Gradual withdrawal of remifentanil infusion may prevent opioid-induced hyperalgesia††This Article is accompanied by Editorial Aew050

The aim of this study was to examine if gradual withdrawal of remifentanil infusion prevented opioid-induced hyperalgesia (OIH) as opposed to abrupt withdrawal. OIH duration was also evaluated. Nineteen volunteers were enrolled in this randomized, double-blinded, placebo-controlled, crossover study. All went through three sessions: abrupt or gradual withdrawal of remifentanil infusion and placebo. Remifentanil was administered at 2.5 ng ml−1 for 30 min before abrupt withdrawal or gradual withdrawal by 0.6 ng ml−1 every five min. Pain was assessed at baseline, during infusion, 45–50 min and 105–110 min after end of infusions using the heat pain test (HPT) and the cold pressor test (CPT). The HPT 45 min after infusion indicated OIH development in the abrupt withdrawal session with higher pain scores compared with the gradual withdrawal and placebo sessions (both P