Laser tissue welding: a new device controlled by reflectance

Laser tissue welding is used to close wounds or to anastomose conducts such as arteries. The welding effect is due to tissue denaturation which depends on the irradiation parameters. An excessive laser irradiation leads to irreversible thermal damage. In conventional welding procedures, laser irradiation is controlled by visual inspection of the welded zone. A new device based on an 800 nm diode laser allowing an automated welding procedure is described here. The device measures the variation of the diffuse reflectance on the treatment area and stops laser irradiation when a given optimal value is reached. This allows the user to increase the reproducibility of the treatment by avoiding the subjective aspect of welding completion assessment by visual criteria. The system has been tested by in vitro welding an egg yolk membrane on mesenteric bovine arteries. The results have shown that for a given laser power, there is a specific reflectance decrease threshold value leading to an optimal welding. Reproducible welds with minimal thermal damage could be obtained.

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