Application of robotic technologies in lower gastrointestinal tract endoscopy: A systematic review

Table 2 Summary of the included studies reviewing robotic lower gastrointestinal endoscopy devices with pneumatic or hydraulic actuation

Ref.	Design and actuation components of evaluated robotic system(s)	Endoscope and/or capsule dimensions	Mode(s) of actuation	Mode(s) of illumination and luminal visualisation	Capabilities evaluated	Degree of robot navigational assistance	Study methodology	Main findings
Vucelic et al[35], 2006 (Israel)	Aer-O-scope (GI View Ltd, Ramat Gan, Israel): Workstation and Disposable unit consisting of a rectal introducer, supply cable, scanning balloon, scope and rectal balloon. The supply cable connects the disposable unit to the workstation with its joystick and is able to transmit air, water and suction	5.5 mm diameter, 2.5 m length	Pneumatic	White LED, 360 panoramic vision system with CMOS camera with a field of view of 57 degrees	Visualisation and safety	Semi-autonomous	In vivo: n = 12 Human, healthy volunteers	CIR is 83%. Median CIT is 14 min with an average procedure duration of 23 min. Analgesia required in 2 patients. 4 patients had submucosal petechial lesions. No complications at 30 d follow up
Gluck et al[36], 2016 (Israel)	Aer-O-scope (GI View Ltd, Ramat Gan, Israel): Workstation and Disposable unit consisting of a rectal introducer, supply cable, scanning balloon, scope and rectal balloon. The supply cable connects the disposable unit to the workstation with its joystick and is able to transmit air, water and suction	5.5 mm diameter, 2.5 m length	Pneumatic	White LED, 360 panoramic vision system with CMOS camera with a field of view of 57 degrees	Visualisation and safety	Semi-autonomous	In vivo: n = 56 Human, CRC screening	CIR is 98.2%. Mean withdrawal time is 14 min. Polyp detection rate of 87.5%. 0 patients had submucosal damage. No complications at 48 h follow up. Rated as excellent visualisation by endoscopists
Gluck et al[37], 2015 (Israel)	Aer-O-scope (GI View Ltd, Ramat Gan, Israel): Workstation and Disposable unit consisting of a rectal introducer, supply cable, scanning balloon, scope and rectal balloon. The supply cable connects the disposable unit to the workstation with its joystick and is able to transmit air, water and suction	5.5 mm diameter, 2.5 m length	Pneumatic	White LED, 360 panoramic vision system with CMOS camera with a field of view of 57 degrees	Visualisation and detection	Semi-autonomous	In vivo: n = 12 pigs with surgically simulated colonic ‘polyps’	A total of 36 Aer-O-scope and 24 colonoscopy procedures were performed. The Aer-o-scope visualised 94.9% of polyps compared to 86.8% with colonoscopy. This was significant (P = 0.002). Miss rates for polyps was 5.1% with Aer-O-scope and 13.2% (P = 0.002) with conventional colonoscopy. This significant difference is true for > 6 mm polyps
Cosentino et al[38], 2009 (Italy)	Endotics System [ERA Endoscopy S.r.l., Peccioli (Pisa), Italy]: Workstation with console and disposable flexible probe. The probe has 2 clampers to aid locomotion and a head (contains the camera, LEDs and channels for suction, irrigation and insufflation) a body and a tail	23-37 cm in length, 17 mm in diameter	Pneumatic	LED light source and CMOS camera with a field of view of 110 degrees	Visualisation and Safety	Semi-autonomous	Ex vivo: n = 1 porcine colon fixed to a human adult abdominal phantom. In vivo: n = 40 Humans, with a family Hx of CRC, known previous polyps and FOB positive requiring investigation	Ex vivo: The stress pattern was 90% less than with colonoscopy. In vivo: CIR was 27% for the endotics system compared to 82% with colonoscopy. The mean CIT was 57 min. The endotics system was described as less painful (0.9 vs 6.9). The endotics system has a higher diagnostic accuracy as it detected 2 polyps and 2 angiodysplastic lesions not identified with colonoscopy
Tumino et al[39], 2010 (Italy)	Endotics System (ERA Endoscopy S.r.l., Peccioli (Pisa), Italy): Workstation with console and disposable flexible probe. The probe has 2 clampers to aid locomotion and a head (contains the camera, LEDs and channels for suction, irrigation and insufflation) a body and a tail	25-43 cm in length, 17 mm in diameter	Pneumatic	LED light source and CMOS camera with a field of view of 110 degrees	Visualisation, sensitivity and specificity	Semi-autonomous	In vivo: n = 71 Humans, with a family Hx of CRC or polyps	Endotics system versus colonoscopy: CIR: 81.6% vs 94.3%. The average time for procedure completion: 45 min vs 23 min (P < 0.001). Patients requiring sedation: 0% vs 19.7% (P < 0.001). Endotics system for detecting polyps: Sensitivity: 93.3%; Specificity: 100%; Positive predictive value: 100%; Negative predictive value: 97.7%
Trecca et al[40], 2020 (Italy)	Endotics System [ERA Endoscopy S.r.l., Peccioli (Pisa), Italy]: Second generation system- Workstation with console and disposable flexible probe. The probe has 2 clampers to aid locomotion and a head (contains the camera, LEDs, chromoendoscopy and channels for suction, irrigation and insufflation) a body and a tail	23-37 cm in length, 17 mm in diameter	Pneumatic	LED light source, chromoendoscopy and CMOS camera with a field of view of 140 degrees	Learning curve, visualisation and diagnostic accuracy, safety	Semi-autonomous	In vivo: n = 55 Humans, requiring diagnosis, CRC screening or surveillance. Training progress was evaluated by comparing two consecutive blocks of patients i.e. group A (first 27) and group B (last 28)	CIR is 92.7%. Median CIT is 29 min. Median withdrawal time is 18 min. Polyp detection rate: 40%; Adenoma detection rate: 26.7%; Advanced neoplasm: 0%; Complication: 1.8%-bleeding with polypectomy; Successful polypectomy and hot biopsy coagulation for bleeding. Mean VAS pain/discomfort: 1.8. Learning curve assessment, Group A vs Group B: CIR: 85.2% vs 100%. Median CIT: 55 min vs 22 min (P = 0.0007). Median withdrawal time: 21 min vs 16 min
Tumino et al[41], 2017 (Italy)	Endotics System (ERA Endoscopy S.r.l., Peccioli (Pisa), Italy): Workstation with console and disposable flexible probe. The probe has 2 clampers to aid locomotion and a head (contains the camera, LEDs and channels for suction, irrigation and insufflation) a body and a tail	25-43 cm in length, 17 mm in diameter	Pneumatic	LED light source and CMOS camera with a field of view of 110 degrees	Visualisation and performance	Semi-autonomous	In vivo: n = 102 Humans, previously failed caecal intubation on colonoscopy	CIR was 93.1% and therefore had a 95% performance. Mean CIT was 51 min
Shike et al[42], 2008 (Italy/Israel/United States)	Sightline ColonoSight (Stryker GI, Dallas, Tex, Haifa, Israel): A reusable scope with LEDs and camera at the tip and steering dials proximally. Tips is covered by a disposable sleeve with 3 working channels for suction, irrigation, insufflation and instruments. Electropneumatic unit, control unit and video monitor	Not described	Pneumatic	LED light source and camera	Visualisation, diagnosis and treatment	Semi-autonomous	In vivo: 2 pigs–To assess safety in terms of bacterial transmission to the reusable scope with a disposable sleeve covering. In vivo: 178 Humans, healthy volunteers and various clinical indications for colonoscopy	In vivo, Pigs: E.coli and E. Fergusonii from scope handle, shaft and tip before the procedure: Nil growth. E.coli and E. Fergusonii from scope handle, shaft and tip after the procedure: Nil growth. E.coli and E. Fergusonii from sheath covering after the procedure: Heavy growth. In vivo, Humans: CIR is 90%. Mean CIT is 11.2 min. Diagnoses of diverticulosis, polyps, colitis, haemorrhoids, normal or other was given. Successful polypectomy, biopsy and argon plasma coagulation. No complications at 2 wk follow up
Ng et al[43], 2000 (Singapore)	EndoCrawler: Longitudinal and circumferential rubber bellow actuators joined in four segments with a bending tube to allow steering between the first two segments and vision module; Central hollow cavity for instruments, insufflation, irrigation and suction channels and CCD cables. These exit the proximal end as a flexible cable similar to a colonoscope; LabWindows user interface and joystick	28 mm in diameter, 420 mm length	Pneumatic	CCD camera and light source	Locomotion and visualisation	Direct robot operation	Ex vivo- Cadaveric colon. In vivo-Pig	Ex vivo: Clear visualisation of colonic wall. Speed: 200 mm/min however required external pushing and couldn’t progress beyond bends unless the head was deflected away from the colonic wall. In vivo: ‘Red out’ images throughout most of the robot’s journey. Average speed: 150 mm/min with external pushing. Unable to progress beyond an acute bend
Dehghani et al[44], 2017 (United States)	Pneumatically driven colonoscopy robot consisting of the robot (tip with camera, latex tubing, tethered camera and anal fixture) and external pneumatic circuit and electric circuit with laptop	Not described	Pneumatic	Camera	Locomotion feasibility and safety	Semi-autonomous	Ex vivo: 1.5 m porcine colon in human phantom. Tests repeated 5-14 times depending on analysis performed	Able to traverse the entire length 71.4% (10/14 trials). Able to traverse the entire length with additional bends 90.9% (10/11 trials). Robot speed of 28 mm/s (5 trials). Average CIT is 54.2 s. (5 trials). Maximum propulsive force is 6 N (44 mmHg) which is less than the safe intraluminal pressure of 80 mmHg. Balloon rupture led to damage including tearing of the porcine colon
Chen et al[45], 2019 (China)	Soft endoscopic device which consists of two gripper segments and one propulsion segment. Each segment contains two soft pneumatic balloons and two rigid connectors. The balloons are twisted in the gripper segments but linear in the propulsion segment. The connectors contain inner channels for air flow and instruments; Lab view interface. Air compressor with regulators, pressure sensors, valves and air pipes connected to the endoscopic device and a power source	The unactuated device is 95 mm in length and 22 mm in diameter.	Pneumatic	CCD camera	Locomotion and visualisation capability	Semi-autonomous	Ex vivo: Pig colon-one end fixed to a pipe, the other free. Colon placed in a horizontal position	Velocity to traverse the colon: 1 mm/s. Clear visualisation of the colonic mucosa
Coleman et al[47], 2016 (United Kingdom)	Hydraulic colonoscope system: A CV connected to extra-corporeal pumps and valves via a tether. The CV contains a magnetic tracker and is surrounded by a balloon which is flexible and may be inflated or deflated. The pump system is used to pump water into the colon behind the CV; Anal port and control system on HMI	CV dimensions not described. Tether: 1.8 m long, 6 mm in diameter	Hydraulic	No camera in this prototype however a dummy with a diameter if 11 mm and length of 25 mm is incorporated to simulate its presence	Comparison of CV locomotion under manual control or automatic control to colonoscopy	Direct or semi-autonomous	Ex vivo: Two 120 cm porcine colon placed in human abdominal phantom–6 trials per manual control, automatic control and colonoscopy	100% CV reached the caecum. CV vs colonoscopy: CIT: 3.95 vs 4.91 min (P = 0.43). Maximum force to the colon: 0.63 vs 2.2 N (P = 0.004). Maximum anal pressure: 1.53 vs 4.53 kPa (P = 1 × 10-7). Mean anal pressure: 0.65 vs 1.5 kPa (P = 0.0003). No difference in maximum or mean caecal pressure. Manual CV versus Auto CV: CIT: 2.11 vs 5.79 min (P = 0.02). Mean anal pressure: 1.86 vs 1.31 kPa (P = 0.03). No difference maximal anal pressure and maximum or mean caecal pressure

LEDs: Light emitting diodes; CMOS: Complementary metal-oxide-semiconductor; CIR: Caecal intubation rate; CIT: Caecal intubation time; CCD: Charged coupled device; HMI: Human machine interface; CV: Colonic vehicle.