Physical effects of shock waves on the kidney. A commentary based on several experiments

An egg can be an excellent experimental model for it provides us with accurate information on the effects of shock waves on biological structures of acoustic impedance identical to that of human cells and interfaces of small width. The authors divided the experiments into two groups. The one in which the shock wave was focused on the whole egg--its shell is almost transparent to shock waves--showed that hyperpressures on thin interfaces have hardly any destructive effect, whereas in the other in which the egg was used without the shell and the shock wave was directed to the yolk, yolk fragments were thrown into the surrounding water, indicating that destructive effects are caused by the cavitation effect. The authors suggest some penetration ranges of shock waves on the kidney which they consider to be the least harmful.