Download Intrathecal morphine

12
Sir Charles Gairdner Hospital
Acute Pain Service Guidelines
Intrathecal morphine
Single dose intrathecal morphine (eg in doses of 100 to 300 micrograms) can provide effective post
operative analgesia for up to 24 hours.
Intra operative use.
 Use preservative free morphine sulphate.
 Write dose and time administered on the Anaesthesia Record. To ensure that all non
theatre staff are aware of administration, complete a yellow Intrathecal Morphine
“sticker” and place it on the patients Drug chart and the Intravenous Opioid Analgesia
chart (if PCIA is in use).
 If large doses are given and/or the patient has significant co-morbidities, consider
arranging admission to a high dependency area for closer observation for the first 24
hours.
Side effects
Nausea and vomiting
PONV is common (approximately 30%) after intrathecal morphine (2). Order anti emetic as
per APS protocol.
Pruritus
Pruritus results from stimulation of spinal and supraspinal opioid receptors and may be
difficult to treat. (1) Order naloxone 100 micrograms SCI hourly prn.
Delayed respiratory depression
Respiratory depression which is late in onset, is a potentially dangerous complication as it
may occur unexpectedly hours after the injection of the opioid. It is believed to result from
the rostral spread of opioids in the CSF. It is more likely to occur with:
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Higher doses
Concomitant use of parenteral opioids
Elderly patients
Opioid naïve patients (2)
The timing of respiratory depression in opioid naive patients is 3.5 to 7.5 hours following
intrathecal injection. (1).
12
Sir Charles Gairdner Hospital
Acute Pain Service Guidelines
Monitoring should include hourly sedation score and respiratory rate for 24 hours post dose.
The patient should have oxygen administered (2L/min via nasal prongs or 5L/min via mask),
for 24 hours.
Urinary retention
Interaction with opioid receptors in the spinal cord causes detrusor muscle relaxation
leading to an increase in maximal bladder capacity and urinary retention. (2). This effect may
last for up to 16 hours. Insertion of an indwelling urinary catheter in theatre should be
considered for this fact alone.
If an indwelling catheter is not insitu, an initial bladder scan should be performed four hours
after return to the ward. If an IDC is not inserted, the scan should be repeated six hourly
until 16 hours post operatively.
1. Australian and New Zealand College of Anaesthetists. Acute pain management: scientific evidence.
Australian Government;2005. Available at www.anzca.edu.au.
2. Rawal N. Intraspinal opioids. In: Rowbotham DJ, Macintyre PE, editors. Clinical pain management:
acute pain. London, England. Arnold. 2003.
Date issued:
Date revised:
November 2005
Developed by:
Reviewed by:
Lyn Hellier, APS CNC
Drs L Roberts, J Graham.