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Infrared lasers may provide an alternative to conventional radiofrequency and ultrasonic devices for hemostatic sealing of vascular tissues during surgery. This study explores UV light induced fluorescence from blood vessel walls as a potential non-destructive optical feedback method for indicating successful laser seals. A light emitting diode (LED) with center wavelength of 340 nm and 0.1 mW power was used with a Y-shaped fiber bundle, composed of seven 200-μm-core fibers. The central excitation fiber was split and connected to the LED, while the detection ring of six fibers was connected to a spectrometer. A long-pass filter with 360 nm cut-on wavelength rejected diffusely reflected excitation light. The 7-fiber bundle was aligned with porcine renal arteries compressed between optical windows to simulate placement between laparoscopic sealing device jaws. The fluorescence spectrum was acquired before and after sealing vessels (diameter = 3.0 ± 0.6 mm) with a 1470 nm diode laser for 5 s using incident powers of 30 W (sealing, n = 10) or 5 W (control, n = 10). The tissue fluorescence signal increase in 470-520 nm spectrum using 1s integration times was correlated with vessel seal strengths using industry standard destructive vessel burst pressure measurements. The integrated fluorescence signal increased 71 ± 25% at 30 W (sealing) versus 19 ± 14% at 5 W (control) (p < 0.05), corresponding to successful vessel seals averaging 639 ± 189 mmHg versus failed seals averaging 39 ± 41mmHg (control) (p < 0.05). The increase in tissue fluorescence signal during laser vessel sealing may provide a non-destructive optical method for indicating hemostatic seals. Future work will focus on performing real-time measurements and integrating the fiber optic bundle into the upper jaw of a laparoscopic device.
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