Ex vivo and animal study of the blue diode laser, Tm fiber laser, and their combination for laparoscopic partial nephrectomy

An ex vivo experimental study comparing the effects of the holmium: yttrium-aluminum-garnet and thulium fiber lasers on testicular tissue

The effects of lasers on testicular tissue have not yet been investigated in detail. In this experimental ex vivo study, we aimed to demonstrate and compare the effects of the holmium:yttrium-aluminum-garnet (Ho:YAG) and thulium fiber laser (TFL) lasers on testicular tissue. An ex vivo experiment was performed using calf testes. A 100W Ho:YAG laser and a 60W TFL devices with a setting spectrum at 10-60W, a frequency of 20-40 Hz, energy levels at 0.5-1-1.5 J, and medium pulse duration were tested. Histopathological parameters such as Incision depth (ID), vaporization area (VA), coagulation area (CA), and total laser area (TLA = VA + CA) were evaluated. In testicular tissue without a tunica layer, a statistically significant difference was found in the mean VA and TLA values between the Ho:YAG and TFL, in favor of Ho:YAG (p = 0.003, p = 0.003, respectively). In testicular tissue with a tunica layer, there was a statistically significant difference in mean VA, CA, TLA, ID values between Ho:YAG and TFL, in favor of Ho:YAG (all p < 0.001). At 1.5 J-20 Hz and 1.5 J-40 Hz, we observed that the features indicating tissue dissection, such as VA and ID, were lower in the TFL than those in Ho:YAG, while CA values were higher. VA, CA, TLA, ID values were significantly increased in tissue with tunica compared to non-tunicated tissue in both the Ho:YAG and TFL applications. At 30W and 60W, the penetrative effect of the TFL on tissue was less than that of the Ho:YAG, but its coagulation property was superior. What is Known: • Ho:YAG and TFL lasers are widely used in urology, primarily for stone and prostate surgeries, with established tissue effects in these contexts. What is New: • This study is the first to examine and compare the histopathological effects of these lasers on testicular tissue, providing insights into their potential applications in testicular surgery.

Exploring the optimal parameter settings of a thulium fiber laser during soft tissue resection

There is a lack of clinical consensus on the parameter settings of the pulsed-wave thulium fiber laser for soft tissue resection. The aim of this study was to explore the optimal parameter settings of the pulsed-wave thulium fiber laser for soft tissue resection, with a view to providing a reference for future clinical applications. Two different thulium fiber lasers, prototype thulium fiber lasers and Urolase, were used to explore the optimal parameters of thulium fiber laser for soft tissue cutting by evaluating the depth of tissue vaporization and depth of thermal damage in an isolated pig kidney model, and then the optimal parameters of in vitro screening were statistically validated by operation time, coagulation time, intraoperative hemorrhage, smoke level, and depth of thermal damage in an in vivo model using rabbit kidney. In ex vivo animal experiments the depth of tissue vaporization and thermal damage increased with increasing average power, and tissue carbonization occurred at 30 W. In animal use we used 1 J, 25 W for surgery, and there was no statistical difference between the two thulium fiber lasers in terms of surgery time, coagulation time, bleeding, smoke level, and depth of thermal damage. Thulium fiber laser for soft tissue resection is safe and feasible, and we believe that 1 J, 25 W is the optimal laser setting parameter for soft tissue resection, but it needs to be adjusted according to the actual situation.

Comparison of the effects of Ho: YAG laser virtual Basket™ pulse modulation and Thulium fiber laser on kidney tissue - an ex vivo experimental study

Through an ex vivo experimental study, we aimed to compare the effects of the Ho: YAG laser Virtual Basket (VB™) modulation and a Thulium fiber laser (TFL) on kidney tissue in different environments and using laser configurations. The 100 W Ho: YAG (Cyber Ho, Quanta System, Italy) and 60 W TFL (Fiber Dust, Quanta System, Italy) laser devices were used. The following laser settings were selected: power in the range of 10-60 W, frequency of 20-40 Hz, and energy of 0.5-1-1.5 J. A medium pulse duration of 600 µsec was used for VB™, while short (spdTFL; 50 µsec) and long (lpdTFL; 15,000 µsec) were used for TFL. The tissue's incision depth (ID), vaporization area (VA), coagulation area (CA), total laser area (TLA = VA + CA), surface section (SS), and lateral effect (LE) were measured. In total, 108 experiments were conducted. No statistically significant difference in mean VA, TLA, ID, LE, or SS was observed between VB™, spdTFL, and lpdTFL in the low-power output group in saline (p > 0.05). However, the mean CA was statistically significantly higher for VB™ (p = 0.005). In saline and high-power output group, the mean VA, CA, TLA, LE, and ID were higher when using lpdTFL than other pulse durations (p = 0.001, p = 0.001, p = 0.001, p = 0.006, and p = 0.001, respectively). Similar to lpdTFL, VB™ may provide controlled dissection and incision as well as haemostasis. At different laser settings, the individual effects of laser properties (such as pulse length, energy and frequency) on tissue may be more significant.

Laser-Induced Blood Coagulation for Surgical Application: A Scoping Review

There is a lack of evidence-based reviews on the effects of laser irradiation on blood coagulation in the literature, despite a large number of clinical trials. We therefore evaluated the available evidence on laser irradiation parameters used in coagulation of blood to optimize physical parameters. We performed a literature search for recent scientific studies indexed between 2017 and 2023 using the databases of PubMed and ScienceDirect. Articles were selected based on defined inclusion and exclusion criteria, and 78 publications in total were eventually included in this scoping review. The following were found to produce significant benefits in blood coagulation for surgical application: (1) dentistry and oral surgeries: 980 nm, 27 s, 2 W, 1502.7 W/cm2, 26.5 J, 622 J/cm2, 400 μm; (2) urogenital disorders: 532 nm, 4 s, 40 W, 10600 W/cm2, 1.3 J, 424 J/cm2, 600 μm; (3) ophthalmic disorders: 810 nm, 1 s, 1 W, 3540 W/cm2, 0.75 J, 1326 J/cm2, 100 μm; (4) embryological surgeries: 1064 nm, 10 s, 25 W, 35400 W/cm2, 262.5 J, 371000 J/cm2, 332.5 μm; (5) dermatological disorders: 1064 nm, 20 W, 2440 W/cm2, 0.1 J, 24 J/cm2, 670 μm; (6) gastrointestinal disorders: 532 nm, 3 s, 20 W, 1051 W/cm2, 120 J, 26500 J/cm2, 760 μm; (7) neurological surgeries: 2.5 s, 1.5 W, 1035 W/cm2, 2 J, 1584 J/cm2, 385 μm; (8) pulmonary disorders: 1320 nm, 5s, 35 W, 12450 W/cm2, 250 J, 65000 J/cm2, 700 μm (9) cardiovascular disorders: 1064 nm, 16.5 s, 5 W, 1980.5 W/cm2, 900 J, 760 J/cm2, 400 μm. In conclusion, our scoping review identifies that combining data from all clinically heterogeneous studies suggests that laser irradiation reflects an effective method for inducing blood coagulation in several medical fields.

450-nm blue diode laser: a novel medical apparatus for upper tract urothelial lesions

OBJECTIVE

To explore the feasibility, safety and effectiveness of the 450-nm blue diode laser (BL), novel blue laser in the treatment of upper tract urothelial carcinomas (UTUCs) and other lesions in a porcine model.

MATERIAL AND METHODS

For in vitro experiment, the ureter tissue was vaporised and coagulated with BL, green-light laser (GL) and Ho:YAG laser (Ho). The efficiency, width and depth of vaporisation, and depth of coagulation were recorded and compared. For in vivo experiments, four swines weighing 70 kg were used. In the acute group, different modes of operations were performed to evaluate the thermal damage, perforation and bleeding. In the chronic group, the overall appearance of the ureter and laser wound healing were observed by the naked eyes and H&E staining 3 weeks after surgery.

RESULTS

In in vitro study, the BL showed a higher efficiency of tissue vaporisation and less tissue coagulation for fresh ureter compared to GL and Ho. In the in vivo study, the power of BL set at 7 W was better, and the thickness of thermal damage varied with different surgery types in the range of 74-306 μm. After 3 weeks, the wound healed well static in vaporisation (SV), moving vaporisation (MV) and H&E staining indicated mucosal healing rather than scar healing.

CONCLUSION

5-10W blue diode laser achieved a higher efficiency of tissue vaporisation and less tissue coagulation in a porcine model, indicating its potential application in the endoscopic surgery of UTUC as an optional device with high performance and safety.

Could Testicular Tissue Be a New Arena for the Holmium Laser?

Introduction We aimed to observe the effects of holmium:yttrium-aluminum-garnet (Ho:YAG) laser on testicular tissue. Methods An ex vivo experiment was conducted using calf testicles. A 100 W laser generator with broad-spectrum settings of 10-80 W, 20-40 Hz, and 0.5-2 J, with a medium pulse duration, was tested. The laser effects on testicular tissues with and without the tunica layer were evaluated histopathologically by calculating the incision depth (ID), vaporization area (VA), coagulation area (CA), and total laser area (TLA=VA+CA) of the specimens. Results A total of 48 experiments were conducted. In testicular tissue without a tunica layer, the highest mean ID was determined at 1 J-20 Hz (0.247±0.0208 mm) and with a tunica layer at 2 J-40 Hz (2.673±0.032 mm). In the testicular tissue without a tunica layer, the highest mean VA was determined at 1.5 J-40 Hz (0.029±0.0016 mm2) and in tissue with a tunica at 2 J-40 Hz (6.173±0.114 mm2). The highest mean TLA in tissue without a tunica was detected at 2 J-20 Hz (0.038±0.0008 mm2) and in tissue with a tunica at 2 J-40 Hz (7.292±0.07 mm2). The mean ID, VA, CA, and TLA values of all the power outputs used were found to be statistically significantly higher in the testicular tissue with the tunica layer than in that without it (p<0.001). Conclusion The Ho:YAG laser has different effects on testicular tissue with and without a tunica layer. In testicular tissue without a tunica, the laser's effect was minimal on the surrounding tissue, especially in terms of the ID, VA, and TLA. This minimal effect of the laser can be an advantage in testicular surgery procedures such as testis-sparing surgery (TSS) or testicular sperm extraction (TESE).

Preclinical optimization of a diode laser-based clamp-free partial nephrectomy in a large animal model

Kidney cancer is a common urologic malignancy with either laparoscopic (LPN) or robotic partial nephrectomy as therapeutic options of choice for localized tumors. However, renal resection and suturing are challenging steps of the procedure that can lead to complications such as prolonged warm ischemia, bleeding, and urinary fistulas. LPN with a diode laser is an efficient technique due to its cutting and/or coagulation attributes. Surprisingly, key laser features such as wavelength and power remain undefined. Using a large porcine model, we evaluated the laser range of wavelength and power in a clamp-free LPN and compared it to the established gold-standard LPN technique (i.e., cold-cutting and suturing). By analyzing surgery duration, bleeding, presence of urine leak, tissue damage related to the resected renal fragment and the remaining organ, hemoglobin levels, and renal function, we show that an optimized experimental diode laser clamp-free LPN (wavelength, 980 nm; power, 15 W) had shorter surgery time with less bleeding, and better postoperative renal function recovery when compared to the well-established technique. Together, our data indicate that partial nephrectomy with a diode laser clamp-free LPN technique is an improved alternative to the gold-standard technique. Therefore, translational clinical trials towards human patient applications are readily feasible.

Radiofrequency impedance monitoring of the biological tissues under local heating by optical radiation

Development of methods for simultaneous control of state of biological tissues during optical treatment is the important tasks in laser surgery. We introduce a novel approach for the monitoring of the state of biological tissues in the process of its local heating by optical radiation. It is based on measurements of the electrical radiofrequency impedance kinetics of the sample during irradiation. The obtained data are processed using interconnected mathematical modeling of corresponding thermodynamic, optical and electrical problems. Experimental applications of this approach, represented in the paper, reveal its high sensitivity, repeatability and consistency with the model. The introduced method can be used for the selection and optimization of radiation parameters of medical laser sources as an alternative or an addition to histological techniques. Radiofrequency impedance measurement can be used directly in the course of surgical operations for monitoring the treated tissues state, including its temperature and degree of damage.

Lasers in laparoscopic and robotic surgery: is there a need for them

PURPOSE OF REVIEW

The application of lasers in treating urological disorders is a developing area. In the laparoscopic and robotic surgery, laser energy is not so popular as in the treatment of stone disease and benign prostatic hyperplasia. The aim of this review is to clarify the current status of laser applications in laparoscopic and robotic urology.

RECENT FINDINGS

Laser welding of the pyeloureteral anastomosis is not performed in routine clinical practice. Most investigation of laser applications in laparoscopic and robotic urology has centered on laparoscopic partial nephrectomy and robot-assisted partial nephrectomy. Much less work has been done with regard to lower tract laser laparoscopic and robotic applications. However, laser laparoscopic radical prostatectomy has been investigated.

SUMMARY

Current literature regarding lasers in laparoscopic and robotic surgery is extremely limited. Available data consist mostly of small cohorts providing a low level of evidence. Even though initial studies with currently available laser modalities demonstrated promising results, several drawbacks in each technique need to be addressed before being widely accepted as a standard care. Despite investigation, laser usage during laparoscopic and robotic urological procedures has not gained widespread acceptance and remains experimental at this time.

Retroperitoneoscopic partial nephrectomy using a 980/1470-nm dual-diode laser for small exophytic renal tumors

Laser-supported laparoscopic partial nephrectomy is a promising new technique, but remains under experiment. We presented our single institutional experience of laparoscopic partial nephrectomy using the 980/1470-nm dual-diode laser system to investigate its feasibility, and oncological and functional outcomes. The study retrospectively evaluated 25 patients with small exophytic renal tumors, who underwent laparoscopic partial nephrectomy using a 980/1470-nm dual-diode laser. The demographics, surgical data, complications, pathological variables, oncological, and functional outcomes were reviewed. The changes in hemoglobin and estimated glomerular filtration rate (eGFR) before and after surgery were statistically analyzed. The investigators operated on a total of 25 patients. The off-clamping technique was performed for 23 cases, while the other two cases required renal artery clamping due to unsatisfactory hemostasis. The tumor diameter was 24.6± 6.2 mm, and the mean operative time was 104.4± 23.4 min. The median estimated intraoperative blood loss (EBL) was 100 ml (range 50-600 ml). No major complications (Clavien-Dindo >II) occurred perioperatively. The mean change in hemoglobin before and after the operation was 9 g/l, with a P value of <0.001. The mean decrease in eGFR from before the surgery to the 6-month follow-up was 1.4 ml/min, with a P value of 0.463. The postoperative histopathology evaluation did not demonstrate a positive surgical margin. No recurrence or metastasis was found during the follow-up (mean 24 months). Laparoscopic partial nephrectomy using a 980/1470 nm dual-diode laser appears to be a feasible and oncological satisfactory technique for the treatment of small renal mass (SRM), with the advantages of reducing warm ischemia time.

The impact of the laser fiber-tissue distance on histological parameters in a porcine kidney model

PURPOSE

To evaluate the impact of the fiber-tissue distance on histological parameters in a porcine kidney model.

METHODS

Four lasers were tested at 60 W using a 600-µm bare-ended fiber: a continuous wave (cw) thulium fiber laser (TFL), a super pulsed (SP) TFL, a Ho:YAG laser, and a blue diode laser (BDL). All tissue samples were mounted on a motorized XY-translation stage. The fiber-tissue distance was changed within a range from 0to 6 mm. Ten incisions were made with each laser at each distance. Afterwards, the tissue samples were sliced with a microtome for lactate dehydrogenase staining to determine zones of thermal damage.

RESULTS

In contact mode, the largest incision depth was found for the cw TFL (1.7 ± 0.1 mm) compared to the SP TFL (1.0 ± 0.1 mm), BDL (0.9 ± 0.1 mm) and HoYAG laser (1.1 ± 0.1 mm), respectively. With regard to the coagulative properties, the SP TFL and the Ho:YAG laser showed comparable coagulation depths with 0.7 ± 0.1 and 0.6 ± 0.1 mm, respectively. At 2 mm fiber-tissue distance, the Ho:YAG laser was the only laser that vaporized tissue (incision depth: 0.2 ± 0.1 mm). The BDL was the only laser that caused coagulation at a distance of 3-5 mm.

CONCLUSION

Our results support the clinical observation that cw TFL must be defocused for best coagulation, while the coagulation depth of the SP TFL remains nearly constant within the range of 0-3 mm. Increasing the distance of the laser fiber to the tissue up to 5 mm did not cause significant differences with regard to coagulation depth using the BDL.

Use of hemostatic agents for surgical bleeding in laparoscopic partial nephrectomy: Biomaterials perspective

In recent years, there was an abrupt increase in the incidence of renal tumors, which prompt up the appearance of cutting-edge technology, including minimally invasive and organ-preserving approaches, such as laparoscopic partial nephrectomy (LPN). LPN is an innovative technique used to treat small renal masses that have been gaining popularity in the last few decades due to its promissory results. However, the bleeding control remains the main challenge since the majority of currently available hemostatic agents (HAs) used in other surgical specialities are inefficient in LPN. This hurried the search for effective HAs adapted for LPN surgical peculiarities, which resulted on the emergence of different types of topical HAs. The most promising are the natural origin HAs because of their inherent biodegradability, biocompatibility, and lowest toxicity. These properties turn them top interests' candidates as HAs in LPN. In this review, we present a deep overview on the progress achieved in the design of HAs based on natural origin polymers, highlighting their distinguishable characteristics and providing a clear understanding of their hemostat's role in LPN. This way it may be possible to establish a structure-composition properties relation, so that novel HAs for LPN can be designed to explore current unmet medical needs.