4.2 Chronic Opioid Use + Spinal Cord Stimulators Flashcards
Q2 — Opioids, spinal cord stimulators and
intrathecal pumps
a) How should you manage the perioperative opioid requirements of a patient who is having elective surgery and who takes regular opioids for non-malignant pain?
A multidisciplinary team approach is required comprising patient
education, planning for analgesia depending on the nature of surgery and implementing multimodal analgesia along with postoperative analgesic support — all key to optimising the outcomes:
1 ● Early recognition of these complex patients by
pre-assessment teams
and surgeons followed by appropriate
referrals to anaesthetists, pain
specialists, psychologists, etc.
2 ● Thorough patient assessment in
terms of patient expectations,
opioid doses and their side effects
and the ability to engage with services like
the pain team, physiotherapists, etc., as needed.
3 ● Maximising the use of opioid-sparing techniques in the perioperative period —
regular paracetamol, NSAIDs/COX2 inhibitors as
appropriate along with local anaesthetic techniques ranging from
local anaesthetic infiltration of the wound,
the use of wound catheters for infiltration,
regional anaesthesia or central neuraxial
blockade.
4 ● Other opioid-sparing medications like gabapentinoids, ketamine, clonidine and intravenous lignocaine infusions.
5 ● Recognition and prevention of opioid withdrawal by
continuing/replacing the preoperative opioids appropriately.
Use conversion tables/equianalgesic doses to convert parent opioid to an oral or IV morphine equivalent dose to achieve this.
6 ● Recognising that these patients are likely to need more opioids as compared with opioid-naïve patients and supplementing them with opioids in the form of
IV PCA or orally as appropriate.
7 ● Being mindful of opioid tolerance and opioid-induced hyperalgesia in this group of patients.
8 ● Provide education on tapering strong opioids to the intended dose after discharge.
b) Give the conversion factors for oral tramadol, codeine and
oxycodone to the equianalgesic oral morphine dose.
● 67mg oral tramadol = 10mg oral morphine.
● 100mg oral codeine = 10mg oral morphine.
● 5mg oral oxycodone = 10mg oral morphine.
c) What are the perioperative implications of an existing spinal
cord stimulator?
Patients may present for surgery with
an external (temporary) or internal (implanted)
spinal cord stimulator.
For general and regional anaesthesia:
● Neuraxial blockade may be administered if essential,
provided the site for the spinal/epidural needle
or epidural catheter is away from the
spinal cord stimulator implant and its wires.
Fluoroscopic guidance is advisable if possible.
● Confirm the position/location of the spinal cord stimulator
beforehand to know its location by operative records or radiological means.
● Electrocautery should be avoided if possible.
If unavoidable, use a bipolar cautery rather than unipolar.
● If monopolar diathermy is unavoidable, then make sure that its
earthing plate is kept as far away from the stimulator and its leads as possible.
● Consult with the device technician before and after surgery whenever possible.
● In peripheral nerve blocks,
use an ultrasound-guided approach
to localise the nerve rather than a
peripheral nerve stimulator as it can
interfere with the implant.
● The electrodes for defibrillation/cardioversion should be placed as much away from the leads and stimulator as possible. Use the lowest possible energy which is preferably done by a biphasic defibrillator.
d) What additional perioperative precautions should be taken if
the patient has an intrathecal drug delivery system fitted?
● Avoid spinal anaesthesia via a lumbar puncture route in the presence of intrathecal drug delivery (ITDD) systems.
● Avoid epidural anaesthesia at the level of the catheter insertion and connection.
It may be administered above or below the level where
the ITDD system is placed.
● Doses of IV opioids intraoperatively should be as for an opioid-naïve patient unless the patient is already on opioids via a route other than ITDD system opioids.
● ITDD pump malfunction is rare,
but this will need appropriate technical support.
● In the case of a baclofen intrathecal pump, sudden malfunction of the pump can cause baclofen withdrawal,
which is a medical emergency.
● Take appropriate precautions to
minimise infections of ITDD systems.
