CHAPTER XXIV

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ASEPSIS AND ANTISEPSIS; TREATMENT OF WOUNDS.

The medical student of the present generation has no conception of the contrast between the results of today and those of a generation ago, or before the introduction of antiseptic technique and its later perfection, asepsis. Under the term “_antiseptic_” should be included those measures intended to combat sepsis, or surgical infection, from without. The term _asepsis_ is of later date, and was introduced when it was found that the prevention of infection was better than measures calculated to overcome it, or atone for its presence. A perusal of former surgical horrors will afford but an insufficient comparison as to the incalculable benefits for which we are indebted to a small group of men, of whom Lister is the most important; although the names of Pasteur and of Ogston should ever be held memorable in this connection. The two great nineteenth century achievements in surgery were anesthesia and antisepsis, both of Anglo-Saxon origin, one American, the other British.

It was the recognition of the parasitic, _i. e._, the germ nature of surgical infections, which led to Lister’s first attempts to exclude and combat the infecting agents. And while the original technique which he introduced has been changed in nearly every particular, the correctness of the views upon which it was based has been ever broadened and strengthened. We have learned that simple measures may be as effective as those more complicated, and the principal changes which have been made in three decades have tended toward simplicity and prevention. Thus heat has been made to take the place formerly occupied by carbolic acid. And we have learned that parts made clean need little antiseptic protection. We have learned that healthy tissues are endowed with large powers of self-protection, and also that this self-protection is interfered with by causes over which the surgeon has sometimes but little control. _A wound in a body loaded with toxic products is by no means protected against infectious agents by mere external agencies._ The appearance of pus in a wound is a reflection upon the surgeon. The ideal aseptic technique will include many days of local and constitutional protection, as has been stated in the sections on Auto-intoxication and on the Preparation of the Patient.

The methods of either antiseptic or aseptic technique include as a fundamental basis the necessity for perfect sterilization of everything which may come in contact with the wound, so far as the surgeon can control it. The atmosphere contains in suspension bacteria, but their contact is no longer dreaded, because of reliance upon the germicidal powers of the fluids and tissues of the body. It is known, however, that in accumulation of fluids there is danger as well to the tissues, either from rude handling, application of large pressure forceps, the insertion of too many stitches, or whatever else may lacerate or impair the circulation.

There are parts of the body where no precautions can afford complete freedom from germ activity, as in the mouth, the vagina, the rectum. Here the surgeon must be cleanly in his work, assuring himself that he introduces nothing new from without. Furthermore, after operation upon these parts he must ensure his precautions by the use of mouth-washes, douches, etc. On the other hand, ample opportunity should be afforded for sterilization of the field of operation, of the hands of the operator and his assistants, the instruments, ligatures, and dressings--everything which may come in contact with the raw surface.

_Heat_, moist or dry, is the simplest of all sterilizing methods. It is used in dry and in moist form. The most resistant spores are those of anthrax, which is supposed to be a laboratory germ, one not seen in practice. Most of the imported catgut is made from the intestines of sheep, and sheep die frequently (on the Continent) of anthrax; it will thus be seen that the danger of an anthrax infection is not so remote as might first appear, and that no precautions are sufficient which do not include a degree of heat and length of exposure sufficient to kill these germs. In the operating-room, as in the laboratory, has been introduced the method of “fractional,” _i. e._, _repeated sterilization_. Most of the materials thus exposed may be left in superheated steam under pressure from thirty to sixty minutes. They are then exposed once or twice more to the same heat at intervals of twenty-four hours. In order to make heat thoroughly useful its effects should permeate everything which it is expected to so sterilize; hence the addition of steam _under pressure_, especially when dressings, towels, etc., are folded. It is well to have a form of sterilizer that permits steam to be turned off and drying to be accomplished slowly by the aid of dry heat.

Next to steam thus utilized is _boiling water_, in which nearly everything can be sterilized. Silk sutures and silkworm-gut may also be sterilized in this way; animal suture does not permit of it unless previously hardened. The effectiveness of boiling water is increased by adding to it 1 per cent. of sodium bicarbonate, by which its boiling point is raised.

Dry heat is employed in an oven, or its equivalent, preferably in some apparatus by which temperature can not only be measured but maintained. In such a mechanism it is well to have the temperature raised to 300° F. for at least half an hour, and then let its contents cool slowly.

Another method of sterilization is by using _volatile_ or easily volatilized _chemicals_, such as formalin in its fluid form, or its equivalent called paraform, which comes in crystals or may be had in tablets ready for use. Formalin is a powerful bactericidal agent, and if used in such form as to be sure of its penetration, good results may be expected. Some materials and instruments which are injured by steam or dry heat may be kept in an atmosphere of paraform, or sterilized by exposure to formalin vapor, being then subsequently protected against exposure in a sealed package. Catheters which have been boiled or cleansed can be thus exposed, as Hutchings has shown, and can be regarded as safe for use. They can, moreover, be resterilized in the same way. Naphthalene has similar properties, but is not quite so strong. The writer is accustomed to use one or the other of these in jars or receptacles containing dry dressings, catheters, and rubber gloves.

If aseptic methods are practised there will be but little use for the employment of any antiseptic, either in solution or in any other form.

Boiled water and sterile salt solution should be available for all purposes. It is customary, however, to have a solution of mercuric chloride on hand, which is colored in order that it may not be mistaken for any other, in which to rinse the hands, especially after they have been in alkaline solution.

The first thing to be sterilized should be that part of the body upon which operation is to be made. In some cases, as about the feet, the mouth, etc., this preparation should be begun two or three days beforehand; in other cases twelve to twenty-four hours will suffice. Preparation should be begun with soap, nail-brush, and razor, the parts being thoroughly cleansed and shaved. It is then customary with most operators to keep a moist and antiseptic dressing applied upon surfaces thus cleansed, which should be protected from drying by a covering of oiled silk or rubber tissue. Green soap is usually employed, which may have added to it a small percentage of carbolic acid or lysol. The mercurial preparations are too irritating to the skin. Carbolic acid has the reputation of being absorbed rapidly. On tender skins and in certain parts of the body it is impossible to make such applications, especially of soap poultices. Under these circumstances repeated washings and some protection should be practised. Feet upon which operations are to be made should be soaked repeatedly and scrubbed. Twenty-four hours previously to operating on the head the scalp should be shaved--preferably forty-eight hours--and prepared as above. For operations in the mouth the tooth-brush and antiseptic mouth-washes should be frequently used. For those in the vagina, douches, etc., should be frequently administered.

The preparation of the field of operation includes a final scrubbing, with a washing of alcohol or alcohol and ether. The hands and external clothing of the surgeon and his assistants should be sterilized, also the towels, suture materials, instruments, and dressings.

Lawson Tait was the first to teach the great value of absolute and mere cleanliness. This applies in large degree to the hands of the chief operator and of the assistants. With a large amount of scrubbing and cleansing of the hands it is not possible to put them into a condition of ideal sterilization. This is perhaps more true of the hands of some than those of others. A realization of this fact has led to the introduction of _gloves_, either thin rubber or cheap cotton. The former may be used repeatedly. The latter are sterilized by repeated boiling and may then be used again. Rubber gloves may be sterilized by steam or boiling water, and may be cleansed with soap and water or one of the stronger antiseptic solutions. The introduction of rubber gloves has brought great improvement in results. The gloves, however, constitute an impediment to some of the finer work and the easy recognition of tissue. Not the least important of the advantages of rubber gloves is the protection they afford to the surgeon’s hands and to other patients. Many accidental infections may be saved the operator if his hands can be kept out of pus, while the use of gloves permits the operator to pass from a pus case to a clean one without exciting fear. A snugly fitting glove is best drawn upon the dry hand by the aid of sterilized talcum. But the hand which it encloses should have been previously thoroughly sterilized so that it will not be a source of danger should the glove be pricked or torn. The operator can keep his hands in more favorable condition by using gloves dry in this way than by macerating his hands inside of wet ones.

_The question of hand sterilization_ is an important one, whether the gloves are to be worn by some or all of the operating staff. There are occasions when it is important to make the hands absolutely clean because no gloves can be procured. Even the hands encased in gloves should be thoroughly prepared, as there is no knowing when the glove may tear and the surgeon’s bare hand come into contact with the patient’s tissues. Running water is preferable to a basin filled with it, for while it runs it carries away such material as may be detached by soap or nail-brush. If it be not possible thus to wash the hands, then repeated basins of sterilized water should be used, and all the crockery or metal ware used in the process should be sterilized, so that the hands will not be contaminated by handling unsterilized material. Nail cleaners are essential agents, to be vigorously used, and nail-brushes should be sterilized after each using, and there should be a separate brush for each operator. The common soaps and even the officinal green soap are not sterile. The former should be relied on only for the first cleaning, and the latter should be sterilized before use. A dirty hand should not be thrust into a receptacle containing freshly sterilized green soap. The outside coating of dirt should first be removed by an ordinary soap. Vegetable fiber has been recommended by many, but it is not as good as ordinary corn-meal, which should be sterilized before using. It is not as gritty nor as keen as sand, and yet it is sufficiently rough to serve admirably the purposes of a curry-comb. A first scrubbing with common soap and a nail-brush, followed by green soap with corn-meal, and this by a thorough use of the nail cleaner and a clean nail-brush, will ordinarily serve to put the hands in a reliable condition. It is the practice of some to add antiseptics to the soap, _e. g._, lysol and thymol. A number of years ago I introduced ordinary _mustard flour_ for this purpose, basing its use upon the fact that the essential oil of mustard is one of the most potent of the vegetable antiseptics, in addition to its power as a deodorizer. (Parenthetically it may be said that when unpleasant odor attaches to the unprotected hands after making a postmortem examination, or opening an offensive collection of pus, the use of mustard will quickly remove the taint.) Even mustard is not absolutely reliable, nor is anything else which can be tolerated by the human skin. A method much in vogue a few years ago was to wash the hands in a solution of potassium permanganate, and then to decolorize the skin in another strong solution of oxalic solution. This method was at one time regarded as an effective one, but it is severe upon the skin. Another method in use at present combines commercial chloride of lime with saleratus; here free chlorine is supposed to be the active agent.

The bacteriological side of this subject has been investigated by numerous observers, particularly Dr. E. R. McGuire, attached to the Buffalo Surgical Clinic, who reached the following conclusions: Absolute sterility of the hands is unattainable, but as toward this result nothing takes the place of long and vigorous mechanical scrubbing under aseptic precautions; the use of antiseptics on the skin is of questionable value and often distinctly harmful; the operator whose hands perspire freely should wear gloves in every case; the use of rubber gloves is not ideal, but gives the nearest approach to it.

No material should be used which is so harsh that it will injure or destroy the epithelial cells either upon the operator’s hands or upon the patient’s skin.

Solutions of gutta-percha in its different solvents, or of collodion in acetone, have been suggested as forming a covering for the hands by quickly drying upon the skin. The merit of these preparations is questionable, and the length of time required to dissolve the coating makes them impracticable. They have found little favor among surgeons.

Next to the sterilization of the parts to be operated, and the hands, may be considered _treatment of septic tissues or fluids_ and _protection against further infection_. Clean and uninfected tissues need no other precautions than those already described, _plus_ extra care in hemostasis, in order that there be no clot left in which germs may find a nidus, and the careful closure of the wound in such a way that no cavities or “_dead spaces_” may be left in which blood may later collect. Surgeons generally agree that the less clean tissues are handled and the less contact they undergo with foreign materials the more readily they heal. The ideal fluids with which to cleanse parts or to wash away blood clot are sterile salt solution and boiled water. Antiseptic solutions should not be used upon healthy tissue; but when abscess cavities have been opened and when pus or other infectious material have come in contact with fresh raw surfaces, every effort should be made to overcome its effects. It is customary in abdominal operations to “wall off” the site of a pus focus so that contamination of adjoining surfaces may be avoided, by placing gauze packing around it. Other expedients, _e. g._, the use of a rubber dam in any of its modifications, which will aid in this purpose, should be adopted. Upon brain surfaces, as upon the ruptured perineum, and in vaginal, rectal, and numerous other operations, a continuous fine stream of salt solution may be directed with great benefit.

An _abscess_ of any kind, no matter where located, should be _thoroughly cleansed_, its cavity disinfected, and easy access made to the outer wound. The interior of such cavities should be scraped with a sharp spoon. After curetting, a thorough washing or swabbing, often with the use of hydrogen dioxide, will often prove serviceable. Even a treatment of this kind does not afford as complete disinfection as may be secured by free application of pure carbolic acid or of a strong solution of zinc chloride (50 per cent.). The effect of this is not only to more completely sterilize, but to so sear the cauterized surfaces as to make them incapable of absorption. Excess of the caustic should be wiped away, or antidoted, in the case of carbolic acid by further swabbing with alcohol, or in the case of zinc chloride by merely washing out. Such a surface should heal naturally after sloughing, yet it is rarely safe to completely close such a cavity. A light packing of clean gauze, or, as the writer is fond of using it, of gauze sopped in balsam of Peru, will permit such a cavity to quickly close by the granulation process without further disturbance. Bone cavities, especially, are well treated with zinc chloride, it being difficult to so thoroughly disinfect such a focus that it may be safely closed without drainage; or they may be filled with bone chips or paraffin.

Visible tissue which is sure to slough should be removed with scissors or the sharp spoon, in order to save valuable time. Sometimes the actual cautery may be used to great advantage, as in chancroidal buboes, where every particle of raw surface will be infected by the pus which flows over it, and where it is advisable to cauterize not merely the suppurative focus, but everything which may come in contact with its pus.

=Instruments.=--Instruments are now all made of metal, usually nickel-plated, which will stand at least a certain amount of exposure to heat. It is not sufficient, however, to sterilize instruments alone, but basins, irrigator nozzles, and everything else which may be wanted during the course of an operation should be equally prepared for it. Inasmuch as hard rubber does not well stand even boiling water, instruments should be made, so far as possible, of metal or of glass. Boiling water, or “live” steam, are universally employed for this purpose; while to the water is often added 1 per cent. of ordinary washing soda, which enhances its serviceability. Fifteen to twenty minutes’ actual boiling, or its equivalent, will be sufficient for ordinary purposes. All instruments, such as knives and scissors, deteriorate after repeated use in this way and need to be frequently sharpened. Catheters also may be sterilized by boiling and should be constantly kept exposed to some volatile antiseptic, such as formalin (see above). Sterile material should be used upon the inhalers, and the metal parts of these, as well as mouth-gags, hypodermic syringes, and the like, should all be boiled.

=Dressings, etc.=--Not only the dressings which are to be employed after an operation, but the gauze, the cotton, or the sea-sponges which may be used during the same should have been twice sterilized either by dry heat or steam, in order to ensure security. No absorbent material should be packed tightly if it is to be subjected to steam, as it is not easily penetrated, even under pressure. Moreover, not only these materials but the sheets, gowns, aprons, towels, splints, and everything which may come into near approach or actual contact with the wound should be prepared in the same way. After sterilization all these materials should be enclosed in germ-proof, sterile wrappers of some kind or in sterile jars or boxes.

As a postoperative precaution, all materials which can be destroyed after use in a septic case should be _burned_. If this be not practicable, they should be soaked for twenty-four hours in a strong solution of corrosive sublimate, say 1 to 500. At the conclusion of operation there should be no opportunity left for dissemination of infection.

=Sponges.=--In place of sponges, gauze or absorbent cotton wrapped in gauze are now generally in use, prepared as above. There are some purposes for which sea-sponges are very convenient if they can be made reliable. Those which are received fresh from the dealer should be freed from sand by beating in a mortar, placed in a solution of 1 to 500 of potassium permanganate, and then transferred to a solution of sodium sulphite containing 5 per cent. by volume of pure hydrochloric acid; in this they remain until they are bleached out, which will take but a few minutes. They are then thoroughly washed in sterile water and stored in 5 per cent. carbolic solution.

=Suture Materials, etc.=--Wire, silkworm-gut, horse-hair, and silk or linen thread may be sterilized, if not rolled too tightly, by twice boiling for a half-hour, and then being allowed to dry, or preserved in 5 per cent. carbolic solution or in sterile alcohol. Disappointment often comes from rolling these materials so tightly upon spools that sterilization of the deeper layers is not complete. This is true of catgut as well as of the other animal sutures.

=Catgut.=--_Catgut_, so called, is usually made from the intestine of the sheep, and must be freed from anthrax germs or spores. It should be rolled loosely on spools or rods, each layer separated from that beneath by a piece of gauze. The writer prefers to free it from animal fat by a preliminary soaking in ether or benzene. After this it may be sterilized by boiling in alcohol, preferably absolute, which must be in a container not tightly closed. This is placed in water, raised gradually to boiling, and should boil for two hours. This process should be repeated at least once after the expiration of twenty-four hours. This is the simplest of all procedures and generally proves reliable. Other methods are those of exposure, for instance, to cumol, a volatile paraffin oil, in which it is boiled under pressure in a special apparatus, the temperature being raised considerably above the boiling point of water (300° F.). When the receptacle is opened the cumol is drawn off or evaporates and the catgut is left dry and sterile. It should be either kept dry in a sterile jar or in alcohol. Some prefer to add to the latter a small amount of oil of juniper, which has a little hardening effect upon the animal material.

Catgut should be tested repeatedly to be assured of its sterility. Special methods of preparing catgut are as follows:

=Formalin Gut= is prepared by placing the gut, wound as mentioned, in a 3 per cent. formalin solution for three hours. If the sterility of that which is used be not assured, then this preparation should be boiled in water for fifteen minutes. Catgut of large size should be immersed in a solution stronger than the above. It will probably be sufficient to give this a final boiling at the time of operation. This is almost as lasting as chromicized gut.

=Chromicized Gut.=--Gut to be thus prepared should be wound in single layers on spools and immersed in a solution of potassium bichromate 1.5 to 2.5, carbolic acid and glycerin each 10, and water 1000 parts. It is allowed to remain in this solution for twenty-four hours, then dried and boiled in water, or in alcohol under pressure, in which it is subsequently stored. According to the length of exposure and the strength of the solution, this gut will resist absorption from ten to thirty days.

=Iodine Gut= is growing in favor with some surgeons. It is prepared by immersing catgut in a 10 per cent. solution of iodine, in which it is kept for a week. After removal it is allowed to dry and is stored dry, but should be kept protected from exposure.

=Silkworm-gut= may be boiled in a 2 per cent. lysol solution for one hour, which makes it pliable. Sometimes it is convenient to have it stained black in order that the sutures may be better distinguished when removed. In this case it is allowed to stand in a 1 per cent. silver nitrate solution for from twelve to twenty-four hours. This gives it an almost black stain, but tends to make it more brittle. It may be kept in alcohol, or dry in a sterile receptacle.

=Silk.=--Silk should be spooled loosely, boiled in a similar solution for one-half hour, and again in plain water just before using. It may be stored dry or in alcohol. It may be also stained black.

=Celluloid Thread.=--This should be washed and scrubbed in green soap and hot water, after which it is spooled, and then boiled for thirty minutes. It may be stored dry or in alcohol. This is a linen thread covered with a film of celluloid.

=Kangaroo and Reindeer Tendons= are prepared essentially as is catgut, but if boiled in alcohol they must be kept covered with the fluid, as they tend to disintegrate.

=Drainage Tubes= of rubber should be boiled in soda solution for fifteen minutes, and may then be stored either in 1 per cent. formalin solution, or dry in a suitable tube.

=Oiled Silk and Rubber Tissues= are first prepared by washing in 1 to 500 sublimate solution, then dried, and exposed in an air-tight jar to the vapor of formalin or paraform.

The above are the methods usually in vogue in the writer’s clinic, and may be relied upon. These materials should be frequently tested by dropping fragments into culture tubes and watching the result, but only after taking the precaution to precipitate or neutralize the antiseptic previously used in their preparation.

=Antiseptic Solutions, Applications, etc.=--In well-regulated clinics sterile salt solution is always at hand. As has been stated the old six per mille solution may be improved by adding 1 part of potassium chloride and 2 parts calcium chloride. For emergency purposes tablets are now prepared which will permit the rapid preparation of these, of any desired strength. To this a little corrosive sublimate may be added without producing decomposition. When sublimate is used alone, or in other combinations, a little vegetable or mineral acid, such as tartaric or hydrochloric, should be added, as most of the water used contains lime.

When a maximum of bactericidal effect is desired with a minimum of irritation, the _silver salts_, either the lactate or the citrate, will probably afford the best results. The former may be used as strong as 1 to 300, the latter 1 to 500. The writer has frequently used these solutions for washing out the peritoneal cavity, in cases of tuberculous peritonitis, where they serve their purpose admirably. For washing out tuberculous joints and many other abscess cavities, solutions of silver nitrate of 1 to 1000 to 1 to 2000 are most serviceable; or, for the same purposes, boiled water, to which has been added sufficient tincture of iodine to give it a mahogany color. In caring for such cases it is good practice to alternate the solutions, using them on alternate days.

_Antiseptic powders or applications in dry form_ are useful for many purposes. At one time iodoform was very popular; it was supposed to act by virtue of the iodine set free in the presence of decomposing organic material. It is now seldom used, partly because of its tell-tale odor, and partly because of the disappointment which its use often brings. It is, moreover, an active toxic agent of itself, and has many times given rise to symptoms of intoxication, such as mental depression, delirium, nausea, and anorexia. Under all these circumstances free iodine can be detected in the urine.

There are numerous substitutes for iodoform, many of which are superior to it in antiseptic properties, while most of them are free from odor and toxic qualities. Two substances, however, are used extensively--_naphthalene_ and _bismuth subiodide_ or red iodide. The former has a marked odor and is more or less volatile, which makes it

## particularly valuable. The latter is odorless, non-toxic, and of much

greater value as an antiseptic than most of the others, because it will give off free iodine under favorable circumstances. A good plan is to use it in the preparation of gauze and dressings, as well as for a dusting powder upon the skin.

The absolute value of these local applications is questionable, because a wound will sometimes heal under the protection of a piece of foil or gutta-percha tissue as well as when dressed in any other way. This is true only of wounds in part surgically clean.

=Drainage.=--Drainage has been resorted to, more or less intermittently, since earliest historical times. It is provided for the _removal of deleterious fluids or of superfluous exudates or transudates_. _It is a recognition sometimes of a necessity, at other times a confession of fear_ which may or may not be justified. It is bad practice to cover a focus of previous gangrene or suppuration in such a way that the infected cavity is closed to the escape of accumulating fluid. This may be prevented by the use of a suitable drain. At times a clean operation may be made, and yet in such loose tissue, or to such an extent, that it is preferable to provide for the escape of blood rather than let it occur and force apart surfaces which should be in close contact. A drainage tube may serve as a vent through which blood may escape that has oozed after closure of the wound. After pelvic operations provision should be made for the withdrawal of accumulating fluid which might serve as a culture medium for germs. Drainage is therefore necessary in many instances.

It will suffice sometimes to suture loosely a part or the whole of a wound, so that should tension occur from retention there may be spontaneous escape. This may be termed _indirect drainage_, and sometimes has to be made still more complete by leaving out some sutures, or by placing _secondary sutures_, which are only utilized some days later, when previously infected surfaces have become healthy and are granulating, so that they can be brought together.

By _direct drainage_ secretions and fluids are guided toward the dressings, which should be absorbent or so arranged as to provide for their accommodation; thus in drainage of the gall-bladder or of the urinary bladder the tube may be connected with a suitable receptacle by siphonage. _Capillary drains may be_ made of a few strands of silkworm-gut, which is non-absorbable, or of catgut, which is absorbable, and to which, perhaps, no further attention need be paid. This will answer for conducting away small amounts of fluid which exude. Gauze, or its equivalent in the shape of some form of wicking, affords an excellent material for removing fluid by osmosis. The thinner the fluid the more perfectly it serves this purpose. The gauze must be changed frequently, as these lesions may become filled with coagulated material, in which case it would act merely as a plug. The so-called _cigarette drain_ consists of folds of gauze, or a small roll of it, surrounded by sterilized oiled silk or gutta-percha tissue, in which are cut numerous holes. The same purpose may be achieved, but often not so well, by a piece of rubber tubing split down one side. The gauze drains by osmosis, and the rubber prevents any adhesion to the wound margins and any pain in the removal of the drain; while a certain amount of fluid may escape around and outside the smoother surface.

When the fluids to be removed are more dense--_e. g._, pus--_tubular drains_ should be provided. These vary in size from that of a lead-pencil to that of the finger. A tube which is too small becomes easily plugged. They are perforated with numerous openings for the ready entrance of fluid save in those cases, like the gall-bladder or the pelvis, where it is desirable to drain only the depths of a cavity. These tubes are usually made of rubber, the purer forms of gum being preferable. For some purposes, especially in the pelvis, tubes of glass or aluminum are used; these are non-collapsible. They may be emptied by a capillary drain, or by the frequent use of a small syringe with a long nozzle, by which they are pumped out at regular intervals. Metal and glass tubes can be resterilized and used again. All other drainage material should be burned as soon as removed. There are occasions when it is well to use a _dressed drain_--_i. e._, a tube surrounded by absorbent gauze, and this again by rubber tissue or oiled silk. In many instances it is well to prevent the loss of a drainage tube by passing through its outer end a safety pin, or by stitching it to the margin of the skin wound. Tubes have been lost, especially within the thoracic cavity after operating for empyema, more often than is perhaps generally known, and for a lack of precaution in this respect.

Tubes of _decalcified chicken bone_ have been used and are occasionally serviceable. They are made by cleaning the cooked bones of the fowl, soaking them in 20 per cent. hydrochloric acid solution until decalcified, trimming the ends, cleaning the interior, and are then sterilized by boiling in a saturated solution of ammonium sulphate. They are then washed in sterile water and preserved in alcohol. They correspond to catgut, and will ordinarily last in the tissues for about eight days. They may be chromicized, as is catgut, in which case they endure considerably longer.

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