Master Class - Urodynamics

I'd like to thank everybody for um participating over these uh Last, uh, morning session and yesterday, um, one of my privilege and honor is to introduce a, a former, uh, teacher of mine, and I still a teacher of mine. Uh, with our master's class in, uh, urodynamic studies. Uh, and I'm referring to, uh, Doctor Israel Franco, who, um, who I was introduced to during my training in New York. But he now is currently at, uh, the Yale School of Medicine. He's the director of the Children's Bladder incontinence Program. He is a clinical professor of urology. And, um, Uh, I think that one of Doctor Franco's strengths is a lot of his knowledge outside the clinical medicine and in the sciences. So, I urge you to all pay attention. We'll still have our ways of, uh, fielding questions in the chat box to uh present to Doctor Franco. And uh also have an opportunity to go over some clinical cases that I'll present following uh his lecture. So, without further ado, Professor Franco, I turn the uh Mike, to you. Ryan, thanks. Uh, good morning, good afternoon, good evening, good night to all of you. I, I see that we have a Uh, worldwide, uh, Yeah, group of people here, uh, which is, I was speaking with Pramud about earlier, uh, what a great accomplishment this is that we're able to extend, uh, this knowledge throughout the whole world and make it, uh, easily accessible to places that normally would not be able to go to some meetings and, uh, As my, uh, I'm actually very seriously thinking about applying this to our next upcoming meetings, um, for the International Children's Continent Society as well. I'd definitely like to thank Pramud and Eugene Brian for this invitation to talk about it. And as some of you may be aware, I tend to look at problems. With a different lens and don't always accept the conventional uh wisdom and my history on how I view voiding dysfunction and Lutz has, uh, since 2007. Has, uh, borne out to be correct, where with the ever-increasing use of functional MRI and the role that, uh, the brain has played in avoiding dysfunction and looking at these things, um, And applying the same rigor and thought patterns um that I did to avoiding dysfunction and uh You know, uh, my favorite philosopher is, uh, Spinoza, the Dutch, uh, philosopher who, um, my namesakes, uh, in, in Holland, uh, were responsible for excommunicating him, um, and using that rigor, I'm gonna apply some of that down, um, and, uh, bring an, an approach, uh, to the Uh, evaluation and how you're gonna read urodynamics, uh, both invasive and non-invasive. So with that, let me, um, start if I can get the first, there we go. So, invasive, uh, urodynamics is broken up into two categories, and the first, uh, category is, um, non-invasive urodynamics and, um, That is um primarily history and diaries and uroflammetry, but also I think we have to include in there post-void residual. The addition of post-void residual has really revolutionized the whole management of dysfunctional voiding. When I came back uh from my fellowship in Chicago with Casey Furlitt, and they, the Chicago group was one of the first groups that was using Uh, ultrasound machines in their clinic and evaluating patients at that time. Um, and I think that really revolutionized the management of voiding dysfunction. The other, uh, invasive urodynamics is when we measure detrusive pressures as well as, uh, abdominal pressures, and that's invasive, obviously, um. We use, uh, urodynamics to try to assess lower urinary tract dysfunction in children, uh, and we look at, uh, are looking for either anatomical abnormalities, uh, and we use it in, in children with neurological abnormalities as well as anatomical, uh, issues. And why, why should we do these studies? Well, it gives us a better understanding of the signs and symptoms, um, And we can establish, uh, and it should be able to help us establish a diagnosis. It can give us some guidance with regards to management. Can we measure effectiveness of that management, and we should be able to objectively measure that, um, and in some cases, it'll allow us to change or tell us to change the management of these patients. We should be doing all of our urodynamic studies with some form of hypothesis. We shouldn't be doing them without a hypothesis because we need to tailor the study based on what we think that we're going to find. So just randomly doing the study, uh, or having a cookbook where someone just does a study. They're not as effective if you're the person who's doing the study and you know what you're looking for or what you're trying to elicit, and I think that's a very important, uh, issue with urodynamics, and sometimes you do a study and you can't get an answer, and it was because someone else did the study and you were not, and they weren't cognizant of what really you were looking for. Uh, it can give us reasons to change management, and neuroflammetry can help us before we, uh, take a child and take them to do an invasive study, it can, uh, prime us, and it, in many cases, it can prevent us from having to do, uh, urodynamic studies, and I am not a big believer in doing urodynamics for a lower urinary tract dysfunction. Uh, I'm a big believer in, uh, neurogenic patients, but I find that, um, if you do good uroflowometry, especially with EMG and dual EMGs, just about almost all your diagnoses can be made without, uh, going to, uh, urodynamics. So the first thing I'm gonna talk about is uroflotry. And the, uh, what we'd normally look at is the flow, uh, the shape of the flow curves, the Q max, Q average, uh, the EMG lag time, which is for some people a relatively new concept and even a newer concept is the flow index which I've introduced in 2015. Um, So, the biggest problem with euroflowometry is that many of the curves are not standardized. This is a representation of a standardized curve from the ICS document on standardizations for urodynamics. And here you can see that um the Uh, y axis is, um, it should be 10 mLs per second per 1 centimeter, and on the x axis, it should be 10 seconds per, um, each, um, per centimeter on the x axis, and that's how all the curves should be, uh, printed. Unfortunately, all the curves are not printed this way. They are printed. Um, to fill up the page, and this is a major problem which leads to either the lengthening of curves or the flattening of curves, um, and then it leads to misreading of, uh, curves when you try to apply it across different readers and recent paper that we, uh, published by Jose Nero. showed that um in a worldwide study, um, the rates of reproducibility were astoundingly low and um we have really no, we can have no confidence that someone else is reading a study uh somewhere else and I'm reading it and that we're both gonna come up with the same answer. So this is a big problem and uh I'm, I'm gonna show you how Uh, we're trying to fix this. So this is a Euroflow curve, and you can see the curve here. Obviously, the, uh, volume divided by the time that it takes is very simple. That's the average flow and the Qax would be here. And notice that the time to QMax tends to occur at about the 1/3 mark, and I'll show you why that tends to happen. And then, Um, we see that the area under this curve is actually the volume because if we take what's on the Y axis and and multiply it by what's on the x-axis, it's actually mLs. And so this is, uh, the area under the curve is that volume. So, uh, this is just one simple thing. Here are flow shapes defined by the International Continent Society in the last document that was published in 2014, which, um, Paul Austin was the head author and I was on that group of authors. Unfortunately, if you look at the top three curves, that's it. This is what the description is. It's a picture, nothing more, nothing else, um, and everyone is supposed to adhere to this and try to figure out what a bell or a tower curve is, which is the second one, and what a plateau is. So we have no guidance and even in the best case scenarios. Um, when I compare myself to my nurse practitioner that's been with me for 20 years, we have a 55% concordance rate. So it's, it's, it's astounding how, uh, there could be so much variability in reading, uh, euroflows. The only studies that do have some, uh, quantitative methods of defining them. are the staccato curve, which is this curve here, the C curve, and uh when we do that, we measure the Um, We measure the maximum flow rate. We take the square root, and the square root of that is going to be 5.2, so the drop should be at least 5.2, which in this case, it's very clear that that drop is much more. So we can call this clearly and safely a staccato curve, and, but this is the only quantitative measure that has been introduced into the Um, ICS document. Here's an interrupted flow curve, and this flow curve, uh, you, by definition, it must come to a complete stop, so you must hit, uh, zero for it to be considered an interrupted flow curve. That's it. These are the only criteria. So right now, I'm working with the SPU, uh, voiding dysfunction Task Force to Essentially come up with quantitative criteria to define these flows, and I'll show you eventually what uh we're probably going to end up with uh down the road. So, here are the uh standards that most people have used for a long time, which is that CA should be equal to or greater than the voided volume, the square root of the voided volume. And uh that's great, but this is absolutely wrong, it's inaccurate and only applies uh to flows uh where the patient is a perfect voider and has no post-void residual. Similar EQ average, uh, Approximates the voided volume to the 0.42 power. Again, this is only applicable to a perfect scenario and then starts to fall apart as the volumes get higher or the post-void residual goes up. So, how can we, uh, look, uh, and try to figure out what the flow rate should be. Uh, if we apply a, uh, you know, a, uh, first-order, uh, decay equation and, uh, look at that as the, we approach the asymptope, uh, we're gonna approach maximum velocity, uh, for an expected volume, and, um, in this case, uh, that's well defined here, um, where by the M. The actual velocity is here, so there is, there is a constant that will lead to a decay or to, um, and then eventually, you see this uh flow over uh maximum velocity, which eventually you're gonna see repeated again later on, and it seems to be a recurring theme, which is a flow index, and I'm gonna talk about that. Uh, down the road. So, how does a normal person void? Well, these are multiple voids, um, in the same person, and you could see that as the volume goes up, the, uh, flow curve, uh, starts to slow down as the volume increases, and this is, if we look at this, this curve is not. An asymptotic curve, it doesn't follow that um equation that I showed you. Uh, it doesn't follow a power equation. It follows a quadratic equation. And then here are multiple people with multiple voids, and you could see the majority of them void in an identical fashion, and this is, um, work done by Van Garelt in his earlier treatise on uh uroflowometry. So, If we then look at the equations that I showed you before, the 0.5 and the 0.6, and even 0.66, which is later on, uh, will surface, uh, with Derek Griffiths use this, um, you could see that these equations, they tend to continue to go up, and that's A, uh, characteristic of power equations. On the other hand, in reality, these curves look more like real, uh, the curves that I showed you before, and these are quadratic equations that we generated from normal voiders, uh, from over 600 normal voiders, and one is for, uh, maximum flow in males, and the other one is for maximum flow in females. So, you know, if we start looking at the voiding uh characteristics as a mechanical process, then, you know, we start to see that the bladder neck, uh, the bladder pressure increases just prior to voiding while the bladder neck is still closed, and then this elevated pre-micorian pressure rise may suddenly stop increasing or diminish as urine begins to flow. And this is a result of two phenomena, the conversion of pressure work into kinetic energy and the natural limits imposed by muscle mechanics. Both these phenomena easily understood based on the first law of thermodynamics, and we end up with this. The Truser energy per unit volume, uh, formula, which really looks at and, and includes, uh, bladder pressure and then a flow, uh, characteristics which are tied to the viscosity and the flow velocity. And, um, when You know, we take this into account, muscles behave, will behave like ordinary power sources, so we can apply these, um, formulas and then, uh, and that they exhibit an inverse relationship between the applied load and the velocity of response and therefore, uh, this increase in flow is accompanied by a reduction in bladder pressure, um, so of pressure in the bladder. So. Moving one step forward, if we then move to the 2nd law of thermodynamics, we developed the continuity equation, which then is stating that flow rate is really, is related directly to the volume of urine remaining in the bladder and the contraction velocity of the detrusor, and for those that are interested, here's the, you know, the, the The derivative, and here's the formula, and eventually what we get is, is that uh the contraction velocity uh and a constant um are all uh play a critical role, but the most important thing is, is that this volume is really the volume in the bladder at the time that the patient is voiding, which means that it's not the voided volume. That is going to dictate the flow velocity. It is the um volume in the bladder at that time. That means it is the total bladder capacity, and this is a very important characteristic. The other important characteristic and, and based off of that contraction velocity formula is that if you look at multiple voids, All of them tend to reach maximal contraction velocity of 50 mLs at around, um, at, at around 50 mLs and that means that it takes time for urine to achieve that. So this way, when we look at a normal flow curve, we need time to reach Q max, and this explains why we see that Qax always occurring. Around 0.3 or 0.4 of the total time um that the patient is voiding. So this is an important characteristic and, and, and defines that, and it's based on the resist the outlet resistance as well. So if we take and this a little bit further and we go and uh we extend this. If the detruser is capable of generating an average force along the circumference of the bladder. The power generated by the intruder can express can be expressed as TVC and the power delivered by the urine is. The flow times the pressure, then it's, we can derive a formula that tells us that the tension in the bladder is proportional to the power, to, to the pressure in the bladder as well. So when pressure uh in the bladder, this allows us to use this as an index of bladder tension regardless of the shape of the, of the bladder. So if we now start looking at this and we can take any flow. Essentially a euroflow and then start to break it down and it can start telling us a diagnosis. And that's, and this goes, relates back to that hypothesis of what are we looking for if we're going to do urodynamics and that, uh, so if we have a detrusor energy per unit volume that is um elevated, we're gonna expect To see elevated bladder pressures or we're expect to see elevated uh voiding velocities. Uh, if that pressure in the bladder is decreased, we should expect to see either a decrease in the pressure in the bladder or we're gonna expect to be seeing a decrease in the, uh, velocity. When it's neutral, we can either see increases in pressure within a concomitant decrease in velocity, and if that's the case, uh, that would then be an obstructive euroflow curve consistent with someone who has Bladder neck dysfunction, external sphincter dyskinesia, or a stricture, and then similarly, someone who has a, uh, weakened or uh diminished ability to contract their muscles is going to potentially have um A slow void or a plateau void, or in the other case, uh, if the pressure is held steady, we would expect to see an increase in velocity. So by understanding the physics, we can understand what to expect, um, when we go do urodynamics and uh that is critical, uh, for us. The other thing that uroflowometry does, um, or that, uh, is commonly measured is, uh, voiding efficiency, and voiding efficiency is commonly determined by, uh, the voided volume divided by the, um, total bladder capacity. And this is how it's been defined, but In reality, let's, let's look at efficiency from a physics point of view, and typically, when you're evaluating um efficiency based on that, you're gonna compare actual work done by something to the Uh, theoretical work that it could do. And in that scenario, um, we can start to take and break these formulas down where the work, uh, here is really, uh, force times the velocity, and then if we replace work for the pressure and the flow, Eventually, we can get flow is the work divided by the pressure, and if we hold pressure steady, um, this pressure, these pressures drop, and then what we end up getting is that work, actual actual work divided by estimated work here, uh, is the actual flow rate divided by the estimated flow rate. So what we have is the voiding efficiency is the flow index, which we had created uh before. So our flow index that we have created to measure voiding is actually a thermodynamic measure of voiding efficiency, which in my opinion, is a much better method of evaluating efficiency than simply using um voided volume. So, With that, there was a prior precedent for this as well in that Derek Griffiths tried to describe efficiency as Q max by the uh voided volume to the 0.66 power, um, but again, in this case, he he missed the boat by not uh measuring the, the, the volume, the total bladder volume. So, Similarly, Van Garelt uh talked about these indexes, and he used Qax over the square root of the voided volume as well as Q average. Um, and then these are, um, not, uh, accurate, and, uh, I've done multiple iterations of these formulas and done error analysis on them compared to the formulas that we've developed in these formulas are nowhere near as accurate as, uh, the formulas that we have. So in the end, The flow index, besides it being a measure of voiding efficiency, besides it being able, and in a previous paper I've shown that it can be used to define flow shapes, it is also a mathematical means of making flow measurements volume agnostic. And that's very important because if you make something volume agnostic, it means that you, uh, don't, you, you can compare every study that you've done in a particular child, irrespective of the volume that they voided and their age, and you can compare uh studies in males to females as well, um, because it no longer becomes, um, volume dependent and it doesn't become sex-dependent as well. So these are, it's a very important and powerful tool to quantitate what we're doing in neurofilometry. So how did we create this, uh, flow index? We Uh, created a, uh, took bell curves out of 600 females and 600 males. We looked at the post-void, uh, residual, make sure it was under 20 cc's. We looked at the void, uh, made sure that they had a voided volume that exceeded 50 cc's, a bladder volume that did not exceed 115% of EBC because we know that that will lead to a reduction in flow velocity and then, uh, made sure that we looked at the total bladder capacity. For you, for the skeptics in, in, in the group here, the ones that say, oh, you have to have uh at least 150 cc's of voided urine to do a urine flow or that you need to uh void at least 50% of the estimated bladder capacity, that's nonsense. Uh, 50 cc's. On error analysis throughout all different formulas that were created is a gives us a very small error between different voids, less than 5% error in expected uh flow rates. So, um, 50 cc's is more than adequate to do a Euroflow in a child, especially in a small child. Here are the uh cumulative flows uh that we use to develop these formulas, and then the formulas are attached. These are the average and max male flows, uh, these are the average and the max, uh, female flows. Um, these are the actual formulas. They're described in the paper, um, here, but if you are interested in measuring flow indexes, the flow indexes are Um, essentially, you can download the app from the, uh, Apple Store. It's free, um, and if you type in pediatric urofluometry, you'll get the app, uh, and that app will calculate flow indexes for you. Uh, if it, in, in the very near future, Prometheus is going to be including, uh, in their, uh, software, uh, Uh, the ability to calculate flow indexes and it will give you curves, uh, based on percentiles, um, so, uh, based on the, the standard deviation, so you'll be able to, uh, see if someone is an abnormal voider immediately after they void. And this is based on, uh, this study, um, by Agarwal that looked at, uh, adult males and then applied a flow index. Um, their flow index that they applied was the voided volume, the square root of the total bladder capacity, and, uh, what they ended up finding was, uh, important in that. The, uh, if you take one standard deviation from the norm, all the abnormals tend to cluster in that one standard deviation irrespective of the nomogram that you use to map them on. So, uh, and the flow indexes were accurate. Uh, with AUCs in the high 90s, um, in predicting these abnormal voiders. So, um, the, the indexes becomes a very powerful, uh, quantitative tool, uh, for these patients. I'm gonna move on from index to lag time and lag time was first described by uh Kenny Glassberg and Andy Coombs. They didn't, um, they described the EMG lag time. We, there is a urodynamic lag time. And the EMG lag time is simply a simplified version of that where they look at the time interval before the pelvic floor relaxes, uh, before the initiation of volitional voiding. And this has become a very powerful tool in identifying patients who have bladder neck dysfunction, and one of the primary reasons why I find that it less and less that I need to do video urodynamics on my lower, uh, on my patients with LUTS. And, uh, if I utilize this in many, in many cases, I can make a diagnosis. Um, so, here's a euro flow and the standard lag time is 2 to 6 seconds, uh, before initiation of flow. Here's the standard flow, um, and in this case, uh, we, uh, look at this point here where the relaxation occurs before the initiation of voiding, and in this scenario, we have a lag time that is, uh, longer than it should be, uh. For this patient. Um, and on the next, uh, study, you could see that we look at the initiation of voiding here and then we work our way back. This is, um, the pelvic floor EMG in this case and it Here, this spike is the final relax uh spike before the sphincter relaxes, and it's 10 seconds before that sphincter relaxes. And what's interesting is, is there's some abdominal straining that's occurring in this patient to initiate voiding as well. So we know that this patient, and then if we take a look at the flow index, and we uh combine. Lag time flow index, we see that this patient has an index of 0.23. If we would have been defining this as a plateau void, um, it would have been a, uh, the lower limit would have been 0.7, and here we have an index of 0.23. So this patient is voiding. 23% at 23% of what a normal patient should be voiding as far as their voiding efficiency, and this is an important characteristic. Um, if you were to give this patient medication, say something like Flomax, you could immediately follow this patient and see uh the rise in their flow index irrespective of the volume that they voided. Uh, in this case, they had uh 650 cc's and even if they voided 200 cc's and the flow index went up to 0.4, you know that the Flomax that you gave them, um, Worked, and this is an important means of quantifying effectiveness uh for the treatment with medications and uh this is the value of quantifying uh the urodynamics. Similarly, we have short lag times and this is what Kenny Glassberg describes as I dodd, and in this case, you could see that the interval between sphincter relaxation and initiation of voiding is quite short. Um, don't be fooled by these. Uh, that is a wag artifact, and wag artifacts are, will always look like this. Anything that looks like it does not have a curve to it, cannot be real, OK? So just keep that in mind, um, and then when you do go ahead and figure out where the Qax is, just fill in the lines and like this black line, so your Qax would have been here, not this, and by changing the Qax, you could see that the real Qax flow index was 0.93, not 1.58. Uh, but in this case, This is still a tower void because this is the flow index for the average flow is 1.58. Um, so, we know that the flow index. The average flow index dictates really the shape. And, in a present study that I'm working on right now using principal component analysis and discriminate analysis, we clearly can see that the uh flow index is um tied to the, the average flow index is strongly tied to the flow shape as well as the time to Qax. So, The big question here, is this a normal lag time or isn't? And this is one of the inherent ambiguities of uh lag time, all right? Is the lag, do we measure the lag time here or do we measure it here, OK? And this is a problem, and I'm not gonna say that lag time is without, that it's perfect and that it's not imperfect. It is, and the other question here is, is a tower or a bell. So, how can we discern this, right? And, you know, if, if we call it here, then this would be a just slightly normal lag time, OK? It's for um And then if we look at the flow index, the average flow index was 1.24, so it settles within the uh bell curve, uh, as far as that goes. But in reality, if the flow index ended up being here because this was artifact that was due to abdominal straining because the patient was trying to strain. Which we would have picked up if we did a two-channel EMG, then we would say that the EMG, uh, lag time was, uh, could be measured from this point. So, again, it's not perfect, but it does work in the vast majority of the time and it can really be of value. Here's another example of measurement of lag time, um, and you can see here that Qax is reached in a relatively normal time, but this is a long, prolonged lag time. Uh, and in this patient, they're very abnormal voider, and then, uh, when we did the urodynamics in this patient, she generated a very powerful contraction early on and then the contraction died off very rapidly, leaving her with an elevated post-void residual. So, Her potential energy in that the truser was actually uh not as high as it needed to be to generate all the kinetic energy that she needed to drive her uh urine out. So, and, and, and this last example is this a tower or a bell. Uh, here we see a short lag time again and we look at the numbers, you could see maximum flow is 44. Um, these, uh, nomogram numbers that you see in the library, um, Uh, program are, uh, typically, uh, of no value because they're based on adults. They have nothing to do with children, so just keep that in mind, beware. Uh, but in this case, this is clearly a tower void with an average flow index of 1.68. So, now let's move to invasive urodynamics. And why do we need invasive urodynamics, OK? We need to uh occasionally be able to establish, uh, a diagnosis in patients who have neurologic problems or congenital problems or in patients who have LUTS, and, you know, it's valuable in our atrophy patients, anal rectal malformations, tethered cords, and even patients with cerebral palsy. And keep that in mind that if you really investigate patients with cerebral palsy, Uh, 70% of those patients are gonna have some type of, um, lower urinary tract dysfunction. So, um, don't assume that just because they don't wet themselves, that they don't have a problem. So, uh, that's just a little, uh, sidebar. Um, in patients with LTS, uh, pre-screening with non-invasive urodynamics, um, helps us, uh, You know, uh, evaluate patients who may have obstructive, uh, problems and dysfunctional flows, uh, recurrent UTIs, you know, do, do you evaluate the patient with dilated ureters or patients with Elevated post-void residuals. Obviously, if you wanna do a patient with LTS and you're interested in doing a VCUG then it pays to do uh video urodynamics, and then looking at patients with resistant lower urinary tract dysfunction. What's interesting is, is that there are no formalized guidelines um that exist to say when you should be doing fluoroscopy in urodynamics. So it is strictly up to you. My off the hand, um, method of doing it is My first study is almost always with video, uh, in all my neurogenic patients. If I'm simply following up to do an assessment of management or treatment change, then I don't use video. Um, or if I'm evaluating for urinary leakage, then I'll tend to, uh, be doing video in neurogenic and non-neurogenic patients. Um, What's the value of video? Looking for reflux, bladder wall abnormalities, diverticula, bladder neck, uh, bladder neck and the outlet abnormalities, valves, stenosis, uh, hypermobility and hyperlaxity, uh, so all these things. And what are the issues with video? There are drawbacks uh related to the radiation, the cost of the study, anxiety. Uh, you get little kids, they get freaked out by the big uh collimator that sits in front of their face, um, and then, uh, obviously, uh, the advantages are that we can combine function and anatomy. So, what's a urodynamic curve? Well, urodynamic curve is simply a pressure time curve, OK? And that pressure time curve, um, really ends up being truly a pressure volume curve, OK? Because if you hold your, um, You know, your, your, your infusion pump is set at a steady rate, time really becomes equivalent to a volume, and that is a uh critical component because when we look in thermodynamics, we, we're always comparing pressure volume curves, and a pressure volume curve is, uh, the area under a pressure volume curve ends up being work. So, uh, this ends up being a very important Uh, criteria. When it comes to urodynamics, uh, most urodynamic machines are set up, um, with the, um, vesicle pressure on top, the abdominal pressure here, and then the detrusive pressure here. By the way, there's, um, a new player in video urodynamics, uh, which is Prometheus, uh, they've developed a new video urodynamic machine. Um, and this is their most recent, uh, machine where you can, images are captured automatically, uh, as you are doing the urodynamics, so there's no need to capture, uh, press a button to capture images. But I like to actually set up my machine, uh, in this way where I, I put my abdominal pressure and my vesicle pressure on the same line. Uh, and this way, I can see very closely the temporal relationship between the abdominal and vesicle pressures because in some cases, when you see that they're at a phase, um, then What it tells me is, is that if, especially if the uh abdominal pressure uh spikes and then the vesicle pressure spikes, I know that the rectal contractions are contributing to bladder contractions. Um, and that sometimes becomes very Important because if I see that, then I know that I must clean that patient out, that they're inadequately being treated for their bowels and um so this I find helps me more than uh the other way that the screen was set up. So it becomes, obviously, it's a preference, but uh this is uh a little quirk and something that I learned along the way that is uh valuable. Um. So, what happens? How do we interpret urodynamics? It's pretty much basic, uh, uh, common sense stuff. Um, we have the vesicle pressure here. Oh, so, um, normally we would expect the bladder to fill, OK? And as the bladder fills, abdominal pressure should be flat. And that means that we're subtracting the abdominal pressure from the vesicle pressure. If we subtract zero from this, we get this. So this is our vet deep debt curve. This line here is um the urethral pressure curve, and I'm gonna describe this because uh Pete Hobecky and his group in Ghent. utilizes this. He uses a three-channel, uh, catheter and leaves one, the proximal channel, uh, in the, uh, uh, the distal channel in the, um, urethra in the bladder neck area, uh, distal to the bladder neck, and, um, so here is the urethral pressure, uh, and you'll see, uh, the effects of that. So, We then, uh, go through, um, This and see that uh P debt, obviously, as I said, is a function of PVEST minus PA and there's no flow. Um. Here we got uh what looks like or could be detrusor overactivity, um, and you see these, and you see this contraction, and, um, but there's no increase in abdominal pressure. That would be qualify as detrusor overactivity, OK? Um, What we then see is um the same type of picture. Uh, there's no change in the trees or overactivity, uh, but can this be an overactive contraction? So, what you should do is, you know, when you Along the way, as you're filling, every once in a while, try to valsalva the patient or have them cough. In this case, you see, there, the pressure curve is not in the abdomen, it's not picking up, and that will tell you that uh these are not real, uh, or you can't tell that these are really true. The truths are overactivity. So it's essential. If everything looks quiet while you're filling, to always check and make sure that you are confirming that you're still uh measuring pressures adequately. And if you get, especially in the spina bifida population that has massively distended rectums, uh, or sigmoids, and they got a clean out, uh, it's possible that the catheter, the balloon catheter won't be making. Uh, contact to the, um, bowel and you can drop your signal, and if that happens, you'll get a scenario such as this. Um, and then when that happens, uh, you have to be aware and not make sure that you're not making it. And that's why whoever is doing the study is very critical and that they document everything that's going on. Here's another scenario where you Get the appearance of an overactive bladder contraction. You see this in the PDE picture, um, and then you don't see, uh, uh, an increase in PVES, um, so that should tell you, you look here and there's a drop in the pressure. Could that sometimes will happen. The patient moves, the catheter moves, and no longer is, uh, fixed to the abdominal wall, and you get that pressure drop. So this is a spurious, um, Event and it is a, uh, looks like a contraction, but it is not. So, um, and again, you can confirm it, um, by making them cough and proving it, uh, that way. So, it's a true overactive bladder will uh be associated with no abdominal activity, overactivity, and typically, if you're monitoring the urethra, there's gonna be an increase in urethral pressure as well with some leakage, and uh this is uh exactly what tends to happen in these scenarios. Um. So, this is uh what I, uh, with, uh, my good friend Walid Farhat uh calls a cryogram, um, and, um, you know, um, but, so I saw this infant, uh, uh, a week or two ago and was seen, um, By somewhere, uh, somewhere else and they read this as a small bladder capacity, no reflux, the trus are instability throughout the exam, no sustained pressure elevations. Um, so, you know, really, these two are identical to each other and what are we seeing here? Uh, we're seeing a completely flat abdominal curve, OK? And, um, You got a baby that's crying, you know that the baby is crying, uh, and you're not seeing abdominal pressure. So, how can you possibly say that this is detrusor instability? So, this, it's very important that you monitor that abdominal pressure, otherwise, you're gonna get a study like this and you're gonna make a Horrendous mistake. Uh, in this case, it's really not a big deal, but I've seen cases where people get diagnosed as having neurogenic bladders, especially in children who have, uh, quote-unquote, thickened phylums that end up having, uh, their cords operated on. So, um, beware, this is a common problem, OK? And Here's uh a case of involuntary voiding, uh, where, or what you would see in giggle incontinence, you get the intrusive overactivity with a subsequent drop in the urethral pressure and then flow that occurs, uh, in that same scenario. Um. Here, stress incontinence, uh, the maximum pressure goes up. You get, uh, concomitant increase in vesicle pressure. No, uh, the subtraction is normal. We get nothing here and then you do get a change in the vesicle, in the pressure in the urethra with subsequent, uh, flow. So when you're doing a pressure flow study, this is what you should be seeing in patients who have stress incontinence, um. What about overflow incontinence? Again, uh, pressure will go up, uh, continuously, uh, no change in the urethral pressure, and then, uh, pressure goes up in the pee dip where eventually you mark a leak, uh, somewhere along the way. Um, this, uh, cartoon shows you the abdominal pressure being low, but in some instances, as the bladder continues to increase ever so more, um, this pressure can actually go up somewhat, um, as the bladder is filling. So that's, uh, something to keep in mind when you're doing these studies. So, when do you stop filling? And uh this could end up being a controversial topic. Um, the standard, uh, that most people will tell you is um when the patient hits 40 centimeters of water pressure, um, or they've achieved their estimated bladder capacity. Uh, I don't think that that's the case. I, uh, and I could tell you, having been involved in multiple clinical trials where we were looking at, uh, testing, um, some of the drugs that were being tested probably could have been, um, uh, would have had better data if we actually, uh, didn't follow those criteria. The first one is persistent leakage um that's not associated with the choose or overactivity. Simple little contractions uh that cause leakage, you can continue to fill them, especially if you're below certain estimated parameters, uh, that I'll talk about. PVAS of 40. is what normally people say. The problem is this, if you, you have to take this into context. If the patient Uh, cats in the morning and has 800 cc's in the bladder. And you reach PVS at uh 400 cc's or you reach a PVES of 40 at 400 cc's, you have to know where that patient lives between 400 and 800, OK? If you stop the study. At 400 cc's you're gonna say, oh, this patient's OK, OK? And you're not gonna be able to explain why they're having persistent urinary tract infections or why they're having persistent renal scarring. You have to continue, OK? And that's why in all my patients, I wanna know what their maximum volumes are and have them record their morning cath volumes. And this way, I know how far I need to fill these patients because if you just use the estimated bladder capacity for age or if you use just pressure of 40, you're gonna leave information on the table that you would have been very important for you to make a diagnosis. Again, uh, you can, you should stop when they're uncomfortable or they're feeling very full. I don't think that's, uh, difficult to, uh, understand. And then, um, you know, don't use necessarily expected capacity. Uh, try to use known bladder volume, OK? Um, and if the patient has a very compliant bladder, and you go past their known bladder volume, Um, then, uh, continue filling until you perceive that the patient is, uh, uncomfortable or is showing signs of irritability. Uh, in some cases, some children will actually, their legs will start to shake in the neurogenic patients. So, these are the criteria that I used to fill that help me define how to manage these patients, uh, and obviously, when they, they leak. Um, compliance is a big problem. How do we measure compliance? Well, we wanna know the, uh, it's pressure over volume, uh, or it's the volume over the pressure, and, uh, in this case, this is the incorrect way to measure compliance. Um, you're measuring it at the height of the contraction. Um, and that, uh, volume would, you would take the pressure here, OK, and then, um, You don't wanna take it here, um, and that is the incorrect pressure. The way to do it is to, um, take it, measure it just before the contraction begins, OK? And Uh, measure the delta between the pressure here and the rise in pressure here. You would be amazed at the number of incorrectly measured compliances, um, that Pete Hobecky and I, uh, encountered while we were doing, um, readings of urodynamics for clinical trials. Um, just about 50% of them are, are incorrectly read. Whether they're incorrectly read by a urodynamic machine, or whether they're read incorrectly by the reader. So, uh, that's a, a big, uh, problem. So, you know, what happens during voiding, uh, here's a nice normal compliant curve and then pressure goes up, and, uh, you can see here clearly that the urethral pressure goes down and uh maximum velocity uh is achieved. Obviously, when maximum velocity is achieved, then what you end up having is an increase in the pressure in the zone. Um, which is to be expected, uh, at that point, uh, from flow equations, and then the pressure gradually drops as the maximum velocity goes down and the contraction velocity in the bladder is going down as well. And you can see, um. And here, again, this is a cartoon of normal emptying. You can see this drop in um contraction velocity uh or the urethral pressure with an increase in the voiding um velocities uh on the flow. And remember, uh, the bladder neck has to open, uh, for the initiation of, uh, flow as well. And then, uh, in overactive bladder situation, there's gonna be persistence of this urethral pressure being present, um, the flow will initiate, and then subsequently, uh, there's relaxation. So, um, this is what we tend to see, and this is what gives us that tower void, and again, that's where the, um, VE over DT uh issue comes in, in that, uh, equation. And again, in, in an undiractive bladder, we're not seeing a We're seeing straining, uh, with the straining, there's changes in the urethral pressure, uh, which is why we don't like patients to Valsalva to empty their bladders because in some cases on Valsalva pressures can exceed 200 centimeters of water pressure in the urethra, uh, so it's ideally not the best thing for them to be doing. Um, and then there's no contraction of the detrusor, so, um, we get, uh, very little or poor flow. So, urodynamics, uh, has problems and pitfalls. Uh, one of the main problems is measurement of compliance, and people utilize that measurement of compliance as a primary means of, um, Measuring things and uh the other issue is measurement of and filling pressures and there's uh, so is there a better way of comparing one study to another? Um, and that is by measuring urodynamic work. And the urodynamic work, remember I said is the area under the curve. We, I developed a software program that allows me to split this work into Um, the area, uh, above this white line, which I call the trusa work, which is what detrusor contractions are, and then what we call the vesicle elastic or the constant tonus, uh, that involves smooth muscle and, uh, um, the collagen. Um, on the other side, if we take to work and divide it by time, we have power. So, We created a software program. It's available if anybody wants to have access to this program, uh, just email me. You'll get my email at the end of this talk. Um, it measures work and I'll show you it, uh, you go in, you hit studies, the studies will pop up here. Uh, you hit view study, you pick, um, Add file to study and you can add files and then once you have your files added, you hit process test and uh this is where you would add your file. Choose a file, you download it and it will be downloaded. The files have to be in, if you use Library or Prometheus, they will export their data in a TXD form. Format, um, and, uh, that raw data gets imported and it generates this pressure flow curve, pressure volume curve, which then measures the total work and then gives you this, uh, spreadsheet, um. So here's, uh, we're almost done. I'm, I'm just gonna quickly go over a couple of examples, um, to show you the benefits of this. Here's a patient of mine that, uh, we started on anticholinergics and, um, Night drainage and if we look carefully here, we could see that at 550, the total work being done was about 5000, uh, and what I call the theoretical pressure was 18.4 uh compared to his actual PDb which was 33.2. Um, recently, he had a, uh, I did urodynamics on him. And um, Last week and I would say, uh, he's doing great. He's almost 700 cc's, um, and, um, everything should be hunky-dory. I shouldn't have to worry about him. Well, actually, if we start to look at this a little bit closer, the amount of work done at the same volume has gone up. It's 6200 and it's pressure has gone up as well, as well as the theoretical compliance. So, originally, I was gonna say, come back and we'll do urodynamics in 2 or 3 years, but I'm gonna bring him back next year because I'm, I have to really stay on top of him and make sure that he's not gonna start changing on me for some reason. Similarly, here's another case where this fellow was being followed by another urologist who looked at this urodynamic study and said, well, this guy, he's got no problems. Uh, he has no uh uninhibited contractions. He's holding, uh, 500 ccs. He doesn't need anticholinergics. Um, you know, and surely you don't see uninhibited contractions. You see very little work. The work here is only 7% of the total work, um, that the bladder is doing at 450, uh, cc's, um, which is, uh, where he leaked. Um, then if we go And look at uh him after he was started on um Ditropan, and we go back and look at 450, we see that we dropped his total work from over 6000. Uh, at 450 to 2400 and his pressure dropped dramatically as well. Uh, so by adding Ditropan, we significantly changed his work. He was doing 6100 of vesicle elastics, so he wasn't having detrusor overactivity, but the tonus of that bladder dramatically changed, and it went from 6100 to 1400. So there's a dramatic change in his bladder by simply putting this young man on Ditropan. Then he was hospitalized recently and had febrile infection, and uh we looked at it and here he is holding only 460 mLs. The pressure is now dramatically higher, 44. That's the theoretical pressure, and his total work is 10,000. It's gone up dramatically from 2000. So this guy, um, I pushed him, and it became clear, he stopped cathe catheterizing himself. He was depressed, and he was stopped taking his Ditropan. So, we objectively proved that this young man didn't, was, had significant changes in his urodynamics, and we were able to capture these with uh this, and we've got him back on his cats, and we'll see, and we'll prove that he's getting better on the next study. So, I think we can I have you wrap up because I would like to get some of the cases. Done, done. Oh, perfect. Well, hey hey, what, how did, how did you time that? How'd you time that, Izzy? Huh? I said, how did you time that? Yeah, that, well. So, thanks. Uh, I, I, I hope, uh, you guys were able to, um, see things in a different light and, uh, hopefully, All of us will be able to get out there and see views like this instead of, uh, you know, uh, being stuck in our houses, uh. So, Thanks, thank you, thank you, I, you know, um, as you alluded to when you began, you do look at things through a different lens, and, um, I know there are many of our colleagues on this from uh across the states and across countries. And um I think Doctor uh Stacy Tanaka is attending and Definitely a concept that uh is going around is how much inter-observer variability exists. Uh, you and Doctor Hobecky and others that have run clinical trials and multi-centers see this, uh, while you're being the principal investigators. So, I, um, find that, you know, the theoretics that you went into the beginning. Uh, are what are serving your development of some objective measurements of these tracings that in, um, sort of pediatric urologists or adult urologists, uh, workplace don't seem to be giving the, you know, we're, we're both looking at an apple, but, uh, somebody sees an orange and somebody sees an apple. So, Uh, I hope the audience was able to. Uh, focus in on some of your work for both the non-invasive and um invasive urodynamics, cause it's applying the same kind of principles. There are a lot of questions, uh, from the chat room. And, uh, some of them, um, I'm gonna hit up first that aren't specifically about the content but using your, uh, expertise as well as, uh, sort of the rest of the panel. And, uh, the rest of the panel does include Doctor Yerkes from Chicago, Doctor Defore, uh, from, uh, us as well here in Cincinnati. And Doctor. And Doctor Doherty, I apologize. What are the, um, what do you think is the contribution of a catheter? During the filling on, say, bladder activity or measured pressures, even say during voiding, um, was one of the questions. For me, sometimes I wonder if we're doing a transurethral, uh, multi-channel urodynamic study, say, in a male under the age of 1, we usually are using some type of maybe a, a 5 French catheter. But I wonder how, how much is the normal diameter. Affected of the urethra with the, the catheter, you know, will, will voiding contractions be measured higher because the bladder is trying to squeeze through a narrow urethra that you've plugged up with your catheter? Or what does the bladder itself? So, that was, that was one of the questions from the audience. You want me to answer it, or you want the panel to answer. So, there's no question that free flow urodynamics. Uh, and free flow uroflowometry and, and uroflowometry with a catheter in it. Give you completely different uh flow uh flow curves. And I could tell you because I did a study for Allergan trying to develop a um system to predict who goes into retention um after Botox injections and looking at the urodynamic flow characteristics and looking at free flow characteristics, it was night and day. Um, so the catheter has major effects on flow rates. Theoretically, the pressure, uh, at least that is intrinsically built, OK, in the system on distension of the bladder muscle, uh, and that is the, the pressure in the detrusor, um, should theoretically be the same, OK? It shouldn't matter, OK? Um, because that equation that I showed before, uh, T is equal to, uh, 0.7 to the volume 0.66 to the pressure will dictate that pressure, OK? The tension. So depending on how, so theoretically, it shouldn't change, OK? Your flow velocity will change, OK, based on the physics. Um, so, I think that's uh really, uh, now whether a catheter irritates the bladder or doesn't irritate the bladder. That's a whole another ball game and probably it does have some effect on it, um, and, um. You know, so, you know, and theoretically, the ques next question that's gonna come is, um, is, um, you know, um, natural fill urodynamics, uh, theoretically should be better than, um, uh, you know. Sure, I mean, they may be more, I, I don't know if we'll know they're better, but they're probably more representative of what happens outside of our offices. So, right, right, um, can you stop sharing your screen cause I'll have a, um, presentation of cases. Another question that came up and, uh, I may call on Doctor Yerkes while I'm loading mine, uh, for, uh, her comment, um, is, uh, Can you comment on, say, the, the reliability or the fidelity of a um, Uh, urodynamics performed under general anesthesia. You know, sometimes I'll see patients that are referred. It's not my preference to put children to sleep for urodynamics, but others may find that the patient was unable to tolerate it, or catheterization, or parental, or, so you may have encountered the same thing where a patient comes to your office, there are urodynamics performed. Why am I, why are you recommending another one? I just had one. What do you usually take away from a urodynamics that was performed under general anesthesia? First of all, You know, if you're gonna do urodynamics under anesthesia. What you can never give the patient a Muscle paralyzing agent. Number 2, you can't give them, uh, any inhalational agents, OK? Um, So if you're gonna do a urodynamics under anesthesia, the only anesthesia you can possibly do is to use propofol and nitrous, OK? Because anything else that you do will have an effect on detrusive contractility, will have an effect on muscle activity. Uh, doing urodynamics on a patient who has luts under anesthesia is essentially useless, OK? Because under anesthesia, you take out the frontal lobes and the frontal lobes are critical in the, uh, control of mictuin and in some of these patients who have Luts, the primary issue is frontal lobe dysfunction. Um, so doing a urodynamic study in a patient, uh, who has a luts, uh, under anesthesia is absolutely useless. Um, so, you know, um, we do, we do do a lot of patients with nitrous where we'll give them nitrous to put in the catheters, um, and we're very fortunate that we could Uh, they'll do that in our urodynamic suite. Um, we try to avoid, um, Versed. Again, if you use Versed in patients who have what symptoms, it becomes a problem, I find it less of a problem in neurogenic patients. So the short answer is don't do urodynamics under anesthesia. Well, um, I, I agree, and, uh, I, I think, uh, in the interest of time, uh, and, and your response to that question, uh, well I'll ask the panelists their comments on maybe some of these cases rather than again on this. So, um, mm, these will be cases that are probably gonna comment more on sort of formal invasive urodynamics rather than, uh, sort of the non-invasive, uh, variety here. All right.