The diagnostic and therapeutic roles of colonoscopy: a review

Design and Evaluation of a Novel Haptic Interface for Endoscopic Simulation

Inspection of the colon with an endoscope for early signs of cancer (colonoscopy) has become an extremely widespread procedure, since early treatment radically improves the outlook of patients. The procedure requires a close coordination between the sense of touch and vision to navigate the endoscope along the colon. This raises the need to develop efficient training methods for physicians. Training simulators based on virtual reality, where realistic graphics are combined with a mechatronic system providing haptic feedback, are alternative to traditional training methods. To provide physicians with realistic haptic sensations of an endoscopic procedure, we have designed a haptic interface, instrumented a clinical endoscope and combined them with a simulation software for colonoscopy. In this contribution, we present the mechatronic components of the simulator. The haptic interface is able to generate high forces using the combination of electrical motors and brakes in a compact design. Experiments were performed to determine the characteristics of the device. A model-based control has been implemented and the results show that the control successfully compensates for the device nonlinearities, such as friction. The proposed haptic interface, together with the virtual reality, form a highly realistic training simulator for endoscopic surgeons, applicable not only to colonoscopy, but also to similar interventions.

Instrumentation of a clinical colonoscope for surgical simulation

This paper describes the instrumentation of a clinical colonoscope needed for a novel colonoscopy simulation framework. The simulator consists of a compact and portable haptic interface and a virtual reality environment to provide real-time visualization. The proposed instrumentation enables tracking different functions of the colonoscope while keeping the ergonomics unchanged.

The role of intraoperative carbon dioxide insufflating upper gastrointestinal endoscopy during laparoscopic surgery

BACKGROUND

Intraoperative endoscopy (IOE) is a useful adjunct during laparoscopic gastrointestinal (GI) surgery. However, one potential hazard of IOE is a prolonged bowel distension due to insufflated air, which may cause obstructed surgical exposure and increased postoperative abdominal pain. Recently, carbon dioxide (CO(2)), with its rapid absorptive nature, has been proven effective to minimize prolonged bowel distension in ambulatory/intraoperative colonoscopy. The objectives were to assess the feasibility, safety, and efficacy of CO(2)-insufflating upper GI IOE during laparoscopic surgery.

METHODS

A historical comparison study was performed on the initial ten consecutive patients who underwent CO(2)-insufflating upper GI IOE (CO(2)-IOE) during laparoscopic surgery. The control group consisted of the past 12 consecutive patients who underwent conventional air-insufflating upper GI IOE (air-IOE) during laparoscopic surgery. The following parameters were compared between the two groups: (1) patient demographics; (2) feasibility (% completion of IOE); (3) safety (complications related to IOE, impacts on cardiopulmonary status, including systemic blood pressure, heart rate, and end-tidal CO(2)); (4) efficacy (postoperative residual intestinal gas, time to resume oral intake, and bowel movement). The amounts of post-IOE residual intestinal gas were evaluated and classified on the immediate postoperative abdominal radiographs in a blinded manner.

RESULTS

Patient demographics were comparable between the two groups. IOE was completed in both groups without complications. Adverse effects on cardiopulmonary status were not observed during simultaneous intraperitoneal and intraluminal CO(2) insufflation. In the air-IOE group, one patient was converted to open surgery because of inadequate surgical exposure from prolonged distension of the downstream bowel. The patients in the CO(2)-IOE group had significantly lower grade of postoperative bowel distension than the control group. Postoperative oral intake was resumed earlier in the CO(2)-IOE group.

CONCLUSION

CO(2)-insufflating upper GI IOE during laparoscopic surgery is feasible, safe, and has a practical advantage in minimizing post-IOE bowel distension compared with conventional air-insufflating upper GI IOE.

Commonly used preparations for colonoscopy: efficacy, tolerability, and safety--a Canadian Association of Gastroenterology position paper

INTRODUCTION

The increased demand for colonoscopy, coupled with the introduction of new bowel cleansing preparations and recent caution advisories in Canada, has prompted a review of bowel preparations by the Canadian Association of Gastroenterology.

METHODS

The present review was conducted by the Clinical Affairs group of committees including the endoscopy, hepatobiliary/transplant, liaison, pediatrics, practice affairs and regional representation committees, along with the assistance of Canadian experts in the field. An effort was made to systematically assess randomized prospective trials evaluating commonly used bowel cleansing preparations in Canada.

RESULTS

Polyethylene glycol (PEG)-; sodium phosphate (NaP)-; magnesium citrate (Mg-citrate)-; and sodium picosulphate, citric acid and magnesium oxide (PSMC)-containing preparations were reviewed. Regimens of PEG 2 L with bisacodyl (10 mg to 20 mg) or Mg-citrate (296 mL) are as effective as standard PEG 4 L regimens, but are better tolerated. NaP preparations appear more effective and better tolerated than standard PEG solutions. PSMC has good efficacy and tolerability but head-to-head trials with NaP solutions remain few, and conclusions equivocal. Adequate hydration during preparation and up to the time of colonoscopy is critical in minimizing side effects and improving bowel cleansing in patients receiving NaP and PSMC preparations. All preparations may cause adverse events, including rare, serious outcomes. NaP should not be used in patients with cardiac or renal dysfunction (PEG solution is preferable in these patients), bowel obstruction or ascites, and caution should be exercised when used in patients with pre-existing electrolyte disturbances, those taking medications that may affect electrolyte levels and elderly or debilitated patients. Health Canada's recommended NaP dosing for most patients is two 45 mL doses 24 h apart. However, both safety and efficacy data on this dosing schedule are lacking. Many members of the Canadian Association of Gastroenterology expert panel administer both doses within 24 h, as studied in clinical trials, after careful one-on-one discussion of risks and benefits in carefully selected patients. Safety data on PSMC and combination preparations in North America are limited and clinicians are encouraged to keep abreast of developments in this area.

CONCLUSIONS

All four preparations reviewed provided effective bowel cleansing for colonoscopy in the majority of patients, with varying tolerability. Adequate hydration is essential in patients receiving the preparations.

Carbon dioxide insufflation attenuates parietal blood flow obstruction in distended colon

BACKGROUND

Bowel distention after colonoscopy has been considered as a cause of blood flow disturbance. Carbon dioxide (CO2), with its higher absorbability and vasodilating effect, may reduce parietal blood flow disturbance of distended colon when used for intraluminal insufflation instead of air. The purpose of this study was to assess parietal blood flow of the colon distended with intraluminal air/CO2 insufflation.

METHODS

A 5-cm segment of rat colon was insufflated with either air (air group) or CO2 (CO2 group). Two insufflation methods were employed: temporary insufflation up to an intraluminal pressure of 60 mmHg and continuous insufflation at a pressure of 5, 15, and 30 mmHg. Bowel distention and parietal blood flow measured by laser Doppler imaging were evaluated.

RESULTS

For temporary insufflation, bowel distention was prolonged in the air group, whereas it rapidly resolved in the CO2 group. Parietal blood flow decreased in both groups; however, it recovered within 5 min in the CO2 group. For continuous insufflation, under 5 mmHg insufflation, blood flow decreased in the air group, whereas it increased in the CO2 group. Blood flow decreased in both groups under 15 mmHg insufflation; however, it decreased less in the CO2 group. There was a reverse relationship between insufflation pressure and blood flow difference. Inhibition of nitric oxide synthase, ATP-sensitive K+ channel, or heme oxygenase was ineffective against a CO2-induced increase in blood flow.

CONCLUSION

CO2 insufflation preserved parietal blood flow not only by rapid resolution of bowel distention but also by its potential vasodilative effect.

[The importance of rectoscopy and colonoscopy in Internal Medicine]

The endoscopic examination of the large intestine can be considered today a routine examination in internal medicine. Since the introduction of flexible videoendoscopy, evaluating diseases in the distal colon using rectoscopy has become less important. Anoproctoscopy is an obligatory component for a complete colon diagnostic after a flexible ileo-colonoscopy has been performed. Colonoscopy has improved significantly the diagnosis and therapy of diseases in the large intestine since it has been introduced more than 30 years ago. By introducing modern videocolonoscopy in addition to other instruments, there is today a broad spectrum of diagnostic and therapeutic indications available. Specifically, due to its frequency and prognostic relevance, colonoscopy has become the most powerful and important procedure in the early detection and prevention of colon cancer.