The Aer-O-Scope: Proof of Concept of a Pneumatic, Skill-Independent, Self-Propelling, Self-Navigating Colonoscope
2006; Elsevier BV; Volume: 130; Issue: 3 Linguagem: Inglês
10.1053/j.gastro.2005.12.018
ISSN1528-0012
AutoresBoris Vucelić, Douglas K. Rex, Roland Pulanić, Jorge Pfefer, Irena Hrstić, Bernard Levin, Zamir Halpern, Nadir Arber,
Tópico(s)Gastric Cancer Management and Outcomes
ResumoBackground & Aims: Endoscopic screening of the colon with available instruments requires considerable training, is often painful, and carries a risk of perforation. New instrument platforms for endoscopic screening could be useful. The aim of this study was to evaluate the extent of colonic intubation by using a novel self-propelled, self-navigating endoscope (the Aer-O-Scope; GI View Ltd, Ramat Gan, Israel). Methods: Twelve young healthy volunteers underwent complete bowel preparation followed by a nonsedated examination using the novel device. Each examination was followed by a standard colonoscopy for safety evaluation. Cecal intubation was confirmed by endoscopic landmarks and fluoroscopy. Results: In 10 out of 12 subjects (83%) the cecum was successfully reached, whereas in 2 cases the Aer-O-Scope advanced to the hepatic flexure. The time to complete advancement to cecum averaged 14.0 ± 7 minutes, and the driving pressures averaged 34 ± 2.3 milibar. Two subjects requested analgesics during the procedures (in both cases the cecum was reached). Four subjects experienced sweating and a bloating sensation that resolved spontaneously. All subjects were followed up to 48 hours and then for 30 days postprocedure, and no complications were observed. Conclusions: In a preliminary pilot feasibility study of this new instrument, the Aer-O-Scope effectively intubated all or most of the colon. Further clinical studies are warranted. Background & Aims: Endoscopic screening of the colon with available instruments requires considerable training, is often painful, and carries a risk of perforation. New instrument platforms for endoscopic screening could be useful. The aim of this study was to evaluate the extent of colonic intubation by using a novel self-propelled, self-navigating endoscope (the Aer-O-Scope; GI View Ltd, Ramat Gan, Israel). Methods: Twelve young healthy volunteers underwent complete bowel preparation followed by a nonsedated examination using the novel device. Each examination was followed by a standard colonoscopy for safety evaluation. Cecal intubation was confirmed by endoscopic landmarks and fluoroscopy. Results: In 10 out of 12 subjects (83%) the cecum was successfully reached, whereas in 2 cases the Aer-O-Scope advanced to the hepatic flexure. The time to complete advancement to cecum averaged 14.0 ± 7 minutes, and the driving pressures averaged 34 ± 2.3 milibar. Two subjects requested analgesics during the procedures (in both cases the cecum was reached). Four subjects experienced sweating and a bloating sensation that resolved spontaneously. All subjects were followed up to 48 hours and then for 30 days postprocedure, and no complications were observed. Conclusions: In a preliminary pilot feasibility study of this new instrument, the Aer-O-Scope effectively intubated all or most of the colon. Further clinical studies are warranted. The goal of achieving effective prevention of colorectal cancer (CRC) is driven by CRC being a leading cause of cancer death in the western world. More than 945,000 new cases and 492,000 deaths are predicted worldwide in 2005.1Steward B.W. Kleihues P. Colorectal cancer.in: World Cancer Report. IARC Press, Lyon2003: 198-202Google Scholar Most CRCs arise from benign adenomas, the resection of which prevents most CRC.2Winawer S.J. Zauber A.G. Ho M.N. O’Brien M.J. Gottlieb L.S. Sternberg S.S. Waye J.D. Schapiro M. Bond J.H. Panish J.F. et al.Prevention of colorectal cancer by colonoscopic polypectomy. The National Polyp Study Workgroup.N Engl J Med. 1993; 329: 1977-1981Crossref PubMed Scopus (3941) Google Scholar, 3Citarda F. Tomaselli G. Capocaccia R. Barcherini S. Crespi M. Efficacy in standard clinical practice of colonoscopic polypectomy in reducing colorectal cancer incidence.Gut. 2001; 48: 812-815Crossref PubMed Scopus (619) Google Scholar, 4Thiss-Evensen E. Hoff G.S. Sauar J. Langmark F. Majak B.M. Vatn M.H. Population-based surveillance by colonoscopy: effect on the incidence of colorectal cancer. Telemark Polyp Study I.Scand J Gastroenterol. 1999; 34: 414-420Crossref PubMed Scopus (411) Google Scholar Endoscopy of the lower bowel (colonoscopy and sigmoidoscopy) is the most effective and widely used means of screening the colorectum for adenomas. Colonoscopy and sigmoidoscopy are both performed widely by using flexible endoscopes that require considerable training to operate, may produce pain and discomfort during insertion, and carry a risk of colonic perforation.5Rex D.K. Johnson D.A. Lieberman D.A. Burt R.W. Sonnenberg A. Colorectal cancer prevention 2000 screening recommendations of the American college of Gastroenterology.Am J Gastroenterol. 2000; 95: 868-877PubMed Google Scholar, 6Gatto N.M. Frucht H. Sundararajan V. Jacobson J.S. Grann V.R. Neugut A.I. Risk of perforation after colonoscopy and sigmoidoscopy a population-based study.J Natl Cancer Inst. 2003; 95: 230-236Crossref PubMed Scopus (416) Google Scholar, 7Levin T.R. Conell C. Shapiro J.A. Chazan S.G. Nadel M.R. Selby J.V. Complications of screening flexible sigmoidoscopy.Gastroenterology. 2002; 123: 1786-1792Abstract Full Text Full Text PDF PubMed Scopus (88) Google Scholar Screening is the most important strategy in the prevention of CRC. However, despite the shown benefits of screening,8Smith R.A. von Eschenbach A.C. Wender R. Levin B. Byers T. Rothenberger D. et al.ACS Prostate Cancer Advisory Committee, ACS Colorectal Cancer Advisory Committee, ACS Endometrial Cancer Advisory CommitteeAmerican cancer society guidelines for the early detection of cancer update of early detection guidelines for prostate, colorectal and endometrial cancer. Also: update 2001—testing for early lung cancer detection.CA Cancer J Clin. 2001; 51: 38-75Crossref PubMed Scopus (719) Google Scholar, 9From the Centers for Disease Control and Prevention. Trends in screening for colorectal cancer—United States, 1997 and 1999.JAMA. 2001; 185: 1570-1571Google Scholar, 10Winawer S.J. A quarter century of colorectal cancer screening progress and prospects.J Clin Oncol. 2001; 19: 6s-12sPubMed Google Scholar incidence and mortality rates of this common cancer remain high. Mass screening efforts have been compromised by performance limitations and low user rates of the tools currently available. Better screening techniques are needed that combine the features of accuracy, minimal invasiveness, convenience, safety, widespread access, and affordability. Furthermore, the tool must be broadly accepted by the general public, health care providers, and third-party payers.11Anderson W.F. Guyton K.Z. Hiatt R.A. Vernon S.W. Levin B. Hawk E. Colorectal cancer screening for persons at average risk.J Natl Cancer Inst. 2002; 94 (Erratum in: J Natl Cancer Inst 2002;94,1507): 1126-1133Crossref PubMed Scopus (72) Google Scholar The primary advantage of self-advancement is that it avoids the need for a highly skilled operator. Therefore, it could potentially increase endoscopic capacity. Previous attempts at alternative methods for lower bowel endoscopic screening have, as yet, had minimal impact.12Robotic Endoscope and an Autonomous Pipe Robot for Performing Endoscopic Procedures. 2000Google Scholar, 13Manciassi A, Park H Jong, Lee S, Gorini S, Dario P, Park Jong-Oh. Robotic solutions and mechanisms for a semi-autonomous endoscope. Proceedings of the 2002 IEEE/RSJ International Conference on Intelligent Robots and Systems. EPFL, Lausanne, Switzerland, September 30-October 4, 2002.Google Scholar, 14Shike M. Repici A. Cohen L.B. Goldfarb-Albak S. Fireman Z. Major advances in colonoscopic technology the ColonoSight, a pull-power assisted disposable, non fiber-optic colonoscope.Gastrointest Endosc. 2004; 59: AB113Abstract Full Text Full Text PDF Google Scholar In this report, we describe the first human use of a self-propelled, self-navigating, lower-bowel endoscope (the Aer-O-Scope; GI View Ltd, Ramat Gan, Israel). The Aer-O-Scope is composed of a disposable component (Figure 1, Figure 2) and a work station (Figure 3). The disposable unit consists of a rectal introducer, a supply cable, and a scope embedded within a scanning balloon serving as its vehicle. The rectal introducer is a hollow silicon tube (19 mm in diameter) with a silicone balloon attached to its outer surface. The introducer is inserted into the rectum with its outer balloon, and the endoscope and its vehicle balloon are passed through the hollow tube of the introducer. The silicone balloon on the introducer seals the anus to prevent gas leakage. CO2 is insufflated between the 2 inflated balloons, and gas pressure advances the vehicle balloon, endoscope, and a trailing supply cable.Figure 2(A) Optical head protruding from the balloon. (B) It is a complementary metal-oxide semiconductor–based optical head measuring 1.5 × 4 cm.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 3Workstation with disposable Aer-O-Scope. A PC-based workstation with integrated interface for electronic medical record is operated via a control box at the patient’s side. The operator can choose various operation modes of advancement such as with a VCR, ie, forward, backward, pause, and stop. The motion is generated via an algorithm-derived pressure gradient across the balloon. The pressure in front of, inside, and behind the balloon is measured by pressure sensors and is automatically adjusted by a computerized algorithm. The high-resolution data from the digital camera within the capsule are received, processed, and displayed on the PC screen, as well as digitally recorded on a CD.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The supply cable on the endoscope/scanning balloon is a flexible 2.5-m long, 5.5 mm in diameter, polyurethane multiluminal catheter coated with a hydrophilic material that supplies the electro-optical capsule (the scope) and its vehicle balloon with electricity, air, water, and suction. The supply cable extends from the vehicle balloon to an external work station. The device uses 3 automated, independent, pressure regulators (mechanical-, electrical-, and computer-algorithm based) to ensure that a preset maximal colonic pressure of 54 mbar is not exceeded (the working pressure is lower). The pressures in and around the balloon are monitored by electronic sensors and displayed on the screen. The operator can choose to vent the device, thereby reducing pressure completely at any time using the stop key. At the distal tip of the supply cable is a 1.5- × 4-1 cm electro-optical capsule containing a complementary metal-oxide semiconductor–based digital camera embedded within a low-pressure hydrophilic-coated vehicle balloon with a transparent dome containing the optical lenses protruding from the balloon’s front end. White-light emission diodes within the transparent dome provide illumination. The balloon is designed to accommodate to the shape of the colon. Its role is to seal the colon so that a pressure gradient can build across the balloon. The balloon has thin walls (8 μm) and a predetermined maximal diameter. A computer algorithm based on pressure rather than volume allows it to accommodate its shape and size to the shape and diameter of the colon, with the goal of minimal friction with, and minimal pressure on the colonic walls. The user interface is provided by a PC-based workstation with integrated interface for the electronic medical record. The workstation is operated by a control box, which is brought to the patient’s side by way of a flexible sidearm. The workstation is connected to the scope by the disposable supply cable and controls the gas pressure behind and within the vehicle balloon. The pressures in front of, inside, and behind the balloon are measured by pressure sensors and are automatically adjusted by a computerized algorithm. The operator can choose various operation modes including forward, backward, pause, and stop. The motion of the device is generated by the algorithm-derived pressure gradients across the balloon. The high-resolution data from the digital camera within the capsule are received, processed, and displayed on the PC screen, as well as digitally recorded on a CD. The rectal introducer is advanced through the anus into the rectum, and its balloon is inflated. The vehicle (scanning) balloon is pushed through the rectal introducer by feeding the supply cable through the rectal introducer. Then, the vehicle balloon is inflated (Figure 3A, step 1). Finally, the compartment between the rectal introducer’s balloon (stationary balloon) and the vehicle balloon is insufflated by the workstation with CO2 through a distal end opening in the rectal introducer (Figure 3B, step 2). Once CO2 pressure is high enough, the vehicle balloon moves forward through the colon, dragging behind it the supply cable. Pressures within, in front, and behind the vehicle balloon are continuously measured by pressure sensors and transmitted to the workstation. The computer algorithm continuously adjusts the pressure levels in all 3 compartments (within, in front, and behind the balloon). The maximal pressure generated behind the vehicle balloon is set to 40 mbar (normal mode) or 50 mbar (high mode). Once the vehicle balloon reaches the cecum, the reverse mode is activated by pressing a button on the working station. The pressure behind and inside of the balloon is reduced, whereas the colon in front of the balloon is slightly insufflated with CO2, thus creating a pressure gradient in front of the balloon, and the motion is reversed. The pressure maintained in front of the balloon produces distension of the colon needed for viewing (Figure 3C, step 3). The motion of the balloon and imaging head toward the rectum may be facilitated by the operator gently by pulling on the supply cable. Images are displayed in real time on the monitor and are recorded on a CD. Once the procedure is completed, the colon is deflated, the rectal seal is released, and the device is gently removed from the colon. This proof of concept pilot study was designed to evaluate whether this pneumatic, low-pressure advancement technology was safe and effective in healthy subjects. The primary end point was the extent of colonic intubation with the Aer-O-Scope. The secondary endpoint was the safety of the device. After satisfactory completion of preclinical studies in animals, 12 healthy volunteers between the ages of 20 and 43 were enrolled. At the screening visit, demographic data and a medical history were obtained, a complete physical examination (including weight and vital signs measurements) was performed, an electrocardiogram and chest x-ray were done, and concomitant medications were reviewed. Blood and urine samples were obtained for clinical laboratory testing (complete blood count, serum electrolytes, transaminases, albumin, globulin, alkaline phosphatase, bilirubin, urea, creatinine, sodium, potassium, calcium, and urinalysis). Subjects were excluded from the study if they had any known previous gastrointestinal-related symptoms or diseases, previous abdominal surgery, any cardiovascular or pulmonary disorders, cancer, or other life-threatening diseases. Subjects who had participated in any clinical study within the last 30 days, had restricted mobility, were under custodial care or were unable to communicate with the medical staff, were pregnant women, were morbidly obese individuals (body mass index >40), or had a history of drug abuse or alcoholism were excluded from the study as well. The subjects agreed to participate in the study and signed the informed consent before entry in the study. One day before the procedure, eligible subjects underwent a complete bowel preparation with 2 bottles of phosphate soda (45 mL each). An additional Fleet enema (Dexxon, Hadera, Israel) was administered 30–120 minutes before the examination, and an intravenous line was placed in advance. A nonsedated colonic examination using the Aer-O-Scope device was conducted. Each examination was followed by a standard colonoscopy (for a safety evaluation). Cecal intubation was identified by standard anatomical landmarks (ileocecal valve, cecal folds, or appendiceal orifice). X-ray fluoroscopic images confirmed that the cecum had been reached. Both examinations were conducted by an experienced gastroenterologist from Rebro University in Zagreb. The following data were recorded using case report forms: maximal reach of the scope and the duration of unassisted travel, intracolonic pressure, and the frequency and nature of adverse events. All the subjects were followed up via a telephone interview by one of the study physicians (BV, RP, IH) after 24–48 hours and again 30 days postprocedure. The study protocol and the informed consent documents were approved by the Croatian Central Ethics Committee before the commencement of the study (Rebro University Hospital, Zagreb, Croatia). The study was conducted in accordance with the International Conference of Harmonization ICH guidance on Good Clinical Practice Consolidated Guidance and the current version of the Declaration of Helsinki. This was a clinical feasibility study; hence, data analysis is descriptive in nature. Data are reported as mean ± standard deviation. Twelve healthy volunteers (11 men) were enrolled in this study. The mean body mass index was 25.4 ± 3.0. Their ages averaged 30 ± 8 years (range, 20–43 years), and their average weight and height were 86 ± 15 kg and 183 ± 8.5 cm, respectively. In 10 (83%) subjects, the Aer-O-Scope reached the cecum (Figure 4) and in 2 cases the hepatic flexure. In the 2 cases in which the cecum was not reached, the standard colonoscope also could not be passed beyond the hepatic flexure because of a redundant colon (1 case) and pain (1 case). The duration of the procedures averaged 23 minutes (range, 15–34.5 minutes). The time to maximal advancement (n = 12) averaged 16 minutes, whereas the time to cecal intubation (n = 10) averaged 14 minutes. Withdrawal time (n = 12) averaged 3 minutes; however, because visualization was not part of the end point of this study, time was not spent on meticulous visual inspection of the colonic mucosa. The maximal pressure at the back of the device, representing the high driving pressure, throughout the entire Aer-O-Scope examinations averaged 34 ± 2.3 mbar. Two subjects requested analgesics (intravenous 0.1 mg/kg of morphine). In both cases, the cecum was successfully reached. Four subjects experienced some sweating and a bloating sensation that resolved spontaneously within a few minutes. In 4 subjects, the follow-up standard colonoscopy revealed mild local submucosal petechial lesions that were probably caused by friction between the device and the colonic mucosa (Figure 5). These were similar to lesions commonly seen with conventional colonoscopy. All subjects were followed up for 48 hours and 30 days postprocedure without any clinically significant adverse events. In this pilot study, the self-propelling, self-navigating, skill-independent features of the Aer-O-Scope, a new device for colorectal endoscopy, were studied. In a small number of selected subjects who were younger (18–43 years) than screening age, the outcome of reaching the cecum in 83% of the cases was comparable to some reports of colonoscopy.15Cotton P.B. Connor P. McGee D. Jowell P. Nickl N. Schutz S. Leung J. Lee J. Libby E. Colonoscopy practice variation among 69 hospital-based endoscopists.Gastrointest Endosc. 2003; 57: 352-357Abstract Full Text Full Text PDF PubMed Scopus (113) Google Scholar, 16Wexner S.D. Garbus J.E. Singh J.J. SAGES Colonoscopy Study Outcomes GroupA prospective analysis of 13,580 colonoscopies. Reevaluation of credentialing guidelines.Surg Endosc. 2001; 15: 251-261Crossref PubMed Scopus (226) Google Scholar, 17Bowles C.J. Leicester R. Romaya C. Swarbrick E. Williams C.B. Epstein O. A prospective study of colonoscopy practice in the UK today are we adequately prepared for national colorectal cancer screening tomorrow?.Gut. 2004; 53: 277-283Crossref PubMed Scopus (531) Google Scholar, 18Ball E.J. Osbourne J. Jowett S. Pellen M. Welfare M.R. Quality improvement programme to achieve acceptable colonoscopy completion rates prospective before and after study.BMJ. 2004; 329: 665-667Crossref PubMed Scopus (65) Google Scholar It is unknown how the device might perform in symptomatic or older individuals who would be more likely to have diverticular disease and prior pelvic surgery. Immediate follow-up examinations performed by using a conventional colonoscope showed only minimal mucosal trauma from the Aer-O-Scope. No complications occurred. The pressures recorded were significantly lower than those reported during standard colonoscopy19Sumananc K. Zeralley I. Fox B.M. Rawlinson J. Salena B. Marshall J.K. Stevenson G.W. Hunt R.H. Minimizing postcolonoscopy abdominal pain by using CO(2) insufflations a prospective, randomized, double blind, controlled trial evaluating a new commercially available CO2 delivery system.Gastrointest Endosc. 2002; 56: 190-194PubMed Google Scholar, 20Church J. Delaney C. Randomized, controlled trial of carbon dioxide insufflations during colonoscopy.Dis Colon Rectum. 2003; 46: 322-326Crossref PubMed Scopus (117) Google Scholar, 21Woltjen J.A. A retrospective analysis of cecal barotrauma caused by colonoscope air flow and pressure.Gastrointest Endosc. 2005; 61: 37-45Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar and comparable to those reported during virtual colonoscopy.22Rogalla P. Meiri N. Ruckert J.C. Hamm B. Colonscopy using multislice CT.Eur J Radiol. 2000; 36: 81-85Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar The potential advantages for this technology include the need for only minimal training of the operator, reduced pain compared with conventional lower bowel endoscopes which may alleviate the need for sedation, and the potential for reduced risk of mechanical perforation because of the measured low-level forces used during insertion. The need for minimal training to learn insertion and the possibility of patients needing no or little sedation might translate into increased throughput or increased CRC-screening capacity.23Seeff L.C. Manninen D.L. Dong F.B. Chattopadhyay S.K. Nadel M.R. Tangka F.K. Molinari N.A. Is there endoscopic capacity to provide colorectal cancer screening to the unscreened population in the United States?.Gastroenterology. 2004; 127: 1661-1669Abstract Full Text Full Text PDF PubMed Scopus (248) Google Scholar Interpretation of the images will require prior endoscopic expertise or more advanced training. Looping occurs in 91% of all standard colonoscopies, particularly in the sigmoid colon, and is a major cause of pain, especially in women.24Shah S.G. Brooker J.C. Thapar C. Williams C.B. Saunders B.P. Patient pain during colonoscopy an analysis using real-time magnetic endoscopic imaging.Endoscopy. 2002; 34: 435-440Crossref PubMed Scopus (114) Google Scholar Straightening of bowel loops and presumed overinsufflation are additional causes of pain.25Shah S.G. Saunders B.P. Brooker J.C. Williams C.B. Magnetic imaging of colonoscopy an audit of looping, accuracy and ancillary maneuvers.Gastrointest Endosc. 2000; 52: 1-8Abstract Full Text Full Text PDF PubMed Scopus (119) Google Scholar Because the Aer-O-Scope is not pushed into the colon like a standard colonoscope but rather advances itself while assuming the shape of the colon, it is likely less traumatic to the colonic wall and is expected to cause less pain. Indeed, no serious adverse events occurred during the Aer-O-Scope procedures nor were any unexpected adverse events reported up to 30 days after the procedures. A larger clinical experience will be needed to understand the safety of the device. The Aer-O-Scope is intended to be used for screening and diagnostic purposes and thus does not have a working channel for accessories. The device cannot replace therapeutic colonoscopy. The results reported herein warrant additional studies of the Aer-O-Scope and suggest a potential role for this device in CRC screening. Continuing Medical Education Exams 2: March 2006: Biofeedback Is Superior to Laxatives for Normal Transit Constipation due to Pelvic Floor DyssynergiaGastroenterologyVol. 130Issue 3Preview Full-Text PDF Continuing Medical Education Exams 1: March 2006GastroenterologyVol. 130Issue 3Preview Full-Text PDF Continuing Medical Education Exams 4: March 2006: Predicting Cirrhosis Risk Based on the Level of Circulating Hepatitis B Viral LoadGastroenterologyVol. 130Issue 3Preview Full-Text PDF This Month in GastroenterologyGastroenterologyVol. 130Issue 3PreviewThere are two general approaches to the treatment of Crohn’s disease, the first involving a step-up approach where the level of anti-inflammatory therapy is sequentially advanced to match the anatomic and clinical severity of disease; and the second, a top-down approach where intensive therapy (immunosuppressants and/or biologics) is used early in order to maintain a good quality of life and prevent potential irreversible consequences of the disease. Although the former is most frequently practiced, the choice of therapeutic approach would be benefited by knowing clinical criteria present at the time of diagnosis, which would be predictive of natural history. Full-Text PDF Proof of Concept of a New ColonoscopeGastroenterologyVol. 130Issue 7PreviewI read with some interest the article “The Aer-O-Scope: Proof of Concept of a Pneumatic, Skill Independent, Self-Propelling, Self-Navigating Colonoscpe” (2006:130:672–677). The device is clearly quite neat, and a triumph of technology. There was nary a bad word about it in the entire article. However, I have several questions for the authors. The first would be whether any of the authors have a financial stake in the company GI View LTD, either as shareholders or as paid members of the firm’s scientific board. Full-Text PDF
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