title: The Per Oral Endoscopic Myotomy (POEM) technique: how many preclinical procedures are needed to master it?
abstract: OBJECTIVE
  Per oral endoscopic myotomy (POEM) is a complex technique used in achalasia. Preclinical training is essential but little is known about the number of procedures needed. The aim of this study was to determine the number of procedures required to master POEM in an animal model.
  
  
  METHODS
  This prospective comparative study was conducted in two swine models at a single institution in Mexico City between November 2012 and October 2014: Group 1 (G1) = 30 ex vivo and Group 2 (G2) = 20 live swine models. POEM was mastered after finishing the five steps without complications. Time, characteristics, and complications were recorded. Velocity of tunnelization and myotomy (VTM) was determined. Ex vivo analysis was done in G1 immediately after finishing POEM and at day 30 in G2.
  
  
  RESULTS
  A total of 50 POEM were done in both groups (G1 = 30, G2 = 20). The mean times were 90.17 min (G1) and 89.50 min (G2) (P = 0.92). Myotomy was faster in G2 (21.10 vs 27.97 min; P = 0.009) with a slightly slower tunnelization (40.35 vs 41.13 min; P = 0.86). Myotomy was longer in G2 (9.25 vs 8.83 cm; P = 0.26). VTM between the groups was similar (G1 = 0.159 vs G2 = 0.157 cm/min; P = 0.925). Complications were: mucosotomy (G1 = 18 %, G2 = 8 %; P = 0.430), mediastinal perforation (G1 = 12 %, G2 = 8 %; P = 1.0), and perforation at the gastroesophageal junction (GEJ) level (G1 = 16 %, G2 = 4 %; P = 0.149). Seven models in G2 presented minor bleeding and there was one death not attributed to the procedure. Mastery was obtained after 26 cases.
  
  
  CONCLUSIONS
  We suggest that centers interested in learning POEM consider 26 procedures in animal models to master it before performing it in patients with achalasia.
authors.affiliation: Department of Endoscopy, Specialties Hospital, National Medical Center Century XXI, Mexico City, Mexico.
authors.forename: Oscar Víctor
authors.initials: OV
authors.lastname: Hernández Mondragón
authors.affiliation: Department of Anesthesiology and Biostatistics, Specialties Hospital, National Medical Center Century XXI, Mexico City, Mexico.
authors.forename: Dulce Maria
authors.initials: DM
authors.lastname: Rascón Martínez
authors.affiliation: Department of Veterinarian Surgery, Specialties Hospital, National Medical Center Century XXI, Mexico City, Mexico.
authors.forename: Aracely
authors.initials: A
authors.lastname: Muñoz Bautista
authors.affiliation: Department of Veterinarian Surgery, Specialties Hospital, National Medical Center Century XXI, Mexico City, Mexico.
authors.forename: Maria Lourdes
authors.initials: ML
authors.lastname: Altamirano Castañeda
authors.affiliation: Department of Endoscopy, Specialties Hospital, National Medical Center Century XXI, Mexico City, Mexico.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Blanco-Velasco
authors.affiliation: Department of Endoscopy, Specialties Hospital, National Medical Center Century XXI, Mexico City, Mexico.
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: Blancas Valencia