Anesthesia for patients with opioid abuse and tolerance

From Anesthesiology News: http://www.anesthesiologynews.com/download/Opioid_AN0613_WM.pdf

Eval

-try to ask most use in a day, rather than average, more objective
-time of last dose, who is prescribing
-single questions alternative to CAGE-AID: How many times have you used illegal drugs in the past year?

Long term opioid therapy

Methadone
-opioid agonists, with some NMDA antagonism
-typically 30-40mg qd

Buprenorphine
-parital opioid agonist
-no high

Suboxone
-combo of buprenorphine and naloxone
-when injected, only naloxone works

Vivitrol
-extended release naltrexone
-opioid antagonist
-for etoh and opioid abuse
-monthly injection

I/O management

3 areas: manage intox, prevent/tx withdrawal, achieve effective analgesia

Antagonist reserved for life-threatening resp depression, as precipitating w/d can make management harder
If not receiving agonist therapy:
-take long-standing Rx as directed before surgery
-clonidine to tx withdrawal sx, 0.1mg bid, also tx specific sx as they arise

Multimodal pain relief
-iv tylenol, exparel
-ketamine, a2 agonists
-nsaids, regional
-pregalbin and gabapentin good for neuropathic pain

P/o

comfort and safety

opioid tolerant pts requires 2-3x more than naive patients
but still at risk from resp depression

Withdrawal happens 2/2 bolus nature of pain relief
combine long acting and pca for pain
make sure to restart methadone, divide into 3x/d dose to take advantage of analgesic properties

Post-op for Suboxone
-more complicated, buprenorphine has a celing effect (partial u agonist)
-so increasing dose intial helps, but tops out so side effects also top out, making it safer for long term management, but tought post-op
-Buprenorphine has 1000x affininty for u than morphine
–>longer half life, so persists on receptor
–>only partial agonist, so analgesia not complete
4 recs:
1. maintenance therapy continue, short-acting opioids titrate to effect
2. divide bupre into TID (if surgery not that invasive/painful)
3. d/c bupre and treat with full opioids, remember bupre can be present for up to 5 days after d/c. Be aware of withdrawal sx from bupre.
4. convert to methadone 30-40mg/day, must be written as rx for pain not withdrawal (illegal).

Post-Op for Naltrexone once monthly
-naltrex is competetive antagonist
-opioid admin is tough to predict
-depends if pt missed a dose, at end of dosing cycle etc.
-postpone elective surgery if possible until tx complete
-otherwise, multimodal with opioids

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