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Anaesthesia and Pain Management

Opioid Infusion

  • This pain management guideline was written by the staff of the Children's Pain Management Service for the Royal Children's Hospital, Melbourne.

    This guideline may NOT be suitable for use in other institutions.

    Nurse competencies

    Indications

    • Opioid infusions are used for the management of moderate to severe pain when inadequate analgesia would result from oral analgesia or intermittent IV morphine boluses.
    • PCA may be more appropriate if the child is over 6 years of age, is cognitively able to understand the concept of PCA and is willing to self manage analgesia.

    Prescription of opioid infusions 

    NB: NICU & PICU use different concentrations and volumes for opioid infusions than those recommended for ward use

    • All prescribing and administration of opioid infusions should be in accordance with the RCH medication policy.
    • Any prescriber can order an opioid infusion according to the guidelines within the medication orders.
    • If the prescriber wishes the patient to be under the supervision of CPMS, a referral needs to be made by paging 5773 (24 hours) and completing a referral to CPMS. The referrer needs to ensure that the patient's primary consultant has approved of CPMS involvement.
    • The opioid infusion is in a 50 mL concentration for all children.
    • Morphine is the preferred opioid in most circumstances. Fentanyl or hydromorphone are alternative choices. 
    • The opioid infusion should be prescribed according to the opioid infusion guideline, including infusion rate, bolus size and frequency, reportable limits and naloxone order.

  • The naloxone prescriptions for pruritus, sedation and respiratory depression must be completed to enable prompt response when any opioid is prescribed

    • Naloxone

  • Pruritus / urinary retention - 1mcg/kg
  • Sedation - 2mcg/kg
  • Resuscitation - 10mcg/kg •Repeat after 1-2mins

  • Duration of action 45 mins (20-60mins)

    Morphine. 

    Add 0.5 mg/kg to a total of 50 mL diluent of choice (any IV maintenance solution of electrolytes and/or glucose) to make infusion.
    Infuse at 0-4 mL/hr: equivalent to 0-40 microgram/kg/hr
    Recommended initial bolus 5 mL (50 microgram/kg) of infusion
    Recommended bolus for pain or painful procedures: 1-2 mL (10-20 microgram/kg) of infusion at intervals of no less than 10 minutes.

    Fentanyl

    Add 15 microgram/kg  to a total volume of 50 mL diluent of choice (any IV maintenance solution of electrolytes and/or glucose) to make infusion. 
    Infuse at 0-4 mL: equivalent to 0-1.2 microgram/kg/hr.
    Recommended initial bolus: 2 mL ( 0.6 microgram/kg) of infusion.
    Recommended bolus for pain or painful procedures: 1 mL (0.3 microgram/kg ) of infusion at intervals of no less than 5 minutes.

    Hydromorphone

    Add 0.1mg/kg to a total volume of 50 mL diluent of choice (any IV maintenance solution of electrolytes and/or glucose) to make infusion. 
    Infuse at 0-4mL: equivalent to 0-8 micrograms/kg/hr
  • Recommended bolus for pain or painful procedures: 1-2 mL (2-4 microgram/kg) of infusion at intervals of no less than 10 minutes

  • Oxycodone

  • Add 0.5 mg/kg to a total of 50 mL diluent of choice (any IV maintenance solution of electrolytes and/or glucose) to make infusion.
    Infuse at 0-4 mL/hr: equivalent to 0-40 microgram/kg/hr
    Recommended initial bolus 5 mL (50 microgram/kg) of infusion
    Recommended bolus for pain or painful procedures: 1-2 mL (10-20 microgram/kg) of infusion at intervals of no less than 10 minutes.


  • Tramadol

    Add 4mg/kg to a total of 50 mL diluent of choice (any IV maintenance solution of electrolytes and/or glucose) to make infusion
  • Infuse at 0-4mL/hr: equivalent to 0-0.32mg/kg/hr

  • Recommend bolus for pain or painful procedures: 1-2mL (0.08-0.16 mg/kg) of infusion at intervals of no less than 10minutes


    Opioid infusion set up

    • The opioid infusion must be prepared in accordance with RCH medication policy and the syringe labelled clearly with a blue intravenous additives label. 
    • An infusion pump must be used for ALL opioid infusions and programmed using guardrails.
    • CPMS recommend the infusion pump and infusion line be clearly labelled with the blue IV opioid infusion labels as an additional safety feature. 
    • The two authorised persons who make up each opioid syringe must sign and verify the record of infusion
    • The syringe and lines should be changed every 72 hours or more often depending on individual unit policy or the patient's medical condition.
    • A 3-way-tap at the syringe end of the opioid infusion line is not necessary.
    • Bolus doses of opioid infusion (as prescribed on 'Opioid Infusion ') should ONLY be administered using the 'bolus button' on the syringe pump, which delivers the bolus in increments of up to 2 mL. If the syringe pump is in the 'ON' mode during the bolus, this will add the bolus volume to the total volume infused. The hands free mode is preferable for delivering a bolus.

    Opioid infusion delivery

    • Unless the patient has received a recent dose of opioid, a loading dose should be administered (according to the prescription) at the commencement of the infusion to ensure therapeutic plasma levels are quickly reached.
    • For rapid relief of pain (or anticipated pain), the prescribed bolus dose should be administered.
    • The infusion rate may be adjusted by the nurse within the dose range specified, according to the patient's level of pain.
    • It takes approximately four half-lives (~8hrs for morphine/hydromorphone, ~1.5hrs for fentanyl) for opioids to reach steady state plasma concentration if given as an infusion, therefore if the rate is to be increased, a bolus should be given as well.
    • Ideally the infusion rate should not be increased unless 3 boluses are required in a 1 hour period.
    • The volume infused should be checked every hour and documented on the fluid balance chart. Hourly rate will be verified on the medication chart.
    • The treatment of opioid overdose is the opioid antagonist naloxone. Naloxone is available in the ward/unit drug cupboard and on the ward/unit resuscitation trolley.
    • The naloxone dose is available in 3 dose ranges: 1 microgram/kg for opioid induced pruritus and urinary retention, 2 microgram/kg for excess sedation and 10 microgram/kg for resuscitation.

    Concurrent drugs

    • When opioid infusions are used, NO ORAL/ INTRAvenous opioids or sedative agents should be given without prior consultation with CPMS or an anaesthetist. 
    • Paracetamol, ketamine, local anaesthetics, tramadol and NSAIDs may be prescribed and administered concurrently with opioid infusions. They may help to reduce opioid requirements and associated side effects.

    Precautions

    • If the patient is receiving other medication that may cause sedation (e.g. antihistamines, benzodiazepines or anticonvulsants), the patient may be at increased risk of sedation and respiratory depression.
    • Prolonged administration of opioid infusions and impaired liver and/or renal function may alter drug elimination with ALL opioids and possibly result in drug accumulation and toxicity.
       
    • The morphine metabolite M3G causes CNS disturbances (including myoclonus and tremor) and the morphine metabolite M6G is a potent analgesic. Both these metabolites may accumulate in patients receiving long-term morphine infusions or patients with renal impairment.

    • The hydromorphone metabolite H3G may accumulate in patients receiving long-term hydromorphone infusions or patients with renal impairment. H3G can cause CNS disturbances (including confusion, tremor and agitation).
    • Prolonged fentanyl infusion may result in drug accumulation and potential increase in opioid related side effects.
    • Development of opioid tolerance with long-term administration of opioids may require the opioid dose to be increased.
    • Careful tapering of doses is important when weaning long-term opioids to avoid opioid withdrawal.

    Patient Review

    • Not all patients receiving opioid infusions are under the supervision of CPMS. If the primary treating team wishes the patient to be seen by CPMS, a referral needs to be made by one of the treating team by paging 5773 (24 hours) and completing an electronic inpatient referral. The referrer needs to ensure that the patient's primary consultant has approved of CPMS involvement.
    • CPMS reviews patients twice daily on week days and once daily on weekends and public holidays.
    • If analgesia is inadequate or the patient is experiencing side-effects, CPMS must be called to review the patient.
    • CPMS can be contacted at all times on pager 5773.

    Observations

    The following observations should be recorded on the Clinical Observation Chart :

    • Sedation score, respiratory rate and heart rate: 1 hourly until the opioid infusion is ceased
      [The need for less frequent observations for patients receiving long-term opioid infusions should be discussed with CPMS]
    •  Pain score: 1 hourly while awake (using developmentally appropriate scale eg Wong-Baker Faces scale, Numeric scale, FLACC scale or MPAT score) 
    • Vomiting score: 1 hourly for the first 12hrs, then 4 hourly as indicated
    • Pulse oximetry: if indicated
    • The effectiveness of the analgesia should be recorded in the Nursing Progress notes or in the appropriate clinical pathway. Pain assessment and score to be documented before and after analgesia intervention

    Observations following a bolus of opioid infusion:

    • Respiratory rate and sedation score: every 5 minutes for 15 minutes and then return to routine observations. 
    • Pulse oximetry: if indicated and for all infants under 6 months of age
    • Pain assessment

    CPMS should be called if pain relief is inadequate after more than 3 boluses in one hour.

    Any observations outside reportable limits (as identified on the clinical observation chart outside normal values for age) should be reported to CPMS +/- the primary treating team.

    COMPLICATIONS

    IF RESPIRATORY DEPRESSION OR OVERSEDATION IS SUSPECTED:

    • CEASE the opioid infusion
    • CEASE all other infusions that could be contributing to sedation
    • Attempt to rouse the patient
    • Call 22 22 [MET team] if appropriate
    • If apnoeic: administer bag & mask ventilation with 100% oxygen
    • If breathing: maintain airway, monitor oxygen saturation and administer oxygen
      via face mask at 8 L/min
    • Check circulation. If pulseless: commence chest compressions
    • Administer naloxone per instructions on the prescription if opioid toxicity is suspected
    • Call CPMS for urgent review

    Ceasing the opioid infusion

    • The decision to cease the opioid infusion should ideally be made in consultation with CPMS.
    • Oral opioids may be administered immediately after the opioid infusion is ceased.
    • The date and time of stopping the opioid infusion is recorded on the opioid infusion prescription and needs to be signed by the medical staff to discontinue.
    • Any remaining opioid infusion must be disposed of according to the RCH Drugs of Addiction policy.

    First version written June 1995, Updated Feb 2023