A tube has to be worn afterward; this is put into the opening, and fastened in by means of a strap or tape passed round the neck. There are many tubes sold by the instrument makers for this purpose; the majority, however, are far too large. None should be beyond one inch in diameter. The horse only requires to inhale part of the air through the canula, the remainder coming, as before, through the larynx. A free space of one inch is, therefore, plenty to admit the deficient oxygen; for no animal could live through an operation, were air, previous to its commencement or during its continuance, altogether excluded.
MR. T. W. GOWING'S TRACHEOTOMY TUBE.
A. The canula, with a shifting shield, armed with the pointed trocar.
B. The trocar withdrawn from the canula, showing its peculiar construction.
C. The canula fitted into the horse's trachea, showing how the movable shield may be adapted, by means of a screw, to the size of the horse or the swollen condition of the parts.
The best instrument for hasty and temporary tracheotomy is the invention of Mr. T. W. Gowing, of Camden Town. To insert this canula no cartilage need be excised; a puncture is made with a knife through the connecting medium of the tracheal rings, and through this puncture the tube is driven. It is of all use for temporary or immediate service, but obviously would not do for a continuance.
The objection to tracheotomy, when designed to last for any period, is that the canula, by irritating the lining membrane of the larynx, is apt to provoke abscess, which impedes the breathing to a degree that destroys the life. The author has seen some fearful instances of this effect; but of all tubes, that invented by the French seems to be least open to this objection.