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Biomedical subjects

C G Cao

Publications and source records attributed to C G Cao.

7 recordsLinked to original sources
PubMed1999

Gaze patterns in laparoscopic surgery.

By understanding surgeons' patterns of gaze, and what visual information is being obtained during a procedure, one can improve the operation via new techniques or instrumentation. Part of a larger project on Remote Manipulation in Endoscopic Surgery, we analyzed eye patterns of surgeons from videotape annotation. Three categories of eye patterns were defined: 1) eyes on (gaze on monitor); 2) eyes down (gaze on external operative space); 3) eyes off (gaze away from monitor/hands). In the context of hierarchical decomposition of procedures we compared eye patterns and sequential dependencies (gaze as a function of previous gaze) by procedure, surgical steps and tasks. Timelines showed transitions in eye patterns during the procedure. We determined what visual information is available and what visual information is needed by the surgeons. By comparing these, we suggest technology that can provide these needs.

Feedback↗
PubMed1999

Virtual hand laboratory meets endoscopic surgery.

We describe two recent research projects: the Virtual Hand Laboratory, and Remote Manipulation in Endoscopic Surgery. The Virtual Hand Laboratory (VHL) is a prototype experimental tool for investigating human visuomotor coordination for object manipulation in augmented and virtual environments. The Remote Manipulation in Endoscopic Surgery (RMES) project examined surgeon's use of viewing and manipulating technologies in laparoscopic surgery, both in clinical and experimental settings. Current research brings together these two parallel research projects (VHL and RMES), for applications in planning and real-time execution of surgical procedures as well as for surgical training. We outline our research directions and detail current activities on superposition of display space on the workspace for the surgeon's hands.

Endoscopy↗
PubMed1999

Hierarchical decomposition of laparoscopic procedures.

The purpose of this report is to outline the hierarchical decomposition of surgical procedures, from surgical steps through tasks and subtasks to tool motions, and highlight implications for surgical training systems. Three common laparoscopic procedures were analysed: cholecystectomy, inguinal hernia repair, and Nissen fundoplication. In laparoscopic training workshops and operating rooms, our observational research included split screen videotaping of both the endoscopic view and our video camera's view of the primary surgeon. Videotapes were extensively annotated and analysed to yield timelines of each procedure, with component surgical steps, substeps, tasks, and subtasks duration as a function of procedure. The hierarchical decomposition of surgical procedures provides a framework for structuring a systematic approach to training, in the real and simulated environment. An example comparing variations in the fundoplication procedure is presented. Our results also have important implications for the design and assessment of new technology and intelligent tools in endoscopic surgery.

Cholecystectomy, Laparoscopic↗
PubMed1992

Testosterone fails to rescue motoneurons from axotomy-induced death in young rats.

This study was undertaken to determine whether testosterone acting on muscle alone could enhance motoneuron survival after axotomy. Facial nerves were transected unilaterally in 10-day old rats in which androgen receptors were already present in skeletal muscle but not yet developed in motoneurons. Testosterone treatment lessened chromatolysis but failed to reduce neuronal loss which reached more than 50% 2 weeks postaxotomy. The inefficacy of testosterone was attributed to the death of motoneurons before they could re-establish synaptic contact with targets, thereby rendering target-derived trophic substances stimulated by testosterone unable to rescue motoneurons in a timely manner. The present finding is consistent with our hypothesis that functional neuromuscular connectivity is a prerequisite for testosterone to promote neuronal survival.

Animals↗
PubMed1991

Muscle as the primary site for testosterone to promote survival of axotomized motoneurons.

Whether the effect of testosterone to promote neuronal survival is expressed through its interaction with motoneurons or with effector muscles was investigated, since androgen receptors are present in both tissues. Following unilateral transection of the hypoglossal and facial nerves, hydroxyflutamide, an androgen receptor antagonist, was injected into the tongue muscles to block androgen receptor binding during the period when rats were treated with testosterone. The results indicate that hydroxyflutamide abolished testosterone effects on the hypoglossal but not the facial motor nucleus, indicating that androgen receptors in effector muscles are the primary mediators of hormonal actions. We postulate that testosterone may play a role in the production of muscle-derived factors which promote the survival of injured motoneurons.

Anesthesia↗