Cannula

“ Surgeons have long known the danger of permitting air to enter an open abscess. To prevent its entrance they employ a tube called a cannula, to which is attached a sharp steel point called a trocar. They puncture with the steel point, and by gentle pressure they force the pus through the cannula. It is necessary to be very careful in cleansing the instrument; and it is difficult to see how it can be cleansed by ordinary methods in air loaded with organic impurities, as we have proved our air to be. The instrument ought, in fact, to be made as hot as its temper will bear. ”

“ An incision must be made into the left ventricle, and a cannula passed up into the aorta and firmly secured by a ligature passed round the aorta with the assistance of forceps or an aneurism needle. Any blood is cleaned away and the animal is then placed in the water bath for about ten minutes. The tube from the bottle containing the injection fluid is then filled by gentle pressure on the syringe, and clamped when full. Its end is then placed on the cannula and secured there by a ligature. The pressure should be raised by squeezing the syringe until the manometer registers one inch. ”

“ A pilot should be used and care should be taken not to injure the cut ends of the tracheal cartilage. 11. A sterile, bent probe may be inserted downward in the trachea with both cannulae out to excite cough if necessary to expel secretions. An aspirating tube should be used, when necessary. 12. A patient with a properly fitted cannula free of secretions breathes noiselessly. Any sound demands immediate attention. 13. If the respiratory rate increase it is much more likely to be due to obstruction in, malposition of, or shortness of the cannula than to lung complications. ”

“ Thus the valid indications for bleeding are being supplanted by the use of modern drugs that accomplish the same end.
By the twentieth century the lancet was replaced in some quarters by safer devices for removing blood and injecting fluids into the bloodstream. Heinrich Stern improved Strauss’s special hyperdermic needle. In 1905 Stern designed a venepuncture or aspirating needle that was 7 cm long with a silver cannula of 4 cm. Attached to the handle was a thumb-rest and a tube for removing or adding fluids and a perforator within the cannula. ”

“ When the blood is to be given, the delivery tube with the rubber bung is inserted in the flask, and the corpuscles which have gravitated to the bottom are distributed again through the fluid by gently shaking it. In administering the blood, it is very often advisable to inject it through a cannula which is tied into a vein. If the patient is a woman, it will usually be found that the veins are small and buried in fat. Also many transfusions will be given to combat the collapse due to shock and hæmorrhage, in which case the veins will be empty and the use of a cannula will be found essential. ”

“ Injections for the demonstration of blood-vessels, lymphatics, ducts of glands, etc., are rarely used in pathologic work. The organs to be injected must be fresh, warm from the body, if possible. The vessels should be washed out by a freshly filtered 8 per cent sodium nitrate or sodium sulphate solution, followed by physiologic salt-solution. A cannula is introduced into a main vessel, tightly secured, and then connected with a syringe or a gravity injection-apparatus giving a constant pressure. ”

“ See that the piston-rod works properly in the syringe, and that the instrument is fit for use; then place it in the basin of cold water with the cannula to lie till wanted.
Step 2. Place the person supplying the blood on a [Pg 146] couch or easy chair in the same chamber, but so that he cannot see the recipient, lest he faint and his blood consequently flow feebly. Tie up the arm as for venesection; lay ready the lancet, and direct the assistant, in charge of the supplier of blood, to keep his thumb on the vein when it is opened, that the flow may be checked when blood is not required. ”

“ The sanguinary part of the operation begins with the insertion of the cannula to supply artificial respiration. Then the right carotid artery is dissected out. Afterwards, while artificial respiration is being set up, a square opening is made in the left wall of the chest with a knife and the bone scissors. The opening is extended far into the right pleural cavity, and widened downwards till it reaches the diaphragm which is severed from the ribs. It is best to make the opening in the chest large enough to avoid any pressure on the heart from the lungs or other neighbouring parts. ”

“ The objection of the setting of the paraffin in the barrel of the syringe has never hampered any operator, the difficulty in these instances having been entirely due to the obstruction offered its ejection by the threadlike plug obstructing the metal cannula before it; the barrel, being glass, retains its temperature more readily than the thin metal needle, hence the difficulty. ”

“ Bowditch’s system the operator must supply himself with a syringe of a somewhat smaller bore and an intermediate brass piece of a size adapted to fit accurately into the cannula and supplied with a stopcock. By an instrument of this kind the fluid can be drawn off by means of the syringe without any risk of the introduction of ærial germs which always tend to induce suppuration and even a putrefactive decomposition in the contained fluid. ”

“ It is rather an instrument which could be inserted in an incision made by a scalpel, and which could be closed after the abstraction of a certain amount of fluid—the obturator acting as an improvement on the pledget of wool described by Celsus—but otherwise inserted like the previous example. A tube on similar principles to the ascites cannula was employed in empyema (Hippocrates, ii. 259) :
‘After opening let out pus once a day. ”

“ As the intraventricular pressure may rise 150 mm. of mercury in one-tenth of a second, it is no easy matter to contrive an instrument which will respond as rapidly and yet yield an accurate result without overshooting the mark. The final result of a most careful inquiry is the confirmation in almost every point of Chauveau and Marey’s pressure curves. Karl Hiirthles differential manometer has proved to be an instrument of great value and precision. A double-bored tube cannula is introduced so that one tube reaches the right auricle and the other the right ventricle. ”

“ It consists of a graduated glass cylinder, of about 700 cc. capacity, the lower end of which is drawn out into a cannula point at an acute angle with the body of the cylinder; the point is of a size convenient for introducing into a vein and its bore large enough to allow of a free flow of blood through it. Near the upper end is a side tube to which a rubber tube can be attached, and an opening at the top is closed by a rubber bung. An ordinary rubber double-bulb bellows is the only other apparatus that is needed.
[115]
Fig. ”

“ Inside the tubes and surrounding them was a saline solution which was kept at a uniform temperature by a special heating apparatus.
Kennedy had placed the apparatus on the laboratory table and then gently took the little dog from his basket and laid him beside it. A few minutes later the poor little suffering Buster was mercifully under the influence of an anesthetic.
Quickly Craig worked. First he attached the end of one of the tubes by means of a little cannula to the carotid artery of the dog. Then the other was attached to the jugular vein. ”

“ The small amount of blood to be given, 15 cc. per pound of body weight, makes the use of the transfusion flask unnecessary. It is better to use a 20 cc. syringe, into which 2 cc. of a 10 per cent. solution of sodium citrate is drawn as a preliminary. The needle in the donor’s vein and the cannula in the infant’s saphena should each be provided with a rubber connexion, which can be clipped, or pinched by an assistant, when the syringe is not attached. ”

“ Wide-bore needles with short rubber connexions are introduced into the veins of donor and recipient; if, as often happens, this is difficult to do through the skin in the case of the recipient, his vein must first be exposed through an incision and a glass or metal cannula introduced into it. The operator then fills the syringes with blood in quick succession and hands them to his first assistant, who injects the blood into the recipient. Blood is prevented from escaping from the needles when the syringes are disconnected by nipping the rubber connexions with the fingers. ”

“ Harden the latter in Müller’s fluid, decalcify adult specimens in chromic and nitric fluid. Specimens of ciliated epithelium, &c., will be obtained from the lower part, and of the special olfactory epithelium from the upper part. Stain in eosine and hæmatoxyline.
Lungs.—Carefully remove the lungs of a cat without injuring the bronchi or trachea. Introduce a cannula into the trachea and gently inflate the trachea with air. Ligature the trachea and place the lung in Müller’s fluid, a weight being attached to keep the organ submerged. ”

“ As a rule, in taking the Douche with the Fountain Syringe the rubber bag is filled, and suspended from a nail or hook at a height of from two to five feet above the patient, and the fluid passes through the tube by force of gravity, thus requiring no muscular exercise. The force of the stream depends upon the height of the fountain above the outlet nozzle. It is only necessary that the patient should assume a comfortable position where the fluid which comes from the vaginal canal can flow into a water closet, or any convenient vessel. ”

“ Changing the outer tube rarely presents any difficulty because the tissues of the neck soon become matted together, a funnel being thus produced along which the canula is introduced with ease. A new tube should be prepared before removal of the old, and dilators should be at hand for use if the child is frightened, struggles, or coughs: the canula should be introduced quickly and without hesitation, sufficient force being employed to overcome any obstruction. ”

“ Aspirating of blood may mean the puncture of this large vein and it may not be advisable to inject carelessly when this vein has been wounded owing to its size. The crural canal is only about a half inch in length. The injection of it may be accomplished with a hypodermic needle. It is not well to sweep the point of the needle externally with too [Pg 52] great freedom as the vein may be wounded. Inject slowly and move the point of the syringe carefully so that the injection may be diffused in the canal. ”

“ If a vein is struck a second time it will be well to insert the needle through the abdominal wall at the site of the internal ring and if no vein is struck at this point an injection may be made. If this holds the hernia it may be well to make no injection of canal for two weeks. During the interval even if the hernia does not recur it will be well for patient to wear web bandage truss or a spica bandage with a pad pressure over the inguinal canal. At the end of two weeks inject canal moderately with paraffin or vaseline to promote formation of connective tissue. ”

“ Never to allow a nurse, until she be ordered by the doctor, to give either brandy, or wine, or porter, or ale to the patient. (2) I should recommend every respectable monthly nurse to carry about with her an india-rubber vaginal syringe. One of the best for the purpose is Higginson’s syringe, [84] which is one constructed to act either as an enema apparatus, or, by placing the vaginal pipe over the enema pipe, as a vaginal syringe. She will thus be armed at all points, and will be ready for any emergency. It is an admirable invention, and cannot be too well known. ”

“ It is brought forward more as a caution to the young than as a reflection on the senior members of the profession. Some patients have recovered from the operation, and lived in misery for months and years, passing their urine through a canula retained in the wound. An incision is made above the symphysis pubis, in the mesial line, dividing the integuments and cellular tissue, to the extent of from one to two inches; on thus exposing the coats of the bladder, a flat trocar with a canula is pushed into the cavity of the viscus, at the lower part of the wound ”

“ I then introduced a trocar and canula, and drew off fifty ounces of pus, slightly tinged with blood. I re-adjusted the compresses and bandage over the sinus, hoping that a part of it at least would become obliterated before it became necessary to open it more freely.
Feb. 15th, 5 p.m.,—pulse 112, temp. 102.5. The inflammation [Pg 13] over that part of the sinus to the right of the spine is still about the same as yesterday; also that over the left ilium. The fluid has increased during the last twenty-four hours so that there is now nearly as much as was drawn off through the canula yesterday. ”

“ A Thudicum douche-bottle or a fountain syringe can easily be used by patients themselves as often as is required. The orifice and the tubes should be protected by thorough and rigid antisepticism. As the case improves the cavity gradually gets smaller, the two pleuræ become adherent, and the quantity of fluid lessens until only a small amount flows out. Every eight or ten days we carefully draw out the tubes by degrees, until we have only a little canal beneath the walls. We can thus let the orifice heal slowly, for the sac is obliterated and the patient cured. ”

“ It allows the fluid to be drawn out with a uniform and feeble aspiratory force. The flow is very slow, which gives the lung time to expand gently, and the displaced organs to return gradually to their normal position. With the manometer attached we can judge accurately as to the intra-thoracic pressure. The size of the canula has to be larger than when we employ the aspirator—4 mm.—whereas with the latter we use 1⁄2 mm. or 1 mm. in diameter. If by any accident the lung should be perforated, the larger orifice would not be as harmless and insignificant as the smaller one. ”