Warm Water Cools Colonoscopy Pain Scores

The October issue of GIE: Gastrointestinal Endoscopy features the results of two randomized controlled trials of unsedated colonoscopy comparing water infusion versus air insufflation to distend the colon.

Click here to read about the first study, "Improved Outcomes in Scheduled Unsedated Colonoscopy by the Water Method."

Warm Water Infusion versus Air Insufflation for Unsedated Colonoscopy

A randomized controlled trial by researchers at Valduce Hosipital in Como, Italy, tested the hypothesis (proposed by observational studies by the Veterans Affairs Healthcare System researchers in California) that warm water infusion during the insertion phase of colonoscopy could increase the proportion of patients able to complete colonoscopy without sedation and could improve overall tolerance compared to the traditional procedure using air insufflation during unsedated colonoscopy.

Between April and July 2009, a total of 230 patients were randomly assigned to the water group (116 patients) or to the air group (114 patients). The main outcome measurements were the percentage of patients requiring sedation/analgesia, and pain and tolerance scores were assessed when the patients were discharged. Three endoscopists (two highly trained and one trainee) performed the procedures.

The patients, but not the endoscopists, were blinded to the method. At regular intervals during the colonoscopy, patients were asked by the endoscopist and a gastrointestinal assistant about abdominal discomfort, pain and whether they wanted sedation/analgesia. After the procedure at discharge, an independent, blinded interviewer assessed patient pain, tolerance and willingness to repeat the procedure under the same circumstances.

The study found that the proportion of patients requesting sedation/analgesia during the procedure was 12.9 percent in the water group and 21.9 percent in the air group. Pain scores were 28 for the water group and 39 for the air group, based on a scale of zero (no pain) and 100 (worst pain ever). Tolerance was based on a similar scale and scores were 10 for the water group and 14 for the air group.

At discharge, 90.5 percent of the patients in the water group said they would be willing to repeat the procedure under the same circumstances versus 81.6 percent of patients in the air group.

Cecal intubation rates were 94 percent in the water group and 95.6 percent in the air group. The adenoma detection rates were 25 percent for the water group and 40.1 percent for the air group; a result that is in contrast to the Veterans Affairs study.

The researchers concluded that this randomized controlled trial shows that the use of warm water infusion instead of air insufflation during colonoscopy is associated with a decreased number of patients requiring on-demand sedation and significantly increases the overall tolerance of the procedure without compromising the success rate of cecal intubation.

They do not believe that unsedated colonoscopy may replace sedated procedures; however, the technique might play a role in improving acceptance and tolerability of colonoscopy for patients willing or needing to undergo unsedated procedures. The lower adenoma detection rate associated with the water method, never reported before, is a matter of major concern and further evaluation is needed.

In an accompanying editorial about both studies, David H. Robbins, MD, MSc, Center for Advanced Therapeutic Endoscopy, Lenox Hill Hospital, states that, in regards to why there was a lower adenoma detection rate with the water method in the Italian study, “Because more polyps were detected and underwent polypectomy (polyp removal) in the air group, the perceived efficiency of air insufflation was mitigated and no overall procedure time difference was seen…While not significant, the VA study water cohort actually trended toward a higher ADR (adenoma detection rate). Having done a few hydroscopes (water method) myself and reviewing the world literature, I am prepared to go on record and call this particular finding an aberration…”

Dr. Robbins adds that, “For patients who are at higher risk of, or fear, anesthesia-related complications, have no escort, want to interact with their physician during the examination, or need to get back to the trading floor that afternoon, there is little doubt that we have another option.”

Source: American Society for Gastrointestinal Endoscopy