In bringing the screw action on the stone into play, a wheel is usually provided (Fig. 52), which is grasped between the index finger and the thumb.
The more powerful lithotrites of Bigelow are fitted with a ball handle (Fig. 53), and rotation is thus effected, though I prefer the wheel movement. With the former, I have no doubt, greater power can be obtained, but at the sacrifice of some delicacy in manipulation. Knowing what the fenestrated instrument with the wheel is capable of accomplishing, I question, in the case of a stone requiring greater force than this, whether, with possibly some exceptions, it is pru dent to select lithotrity under such circumstances unless provided with considerable practical experience. Lithotrites are made of the following sizes (English gauge) : We cannot be too careful in the selection of these instruments, when we consider the strain that is put upon them and the damage that might be occasioned by their bending or breaking. The best material and workmanship should be required. Upon this point Dr. Keegan" remarks : " I would warn the inexperienced against the fatal economy of buying cheap, and therefore badly made and untrust worthy, lithotrites. There are plenty of such instruments in the market, and they may prove, even in skilled hands, most dangerous weapons of destruction." Care should also be taken by the operator in seeing that all the movements of the lithotrite are without hitch or friction, so that noth ing may intervene between his sensation of touch and the stone. The smaller the calculus or fragment the greater is the necessity for this accuracy in adjustment. Further, it must be ascertained that the outer blade well protects the inner one, especially where the stone is seized and the two parts of the instrument are made to approximate. These are points among others which the surgeon should himself attend to and test in selecting his lithotrites. It is well for the oper ator to be provided both with fenestrated and smooth-bladed instru ments, as the latter are very useful, especially in the case of soft stones or small fragments. All lithotrites are liable to become im
pacted with debris; generally speaking, by reversing the screw action and giving the instrument, whilst firmly held, one or two sharp taps with a concussor of some kind, the hitch is overcome. It is seldom that the impaction is of such a nature as to render the closure of the blades impossible. Mr. Cadge has informed me that such an occur rence once happened in his practice. In using a lithotrite for meas uring a stone in a male child, with the view of ascertaining whether it could be crushed, ou seizing the calculus and lightly closing the blades upon it, he found to his astonishment that the instrument, though one of the best of its kind, was absolutely locked. He could neither close uor open it, and no force he could safely apply being of any avail, he performed a supra-pubic cystotomy on the end of the lithotrite, and by protruding it was able with his finger to clear the instrument from the debris which had impacted it, the patient making a good recovery.
The stone having been broken into fragments by one or more in troductions of the lithotrite, the debris is removed by means of a large eyed catheter and a syringe or aspirator filled with water. The ca theters for this purpose are of two kinds, straight and curved. The largest I employ corresponds with No. 26 of the French gauge, and from this sizo they gradually diminish until we come to those appro priate for children. The eyes of my evacuators (Fig. 54) are rather larger than those in general use. It is very necessary that all these instruments should be provided with a stylet (Fig. 55) so that they may not become impacted with fragments. If an evacuating catheter is withdrawn with a sharp fragment retained in the eye, the urethra may be wounded and much damage done. If there is the slightest resistance on attempting to withdraw the instrument the stylet should be at once passed. Bigelow preferred a straight evacuator. They are almost as easily introduced as curved ones, but the latter are generally used.