Ezra N Teitelbaum, MD, Nathaniel J Soper, MD, Lubomyr Boris, BS, Frederic Nicodeme, MD, Peter J Kahrilas, MD, John E Pandolfino, MD, Eric S Hungness, MD. Northwestern University Feinberg School of Medicine.
INTRODUCTION: A novel measurement tool, the functional lumen imaging probe (FLIP), allows for assessment of changes in esophagogastric junction (EGJ) physiology in real-time during operations for achalasia. In this study, we evaluated which preoperative patient factors were associated with 1) baseline EGJ distensibility (i.e. compliance) and 2) increases in distensibility after surgical myotomy, as measured with intraoperative FLIP.
METHODS: Patients with achalasia were assessed preoperatively with a history including Eckardt symptom score, high-resolution manometry (HRM), timed barium esophagram (TBE) and upper endoscopy. Distensibility index (DI) (defined as the minimum cross-sectional area at the EGJ divided by pressure) was then measured intraoperatively with FLIP (distension volume of 40ml) in patients undergoing laparoscopic Heller myotomy (LHM) and peroral esophageal myotomy (POEM). After induction of anesthesia, paralysis and intubation, a baseline DI measurement was taken. After conclusion of the procedure (including deinsufflation of pneumoperitoneum during LHM), a final DI measurement was taken. Associations between preoperative patient characteristics and baseline DI were tested using a Pearson’s correlation. Associations between patient factors and change in DI (i.e. final DI minus baseline DI) were tested independently for LHM and POEM patients.
RESULTS: Intraoperative FLIP measurements were taken in 38 patients, 14 undergoing LHM and 24 undergoing POEM. Preoperative duration of symptoms and prior endoscopic treatment for achalasia were both positively associated with higher baseline DI (correlation coefficients r=.52 and r=.41 respectively, both p<.05). Eckardt score was negatively associated with baseline DI at a trend level (r= -.33, p=.09). On preoperative HRM, EGJ resting pressure was negatively associated with baseline DI (r= -.48, p<.01) but there was no association between EGJ relaxation pressure and baseline DI. Patients with type I achalasia had a higher baseline DI than those with type II or III (mean type I: 2.7 ±2 vs. type II: 1.1 ±.06 vs. type III: 1.1 ±0.5 mm2/mmHg, p<.05 for I vs. II and III). On TBE, contrast column height was negatively associated with baseline DI (r= -.53, p=.01). Both LHM and POEM resulted in a significant increase in DI, but the increase as a result of POEM was larger (LHM: 4.9 ±3.5 vs. POEM: 7.5 ±3.3 mm2/mmHg, p=.03). During POEM, preoperative duration of symptoms and prior treatment for achalasia were both positively associated with a larger increase in DI as a result of the procedure (r=.53 and r=.41, both p<.05). Patients with type I achalasia also had larger increases in DI as a result of POEM than those with type II (type I: 10 ±3.8 vs. type II: 6.3 ±2.7 mm2/mmHg, p<.01). For patients undergoing LHM, no preoperative factors were significantly associated with a larger change in DI.
CONCLUSIONS: Patients with longer symptom duration, prior endoscopic treatment, and type I achalasia had a higher baseline DI, whereas those with higher EGJ resting pressures had a lower baseline DI. POEM resulted in a larger increase in EGJ distensibility than LHM, and POEM may result in particularly large increases in DI for patients with long-standing and/or type I achalasia.