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

Abstract

AbstractIntroductionInfrared (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.MethodsQuartz 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.ResultsReflection 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.ConclusionsQuartz 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.