Impact of water exchange colonoscopy on serum sodium and potassium levels: an observational study.

BACKGROUND: Concerns over the hypothetical adverse effects of water absorption and the disturbance of serum sodium and potassium levels prompted a quality assurance evaluation of water exchange (WE) colonoscopy. AIM: The purpose of this study was to evaluate the balance of water infused and suctioned in WE colonoscopy, and to quantify the acute impact on serum levels of sodium and potassium. METHODS: Prospectively collected quality monitoring data of patients undergoing screening and surveillance colonoscopy at the Sacramento Veterans Affairs Medical Center were analyzed. Measurements were made of volume infused and suctioned during, and blood samples drawn 10 min before the start of and 10 min after completion of WE colonoscopy. Outcome measures included volume of water infused and suctioned, and serum levels of sodium and potassium. RESULTS: A total of 140 patients (134M:6F), mean age of 59, underwent WE colonoscopy. Mean total volume of water infused was 1,839 mL. A negative balance of an average of 22 mL was documented. The mean (standard deviation) values (in meq/L) of serum levels of sodium 139.33 (2.27) and 139.28 (2.32), and potassium 3.86 (0.36) and 3.91 (0.39), before and after colonoscopy, respectively, showed no significant change. CONCLUSION: The WE method allowed most of the water infused during colonoscopy to be recovered by suction at the completion of colonoscopy. Serum sodium and potassium levels did not change significantly within 10 min after completion. The WE method appears to be safe with minimal water retention and is devoid of acute fluctuations in serum levels of sodium and potassium.

Water-aided colonoscopy: a systematic review.

BACKGROUND: Water-aided methods for colonoscopy are distinguished by the timing of removal of infused water, predominantly during withdrawal (water immersion) or during insertion (water exchange). OBJECTIVE: To discuss the impact of these approaches on colonoscopy pain and adenoma detection rate (ADR). DESIGN: Systematic review. SETTING: Randomized, controlled trial (RCT) that compared water-aided methods and air insufflation during colonoscope insertion. PATIENTS: Patients undergoing colonoscopy. INTERVENTION: Medline, PubMed, and Google searches (January 2008-December 2011) and personal communications of manuscripts in press were considered to identify appropriate RCTs. MAIN OUTCOME MEASUREMENTS: Pain during colonoscopy and ADR. RCTs were grouped according to whether water immersion or water exchange was used. Reported pain scores and ADR were tabulated based on group assignment. RESULTS: Pain during colonoscopy is significantly reduced by both water immersion and water exchange compared with traditional air insufflation. The reduction in pain scores was qualitatively greater with water exchange as compared with water immersion. A mixed pattern of increases and decreases in ADR was observed with water immersion. A higher ADR, especially proximal to the splenic flexure, was obtained when water exchange was implemented. LIMITATIONS: Differences in the reports limit application of meta-analysis. The inability to blind the colonoscopists exposed the observations to uncertain bias. CONCLUSION: Compared with air insufflation, both water immersion and water exchange significantly reduce colonoscopy pain. Water exchange may be superior to water immersion in minimizing colonoscopy discomfort and in increasing ADR. A head-to-head comparison of these 3 approaches is required.

Indigocarmine added to the water exchange method enhances adenoma detection - a RCT.

PURPOSE: Chromoendoscopy with dye spray and the water method both increase adenoma detection. HYPOTHESIS: Adding indigocarmine to the water method will enhance further the effectiveness of the latter in adenoma detection. METHODS: Screening colonoscopy was performed with the water method (control) or with 0.008% indigocarmine added (study) by two endoscopists. Randomization was based on computer-generated codes contained in blocks of pre-arranged opaque sealed envelopes. High resolution colonoscopes were used. Upon insertion into the rectum, air was suctioned. With the air pump turned off, water was infused using a blunt needle adaptor connected to the scope channel and a foot pump to facilitate scope insertion until the cecum was reached. Residual stool causing cloudiness was suctioned followed by infusion of clear or colored water (water exchange) to facilitate scope passage with minimal distention of the colonic lumen. Upon seeing the appendix opening under water, water was suctioned and air was insufflated to facilitate inspection on scope withdrawal. STATISTICS: Sample size calculation revealed 168 patients (84/group) needed to be randomized. Study was IRB-approved and registered (NCT01383265). RESULTS: There were no significant differences in mean age, gender distribution, BMI, and family history of colon cancer. Cecal intubation success rate was 100% in both groups. The overall adenoma detection rate was 44% (water only) versus 62% (water with indigocarmine), respectively (p=0.03). One cancer was detected in each group. CONCLUSION: In a RCT, indigocarmine at 0.008% concentration, added to the water method, significantly enhanced further the effectiveness of the latter in detecting adenomas.

The water method significantly enhances detection of diminutive lesions (adenoma and hyperplastic polyp combined) in the proximal colon in screening colonoscopy - data derived from two RCT in US veterans.

PURPOSE: Emerging data indicate a colonoscopist-controlled method is needed to avoid missing proximal colon pre-malignant lesions. Screening colonoscopy does not prevent all proximal colon cancers. Even diminutive lesions in the proximal colon harbor dysplasia. In addition to adenomas (presumptive cancer precursors), recent proposals to reevaluate proximal colon hyperplastic polyps as serrated polyps which could be pre-malignant or harbingers of interval neoplasia dramatize the importance of attending to these lesions. The finding that the water method increased yield of proximal diminutive adenomas prompted assessment of the hypothesis that the water method increases yield of all proximal diminutive lesions (adenoma and hyperplastic polyp) in screening cases. METHODS: Two RCT assessed the water method with primary outcome of completion of unsedated colonoscopy when the option of scheduled, unsedated or sedation on demand was used. Diminutive (<10 mm) lesions proximal to the splenic flexure were tracked. RESULTS: In screening cases, 31% and 6% of the water and air group had at least one proximal diminutive lesion (p=0.0012). Regression analysis revealed withdrawal time, method and volume of water used were significant predictors of proximal diminutive lesions. Effect of the water method on detection of proximal diminutive lesions was independent of age, body mass index, endoscopist, sedation, cecal intubation rate, bowel cleanliness score on withdrawal and total procedure time. LIMITATION: Male subject predominance, analysis of secondary outcomes of pooled RCT data. CONCLUSION: The hypothesis that the water method effectively enhances proximal diminutive lesion detection in screening colonoscopy in diverse clinical settings should be tested.

The water method combined with chromoendoscopy enhances adenoma detection.

BACKGROUND: The water method is easy-to-learn and improves colonoscopy outcomes. Dye-spray chromoendoscopy enhances ADR but has not been widely accepted for routine application in screening or surveillance colonoscopy. HYPOTHESIS: With dye added to the water used in the water method, ADR can be enhanced compared with the water or air method alone. OBJECTIVE: To compare ADR determined by the air method, water method alone, and water method with indigo carmine (0.008%) added. DESIGN: Review of prospectively collected data in a performance improvement program. SETTING: VA endoscopy unit. PATIENT: Screening or surveillance colonoscopy. METHODS: Patients (n=50/group) underwent colonoscopy with each of the three methods. Water method involved warm water infusion in lieu of air insufflation coupled with removal of residual air by suction and residual feces by water exchange. ADR and procedural data were collected prospectively to monitor performance. MAIN OUTCOME MEASUREMENTS: ADR. RESULTS: ADR in the air method, water method alone and water method with indigo carmine were 36%, 40% and 62%, respectively. Water method with indigo carmine produced significantly higher ADR than the air or water method alone (p<0.05). LIMITATIONS: Non-randomized data, single VA site, retrospective comparison. Absence of significant difference between air and water methods could be a type II error due to small number of patients CONCLUSIONS: The approach with indigo carmine added to the water used in the water method yielded significantly higher ADR than the water or the air method alone. The data suggest that a prospective RCT to compare the different methods is warranted.

Retrospective analysis showing the water method increased adenoma detection rate - a hypothesis generating observation.

BACKGROUND: A water method developed to attenuate discomfort during colonoscopy enhanced cecal intubation in unsedated patients. Serendipitously a numerically increased adenoma detection rate (ADR) was noted. OBJECTIVE: To explore databases of sedated patients examined by the air and water methods to identify hypothesis-generating findings. DESIGN: Retrospective analysis. SETTING: VA endoscopy center. PATIENTS: creening colonoscopy. INTERVENTIONS: From 1/2000-6/2006 the air method was used - judicious air insufflation to permit visualization of the lumen to aid colonoscope insertion and water spray for washing mucosal surfaces. From 6/2006-11/2009 the water method was adopted - warm water infusion in lieu of air insufflation and suction removal of residual air to aid colonoscope insertion. During colonoscope withdrawal adequate air was insufflated to distend the colonic lumen for inspection, biopsy and polypectomy in a similar fashion in both periods. Main outcome measurements: ADR. RESULTS: The air (n=683) vs. water (n=495) method comparisons revealed significant differences in overall ADR 26.8% (183 of 683) vs. 34.9% (173 of 495) and ADR of adenomas >9 mm, 7.2% vs. 13.7%, respectively (both P<0.05, Fisher's exact test). LIMITATIONS: Non-randomized data susceptible to bias by unmeasured parameters unrelated to the methods. CONCLUSION: Confirmation of the serendipitous observation of an impact of the water method on ADR provides impetus to call for randomized controlled trials to test hypotheses related to the water method as an approach to improving adenoma detection. Because of recent concerns over missed lesions during colonoscopy, the provocative hypothesis-generating observations warrant presentation.

The water method significantly enhances proximal diminutive adenoma detection rate in unsedated patients.

BACKGROUND: Colonoscopy has been reported to fail to prevent some post screening colonoscopy incident cancers or minimize cancer mortality in the proximal colon. These reports question the effectiveness of colonoscopy in detecting all proximal adenomas. Diminutive ones which can be obscured by residual feces are particularly at risk. The water method provides salvage cleansing of sub-optimal preparations. OBJECTIVE: To test the hypothesis that the water method enhances proximal diminutive adenoma detection rate (ADR). DESIGN: The data bases of two parallel RCT were combined and analyzed. SETTING: Two Veterans Affairs endoscopy units. PATIENT AND METHODS: The water and air methods were compared in these two parallel RCT examining unsedated patients. MAIN OUTCOME MEASUREMENTS: The combined data on diminutive and overall ADR in the proximal colon, overall ADR, cecal intubation rate, withdrawal time and global bowel cleanliness score. RESULTS: Data in the water (n=92) and the air (n=90) groups were assessed. The water method yielded a significantly higher proximal diminutive ADR, 28.3% vs. 14.4% (p=0.0298); cecal intubation rate, 99% vs. 90% (p=0.0091); mean withdrawal time 19 (10) vs. 15 (8) min (p=0.0065) and mean global bowel cleanliness score during withdrawal, 2.6 (0.7) vs. 2.3 (0.6) (p=0.0032). Increase in proximal overall ADR in the water group approached significance, 29.3% vs. 16.7% (p=0.0592). LIMITATION: Small number of predominantly male veterans. CONCLUSION: The significantly higher cecal intubation rate, longer mean withdrawal time and better mean global bowel cleanliness score favor the outcome of significantly enhanced proximal diminutive ADR in the water group.

Options of sedation or no sedation for colonoscopy - the perspective of the GI nurses and technicians.

OBJECTIVE: Nurses (patient-advocates) and technicians (member of colonoscopy team) collected data on patient discomfort and evaluated various options of sedation or no sedation associated with the air and water methods for performing colonoscopy. METHOD: Veterans participated in studies comparing air and water method colonoscopy. Options using minimal or on demand sedation were evaluated. RESULTS: Compared with the air method, the water method was associated with significantly lower pain scores, higher patient satisfaction ratings and shorter recovery times. On demand sedation was comparable to routine sedation when the water method was used. Patients prefer to be in control of when their medications would be administered during colonoscopy. CONCLUSION: Evaluations by nurses (patient advocates) and technicians (member of colonoscopy team) with experience in assisting patients undergoing colonoscopy using the various options indicate the following. In settings without access to sedation, the water method is ideal for unsedated colonoscopy or extended flexible sigmoidoscopy for screening. Otherwise, the water method and on demand sedation is the most credible combination of options for patient care.

A randomized, controlled trial to confirm the beneficial effects of the water method on U.S. veterans undergoing colonoscopy with the option of on-demand sedation.

BACKGROUND: Sedation for colonoscopy discomfort imposes a recovery-time burden on patients. The water method permitted 52% of patients accepting on-demand sedation to complete colonoscopy without sedation. On-site and at-home recovery times were not reported. OBJECTIVE: To confirm the beneficial effect of the water method and document the patient recovery-time burden. DESIGN: Randomized, controlled trial, with single-blinded, intent-to-treat analysis. SETTING: Veterans Affairs outpatient endoscopy unit. PATIENTS: This study involved veterans accepting on-demand sedation for screening and surveillance colonoscopy. INTERVENTION: Air versus water method for colonoscope insertion. MAIN OUTCOME MEASUREMENTS: Proportion of patients completing colonoscopy without sedation, cecal intubation rate, medication requirement, maximum discomfort (0 = none, 10 = severe), procedure-related and patient-related outcomes. RESULTS: One hundred veterans were randomized to the air (n = 50) or water (n = 50) method. The proportions of patients who could complete colonoscopy without sedation in the water group (78%) and the air group (54%) were significantly different (P = .011, Fisher exact test), but the cecal intubation rate was similar (100% in both groups). Secondary analysis (data as Mean [SD]) shows that the water method produced a reduction in medication requirement: fentanyl, 12.5 (26.8) µg versus 24.0 (30.7) µg; midazolam, 0.5 (1.1) mg versus 0.94 (1.20) mg; maximum discomfort, 2.3 (1.7) versus 4.9 (2.0); recovery time on site, 8.4 (6.8) versus 12.3 (9.4) minutes; and recovery time at home, 4.5 (9.2) versus 10.9 (14.0) hours (P = .049; P = .06; P = .0012; P = .0199; and P = .0048, respectively, t test). LIMITATIONS: Single Veterans Affairs site, predominantly male population, unblinded examiners. CONCLUSION: This randomized, controlled trial confirms the reported beneficial effects of the water method. The combination of the water method with on-demand sedation minimizes the patient recovery-time burden. ( CLINICAL TRIAL REGISTRATION NUMBER: NCT00920751.).

The water method is effective in difficult colonoscopy - it enhances cecal intubation in unsedated patients with a history of abdominal surgery.

BACKGROUND: Colonoscopy in unsedated patients in the US is considered to be difficult. Success rate of cecal intubation is limited by discomfort. Colonoscopy in patients with a history of abdominal surgery is also considered to be difficult due to adhesion-related bowel angulations. The water method has been shown to significantly reduce pain during colonoscopy. OBJECTIVE: To test the hypothesis that the water method enhances the completion of colonoscopy in unsedated patients with a history of abdominal surgery. DESIGN: The data bases of two parallel RCT were combined and analyzed. SETTING: Two Veterans Affairs endoscopy units. PATIENT AND METHODS: The water and air methods were compared in these two parallel RCT examining unsedated patients. Those with a history of abdominal surgery were selected for evaluation. MAIN OUTCOME MEASUREMENTS: Completion of unsedated colonoscopy. RESULTS: Among patients with a history of abdominal surgery, the proportion completing unsedated colonoscopy in the water group (19 of 22) was significantly higher than that (11 of 22) in the air group (p=0.0217, Fisher's exact test). LIMITATIONS: Small number of predominantly male veterans, unblinded colonoscopists, not all types of abdominal surgery (e.g. hysterectomy, gastrectomy) predisposing to difficult colonoscopy were represented. CONCLUSION: This proof-of-principle assessment confirms that in patients with a history of abdominal surgery the water method significantly increases the proportion able to complete unsedated colonoscopy. The water method deserves to be evaluated in patients with other factors associated with difficult colonoscopy.

A randomized, controlled comparison of warm water infusion in lieu of air insufflation versus air insufflation for aiding colonoscopy insertion in sedated patients undergoing colorectal cancer screening and surveillance.

BACKGROUND: Pilot studies using a novel water method to perform screening colonoscopy allowed patients to complete colonoscopy without sedation medications and also significantly increased the cecal intubation success rate. OBJECTIVE: To perform a randomized, controlled trial comparing air insufflation (conventional method) and water infusion in lieu of air insufflation (study method) colonoscopy in minimally sedated patients. HYPOTHESIS: Compared with the conventional method, patients examined by the study method had lower pain scores and required less medication but had a similar cecal intubation rate and willingness to undergo colonoscopy in the future. SETTING: Outpatient colonoscopy in a single Veterans Affairs hospital. METHODS: After informed consent and standard bowel preparation, patients received premedications administered as 0.5-increments of fentanyl (25 microg) and 0.5-increments of Versed (midazolam) (1 mg) plus 50 mg of diphenhydramine. The conventional and the study methods for colonoscopy were implemented as previously described. Additional pain medications were administered at the patients' request. MAIN OUTCOME MEASUREMENTS: Increments of medications, pain scores, cecal intubation, and willingness to repeat colonoscopy. RESULTS: Increments of medications used before reaching the cecum (1.6 +/- 0.2 vs 2.4 +/- 0.2, P < .0027), total increments used (1.8 +/- 0.2 vs 2.5 +/- 0.2, P < .014), and the maximum pain scores (1.3 +/- 0.3 vs 4.1 +/- 0.6, P < .0002) were significantly lower with the water method. Cecal intubation rate (100%) and willingness to undergo a repeat colonoscopy (96%) were similar. LIMITATIONS: Single Veterans Affairs hospital, older male population. CONCLUSION: Water infusion in lieu of air insufflation is superior to air insufflation during colonoscopy in the minimally sedated patients (ClinicalTrials.gov Identifier NCT00785889).

Options for screening colonoscopy without sedation: sequel to a pilot study in U.S. veterans.

BACKGROUND: Sedation on demand combined with a novel water infusion technique enabled 23 of 44 veterans to complete screening colonoscopy without sedation. OBJECTIVE: With use of the usual air insufflation technique, we determined the proportion of patients who could complete colonoscopy without sedation. DESIGN: Retrospective review of prospectively collected data in a performance improvement project to minimize the burden of sedation. SETTING: A Veterans Affairs open access screening colonoscopy program. SUBJECTS: Ninety-three consecutive veterans who accepted on-demand sedation or scheduled no sedation. METHOD: Usual air insufflation during colonoscope insertion. Medications were administered at the veteran's request. RESULTS: Twenty-three veterans chose scheduled unsedated colonoscopy; 22 were completed without sedation. Sedation on demand enabled 54 to complete the procedure without medications; 16 requested medications to complete colonoscopy. Nurses' expectations indicated that the choices were credible options. CONCLUSIONS: Options for screening colonoscopy without sedation combined with usual air insufflation are feasible among U.S. veterans. Confirmation by randomized controlled trial and evaluation of the impact on institutional costs and patient adherence to screening and surveillance colonoscopy deserve to be considered.