain which is often associated with increased anxiety, avoidance behaviour, systemic symptoms and parental distress. Treating pain may not only relieve acute suffering but also decrease ongoing anxiety and negative memories, facilitate medical investigations and aid cooperation with other nonpainful procedures and treatments. The use of analgesia in procedural sedation is discussed in more detail in Chapter 3.2 .

Pain may be classified in a number of ways, for example, by severity, cause or pathophysiology. A simple classification is shown in Box 3.1.1 . Most commonly in the paediatric ED setting it is procedural and acute pain which need to be addressed.

Children with painful conditions can be difficult to assess, and their pain is often still underestimated and undertreated. Children often receive less analgesia than adults, and the administration of analgesia varies by age, with the youngest patients at the highest risk of receiving inadequate analgesia. ^,

Children’s pain can be misjudged because assessment requires tools that account for the wide range of children’s developmental stages. Pain is often undermedicated because of fears of oversedation, respiratory depression, addiction and unfamiliarity with use of sedative and analgesic agents in children.

ED staff should be proficient in the assessment and safe management of pain in children. Early and appropriate analgesia may be best achieved by using a systematic approach with well-developed pain management educational programmes, specific pain assessment and management policies and benchmarked standards for time-to-analgesia within the ED.

Assessment of pain

Assessment of pain should be individualised, continuous, measured and documented. Pain assessment and measurement tools have been developed that are suitable for children of different ages and developmental stages. Accurate assessment requires a detailed pain history and consideration of the complexity of the child’s pain perception and the influence of situational, psychological and developmental factors. Four useful means of recognising pain in children are outlined in Box 3.1.2 .

Because of its subjective nature, pain is best assessed using the child’s self-report. Observational assessment scoring may be useful when the child is too young or self-report is not possible, (e.g. children with cognitive impairment). Pain ratings provided by parents or regular carers may also be used. However, whilst there is good correlation between the child’s and the parent’s assessment of pain intensity, parents tend to underscore more severe pain being experienced by their children. The introduction of patient-held Pain Passports, which record regular self or parental pain assessments using some of the tools described below, have been shown to improve the assessment, provision and timeliness of analgesia. ^,

Physiological measures (e.g. heart rate and respiratory rate) may be useful in pain assessment in nonverbal or sedated children but may be confounded by stress reactions. For example, the child who is febrile or an infant who is hungry may give inappropriately high scores.

Specific pain assessment tools employing behavioural and vital sign observations have been developed for neonates (e.g. CRIES) and nonverbal (e.g. FLACC) or cognitively impaired children (e.g. r-FLACC, NCCPC-R or COMFORT tools). Pain scales for older children able to self-report, such as the Faces rating scale, which uses facial expressions depicting increasing pain or simple numerical or analogue scales, are commonly employed. Some of these age-dependent pain rating scales are outlined in Table 3.1.1 .

Table 3.1.1

Pain scoring

CRIES pain rating scale
The CRIES scale can be used in neonates and young infants up to a few months of age. It was originally designed for postoperative pain assessment; however, it can be employed for other procedures where baseline vital signs are known. Each of the 5 categories is scored from 0 to 2, and the scores are added to get a total score from 0 to 10.
	0	1	2
Crying	No	High pitched	Inconsolable
Requires O 2 for Sat >95%	No	<30% O 2	>30% O 2
Increased vital signs	HR & BP less than or equal to patient’s baseline (e.g. pre-op)	HR & BP increased by <20% of patient’s baseline	HR & BP increased by >20% of patient’s baseline
Expression	None	Grimace	Grimace/grunt
Sleepless	No	Wakes at frequent intervals	Constantly awake
FLACC scale
The FLACC scale is a behavioural scale for scoring pain in children between the ages of 2 months and 7 years or in persons unable to communicate. Each of the 5 categories is scored from 0 to 2, and the scores are added to get a total score from 0 to 10.
	0	1	2
Face	No particular expression or smile	Occasional grimace or frown, withdrawn, disinterested	Frequent to constant frown, clenched jaw, quivering chin
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 or sobs, frequent complaints
Consolability	Content, relaxed	Reassured by occasional touching, hugging or ‘talking to’, distractible	Difficult to console or comfort
The FLACC behavioural pain assessment scale © University of Michigan Health System can be reproduced for clinical or research use.
Faces rating scales (FRS)
These scales can be used with young children (as young as 4 years of age). They also work well for older children and adolescents, including those who speak a different language. Ask the patient to choose the face that best describes how they feel. The far left face indicates ‘no hurt’, and the far right face indicates ‘hurts worst’.
Numerical rating score (NRS)
This tool may be used for children over the age of 6–8 years. Instruct the patient to rate their pain intensity on a scale of 0 (‘no pain’) to 10 (‘the worst pain imaginable’).

BP, Blood pressure; HR, heart rate; Sat, saturation.

Management

Optimal analgesia is achieved by the combination of both nonpharmacological and pharmacological strategies with regular pain assessments. When using drugs there should also be careful consideration of the most appropriate route and dosage and close monitoring for adverse effects.

Pain management strategies should be individualised for the child’s level of pain and the anticipated discomfort of any procedure to be undertaken. Choice of agent will also depend on local resources, familiarity with doses, duration of action, adverse effects and contraindications.