Simple, Inexpensive Device to Measure Maximum Flowrate

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I posted the following in another thread, but thought I should create a new thread so that those who are interested might benefit.  Many researchers and urologists consider the maximum urination flowrate (QMax) to be an important measure of the amount of bladder outlet obstruction (BOO).  Usually this flowrate is measured in a urologist's office, but can also be "roughly" measured using a cheap device you can purchase on Amazon.  This allows you to get a quantitative idea of the max flowrate in the comfort of your own home.  You can measure it as often as you like.  Here's what I posted in the other thread:

So I received the $11 urine flowmeter that I purchased from Amazon (MDTI Uflow meter).  Their website contains information on how the unit works.  The unit has a funnel on top and three narrow chambers below it ultimately ending in an orifice.  When urine flows through the device it backs up into one of the chambers because the orifice constricts  the outflow.  While urinating, the urine level in one of the chambers will at some point remain  steady for some amount of time (depends on how much is urinated).  The instructions say that when the urine level is constant (steady), the person should note which chamber that occurs in.  If the level is constant in the lowest chamber (closest to the orifice) the peak flow rate is less than 10 ml/sec.  In the middle chamber the peak flow rate is between 10 and 15 ml/sec. In the top chamber the peak flow rate is greater than 15 ml/sec.  The instructions say to lean forward while you are urinating in  order to see where the level is in the device.  I've found it is easier to lean a bit to the side and look at the urine  level from the side. The instructions say that "if most of your measurements are in the top of the tube (> 15ml/sec), your urine flow is acceptable.  If most of your measurements are in the bottom or middle of the tube, you should seek advice from your doctor/nurse".

While this is a coarse instrument, it does give you a rough estimate of the peak flow rate.  Many urologists and researchers believe that measuring the  peak  flow rate is a proxy for the level of constriction  in the urinary tract.  This makes sense to me.

While the chambers do seem to only provide an approximate value, it seems to me that if the level is in the middle chamber (10 to 15 ml/sec), then where that levei is in that chamber might allow for interpolations.  For example, if the steady level of urine  is  halfway up the middle chamber, then the peak flow rate is probably halfway between 10 and 15 ml/sec.  This interpolation probably cannot be made in the top chamber (> 15 ml/sec). For the bottom chamber one would have to assume that a level right at the orifice results in a flow of 0 ml/sec in order to interpolate.  

At any rate it is a cheap, easy-to-use instrument for home use.  It might be useful for watching worsening or easing of  LUTS symptoms. 

 

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  • Posted

    Thanks for the info. And while I think the more info/data points the better, I don't think flow rate is as important as many uro's make it out to be. It may be a marker of BOO but it may not be. I have a slow flow rate but am able to empty my bladder completely. A relative of mine also has a low flow rate and is also able to empty his bladder completely and he doesn't even have a bph diagnosis. So again, flow rate is a good data point, but I wouldn't get hung up on it as other data points are more important such as PVR. No one ever got hydronephrosis or a distended bladder from low flow but they have from too high a PVR.

    Jim

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  • Posted

    So why can't I just use a graduated beaker and time how long it takes me void a given amount IE: I pee 300 ml in 30 seconds means I am flowing about 10 ml/sec

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    • Posted

      That method gives you the average flowrate. Studies typically measure the maximum flowrate to assess severity of BOO.  If you plot instantaneous flowrate versus time, it basically has the shape of a hill.  The maximum flowrate is the apex of the hill.  If you have flowrate measured at your uro's office, I'd be very surprised if it wasn't Qmax that they report (although they might also report the average flowrate).

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    • Posted

      Also, if you had BPH surgery performed, where study results indicate what the improvement in the maximum flowrate would be after surgery, and you are now using the average flowrate to measure your own results, you could be way off.  In your example of 300 ml in  30 seconds, I would bet that the maximum flowrate was over 15 ml/sec (and probably higher).
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    • Posted

      When I needed to know PVR, doing the beaker thing worked fine for me; now, because I know my AVERAGE rate of flow, I just count seconds in my head, and yes, I usually empty 300ml in 30 seconds.  Easy math.  The $11 gizmo measures MAXIMUM flow rate, which our simple approach cannot give.  But that info mattes only if it matters!  :-)

       

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    • Posted

      Thanks for the explaination. Still. I can fill to the  300 ml mark on my beaker in 15 seconds sometimes less time. I'm thinking thats pretty darn good. Am I wrong? I will say my max bladder capacity seems to be 400 ml. Not sure if thats good or not. Last time ( 2 years ago ) my PVR was checked is was very low. Seems to me average flow rate would be a better to measure. When I check it I count from time flow starts to the last dribble. I have very little hesitation starting but I tend to dribble at the end

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    • Posted

      Yes, Uncle Fester, those are good numbers!  Your flow rate sounds like that of a 16-year-old.  I believe 250-300ml level in the bladder is typical of when the need-to-pee signal typically goes off.  Flow rate will indicate the amount of restriction in the urethra, which can be important in assessing what course of action is needed.  In your case, it sounds fine!  This is all done without a catheter, it sounds like, yes?  And... did you have a procedure to get there?  I don't recall your history...

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    • Posted

      UF: I can fill to the  300 ml mark on my beaker in 15 seconds sometimes less time. I'm thinking thats pretty darn good. Am I wrong?

      -------------------

      I filled once filled a 500ml beaker in six seconds, but I have very good water pressure at my house. Unfortunately, I don't do as well when I urinate into the beaker.

      Jim

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    • Posted

      Cartoon: Flow rate will indicate the amount of restriction in the urethra, which can be important in assessing what course of action is needed. 

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      Maybe, maybe not. You can have a below average flow rate without urethral restriction or a PVR. Probably not so vice versa. Not saying it isn't a useful marker, but only in the context of more rounded testing including PVR, etc.

      Jim

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    • Posted

      No catheter. I had minor BPH about 3 years ago. Knew I needed to see Doc about taking flowmax. Went pee at work one day. Peed blood. Not red urine, blood.Lasted for 10 days I wasn't on thinners but was taking 2 Krill oil pills a day. Not sure if that caused the bleed. Anyway, I had to get a cystoscopy done to rule out cancer which my GP, ER doc and my wife were convinced I had. The cystoscopy caused problems for me. I had pain  and difficulty peeing for months after the cystoscopy. Uro wanted to do TURP. I scheduled TURP then discovered this website. Canceled TURP and went on finasteride  I still take finasteride and cialis. I'm guessing the finasteride shrunk my prostate. CT scan showed my prostate to be 125 gr when my problems started. I don't know big it is now after 2 1/2 years on finasteride. I bleeding was on and off for about a year. Seemed to happen every 3 months weird huh? Anyway, it took about a year on finasteride but I do pretty good now. Some nights peeing is difficult most nights it not. During the day I pee great. I can drink caffine, eat moderately spicey food, eat red meat without causing problems. I'm one of the very lucky ones. I'd like to get off finasteride because it real has real screwed up my sex life. I go to the uro next month to discuss quiting finasteride

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