Ketamine 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

    • All Registered Nurses caring for patients receiving ketamine infusions should complete and pass their opioid competency annually. 

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    • Ketamine infusions are used for the management of moderate to severe pain.
    • Ketamine infusions may be used in conjunction with opioids, when using opioid infusions alone would result in inadequate analgesia or to minimise opioid tolerance when prolonged opioid administration is anticipated.
    • Ketamine infusions may be used alone in some situations.

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    Prescription of ketamine infusions

    • Ketamine infusion is a specialised analgesia technique and is managed by CPMS.
    • For patients (not already under the care of CPMS) with pain that may require a ketamine infusion, a referral needs to be made to CPMS by paging 5773 (24 hours) and completing an inpatient referral. The referrer needs to ensure that the patient's primary consultant has approved of CPMS involvement.
    • It is preferred that ONLY CPMS, Anaesthesia and ICU staff prescribe ketamine infusions.
    • The ketamine infusion is ordered/prescribed according to 3 weight-based tiers:
    Weight band Infusion preparation

    0-10 kg

    50 mg in 50 mL


    10-40 kg

    100 mg in 50 mL 


    40 kg + 
    (or fluid restricted)

    250 mg in 50 mL 


    • Dose range is 0 - 400 microgram/kg/hr. Usual starting dose is 100 - 200 microgram/kg/hr.
      Doses at the upper end of the dosing range may be required for severe pain such as in major trauma, burns and mucositis.

      Bolus dose of 100 – 200 mcg/kg (max 16 mg) can be administered every 30-60 minutes as needed for severe or escalating pain.

    • If ketamine has been prescribed by the Children’s Pain Management Service (CPMS) and the patient has required more than 3 boluses in a 2-hour period, contact CPMS to review the patient

      (see also Medication Guideline: Ketamine Infusion (


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    Ketamine infusion set up

    • The ketamine infusion must be prepared in accordance with RCH medication policy and the syringe labelled clearly with an intravenous additive label.
    • A syringe pump (eg B Braun Perfusor) must be used for all ketamine infusions. 
    • CPMS recommend the infusion pump and infusion line be clearly labelled with the blue IV analgesia labels as an additional safety feature.
    • The two authorised persons that make up each ketamine syringe must sign the ketamine infusion prescription. 
    • A 3-way-tap at the syringe end of the ketamine infusion line is not required. 
    • The syringe and lines should be changed every 72 hours or more often depending on individual unit policy or the patient's medical condition. 
    • Prescribed bolus doses of the ketamine infusion should ONLY be administered using the bolus feature on the syringe pump (which delivers boluses in increments of up to 2 mL). Guardrails should be set and checked.

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    Ketamine infusion delivery

    • If the infusion rate needs to be increased beyond 200 mcg/kg/hr, CPMS should be contacted.
    • If the patient requires more than 3 boluses in a two-hour period, CPMS should be contacted.
    • The volume infused should be checked every hour and documented on the fluid balance chart.

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    Concurrent drugs

    • Paracetamol, opioids, clonidine, local anaesthetics, tramadol and NSAIDs may be used concurrently with ketamine infusions and may help to improve analgesia and reduce side effects.
    • If opioid infusions are running in conjunction with a ketamine infusion, the opioid requirements may be reduced. The opioid infusion rate may need to be decreased to avoid over-sedation or respiratory depression.

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    • If the patient is receiving other medication that may cause sedation (for example, antihistamines, benzodiazepines, opioids or anticonvulsants), the child may be at increased risk of sedation and respiratory depression.
    • Some patient's receiving ketamine infusions experience dysphoria (hallucinations and/or vivid dreams). Patients, parents and staff should be made aware of this side effect. If dysphoria is problematic or distressing, the ketamine infusion rate may need to be reduced or the infusion ceased.

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    Patient review

    • CPMS reviews patients twice daily on week days and once daily on weekends and public holidays.
    • If the patient is experiencing pain or side-effects, CPMS must be called to review the patient.
    • CPMS can be contacted at all times on pager 5773.

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    The following observations should be recorded on the general observation chart
  • Sedation score, respiratory rate and heart rate: 1 hourly until the ketamine infusion is ceased.  
    [The need for less frequent observations for patients receiving long-term ketamine infusions should be discussed with CPMS.]
  • Pain score: 1 hourly while awake (using developmentally appropriate scale eg Wong-Baker Faces scale, Numeric scale or FLACC scale). 
  • Pulse oximetry: if indicated  
  • Indications for pulse oximetry:

    Pulse oximetry MUST BE implemented and used continuously in high-risk patients with:

    • University of Michigan Sedation Scale (UMSS)

       0 Awake and alert
       1 Minimally sedated: may appear tired/sleepy, responds to verbal conversation and/or sound 
       2 Moderately sedated: somnolent/sleeping, easily aroused with light tactile stimulation or simple verbal command
       3 Deep sedation: deep sleep, arousable only with deep or significant physical simulation
       4 Unarousable
       S Patient is sleeping
      UMSS sedation score > 2
    • Infants under 6 months of age
    • Significant cardiorespiratory impairment
    • Sleep apnoea, snoring or airway obstruction
    • Spot oximetry less than 94% SaO2

    or patients receiving:

    • Supplementary oxygen
    • Concurrent sedative agents

    Clinical indicators for 'spot' pulse oximetry are:

    • Tachypnoea or bradypnoea
    • Respiratory distress
    • Pallor or cyanosis or impaired oxygenation
    • Confusion or agitation
    • Hypotension
    • Nurse concern
    • The effectiveness of the analgesia should be recorded in the Nursing Progress notes.

    Observations following a bolus of ketamine infusion:

    • Respiratory rate and sedation score: every 5 minutes for 15 minutes and then return to routine observations. 
    • Pulse oximetry: if indicated
    • Pain assessment

    CPMS should be called if pain relief is inadequate after 3 boluses in two hours.

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

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    • CEASE the ketamine 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 saturations and administer oxygen
      via face mask at 8 L/min
    • Check circulation. If pulseless: commence chest compressions
    • Administer naloxone if opioid toxicity is suspected and the patient is receiving a concurrent opioid infusion or PCA
    • Call CPMS for urgent review

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    Ceasing the ketamine infusion

    • The decision to cease the ketamine infusion should be made in consultation with CPMS.
    • When ketamine is being used in conjunction with opioid infusions, the order in which the infusions are weaned should be discussed with CPMS.
    • Any remaining ketamine must be disposed of according to the RCH Drugs of Addiction policy.

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      First version written 2000, last Updated May 2024