Ex vivo experimental study on the Thulium laser system: new horizons for interventional endoscopy (with videos)

Use of lasers in gastrointestinal endoscopy: a review of the literature

Lasers emit highly directional light with consistent wavelengths, and recent studies have demonstrated their successful applications in gastrointestinal endoscopic therapy. Although argon plasma coagulators (APC) became the preferred treatment option due to improved safety profile and lower costs, advancements in laser and optic fiber manufacturing have reignited interest in laser treatment. Different laser wavelengths have distinct features and applications based on their tissue absorption coefficient. Lasers with shorter wavelengths are effectively absorbed by hemoglobin, resulting in a good coagulation effect. Near-infrared lasers have ability to ablate solid tumors, while far-infrared lasers can make precise mucosal incisions without causing peripheral thermal damage. Lasers have proven to be highly applicable to endoscopy devices such as endoscopes, endoscopic ultrasound (EUS), double-balloon enteroscopes (DBE), and endoscopic retrograde cholangiopancreatography (ERCP), making them a potent tool to enhance the effectiveness of endoscopic treatments with minimal adverse events. This review aims to help readers understand the applications and effectiveness of lasers in gastrointestinal endoscopy, with the potential to promote the development and application of laser technology in the medical field.

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Objectives and study aims  Recent pilot studies have assessed the feasibility of a novel 1.9-/1.5-μm dual emission endoscopic laser treatment ( _1.9-/1.5-μm DEELT) for endoscopic hemostasis, ablation and resection. In this study, we investigated the safety and efficacy of _1.9-/1.5-μm DEELT in patients with chronic anemia due to gastrointestinal vascular lesions in a real-life multicenter cohort setting.

Patients and methods  Consecutive patients with moderate/severe iron-deficiency anemia undergoing _1.9-/1.5-μm DEELT for upper and lower gastrointestinal bleeding due to vascular lesions were enrolled in three academic referral centers. Safety and successful ablation of vascular lesions were the primary outcomes. Long-term hemoglobin level, blood transfusion requirements, endoscopic severity scores of complex vascular disorders and technical lasing parameters were also assessed. Long-term hemoglobin variations have been further assessed, with repeated measure analysis of variance and univariate analyses.

Results  Fifty patients (median age 74; range 47 to 91 years) with gastric antral vascular ectasia (GAVE) (22), angioectasia (22) and radiation proctopathy (6) underwent 58 _1.9-/1.5-μm DEELT between 2016 and 2020. All procedures were technically feasible leading to successful ablation of the targeted lesion/s, with no incident or adverse event potentially related to the _1.9-/1.5-μm DEELT technique. Within a 6-month follow-up, hemoglobin values significantly rose (+ 1.77 at 1 month and + 1.70 g/dL at 6 months, P  < 0.01), the blood supply requirement decreased (at least one transfusion in 32 versus 13 patients, P  < 0.01), and GAVE lesions showed a clear endoscopic improvement (from 5 points to 1 points, P  < 0.01).

Conclusions  The 1.9-/1.5-μm laser system is a safe and effective endoscopic tool for haemostatic ablation of bleeding vascular lesions within the gastrointestinal tract in tertiary referral centers.

Submucosal thulium laser turbinoplasty in children: assessment of efficacy and comparison with partial inferior turbinectomy

This study aimed to assess efficacy of submucosal thulium laser turbinoplasty in children and to compare thulium laser turbinoplasty with partial inferior turbinectomy. This is a retrospective study over 10 years from 1 January 2009, conducted in a Pediatric Otorhinolaryngology Department in a university tertiary care center, including all the children who underwent thulium laser inferior turbinoplasty and partial inferior turbinectomy. The main outcome measures were the improvement in airflow using rhinomanometric cumulative flow at 150 Pa and then functional improvement using "OPERAS" score (nasal Obstruction, facial Pain, Epistaxis, Rhinorrhea, Anosmia, Sneezing). Eighty-six children underwent 47 submucosal thulium laser turbinoplasties and 48 partial turbinectomies. After submucosal thulium laser turbinoplasty, the cumulative flow at 150 Pa improved from 308.2 to 454.4 cm³ s^-1 (p < 0.01) and the OPERAS score decrease was 1.5 point (p < 0.01). Daily use of intra nasal corticosteroid and antihistamine both decreased significantly. No local complications of this technique have been reported. Partial turbinectomies show a higher reduction of the OPERAS score and a better improvement of rhinomanometric parameters, but also a significantly higher complication rate. Submucosal thulium laser turbinoplasty is a good compromise between safety and efficacy, with substantial functional and rhinomanometric postoperative improvement.

Microrobotic laser steering for minimally invasive surgery

The creation of multiarticulated mechanisms for use with minimally invasive surgical tools is difficult because of fabrication, assembly, and actuation challenges on the millimeter scale of these devices. Nevertheless, such mechanisms are desirable for granting surgeons greater precision and dexterity to manipulate and visualize tissue at the surgical site. Here, we describe the construction of a complex optoelectromechanical device that can be integrated with existing surgical tools to control the position of a fiber-delivered laser. By using modular assembly and a laminate fabrication method, we are able to create a smaller and higher-bandwidth device than the current state of the art while achieving a range of motion similar to existing tools. The device we present is 6 millimeters in diameter and 16 millimeters in length and is capable of focusing and steering a fiber-delivered laser beam at high speed (1.2-kilohertz bandwidth) over a large range (over ±10 degrees in both of two axes) with excellent static repeatability (200 micrometers).

Evaluations on laser ablation of ex vivo porcine stomach tissue for development of Ho:YAG-assisted endoscopic submucosal dissection (ESD)

Endoscopic submucosal dissection (ESD) is clinically used to remove early gastric cancer in stomach. The aim of the current study is to examine a therapeutic capacity of pulsed Ho:YAG laser for the development of laser-assisted ESD under various surgical parameters. Ex vivo porcine stomach tissue was ablated with 1-J Ho:YAG pulses at 10 Hz at different number of treatments (NT = 1, 2, and 3) and treatment speeds (TS = 0.5, 1, and 2 mm/s) without and with saline injection. Regardless of saline injection, straight tissue ablation showed that ablation depth increased with increasing NT and decreasing TS. At NT = 3 and TS = 0.5 mm/s, no saline injection yielded the maximum ablation depth (3.4 ± 0.3 mm), partially removing muscularis propria. However, saline injection confined the tissue ablation within a submucosal layer (2.1 ± 0.3 mm). Thermal injury was found to be 0.7~1.1 mm in the adjacent tissue with superficial carbonization. Circular tissue ablation (2 cm in diameter) at NT = 3 and TS = 0.5 mm/s presented that no saline injection yielded a reduction in the lesion area, whereas saline injection maintained the ablated lesion area. Histological analysis revealed that unlike no saline injection, saline injection ablated the entire mucosal layer without perforation in the muscular propria. The pulsed Ho:YAG laser can be a potential surgical tool for clinical ESD to incise a target lesion without adverse perforation. Further investigations will validate the efficacy and safety of the Ho:YAG laser-assisted ESD in in vivo porcine stomach models for clinical translation.

Comparison of synchronous dual wavelength diode laser versus conventional endo-knives for esophageal endoscopic submucosal dissection: an animal study

BACKGROUND

Endoscopic submucosal dissection (ESD) is widely used for en bloc resection in early gastrointestinal cancer. However, it is technically complex with long procedure time and high adverse event rates with using conventional knives. The aim of this animal study was to verify the feasibility of ESD using a novel 980/1470 nm dual diode laser (DDL-ESD) in comparison with conventional knives (C-ESD) in esophagus.

METHODS

This was an in vivo animal study using eight porcine models. Four were allocated in DDL-ESD group and four were in C-ESD group. Every model underwent two ESDs to remove half circumferential esophageal mucosa. Each model's esophagus was harvested during postmortem at 24 h after ESD. Each specimen underwent gross inspection and histopathological examination was carried out. Procedure time, completeness of en bloc resection, adverse events (bleeding and perforation) and histological injury to muscularis propria were assessed.

RESULTS

A total of 16 ESD procedures were performed with 100% en bloc resection rate. The procedure speed in DDL-ESD group was significantly faster as compared to C-ESD group (0.27 cm²/min vs. 0.21 cm²/min, p = 0.001). The number of intraoperative bleeding points and the use of haemostatic forceps were significantly lesser in DDL-ESD group (4 ± 2 vs. 8 ± 3, p = 0.016; 1 ± 1 vs. 3 ± 2, p = 0.029). Histological assessment showed that injury to muscularis propria in DDL-ESD was milder than C-ESD. There was no perforation observed in both groups.

CONCLUSIONS

DDL-ESD technique appears to be safer and faster than C-ESD with less bleeding and injury to deep tissues.