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A Self-inflating Bag Catheter
THE JOURNAL OF UROLOGY
Vol. 88, No. 5 November 1962 Copyright © 1962 by The Williams & Wilkins Co.
Printed in U.S.A.
A SELF-INFLATING BAG CATHETER FREDERIC E. B. FOLEY From the Urological Department, Ancker Hospital, Saint Paul, Minn.
During the quarter century since the bag catheter was made commercially available by American Anode Incorporated at request and under instruction of the writer, no change has been made in its fundamental structure and operation. Innumerable different "models" of the device directed to special purposes have appeared. Many of these have been of value and have served good purposes, but in all of them the original fundamental structure and operation of the catheter have remained unchanged except for the Gilbert self-sealing plug of the inflating duct. This was a useful contribution and made use of the catheter much more convenient. It is not usual that a surgical device in widespread use for such a long period, produced in millions each year and enthusiastically accepted by the profession, should remain in its original form without change in its fundamental structure or operation over a period of more than 25 years. This has not been the ca.se with most surgical devices so useful and extensively used as the inflatable bag catheter. This fact was thought-provoking. In recent years changes surrounding the catheter have been directed to convenience of the user and saving the labor of hospital personnel. These modifications have accomplished a great deal in those directions. Sterile packaging of the catheter has eliminated completely time and labor of hospital personnel formerly spent in autoclaving or boiling and wrapping catheters. Irradiation and gas sterilization have greatly facilitated sterile packaging of the catheter. The value placed on the convenience and saving of labor by hospital personnel labor made by these contributions is clearly indicated by the fact that presently most bag catheters are supplied in sterile packages by manufacturers, and are ready for immediate use. Despite those improvements, use of the catheter has continued to require time and labor of Accepted for publication April 5, 1962. Presented before the Twin City Urologic Society, October 27, 1961 meeting. 724
hospital personnel in sterilizing the paraphernalia required for its use: syringe for bag inflation, water for inflation medium and the container for it. These appear to be very small items, but preparing them for use and bringing them to the place of catheterization impose inconvenience and use of costly time. The latter is partially avoided by use of a sterile, packaged disposable syringe and sterile water contained in a purchased vial. But the task of assemblying all the paraphernalia is not avoided. This may be very troublesome if any of the items are found not on hand when needed. Avoiding these requirements of the ordinary sterile water-inflated bag catheter should be of great benefit to the physician obliged at night to install a selfretaining bag catheter at a patient's home. The aforementioned impediments to clinical use of the catheter pointed to room for improvement in the original form and operation of the catheter in the direction of eliminating the inflating paraphernalia: sterile syringe, needle or adapter for the syringe, water for inflation, container for the water, lubricating jelly and sterile covered tray. It appeared this would be accomplished by a self-inflating or automatically inflated bag catheter. The final form of self-inflating catheter here presented accomplishes this object. In production, these changes can be made at trifling cost largely offset by the cost of providing the sterilized items required for water inflation of the standard form bag catheter. The first attempt to provide a self-inflating catheter (fig. 1) was beset by unforeseen objectionable features, technical difficulties for production, and prohibitive properties of latex rubber. A 1 ½ inch long steel pin of small diameter, with tapered smooth tip and enlarged diameter head, was introduced through the large inside diameter of the diverging segment of the inflating duct. The tip of the pin was pushed ¼ inch into the small diameter inflating duct of the catheter shaft. This securely plugged the inflating duct at that point. With the occluding
SELF-INFLATING BAG CATHETER
steel plug in place, a standard Gilbert selfsealing plug was cemented in the open end of the inflation duct. With needle and syringe 20 cc air was injected into the thick walled diverging distention duct. Under a pressure of about 40 pounds per square inch the compressed air occupied the space between the occluding steel pin and the Gilbert self-sealing plug. Force of the compressed air caused elongation and distention of the inflating duct and in some cases a localized sausage-shaped, balloon-like dilata-
B
.c
Fm. 1. Preliminary form of self-inflating bag catheter. Small diameter steel pin with tapered tip and larger diameter head, A, was introduced through large inside diameter of proximal portion of inflating duct. Tip of pin was forced short distance into small-diameter inflating duct of catheter shaft which it securely occluded, as shown in B. Open end of inflating duct was closed with Gilbert self-sealing plug. With hypodermic needle and syringe, 15 cc air was forcibly injected into inflating duct. Compressed to reduced volume under elevated pressure, air was contained in segment of duct between occluding pin and self-sealing plug, C. To inflate catheter bag, small-diameter inflating duct was unplugged by withdrawing tip of pin within it back into largediameter proximal segment of duct thus permitting compressed air to pass to and inflate catheter bag.
725
tion of the thick walled diverging inflation duct ~2 inch in diameter and about an inch long. With the head of the steel pin within the inflating duct in the grasp of the thumb and forefinger, the tapered end of the pin was withdrawn from the small diameter inflating duct of the catheter shaft which was thus unplugged permitting the compressed air under pressure to pass to the thin walled bag of the catheter and inflate it to proper size. At first the device appeared to be an adequate self-inflating catheter. However, within 24 hours much of the air had permeated through the thin walled catheter bag and left it deflated to a size inadequate for self-retention of the catheter. Carbon dioxide permeated through the bag wall even more rapidly than air and nitrogen permeated through the bag at about the same rate as air. Water instead of air for inflation was tried. While it did not permeate through the catheter bag, it had other undesirable features. Water being not compressible like air, the volume of water required for bag inflation always produced an undesirable sausage-shaped dilatation of the distention duct even larger than the balloon-like dilatation sometimes caused by the needed quantity of air. Elongation of the rubber forming the ballooned up segment was in excess of 300 per cent. Rubber chemists believed that the rubber under pressure and elongation present would deteriorate rapidly and have a comparatively short useful shelf life. This appeared to preclude clinical usefulness of the device. A second attempt to provide a self-inflating bag catheter was somewhat of a compromise and make-shift (fig. 2). A thick walled latex balloon or bulb of 1 inch inside diameter and 8.6 cc capacity was filled with water and connected to the Gilbert self-sealing plug of an F16 5 cc bag catheter by means of a 19 gauge hypodermic needle. With the bag segment of the catheter
Fm. 2. Second preliminary form of self-inflating bag catheter. Thick walled latex bulb, A, is attached to catheter via self-sealing plug of catheter-distention duct and hypodermic needle integral with discharge nipple of bulb. Catheter bag is inflated by squeezing water-filled bulb. Bulb and its needle are pulled away from catheter and discarded, and catheter remains installed in bladder. Device left much to be desired.
726
FREDERIC E. B. FOLEY
passed to a position well within the bladder, the water-filled bulb was compressed in the grasp of the thumb and forefinger displacing the bulb contained water into the catheter bag. The needle and its attached bulb were disconnected from the catheter leaving it self-retained in the bladder. While this second form of "self-inflating" bag catheter appeared to be practical it was not truly self-inflating, and the comparatively large water-filled bulb attached to the catheter was clumsy and awkward. Inflation of the bag by compressing the bulb was troublesome and the device left much to be desired. The afore described forms of self-inflating bag catheter were not satisfactory for clinical use and were not capable of large scale production except at prohibitive cost. These features were avoided in a truly self-inflating bag catheter which leaves nothing to be desired (fig. 3). In this case it was proposed to use a Freon (Dupont) in liquid phase as the inflating substance with the liquid contained in a small rupturable glass ampoule placed in the large inside diameter of the proximal segment of the inflating duct with open end of the inflating duct closed with a Gilbert self-sealing plug. On experimental inflation of catheter bags with the commonly used refrigerants Freon 12 and Freon 22 it was disappointing that both permeated through the latex catheter bag even more rapidly than carbon dioxide. On the other hand, Freon C318, developed by the Dupont
Company for use as a propellant for Aerosol food containers, was found not to permeate through the bag when it was wet with urine or water. It was found that only eight one hundredths of a cubic centimeter of Freon C318 in liquid phase yielded a volume of vapor sufficient to inflate the bag to proper size. This very small volume of Freon C318 in liquid phase could be contained in a glass ampoule of truly minute size. With the foregoing facts at hand it was undertaken to make glass ampoules containing the required volume of liquid Freon C318. This was no easy problem as this substance has a boiling point of 21F, a freezing point of minus 40F and a vapor pressure of 28 pounds per square inch at room temperature. Howe1·er, home-made ampoules of the required sort 1Yere produced -~finally with reasonable rapidity and in substantial numbers. The final form of self-inflating bag catheter here described (fig. 3) eliminates the last remaining inconvenience and labor requirement of hospital personnel involved in use of the catheter. These advantages can be provided at trifling cost, almost completely offset by cost of the previously required inflating paraphernalia. The catheter as supplied may be contained in a gas sterilized package with accompanying small packet of lubricating jelly. Thus the catheter becomes self-inflating and completely selfsufficient with nothing but itself required for its clinical use. The device eliminates entirely
Fm. 3. Final form of self-inflating bag catheter. Inflating duct, .11, is integral with drainage lumen body of catheter and unlike conventional catheter, does not diverge from it. Proximal end of distention duct is closed with conventional self-sealing plug. Within proximal end of distention duct, A, is glass ampoule, B, containing inflating Rubstance in liquid form. At midpoint of its length ampoule is scored which permits it to break cleanly into two parts when forcibly bent in grasp of thumbs and forefingers of the two hands, C. Upon rupture of ampoule, released inflating substance of precisely measuretl quantity immediately vaporizes ,,-ithin sealed inflation duct and inflates bag, D, to proper size.
SELF-INFLATING BAG CATHETER
the troublesome features of the steel-pin-plugged distention duct, the clumsy sausage-shaped balloon-like distention of the proximal end diverging inflating duct, or the water-filled bulb, and makes no demands on the latex rubber beyond its capabilities occasioned by high pressure and excessive elongation. Within the proximal end segment of the bag distention duct is placed an ampoule containing Freon C318 inflating substance. When the bag segment of the catheter has been passed to a position well within the bladder, the bag is inflated by breaking the ampoule at its middle.
727
This is accomplished by bending the ampoule contained in the distention duct in the grasp of the thumbs and forefingers of the two hands. The accurately measured quantity of inflating substance released from the broken ampoule immediately vaporizes and inflates the bag to proper size. Size and position of the vapor-filled bag within the bladder are readily shown in cystograms. Clinical experience has disclosed that in certain cases of female patients, the vapor-inflated bag causes less irritation and patient discomfort than the conventional water-filled bag. The reason
FIG. 4. Cystograms showing positions of vapor-inflated bag in relation to vesical neck. Woman aged 64, Ancker Hospital Register No. 212888. Right hydronephrosis. Right nephrectomy 1 week prior to cystogram. Self-inflating bag catheter was installed and 100 cc contrast medium instilled into bladder. A, with patient standing erect, traction was made on catheter emerging from urethra. Vapor-inflated bag lies in snug contact with vesical neck and bladder floor and has drawn them down into abnormally low position. B, traction on catheter was released, followed by patient's walking about for several minutes. Inflated bag has risen up out of contact with vesical neck.
FIG. 5. Cystograms showing positions of vapor-inflated bag in relation to vesical neck. Woman aged 82, Ancker Hospital Register No. 236977. Bilateral cataracts. Operation for cataract 2 weeks prior to cystogram. Postoperative complete retention of urine, persisting partial retention of urine (90 cc residual). Atony of bladder. Self-infiating bag catheter was installed and 100 cc contrast medium instilled into bladder. A, with patient standing, erect gentle traction was made on catheter emerging from urethra. Vaporinflated bag is in snug contact with vesical neck and has drawn it down into abnormally low position. B, traction on catheter was discontinued and its proximal end was lifted up and supported by taping it to abdomen leaving downward loop of minimal length of emerging catheter. followed by patient's walking about for several minutes. Buoyant vapor-inflated bag has risen away from vesical neck and is not in contact with it. C, catheter emerging from urethra was moved in and out a number of times, and was left gently drawn down following which patient walked about for several minutes. Buoyant filled bag has floated upward considerable distance away from vesical neck with which it is no longer in contact.
728
FREDERIC E. B. FOLEY
for this is not obvious. Possibly it is due to buoyancy of the vapor-inflated bag causing it to float upward out of contact with the sensitive vesical neck and trigone. If extensive clinical use of the self-inflating catheter confirms this interpretation, buoyancy of the vapor-inflated bag may prove to be a most desirable feature of the self-inflating catheter. (See figs. 4 and 5.) Deflation of the bag to permit removal of the catheter is accomplished by inserting a hypodermic needle into the distention duct through its plugged end or by cutting with scissors across the proximal end of the catheter and distention duct immediately beyond the plug. The latter will permit removal of the expended inflating ampoule and re-use of the catheter without the self-inflating feature. Usual practice nowadays is to use an inflatable bag catheter only once and not resterilize it for re-use. This is a necessity as to the self-inflating feature of the catheter for in clinical use it is not practical to replace the expended inflating ampoule with a new operative ampoule.
If the self-inflating catheter with Freon-containing ampoule has not already been gas sterilized in a "sterile package," it must not be sterilized by heat--not autoclaved, not boiled. To do so might cause rupture of the inflating ampoule. The catheter may be sterilized by immersion in a solution such as 1 to 1000 zephiran or 1 to 1000 mercury oxycyanide. Or it may be gas-sterilized if gas-sterilization equipment is available. It must not be sterilized by irradiation. To do so would have a deleterious effect on the inflating substance and render it toxic. In case of bag rupture, the toxic substance would be released in the bladder. The not-irradiated inflating substance Freon C318 (Dupont) is completely non-toxic and non-irritating. It has been approved by the Food and Drug Administration for use as a food additive. Manufacture of the self-inflating bag catheter shown in figure 3 jg contemplated by United Medical Products, Hopkins, Minn.
841 Saint Clair Ave., Saint Paul, Minn.
Vol. 88, No. 5 November 1962 Copyright © 1962 by The Williams & Wilkins Co.
Printed in U.S.A.
A SELF-INFLATING BAG CATHETER FREDERIC E. B. FOLEY From the Urological Department, Ancker Hospital, Saint Paul, Minn.
During the quarter century since the bag catheter was made commercially available by American Anode Incorporated at request and under instruction of the writer, no change has been made in its fundamental structure and operation. Innumerable different "models" of the device directed to special purposes have appeared. Many of these have been of value and have served good purposes, but in all of them the original fundamental structure and operation of the catheter have remained unchanged except for the Gilbert self-sealing plug of the inflating duct. This was a useful contribution and made use of the catheter much more convenient. It is not usual that a surgical device in widespread use for such a long period, produced in millions each year and enthusiastically accepted by the profession, should remain in its original form without change in its fundamental structure or operation over a period of more than 25 years. This has not been the ca.se with most surgical devices so useful and extensively used as the inflatable bag catheter. This fact was thought-provoking. In recent years changes surrounding the catheter have been directed to convenience of the user and saving the labor of hospital personnel. These modifications have accomplished a great deal in those directions. Sterile packaging of the catheter has eliminated completely time and labor of hospital personnel formerly spent in autoclaving or boiling and wrapping catheters. Irradiation and gas sterilization have greatly facilitated sterile packaging of the catheter. The value placed on the convenience and saving of labor by hospital personnel labor made by these contributions is clearly indicated by the fact that presently most bag catheters are supplied in sterile packages by manufacturers, and are ready for immediate use. Despite those improvements, use of the catheter has continued to require time and labor of Accepted for publication April 5, 1962. Presented before the Twin City Urologic Society, October 27, 1961 meeting. 724
hospital personnel in sterilizing the paraphernalia required for its use: syringe for bag inflation, water for inflation medium and the container for it. These appear to be very small items, but preparing them for use and bringing them to the place of catheterization impose inconvenience and use of costly time. The latter is partially avoided by use of a sterile, packaged disposable syringe and sterile water contained in a purchased vial. But the task of assemblying all the paraphernalia is not avoided. This may be very troublesome if any of the items are found not on hand when needed. Avoiding these requirements of the ordinary sterile water-inflated bag catheter should be of great benefit to the physician obliged at night to install a selfretaining bag catheter at a patient's home. The aforementioned impediments to clinical use of the catheter pointed to room for improvement in the original form and operation of the catheter in the direction of eliminating the inflating paraphernalia: sterile syringe, needle or adapter for the syringe, water for inflation, container for the water, lubricating jelly and sterile covered tray. It appeared this would be accomplished by a self-inflating or automatically inflated bag catheter. The final form of self-inflating catheter here presented accomplishes this object. In production, these changes can be made at trifling cost largely offset by the cost of providing the sterilized items required for water inflation of the standard form bag catheter. The first attempt to provide a self-inflating catheter (fig. 1) was beset by unforeseen objectionable features, technical difficulties for production, and prohibitive properties of latex rubber. A 1 ½ inch long steel pin of small diameter, with tapered smooth tip and enlarged diameter head, was introduced through the large inside diameter of the diverging segment of the inflating duct. The tip of the pin was pushed ¼ inch into the small diameter inflating duct of the catheter shaft. This securely plugged the inflating duct at that point. With the occluding
SELF-INFLATING BAG CATHETER
steel plug in place, a standard Gilbert selfsealing plug was cemented in the open end of the inflation duct. With needle and syringe 20 cc air was injected into the thick walled diverging distention duct. Under a pressure of about 40 pounds per square inch the compressed air occupied the space between the occluding steel pin and the Gilbert self-sealing plug. Force of the compressed air caused elongation and distention of the inflating duct and in some cases a localized sausage-shaped, balloon-like dilata-
B
.c
Fm. 1. Preliminary form of self-inflating bag catheter. Small diameter steel pin with tapered tip and larger diameter head, A, was introduced through large inside diameter of proximal portion of inflating duct. Tip of pin was forced short distance into small-diameter inflating duct of catheter shaft which it securely occluded, as shown in B. Open end of inflating duct was closed with Gilbert self-sealing plug. With hypodermic needle and syringe, 15 cc air was forcibly injected into inflating duct. Compressed to reduced volume under elevated pressure, air was contained in segment of duct between occluding pin and self-sealing plug, C. To inflate catheter bag, small-diameter inflating duct was unplugged by withdrawing tip of pin within it back into largediameter proximal segment of duct thus permitting compressed air to pass to and inflate catheter bag.
725
tion of the thick walled diverging inflation duct ~2 inch in diameter and about an inch long. With the head of the steel pin within the inflating duct in the grasp of the thumb and forefinger, the tapered end of the pin was withdrawn from the small diameter inflating duct of the catheter shaft which was thus unplugged permitting the compressed air under pressure to pass to the thin walled bag of the catheter and inflate it to proper size. At first the device appeared to be an adequate self-inflating catheter. However, within 24 hours much of the air had permeated through the thin walled catheter bag and left it deflated to a size inadequate for self-retention of the catheter. Carbon dioxide permeated through the bag wall even more rapidly than air and nitrogen permeated through the bag at about the same rate as air. Water instead of air for inflation was tried. While it did not permeate through the catheter bag, it had other undesirable features. Water being not compressible like air, the volume of water required for bag inflation always produced an undesirable sausage-shaped dilatation of the distention duct even larger than the balloon-like dilatation sometimes caused by the needed quantity of air. Elongation of the rubber forming the ballooned up segment was in excess of 300 per cent. Rubber chemists believed that the rubber under pressure and elongation present would deteriorate rapidly and have a comparatively short useful shelf life. This appeared to preclude clinical usefulness of the device. A second attempt to provide a self-inflating bag catheter was somewhat of a compromise and make-shift (fig. 2). A thick walled latex balloon or bulb of 1 inch inside diameter and 8.6 cc capacity was filled with water and connected to the Gilbert self-sealing plug of an F16 5 cc bag catheter by means of a 19 gauge hypodermic needle. With the bag segment of the catheter
Fm. 2. Second preliminary form of self-inflating bag catheter. Thick walled latex bulb, A, is attached to catheter via self-sealing plug of catheter-distention duct and hypodermic needle integral with discharge nipple of bulb. Catheter bag is inflated by squeezing water-filled bulb. Bulb and its needle are pulled away from catheter and discarded, and catheter remains installed in bladder. Device left much to be desired.
726
FREDERIC E. B. FOLEY
passed to a position well within the bladder, the water-filled bulb was compressed in the grasp of the thumb and forefinger displacing the bulb contained water into the catheter bag. The needle and its attached bulb were disconnected from the catheter leaving it self-retained in the bladder. While this second form of "self-inflating" bag catheter appeared to be practical it was not truly self-inflating, and the comparatively large water-filled bulb attached to the catheter was clumsy and awkward. Inflation of the bag by compressing the bulb was troublesome and the device left much to be desired. The afore described forms of self-inflating bag catheter were not satisfactory for clinical use and were not capable of large scale production except at prohibitive cost. These features were avoided in a truly self-inflating bag catheter which leaves nothing to be desired (fig. 3). In this case it was proposed to use a Freon (Dupont) in liquid phase as the inflating substance with the liquid contained in a small rupturable glass ampoule placed in the large inside diameter of the proximal segment of the inflating duct with open end of the inflating duct closed with a Gilbert self-sealing plug. On experimental inflation of catheter bags with the commonly used refrigerants Freon 12 and Freon 22 it was disappointing that both permeated through the latex catheter bag even more rapidly than carbon dioxide. On the other hand, Freon C318, developed by the Dupont
Company for use as a propellant for Aerosol food containers, was found not to permeate through the bag when it was wet with urine or water. It was found that only eight one hundredths of a cubic centimeter of Freon C318 in liquid phase yielded a volume of vapor sufficient to inflate the bag to proper size. This very small volume of Freon C318 in liquid phase could be contained in a glass ampoule of truly minute size. With the foregoing facts at hand it was undertaken to make glass ampoules containing the required volume of liquid Freon C318. This was no easy problem as this substance has a boiling point of 21F, a freezing point of minus 40F and a vapor pressure of 28 pounds per square inch at room temperature. Howe1·er, home-made ampoules of the required sort 1Yere produced -~finally with reasonable rapidity and in substantial numbers. The final form of self-inflating bag catheter here described (fig. 3) eliminates the last remaining inconvenience and labor requirement of hospital personnel involved in use of the catheter. These advantages can be provided at trifling cost, almost completely offset by cost of the previously required inflating paraphernalia. The catheter as supplied may be contained in a gas sterilized package with accompanying small packet of lubricating jelly. Thus the catheter becomes self-inflating and completely selfsufficient with nothing but itself required for its clinical use. The device eliminates entirely
Fm. 3. Final form of self-inflating bag catheter. Inflating duct, .11, is integral with drainage lumen body of catheter and unlike conventional catheter, does not diverge from it. Proximal end of distention duct is closed with conventional self-sealing plug. Within proximal end of distention duct, A, is glass ampoule, B, containing inflating Rubstance in liquid form. At midpoint of its length ampoule is scored which permits it to break cleanly into two parts when forcibly bent in grasp of thumbs and forefingers of the two hands, C. Upon rupture of ampoule, released inflating substance of precisely measuretl quantity immediately vaporizes ,,-ithin sealed inflation duct and inflates bag, D, to proper size.
SELF-INFLATING BAG CATHETER
the troublesome features of the steel-pin-plugged distention duct, the clumsy sausage-shaped balloon-like distention of the proximal end diverging inflating duct, or the water-filled bulb, and makes no demands on the latex rubber beyond its capabilities occasioned by high pressure and excessive elongation. Within the proximal end segment of the bag distention duct is placed an ampoule containing Freon C318 inflating substance. When the bag segment of the catheter has been passed to a position well within the bladder, the bag is inflated by breaking the ampoule at its middle.
727
This is accomplished by bending the ampoule contained in the distention duct in the grasp of the thumbs and forefingers of the two hands. The accurately measured quantity of inflating substance released from the broken ampoule immediately vaporizes and inflates the bag to proper size. Size and position of the vapor-filled bag within the bladder are readily shown in cystograms. Clinical experience has disclosed that in certain cases of female patients, the vapor-inflated bag causes less irritation and patient discomfort than the conventional water-filled bag. The reason
FIG. 4. Cystograms showing positions of vapor-inflated bag in relation to vesical neck. Woman aged 64, Ancker Hospital Register No. 212888. Right hydronephrosis. Right nephrectomy 1 week prior to cystogram. Self-inflating bag catheter was installed and 100 cc contrast medium instilled into bladder. A, with patient standing erect, traction was made on catheter emerging from urethra. Vapor-inflated bag lies in snug contact with vesical neck and bladder floor and has drawn them down into abnormally low position. B, traction on catheter was released, followed by patient's walking about for several minutes. Inflated bag has risen up out of contact with vesical neck.
FIG. 5. Cystograms showing positions of vapor-inflated bag in relation to vesical neck. Woman aged 82, Ancker Hospital Register No. 236977. Bilateral cataracts. Operation for cataract 2 weeks prior to cystogram. Postoperative complete retention of urine, persisting partial retention of urine (90 cc residual). Atony of bladder. Self-infiating bag catheter was installed and 100 cc contrast medium instilled into bladder. A, with patient standing, erect gentle traction was made on catheter emerging from urethra. Vaporinflated bag is in snug contact with vesical neck and has drawn it down into abnormally low position. B, traction on catheter was discontinued and its proximal end was lifted up and supported by taping it to abdomen leaving downward loop of minimal length of emerging catheter. followed by patient's walking about for several minutes. Buoyant vapor-inflated bag has risen away from vesical neck and is not in contact with it. C, catheter emerging from urethra was moved in and out a number of times, and was left gently drawn down following which patient walked about for several minutes. Buoyant filled bag has floated upward considerable distance away from vesical neck with which it is no longer in contact.
728
FREDERIC E. B. FOLEY
for this is not obvious. Possibly it is due to buoyancy of the vapor-inflated bag causing it to float upward out of contact with the sensitive vesical neck and trigone. If extensive clinical use of the self-inflating catheter confirms this interpretation, buoyancy of the vapor-inflated bag may prove to be a most desirable feature of the self-inflating catheter. (See figs. 4 and 5.) Deflation of the bag to permit removal of the catheter is accomplished by inserting a hypodermic needle into the distention duct through its plugged end or by cutting with scissors across the proximal end of the catheter and distention duct immediately beyond the plug. The latter will permit removal of the expended inflating ampoule and re-use of the catheter without the self-inflating feature. Usual practice nowadays is to use an inflatable bag catheter only once and not resterilize it for re-use. This is a necessity as to the self-inflating feature of the catheter for in clinical use it is not practical to replace the expended inflating ampoule with a new operative ampoule.
If the self-inflating catheter with Freon-containing ampoule has not already been gas sterilized in a "sterile package," it must not be sterilized by heat--not autoclaved, not boiled. To do so might cause rupture of the inflating ampoule. The catheter may be sterilized by immersion in a solution such as 1 to 1000 zephiran or 1 to 1000 mercury oxycyanide. Or it may be gas-sterilized if gas-sterilization equipment is available. It must not be sterilized by irradiation. To do so would have a deleterious effect on the inflating substance and render it toxic. In case of bag rupture, the toxic substance would be released in the bladder. The not-irradiated inflating substance Freon C318 (Dupont) is completely non-toxic and non-irritating. It has been approved by the Food and Drug Administration for use as a food additive. Manufacture of the self-inflating bag catheter shown in figure 3 jg contemplated by United Medical Products, Hopkins, Minn.
841 Saint Clair Ave., Saint Paul, Minn.