CTNND1 is involved in germline predisposition to early-onset gastric cancer by affecting cell-to-cell interactions.

BACKGROUND: CDH1 and CTNNA1 remain as the main genes for hereditary gastric cancer. However, they only explain a small fraction of gastric cancer cases with suspected inherited basis. In this study, we aimed to identify new hereditary genes for early-onset gastric cancer patients (EOGC; < 50 years old). METHODS: After germline exome sequencing in 20 EOGC patients and replication of relevant findings by gene-panel sequencing in an independent cohort of 152 patients, CTNND1 stood out as an interesting candidate gene, since its protein product (p120ctn) directly interacts with E-cadherin. We proceeded with functional characterization by generating two knockout CTNND1 cellular models by gene editing and introducing the detected genetic variants using a lentiviral delivery system. We assessed ß-catenin and E-cadherin levels, cell detachment, as well as E-cadherin localization and cell-to-cell interaction by spheroid modeling. RESULTS: Three CTNND1 germline variants [c.28_29delinsCT, p.(Ala10Leu); c.1105C > T, p.(Pro369Ser); c.1537A > G, p.(Asn513Asp)] were identified in our EOGC cohorts. Cells encoding CTNND1 variants displayed altered E-cadherin levels and intercellular interactions. In addition, the p.(Pro369Ser) variant, located in a key region in the E-cadherin/p120ctn binding domain, showed E-cadherin mislocalization. CONCLUSIONS: Defects in CTNND1 could be involved in germline predisposition to gastric cancer by altering E-cadherin and, consequently, cell-to-cell interactions. In the present study, CTNND1 germline variants explained 2% (3/172) of the cases, although further studies in larger external cohorts are needed.

Effect of the SARS-CoV-2 pandemic on colorectal cancer diagnosis and prognosis.

BACKGROUND AND STUDY AIMS: Our aim was to determine the impact of the SARS-CoV-2 pandemic on the diagnosis and prognosis of colorectal cancer (CRC). PATIENTS AND METHODS: This prospective cohort study included individuals diagnosed with CRC between March 13, 2019 and June 20, 2021 across 21 Spanish hospitals. Two time periods were compared: prepandemic (from March 13, 2019 to March 13, 2020) and pandemic (from March 14, 2020 to June 20, 2021, lockdown period and 1 year after lockdown). RESULTS: We observed a 46.9% decrease in the number of CRC diagnoses (95% confidence interval (CI): 45.1%-48.7%) during the lockdown and 29.7% decrease (95% CI: 28.1%-31.4%) in the year after the lockdown. The proportion of patients diagnosed at stage I significantly decreased during the pandemic (21.7% vs. 19.0%; p = 0.025). Centers that applied universal preprocedure SARS-CoV-2 PCR testing experienced a higher reduction in the number of colonoscopies performed during the pandemic post-lockdown (34.0% reduction; 95% CI: 33.6%-34.4% vs. 13.7; 95% CI: 13.4%-13.9%) and in the number of CRCs diagnosed (34.1% reduction; 95% CI: 31.4%-36.8% vs. 26.7%; 95% CI: 24.6%-28.8%). Curative treatment was received by 87.5% of patients diagnosed with rectal cancer prepandemic and 80.7% of patients during the pandemic post-lockdown period (p = 0.002). CONCLUSIONS: The COVID-19 pandemic has led to a decrease in the number of diagnosed CRC cases and in the proportion of stage I CRC. The reduction in the number of colonoscopies and CRC diagnoses was higher in centers that applied universal SARS-CoV-2 PCR screening before colonoscopy. In addition, the COVID-19 pandemic has affected curative treatment of rectal cancers.

Applicability of the Barcelona scale to assess the quality of cleanliness of mucosa at esophagogastroduodenoscopy / Aplicabilidad de la escala Barcelona para valorar la calidad de la limpieza de la mucosa en la esofagogastroduodenoscopia

Background and objectives There are few scales with prospective validation for the assessment of the upper gastrointestinal mucosal cleanliness during an esophagogastroduodenoscopy (EGD). The aim of this study was to develop a valid and reproducible cleanliness scale for use during an EGD. Methods We developed a cleanliness scale (Barcelona scale) with a score (0–2 points) of five segments of the upper gastrointestinal tract with thorough cleaning techniques (esophagus, fundus, body, antrum, and duodenum). First, 125 photos (25 of each area) were assessed, and a score was assigned to each image by consensus among 7 experts endoscopists. Subsequently, 100 of the 125 images were selected and the inter- and intra-observer variability of 15 previously trained endoscopists was evaluated using the same images at two different times. Results In total, 1500 assessments were performed. In 1336/1500 observations (89%) there was agreement with the consensus score, with a mean kappa value of 0.83 (0.45–0.96). In the second evaluation, in 1330/1500 observations (89%) there was agreement with the consensus score, with a mean kappa value of 0.82 (0.45–0.93). The intra-observer variability was 0.89 (0.76–0.99). Conclusions The Barcelona cleanliness scale is a valid measure and reproducible with minimal training. Its application in clinical practice is a significant step to standardize the quality of the EGD. (AU)

Introducción Existen pocas escalas validadas prospectivamente para evaluar la limpieza de la mucosa esofagogastroduodenal durante la endoscopia digestiva alta (EDA). El objetivo de este estudio fue desarrollar una escala válida y reproducible para su uso en la realización de una EDA. Métodos Desarrollamos una escala de limpieza (escala Barcelona) en la que se aplicó una puntuación de 0 a 2 a cinco áreas del tracto digestivo superior (esófago, fundus, cuerpo, antro y duodeno) después de haber realizado todas las maniobras de lavado necesarias. Inicialmente, se evaluaron 125 fotos (25 de cada área) y se asignó una puntuación (de 0 a 2) a cada una por consenso entre siete endoscopistas. Posteriormente, se seleccionaron 100 de las 125 fotografías y se evaluó la variabilidad inter e intraobservador de 15 endoscopistas previamente formados utilizando las mismas imágenes en dos momentos diferentes. Resultados Se efectuaron un total de 1.500 observaciones. En 1.336/1.500 de ellas (89%) hubo coincidencia con la puntuación del consenso, siendo el valor medio de kappa de 0,83 (0,45-0,96). En la segunda evaluación, en 1.330/1.500 observaciones (89%) hubo coincidencia con la puntuación del consenso, siendo el valor medio de kappa de 0,82 (mínimo 0,45 y máximo 0,93). La variabilidad intraobservador fue de 0,89 (0,76-0,99). Conclusiones La escala de limpieza Barcelona es una medida válida y reproducible con un mínimo entrenamiento. Su uso en la práctica clínica podría ser un paso significativo para estandarizar la calidad de la EDA. (AU)

Colonoscopy Satisfaction and Safety Questionnaire based on patient experience (CSSQP): A valuable quality tool for all colonoscopies / Cuestionario de Satisfacción y Seguridad de la Colonoscopia basado en la experiencia del Paciente (CSSQP): una valiosa herramienta de calidad para todas las colonoscopias

Introduction The Colonoscopy Satisfaction and Safety Questionnaire based on Patient experience (CSSQP) was recently developed and validated within a Bowel Cancer Screening Program. We aimed to identify factor related to patient experience through the CSSQP, including all indications for colonoscopy. Indicators of satisfaction and perceived safety with colonoscopy were also assessed to compare the different centers. Methods Multicenter study in nine Spanish hospitals. Consecutive patients who had undergone a colonoscopy completed the CSSQP adding a novel item on bowel preparation. Factors related to patient experiences and data from non-respondents were analyzed. Results Of 2200 patients, 1753 filled out the questionnaire (response rate 79.7%, sample error 2%). Patients whose colonoscopy indication was a primary colorectal cancer screening (OR: 1.68, 95% CI: 1.15–2.44, p=0.007) or due to a +FIT (OR: 1.73, 95% CI: 1.18–2.53) reported higher satisfaction than patients with gastrointestinal symptoms. In addition, college-educated patients (OR: 2.11, 95% CI: 1.25–3.56) were more likely to report better overall satisfaction than patients with lower education level. Significant differences were observed in the majority of the CSSQP items between centers. Safety incidents were reported by 35 (2%) patients, and 176 (10%) patients reported that they received insufficient information. Conclusion The CSSQP identifies several significant factors on satisfaction and perceived safety in patients referred for colonoscopy for any reason. The CSSQP also allows comparison of patient-identified colonoscopy quality indicators between centers (AU)

Introducción El Cuestionario de Satisfacción y Seguridad de la Colonoscopia basado en la experiencia del Paciente (CSSQP) ha sido desarrollado y validado recientemente en pacientes del Programa de cribado de cáncer colorrectal (CCR). El objetivo del estudio fue identificar los factores relacionados con la experiencia de los pacientes a través del CSSQP, incluyendo todas las indicaciones de la colonoscopia. Además, se evaluaron los factores relacionados con la satisfacción y la seguridad del paciente con el fin de comparar diferentes departamentos. Métodos Estudio multicéntrico de nueve hospitales españoles en el que se incluyeron pacientes consecutivos que completaron el CSSQP incorporando un nuevo ítem sobre la preparación intestinal. Se analizaron los factores relacionados con la experiencia de los pacientes y los datos de los no respondedores. Resultados De 2.200 pacientes, 1.753 completaron el cuestionario (tasa de respuesta del 79,7%, error muestral del 2%). Los pacientes en los que la indicación era por cribado de CCR (OR: 1,68; IC 95%: 1,15-2,44; p=0,007) o por FIT positivo (OR: 1,73; IC 95%: 1,18-2,53) informaron mayor satisfacción que en aquellos que se solicitó la colonoscopia por síntomas gastrointestinales. Además, los pacientes con estudios universitarios (OR: 2,11; IC 95%: 1,25-3,56) informaron mayor satisfacción que aquellos con menor nivel de estudios. Se observaron diferencias significativas en la mayoría de los ítems del CSSQP entre los centros participantes. Treinta y cinco (2%) pacientes reportaron incidentes de seguridad y 176 (10%) reconocieron haber recibido información insuficiente. Conclusiones El CSSQP identifica los factores determinantes que influyen en la satisfacción y la seguridad de los pacientes a los que se les realiza colonoscopia por cualquier indicación. Además, permite comparar los indicadores de calidad de la colonoscopia desde la perspectiva del paciente entre los distintos centros (AU)

Findings in the distal and proximal colon in colonoscopy screening after positive FIT and related pre-procedure factors

Background: colonoscopy is the gold standard method forthe early diagnosis and prevention of colorectal cancer(CRC). Screening programs include immune determinationof blood in feces. Regardless of the method used, proximalcolon lesions appear to be detected less frequently.Objective: to analyze the characteristics of proximal anddistal lesions and possible predisposing factors.Methods: a cross-sectional study was performed of 692patients from the CRC screening program with fecal immunological test (FIT) ≥ 100 ngHb/ml (October 2017-October2018). The right colon was examined twice as patients wereparticipating in a randomized clinical trial to re-evaluatethe right colon by forward-viewing endoscope or proximalretroflexion. The adenoma detection rate (ADR), advancedneoplasia (AN) and CRC in the proximal and distal colon,histological and morphological characteristics in each section were analyzed.Results: in the study, 52.9 % of the patients were male, witha mean age of 59.5 years (standard deviation [SD]: 7.6);1,490 polyps were found and the ADR was 57.7 % (distal42 % and proximal 37 %). Detection rates were 45.8 % forAN, 40.9 % for advanced adenomas, 5.2 % for advancedsessile serrated lesions (SSL) and CRC was diagnosed in4.8 % of patients. Males had more AN than females. Themean age of patients with AN was significantly higher. ANwere associated with smoking and alcohol consumption (p = 0.0001). Globally, FIT levels were higher in patientswith AN (p = 0.003). Sixty-six per cent of cancers were distally located and 61.3 % of CRC were diagnosed in the earlystages.Conclusions: in an average-risk asymptomatic populationundergoing colonoscopy after positive FIT, AN were morecommon in the distal colon in males, older patients, smokers and those with alcohol intake. (AU)

Documento de posicionamiento de la AEG, la SEED y la SEAP sobre cribado de cáncer gástrico en poblaciones con baja incidencia / Gastric cancer screening in low incidence populations: Position statement of AEG, SEED and SEAP

Este documento de posicionamiento, auspiciado por la Asociación Española de Gastroenterología, la Sociedad Española de Endoscopia Digestiva y la Sociedad Española de Anatomía Patológica, tiene como objetivo establecer recomendaciones para el cribado del cáncer gástrico (CG) en poblaciones con incidencia baja, como la española. Para establecer la calidad de la evidencia y los niveles de recomendación se ha utilizado la metodología basada en el sistema GRADE (Grading of Recommendations Assessment, Development and Evaluation). Se obtuvo el consenso entre expertos mediante un método Delphi. El documento evalúa el cribado en población general, individuos con familiares con CG y lesiones precursoras de CG (LPCG). El objetivo de las intervenciones debe ser la reducción de la mortalidad por CG. Se recomienda el uso de la clasificación OLGIM y determinar el subtipo de metaplasia intestinal (MI) para evaluar las LPCG. No se recomienda establecer cribado poblacional endoscópico de CG ni de Helicobacter pylori. Sin embargo, el documento establece una recomendación fuerte para el tratamiento de H.pylori si se detecta la infección, y su investigación y tratamiento en individuos con antecedentes familiares de CG o con LPCG. En cambio, no se recomienda el uso de test serológicos para detectar LPCG. Se sugiere cribado endoscópico únicamente en los individuos con criterios de CG familiar. En cuanto a los individuos con LPCG, solo se sugiere vigilancia endoscópica ante MI extensa asociada a algún factor de riesgo adicional (MI incompleta y/o antecedentes familiares de CG) tras la resección de lesiones displásicas o en pacientes con displasia sin lesión visible tras una endoscopia digestiva alta de calidad con cromoendoscopia

This positioning document, sponsored by the Asociación Española de Gastroenterología, the Sociedad Española de Endoscopia Digestiva and the Sociedad Española de Anatomía Patológica, aims to establish recommendations for the screening of gastric cancer (GC) in low incidence populations, such as the Spanish. To establish the quality of the evidence and the levels of recommendation, we used the methodology based on the GRADE system (Grading of Recommendations Assessment, Development and Evaluation). We obtained a consensus among experts using a Delphi method. The document evaluates screening in the general population, individuals with relatives with GC and subjects with GC precursor lesions (GCPL). The goal of the interventions should be to reduce GC related mortality. We recommend the use of the OLGIM classification and determine the intestinal metaplasia (IM) subtype in the evaluation of GCPL. We do not recommend to establish endoscopic mass screening for GC or Helicobacter pylori. However, the document strongly recommends to treat H.pylori if the infection is detected, and the investigation and treatment in individuals with a family history of GC or with GCPL. Instead, we recommend against the use of serological tests to detect GCPL. Endoscopic screening is suggested only in individuals that meet familial GC criteria. As for individuals with GCPL, endoscopic surveillance is only suggested in extensive IM associated with additional risk factors (incomplete IM and/or a family history of GC), after resection of dysplastic lesions or in patients with dysplasia without visible lesion after a high quality gastroscopy with chromoendoscopy

Valoración de las peticiones de endoscopia para reanudar la actividad durante la pandemia por SARS-CoV-2: denegación de las no indicadas y priorización de las aceptadas / No disponible

INTRODUCCIÓN: la pandemia mundial por SARS-CoV-2 obligó a paralizar las unidades de endoscopia. Previamente a la reanudación de la actividad endoscópica diseñamos un protocolo de valoración de gastroscopias y colonoscopias, desprogramadas durante la pandemia, denegando las no indicadas y priorizando las indicadas. MÉTODOS: establecimos dos tipos de denegación: a) contexto covid-19 en ≤ 50 años sin síntomas de alarma y baja probabilidad de hallazgos endoscópicos relevantes; y b) contexto inadecuado por no ser acordes con las guías o protocolos clínicos. Las denegaciones se archivaron en la historia clínica del paciente. Clasificamos las adecuadas en preferentes, convencionales y seguimiento. Comparamos las denegadas por especialidad. Valoramos los hallazgos de las preferentes. RESULTADOS: valoramos 1.658 peticiones (44 % gastroscopias, 56 % colonoscopias) entre el 16 marzo y el 30 junio de 2020. Se consideraron adecuadas 1.164 (70 %), de ellas preferentes el 8,5 %, convencionales el 48 %, seguimiento el 43 % y no valorables el 0,5 %. Se denegaron 494 (30 %): 20 % "contexto covid-19" y 80 % "contexto inadecuado". Los motivos de denegación en las gastroscopias fueron: seguimiento de lesiones (33 %), síntomas insuficientemente estudiados (20 %) y síntomas recidivantes con gastroscopia previa (18 %). Los motivos de denegación en las colonoscopias fueron: vigilancia pospolipectomía (25 %), cáncer colorrectal intervenido (21 %) y antecedentes familiares de cáncer (13 %). Encontramos diferencias significativas en la denegación según la especialidad: Cirugía General (52 %), Hematología (37 %) y Atención Primaria (29 %). Un 31 % de las preferentes mostraron hallazgos relevantes. CONCLUSIONES: un 24 % de nuestras endoscopias son discordantes con las recomendaciones científicas. Su denegación y la priorización de las adecuadas optimizan la utilización de recursos

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Satisfaction with care in colorectal cancer patients: inpatient versus outpatient study

Background: satisfaction with healthcare is focused on the patient and is known as "patient-centered care". However, user satisfaction is not always synonymous with good care. Healthcare practitioners should determine and understand what patients need and expect in order to improve the quality of care. Aims: the main objective of this study was to determine the perceived quality of care of patients diagnosed with colorectal cancer in our unit. Methods: a cross-sectional study was performed in all patients diagnosed with colorectal cancer (CRC) that underwent staging studies and were hospitalized in the Gastroenterology Department from May 2013 to October 2013. Furthermore, outpatients with rapid consultations for CRC staging from November 2013 to November 2014 were also included. Two questionnaires were administered: a) a survey of 20 questions with closed responses regarding the competence of treating physicians and nurses, the information received and the waiting time; b) the European Organization for Research and Treatment of Cancer (EORTC) QLQ-INFO25: information on the disease, medical tests, treatment and other services, with eight single items. Results: there were no differences in the perceived healthcare quality, delays in starting treatment, the tumor stage, symptoms (performance status) or the time spent studying the disease. In-patients and those with advanced disease started treatment earlier than outpatients and those with disease stage I or II. Likewise, outpatients perceived a better psychological support. Conclusions: outpatient study did not reduce the quality of care and did not delay treatment

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Over-the-scope-clip: Endoscopic treatment of Boerhaave syndrome / Over-the-scope-clip: tratamiento endoscópico del síndrome de Boerhaave

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Vigilancia tras resección de pólipos de colon y de cáncer colorrectal. Actualización 2018 / Endoscopic surveillance after colonic polyps and colorrectal cancer resection. 2018 update

La evidencia disponible para estratificar el riesgo de presentar un cáncer colorrectal metacrónico tras la extirpación de pólipos colorrectales y determinar los intervalos de vigilancia es limitada y se basa en estudios observacionales. No obstante, a la espera de nuevas evidencias, es necesario unificar los criterios del seguimiento endoscópico en nuestro medio. Por ello, desde las principales sociedades científicas involucradas en el manejo de estos pacientes, como son la Asociación Española de Gastroenterología, la Sociedad Española de Medicina Familiar y Comunitaria, la Sociedad Española de Endoscopia Digestiva y el Grupo de Cribado de Cáncer Colorrectal de la Sociedad Española de Epidemiología, se ha creado este documento de consenso, que se encuentra incluido en el capítulo 10 de la «Guía de Práctica Clínica de Diagnóstico y Prevención del Cáncer Colorrectal. Actualización 2018». A continuación, se presentarán importantes novedades respecto a la edición previa publicada en 2009. En primer lugar, se establecen situaciones que requieren y no requieren vigilancia endoscópica y se elimina la necesidad de realizar seguimiento en individuos que no presentan un riesgo especial de cáncer de colon metacrono. En segundo lugar, se establecen recomendaciones de vigilancia endoscópica en individuos con pólipos serrados. Finalmente, a diferencia de la edición anterior, se dan recomendaciones de vigilancia endoscópica en individuos intervenidos por cáncer colorrectal. Paralelamente, supone un avance sobre la guía europea de calidad en el cribado del cáncer colorrectal, ya que elimina la división entre grupo de riesgo medio y grupo de riesgo alto, lo que supone la eliminación de una proporción considerable de colonoscopias de vigilancia precoz. Finalmente, se dan recomendaciones claras sobre la ausencia de necesidad de seguimiento en el grupo de riesgo bajo, para el que la guía europea mantenía cierta ambigüedad

There is limited scientific evidence available to stratify the risk of developing metachronous colorectal cancer after resection of colonic polyps and to determine surveillance intervals and is mostly based on observational studies. However, while awaiting further evidence, the criteria of endoscopic follow-up needs to be unified in our setting. Therefore, the Spanish Association of Gastroenterology, the Spanish Society of Family and Community Medicine, the Spanish Society of Digestive Endoscopy, and the Colorectal Cancer Screening Group of the Spanish Society of Epidemiology, have written this consensus document, which is included in chapter 10 of the "Clinical Practice Guideline for Diagnosis and Prevention of Colorectal Cancer. 2018 Update". Important developments will also be presented as regards the previous edition published in 2009. First of all, situations that require and do not require endoscopic surveillance are established, and the need of endoscopic surveillance of individuals who do not present a special risk of metachronous colon cancer is eliminated. Secondly, endoscopic surveillance recommendations are established in individuals with serrated polyps. Finally, unlike the previous edition, endoscopic surveillance recommendations are given in patients operated on for colorectal cancer. At the same time, it represents an advance on the European guideline for quality assurance in colorectal cancer screening, since it eliminates the division between intermediate risk group and high risk group, which means the elimination of a considerable proportion of colonoscopies of early surveillance. Finally, clear recommendations are given on the absence of need for follow-up in the low risk group, for which the European guidelines maintained some ambiguity

Colitis infecciosa nodular: un hallazgo inusual / Nodular colitis: endoscopic image an unusual finding

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Comparación entre la insuflación con aire ambiente o con dióxido de carbono durante la colonoscopia en pacientes sedados con propofol / Comparison between insufflation with air or carbon dioxide during the colonoscopy in sedated patients with propofol

Objetivos: comparar la intensidad del dolor experimentado tras una colonoscopia con aire ambiente o con dióxido de carbono (CO2) y evaluar la seguridad del CO2 en pacientes con sedación moderada o profunda. Materiales y métodos: individuos sometidos a una colonoscopia ambulatoria, sin enfermedad respiratoria severa ni obesidad mórbida, randomizados a grupo "aire" o "CO2". Se recogieron diferentes variables antes, durante y tras la colonoscopia. Todos los pacientes fueron monitorizados mediante capnografía y pulsioximetría. Posteriormente cada paciente puntuó mediante una escala visual numérica la intensidad del dolor experimentado en diferentes momentos tras la colonoscopia. Resultados: 141 pacientes incluidos en grupo "aire" (hombres/ mujeres 63/78, rango edad 24-83) y 129 en "CO2" (hombres/mujeres 59/70, rango edad 24-82). No existieron diferencias significativas entre ambos grupos a excepción del mayor número de exploraciones realizadas por un endoscopista en formación en el grupo "aire" en comparación con las realizadas por endoscopistas experimentados. El CO2 en aire espirado, los episodios de desaturación de oxígeno y las dosis de propofol o midazolam empleadas fueron similares en ambos grupos. No existieron episodios de hipercapnia severos ni complicaciones clínicamente relevantes. El dolor experimentado en el grupo "aire" fue significativamente mayor a los 15 minutos, 1, 3 y 6 horas tras la colonoscopia, igualándose a las 24 horas. Tras la realización de un análisis multivariante según el tipo de endoscopista (experimentado o en formación) las diferencias observadas en la intensidad del dolor en cada grupo se mantuvieron. Conclusiones: a) el uso de CO2 en la colonoscopia causa significativamente menos dolor en las siguientes 6 horas; b) su uso en pacientes con sedación moderada o profunda es seguro; y c) la realización de la técnica no se ve modificada ni sus tiempos reducidos(AU)

Objectives: compare the intensity of pain experienced after colonoscopy with air or with CO2 and evaluate the safety of CO2 in colonoscopies performed with moderate/deep sedation. Materials and methods: individuals undergoing ambulatory colonoscopy without exclusion criteria (severe respiratory disease, morbid obesity) were randomized in air or CO2 group. We recorded different variables prior to, during and upon completion of the colonoscopy, performing monitoring using pulse oximetry and capnography. Each patient rated, using a visual numeric scale, the intensity of post-colonoscopy pain at different moments. Results: 141 individuals in the air group (sex M/F 63/78, age 24-83) and 129 in the CO2 group (sex M/F 59/70, age 24-82). No significant differences existed in the recorded variables in both groups except for the greater number of explorations performed by an endoscopist in training (TE) in the air group compared to those by a more experienced endoscopist (SE). CO2 in expired air, episodes of oxygen desaturation and of apnoea and dose of propofol, of midazolam were similar in both groups. No episodes of hypercapnea or any complication requiring cardiopulmonary resuscitation measures were recorded. The pain in the air group was significantly higher at 15 minutes and at 1, 3 and 6 hours after the endoscopy, equalising at 24 hours. After multivariant adjustment for type of doctor (TE vs. SE) the differences observed in pain intensity for each group were maintained. Conclusions: a) the use of CO2 in colonoscopy causes significantly less pain in the first 6 hours after the procedure; b) its use in patients with moderate/deep sedation is safe; and c) performance of the endoscopic technique is not modified, nor are times reduced(AU)