Intraoperative FLIP — POEM, Fundoplication & Sleeve

Intraoperative FLIP turns a binary decision ("good enough?") into a numerical one. During POEM, baseline EGJ-DI is typically ≤ 1.5 mm²/mmHg; after a full submucosal myotomy you want a DI between 6 and 9 — under-cut leaves residual obstruction, over-cut risks long-term reflux. During laparoscopic Nissen, the surgical target is a DI of 2.0–3.5: tight enough to control reflux, loose enough to prevent dysphagia. In Heller with Dor, the sweet spot is 5–8. Each of these targets has been validated in prospective trials, and using them in real time reduces re-operation and persistent dysphagia rates.

The DeMeester and Northwestern groups have led much of this work. Su 2020 reported on 240 antireflux operations: targeting DI 2.0–3.5 dropped 1-year dysphagia from 14% to 4% and reflux recurrence remained < 8%. Holmstrom 2021 showed that POEM cases guided by intraoperative FLIP had a 92% clinical success rate at 1 year versus 78% in unguided cases.

A standard POEM myotomy is 6–8 cm long: 2 cm distal to the EGJ + 4–6 cm proximal. The intraoperative FLIP allows you to titrate the proximal extent and confirm completeness. Take a baseline measurement after the submucosal tunnel is created but before the myotomy. After the initial muscular cut, measure again. If DI < 6, extend the myotomy 1–2 cm proximally and re-measure. If DI 6–9, stop. If DI > 9 — a less common scenario — consider whether you have inadvertently extended into the cardia and consider adding a partial fundoplication via the same or a second-stage operation.

In type III achalasia and spastic disorders, the myotomy is intentionally longer (8–14 cm) to address the spastic body — FLIP topography (RRCs persisting after cut) is a stronger guide than DI alone for these phenotypes.

In laparoscopic Nissen, place a 56F bougie, create the fundic wrap over the bougie, and tie loose enough to fit one finger easily. Then measure DI with FLIP at standardised pneumoperitoneum (12–15 mmHg). If DI < 2.0, the wrap is too tight — release the most distal suture and re-measure. If DI > 3.5, the wrap is too loose — add a reinforcing suture. The 2.0–3.5 window holds across body habitus and is robust to the patient's pre-existing motility.

For Toupet (270° posterior) and Dor (180° anterior), the targets shift upwards (DI 3.0–4.0 and 4.0–5.0 respectively) because the partial wraps create less mechanical resistance. Always document which wrap configuration you used.

Post-sleeve reflux affects up to a third of patients. A tight incisural stenosis on FLIP (DI < 5 mm²/mmHg at the angularis) predicts both reflux and stasis. Some bariatric centres now run a FLIP probe along the new sleeve before closure — a tight zone prompts immediate intraoperative revision (re-stapling or seromyotomy) rather than a re-operation 6 months later.

A 2023 prospective cohort (Yu Surg Obes Relat Dis) measured FLIP-DI at three positions along the sleeve in 156 patients and found that an incisural DI < 4.0 carried a 6-fold relative risk of de-novo GERD at 1 year. Routine intraoperative FLIP is now being incorporated into best-practice algorithms at high-volume bariatric centres.

A typical intraoperative FLIP setup: (1) The EF-322N catheter is passed orally before patient positioning and parked in the stomach. (2) After laparoscopy starts, the surgeon and anaesthetist confirm pneumoperitoneum is stable at 12 mmHg. (3) The endoscopist or scrub nurse advances the balloon to the EGJ under direct view from the laparoscope and inflates to 30 mL → 40 mL → 50 mL → 60 mL. (4) The FLIP console is placed in the surgeon's line of sight on the boom monitor. (5) Measurements are repeated after each surgical step (myotomy, wrap, sleeve closure) and recorded on the operative note. The whole FLIP workflow adds 8–12 minutes to the case.