PREVENTING URINARY CATHETER BLOCKAGES
According to the users' information leaflet, Nitrofurantoin is used 1) to cure urinary infections and 2) to prevent them. It is proved below that if used to prevent urinary infections, in my case it also prevented catheter blockages. I do not know for how many other people with catheter blockages it would be effective. It would be unlikely to work for those who have blockages caused by kidney stones or bladder stones.
The normal dose for preventing urinary infections is 50 or 100mg daily at night. Having taken 50mg per day for 30 days, this was reduced to 50mg 3 or 4 times per week and then to just nights when I was feeling feverish as might warn of a urinary infection or when there was a considerable amount of sediment in my catheter. That worked for me, but others might need different doses. Like other medications, Nitrofurantoin comes with many cautions and possible side-effects, listed in the users' information leaflet, but I have not had any.
As well as taking Nitrofurantoin I also repositioned my catheter by pulling it forward immediately after going to bed to prevent the intake being obstructed by pressing up against my bladder wall.
I have also used several supporting methods to keep my catheter clear. These are listed below.
WHAT CAUSED THE BLOCKAGES?
From January to July 2016 the misery of my spinal injury was aggravated by the torment of catheter blockages. Here are a few observations to help identify what had been causing them:
1 My suprapubic catheter was installed in May 2013, about 4 months after my spinal injury. I had no blockage during the first two years and eight months but I had 23 between 17/1/16 and 24/7/16. Towards the end of that period, they became more frequent.
2 All the blockages occurred soon after changing positions from sitting upright in my wheelchair to lying flat on my back in bed. On every occasion I have wakened up sweating and trembling with exceptionally violent spasms, usually between midnight and 1am. There is a highly significant relationship between time and occurrence of blockages. If we use simple dichotomy that blockages could occur at either day or night, if there were no relationship between time of blockage and occurrence, the probability of any one blockage occurring at night would be 0.5. The probability of all 23 blockages occurring at night would be 0.5 to the power 23 = 0.000000119 or a little over 1 chance in ten million. The methods of calculation possible and the interpretation of the results are similar to those used in the trials on pp 3-5.
3 The nurse has never taken more than a few minutes to unblock the obstruction. It takes about 10 minutes for the sweating and spasms to subside enough to be clearly noticeable and a further 10 minutes for the sweating to have gone and the spasms returned to their normal level. In perhaps 8 or 10 of my 23 cases of blockage, it was uncertain why the blockage had cleared. Sometimes there was insufficient sediment for that to be a likely cause. Movement of the catheter in some cases seemed to be sufficient to make the urine to flow. Unblocking the catheter did not in every case cause a sudden, clearly visible flow of urine.
4 Only once has a blockage recurred during the same night. On this occasion, two nurses arrived at 10.50pm and replaced my catheter which was choked with 'sludge'. At 2.40am I woke sweating again. The same nurses returned. This time the blockage was 'positional'.
5 There were at least two causes of the blockages - bacterial and physical obstruction.
6 For about half of the blockages, the nurse mentioned sediment and/or 'pus' as the likely cause. On some occasions, including the most recent, only 36 hours after a bladder wash-out, the nurse said there was no sediment.
7 My leg bag is supposed to be changed weekly. On 3 or 4 occasions, the nurse has mentioned a dirty leg bag, when the carers (and me) had forgotten about it or when we had run out of them.
8 On the morning following several of the blockages I have had a bout of sweating which has always been stopped by taking Nitrofurantoin. This seems to indicate that I had a urinary infection, and that the infection was caused by bacteria which also caused the blockage the night before. A urine sample has never been taken at the time of a blockage or soon after. However, it seems likely that the bacteria killed by Nitrofurantoin created the sediment which resulted in most of the blockages.
I do not have a good explanation as to why I had no blockages between installation of my catheter in May 2013 and 17/1/16 despite having more than a dozen urinary infections during this period. I can only state the obvious that whatever bacteria were causing these infections did not produce sufficient sediment to cause a blockage but there was a change in January 2016. Before July 2016 I took Nitro