New York, March 20 (IANS): The expanding waistlines of the citizens, increasing stress and humid conditions may have given rise, at least in part, to rising incidence of kidney stones in the world, but a way to ease the treatment of the disease has eluded the scientists for some time.

This is likely to change soon as engineers from Duke University in Durham have devised a way to improve the efficiency of lithotripsy - the medical procedure of demolishing kidney stones using focused shock waves.

After decades of research, all it took was cutting a groove near the perimeter of the shock wave-focusing lens and changing its curvature, the engineers said.

“We’ve developed a simple, cost-effective and reliable solution that can be quickly implemented on their machines,” said Pei Zhong, professor of mechanical engineering and materials science at Duke University.

In laboratory tests, the researchers sent shock waves through a tank of water and used a fiber optic pressure sensor to ensure the shock wave was focusing on target.

They broke apart synthetic stones in a model human kidney and in anesthesised pigs and used a high-speed camera to watch the distribution of cavitation bubbles forming and collapsing - a process that happens too fast for the human eye to see.

During the past two decades, lithotripter manufacturers introduced multiple changes to their machines, but they couldn't improve effectiveness of kidney stone treatment.

While the current commercial version reduced 54 percent of the stones into fragments less than two millimeters in diameter, the new version pulverised 89 percent of the stones while also reducing the amount of damage to surrounding tissue.

The study appeared in the journal of Proceedings of the National Academy of Sciences.