A measure of scalpel skills

August 27, 1999

Surgeon Ara Darzi is developing ways to test the dexterity of his theatre peers. Geoff Watts reports.

Step aboard a commercial airliner and you can be certain that the skills of the pilot flying it will have been tested fairly recently, either in the air or inside a cockpit simulator. Lie on a trolley to be wheeled into the operating theatre, and you know that the surgeon soon to be plunging a knife into your body

The sentence is best left unfinished because the parallel with airline pilots cannot be drawn - yet. But Ara Darzi, professor of surgery at Imperial College School of Medicine, is confident that the periodic scrutiny of surgical skill will eventually happen.

"Politically this is a hot potato, but I have no doubt that in years to come each surgeon will be individually assessed, whether for manual dexterity or whatever. This is where the General Medical Council and the Royal Colleges are heading."

The findings of the heart surgery inquiry now taking place in Bristol will no doubt add to that pressure. If Professor Darzi is correct, and dexterity is one of the criteria used to check up on surgeons, the chances are that something like the system he has been developing will feature in that assessment.

It was not, in fact, a particular interest in the reaccreditation of surgeons that prompted Ara Darzi to become involved in this research. Some four years ago he began trying to compare the performance of surgeons using three as opposed to two-dimensional images when performing keyhole surgery.

Operations of this kind are done not under direct vision but by viewing the instruments, inside the body, on a TV screen. Like any 2-D image, the pictures lack depth, and computer engineers have been trying to develop a 3-D alternative.

To find out if the extra dimension makes a worthwhile difference, Professor Darzi and his colleagues began developing what he now calls ICSAD: the Imperial College Surgical Assessment Device.

In essence, ICSAD equates manual dexterity with economy of movement. Unobtrusive sensors attached to the surgeon's hands (or, in the case of keyhole surgery, the instruments) record the distance they move, their speed, the number of their movements and the time required to perform either a real or a simulated task. A computer tots up the scores.

This gives a quantitative value for the skill with which surgeons move and use their hands. But a skilful cut has no value if made in the wrong place on the wrong organ. To judge this, you need video images of real surgery.

Originally these had to be assessed by other experienced surgeons. Now, using digitised video images, even this qualitative assessment can be handled by the computer.

To validate the system, the researchers compared the performance of experienced surgeons, trainees and medical students. The differences between the groups, both quantitatively and qualitatively, were - fortunately for us as well as them - clear and significant.

Having devised a system that could measure surgical dexterity objectively, Professor Darzi began to think of ways to apply it.

As an academic clinician involved in teaching a basic skills course run by the Royal College of Surgeons, he had an obvious interest in finding out if what they were doing actually worked. So he asked trainees to use the instruments of a keyhole surgery simulator to perform an odd but simple task: grasping chickpeas and placing them on the heads of golf tees.

The training markedly improved the candidates' scores, suggesting that it was indeed improving their psychomotor skills.

He has since gone on to mount even more imaginative experiments. The effect of fatigue, for example. Arguments about the impact of sleep-deprivation on doctors' performance have been raging for years, mostly without any hard data.

Professor Darzi and colleagues have used ICSAD to measure the dexterity of trainee surgeons between six and seven in the evening, and then again between eight and nine the following morning. During the intervening night they were variously allowed to sleep undisturbed, or to sleep between periodic disturbances (simulating the reality of being on call), or were kept awake the whole night. The findings support what most of us would already hope for on grounds of common sense: that is, to have our hernias repaired and our heart valves replaced by surgeons who have enjoyed a good night's sleep.

Music is the factor currently under scrutiny. Many surgeons like listening to it while they operate. Ara Darzi is aiming to find out if music does boost their dexterity - and, if so, what sort might be most beneficial.

Sadly, the appealing notion that a childhood spent playing computer games might turn out to be a useful preparation for the demands of keyhole surgery finds little support. Surgeon Simon Smith, a research fellow working with Professor Darzi, describes a study in which "championship" level games players were matched against surgeons and medical students in performing a computer simulation of a simple surgical task. The surgeons were more careful, more efficient - and faster.

As for the question that first prompted Professor Darzi to investigate objective measures of dexterity, he is now in a position to answer it. Surgeons doing keyhole operations do perform better if the TV image on which they rely to see what they are doing is in 3-D.

The Imperial College group is keen to stress that manual dexterity is only one requirement of a good surgeon. But that is probably not how the public see it. So, in ten years' time, expect another government league table, this one for individuals: the surgical skills index.

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