Virtual surgery aims to replace risky training

Medical students would get their first ‘feel’ for spinal anaesthesia procedures if a new haptically enabled computer simulation system is widely adopted.

Clinical trials of the system are now under way at Cork University Hospital in Ireland and Pecs University in Hungary to explore whether virtual-reality simulations can accurately assess high-risk clinical skills without the need for physicians to practise on patients.

The trials are the culmination of a two-year European Union-funded project, the Medical Competency Assessment Procedure (MedCAP). The programme was designed to decrease spinal procedure injuries, including spinal headaches, cardiac arrest or neurological disorders.

Erik Lovquist, a researcher at Limerick University’s Interactive Design Centre, was in charge of programming the MedCAP simulation system, which uses the Phantom force-feedback haptic device from SensAble Technologies.

The device is a robotic arm, similar in appearance to a miniature construction crane, with a needle in place of the crane grabber.

The entire system can be placed on a work bench and consists of a tilted eye-level 3D computer screen with a mirror beneath it. The haptic feedback device is placed below the mirror. A trainee surgeon, fitted with stereoscopic glasses, can see an image of a patient’s back when looking down onto the mirror.

The moveable robotic arm tracks position and orientation with six degrees of freedom using embedded sensors. It provides feedback forces in three degrees of freedom using motors programmed for different surface tension, friction and viscosity.

A trainee performing a virtual spinal anaesthesia would grab the needle and push or retract it as if they were performing a real procedure. The participant would feel feedback simulating the surface tension that occurs when the spinal needle meets the skin and the ‘pop’ as it punctures the skin. As the simulated needle digs deeper, the participant would feel different viscosities of tissue, ligaments, cerebrospinal fluid and dura mater, the tough outer layer of the meninges surrounding the spinal cord. If the user punctures too far and enters the other meninges or the spinal cord itself, a different sensation will be generated and on-screen error messages appear.

Lovquist worked with physicians to develop algorithms to control the movement of the motors in a way that accurately simulates feedback during the procedure. He said that the system is set up to provide trainees with several different patient cases, including a pregnant woman, an obese person and three types of elderly patients.

The first elderly patient is healthy, the second has mild calcifications in the back and the third has a back that is so calcified that a spinal anaesthesia would be impossible.

These cases are designed to assess whether trainees can perform a procedure for a specific patient or know when to stop.

‘The system should be able to distinguish whether the user is novice, intermediate or expert,’ said Lovquist. ‘The results we get should correspond to what they would do in the operating theatre. So we can go in and say you need to practise on this or you have to change this behaviour and so on.’

He added that surgical interns are currently assessed by honing their skills on a live patient under supervision. The only prior training they had was from a textbook and low-technology simulations that involve sticking a needle in an orange.

The MedCAP partnership includes the Interaction Design Centre, Limerick University in Ireland and the University Graz in Austria, as well as the clinical centres in Cork and Pecs.

After the results are revealed in a few years time, Lovquist claims that the MedCAP team could potentially redesign the system into a new package for commercial sale.

Siobhan Wagner