PAIN IN CHILDREN Are we accomplishing the optimal pain treatment?

Dr. Roshana Mallawaarachchi PAIN IN CHILDRENAre we accomplishing the optimal pain treatment?

A little History1970sonly half of children treated postoperatively with analgesics.

1980s only half of the doses of analgesics compared to adults with the same operation.

1990sdoing better with surgical but not medical pain and certainly not chronic pain.

Even NowUp to 40% of providers believe newborns dont experience pain.

A little HistoryText book of Paediatrics (1968): Swafford and Allan

Pediatric patients seldom need medication for the relief of pain. They tolerate discomfort well. The child will say he does not feel well or that he is uncomfortable or that he wants his parents but often will not relate this unhappiness to pain

A little HistoryWe no longer assume that neurological immaturity limits an infant or childs perception and experience of pain.

What is Pain?The International Association of the Study of Pain:

An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage

What is Pain?Pain is subjective. The response to pain is highly variable: Among different individuals.Same person at different times.Newborns, infants and disabled individuals can not describe their pain.But, from the gestational age of 20 weeks have a functional pain system.Anand and Craig extend the definition of Pain to include behavioral responses caused by pain.

What is Pain?1. Acute Pain: Due to nociception. (noci = Harm), Neural responses to traumatic or noxious stimuli.Somatic (Superficial / Deep)VisceralNociceptive pain is the commonest source of pain. in children. (Eg: Post Op pain)

2. Chronic Pain: May be due to nociception, major role: Psychological & Behavioral factors.

Nociceptive pain is caused by activation or sensitization of peripheral nociceptors.8

Acute pain

Sudden in onset Severe in natureIntensity can vary from mild to severeDifferent magnitudes Does not persist beyond 3 months.

The body's alarm systemChronic pain

Lasts for more than 3 months.A syndrome Acute pain can become chronic pain rapidly

Chronic pain serves no purpose

Development of Pain PathwaysAll neural pathways are present from birth. (including premature neonates)PNS: C-fibres are mature in neonates although their cortical connections at the level of the dorsal horn are immature.A-Beta fibres can produce nociceptive signaling from lower intensity stimuli. Less discrimination between the perception of noxious and non-noxious stimuli.

Development of Pain PathwaysInhibitory pathways are not fully developed in the spinal cord during early life.

More pain in Paediatric patients because: Widened receptive fields.Lower sensory discrimination .Reduced inhibitory pathways.

Pain Physiology

Pain StimuliPhysical Mechanical Thermal

Chemical Toxins, tissue proteasesHydrogen ions, Potassium ions, Prostaglandins, Histamine, Bradykinin and Serotonin

Tissue injury stimulate nociceptors. Tissue damage release prostaglandins

NociceptorsSpecial free nerve endings, at the end of sensory nerves.Located next to mast cells and small blood vessels.Found in the skin, muscles, joint capsules, visceral organs and arterial walls.

Two typesHigh Threshold MechanoceptorPolymodal Nociceptor

NociceptorsMechanoceptorRespond to intense mechanical stimulation. Polymodal nociceptors Respond to noxious mechanical, thermal and chemical stimuli.An initial pain stimulus stimulate nociceptors depolarise the sensory nerve Proportionate to the intensity of the stimulus The frequency of the stimuli

Pain PhysiologyWith stimuli mast cells activate.

Pain PhysiologyWith activation histamine is released

Pain PhysiologyHistamine stimulates nociceptor

Pain PhysiologyNociceptor release subs P & glutamate

Pain PhysiologyThat will stimulate mast cells further

Pain Physiology.. & release more histamine

Pain PhysiologyDepolarization of nociceptor occurs

Pain PhysiologyAction potentials transmitted along pain fiber

Pain PhysiologyTransmission of pain impulses to the spinal cord

The afferent or sensory neurones A delta () fibers C fibers The cell bodies are located in the dorsal root ganglions.Sensory nerve fibers enter the dorsal roots.Some afferents do enter the ventral roots.

Pain PhysiologyA & C fibers

The pain pathwayTransmits pain from the periphery to the cerebral cortex:

Consists of 3 neurones.

The primary or first order neurone BipolarCell body in the dorsal root ganglion The axon which projects to the dorsal horn of the spinal cord.

The pain pathwayA second order neurone: Synapses with the primary neurone in the dorsal horn.The axon crosses over and ascends.

There are two types of 2nd order neurones Wide -dynamic range (WDR) neurones -Respond to non-noxious stimuli and noxious stimuli

Nociceptive -specific (NS) neurones -Respond exclusively to noxious stimuli

The pain pathwayAscending tractsCarry pain information to the brain: Spinothalamic tract Spinoreticular tract Spinal mesencephalic tract Postsynaptic dorsal column pathway

The 3rd order neurone projects from the thalamus, reticular formation or mesencephalon to the cerebral cortex.

The pain pathwaySpinothalamic TractOriginate in laminae I and V. Cross over to the other side of the cord.Ascend in the anterolateral quadrant of the spinal cord. Reach thalamus Lateral nuclei and Medial nuclei. In the thalamus synapse with 3rd order neurones, 3rd order neurone project to Frontal cortex Somatosensory cortex

The pain pathwaySpinoreticular TractFibres of the spinoreticular tract ascend from the dorsal horn to the reticular formation in the brain stem.

The reticular formation plays a crucial role in processing pain information.

Activity in the spinothalamic and spinoreticular tracts are responsible for determining the quality and intensity of the pain.

The pain pathwayThe brain structuresThalamus The reticular formationThe limbic systemPeriaqueductal gray in the brain stemLentiform nucleus in the basal gangliaParts of the cerebral cortex The anterior cingulate cortexInsula Somatosensory cortex

The pain pathwayThalamus and hypothalamusA lot of pain information is relayed through the thalamus (spinothalamic tract) Fibers from the thalamus project toBrain stem- Sensory, arousal and autonomic components Sensory cortex and the frontal lobes- Behavioural or affective component

The pain pathwayLimbic systemIs a collection of components. It is sometimes called the emotional brain. Receives many fibers from the thalamus. Responsible for emotional aspects of pain and its responses (anxiety and fear) The amygdalaImportant for affective, emotional, behavioral and autonomic responses to pain.

The pain pathwayCerebral cortexAnterior Cingulate Cortex

Integrate information about pain perception. Involved in the perception of suffering and emotional response. Opioid receptors are abundant in this area.May be influential in modulating the pain experience.

The pain pathwaySomatosensory cortexLocated in the parietal lobes

Responsible for the conscious perception of pain Location Quality of the pain Magnitude of the stimulus

Knowing-doing gapReluctance of using new knowledge in real practice.

Due to: Lack of interestFear of using strong analgesicsMisconceptions

Why Analgesics?Untreated pain may have long-term negative effects on

Pain sensitivityImmune functioningNeurophysiologyAttitudesHealth care behaviour

Pain assessmentPain is a complex experience: So assessment scores have to be judged together with other clinical factorsBehavioral observationPhysical examOrigin of pain

Tools are based on Self-report - gold standard , Preferred methodObservation of behaviour

Pain assessmentSelf-report tools

Visual analogue scale (VAS) Wong-Baker Faces Pain Rating ScaleFaces Pain Scale - RevisedPoker chip tool

Self-report is the only truly direct measure of pain41

Pain assessmentVisual analogue scale (VAS) For ages 3- adultHorizontal line with no pain at one end to worst possible pain at the other.

Pain assessmentWong-Baker Faces Pain Rating ScaleFor acute pain. Age group 3-18 years.Six line-drawn faces range from no pain to worst pain.

Pain assessmentFaces Pain Scale-RevisedFor acute pain. Age group 4- 16 years.Six cartoon faces range from neutral to high pain expression.

Pain assessmentPoker chip toolChild chooses which chips represent the pain.One chip indicating a little hurt and all four chips indicating the most hurt.

How many pieces of hurt do you have right now?

Pain assessmentObservational Tools

FLACC Pain Assessment Tool Procedure Behavior ChecklistChildren's Hospital of Eastern Ontario Pain ScaleCOMFORT ScalePremature Infant Pain Profile

Pain assessmentFLACC Pain Assessment Tool A simple framework for quantifying pain; who may not be able to verbalize.5 categories of pain behaviours.Facial expressionLeg movementActivityCryConsolabilityTotal possible range of 0 to 10.

48

Pain assessmentProcedure Behavior ChecklistAge group 3-18 years.8 behaviours rated on occurrence and intensity.Muscle tensionScreamingCryingRestraint usedPain verbalizedAnxiety verbalizedVerbal stalling Physical resistance

Pain assessmentChildren's Hospital of Eastern Ontario Pain ScaleAge group 112 years. Assesses 6 behaviours. CryFacialChild verbalTorsoTouch Legs

Pain assessmentCOMFORT ScaleAge group 018 years.8 domains.AlertnessCalmness/agitationRespiratory responsePhysical movementMean arterial blood pressureHeart rateMuscle tone Facial tension

52

Pain assessmentPremature Infant Pain Profile7 indicators of pain.

Physiological Heart rate, Oxygen saturation

Behavioural dimensionsFacial expression, eye squeeze, brow bulge, nasolabial furrow, and crying

Pain assessmentRecommended measures for procedural and postoperative pain assessment:

Newborn3 yrCOMFORT or FLACC4 yr old FPS-R + COMFORT or FLACC57 yr old FPS-R7 yr old + VAS or NRS or FPS-R

Numeric Rating Scale54

Aetilogy of Paediatric PainMain causes of Acute pain in children:ProceduresSurgeryTrauma Acute medical illness

Successful pain management in Children:Education of staffPain assessmentAnticipation of painProvision of a calm environment Inclusion of parents

Procedure related painMultiple procedures are frequently required.

Aim:Minimize painMinimize physical discomfort Minimize psychological distress

Pharmacological and non-pharmacological methods.

uncontrolled pain at the time of the first procedure can adversely affect the level of pain and distress experienced on subsequent occasions.56

Procedure related painNon-pharmacological strategies:

Both child and parent should be adequately prepared.Gaining parents confidence.Age and developmentally appropriate information.Chance to ask any questions.Younger children: act out the procedure with a toy medical kit.Comfortable, calm and friendly environment.Equipment for distraction should be available.(Eg: Toys, interactive books, puppets, bubbles and electronic games)

procedure is planned and how this will be conducted. 57

Procedure related painPharmacological methodsAnalgesia with or without sedation.Topical anaesthesiaLocal infiltrationPeripheral nerve blockadeBiers blockNitrous oxideKetamine Intra-nasal fentanylMidazolam? : No analgesic effect / creates amnesia, increased excitation for each procedure.

Procedure related painCombination of Analgesics:LA, PCM, COX inhibitor Buffered anaesthetic solutions in wounds and infiltration.

Short acting drugs are preferred. Alfentanyl/FentanylAlpha 2 agonists (Clonidine/Dexmedetomidine)

Atomizing devices: Smaller dose, fast onset Eg: intranasal fentanyl, Sufentanyl, Dexmedetomidine

(Lignocaine and Mepivacaine without precipitation.Alpha 2: less respiratory depression when compare with opioids.

59

Procedural pain in the neonate:Blood Sampling: Sucrose or other sweet solutions can be usedTopical local anesthetics

Nonpharmacological measures Tactile stimulationBreast-feedingMassage of the heel

Procedural pain in the neonate:Lumbar punctureTopical local anesthesiaUrine samplingLocal anesthetic gelNasogastric tube placementSucrose can reduce the pain responseImmunization and intramuscular injectionSwaddling, breast-feeding or pacifier, and sucrose, least painful first, 25-gauge needle.IM should be avoided.

Procedural pain in older childrenChest drain (tube) insertion and removalGeneral anesthesia or sedation combined with SC infiltration of buffered lidocaine.

Change of dressings in children with burnsPotent opioid analgesia given by oral, transmucosal, or nasal routes.50% nitrous oxide/oxygen.

Procedural pain in older childrenIV cannulation:Topical LA (EMLA or AMETOP)Buffered injected LA (lidocaine + bicarbonate 10:1) with a fine 30G needle SC prior to cannulation.Nitrous oxide (5070%) inhalation.Vapocoolant topical spray. (ethyl chloride)Laceration repairTissue adhesivesHair apposition technique (HAT) in scalp lacerationsTopical anesthetic preparations (LAT)

Faster onset with buffered solutions.LAT (lidocaineadrenalinetetracaine)64

Post-operative painDiscuss pre-operatively with the carers and with the children.Aim: Control pain as early as possible.

Regional anaesthetic techniques before starting surgery, multi-modal analgesia are preferred. Alpha-2-agonists as premedication: Limits post anaesthesia agitation.Major surgeries: Low dose S-Ketamine continuous infusions for several days.Dosages and the interval should be adjusted based on the assessment.

Agitation: a troublesome for the patient, parents and staff.65

ENT surgeryMyringotomy: Oral paracetamol or NSAIDSTonsillectomy: Intraoperative opioids, dexamethasone, and mild analgesics (NSAIDS and /or paracetamol)Mastoid and middle ear surgeryGreat auricular nerve block

Myringotomy is usually considered to be a minor procedure,,Tonsillectomy (adenoidectomy) is one of the mostfrequently performed procedures in children.Dexamethasone reduces PONV and postoperativepain scores66

OpthalmologyStrabismus surgeryIntraoperative LA blocks (subtenons or peribulbar)

Vitreoretinal surgeryNSAID, Peribulbar block

sub-Tenons space67

Dental proceduresNSAIDS with or without paracetamol.Swabs soaked with bupivacaine on exposed tooth sockets.

General surgery and urologySub-umbilical surgeryWound infiltration, TAP block, ilio-inguinal nerve block and caudal analgesiaCircumcisionCaudal epidural and dorsal nerve blockTopical applicationHypospadias repairCaudal or dorsal nerve blockOpen inguinal hernia repair LA wound infiltration, ilio-inguinal nerve block, paravertebral block or caudal analgesia

Circumcision significantpostoperative pain and distress69

Major intra-abdominal surgery:Intravenous opioids either as continuous infusion, NCA, or PCA, Epidural analgesiaAppendicectomy:PCA combined with NSAIDLaparoscopic surgery:Infiltration of port sites with LA is part of a multimodal analgesic.Orthopaedics, spinal and plastic surgeryEpidural analgesia using opioidsShort-term NSAID

Trauma

Morphine is still the most commonly used first line analgesic for severe pain.Incrementally up to a dose of 0.1mg/kg.

Other methods:Topical anaesthesia, inhaled 50% N20/ 50% 02, IV regional anesthesia and inhalational or transmucosal opioids.

Pharmacological TherapiesParacetamolCOX InhibitorsOpioidsAlpha 2 agonistsS- KetamineLocal anaesthetics and Nerve blockOther Analgesics

Paracetamol (Acetaminophen)Should be considered at all stages.Inhibition of prostaglandin H2 and cyclo oxygenase 3 (COX-3) in CNS.Both anti-pyretic as well as analgesic action.Opioid sparing effect.Side effects and adverse reactions are uncommon.Complications: HepatotoxicityVariety of routes: Oral, Rectal, IV

Paracetamol (Acetaminophen)Oral dose: 15 20 mg/kg given 4-6 hourly for pain relief and anti-pyresis.

Rectal dose: 30-40 mg/kg or 20mg/kg for neonates.

IV: Greater dosing accuracy, rapid and predictable onset of action (within 5 min), Better until GI motility regain, Less toxicity, Reduce morphine dosage upto 50%.

Daily maximum dose is 90 mg/kg in children aged > 3 months. 60mg/kg: 3252 weeks PCA

rectal paracetamol is generally larger due to its unpredictable bioavailability;74

COX InhibitorsInhibits the cyclooxygenase-2 isoenzyme.Prevents the conversion of arachidonic acid to prostaglandins and thromboxane.Prostaglandins sensitize nociceptors to increase afferent nociceptive signalling.Considered as part of routine acute analgesic as opioid sparing effects.NSAID and paracetamol is recommended.Eg: diclofenac, ibuprofen and ketoprofen.

NSAID and paracetamol is recommended as there action is synergistic to providehigher quality analgesia and decrease opioid requirements.75

COX InhibitorsIbuprofen- oral suspension, infant drops, tablet and IV formulations.In children weighing > 7 kgLicensed from age: 3 monthsDose is 30mg/kg in 3-4 divided doses.

Diclofenac- tablets, suppository and parenteral formulations.Licensed from age: 6 monthsDose orally and per rectum is 0.31 mg/kg (max. 50 mg) 3 times daily.

COX InhibitorsKetorolac IM, IV or orallyNot licensed for use in children below 16 years of age.Only for the short term management.Higher risk of bleeding.

If post Op bleeding must be avoided (Neurosurgery) more selective COX 2 inhibitors are recommended. (Eg: Parecoxib)

COX InhibitorsSide effects:Hypersensitivity reactions.Reduce platelet aggregation and prolong BT.CI in coagulation disorders.Inhibit prostaglandin-mediated renal function.Gastric irritation and bleeding.Excess leukotriene > exacerbate Asthma (1:1000)

2% of asthmatic children are susceptible to aspirin-inducedbronchospasm and 5% of this subgroup78

COX InhibitorsA standard Multimodal analgesic approach important for fast recovery: Eg of a combination (Sweeden):

IV ParacetamolCOX inhibitorsAlpha 2 agonistsContinuous opioid infusion

OpioidsAct through dedicated receptors:Mu, Kappa, Delta and ORL-1 (orphanin like receptor)CNS and at sites of peripheral inflammation. Dose adjusted to age, clinical response and presence of side effects.What is Opioid rotation?Alteration of opioids to achieve less side effect and better analgesiaA combination of 2 opioids can be advantageous. Eg: low dose of Methadone

change in opioid drug or route of administration80

OpioidsCodeine should No longer used in children. (2012)Case reports of deaths in children with OSA undergone tonsilectomy.

OpioidsMorphine- Phenanthrene derivative.2 main metabolites: M-3-G, M-6-G.M-3-G : No analgesic effect / create excitationM-6-G: Active/ Analgesic effectInfants formation of M-3-G is more, causing: Jitteriness, sleep disturbances, signs of discomfort.

OpioidsMorphine- contOral, IV, IM, SC, rectal, intrathecal, epidural and intranasal.Guided by the age, weight and clinical response of the child.16 mn initially: 50150 micrograms/kg every 4 hrs6mn12 yrs 100-300 micrograms/kg every 4 hrs1218 yrs 520 mg every 4 hrs

OpioidsFentanyl-Synthetic phenylpyperidine derivative.100 times more potent than morphine.Inactive metabolites.IV, transmucosal, transdermal, inhalational or intra-nasal route.Procedure related pain.IV dose: titrate 0.51.0 mcg/kg (decrease in neonates)

OpioidsRemifentanilSynthetic phenylpyperidine derivative.IV infusions.Rapidly broken down by non-specific plasma and tissue esterases.Short elimination half-life (3-10 minutes).Induces hyperalgesic effect post operatively.Loading dose of 0.1 1 mcg/kg over 30 sec Infusion between 0.1 2mcg/kg/h.

OpioidsTramadolCentrally acting.Structurally related to morphine.It is not licensed for children under 12 years. Orally 50100 mg every 4 hoursMight be considered in neuropathic pain.

Patient Controlled Analgesia (PCA)Can be used in children as young as 5 years.Similar efficacy to opioid infusions.Morphine is most commonly used in PCAsBolus dose of 20mcg/kgBackground infusions of 4 mcg/kg/hr to maximise analgesia and minimise side-effects.Nurse controlled analgesia is also an accepted and effective variation in practice.

Alpha-2 AgonistsEg: Clonidine, DexmedetomidineCan be used in both nociceptive and neuropathic pain.Sedative, anxiolytic, and analgesic properties. Beneficial in Abdominal and ischaemic pain.No respiratory depression.Limited effect in GI motility. Less Nausea and constipation.Pain sensitization is reduced.12 mcg/kg clonidine to caudal prolongs analgesia

Alpha-2 AgonistsDose dependent sedation. Meta analysis confirmed benefits of using compared to midazolam as premedication. Lower incidence of postop agitation.

Adjuvants to Local anaesthetics in PNB and epidurals. (Eg: Levobupivacaine and Clonidine)

Recommend for post operative pain after discharge.

Should not be given to children with AV block Type II, III. (Reduce sympathetic outflow)

KetamineNMDA antagonist.Blocks peripheral nociception and prevents central sensitization.Procedural sedation.Animal models: Developing brain demonstrated neuroapoptosis.Dose is 1-2mg/kg IV and 4-13mg/kg IMLasting for 510 min.Low dose infusions can be used for several days post op.Adverse effects: laryngospasm, vomiting, salivation, increased muscle tone, emergence hallucinations, drowsiness, rashes and injection-site reactions.S-isomer has approximately 2X the analgesic potency.

Nitrous oxide50 % with oxygen for sedation and analgesia.Side effects: nausea, vomiting and dizziness. Prolonged periods may result in megaloblastic anaemia.

SucroseReduce many physiological and behavioral indicators of stress and pain in neonates.Related to the sweet taste.24% solution 12 min before a painful stimulus.Carefully to the tongue one drop at a time

Local anaesthetics and Nerve blocksBlock should be given before the surgical procedure.Safe in all ages.In conscious children pain on injection is due to acid solution; Buffered solution minimize the pain and faster onset.

BupivacaineAmide LA, racemic mixture.0.0625%0.75%Slow onset and a long duration.Carbonated solution: faster onsetComplete sensory blockade.Motor blockade depends.0.0625%-0.125% less0.25% incomplete motor block0.5% extensive motor block0.75% muscle relaxation Neonates: reduced hepatic clearance > accumulationLevobupivacaine: S-enantiomer, Less toxicity

very low incidence of motor blockincreased risk of myocardialdepression in overdose and when bupivacaineand antiarrhythmics are given together94

Suggested maximum dosages of bupivacaine, levobupivacaine and ropivacaine:Single bolus injection (mg/kg)

Neonates 2 Children 2.5?

Continuous infusion mg/kg/hr

Neonates 0.2Children 0.4

*A Guideline from the Association of Paediatric Anaesthetists of Great Britain and Ireland 2012

LidocaineAmide LA.Rapid onset of action. intermediate duration.Vasoconstrictor reduces systemic absorption, increases both the speed of onset and duration.Max dose 3 mg/kg.Max Epinephrine should be 5 microgm/kg

EMLALidocaine forms a mixture with prilocaine.Melting point lower than that of either ingredient.lidocaine 2.5% and prilocaine 2.5%.Venepuncture, intravenous or arterial cannulation, lumbar puncture, minor dermatological procedures.Applied at least 60 min and a max of 5 h.Should not be used on wounds or mucous membranes or for atopic dermatitis, near eyes.

corneal irritation97

Ametop4% Tetracaine gel.Rapid and prolonged surface anesthesia.Duration for 46 h

LET4% lidocaine, 0.1% epinephrine, and 0.5% tetracaineCombined in a gel.Direct Surface anesthetic to lacerations. (