The perioperative combination of methadone and ketamine reduces post-operative opioid usage compared with methadone alone
Acta Anaesthesiologica Scandinavica,
Clinical Article
Pacreu S et al. – Perioperative ketamine–methadone (ME) combination significantly decreased opioid consumption by patient–controlled analgesia (PCA).
Methods- This was a randomised double–blind study.
- During sevoflurane–remifentanil anaesthesia, 11 patients in each group received the following: ketamine bolus (0.5mg/kg) after tracheal intubation, followed by an infusion of 2.5µg/kg/min in the MK or saline bolus plus infusion in the ME group.
- Post–operative analgesia–during 48h–was provided by patient–controlled analgesia (PCA), delivering bolus containing the following: ME 0.25mg plus ketamine 0.5mg in the MK group or ME 0.5mg in the ME group.
- Lockout was 10min, maximum of 3 boluses/h in both groups.
- Before closing the wound, all the patients received intravenous (i.v.) ME 0.1mg/kg, dexketoprophen and paracetamol.
- Pain intensity was evaluated by a numerical rating scale (NRS), on arrival at recovery room (RR) and 24 and 48h after surgery.
- In the RR, i.v. ME was administered until NRS was 3 when PCA was started.
- Dexketoprophen and paracetamol were administered 48h.
- Remifentanil requirements were higher in the MK group (P=0.004).
- Patients in the MK group received 70% less ME by PCA at 24h (MK vs. ME group, median and interquartile range)–3.43mg (1.9–6.5) vs. 15mg (9.65–17.38) (P<0.001)–and at 48h–2mg (0.5–3.63) vs. 9.5mg (3.5–13.75) (P=0.001).
- Patients in the MK group also attempted less doses, at 24h: 19.5 (12.75–79.5) vs. 98 (41.5–137) (P=0.043).
- Both groups had similar NRS values and comparable side effects.
