enters the cavity, we prevent the point from pricking the lung. So small an orifice is made that even if the needle does touch the lung, there is no danger, for the orifice closes over at once. As Dieulafoy claims, "the fineness of the needle guarantees the harmlessness of the puncture." Castraux's concealed point (invented in 1873), and Fitch's (of Nova Scotia) protected canula (invented in 1873), are valuable additions to the aspirator-needle. These dome-trocars, as they are called, prevent the possibility of injuring the lung, for the sharp-pointed needle, after it has penetrated the pleural cavity, is at once, by a slight movement, converted into a blunt-pointed needle with an orifice near the end. With these very fine needles the force is sufficient to draw up the thickest fluids We are compelled to admit that Dieulafoy's instrument is a great advance on any other that has been invented. Its simplicity, its easy application, its safety, have rendered paracentesis a harmless operation and one of great value in serous effusions. While Guérin and Wyman may both claim priority of invention, all must admit that Dieulafoy has improved upon their ideas and given us a beautiful and effective instrument. There have been proposed, since Dieulafoy showed his instrument in 1869, no less than forty other aspirators, modifications in form or dimensions of his apparatus. Of these, to us the most valuable is Potain's bottle aspirator, with which aspiration can be so easily and effectually employed. It is simple and cheap. An india-rubber cork accurately fitting a strong bottle is perforated for two tubes each having a stopcock. One of the tubes fits on the end at the exit in the basin, and the other is adapted to an aspirating syringe. One of the most important of the improvements to the aspirator-canula is the addition-first suggested in 1858 by Charles Thompson,' and afterward adopted by Potain, Powell, and Fraentzel-of a lateral tube for the outflow connected with the main canula through which the trocar passes. By this improvement, in case the canula is clogged up, the trocar can be pushed down to remove the obstruction without danger. The principle of aspiration is now well established, and the indications for its use are becoming more defined and more accurate. New applications as a means of diagnosis, as well as of treatment, daily render it more valuable. To guard against the dangers shown by modern experience to be sometimes attendant upon the operation of aspirating the pleura (see Dangers of Thoracentesis), it is now generally admitted that the removal of the contents of the chest should be slow and gradual; and that, ordinarily, it is safest at one operation to remove only a portion of the effused liquid. Our object should be to remove pressure and allow nature by absorption to take away the remainder, for positive pressure is an urgent indication for thoracentesis. It is therefore of primary importance to properly estimate the quantity present, and thus to test the intra-thoracic pressure. Great care and caution must be used, because if we extract too much the operation may be followed by serious results." Large-sized canule should never be used, for fear of too rapid withdrawal of fluid. It has been demonstrated that even with a capillary perforated needle we can exercise more negative pressure than is safe, especially toward the close of the operation, when there supervenes a negative pressure exerted by the fluid remaining in the pleural cavity. It is from these well-known facts that we recognize the great value of Potain's ingenious addition to the aspirator of a manometer of extreme simplicity, a kind of barometer or cuvette, which is placed along the tube which withdraws the fluid. If we are not satisfied with this new safety improvement of the aspirator, we may adopt Douglass Powell's suggestion (On Consumption, 1 Med. Times and Gazette, 1858. 2 Trans. de l'Assoc. pour l'Adv. des Sciences, 6th Session, 1877. etc.) of fitting into the bottle a pressure-gauge, so as to know at any moment what degree of aspiration is being used. The syphon method has been of late years very extensively used, especially by Southey, W. H. Stone, and Garland, A. T. H. Waters, Wilks, Oxley, and habitually by Douglass Powell. It is a feeble aspirating force, which has very decided advantages. It is effective, and acts slowly and uninterruptedly with a gentle and uniform negative pressure. Its action allows the lung. gradually to expand and the displaced organs slowly to resume their normal position. It thus in many cases furnishes us with a safe means of thoracentesis. (See Surgical Treatment, in Pleurisy.) |