Multifunction Robotized Surgical Dissector for Endoscopic Pulmonary Thromboendarterectomy: Preclinical Study and Evaluation

Patients suffering from chronic severe pulmonary thromboembolism need pulmonary thromboendarterectomy (PTE) to remove the thrombus and intima located inside pulmonary artery (PA). During the surgery, a surgeon holds tweezers and a dissector to delicately strip the blockage, but available tools for this surgery are rigid and straight, lacking distal dexterity to access into thin branches of PA. Therefore, this work presents a novel robotized dissector based on concentric push/pull robot (CPPR) structure, enabling entering deep thin branch of tortuous PA. Compared with conventional rigid dissectors, our design characterizes slenderness and dual-segment-bending dexterity. Owing to the hollow and thin-walled structure of the CPPR-based dissector, as it has a slender body of 3.5 mm in diameter, the central lumen accommodates two channels for irrigation and tip tool, and space for endoscopic camera's signal wire. To provide accurate surgical manipulation, optimization-based kinematics model was established, realizing a 2-mm accuracy in positioning the tip tool (60-mm length) under open-loop control strategy. As such, with the endoscopic camera, traditional PTE is possible to be upgraded as endoscopic PTE. Basic physical performance of the robotized dissector, including stiffness, motion accuracy, and maneuverability, was evaluated through experiments. Surgery simulation on <i>ex vivo</i> porcine lung also demonstrates its dexterity and notable advantages in PTE.