A Comparison of Air Insufflation, Water Immersion and Water Exchange Colonoscopy in CRC Screening
Condition: Pain; Colorectal Adenomas; Colorectal Cancer
MeSH terms: Adenoma
Study type: Interventional

Summary: 
      Water-aided method for colonoscopy can be broadly subdivided into two major categories. Water
      Immersion (WI), characterized by suction removal of the infused water predominantly during
      the withdrawal phase of colonoscopy, and Water Exchange (WE), characterized by suction
      removal of infused water predominantly during the insertion phase of colonoscopy. Several
      studies showed that WE significantly reduces pain compared to WI and colonoscopy with
      traditional air insufflation (AI), increases the number of unsedated procedures and adenoma
      detection rate (ADR), in particular proximal ADR. This randomized controlled trial will be a
      direct comparison of Air Insufflation, Water Immersion and Water Exchange to test the
      hypothesis that WAC (particularly WE) would significantly decrease pain score during
      colonoscopy in average-risk screening patients. Several other secondary outcomes will also be
      analyzed.
    

Detailed description: 
      Introduction

      Water-aided methods for colonoscopy can be broadly subdivided into two major categories.
      Water Immersion (WI) is characterized by suction removal of the infused water predominantly
      during the withdrawal phase of colonoscopy and Water Exchange (WE) is characterized by
      suction removal of infused water predominantly during the insertion phase of colonoscopy.
      Several studies showed that WE significantly reduces pain compared to WI and colonoscopy with
      traditional air insufflation (AI), increases the number of unsedated procedures and adenoma
      detection rate (ADR), in particular proximal ADR. This randomized controlled trial will be a
      direct comparison of Air Insufflation, Water Immersion and Water Exchange to test the
      hypothesis that WAC (particularly WE) would significantly decrease pain score during
      colonoscopy in average-risk screening patients. Several other secondary outcomes will also be
      analyzed.

      Method

      Examinations will be allocated to Water Exchange, Water Immersion or Air Insufflation during
      the insertion phase of colonoscopy based on a computer generated random list. Procedures will
      be started by 6 board-certified endoscopists, three with experience in 8,000-10,000 and three
      with experience in 2,000-5,000 colonoscopies with AI, 285 with WI and 890 with WE overall.
      High-resolution wide-angle variable-stiffness adult video colonoscopes (Olympus HD 180
      series; Olympus Corp, Hamburg, Germany) will be used. Need to change to a smaller caliber
      colonoscope will be considered ITT failure.

      Patients will have a low volume split dose bowel preparation with 2L of polyethylene glycol
      (PEG) solution or Sodium Picosulfate. Investigators will be blinded to the colon preparation
      used. Before starting the procedure, a questionnaire recording demographic data, previous
      abdominal surgery, co-morbidities and current medications will be administered by the
      endoscopists. The patients, but not endoscopists and assisting nurses, will be blinded to the
      method used. At discharge the patient will be asked to guess which method has been used. If
      no more than half of the responses are correct, patients' blinding will be considered
      adequate.

      Colonoscopy will begin with the patients in the left lateral position, without premedication.

      The withdrawal phase will be identical in all arms of the study using air insufflation to
      obtain adequate distension of the colonic lumen for mucosal inspection, biopsy and/or
      polypectomy.

      Patients randomized to the water-aided colonoscopy group, during the insertion phase after
      reaching the rectosigmoid junction, will have the colon irrigated with water at 37°C
      maintained with a water bath. Infusions will be performed using flushing pumps (Olympus OFP2,
      Olympus, Hamburg, Germany or Velocity irrigation pump, US Endoscopy, OH, USA). There will be
      no restriction of the overall volume of water that can be infused to get adequate lumen
      distention and reach the cecum. With the patient in the left lateral position water infused
      into the colon at the rectal sigmoid junction flows into the descending colon. The weight of
      the water in the left side of the colon straightens the sigmoid segment increasing the ease
      of insertion and reducing the risk of loop formation. The air pump will be turned off to
      avoid inadvertent insufflation.

      Water Immersion will involve the infusion of water during the insertion phase of colonoscopy
      mainly to open the colonic lumen and progress to the cecum immersed in the water environment
      thus created, without attempting to clear the colon contents. Use of water as an adjunct to
      air insufflation to facilitate insertion and removal of infused water predominantly during
      withdrawal are characteristic features of WI. This traditional adjunct facilitates passage
      through the sigmoid colon with severe diverticulosis, speeds arrival to the splenic flexure,
      decreases colonic spasm, minimizes pain, and even enhances cecal intubation in previously
      incomplete colonoscopies. Residual air in the colon will not be removed. The infused water
      and residual feces will be suctioned back only during withdrawal. Air insufflation will be
      allowed if the lumen cannot be seen and the endoscopists judges unsafe to advance the
      colonoscope. It will last no more than 10 seconds and will be recorded in the patient data
      sheet. If more than 3 episodes of air insufflation will be recorded the procedure will be
      considered ITT failure.

      Water Exchange will involve complete exclusion of air insufflation, removal of residual
      colonic air and feces and of infused water predominantly during insertion to assist
      identification of the lumen. WE minimizes loop formation and decreases discomfort. By
      providing salvage cleansing during insertion, WE allows the colonoscopist to devote a greater
      proportion of the withdrawal to inspection. WE will involve the infusion of a sufficient
      amount of water to open the lumen of the colon to allow passage of the instrument, thus
      rendering the colonic lumen a slit to progress with the colonoscope. If the lumen does not
      open, the colonoscope will be slightly retracted and the infusion started again. Part of the
      infused water will be constantly suctioned back exchanging clean for dirty or hazy water.
      Suction of infused water will also be applied when colonoscope insertion proceeds smoothly.
      Air pockets, when encountered, will be always aspirated to collapse the lumen: the absence of
      air space forces the colonoscopist to use water to clear residual feces and to find the way
      through the colon. Removal of the air also shortens the colon and takes out all the sharp
      turns at the flexures and redundant segments, reducing the risk of loop formation: water
      instillation does not elongate the colon as much as air insufflation does. In a collapsed,
      airless colon turbulences created at the tip of the instrument facilitate the removal by
      suction of residual feces adherent to the mucosa. This provides salvage cleansing during the
      insertion phase. After cecal intubation as much residual water as possible will be aspirated
      before beginning the withdrawal phase. During withdrawal scarce amounts of water are left to
      aspirate, and residual water and feces will be suctioned.

      In the AI group, colonoscopy will be performed in the standard fashion, allowing for washing
      as needed. In all groups abdominal compression and position change were applied as needed.

      Cecal intubation will be defined as passage of the tip of the colonoscope to a point proximal
      to the ileocecal valve with adequate visualization of the cecum and appendix orifice. A
      stopwatch will be used to time the procedures. Cecal intubation time will be defined as the
      time for passage of the colonoscope from the rectum to the cecum. The withdrawal phase will
      last at least 6 minutes. Polyp resection will be done during withdrawal in all groups. Time
      for polypectomy or biopsy will add to the total colonoscopy time. Pathology reports of all
      polyps will be reviewed and recorded to evaluate adenoma detection rate (ADR, defined as the
      proportion of subjects with at least one adenoma of any size), the location, the total number
      of adenomas resected per subject (ARR), and the percentage of subjects with advanced
      adenomas. The amount of water infused during insertion and withdrawal, the number of position
      changes and any adverse outcome will be recorded. Cardiopulmonary function will be monitored.
      Significant oxygen desaturation (<85% for >15 seconds) will be recorded. Vagal reaction will
      be defined as heart rate <60 beats per minute accompanied by excessive sweating, nausea
      and/or vomiting.
    

Intervention name(s): Air Insufflation method.; Water Immersion method.; Water Exchange method.
Intervention type(s): Other; Other; Other
Intervention description(s): Colonoscopy will be performed in the standard fashion, with the minimal air insufflation required to aid insertion and allowing for washing as needed. Considered to be standard procedure.; Air will not be insufflated until the cecum is reached. It will be allowed only 3 times and no more than 10 seconds each time (ITT failure if >3) if the lumen cannot be seen. Infusion of water during the insertion phase of colonoscopy mainly to open the colonic lumen and progress to the cecum immersed in the water environment thus created, without attempting to clear the colon contents. Residual air in the colon will not be removed. Infused water and residual feces will be suctioned back predominantly during withdrawal.; Air will not be insufflated until the cecum is reached. Infusion of a sufficient amount of water to render the lumen of the colon a slit to progress with the colonoscope. Part of the infused water will be constantly suctioned back exchanging clean for dirty or hazy water. Suction of water will also be applied when colonoscope insertion proceeds smoothly. Air pockets will be always aspirated to collapse the lumen. After cecal intubation as much residual water as possible will be aspirated before beginning the withdrawal phase. During withdrawal residual water and feces will be suctioned.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: Warm Water Infusion colonoscopy; Water Immersion colonoscopy; Water Exchange colonoscopy; Painless unsedated colonoscopy; Adenoma detection rate; Adenoma resection rate