Dual‐wavelength‐assisted thermal hemostasis for treatment of benign prostate hyperplasia

Abstract

Laser treatment on a large size of prostate gland often encounters significant bleeding that can prolong the entire procedure and cause urinary complications. The current study investigates the feasibility of dual-wavelength (532 and 980 nm) application to achieve rapid hemostasis for 532-nm laser prostatectomy. Porcine kidney and bleeding phantom models were tested to quantify the degree of the irreversible tissue coagulation and to estimate the time for the complete hemostasis, respectively. The ex vivo kidney testing verifies that the dual-wavelength created up to 40% deeper and 25% wider coagulation regions than a single wavelength does. The bleeding phantom testing demonstrates that due to the enhanced thermal effects, the simultaneous irradiation yields the complete photocoagulation (~11 seconds) whereas 532 or 980 nm hardly stops bleeders. Numerical simulations validate that the combined optical-thermal characteristics of both the wavelengths account for the augmented thermal coagulation. The dual-wavelength-assisted coagulation can be a feasible treatment to entail the rapid hemostasis and to facilitate the laser prostatectomy in an effective manner.

Enhanced photothermal hemostasis using dual wavelengths in an in vivo leporine kidney model

“…Each bleeder was created before laser irradiation. The current study selected 20 W for 532 nm and 40 W for 980 nm for the testing, based upon the previous dosimetry study in order to minimize the animal usage [12]. Three different irradiation modes were evaluated to achieve photothermal hemostasis: 20 W at 532 nm only, 40 W at 980 nm only, and simultaneous irradiation of 532 and 980 nm (i.e., dual-wavelength mode = 20-W 532 nm + 40-W 980 nm).…”

“…Numerical simulations on distribution of temperature and thermal injury were performed to theoretically validate the thermal effects of three irradiation modes on kidney tissue by using a bioheat transfer equation as follows [12,18,19]:…”

“…Thus, the remaining light cannot increase the temperature in a bleeder or reach a deeply located bleeder, leading to incomplete hemostasis. To overcome the inherent limitations of 532 nm, our previous study combined 532 nm with a clinically available infrared wavelength of 980 nm in a perfused tissue model [12]. The infrared wavelength has a long optical penetration depth (up to 5 mm) but suffers from slow heating due to lower light absorption (e.g., 0.43 cm −1 at 980 nm) [13].…”

“…Specifically, 532 nm can coagulate the outflowing blood and increase tissue surface temperature rapidly whereas 980 nm can coagulate deep tissue simultaneously. Hwang et al, reported that the combined wavelengths created a wide coagulation region and presented a rapid and complete hemostasis, compared to a single wavelength [12]. However, the preliminary bench study was performed in an ex vivo tissue model and merely proved the concept of the combined wavelengths for photothermal hemostasis.…”

Optimization of laser osteotomy at 1064 nm using a graphite topical absorber and a nitrogen assist gas jet

“…Thermal ablation using radio frequency AC current is routinely used to treat bone lesions [21]. As well, laser ablation in the thermal regime has shown promise in applications of hemostasis [22], vascular stenosis [23] and cauterization [24], which could prove useful during osteotomy for reducing and/or stopping bone bleeds.…”