Infrared Laser Fusion and Bisection of Blood Vessels with Real-Time Optical Diagnostic Feedback
The conventional method of suture ligation of vascular tissues during surgery is time consuming, skill intensive, and leaves foreign objects in the body. Energy-based radiofrequency(RF) and ultrasonic (US) devices have recently replaced the use of sutures and mechanical clips, providing rapid hemostasis during surgery. These devices expedite numerous labor-intensive surgical procedures, including lobectomy, nephrectomy, gastric bypass, splenectomy, thyroidectomy, hysterectomy, cystectomy, and colectomy. Though these newer methods provide rapid and efficient blood vessel ligation, both US and RF devices have limitations including the potential for unacceptably large collateral thermal damage zones, with thermal spread averaging greater than 1 mm. This lack of precision prevents the use of these devices for delicate surgical procedures performed in confined spaces (such as prostatectomy). These devices may also cause thermal damage to healthy tissue through unintended heat conduction in contact with the device jaws. The active jaw of US devices can reach temperatures in excess of 200 C during a single application and can take greater than 20 s to cool to usable temperatures before proceeding with further applications. The maximum temperatures on the active jaw of RF devices are lower (< 100 C), however, larger thermal spread is observed. This study explores the development of a novel alternative method using near-infrared (IR) lasers for vessel ligation, bisection, and real-time feedback during procedures. This dissertation focuses on the sealing (the act of permanently fusing the lumen of the vessel) and cutting (the act of bisecting a vessel) of the arteries (1-6 mm in diameter), which are the most common vessels sealed with an energy-based device during laparoscopic surgery. There are several potential advantages of laser-based sealing and cutting of vascular tissues compared to conventional US and RF energy-based devices. These include: (1) More rapid sealing and cutting of vascular tissues with seal and cut times as short as 1 s each; (2) More directed deposition of energy into tissue with collateral thermal spread of less than 1 mm; (3) Stronger vessel seals with higher burst pressures (up to 1500 mmHg); (4) An integrated device capable of both optical sealing and cutting of vascular tissues without the need for a separate deployable mechanical blade to bisect tissue seals; (5) Safer thermal profile with lower jaw peak temperatures (< 60 C) compared to ultrasound (~ 200 C) and radiofrequency (~ 100 C) devices; (6) Sealing of large blood vessels greater than 5 mm; and (7) An entirely optical based system with real-time quantitative feedback indicating the success of the thermal seal and/or bisection of the blood vessel. This dissertation will explore these advantages for laser-based technology along with an optical method for real – time optical feedback all with the capability of laparoscopic device integration.