SINGLE-BLINDED RANDOMIZED CONTROLLED TRIAL COMPARING THE EFFECT OF UNDERWATER VERSUS CARBON DIOXIDE INSUFFLATION...

"Underwater" endoscopic techniques have gained traction given its potential advantages. The aim of this multicenter randomized trial was to compare the effect of saline immersion (U-POEM) vs. carbon dioxide insufflation during peroral endoscopic myotomy (CO₂-POEM) on post-procedural pain.

Consecutive patients with achalasia subtype I and II were randomized in a 1:1 ratio to U-POEM or CO₂-POEM during the study period between February 2025 to November 2025. Pain was assessed using the validated numeric pain rating (NPRS) on a scale of 0 (none) to 10 (most severe). Primary outcome was immediate post-procedure pain. Secondary outcomes included: post-procedure pain at different time periods, requirement of analgesics, and clinical response (defined as a post-POEM Eckardt score <3).

Thirty-six patients were randomized to U-POEM (n=18) and CO₂-POEM (n=18). Technical and clinical success were 100% in both groups with no immediate and delayed adverse events. There were no differences in dissection speed or procedural time between the two groups. The immediate post-POEM mean NPRS score was significantly lower in the U-POEM vs. CO₂-POEM group (1.6 ± 1.6 vs. 3.3 ± 2.6; 95% CI: 0.23-3.16; p=0.02). When compared to CO₂-POEM, patients who underwent U-POEM reported less moderate-severe pain (16.7% vs. 55.5%; 95% CI: 0.04-0.64; p=0.04) and a lower number required opioids for post-operative pain management (5.5% vs. 50%; 95% CI: 0.11-0.68; p=0.007). Mean NPRS score remained lower in the U-POEM vs. CO₂-POEM group at 72-hours after the procedure (1.13±1.36 vs. 2.26±1.78; 95% CI: 0.06-2.20; p=0.04).

U-POEM was safe, effective, and associated with lower post-procedure pain scores when compared to CO2-POEM (U-POEM trial:NCT06918730).