Finger Blocking Funnel During Catheter Insertion

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Hi, Stebrunner and Family of CIC Practitioners,                               October 4th, 2017

Several months ago Stebrunner announced his newly discovered method of Catheter Insertion by blocking the funnel throughout the insertion stage. I set up some experiments in my lab which seemed to indicate that it was air trapped in the catheter lumen expanding  as it warmed up to body temperature. The experiments were based on ColoPlast SpeediCath straight Hydrophilic catheters ranging from F-12 up to F-18. This explanation seemed too unlikely to be believable, yet it has proven to be the case many times since.

I adopted this technique myself and it worked beautifully at first but became progressively less effective as we moved into spring and summer. As the average room temperature rose from the winter 69F to the summer 76F the strategy began to fail. If my reasoning was sound, the closer the rising room temperature got to the body temperature, the less the thermal variation that would cause the air in the lumen to expand. So I took one of my 30 ml syringes, drew back the plunger to aspirate 5 ml of air and plugged the syringe into the catheter funnel. Then, as I gently pressed the catheter onto the inner (bladder) sphincter I depressed the syringe plunger. As soon as the air injected got to about 3 ml, in went the catheter, smoothly and painlessly just as it had always done in times past! Now, with the onset of winter I am back to the thumb-on-funnel routine.

I know, some will chastise me for injecting air into my bladder but, as long as the intent is to drain urine, most of the air in there will be expelled at the beginning of the stream moments later, providing patient remains standing or sitting. I am talking here of a relatively small amount of air (10 ml max.) spending a few seconds inside the urinary system. Greater quantities of air and longer time periods would call for an entirely different set of safety rules which are not relevant so are not mentioned here.

The first step before inserting anything into your bladder is to determine the current status of bladder, prostate, and urethra. Air based cystoscopies are becoming commonplace; mine was done over 70 years ago. However, complete expulsion of the air can take time, as in a day or two.  This can be a noisy process. My plea to all practicing urologists, radiologists, and other related specialists, is to please warn your patients of this so that they do not choose a public restroom or, if at home, not be in earshot of the family for the first few voids, or they may wind up with a delighted audience gleefully applauding the performance!

Another important point is that my background is in mechanical engineering rather than in medical field, so “buyer beware!”. Finally, I haven’t a clue why or how the lumen air pressure should have such a dramatic effect upon sphincter performance. Your opinions would be very welcome.

Warm regards to you all. Alan86734.

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  • Posted


    Your results seen to suggest that increasing the diameter of the catheter makes it easier to insert.

    Would going up to the next size eg 12-14Fr or 14-16 or 16-18 have the same result? I believe one of jimjanes posts touched on this topic

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    • Posted

      Hi jwrhn1951, you're correct on both. From the pure physics perspective, the larger the catheter size, the better the ease of catheter entry into the bladder by blocking the funnel. This said, catheter size must be dictated solely by whatever is the most comfortable for the patient. So, the smaller catheter sizes offer the least benefit from blocking the funnel; just not enough air in the catheter lumen. But, since this is exactly the same situation I describe for our summer operation, I suggest the syringe technique to add some air?.

      Your assumption that jimjames touched on this subject some time ago is also correct. Since Emis now show the complete thread (great idea!) you might find the reference to jimjames right here.

      jwrhn1951, thanks for your input; much appreciated.

      Warm regards. Alan

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  • Posted

    Hi JW,

    I appreciate your interest and experimentation, but I think there are easier and less invasive ways of accomplishing the same thing and I do not recommend this approach to anyone. 

    I am familiar with using a 30ml syringe with a catheter (for irrigation purposes) and it now only adds time to the process, but the process can potentially irritate the prostate and bladder due to the extra time involved and wiggling around. 

    Again, interesting stuff, but again there are other approaches to difficult catherizations such as trying different brand and type catheters, different sizes, different lubes, different techniques, relaxation exercises, etc. 


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    • Posted

      Hi Jim. Yes I agree with your views regarding CIC. However, I was trying to warn those who had undergone cystoscopies and procedures requiring the bladder to be distended using a fluid medium such as air. I should have been more explicit to differentiate this from Stebrunner's CIC interests and my goal of trying to find out exactly why blocking the funnel improved his CIC experience so much. 

      I am currently evaluating the Cure catheters. I started with two samples and results were promising so I ordered up my normal supply of 90. I immediately found change #1, if indeed this was intended. With the two samples I had no trouble popping the sachet of water just by squeezing it while it was still in the sterile packaging. With the large batch, however, I could not  get at the water this way. I ended up with some impressive hematomas (I am on blood thinners therapy), and even pliers failed. I had no alternative but to snip a corner off the foil sachet, as close as possible to the water line, insert the sachet back into the sterile wrapping, then squeeze it to burst it. This works quite well but having to have scissors handy is a bit of a pain.

      Now for the good stuff. Catheter passage through both sphincters is absolutely fantastic! I could barely feel the catheter. So, on with the evaluation. My opinion is that documentation is rather weak, particularly regarding instructions on how to use.

      In any event, thank you Jim for pointing this out. The more options we have, the better. Regards, alan86734.

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  • Posted

    Hi, Alan,

    Thanks for your efforts to figure out the mechanics of my technique! It continues to work for me, but I've had times when I've had some slight trouble with it, such as when I've come close to having a UTI and my urethra is irritated. Temps in my house usually run about 72F in winter to 76F in summer. I typically CIC with a Speedicath FR 12 coude or a Orego FR 14 coude, and it works with both.


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