Clinical Case 043: Post-op pain puzzle
This case comes from Dr Jonathan Ramachenderan.
59 yo man presents with a small bowel obstruction likely secondary to adhesions. He has a background history of 4 previous laparotomies for recurrent bowel obstructions and Chronic Back pain with a spinal fusion 10 years previously.
He appears chronological older than his age and currently takes 100mg BD of Morphine Sulfate, Tramadol SR 150mg BD, Paracetamol SR 775mg TDS and Duloxetine 30mg. His renal and liver function is normal and he is intolerant of NSAID due to gastric irritation.
The procedure is long due to difficult division of adhesions and takes 5hours. He requires 30mg of Morphine intraoperatively and receives 100mg of Tramadol and 1gram of Paracetamol. Ketamine is considered but not given.
2 hours later he is in extreme pain, moaning, uncomfortable and unmanageable on the ward. You are called to assess and manage him.
There are multiple calls through the night as the patient’s analgesia isn’t adequate. He is uncomfortable and obviously distressed when you see him the next morning. He isn’t able to move in the bed and simply lifting his gown to examine him is painful. He has used 200mg of morphine in 16hours.
His opioid is rotated (morphine to fentanyl) and opioid requirement is revisited and an equivalency is calculated (200mg oral morphine = 1200mcg fentanyl/ 24hours). He is then given a background of 50mcg/hour with a 20mcg bolus.
Methadone is also started intravenously 10mg BD.
Ketamine is continued at 0.1mg/kg/hr.
His pain relief is instant following the TAP block on the ward. The opioid rotation helps to alleviate his pain and as his oral intake begins, he is re-started unto a lower oxycontin dose (75mg BD) with breakthrough oxycodone. His ketamine is first to come down as his pain remits and his fentanyl PCA is soon to follow. He is also commenced unto his regular tramadol with pregabalin 50mg TDS.
Great Case JR! We will run a second post discussing the theory and practicality of managing post op pain in chronic pain patients soon. Love to hear your feedback and pearls around this scenario. Thanks – Casey.
great case JR and talk about a multimodal analgesic cake approach!
firstly well done for getting on top of the post op pain in the end. can be very tricky in the chronic pain patient
I have to ask why the dose of ketamine infusion was so low? There are published series of palliative care patients being run on 20-40mg ketamine per hour for up to several weeks as a SC infusion…often in an outpatient or home setting. analgesic doses are cited often at 0.5mg/kg onwards.
Also reading the case, this patient was a sitting duck for opioid withdrawal given his chronic requirements, it seems a lot of the post op symptoms were related to that, right?
does that explain the use of methadone?
I’ve been using lots of norspan in recent years, to switch some of my chronic pain (the oxycontin/panadeine forte crowd) over to a patch formulation with less abuse potential
Works a treat
Until of course they get an acute problem and require opiates in hospital…
For this chap I’d have considered TAP blocks at the end of the case, plus a fentanyl/ketamine PCA post-op (how was he in recovery before hitting the ward?
Methadone’s also pretty useful – have you used the IV form at induction – seems to give good relief for up to 16hrs post op