Implementation of a novel efficacy score to compare sealing and cutting devices in a porcine model

Simultaneous sealing and bisection of porcine renal blood vessels, ex vivo, using a continuous-wave, infrared diode laser at 1470 nm

Electrosurgical and ultrasonic devices are used in surgical procedures for hemostatic sealing and bisection of vascular tissues. Previous benchtop studies alternatively demonstrated successful infrared laser sealing and cutting of blood vessels, in a sequential, two-step approach. This study describes a smaller, laparoscopic device compatible design, and simultaneous approach to sealing and bisection of vessels, with potential optical feedback. A 1470-nm infrared diode laser sealed and bisected 40 porcine renal arteries, ex vivo. A reciprocating, side-firing, optical fiber, housed in a transparent square quartz optical chamber (2.7 × 2.7 × 25 mm outer dimensions), delivered laser energy over an 11 mm scan length, with a range of incident powers (41-59 W) and treatment times (5-21 s). Vessel diameters ranged from 2.5 to 4.8 mm. Vessel burst pressure measurements were performed on each cut end (n = 80) with success indicated by pressures exceeding 360 mmHg. All vessel ends were successfully sealed and bisected (80/80). The highest incident power, 59 W, yielded short treatment times of 5-6 s. Peak temperatures on the external chamber surface reached 103 oC. Time to cool down to body temperature measured 37 s. Infrared lasers simultaneously seal and bisect blood vessels, with treatment times comparable to, and temperatures and cooling times lower than reported for conventional devices. Future work will focus on integrating the fiber and chamber into a standard 5-mm-outer-diameter laparoscopic device. Customization of fiber scan length to match vessel size may also reduce laser energy deposition, enabling lower peak temperatures, treatment times, and cooling times.

Comparison of quartz and sapphire optical chambers for infrared laser sealing of vascular tissues using a reciprocating, side-firing optical fiber: Simulations and experiments

INTRODUCTION

Infrared (IR) lasers are being tested as an alternative to radiofrequency (RF) and ultrasonic (US) surgical devices for hemostatic sealing of vascular tissues. In previous studies, a side-firing optical fiber with elliptical IR beam output was reciprocated, producing a linear IR laser beam pattern for uniform sealing of blood vessels. Technical challenges include limited field-of-view of vessel position within the metallic device jaws, and matching fiber scan length to variable vessel sizes. A transparent jaw may improve visibility and enable custom treatment.

METHODS

Quartz and sapphire square optical chambers (2.7 × 2.7 × 25 [mm3 ] outer dimensions) were tested, capable of fitting into a 5-mm-OD laparoscopic device. A 1470 nm laser was used for optical transmission studies. Razor blade scans and an IR beam profiler acquired fiber (550-µm-core/0.22NA) output beam profiles. Thermocouples recorded peak temperatures and cooling times on internal and external chamber surfaces. Optical fibers with angle polished distal tips delivered 94% of light at a 90° angle. Porcine renal arteries with diameters of 3.4 ± 0.7 mm (n = 13) for quartz and 3.2 ± 0.7 mm (n = 14) for sapphire chambers (p > 0.05), were sealed using 30 W for 5 s.

RESULTS

Reflection losses at material/air interfaces were 3.3% and 7.4% for quartz and sapphire. Peak temperatures on the external chamber surface averaged 74 ± 8°C and 73 ± 10°C (p > 0.05). Times to cool down to 37°C measured 13 ± 4 s and 27 ± 7 s (p < 0.05). Vessel burst pressures (BP) averaged 883 ± 393 mmHg and 412 ± 330 mmHg (p < 0.05). For quartz, 13/13 (100%) vessels were sealed (BP > 360 mmHg), versus 9/14 (64%) for sapphire. Computer simulations for the quartz chamber yielded peak temperatures (78°C) and cooling times (16 s) similar to experiments.

CONCLUSIONS

Quartz is an inexpensive material for use in a laparoscopic device jaw, providing more consistent vessel seals and faster cooling times than sapphire and current RF and US devices.

A Real-Time Fluorescence Feedback System for Infrared Laser Sealing of Blood Vessels

This study explores UV light induced fluorescence from blood vessels for indicating successful infrared laser sealing of vascular tissues. A light emitting diode (LED) with center wavelength of 340 nm and 0.1 mW power was used with a Y-shaped fiber bundle of seven 200-μm-core fibers. The central excitation fiber was connected to the LED, while the detection ring of six fibers was connected to a spectrometer. The fiber bundle was aligned with porcine renal arteries compressed between optical windows. Fluorescence was acquired before and after vessel sealing, with a 1470 nm laser for 5 s at 30 W (sealing, n = 10) or 5 W (control, n = 10). Signal increase in the 470-520 nm spectrum was correlated with vessel burst pressures (BP). Integrated fluorescence increased 71 ± 25% at 30 W vs. 19 ± 14% at 5 W (p < 0.05), corresponding to a successful BP of 639 ± 189 mmHg vs. failed seal BP of 39 ± 41 mmHg (p < 0.05). Real-time measurements showed a gradual increase in fluorescence with the signal reaching a plateau at 3-4 s, indicating that shorter seal times are possible. The increase in fluorescence signal during laser vessel sealing may provide a non-destructive, real-time, optical method for indicating hemostatic seals.

Ovarian tissue health after laparoscopic unilateral oophorectomy: A porcine model for establishing optimized fertility preservation techniques in children

BACKGROUND

The only pre-treatment fertility preservation option for prepubertal girls, who are at risk for infertility due to their diagnosis or treatment, is surgical removal of ovarian tissue for cryopreservation (OTC). We investigated ovarian tissue health following isolation with an ultrasonic advanced energy device (UAED), that has a previously reported thermal spread of ≤2 cm.

METHODS

The ovaries of eight Yucatan minipigs were isolated by laparoscopy (1) close dissection with the UAED located up to 2 mm away from the ovarian capsule, (2) far dissection with the UAED located >2 cm away, or by (3) laparotomy for control ovaries using cold scissors. Ovarian cortex tissues were cultured for 4 days to assess tissue health.

RESULTS

Ovarian cortex tissue isolated using a UAED produced an altered metabolic ratio in both the far and close dissection compared to control (p < 0.001). There was an increase in folliculogenesis in the control samples over samples isolated with far and close dissection (p < 0.0001), and a reduction in estradiol production in experimental groups (p < 0.0001).

CONCLUSIONS

This model defines differences in ovarian tissue health among different isolation techniques. Ongoing work will further define the standard of care surgical technique for OTC.

Evaluation of the performance of an endoscopic 3-mm electrothermal bipolar vessel sealing device intended for single use after multiple use-and-resterilization cycles

OBJECTIVE

To evaluate the performance of an endoscopic 3-mm electrothermal bipolar vessel sealing device (EBVS) intended for single use after multiple use-and-resterilization cycles.

STUDY DESIGN

Ex vivo study.

SAMPLE POPULATION

Eight 3-mm EBVS handpieces.

METHODS

Handpieces were subjected to a maximum of 15 cycles of testing, including simulated surgery, sealing and burst pressure testing of porcine carotid arteries, reprocessing, and hydrogen peroxide plasma resterilization. Failure was defined as two sequential vascular seal leakage events occurring at <250 mm Hg. Histological evaluation, maximum external temperature of the jaws, sealing time, tissue adherence, jaw surface characterization, and mechanical deterioration were studied. Failure rate was analyzed by using a Kaplan-Meier curve. Linear and ordinal logistic mixed models were used to analyze sealing time, handpiece jaw temperature, and adherence score.

RESULTS

Mean ± SD diameter of arteries was 3.22 ± 0.35 mm. Failure was observed starting at cycle 10 and going up to cycle 13 in 37.5% (3/8) of the handpieces. Tissue adherence increased after each cycle (P < .001). Maximum external temperature (79.8°C ± 13.9°C) and sealing time (1.8 ± 0.5 seconds) were not significantly different throughout cycles up to failure. A flatter surface and large scratches were observed microscopically throughout the jaw surface after repeated use and resterilization.

CONCLUSION

The 3-mm EBVS handpiece evaluated in this study can be considered safe to use for up to nine reuse-and-resterilization cycles.

CLINICAL SIGNIFICANCE

These data provide the basis for establishing preliminary guidelines for the reuse and hydrogen peroxide plasma resterilization of an endoscopic 3-mm EBVS handpiece.