After Whipple, a 0.2 mg intrathecal injection matched a wound catheter — and beat it early

Design

Open-label randomised non-inferiority trial, margin 1.0

Population

92 adults undergoing elective open pancreatoduodenectomy at a tertiary centre, per-protocol

Primary outcome

Mean coughing pain score averaged over 24, 48 and 72 hours

Effect

5.7 ± 1.7 intrathecal morphine vs 6.1 ± 1.5 wound infiltration; difference −0.5 (95% CI −1.1 to 0.2)

Thoracic epidural analgesia remains the reference for open pancreatoduodenectomy in many units, but it fails, it is contraindicated often enough to matter, and it ties a patient to a catheter through the days when mobilisation is the point. Intrathecal morphine and continuous wound infiltration are the two usual alternatives, and they had not been compared directly.

Ninety-two patients were randomised to a single 0.2 mg intrathecal morphine injection or bilateral preperitoneal wound infiltration, both on top of standardised multimodal analgesia and intravenous patient-controlled analgesia. On the primary outcome — mean coughing pain averaged across 24, 48 and 72 hours — intrathecal morphine was non-inferior, with a mean difference of −0.5 (95% CI −1.1 to 0.2) against a non-inferiority margin of 1.0. It was better at two hours both at rest and on coughing, still better on coughing at 24 hours, and used less patient-controlled fentanyl.

The cost is early and specific: more respiratory depression and more pruritus within the first 24 hours. Neither is trivial after a Whipple, and both are manageable if anticipated. The honest reading is that a single injection given at induction does the work of a catheter system, provided the first postoperative day is monitored properly.

• 0.2 mg is the dose tested — higher intrathecal morphine doses shift the respiratory risk without evidence of extra benefit here
• Plan first-night monitoring explicitly: respiratory rate and sedation score, not just pain score
• Have an antipruritic pathway agreed in advance; pruritus is the complaint that drives requests to reverse the block
• Both arms kept patient-controlled analgesia, so this compares adjuncts, not stand-alone techniques
• In units without wound catheter systems or pumps, this removes the main argument for buying them for this operation

Why it matters

It makes the cheaper, simpler technique the defensible one, which matters most in units where a wound catheter system is a purchase rather than a habit.

Don't overread it

Single centre, open label, 92 patients in the per-protocol analysis. Non-inferiority on a pain score is not evidence of equivalent recovery, and the trial was not powered for complications.

The statistics, in plain English

Non-inferiority was declared because the upper bound of the confidence interval, 0.2, sits below the pre-specified margin of 1.0 — meaning intrathecal morphine is very unlikely to be worse by a clinically meaningful amount. Note what the absolute numbers say: mean coughing pain of 5.7 and 6.1 on a 10-point scale. Both techniques leave patients with substantial pain on coughing after a Whipple, so this is a comparison between two imperfect options rather than a demonstration that either is adequate.

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