Comparison of the characteristics of the CF-H290I and PCF-Q260JI colonoscopes in non-sedated patients with a history of abdominal or pelvic surgery: a randomized controlled study.

BACKGROUND AND AIM: The purpose of this randomized controlled study was to compare the characteristics of the CF-H290I (high-definition) colonoscope with those of the PCF-Q260JI (high-resolution) colonoscope in non-sedated patients with a history of abdominal or pelvic surgery in an effort to help endoscopists to select more effectively and objectively between the various colonoscopes. METHODS: A total of 397 patients who underwent colonoscopy at the Affiliated Wuxi People's Hospital of Nanjing Medical University, between August 2022 and October 2022 were randomized to a CF-H290I group (n = 198) or a PCF-Q260JI group (n = 199) using a computer-generated allocation method. We compared the adenoma detection rate (ADR), patient satisfaction with the examination, discomfort associated with colonoscopy including abdominal distension and pain, cecal intubation time, and patient willingness to undergo colonoscopy in the future between the CF-H290I and PCF-Q260JI groups. RESULTS: There was no statistically significant difference in the overall ADR between the CF-H290I and PCF-Q260JI groups (81 [40.9%] vs 63 [31.7%], Z = 3.674, P = 0.055). However, the ADRs in the transverse colon and left colon were significantly higher in the CF-H290I group (22 [11.1%] vs 6 [3.0%], Z = 9.588, P = 0.002 and 57 [28.8%] vs 37 [18.6%], Z = 5.212, P = 0.017, respectively). More sessile serrated lesions were detected in the CF-H290I group (52 [26.3] vs 30 [15.1%], Z = 7.579, P = 0.006). Patient satisfaction with colonoscopy was better in the PCF-Q260JI group (8.91 ± 1.09 vs 8.51 ± 1.44, t = -3.158, P < 0.01) with less likelihood of discomfort (23 [11.6%] vs 41 [20.7%], Z = 6.144, P = 0.013), The number of patients willing to undergo colonoscopy in the future was significantly greater in the PCF-Q260JI group (168 [84.4%] vs 149 [75.3%], Z = 5.186, P = 0.023). The cecal intubation time was significantly shorter in the CF-H290I group (256.09 ± 155.70 s vs 315.64 ± 171.64 s, P = 0.004). There were no complications such as perforation or bleeding in either group. CONCLUSION: The CF-H290I and PCF-Q260JI colonoscopes each have advantages when used in patients with a history of abdominal or pelvic surgery. The CF-H290I has higher ADRs in the transverse and left colon whereas the PCF-Q260JI is less painful and better accepted by patients. This study was approved by the Clinical Research Ethics Committee of Wuxi People's Hospital and was registered in the Chinese Clinical Trial Registry (ChiCTR2200063092).

Utility of a Passive Bending Colonoscope for Endoscopic Retrograde Cholangiopancreatography in Patients with Surgically Altered Anatomy.

BACKGROUND AND AIM: The utility of a passive bending colonoscope (PBCS) in ERCP for patients with surgically altered anatomy has not been established. This study compared the outcome of PBCS-ERCP and balloon-assisted enteroscope (BAE)-ERCP. METHODS: This multicenter observational study included 343 patients with surgically altered anatomy who underwent ERCP. Among these, 110 underwent PBCS-ERCP and 233 underwent BAE-ERCP. Propensity score matching was applied, and a final cohort of 210 (105 in each group) with well-balanced backgrounds was analyzed. The primary outcome was the success rate of reaching anastomosis or ampulla of Vater. Secondary endpoints included the cannulation success rate, completion rate, procedure time (to reach, cannulate, complete), and adverse events. RESULTS: The success rate for reaching the target was 91.4% (96/105) with PBCS and 90.5% (95/105) with BAE (odds ratio [95% CI] 1.12, [0.44-2.89], P = 0.809). The mean time required to reach the target was significantly shorter in PBCS: 10.04 min (SD, 9.62) with PBCS versus 18.77 min (SD, 13.21) with BAE (P < 0.001). There were no differences in the success of cannulation or procedure completion, although the required times for cannulation and procedure completion were significantly shorter in PBCS. The incidence of adverse events was significantly higher in BAE (19.0%) than in PBCS (4.8%; P < 0.001). CONCLUSIONS: In patients with surgically altered anatomy, PBCS-ERCP showed promising results with shorter time to reach, cannulate, and a lower incidence of adverse events compared with BAE-ERCP. The success rate of reaching was favorable through PBCS compared with BAE. CLINICAL TRIAL REGISTRATION: UMIN000045546.

Towards Semi-Autonomous Colon Screening Using an Electromagnetically Actuated Soft-Tethered Colonoscope Based on Visual Servo Control.

OBJECTIVE: Conventional colonoscopy using a flexible colonoscope remains two major limitations, including patient discomfort and difficult manipulations for surgeons. Robotic colonoscopes have been developed to conduct colonoscopy in a patient-friendly manner. However, most robotic colonoscopes still maintain nonintuitive and difficult manipulations, which limits their clinical applications. In this paper, we demonstrated visual servo-based semi-autonomous manipulations of an electromagnetic actuated soft-tethered (EAST) colonoscope, which aims to lower difficulties of robotic colonoscope manipulations. METHODS: Kinematic modeling of EAST colonoscope is conducted, with an adaptive visual servo controller established. Template matching method and a lumen and polyp detection model are developed to enable semi-autonomous manipulations, including region-of-interest automatic tracking and autonomous navigation with automatic polyp detection. RESULTS: The EAST colonoscope demonstrates visual servoing with an average convergence time of around 2.5 s and performs disturbance rejection within 3.0 s. Semi-autonomous manipulations were conducted in both a commercialized colonoscopy simulator and an ex-vivo porcine colon to show the efficacy of reducing the user workload compared to manual control. CONCLUSION: The EAST colonoscope can perform visual servoing and semi-autonomous manipulations with the developed methods in both laboratory and ex-vivo environments. SIGNIFICANCE: The proposed solutions and techniques improve the autonomy level of robotic colonoscopes and reduce user workloads, which promotes the development and clinical translation of robotic colonoscopy.

Robotic endoscope with double-balloon and double-bend tube for colonoscopy.

The insertion of conventional colonoscopes can sometimes cause patients to experience pain during the procedure owing to the stretching of the mesentery. In this study, a prototype of a robotic colonoscope with a double-balloon and double-bend tube based on the conventional double-balloon endoscope was developed to simplify insertion and prevent the overstretching of the colon. Both the outer and inner tubes were confirmed to be free from interference from wires and sheaths. Additionally, all functions such as tip bending, inflation and deflation of the balloons, and actuator-driven pulling and pushing of the inner tube were operated properly. During the insertion test, the device could be reached the cecum of a colon model in approximately 442 s when operated by a non-medical operator. In addition, the device did not overstretch the colon model, thereby suggesting that the insertion mechanism can follow the shape of the colon model. As a result, the developed mechanism has the potential to navigate through a highly-bent colon without overstretching.

Laparoscopic versus open surgery for colonoscopic perforation: A systematic review and meta-analysis.

BACKGROUND: The efficacy of laparoscopic surgery (LS) for the treatment of colonoscopic perforation is still controversial. The purpose of this meta-analysis was to evaluate the effectiveness and safety of LS versus open surgery (OS) for colonoscopic perforation. METHODS: All clinical trials that compared laparoscopic with OS for colonoscopic perforation published in English were identified in PubMed, EMBASE, Web of Science, and Cochrane Library searches. A modified scale was used to assess the quality of the literature. We analyzed the age, sex ratio, aim of colonoscopy, history of abdominopelvic surgery, type of procedure, size of perforation, operation time, postoperative fasting time, hospital stay, postoperative complication morbidity, and postoperative mortality. Meta-analyses were performed using weighted mean differences for continuous variables, and odds ratios for dichotomous variables. RESULTS: No eligible randomized trials were identified, but eleven nonrandomized trials were analyzed. In the pooled data of 192 patients who underwent LS and 131 OS, there were no significant differences in age, sex ratio, aim of colonoscopy, history of abdominopelvic surgery, perforation size, and operative time between the groups. LS group had shorter time of hospital stay and postoperative fasting time, less postoperative complication morbidity, but there were no significant difference in postoperative mortality rate between LS group and OS group. CONCLUSIONS: Based on the current meta-analysis, we conclude that LS is a safe and efficacious technique for colonoscopic perforation, with fewer postoperative complications, less hospital mortality, and faster recovery compared with OS.

"Transanal endoscopic microsurgery" with a flexible colonoscope (F-TEM): a new endoscopic treatment for suspicious deep submucosal invasion T1 rectal carcinoma.

BACKGROUND: Endoscopic techniques allow resections of deep submucosal invasion rectal carcinoma, but mostly are facing issues such as costs, follow-up care or size limit. Our aim was to design a new endoscopic technique, which retains the advantages over surgical resections while eliminating the disadvantages mentioned above. PATIENTS AND METHODS: We propose a technique for the resection of the superficial rectal tumours, with highly suspicious deep submucosal invasion. It combines steps of endoscopic submucosal dissection, muscular resection and edge-to-edge suture of the muscular layers, finally performing the equivalent of a "transanal endoscopic microsurgery" with a flexible colonoscope (F-TEM). RESULTS: A 60-year-old patient was referred to our unit, following the discovery of a 15 mm distal rectum adenocarcinoma. The computed tomography and the endoscopic ultrasound examination revealed a T1 tumour, without secondary lesions. Considering that the initial endoscopic evaluation highlighted a depressed central part of the lesion, with several avascular zones, an F-TEM was performed, without severe complication. The histopathological examination revealed negative resection margins, without risk factors for lymph node metastasis, no adjuvant therapy being proposed. CONCLUSION: F-TEM allows endoscopic resection of highly suspicious deep submucosal invasion T1 rectal carcinoma and it proves to be a feasible alternative to surgical resection or other endoscopic treatments as endoscopic submucosal dissection or intermuscular dissection.

A retrospective study of colonoscopic surveillance in the elderly.

BACKGROUND: Aotearoa New Zealand (AoNZ) guidelines suggest surveillance colonoscopy should be carefully considered after age 75. The authors noted a cluster of patients presenting in their 8th and 9th decade of life with a new colorectal cancer (CRC) having previously been declined surveillance colonoscopy. METHODS: A 7-year retrospective analysis was performed of patients who underwent a colonoscopy aged between 71 and 75 years in the period between 2006 and 2012. Kaplan-Meier graphs were created with survival measured from the time of index colonoscopy. Log rank tests were used to determine any difference in survival distribution. Relative risk (RR) was calculated, and 95% confidence intervals (CI) reported. RESULTS: A total of 623 patients met inclusion criteria; 461 (74%) had no indication for surveillance colonoscopy and 162 (26%) had an indication. Of the 162 patients with an indication, 91 (56.2%) underwent surveillance colonoscopies after the age of 75. Twenty-three (3.7%) patients were diagnosed with a new CRC. Eighteen (78.2%) patients diagnosed with a new CRC underwent surgery. The median survival overall was 12.9 years (95% CI 12.2-13.5). This did not differ between patients with (13.1, 95% CI 12.1-14.1) or without (12.6, 95% CI 11.2-14.0) an indication for surveillance. CONCLUSION: This study found one quarter of patients who had a colonoscopy between the ages of 71-75 had an indication for surveillance colonoscopy. Most patients with a new CRC underwent surgery. This study suggests it may be appropriate to update the AoNZ guidelines and consider adopting a risk stratification tool to aid decision making.

Effect of an automated flexible endoscope channel brushing system on improving reprocessing quality: a randomized controlled study.

BACKGROUND: Qualified reprocessing, of which meticulous channel brushing is the most crucial step, is essential for prevention and control of endoscopy-associated infections. However, channel brushing is often omitted in practice. This study aimed to evaluate the effect of an automated flexible endoscope channel brushing system (AECBS) on improving the quality of endoscope reprocessing. METHODS: This prospective, randomized controlled study was conducted between 24 November 2021 and 22 January 2022 at Renmin Hospital of Wuhan University, China. Eligible endoscopes were randomly allocated to the auto group (channels brushed by AECBS) or the manual group (channels brushed manually), with sampling and culturing after high-level disinfection and drying. The primary end point was the proportion of endoscopes with positive cultures. RESULTS: 204 endoscopes in the auto group and 205 in the manual group were analyzed. The proportion of endoscopes with positive cultures was significantly lower in the auto group (15.2 % [95 %CI 10.7 %-21.0 %]) than in the manual group (23.4 % [95 %CI 17.9 %-29.9 %]). CONCLUSIONS: AECBS could effectively reduce bioburden and improve reprocessing quality of gastroscopes and colonoscopes. AECBS has the potential to replace manual brushing and lower the risk of endoscopy-associated infections, providing a new option for the optimization of reprocessing.

Comparison of adenoma detection rate between high-definition colonoscopes with different fields of view: 170 degrees versus 140 degrees.

In newer generation colonoscopes, the field of view (FOV) varies approximately between 170° and 140°, depending on the type of colonoscopy. To the best of our knowledge, no study has investigated whether the visual field difference of the colonoscope affects quality indicators, such as the adenoma detection rate (ADR), without using additional devices to expand the FOV in colonoscopes with the same resolution. This study aimed to investigate the difference in quality indicators, such as ADR, between 170° and 140° FOV in colonoscopes with the same high-definition resolution. We retrospectively analyzed the medical records of patients who underwent screening or surveillance colonoscopy at the Dong-A University Hospital in Busan, South Korea, between March 2021 and February 2022. We calculated the overall ADR ratios for patients who underwent colonoscopy with 140° and 170° FOV. Polyp detection rate (PDR), sessile serrated PDR, and advanced neoplasia detection rate were calculated for each group. Factors associated with adenoma detection were identified using a logistical regression analysis. A total of 1711 patients were included in the study (838 patients in the 170° group and 873 patients in the 140° group). ADR (43.79 vs 41.92%, P = .434) did not significantly differ between the 2 groups. The generational differences were not statistically significant either for PDR (56.44 vs 53.49%, P = .220), sessile serrated PDR (1.19 vs 0.92%, P = .575), or advanced neoplasia detection rate (5.00 vs 4.58%, P = .735). Multivariate regression analysis revealed that, age, male sex, and long withdrawal time were the most significant factors affecting adenoma detection. This study revealed that there were no differences in ADR while employing high definition colonoscopes with a 170° FOV and a 140° FOV.

Comprehensive review of publicly available colonoscopic imaging databases for artificial intelligence research: availability, accessibility, and usability.

BACKGROUND AND AIMS: Publicly available databases containing colonoscopic imaging data are valuable resources for artificial intelligence (AI) research. Currently, little is known regarding the available number and content of these databases. This review aimed to describe the availability, accessibility, and usability of publicly available colonoscopic imaging databases, focusing on polyp detection, polyp characterization, and quality of colonoscopy. METHODS: A systematic literature search was performed in MEDLINE and Embase to identify AI studies describing publicly available colonoscopic imaging databases published after 2010. Second, a targeted search using Google's Dataset Search, Google Search, GitHub, and Figshare was done to identify databases directly. Databases were included if they contained data about polyp detection, polyp characterization, or quality of colonoscopy. To assess accessibility of databases, the following categories were defined: open access, open access with barriers, and regulated access. To assess the potential usability of the included databases, essential details of each database were extracted using a checklist derived from the Checklist for Artificial Intelligence in Medical Imaging. RESULTS: We identified 22 databases with open access, 3 databases with open access with barriers, and 15 databases with regulated access. The 22 open access databases contained 19,463 images and 952 videos. Nineteen of these databases focused on polyp detection, localization, and/or segmentation; 6 on polyp characterization, and 3 on quality of colonoscopy. Only half of these databases have been used by other researcher to develop, train, or benchmark their AI system. Although technical details were in general well reported, important details such as polyp and patient demographics and the annotation process were under-reported in almost all databases. CONCLUSIONS: This review provides greater insight on public availability of colonoscopic imaging databases for AI research. Incomplete reporting of important details limits the ability of researchers to assess the usability of current databases.

Second-generation distal attachment cuff for adenoma detection in screening colonoscopy: a randomized multicenter study.

BACKGROUND AND AIMS: Randomized studies have demonstrated that a distal attachment cap with rubber side arms, the Endocuff Vision (ECV; Olympus America, Center Valley, Pa, USA), increased colonoscopic adenoma detection rate (ADR) in various mixed patient collectives. This is the first study to evaluate its use in a primary colonoscopic screening program. METHODS: Patients over age 55 years undergoing screening colonoscopy in 9 German private offices in Berlin and Hamburg were randomized to either the study group using ECV or the control group using high-definition colonoscopies (standard of care). The main outcome parameter was ADR, whereas secondary outcomes were detection rates of all adenomas per colonoscopy (APCs), of adenoma subgroups, and of hyperplastic polyps. RESULTS: Of 1416 patients (mean age, 61.1 years; 51.8% women), with a median of 41 examinations per examiner (n = 23; interquartile range, 12-81), 700 were examined with ECV and 716 without. Adjusting for the effects of the colonoscopies, ADR was 39.5% (95% confidence interval [CI], 32.6%-46.3%) in the ECV group versus 32.2% (95% CI, 25.9%-38.6%) in the control group, which resulted in an increase of 7.2% (95% CI, 2.3%-12.2%; P = .004). The increase in ADR was mainly because of small polyps, with adjusted ADRs for adenomas <10 mm of 33.3% (95% CI, 26.5%-40.2%) for study patients versus 24.0% (95% CI, 18.2%-29.8%) for control patients (P < .001). APC was also significantly increased (.57 ECV vs .51 control subjects, P = .045). CONCLUSIONS: A distal attachment cap with side arms significantly increased the ADR in patients undergoing primary colonoscopic screening. Because of the correlation of ADR and interval cancer, its use should be encouraged, especially in this setting. (Clinical trial registration number: NCT03442738.).

The colonoscopic vacuum model-simulating biomechanical restrictions to provide a realistic colonoscopy training environment.

INTRODUCTION: Practicing endoscopic procedures is fundamental for the education of clinicians and the benefit of patients. Despite a diverse variety of model types, there is no system simulating anatomical restrictions and variations in a flexible and atraumatic way. Our goal was to develop and validate a new modelling approach for adhesion forces between colon and abdominal wall. METHODS: An inlay for a standard mechanical trainer was designed and 3D printed. Colon specimens were fixed to the inlay along colon ascendens (CA) and colon descendens (CD) by a vacuum. Our system, which we refer to as Colonoscopy Vacuum Model (CoVaMo), was validated with 11 test persons with varying level of expertise. Each performed one colonoscopy and one polypectomy in the CoVaMo and in the Endoscopic Laparoscopic Interdisciplinary Training Entity (ELITE). Achieved adhesion forces, times required to fulfill different tasks endoscopically and a questionnaire, assessing proximity to reality, were recorded. RESULTS: Mean adhesion forces of 37 ± 7 N at the CA and 30 ± 15 N at the CD were achieved. Test subjects considered CoVaMo more realistic than ELITE concerning endoscope handling and the overall anatomy. Participants needed statistically significantly more time to maneuver from anus to flexura sinistra in CoVaMo (377 s ± 244 s) than in ELITE (58 s ± 49 s). CONCLUSION: We developed a training environment enabling anatomically and procedural realistic colonoscopy training requiring participants to handle all endoscope features in parallel. Fixation forces compare to forces needed to tear pig colon off the mesentery. Workflow and inlay can be adapted to any arbitrary ex vivo simulator.

A randomized prospective study comparing single-balloon-assisted colonoscopy and cap-assisted colonoscopy in patients with previous incomplete conventional colonoscopy.

INTRODUCTION: Cecal intubation may be unsuccessful by conventional colonoscopy in some patients. Single-balloon-assisted colonoscopy (SBC) and cap-assisted colonoscopy (CAC) were studied to solve this problem. There was no head-to-head comparison between them. METHODS: We conducted a randomized study from 2018 to 2021 to compare cecal intubation rate of SBC and CAC in patients with previous incomplete conventional colonoscopy. We recruited patients with incomplete conventional colonoscopy in two hospitals in Hong Kong. Patients were randomized into SBC group and CAC group in 1:1 ratio. In the case of failure in cecal intubation by allocated method, alternative modality would be performed as rescue. RESULTS: Forty-four patients were recruited. Cecal intubation rate was superior in SBC group (22/22, 100%) than CAC group (16/22, 72.7%) (P = 0.02). No difference in cecal intubation time, polyp detection rate, and diagnostic gain in area not examined previously. SBC induced less discomfort (modified Gloucester comfort score 2.14 vs 2.63, P = 0.03) with use of comparable amount of midazolam and fentanyl as CAC. For patients failed cecal intubation by CAC, all (n = 6) were rescued successfully by SBC. Body weight, body mass index (BMI), and waist circumference were greater in rescue subgroup. More patients were obese (BMI ≥ 25 kg/m) in rescue subgroup (67% vs 19%). None in rescue subgroup had history of successful cecal intubation by conventional colonoscopy (0% vs 56%, P = 0.046). However, we failed to demonstrate significant association in multivariate analysis owing to small sample size. No adverse event was noted. CONCLUSION: SBC is superior to CAC in cecal intubation in patients with previous incomplete conventional colonoscopy.

The effect of the endoscopic device Endocuff™/Endocuff vision™ on quality standards in colonoscopy: A systematic review and meta-analysis of randomized trials.

AIM: The adenoma detection rate (ADR) is an important quality measure, with a high ADR reflecting high-quality colonoscopy. This systematic review and meta-analysis aimed to assess the effects of Endocuff™/Endocuff Vision™-assisted colonoscopy (EAC) versus standard colonoscopy (SC) on ADR and other clinical, patient and resource-use outcomes. METHOD: MEDLINE, EMBASE, Web of Science, Scopus and the Cochrane Central Register of Controlled Trials were searched for full papers reporting randomized studies comparing EAC with SC. The primary outcome was ADR. Secondary outcomes comprised key polyp/adenoma detection, procedure-related, patient-related and health economic measures. Random effects meta-analyses provided pooled estimates of outcomes [risk ratio (RR) or mean difference (MD), with 95% confidence intervals (CI)]. RESULTS: Twelve parallel-group randomized controlled trials (RCTs) and three crossover RCTs with data on 9140 patients were included. EAC significantly increased the ADR (RR 1.18, 95% CI 1.09-1.29), mean adenomas per procedure (MAP) (MD 0.19, 95% CI 0.06-0.33), polyp detection rate (PDR) (RR 1.20, 95% CI 1.10-1.30) and mean polyps per procedure (MPP) (MD 0.39, 95% CI 0.14-0.63) versus SC. EAC significantly increased segmental PDR versus SC in the sigmoid (RR 2.02, 95% CI 1.64-2.49), transverse (RR 1.63, 95% CI 1.09-2.42), ascending (RR 1.74, 95% CI 1.26-2.41) and caecal segments (RR 1.91, 95% CI 1.29-2.82). Procedure-related variables did not differ between arms. There were insufficient data for meta-analysis of health economic or patient-centred outcomes. CONCLUSIONS: EAC increased ADR, MAP, PDR and MPP versus SC without detrimental effects on procedure measures. Cost-effectiveness and patient experience data are lacking and would be valuable to inform practice recommendations.

Computed tomographic colonography for symptomatic patients: the diminutive polyp dilemma.

BACKGROUND: Computed tomographic colonography (CTC) is sensitive to polyp detection but is considered inaccurate for measuring diminutive polyps (<6 mm), with divergence between CTC and either colonoscopic or histopathological polyp measurements. Reporting diminutive polyps remains debatable. This study aims to compare outcomes of symptomatic patients with diminutive versus borderline polyps on CTC and to thereby examine the potential implication of reporting diminutive polyps. METHODS: A single-centre retrospective study of symptomatic patients who underwent CTC from October 2016 through September 2018 was performed. After excluding CTC demonstrating cancer, no polyps, or polyps >6 mm, cases were categorized as either 'diminutive' (largest polyp <6 mm), or 'borderline' (largest polyp = 6 mm). The outcome measures were progression to endoscopy, surgery, procedure-related morbidity, dysplasia and malignancy. RESULTS: A total of 308 cases (211 diminutive and 97 borderline) were analysed. The groups were similar (P > 0.05) in mean age (73 vs. 74 years), female proportion (57% vs. 49%), endoscopy-related morbidity (6% vs. 7%) and CTC-related morbidity (0 vs. 1%). Most patients (64%) underwent endoscopy, which was more common in the borderline vs. the diminutive group (76% vs. 59%; P = 0.003). Dysplasia was more common in the borderline vs. the diminutive group (69% vs. 48%; P = 0.003). No malignancies were diagnosed, and no patients proceeded to surgery. CONCLUSION: Reporting diminutive polyps on CTC for symptomatic patients frequently leads to endoscopy, which often reveals dysplasia but rarely malignancy. This raises the question of how referring clinicians can best counsel and manage symptomatic patients with diminutive polyps on CTC, by considering the balance between utilitarianism and deontology.