title: Learning process and improvement of point-of-care ultrasound technique for subxiphoid visualization of the inferior vena cava.
abstract: BACKGROUND
  Medical residents' training in ultrasonography usually follows the recommendations of the American College of Emergency Physicians (ACEP), even though these do not provide specific technical guidelines. Adequate training is considered to require 25 practical iterations in the majority of ultrasound procedures. However, the effectiveness of this approach has not been verified experimentally. We set out to determine the number of repetitions required for an acceptable ultrasound procedure of the inferior vena cava (IVC), as an important and emerging ultrasound procedure in cardiology.
  
  
  METHODS
  Using three human models, each of eight medical residents in the Emergency Medicine (EM) Program at the Universidad del Rosario performed 25 iterations of the recommended procedure, with image quality evaluation by an EM physician expert in the technique. Logistic regression analysis was used to determine the lowest number of repetitions required to achieve an adjusted probability of success of 80 and 90 %, respectively.
  
  
  RESULTS
  We obtained 200 ultrasound images. The percentage success by each resident ranged from 52 to 96 %. There was no statistical significance in the relation between gender and success (p = 0.83), but there was an association between year of residency and success (p < 0.001). The average time taken for each procedure was 17.3 s (SD 8.1); there was no association between the time taken and either repetition number or image quality. We demonstrate that eleven repetitions are required to achieve acceptable image quality in 80 %, and that 21 repetitions are required to achieve acceptable image quality in 90 %.
  
  
  CONCLUSIONS
  This is the first study to formally evaluate the effectiveness of recommended training in ultrasound techniques. Our findings demonstrate that training comprising 25 procedural repetitions is easily sufficient to achieve optimal image quality, and they also provide empiric knowledge toward elucidating the times and minimum repetitions needed to acquire and improve ultrasonographic technique in novice operators to a level which fulfills quality requirements for interpretation.
authors.affiliation: Emergency Medicine Specialist, Universidad del Rosario, Bogotá, Colombia.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Gómez Betancourt
authors.affiliation: Epidemiology, Biostatistics and Public Health Research Group, EPIBIOS_UR, Escuela de Medicina y Ciencias de la Salud (EMCS), Universidad del Rosario, Bogotá, Colombia.
authors.forename: José
authors.initials: J
authors.lastname: Moreno-Montoya
authors.affiliation: Epidemiology, Biostatistics and Public Health Research Group, EPIBIOS_UR, Escuela de Medicina y Ciencias de la Salud (EMCS), Universidad del Rosario, Bogotá, Colombia. ana.barragan@urosario.edu.co.
authors.forename: Ana-María
authors.identifier: http://orcid.org/0000-0002-4646-4324
authors.initials: AM
authors.lastname: Barragán González
authors.affiliation: Emergency Medicine Specialist, Universidad del Rosario, Bogotá, Colombia.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Ovalle
authors.affiliation: Chief of the Department of Emergency Medicine and Director of the Simulation Center, Escuela de Medicina y Ciencias de la Salud (EMCS), Universidad del Rosario, Bogotá, Colombia. yury.bustos@urosario.edu.co.
authors.forename: Yury Forlan
authors.initials: YF
authors.lastname: Bustos Martínez
keywords: Colombia; Inferior vena cava; Learning curve; Point-of-care; Residents; Ultrasonography