US1168174A - Process for sterilizing and preserving surgical ligatures. - Google Patents

Description

CHARLES T. DAVIS, 01? BROOKLYN, NEW YORK.

EBOGESS FOR STERILIZING AND PRESERVING SURGICAL LIGATURES.

Helix-swing.

To all whom it may concern Be it known that 1, CHARLES T. DAvis, a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Processes for Sterilizing and Preserving Surgical Ligatures, of which the following is a specification.

This invention relates to an improved process for sterilizing and storing surgical ligatures and sutures, particularly those formed from animal tissue commonly known as catgut.

In the preparation tures for surgical use, of the utmost importance that they be absolutely sterile so as to avoid danger of infection. Several methods of preparing and storing the ligatures and sutures have heretofore been tried, one of those most largely used being as follows. The catgut, after having been prepared in the usual way, is inserted in a glass tube open atone end and then dried. The tube and its contents are then immersed in a suitable liquid, usually cumol, in a sterilizer and subjected to the necessary heat. The tubes containing the gut are now removed from the cumol and the surplus cumol rinsed 0E of the gut with chloroform.- After this, the tubes containing the sterile sutures are partially filled with chloroform, and the tubes are then sealed. Alcohol has also been largely used for this purpose. There are many objections to the use of these two latter substances, and there is also grave objection to the present method of sterilization because it renders possible, and in fact likely, the accidental contamination of the ligatures from the necessary handlings during the several-steps of manufacture.

It will be observed, therefore, that in the method heretofore employed, it has been necessary to use two different liquids, one, such as cumol, for sterilizing, having 'a high boiling point, and the other, such as alcohol or chloroform, for storing, being lighter and more volatile.

It is the object of the resent invention to provide a single liqui capable of performing both functions, and, moreover, being free from the many objections formerly experienced with substances employed in the old processes."

Attempts to use cumol of ligatures and suas a storing fluid Specification of Letters Patent.

it is, as is well known,

Patented J an. 111, 1916.

Application filed May 17, 1915. Serial No. 28,599.

have failed. This substance, which is one of the higher coal tar derivatives or substitution products of the benzene ring, has a boiling point so high that it will not readily evaporate from the ligature when the same is removed from the tube. Also, it has been found that the cumol which clings to the ligature proves exceedingly irritating to the wound, and its use as a tubing or storing fluid is impossible.

Chloroform has been found unsuitable as a storing fluid for many reasons, chief among which are the following: First- Chloroform breaks down under comparatively moderate heat into chlorin and hydrochloric acid, both of which exert an extremely harmful effect upon the ligatures. Second-Under the influence of sunlight, free-chlorin, hydrocloric acid and carbonyl chlorid (phosgene) are liberated, the latter product in particular being extremely ob jectionable. ThirdThe disagreeably irritating and harmful efiect of chloroform upon the tissues. Fourth-The inadequately low boiling point of chloroform, which prevents the successful application of the temperature necessary for the sterilization of the tubes after being sealed. Fifth-The susceptibility of chloroform to deterioration from age. SixthChloroform can hold water in solution, which is very harmful to the ligatures, particularly to that kind of ligature most widely used, namely, catgut, for as is well known, the slightest degree of moisture tends to convert'the collagen in the catgut into gelatin, with the result that when the catgut is subjected to thermal sterilization it becomes brittle, weakened, and twisted.

' Alcohol is objectionable for many reasons, chief among which are its low boiling point, its inefficacy asa solvent of the fatty matter of the ligature, and for the further reason that, as is well known, alcohol has a strong affinity for Water, and hence it is impossible under workable conditions to secure alcohol which is perfectly free from water. above stated, the presence of even a minute quantity of water in the storing liquid tends to convert the collagen of the gut into gelatin, with'the result that when the gut is sub 1 jected to any adequate sterilizing temperawhich would satisfactorily meetthe requirements of a successful combined sterilizing and, storing or tubing liquid. As a result of such research, I have found that the lower methyl substitution products of the benzene ring are eminently suitable for such use. Particularly, I have found that the mono-methyl substitution product known as toluol or toluene answers every requirement. Also, the di-methyl substitution products known as ortho-, meta-,and paraxylene have been found satisfactory, as Well as mixtures of these various substances. Mixtures of any or all of these compounds with benzol itself may also be employed.

The primary characteristics of these substances are that they are entirelynon-irritating to the tissues of the body and, while evaporating readily, have a boiling point sufficiently high for sterilization purposes.

Moreover, they do not break down or deteriorate under the influence of heat, light,

or age, do not contain or mix with water,

and will not even hold water in suspension.

Still other valuable properties of this benzene series of hydrocarbons are their anti septic or germicidal. virtues, their superior I heat conducting qualities, their softening and clarifying effect upon the ligatures, their chemical stability, and their low cost in comparison with chloroform or alcohol. In addition, the products named are powerful solvents for oils and fats, and are therefore of great value in removing the fats and fatty acids occurring in catgut ligatures, and which are irritating to the tissues of the bddy. As above stated, these substances have the characteristic of being highly volatile, which insures that when the tube is broken for use by the surgeon, the substance quickly evaporates; but if itshould happen that the ligature s applied so quickly as to prevent perfectevaporation, the substance will not have any deleterious effect whatever upon the wound, but will simply have a shght'cooling effect, due to the evaporation.

These substances leave no residue upon evaporation, so that any possibility of irritation of the wound from foreign bodies, (a foreign-body irritation as it is known among surgeons), is completely avoided.

As a result of my invention, sterilization can be very effectively carried on after the tubes or containers are sealed, while by the ing positive the assurance of sterility, and

coincidentally effecting a great economy in the amount of time and skilled e-flort otherwise required when conducting the processes of sterilization and the handling of the ligatures under aseptic conditions and amid sterile environments, as is necessary when employing the more elaborate but less positive method heretofore in vogue, (z'. e., the sterilization of the ligatures before the sealing of the tubes and the subsequent filling of the tubes with their contents of sterile storing fluid).

Benzol itself boils at 80.5 (1, toluol at 111, and the xylenes boil at from 137 to 143 C. These substitution products of the benzene ring are for the most part obtainable by fractional distillation of coal tar, and all of them go over below or at 143 C. If distillation is carried beyond this point, the tri-methyl derivatives, such as cumol and mesitylene, are obtained, which are of such an oily nature and are so irritating to the tissues as to be unsuitable as a storing fluid. That portion of the distillate approximating the constitution of the monomethyl derivative toluene, and having a boiling point between 110 and 120 C. has been found to give particularly satisfactory results. Recently, other methods of producing toluol and its homologues have been discovered. 1

With the improved storingfluid above described, the method of putting up the ligatures is extremely simple. A ligature having been first prepared in. the usual wayis placed in a tube, and, while one end of the tube remains open, is subjected to the necessary drying process. The tube is then partially filled with my improved storingfluid and sealed. The sealed tube and its contents are then subjected to a suitable sterilizing heat.

The temperature employed for steriliza- -tion varies with the nature of the particular liquid used, but is always substantially above the boiling point of such liquid, and in no case less than 100 C. For example, in using toluol, which boils at 232 F. (111 0.), a temperature of about 240 to 250 F. would be employed, while with benzol, the temperature would not run so high. In each instance, the temperature is raised to such a point'as will produce a pressure within the tube sufficient to force the vapor well into the pores of the ligature, and thoroughly impregnate the same. No liquid more volatile than benzol can practically be employed, since it has about as low a boiling point as will permit the application of a sufficiently high temperature to effect sterilization without unduly raising the internal pressure in the tube.

\Vhat I claim is:

1. The process of preserving surgical ligatures and the like which comprises storing them in contact with a hydrocarbon having a boiling point between 80 and 143 C.

2. The process of preserving surgical ligatures and the like which comprises storing them in contact with a coal-tar distillate going over between 80 and 143 C.

3. The process of preserving surgical ligatures and the like which comprises storing them in contact with a coal-tar distillate of the benzene series, having a boiling point at or below 143 C.

4:. The process of preserving surgical ligatures and the like which comprises storing them in contact with a hydrocarbon of the benzene series having a boiling point at or below 143 C.

5. The process of preserving surgical ligatures and the like which comprises storing them in contact with an organic compound containing only hydrogen and carbon and having a boiling point at or below 143 C.

6. The process of preserving surgical ligatures and the like which comprises storing them in contact with the lower methyl substitution products of the benzene ring.

'7. The process of preserving surgical ligatures and the like which comprises treating them with the methyl substitution prodnets of the benzene ring below the trimethyl products.

8. The process of preserving surgical ligatures and the like which comprises treating them with methyl substitution'products of the benzene ring having a boiling point at or below l i3 C.

9. The process ligatures and the like which comprises treating them with mono-methyl or di-methyl substitution products of the benzene ring, or mixtures thereof.

10. The process of preserving surgical ligatures and the like which comprises treating them with toluene.

In testimony whereof I have aiiixed my signature.

CHARLES T. DAVIS.

of preserving surgical