URINARY CATHETER BLOCKAGES:

NOT SOMETHING WE CAN LIVE WITH

Part 1 of 2

BARRY SIMPSON

I had 23 catheter blockages between January and July 2016. Then I found a way of stopping them. I have had none since. This has left me with the impression that blockages have been too readily accepted as a normal part of having a catheter. They are an additional misery for people who, in many cases, have other serious conditions; they are more dangerous than is widely recognised and waste a great deal of nursing time unblocking catheters which do not need to be blocked.

Here is the method which stopped my urinary infections and catheter blockages immediately, completely and without any noticeable side-effects. I do not know for how many others it would be suitable.

It's coming up to 1'o clock in the morning. I waken up sweating profusely. I'm getting tremendous shocks of spasms. I have an overwhelming urge to move my legs but I can't. I can't move: following a spinal injury in 2013, I have been paralysed from the shoulders down. I fumble round the bed to find the 'phone. Eventually I find it, despite very little movement or sensation in my hands, now clawed up like an animal's paws. With my knuckles and a protruding little finger, I 'phone for a nurse, desperately trying to hold the 'phone to my ear. Fortunately a kind and thoughtful nurse had previously given me their direct number so that I don't have to endure the 111 service. The spasms and sweating are becoming even more severe. By the time she arrives, which can be over two hours later, the bedsheets are wet with sweat. 'Sorry I took so long. I've had a lot of catheter blockages tonight'.

Another one: between the nights of 16/17th January and 23/24th July 2016 I had 23 like that, typically between about midnight and 1am - long enough for urine to build up if my catheter had actually become blocked immediately after going to bed.

BLOCKAGES: CAUSES AND REMEDIES - NITROFURANTOIN AND CATHETER REPOSITIONING

I had a suprapubic catheter installed in May 2013. I had no blockage for the first two years and eight months.

At least two-thirds, but not all of my blockages were accompanied by sediment in my catheter. The last two blockages both occurred on the night of 23/24th July 2016. My catheter was replaced after the first of these. The second blockage was described by the nurse as 'positional'. Attending an earlier blockage, a different nurse had suggested that a possible cause was the catheter intake pressing against my bladder wall. So there seemed to be at least two causes of the blockages: by sediment and by the position of the catheter.

Why were all my blockages shortly after changing positions from sitting in my wheelchair to lying flat in bed? That is a better question than is my answer to it. The positional blockages were likely to have been caused by my catheter coming up against my bladder wall or the intake becoming too low for drainage of urine by gravity. The sedimentary blockages might have resulted from the catheter moving to a lower part of my bladder where sediment had collected.

Late on the morning of 24th July I began sweating heavily and my spasms became more severe. I took these to be signs of a urinary infection: I took 50mg Nitrofurantoin and it was soon cleared. This was not the first time that symptoms of an infection followed a blockage. It appeared that the bacteria causing the infections were also creating the sediment which caused most of the blockages. So using Nitrofurantoin to prevent infections (rather than to cure them) in my case, also prevented catheter blockages. From the evening of 24th July I started taking 50mg Nitrofurantoin each day at about 8pm. I have had no blockage since.

In these circumstances, I try to maintain an awareness of the symptoms of septicaemia, the infection, and sepsis, the body's inflammatory reaction to it and to be aware that urinary infections can develop into septicaemia and sepsis:

http://www.healthline.com/health/septicemia#overview1http://www.nhs.uk/Conditions/Blood-poisoning/Pages/Introduction.aspxand because I have a spinal injury, also autonomic dysreflexia:

http://www.webmd.com/hypertension-high-blood-pressure/tc/spinal-cord-injury-autonomic-dysreflexia-topic-overview******************************************************************

SUMMARY OF METHODS TO PREVENT CATHETER BLOCKAGES

May 2013 to 15th January 2016: no blockage; Nitrofurantoin taken occasionally to cure urinary infections.

16/17th January 2016 to 23/24th July 2016: 23 blockages; Nitrofurantoin taken occasionally to cure urinary infections.

Since March 2016: weekly bladder wash-outs.

Since 24th July 2016: no blockage;

50mg Nitrofurantoin taken on these evenings to prevent infections and blockages:

July 24-31;

August 1-22, 24, 25, 26, 28, 29, 30;

September 1, 2, 4, 7, 8, 10, 13, 16, 18, 19, 22, 25;

October 1, 5, 6, 7, 11, 14, 15, 17, 20(100mg), 21, 22, 23, 25, 29, 31;

November 4, 5, 7, 10, 13, 16, 19, 22, 24, 26, 28;

December 1, 3, 5, 8, 11, 12, 17, 22, 31;

January 8, 16, 18, 22;

February 5, 13, 16, 20, 25;

March 11, 25;

April 2, 8, 13, 22, 28;

May 1, 12, 19;

June 3, 13, 18;

July 2, 10, 23,

Catheter repositioning to prevent non-sedimentary blockages.

Since January 2017: rolling catheter between hands and consumption of natural antibiotics: lemon tea, vinegar on food.

*******************************************************************

What about the blockages not caused by sediment - the 'positional' blockages? To prevent these I simply gently pull my catheter forward each night immediately after going to bed to pull it away from my bladder wall. At the same time I also unstrap the catheter and leg bag from my leg and lay it flat on the bed to help gravity by ensuring that as much of my catheter as possible is at a lower level than the intake.

The Users' Information Leaflet says that the normal dose of Nitrofurantoin for preventing infections is 50mg or 100mg daily at night but does not say for how long. On the principle that it is best not to take more medication than necessary, after 30 days taking 50mg, I began tentatively to omit it on a few nights and risk the horror of a blockage. For about 3 months I took 50mg on 3-4 nights per week and then reduced it further to only nights when I had a considerable amount of sediment in my catheter or sweating which could warn of a urinary infection.

SUPPORTING METHODS TO PREVENT CATHETER BLOCKAGES

The district nurses started giving me weekly bladder wash-outs soon after my blockages started: so the first few nights I omitted Nitrofurantoin were wash-out days. Wash-outs probably reduced the number of blockages but did not eliminate them. Not long after I reduced Nitrofurantoin to less than every night, I did begin to get sediment in my catheter. This seems to have been kept in amounts insufficient to cause a blockage by carers rolling the catheter between their hands to disturb it and by consuming natural antibiotics, including adding vinegar to food and drinking lemon tea (not surprising - the bladder wash-out solution contains citric acid). To make lemon tea, I simply cut an unpeeled lemon in half, cut up the half into pieces or slices put in a cup and add hot water, topping up several times and squeezing the lemon with a spoon. Lemons can be used in many other ways too:

http://www.healthextremist.com/lemon-peel-benefits-why-you-shouldnt-throw-out-that-lemon-peel/I will never know whether rolling my catheter and taking natural antibiotics would have been sufficient to stop the blockages without Nitrofurantoin. I started them in January 2017, six months after my blockages had been stopped. However, it does appear that they have allowed a reduction in the dose.

COULD THE BLOCKAGES HAVE STOPPED BY SOMETHING ELSE OR BY CHANCE?

Could something else have stopped my blockages immediately, completely and for such a long time? All I can say is that I am not aware of doing anything else on and following 24th July that could be expected to stop blockages other than taking Nitrofurantoin and catheter repositioning.

Although I have had no blockage since the night of 23/24th July 2016, often I have sediment in my catheter. When this looks sufficiently severe to risk a blockage, I take 50mg Nitrofurantoin about 8pm. Within an hour or two, the sediment is reduced or has gone completely.

I had 23 blockages in a period of 190 days from 16th January to 24th July 2016, no blockage since (365 days up to 24th July 2017). The probability of Nitrofurantoin and catheter repositioning having had no effect can be calculated as the probability of 23 random occurrences in a period of 190+365 days all being in the first 190 days.

The probability of any one of them being in the first 190 days is 190/(190+365) = 0.3423;

considering any two of the blockages, the probability of both of them being in the first 190 days would be 0.3423 x 0.3423 and so on until .....

the probability of all 23 being in the first 190 days is 0.3423 multiplied by itself 22 times = 1.95595e-11 = 0.0000000000195595 which is a little less than 2 chances in a hundred thousand million (a hundred thousand million is the number that 0.0000000000195595 would have to be multiplied by to get 1.95595).

http://www.rapidtables.com/calc/math/Exponent_Calculator.htmThe base is 0.3423 and the exponent is 23.

So the probability that Nitrofurantoin and catheter positioning were not associated with stopping blockages is 0.0000000000195595; therefore the probability that they have been associated with stopping blockages is 1 - 0.0000000000195595 = 0.9999999999804405 where absolute certainty equals 1.

The binomial distribution can also be used with the same result:

http://www.vassarstats.net/textbook/ch5apx.htmlwhere N = 23, k = 23, p = 0.3423 and the answer is p(k out of N)

The multinomial distribution can be used too:

https://www.easycalculation.com/statistics/multinomial-distribution.phpwhere the number of outcomes is 2 (blockage on a day in first 190 days /blockage a day in following 365 days), the number of occurrences 23 and 0, p = 0.3423 and 1-0.3423 = 0.6577.

These calculations are based on cautious assumptions. The probability of there being no association between taking Nitrofurantoin and the absence of blockages is likely to be even smaller than the very small probability of 1.95595e-11. On about 10 of the 190-day period with blockages I took Nitrofurantoin to cure urinary infections. I had no blockage on these days. So there is a case for reducing the period to 180 days, or fewer if the effect of Nitrofurantoin lasted for more than one day, and adding 10 or more days to the blockage-free period. If the period were reduced to 180 days, the probability of all 23 blockages being in the first 180 days would become (180/(180+375)) to the power 23 = 5.6465e-12.

There is no practical difference between using a period of 190 days, 180 days or fewer. In all cases the probability of all 23 blockages being in this period by chance is so small as to be negligible. This very small probability means that it is practically certain that Nitrofurantoin and catheter repositioning were associated with stopping my blockages; it is not the probability of having a blockage tonight; nor is it a prediction of when a blockage can be expected.

PREDICTING FUTURE BLOCKAGES

Prediction methods rely on making inferences from the past: so while the treatment is never followed by a blockage, the prediction will remain zero for any period into the future.

However, where treatment sometimes fails, any of several methods can be used to estimate when future failures will occur.

If I were to have a blockage, the negative binomial distribution, also known as the Pascal distribution, could be used to predict the probability of a further blockage on each of the days following.

http://stattrek.com/online-calculator/negative-binomial.aspxThe number of trials is the number of days after the first blockage, the number of successes is the number of blockages to be predicted (1 if the next blockage is to be predicted, 2 if it is to be the blockage after that and so on), probability of success on a single trial would be 1 divided by the number of days between the start of my blockage-free period and the first blockage and the negative binomial probability is the probability of the chosen blockage (1st, 2nd or whatever was chosen) occurring on the chosen number of days after the first blockage.

A cumulative version, which can make some calculations less laborious, is available at:

http://calculator.vhex.net/post/calculator-result/negative-binomial-discrete-cumulative-distributionThe geometric distribution is a particular case of the negative binomial distribution where the number of successes, in my case, blockages, is equal to 1: so if the timing of only the next blockage is to be estimated, it can be used instead of the negative binomial distribution.

http://www.calcul.com/show/calculator/geometric-distribution?max=7&k=6&p=0.5Here, the number of successes is the number of days without a blockage before the next one occurs, the probability of success is as for the negative binomial distribution and the maximum number of trials is the number of days for which you require the probability to be calculated. This calculator can save time by using the probability mass function, which shows the probabilities of a blockage on the days leading up to the day chosen.

It is possible to predict the number of blockages within any specified period using the Poisson probability distribution:

http://stattrek.com/online-calculator/poisson.aspx.

For example, suppose we wish to predict the chance of 1 blockage in a period of 7 days, the Poisson random variable would be 1. The average rate of success is the average number of blockages which in the past have occurred in 7 days (number of blockages/number of days in observation period x 7). To predict the chance of 2 blockages in 28 days, the Poisson random variable would be 2 and the average rate of success would be the average number of blockages in 28 days. As long as there are no blockages on nights following taking Nitrofurantoin, the average number of blockages for any period is 0: so until there is a blockage, the prediction of future blockages for any period is zero.

The negative binomial distribution, the geometric distribution and the Poisson probability distribution rely on the events (blockages in this case) being independent - not connected to each other, even indirectly by a common cause - and randomly distributed. This is liable to introduce inaccuracies into the predictions if the connections are not taken into account. On the other hand, if predictions from these techniques do not fit observations, that will be evidence that there are connections between the events (blockages) and that there is likely to be a common cause.

It might seem inconsistent that the effectiveness of Nitrofurantoin and catheter repositioning was demonstrated by the lack of randomness in the distribution of the 23 blockages between the 190 days without the treatment and the 365 days with it, while the techniques for predicting future blockages rely on them being randomly distributed. Not necessarily so; the predictive techniques would be used only in the period when the treatment is taking place.

...... continued as part 2