Design: multicentre randomised controlled trial, conducted October 2020 to June 2023
Population: 244 children randomised during adolescent idiopathic scoliosis correction
Primary outcome: morphine consumption on postoperative day 1, adjusted for non-opioid analgesia
Effect: 0.4 vs 0.4 mg/kg, median difference -0.005 (95% CI -0.10 to 0.09), P = 0.93; intraoperative remifentanil 9.5 micrograms/kg lower with monitoring

A multicentre randomised trial enrolled 247 children having adolescent idiopathic scoliosis correction and randomised 244 to intraoperative remifentanil guided either by the Analgesia Nociception Index or by the usual haemodynamic parameters. The primary outcome was morphine consumption on day 1, adjusted for non-opioid analgesia; persistent postoperative pain at six months was secondary.

Day-1 morphine was identical: median 0.4 mg/kg in both arms, median difference -0.005 mg/kg (95% CI -0.10 to 0.09), P = 0.93. The monitor did change intraoperative practice - the guided group received 9.5 micrograms/kg less remifentanil (95% CI 4 to 15, P < 0.001). No secondary outcome differed, including persistent pain at six months.

This is a clean negative result on a device that is often justified by the hypothesis it just failed. Less intraoperative remifentanil is plausibly good in itself, given acute tolerance and hyperalgesia, but the trial looked for the downstream consequence and did not find one. Nociception monitoring in this population should not be bought or protocolised on the expectation of lower postoperative opioid requirement. If your unit already uses it, the honest framing is titration guidance, not outcome improvement.

Do not adopt nociception monitoring expecting lower postoperative opioid use
Treat reduced intraoperative remifentanil as a process measure, not a patient outcome
Keep the same postoperative analgesia plan regardless of intraoperative monitoring used
Monitor for persistent postoperative pain in scoliosis correction - it did not differ here, but it remains common
Judge new perioperative monitors on day-1 and longer-term outcomes, which is what this trial did

Why it matters

The device did what it claims to do intraoperatively and it made no difference to the patient afterwards.

The statistics, in plain English

A median difference of -0.005 mg/kg with an interval of -0.10 to 0.09 is as close to zero as a trial result gets, and the interval is narrow enough to exclude any difference that would matter clinically. That makes this a genuinely negative result rather than an underpowered one. The intraoperative remifentanil difference of 9.5 micrograms/kg was real and precise, which is exactly why the absence of a downstream effect is informative.