Coagulation is an essential component of brain tumor resection. Permanent coagulation of smaller and larger hemorrhages keeps blood loss low, reduces the risk of secondary bleeding, and keeps the surgical field clear. Coagulation can also be used for tumor shrinkage. For resection, the ultrasonic aspirator is usually suitable, especially for debulking large tumors, but bleeding that occurs, requires frequent changes of instruments. This instrument change is time consuming and interrupts the workflow. Our preliminary investigation revealed that during tumor resection with the ultrasonic aspirator, the surgeon must change the instrument every 60 seconds on average to stop occurring bleeding. Typically, bipolar forceps are employed for this purpose. To address these circumstances, a 1940 nm thulium laser was integrated into an ultrasonic aspirator for contactless coagulation.

The 1940 nm thulium laser is suitable for CNS tissues due to its wavelength-specific water absorption. The laser fiber used has a diameter of 400μm and is additionally cooled by a CO2 flow of 2 l/min. The laser fiber was integrated into the ultrasonic instrument [DB1] using a special adapter. Both instruments could be triggered via a double foot switch. Between February 2022 and November 2023, 12 patients with diagnosed brain tumors were enrolled in a clinical pilot trial. We evaluated the use of a laser-ultrasonic aspirator combination instrument during standard tumor resections regarding efficiency and safety. The surgeons had four different settings available for different levels of bleeding. From 15 watts, 100ms pulse duration at 5Hz to 15 watts 400ms pulse duration at 1Hz, 15 watts cw (continuous wave) and 30 watts cw.

We found that laser integration offers advantages in the workflow, especially for diffuse venous bleeding. Bleeding could be stopped precisely and with sufficient efficiency. The operating concept was perceived as simple. However, most users preferred the bipolar forceps for stopping more severe arterial bleeding.

Nevertheless, there are great advantages in the workflow, especially when debulking large tumors. The combination instrument of ultrasonic aspirator and laser offers a considerable advantage in the case of diffuse venous bleeding in smaller vessels. There were disadvantages when stopping arterial bleeding in larger vessels. Here, the use of bipolar forceps is advantageous, also due to the mechanical effect on the vessel during coagulation.