Duane E. Kerr

Infrared laser thermal fusion of blood vessels: preliminary ex vivo tissue studies.

Abstract. Suture ligation of blood vessels during surgery can be time-consuming and skill-intensive. Energy-based, electrosurgical, and ultrasonic devices have recently replaced the use of sutures and mechanical clips (which leave foreign objects in the body) for many surgical procedures, providing rapid hemostasis during surgery. However, these devices have the potential to create an undesirably large collateral zone of thermal damage and tissue necrosis. We explore an alternative energy-based technology, infrared lasers, for rapid and precise thermal coagulation and fusion of the blood vessel walls. Seven near-infrared lasers (808, 980, 1075, 1470, 1550, 1850 to 1880, and 1908 nm) were tested during preliminary tissue studies. Studies were performed using fresh porcine renal vessels, ex vivo, with native diameters of 1 to 6 mm, and vessel walls flattened to a total thickness of 0.4 mm. A linear beam profile was applied normal to the vessel for narrow, full-width thermal coagulation. The laser irradiation time was 5 s. Vessel burst pressure measurements were used to determine seal strength. The 1470 nm laser wavelength demonstrated the capability of sealing a wide range of blood vessels from 1 to 6 mm diameter with burst strengths of 578±154, 530±171, and 426±174  mmHg for small, medium, and large vessel diameters, respectively. Lateral thermal coagulation zones (including the seal) measured 1.0±0.4  mm on vessels sealed at this wavelength. Other laser wavelengths (1550, 1850 to 1880, and 1908 nm) were also capable of sealing vessels, but were limited by lower vessel seal pressures, excessive charring, and/or limited power output preventing treatment of large vessels (>4  mm outer diameter).

Infrared laser sealing of porcine vascular tissues using a 1,470 nm diode laser: Preliminary in vivo studies

Infrared (IR) lasers are being explored as an alternative to radiofrequency (RF) and ultrasonic (US) devices for rapid hemostasis with minimal collateral zones of thermal damage and tissue necrosis. Previously, a 1,470 nm IR laser sealed and cut ex vivo porcine renal arteries of 1–8 mm diameter in 2 seconds, yielding burst pressures greater than 1,200 mmHg and thermal coagulation zones less than 3 mm. This preliminary study describes in vivo testing of a handheld laser probe in a porcine model.

Thermal sealing of blood vessels using infrared lasers

Suture ligation of blood vessels during surgery can be time-consuming and skill-intensive. Energy-based, electrosurgical and ultrasonic devices have recently replaced sutures for many surgical procedures, providing rapid hemostasis during surgery. However, these devices have the potential to create large collateral zones of thermal damage and tissue necrosis. This study explores infrared (IR) lasers as an alternative technology for rapid and precise thermal coagulation and sealing of blood vessels. Eight near-IR lasers (808, 980, 1075, 1470, 1550, 1850- 1880, 1908, and 2120 nm) were tested. Preliminary studies were performed using fresh porcine renal vessels, ex vivo, with diameters of 1-6 mm, compressed to a thickness of 0.4 mm. A linear beam profile was then applied normal to the vessel for narrow, full-width thermal coagulation. Laser irradiation time was 5 s. Vessel burst pressure measurements were used to determine seal strength. The 1470 nm laser wavelength sealed a wide range of vessel diameters from 1-6 mm. Other lasers (1550, 1850-1880, and 1908 nm) also sealed vessels, but were limited by suboptimal seal pressures, excessive charring, and/or limited power output preventing treatment of large vessels.

Infrared laser sealing of porcine tissues: preliminary in vivo studies

We are exploring infrared (IR) lasers as an alternative energy modality to radiofrequency (RF) and ultrasonic (US) devices intended to provide rapid surgical hemostasis with minimal collateral zones of thermal damage and tissue necrosis. Previously, a 1470-nm IR laser sealed and cut ex vivo porcine renal arteries of 1-8 mm in 2 s, yielding burst pressures < 1200 mmHg (compared to normal systolic blood pressure of 120 mmHg) and thermal coagulation zones < 3 mm (including the seal). This preliminary study describes in vivo testing of a laser probe in a porcine model. A prototype, fiber optic based handheld probe with vessel/tissue clasping mechanism was tested on blood vessels < 6 mm diameter using incident 1470-nm laser power of 35 W for 1-5 s. The probe was evaluated for hemostasis after sealing isolated and bundled vasculature of abdomen and hind leg, as well as liver and lung parenchyma. Sealed vessel samples were collected for histological analysis of lateral thermal damage. Hemostasis was achieved in 57 of 73 seals (78%). The probe consistently sealed vasculature in small bowel mesentery, mesometrium, and gastro splenic and epiploic regions. Seal performance was less consistent on hind leg vasculature including saphenous arteries and bundles and femoral and iliac arteries. Collagen denaturation averaged 1.6 mm in 8 samples excised for histologic examination. A handheld laser probe sealed porcine vessels in vivo. With further improvements in probe design and laser parameter optimization, IR lasers may provide an alternative to RF and US vessel sealing devices.