US 3297029 A
Description (OCR text may contain errors)
Jan. 10, 1967 g, BRlNKMAN ETAL 3,297,029
INHALATOR DEVICE Filed March 13, 1964 2 Sheets-Sheet 1 INVENTORS. DAVID C. BRINKMAN and BY MICHAEL M. ROBBINS 1 v D. c. BRINKMAN ETAL. 3,
INHALATOR DEVICE Filed March 15; 1964 2 Sheets-Sheet z INVENTORS. 39 DAVID C. BRINKMAN and BY MICHAEL M. ROBBINS United States Patent 3,297,029 INHALATOR DEVTCE David C. Brinkman and Michael M. Robbins, lindianapolis, Ind, assignors to The Dow Chemical Company, Midland, Mich, a corporation of Delaware Filed Mar. 13, 1964, Ser. No, 351,675 2 Claims. (Cl. 128-l8h) The invention relates to a device for administering a volatile, normally liquid, inhalation anesthetic to small animals such as dogs and cats.
In the use of an anesthetic, such as methoxyfluorane, in the veterinary medical field, it is desirable to have apparatus which is easy to use, reliable, portable, easily maintained, and of low initial cost and upkeep.
The principal objectives of the invention are to provide all or substantially all of these attributes in a single assembly of parts.
The objects and advantages of the invention will be better understood on becoming familiar with the following description and the appended drawings in which:
FIG. 1 is a front elevation of the apparatus of the invention, and
FIG. 2 is an end view of the body member of the apparatus of FIG. 1, with the finger cot, funnel and suction cup removed, and
FIG. 3 is a view similar to FIG. 2 showing the shape of the projecting body portion before flattening, and
FIG. 4 is a sectional view of the body member only, taken along line 4-4 of FIG. 2, and
FIG. 5 is a view similar to FIG. 4, being a sectional view of the body member only, but showing air passages of different proportions, and
FIGS. 6, 7 and 8 are perspective views showing insertable plug members which may be used to reduce the volume of the air passage in the body member, and
FIG. 9 is a View of an exploded assembly of a fibrous pad holding means.
In the drawings like reference numerals indicate like parts.
Referring more particularly to the drawings, the complete assembled inhalator device, as shown in FIG. 1, consists of an integral body member, indicated generally bylthe numeral 10, having a relatively larger cylindrical central portion 11 and first and second smaller projecting portions 12, 13 extending axially from the cylindrical central portion, or at least generally parallel to the axis of the cylindrical central portion.
The first smaller projecting portion 12, is adapted to be readily received by the open end of flexible tubing, e.g., gum rubber tubing'used to connect the inhalator device to a nose cone or an endotracheal tube. The first smaller projecting portion 12 is generally cylindrical in shape, and may be tapered to make a good fit with the flexible tubing, or, if desired, may be provided with circumferential ridges 14, as shown.
The end 15 of the second smaller projecting portion 13, which is remote from the cylindrical central portion 11, is closed by a non-rebreathing valve 16, in the form of a gum rubber finger cot having a slit 17 cut in the generally longitudinal direction of the finger cot by a sharp-edged instrument about 4 inch or more from the end 15 of the smaller projecting portion 13. Slit 17 is in the form of an incision made through a side of the finger cot without substantially any removal of material from the finger cot. Other types of non-rebreathing valves may be used if desired, e.g., a ball check valve having a low density ball with a specific gravity well below 0.2, or a so-called flapper valve; however, these have generally been found to be either more expensive, or, position sensitive.
The funnel 18 serves as an imperforate walled holder for a fibrous pad 19, as of cotton, and as an inlet for inspired air. The fibrous pad 19 may be wetted with anesthetic in any suitable manner as well understood in the art. The fibrous pad 19 may be soaked or dipped in anesthetic and placed in the funnel 18, or, in the more usual procedure, the anesthetic is poured onto the pad periodically in sufiicient quantity to wet substantially all the fibers, but never enough to hood the pad so that liquid anesthetic drips therefrom.
The inhalator device may be provided With any suitable base, e.g., a heavy base attached to the body member 19, or the device may be clamped on the operating table near the animal. However, a very convenient base is provided in the form of a rubber suction cup 24) which is attached to the cylindrical central portion 11 as by threadable attachment.
The integral body member 10 is conveniently made of polyethylene, though other polymeric materials which are resistant to the solvent action of anesthetic materials may be used. The integral body member 10 may also be made of metal, if desired. Polyethylene funnels are conveniently available on the market in suitable sizes and proportions, though funnels formed of other plastic or resinous material or of metal may be used.
The details of construction of the integral body member 10 will be more readily understood with reference to FIGS. 2, 3 and 4. FIG. 2 is an end view of integral body member 10, with the finger cot 16 removed, exposing the end 15 of the second smaller projecting portion 13. Also exposed to view is the air passage 21 Which extends entirely through the cylindrical central portion 11 and the first smaller projecting portion 12 and communicates with the enlarged passage 22 in the second smaller projecting portion 13. The enlarged passage 22 is larger merely because of the practical reason of makin the second smaller projecting portion 13 thin walled enough so that it can be flattened into elliptical form. A highly important aspect of the reliability of the operation of the finger cot 16 as a non-rebreathing valve lies in the partial flattening of the end 15 of the second smaller projecting portion 13. The finger cot collapses and exhibits valve-like action much more readily when attached to an elliptical part than when attached to a circular part. Sometimes it appears to be conducive to good valve action to align the slit or slits 17 in the finger cot 16, shown in FIG. 1, with either apex 23 of the flattened projecting portion 13 shown in FIG. 2.
Shown in dotted outline in FIG. 2 is the radially directed inlet 24 in the cylindrical central portion 11. The inlet 24 is provided with a counterbored section 25 having suitable dimensions to receive a fibrous pad holder, e.g., the funnel 118 shown in FIG. 1. Also shown in dotted outline is a hole 26 drilled into the lower side of cylindrical central portion 11 of suitable dimensions to receive the threadable attaching element from the base, e.g., suction cup 20 shown in FIG. 1. The hole may be tapped if desired, but it has been found unnecessary if the hole is undersized and the body member is made of polyethylene.
The end view of FIG. 3 shows the appearance of the integral body member 16 just after the part has been turned on a lathe and before the end 15 of the smaller projecting portion 13 has been flattened by being mechanically squeezed to the flattened state.
One of the problems encountered in anesthetizing animals is to provide the least amount of dead air space within the inhalator equipment without increasing respiratory efiort. If the passageways are too constricted the animal does not inspire nor expel air freely enough and the resulting forced shallow respiration may cause death from anoxia. If the passageways are too expansive, the tidal volume of a small animal under deep anesthesia and breathing very shallowly may not be sufficient to cause expulsion of expired air from the apparatus or, on inspiration, be of insufficient volume to overcome the excessive dead air space. It is, therefore, desirable to have means for varying the internal dead air space in the inhalator, preferably simply and inexpensively.
Accordingly, in FIG. 5 is shown a part of another embodiment of the invention in which the air passages are differently proportioned, and provision is made for adapting this form of the device for animals of differing body weights. This is perhaps most easily accomplished by providing apparatus with a relatively large internal dead air space suitable for larger animals, and employing appropriate means for reducing the dead air space when using the device on smaller animals.
The cylindrical central portion 11 has been modified by providing an enlarged zone 27 in the air passage 21. The radially directed inlet 24 is not countered in this embodiment but is of uniform bore to let the funnel 18 of FIG. I extend down part way into zone 2'7.
The volumes of zone 27 and space 22 are conveniently reduced by inserting therein a suitable plug member formed of any appropriate anesthetic-resistant material, e.g., resistant plastic, or metal. A suitable cylindrical plug member indicated generally by reference numeral 28 is shown in FIG. 6. The plug member 28 is inserted, small end 29 first. The flared end 30 is designed for easier grasping for removal. An air passage 31 extends longitudinally of the plug member and communicates with intersecting air passage 32 which extends from the flat surfaced notch 33 to air passage 31. Various such plugs may be employed with different size animals with varying sizes of air passage 31, as needed. Notch 33 is adapted to receive the end of a funnel, e.g., funnel 18 of FIG. 1. The funnel, desirably, bears against the flat surface, prevents the plug member 2 8 from rotating, and keeps air passage 32 in communication with the funnel.
Any suitable plug member will do which appropriately reduces internal volume of the integral body member and which does not cut off communication between air passage 21 and the inlet passage 24- and the outlet passage 22. Other types of designs of plug members which may be used are plug member 34 of FIG. 7 and lug member 35 of FIG. 8.
In yet another embodiment of the invention provision is made for conserving the anesthetic and for varying the anesthetic to air ratio drawn in on inspiration. The apparatus for this modification is shown in FIG. 9 and consists of a funnel 18 having a slot or opening 36 in the side wall of the shank 37 of the funnel; and a rotatable sleeve 38 adapted to slidably rotate on the shank 37 of the funnel l8 and having, likewise, a slot or opening 39 which may be aligned with opening 36 to bypass inspired air completely or partially around the portion of the funnel holding the fibrous pad 19. Alternatively, if it is desired to bypass no air, the sleeve is rotated so as to completely cover opening 36.
To avoid the possibility that the fibrous pad 19 may get wedged or packed down into the shank 37 of the funnel 18, a small perforated retaining plate 40 may be placed in the funnel 18 just above the shank 37. And to prevent the loss of the fibrous pad 19 on accidental inversion or jarring of the inhalator device during use, a perforated cover plate 41 may be placed over the funnel 18. Preferably the cover plate 41 is provided with a flanged edge which fits the rim 42 of the funnel 118 closely so as to grip the rim. It will be understood that the perforations in both of plates 4-0 and 41 must be large and/or numerous enough so as not to seriously impede air flow therethrough.
In making the integral body member of the device of the present invention, it is preferable to start with cylindrical bar stock about 1.5 to 1.75 inches in diameter. As indicated above, the stock may be of metal or of anesthetic-resistant polymeric material, more preferably polyethylene. The tube connection side is turned down to an appropriate size and ridged if desired. The non-rebreathing valve connecting portion is turned down to suitable dimensions. If a finger cot valve is to be used, the valve connecting portion is turned down to about one inch external diameter, and internally bored so as to leave a wall thickness of about l s inch. The axially aligned passage through both the cylindrical central portion and the other smaller projecting portion or tube connection can then be bored out, as Well as the intersecting radially directed inlet air passage which is counterbored to receive the funnel shank in tight fitting relationship. The end of the valve connecting portion is then flattened to an oval or elliptical shape. In the event polyethylene is used as material of construction, the end of the valve connecting portion is compressed or squeezed completely flat. Upon being released, the flattened end very slowly relaxes to a permanently set oval shape.
It is apparent that other manufacturing techniques can be applied in producing the apparatus of the invention, particularly for quantity production. Thus, for example, the cylindrical central portion and the two smaller projecting portions including their respective openings and air passages may be produced as a unit by casting of metal or resin or by injection molding of a suitable thermoplastic material. Alternatively, the smaller projecting portions may be separately prepared from extruded tube stock and then be assembled with a preformed cylindrical central portion by pressfitting, cementing or other suitable joining method. Final assembly with valve means and fibrous pad holding means can then be carried out as previously described.
The apparatus of the invention having been thus fully described, obvious modifications thereof will at once be obvious to those skilled in the art, and therefore the scope of the invention is to be considered limited only by the scope of the appended claims.
We claim: 1. A device for the administration of an inhalation anesthetic which comprises:
an integral body member having a relatively larger cylindrical central portion and first and second smaller projecting portions, said first smaller projecting portion having a generally cylindrical form and being adapted to be readily received by an open end of patient connecting means, said second smaller projecting portion being generally cylindrical in form and having first and second ends, said first end being joined to said larger cylindrical central portion and said second end being partially flattened so as to be elliptical in section and having a non-rebreathing valve operatively appended thereto, and said cylindrical central portion and said first and second smaller projecting portions being substantially aligned along substantially parallel axes; means defining an air passage through each of said cylindrical central portion and said first and second smaller projecting portions, each said air passage being disposed approximately parallel to the axis of each said portion, and said air passage being so interconnected that air may pass sequentially through said first smaller projecting portion, said cylindrical central portion and said second small-er projecting portion and vice versa;
said non-rebreathing valve being a generally cylindrical finger cot formed of elastomeric material having a closed end and an open end, the open end being attached to said second end of the second smaller projecting portion, said finger cot having at least one slit formed without substantially any removal of material from said finger cot and said slit being formed longitudinally of the finger cot; means defining an approximately radially disposed inlet air passage in the cylindrical central portion extending through and from a surface of the cylindrical central portion to the air passage axially disposed therein and communicating therewith; imperforate walled fibrous pad holding means having an inlet and outlet, said outlet being operatively attached to said cylindrical central portion so as to provide direct communication between said outlet and the said means defining an approximately radially disposed inlet air passage; and a fibrous pad substantially wetted by inhalation anesthetic and disposed Within said holding means. 2. The device as in claim 1 in which the slit in the said finger cot is approximately aligned with either apex of the elliptical shaped flattened end of said second smaller projecting portion.
References Cited by the Examiner UNITED STATES PATENTS 2,317,237 4/ 1943 Wilen. 2,499,734 3/1950 Edmondson et al. 128l97 2,960,985 11/1960 Wiese 128l88 3,028,873 4/1962 Kindred 128-188 X FOREIGN PATENTS 604,558 7/1948 Great Britain.
RICHARD A. GAUDET, Primary Examiner.
W. E. KAMM, Assistant Examiner.