Mechanical analysis of insertion problems and pain during colonoscopy: why highly skill-dependent colonoscopy routines are necessary in the first place... and how they may be avoided

A Framework for the Evaluation of Human Machine Interfaces of Robot-Assisted Colonoscopy

The Human Machine Interface (HMI) of intraluminal robots has a crucial impact on the clinician's performance. It increases or decreases the difficulty of the tasks, and is connected to the users' physical and mental stress.

OBJECTIVE

This article presents a framework to compare and evaluate different HMIs for robotic colonoscopy, with the objective of identifying the optimal HMI that minimises the clinician's effort and maximises the clinical outcomes.

METHODS

The framework comprises a 1) a virtual simulator (clinically validated), 2) wearable sensors measuring the cognitive load, 3) a data collection unit of metrics correlated to the clinical performance, and 4) questionnaires exploring the users' impressions and perceived stress. The framework was tested with 42 clinicians investigating the optimal device for tele-operated control of robotic colonoscopes. Two control devices were selected and compared: a haptic serial-kinematic device and a standard videogame joypad.

RESULTS

The haptic device was preferred by the endoscopists, but the joypad enabled better clinical performance and reduced cognitive and physical load.

CONCLUSION

The framework can be used to evaluate different aspects of a HMI, both hardware and software, and determine the optimal HMI that can reduce the burden on clinicians while improving the clinical outcome.

SIGNIFICANCE

The findings of this study, and of future studies performed with this framework, can inform the design and development of HMIs for intraluminal robots, leading to improved clinical performance, reduced physical and mental stress for clinicians, and ultimately better patient outcomes.

Successful Intubation Using a Cap-Assisted Colonoscope for Endoscopic Retrograde Cholangiopancreatography in Patients Undergoing Roux-en-Y Reconstruction

Endoscopic retrograde cholangiopancreatography (ERCP) is challenging in patients undergoing Roux-en-Y (REY) reconstruction; although balloon-assisted enteroscopy is the first-line treatment, it is not always available considering equipment and expertise. We aimed to evaluate the feasibility of using a cap-assisted colonoscope as the primary approach for ERCP in REY reconstruction. We included 47 patients with REY who underwent ERCP using a cap-assisted colonoscope between January 2017 and February 2022. The primary outcome was intubation success for ERCP using a cap-assisted colonoscope during REY reconstruction. The secondary outcomes were cannulation success, procedure-related adverse events, and variables affecting successful intubation. Comparing side-to-side jejunojejunostomy (SS-JJ) and side-to-end jejunojejunostomy (SE-JJ) groups, the intubation success rate using a cap-assisted colonoscope in the SS-JJ group was higher than that in the SE-JJ group (34 of 38 (89.5%) vs. 1 of 9 (11.1%), p < 0.001). Successful intubation was achieved in 37 (97.4%) and 8 (88.9%) patients in the SS-JJ and SE-JJ groups, respectively, after applying the rescue technique using a balloon-assisted enteroscope for failed ERCP using only a colonoscope. No perforation occurred. Multivariable analysis showed that SS-JJ was a predictive factor for successful intubation (odds ratio [95% confidence interval] = 37.06 [3.91-925.56], p = 0.005). Usage of a cap-assisted colonoscope can be crucial for ERCP in patients undergoing REY reconstruction. Anatomically, SS-JJ can facilitate easy and accurate identification of the afferent limb and a highly successful ERCP using a cap-assisted colonoscope.

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.

Follow-The-Leader Mechanisms in Medical Devices: A Review on Scientific and Patent Literature

Conventional medical instruments are not capable of passing through tortuous anatomy as required for natural orifice transluminal endoscopic surgery due to their rigid shaft designs. Nevertheless, developments in minimally invasive surgery are pushing medical devices to become more dexterous. Amongst devices with controllable flexibility, so-called Follow-The-Leader (FTL) devices possess motion capabilities to pass through confined spaces without interacting with anatomical structures. The goal of this literature study is to provide a comprehensive overview of medical devices with FTL motion. A scientific and patent literature search was performed in five databases (Scopus, PubMed, Web of Science, IEEExplore, Espacenet). Keywords were used to isolate FTL behavior in devices with medical applications. Ultimately, 35 unique devices were reviewed and categorized. Devices were allocated according to their design strategies to obtain the three fundamental sub-functions of FTL motion: steering, (controlling the leader/end-effector orientation), propagation, (advancing the device along a specific path), and conservation (memorizing the shape of the path taken by the device). A comparative analysis of the devices was carried out, showing the commonly used design choices for each sub-function and the different combinations. The advantages and disadvantages of the design aspects and an overview of their performance were provided. Devices that were initially assessed as ineligible were considered in a possible medical context or presented with FTL potential, broadening the classification. This review could aid in the development of a new generation of FTL devices by providing a comprehensive overview of the current solutions and stimulating the search for new ones.

Modeling Haptic Interactions in Endoscopic Submucosal Dissection (ESD)

The ability to provide realistic haptic feedback is indispensable for virtual-reality (VR) based endoscopic colorectal surgery simulators. Despite its importance, force feedback is commonly simulated by simplified approximations with parameters manually tuned in preliminary evaluations due to the complexity of the dynamics of haptic interaction in colonoscopy interventions. Endoscopic submucosal dissection (ESD) is a particularly challenging intervention that requires advanced manual skills for endoscopic control. This work proposes a mechanical impedance model for haptic interactions in ESD formulated via an experimental methodology applied to endoscopic colorectal interventions in general. The developed model is shown to capture the variations in the interaction force during two operations performed at distinct locations on a porcine sample. Salient cues in the recorded haptic interaction data are presented, and changes in the impedance characteristics of the tool-tissue interaction between the steps of the operation are analyzed.

The effectiveness of using an abdominal binder during colonoscopy: a randomized, double-blind, sham-controlled trial

BACKGROUND

Prolongation of cecal intubation time (CIT) directly affects the comfort of the patient and the colonoscopist. In this study, the effectiveness of using an abdominal binder (AB) during colonoscopy on procedure time and colonoscopy outcomes was investigated.

METHODS

We conducted a parallel randomized double-blind sham-device-controlled study of patients who underwent elective outpatient colonoscopy between 1 May 2020, and 31 August 2020. Participants were randomly assigned to AB (n = 173) and sham binder (SB) (n = 173) groups. The primary outcome was CIT. Secondary outcomes were the need for auxiliary maneuvers, the cecum intubation length (CIL) of the colonoscope, visual analog scale (VAS) score, narcotic analgesic dose, and colonoscopy results. Moreover, subgroup analysis was performed in terms of age and obesity indices.

RESULTS

A total of 346 patients were enrolled in the study. The mean CIT was similar between groups (AB group 240 secs, control group 250 secs, p > .05). Manual pressure requirement was less in the AB group (27 vs. 36%, p = .069). VAS score and the need for extra narcotic analgesic drugs were prominently lower in the AB group (p < .001, p = .016, respectively). In the subgroup analyses, in participants at the age of <60 and waist-to-height ratio (WHtR) ≥0.5, manual pressure requirements were significantly shorter in the AB group (p = .017, p = .032, respectively).

CONCLUSION

AB use in selected patients may be advantageous during colonoscopy because it reduces the need for analgesics and post-procedure pain, and reduces the need for auxiliary maneuvers in relatively young and obese patients.

Endorobots for Colonoscopy: Design Challenges and Available Technologies

Colorectal cancer (CRC) is the second most common cause of cancer death worldwide, after lung cancer (Sung et al., 2021). Early stage detection is key to increase the survival rate. Colonoscopy remains to be the gold standard procedure due to its dual capability to optically inspect the entire colonic mucosa and to perform interventional procedures at the same time. However, this causes pain and discomfort, whereby it requires sedation or anaesthesia of the patient. It is a difficult procedure to perform that can cause damage to the colonic wall in some cases. Development of new technologies aims to overcome the current limitations on colonoscopy by using advancements in endorobotics research. The design of these advanced medical devices is challenging because of the limited space of the lumen, the contorted shape, and the long tract of the large bowel. The force applied to the colonic wall needs to be controlled to avoid collateral effects such as injuries to the colonic mucosa and pain during the procedure. This article discusses the current challenges in the colonoscopy procedure, the available locomotion technologies for endorobots used in colonoscopy at a prototype level and the commercial products available.

Colonic displacement as a marker of endoscopic skill: development of a novel tool for endoscopy training

BACKGROUND

Colonoscopy is a technically challenging procedure. The colonoscope is prone to forming loops in the colon, which can lead patient discomfort and even perforation. We hypothesized that expert endoscopists use techniques to avoid loop formation, identify and straighten loops earlier, and thus exert less force.

METHODS

Using a commercially available physical colon simulator model (Kyoto Kagaku), electromagnetic tracking markers (NDI Medical) were placed along the mobile segments of the colon (sigmoid, transverse) to measure the degree of displacement of the colon as the scope was advanced to the cecum. The colon model was set for each participant to simulate a redundant alpha loop in the sigmoid colon. Gastroenterology and surgical trainees and attendings were assessed. Demographic data were collected for each participant.

RESULTS

Seventy-five participants were enrolled in the study. There were 17 (22.7%) attending physicians, and 58 (77.3%) trainees. Attending physicians advanced the scope to the cecum faster. The mean time required for procedure completion was 360.5 s compared to 178.4 s for the trainee and attending groups respectively (mean difference: 182.1 s, 95% CI: 93.0, 269.7; p = 0.0002). Attending physicians exerted significantly lower mean colonic displacement than trainees. The mean colonic displacement was 79.8 mm for the trainee group and 57.9 mm for the attending group (mean difference: 21.9 mm, 95% CI: 2.6, 41.2; p = 0.04). Those who used torque steering caused lower maximum colonic displacement than those who used knob steering.

CONCLUSION

Attending physicians advance the scope during colonoscopy in a manner that results in significantly less colonic displacement than resident trainees. Although prior studies have shown a difference in force application between endoscopists and inexperienced students, ours is the first to differentiate across varying degrees of endoscopic skill. Future studies will define metrics for incorporation into endoscopic training curricula, focusing on techniques that encourage safety and comfort for patients.

EXPERIMENTAL ASSESSMENT OF INTACT COLON DEFORMATION UNDER LOCAL FORCES APPLIED BY MAGNETIC CAPSULE ENDOSCOPES

Magnetically guided capsule endoscopy is a promising technology for clinical application. A platform that simulates the magnetic capsule endoscope system is built to study the deformation process of the colon when its lumen suffers local forces. Force-displacement curves of the porcine large intestine under various experiment conditions, including different loading positions (haustra or taeniae coli), loading directions, colon inner pressures and specimen lengths, were measured to analyze the mechanical behavior of the intact large intestine during interactions with magnetic capsule endoscopes. In the practical application of the magnetic capsule endoscope, these data are imperative to optimize the control scheme and reduce operation risks. Based on our experiments, the taeniae coli of the intact large intestine show higher linear stiffness than the haustra, and inflation reduces the linear stiffness of the colon. Magnetic capsule with small edge radii can more easily damage or even perforate the colon. Based on our test results, we suggest that the force applied to the colon should be limited to below 17[Formula: see text]N when the capsule is actuated forward along the colon and limited to below 10[Formula: see text]N when the capsule is vertical to the colon during lesion screening.

Colorectal cancer prevention by a CLEAR principles-based colonoscopy protocol: an observational study

BACKGROUND AND AIMS

Colorectal cancer (CRC) prevention by colonoscopy has been lower than expected. We studied CRC prevention outcomes of a colonoscopy protocol based on Clean the colon, Look Everywhere, and complete Abnormality Removal (CLEAR) principles.

METHODS

This observational follow-up study studied patients provided screening colonoscopy at a free-standing private ambulatory surgery center in South Carolina by 80 endoscopists from October 2001 to December 2014, followed through December 2015. The colonoscopy protocol, optimized for polyp clearance, featured in-person bowel preparation instructions reinforced by phone, polyp search and removal throughout insertion and gradual withdrawal with circumferential tip movements, and a team approach using all personnel present to maximize polyp detection, patient safety, and clear-margin polypectomy including requesting repeat inspection or additional tissue removal. Outcome measures were postscreening lifetime CRC risk relative to Surveillance Epidemiology and End Results (SEER)-18 and interval cancer rate (postcolonoscopy CRCs among cancer-free patients at screening).

RESULTS

Of 25,862 patients (mean age, 58.1 years; 52% black; 205,522 person-years of observation), 159 had CRC at screening and 67 patients developed interval CRC. The interval CRC rate was 3.34 per 10,000 person-years of observation, 5.79 and 2.24 among patients with and without adenomas, respectively. The rate was similar among older patients (mean age 68.5 years at screening) and with prolonged follow-up. Postscreening lifetime CRC risk was 1.6% (bootstrap 95% confidence interval, 1.3%-1.8%) versus 4.7% in SEER-18, 67% lower. Subgroups with mean screening ages of 50 and 68.5 years showed risk reductions of 80% and 72%, respectively. The adverse event rate was less than usually reported rates: perforation 2.6 per 10,000, bleeding with hospitalization 2.4 per 10,000, and no deaths.

CONCLUSIONS

A colonoscopy protocol optimized for polyp clearance prevented 67% of CRC compared with a SEER-18 population given ongoing population screening.

How much force is required to perforate a colon during colonoscopy? An experimental study

INTRODUCTION

Colonoscopy is a commonly-performed procedure to diagnose pathology of the large intestine. Perforation of the colon is a rare but feared complication. It is currently unclear how much force is actually required to cause such injury nor how this is altered in certain diseases. Our aim was to analyze the forces required to perforate the colon in experiments using porcine tissues.

METHODS

Using 3D printing technology, models of two commercially available colonoscope heads were printed under three configurations: straight (I), 90°- bent (L) and fully bent (U). Samples of porcine colon were assessed with the models and configurations under perpendicular and angular load application and these data compared to the maximum force typically exerted by experienced colonoscopists.

RESULTS

The force required for perforation was significantly lower for the I compared to the L of the larger colonoscope head configuration under angular loading (14.1 vs. 46.5 N). Similar differences were found for linear stiffness when loaded (I vs. L small when loaded perpendicular: 0.8 vs. 2.4 N/mm, I vs. L large when loaded angled 0.7 vs. 2.1 N/mm). The mode and site of failure varied significantly between the scopes, with delamination of the mucosa/submucosa below the sample (96%) for the I, blunt mucosa/submucosa/muscularis failure adjacent to the loading site (77%) for the L, and failure of all colon layers lateral to the loading site (59%) for the U configuration, respectively. Perpendicular and angulated loading resulted in similar load-deformation values. Maximum forces typically exerted by colonoscopists averaged 13.9-27.9 N, depending on the colonoscope model and head configuration.

DISCUSSION

The force required for colon perforation varies depending on the type mode of loading and is likely lower than the force an experienced colonoscopist would exert in daily practice. There is a real risk of perforation, especially when the end of the scope is advancing directly into the colonic wall. The given experimental setup allowed to obtain reliable data of the colon in a standardized scenario, forming the basis for further experiments.

Numerical evaluation of the efficacy of small-caliber colonoscopes in reducing patient pain during a colonoscopy

Patient pain caused by a colonoscope is one of the main complications in completing a colonoscopy. Currently, randomized controlled trial (RCT) is one of the most used methods to evaluate the efficacy of small-caliber (SC) colonoscopes in reducing patient pain during a colonoscopy, compared with a standard colonoscope (SDC). However, many disturbing factors, including endoscopists' skills, characteristics of patients and new technical features of the colonoscope (passive bending and high force transmission shaft), limit the reliability and generalizability of each finding in current RCTs. This paper focuses on modeling the insertion of colonoscopes within colon models using an explicit finite element method (FEM). Such a numerical model could overcome the limitations in RCTs. At the same time, it is expected to evaluate the efficacy of the small-caliber colonoscopes in reducing patient pain during a colonoscopy, while considering the effects of patient characteristics, including age, region and gender. The simulation results in this work showed that: compared with the SDC, a SC colonoscope may be more helpful in reducing discomfort for older patients, patients with smaller colon diameters and females.

Serpentine locomotion through elastic energy release

A model for serpentine locomotion is derived from a novel perspective based on concepts from configurational mechanics. The motion is realized through the release of the elastic energy of a deformable rod, sliding inside a frictionless channel, which represents a snake moving against lateral restraints. A new formulation is presented, correcting previous results and including situations never analysed so far, as in the cases when the serpent's body lies only partially inside the restraining channel or when the body has a muscle relaxation localized in a small zone. Micromechanical considerations show that propulsion is the result of reactions tangential to the frictionless constraint and acting on the snake's body, a counter-intuitive feature in mechanics. It is also experimentally demonstrated that the propulsive force driving serpentine motion can be directly measured on a designed apparatus in which flexible bars sweep a frictionless channel. Experiments fully confirm the theoretical modelling, so that the presented results open the way to exploration of effects, such as variability in the bending stiffness or channel geometry or friction, on the propulsive force of snake models made up of elastic rods.

Endoscope-connected water pump with high flow rates improves the unsedated colonoscopy performance by water immersion method

Objectives

The aim of this study was to determine if different water pump flow rates influence the insertion time of water immersion method in unsedated patients. We tested the hypothesis that high flow rate (HFR) is more effective than low flow rate (LFR) in facilitating insertion. Clinical registration number: NCT01869296.

Methods

Consecutive symptomatic patients without prior abdominal surgery were consented and enrolled. They were randomized to an HFR (10.4 mL/s) or LFR (1.7 mL/s) group. The patients were not informed about the flow rate of the water pump (single blinded). Patients underwent unsedated colonoscopy examination with standard colonoscope. Demographic and procedural parameters were recorded. Data were analyzed with Student’s t-test or Chi-square test as appropriate.

Results

A total of 132 patients (66 in HFR and 66 in LFR group) were recruited. The HFR group showed significantly shorter cecal intubation time (12.5±6.2 min in HFR vs 16.3±7.3 min in LFR, p=0.004), shorter time to pass rectosigmoid (3.6±2.2 min in HFR vs 6.2±4.6 min in LFR, p<0.001), and lower pain score (4.2±2.8 in HFR vs 5.3±2.6 in LFR, p=0.024). The cecal intubation rate was not significantly different (87.9% in HFR vs 80.3% in LFR, p=0.34), and 29 (14 in HFR and 15 in LFR) patients with signs of colon redundancy were successfully intubated to the cecum after repeated loop reduction and position changes.

Conclusion

Compared to LFR, HFR of the water infusion pump significantly reduced colonoscopy insertion time and pain score in unsedated patients. Significantly shorter time to pass the rectosigmoid appeared to play a contributory role.

Safety of Propofol Used as a Rescue Agent During Colonoscopy

GOAL

The goal of this study was to evaluate the safety of propofol when used by gastroenterologists in patients who have an inadequate response to standard sedation (narcotics and benzodiazepines).

BACKGROUND

Many patients fail to achieve adequate sedation from narcotics and benzodiazepines during colonoscopy. The administration of propofol for colonoscopy is increasing, although its use by gastroenterologists is controversial.

STUDY

We performed a retrospective review of our hospital's colonoscopy records from January 2006 to December 2009 to identify 403 subjects undergoing screening colonoscopies who required propofol (20 to 30 mg every 3 min as needed) because of inadequate response to standard sedation. We also randomly selected 403 controls undergoing screening colonoscopies from the same time period that only required standard sedation. The incidence of adverse effects was then compared.

RESULTS

There were no major adverse events in either group. The rates of minor adverse events in the propofol and control group were 0.02 and 0.01, respectively (P=0.56). Adverse effects in the propofol group included: transient hypotension (n=1), nausea/vomiting (n=3), agitation (n=2), and rash (n=1). Adverse effects seen with standard sedation included: transient hypotension (n=2), nausea/vomiting (n=1), and oversedation (n=2). Patients who received propofol were more likely to be younger, had a history of illicit drug use, and a longer procedure time (P<0.05).

CONCLUSIONS

Adjunctive propofol administered by gastroenterologist for conscious sedation was not associated with increased incidence of adverse events. It may be of value in patients who do not respond to conventional sedation.

A hydraulically driven colonoscope

BACKGROUND

Conventional colonoscopy requires a high degree of operator skill and is often painful for the patient. We present a preliminary feasibility study of an alternative approach where a self-propelled colonoscope is hydraulically driven through the colon.

METHODS

A hydraulic colonoscope which could be controlled manually or automatically was developed and assessed in a test bed modelled on the anatomy of the human colon. A conventional colonoscope was used by an experienced colonoscopist in the same test bed for comparison. Pressures and forces on the colon were measured during the test.

RESULTS

The hydraulic colonoscope was able to successfully advance through the test bed in a comparable time to the conventional colonoscope. The hydraulic colonoscope reduces measured loads on artificial mesenteries, but increases intraluminal pressure compared to the colonoscope. Both manual and automatically controlled modes were able to successfully advance the hydraulic colonoscope through the colon. However, the automatic controller mode required lower pressures than manual control, but took longer to reach the caecum.

CONCLUSIONS

The hydraulic colonoscope appears to be a viable device for further development as forces and pressures observed during use are comparable to those used in current clinical practice.

[Risk factors of pain during colonoscopic examination]

OBJECTIVE

To investigate the risk factorsthat predict pain during colonoscopy for decision of sedation or analgesia before the examination.

METHODS

A total of 283 consecutive patients undergoing colonoscopicexamination at Nanfang Hospital between July, 2016 and September, 2016were retrospectively analyzed. The clinical data and visual analogue scale after the examination were analyzed to identify the risk factors for pain during colonoscopy using univariate analysis and multivariate logistic regression. A risk stratification model for predicting pain in colonoscopy was established.

RESULTS

The completion rate of the procedure was significantly lower in patients with a visual analogue scale ≥5 (P<0.000). Univariate analysis showed that female patients, previous abdominal surgery, no previous experience with colonoscopy, complaint of abdominal pain before colonoscopy, insufficient experience of the endoscopists, patient's anticipation of high painlevelbefore examination, and a low body mass index (BMI) were all associated with the experience of pain in colonoscopy (P<0.05). Multivariate logistic regressionanalysis identified BMI index (X₁), level of experience of the endoscopist (A₁, A₂, A₃) and the patient's anticipation of painlevel (X₂) as the risk factors of pain in colonoscopy(P<0.05), and the establishedmodel with the 3 variables was: P=e^Y/(1+e^Y),Y=0.049-0.124×X₁-0.97×X₂+1.713×A₁+0.781×A₂+0.147×A₃, which showed a sensitivity of 70.3% and a specificity of 67.5%for predicting pain in colonoscopy.

CONCLUSION

The patient's anticipation of a high pain level in colonoscopy, insufficient experience of the endoscopist, and a low BMI are the independent risk factors for pain in colonoscopy, and evaluation of these factors can help in the decision-making concerning the use of sedation or analgesia before colonoscopy.