Urodynamic Studies How to Perform & Interpret • Definition Urodynamic Testing in Children – Urodynamics is the physiologic study of the lower urinary tract during its 2 phases of the micturition cycle in an attempt to re-create the normal pattern of urinary storage & evacuation Stuart B. Bauer, MD – It involves both invasive & non-invasive testing to Department of Urology assess these functions Children’s Hospital Boston – It tries to accomplish this objective in the least intrusive way in order to obtain meaningful & reproducible results 1 2 Urodynamic Studies Urodynamic Studies Indications Armamentarium • Anatomic •Uroflow – Posterior urethral valves – Vesicoureteral reflux • Uroflow / EMG – Bladder exstrophy / epispadias • Cystometrogram • Neurologic – Myelodysplasia • Voiding pressure studies (VPS) – Tethered cord syndromes • Cystometrogram / VPS / sphincter EMG – Sacral agenesis – Spectrum of spastic diplegia • Cystometrogram / VPS / radionuclide • Functional cystogram – Day and nighttime incontinence – Recurrent UTI 3 4 1 Preforming Meaningful Urodynamic Studies Preforming Meaningful Urodynamic Studies Asking the Right Question • Education Preparation • What information have you gained so far from – Parental acceptance ancillary investigation (Hx, PE, imaging)? – Patient understanding • What information do you want to glean from your investigation? – Familiarization with components of study • What study would efficiently answer the – Providing pre-testing materials (handouts, facility website) question(s) posed? • Could information be gained from non-invasive – Touring the facility beforehand (virtual touring) versus invasive studies? – Discussion with other ‘veteran’ families 5 6 Performing Meaningful Urodynamics Performing Meaningful Urodynamics Urinary Flow Rate Urinary Flow Rate – Eliminating Artifacts • Definition – The real time measure of a urinary flow curve that ‘directed’ aim ‘random’ aim records velocity / second + cumulative voided volume • Optimal Conditions – Arrive ‘well’ hydrated but NOT overdistended – Bladder scan prior to obtaining flow - estimate size – Flow meter located in a private setting – Boys - instruct ‘aim’ at a specific site – Girls - provide foot support – Girls – adequate sized ‘seat’ for comfortable support Neveus T, et al: J Urol 2006; 176: 314-24 Austin PF, et al: NeuroUrol Urodynam 2016; 35: 471 ”Aiming” minimizes variations in flow rate 7 8 2 Performing Meaningful Urodynamics Urinary Flow Rate – Optimal Parameters Urinary Flow Rate – Eliminating Artifacts Foot rests ‘Seat’ opening • Volume voided > 50% of expected capacity for age: (EBC [ml] = age [years] x 30 + 30) • ‘Ideal’ volume ~ between 65 – 115% of EBC • Residual urine via bladder scan - < 6% of EBC or < 10 ml • Repeat flow rate to confirm flow characteristics • Denote time since prior void to get a sense of urine production Proper posture, adequate foot rest & seat support - Nl production = 1 – 2 ml / kg / hr helps maximize pelvic floor relaxation during voiding Chang S, et al, Neurourol Urodyn, 2013; 32: 1014 9 10 Urinary Flow Rate – Optimal Parameters Urinary Flow Rate - Types • Bell-shaped • Effect of urine volume – on flow rate parameters – Smooth rounded flow - normal • Tower – Explosive flow - 2o OAB • Staccato – Sharp peaks / troughs – Overactive external urethral sphincter • Interrupted – Discreet peaks with no flow in between peaks – Underactive bladder with straining to empty • Plateau PVR = 32 PVR = 12 – Prolonged slow flow Chang S, et al, Neurourol Urodyn, 2013; 32: 1014 – organic obstruction 11 12 3 Urinary Flow Rate Types - Examples Normal Flow Rate Bell Shaped Tower Staccato Interrupted Plateau 13 14 Predictability of a Flow Rate Flow Rate Patterns Tower Flow – Cystometrogram – Overactive bladder Max = 50 ml / sec Staccato flow Interrupted flow 15 16 4 Quantifying Urinary Flow Rates Bladder Scanner • Created ‘Flow Index’ (FI) • Reproducible & reliable means to estimate a particular flow in children without the use of a flow nomogram • Predictive of bell, plateau, & tower flow patterns • ‘FI’ is a mathematical manipulation that allows for compensation for the increasing variation around the mean with an increasing volume •FI = Qact/Qest = P⍵act/Pact)/(P⍵est/Pest) • Flow Index = Actual Qmax / Estimated Qmax Franco I, et al: Neurourol Urod. 2016; 35:836-46 Franco I, et al: Neurourol Urod. 2018; 37:1-12 17 18 Indications for Uroflowmetry Flow Rate - Conclusions • Ideal test to get a sense of bladder capacity & • Day & night LUT symptoms unresponsive to ability to empty in a non-threatening manner timed voiding & / or taking time to empty • Provides clues to bladder function & potential • Recurrent non-febrile UTI causes of incontinence & / or urinary infection • Thick-walled bladder on renal / bladder echo or • Can direct clinician to appropriate next test to incomplete emptying on post-void echo confirm type of lower urinary tract abnormality • History of straining to void or complaints of •May reveal urine production as an etiology for prolonged flow or incontinence after voiding LUT symptoms • Recurrent terminal hematuria Hoebeke P, et al: J Urol 183: 699, Feb. 2010 19 20 5 Case Presentation Case Presentation 9 y/o ♂ with several What is your next step? weeks of dysuria & a. Refer to Nephrology two episodes of terminal hematuria b. Renal Ultrasound c. VCUG Flow rate – slow & d. Retrograde Urethrogram prolonged e. Flow / Patch EMG looking for dyssynergy Flow rate was repeated 3 times with similar findings 21 22 Case Presentation Case Presentation What is your next step? a. Refer to Nephrology b. Renal Ultrasound c. VCUG d. Retrograde Urethrogram e. Flow / Patch EMG looking for dyssynergy Retrograde urethrogram – confirmed a stricture 23 24 6 Flow + Patch EMG Placement of Patches for Flow / EMG • Urinary flow rate combined with patch EMG pads placed on the perineum • Assesses activity of the urethral sphincter during micturition • Distinguishes ‘dysfunctional voiding’ from straining to empty • Directs treatment to biofeedback training versus timed voiding & other measures to improve emptying 25 26 Uroflow /EMG in two 4 y/o girls with LUTS & RUTI Both suspected of Dysfunctional Voiding (DV) Indications for Flow + Patch EMG • Staccato or interrupted pattern on initial uroflow • Incomplete emptying on initial flow rate • Cystometric evidence of voiding pressure & / or incomplete voiding •‘Spinning top deformity’ on VCUG for recurrent UTI This ♀ with urgent voiding has confirmed Dysfunctional Voiding This ♀ with only mild urge to void despite a voided volume 180% of EBC study reflects straining to void or Underactive Bladder 28 7 Performing Meaningful UDS - Cystometrogram Preforming Meaningful Urodynamic Studies • Determines capacity, compliance + presence of Cystometrogram overactivity of the bladder during its storage phase • Adherence to Protocol • Emptying (voiding) phase is part of the study – Bowel cleanout 1 - 2 days before • Performed with bladder + rectal catheters – Lower urinary tract modulating medications • Know what medications, dosage & frequency – Measures characteristics of the detrusor • Record when taken prior to study – Distinguishes overactive contractions from artifacts • Discontinuation timing if need to know change in of motion function – Have family bring favorite toy / video or provide • Fill rate / min < 10% of expected capacity • Natural fill, ambulatory cystometry is ideal but time consuming & impractical 29 30 CMG Performance Cystometrogram Performance • Attention to Detail – ‘Zero’ transducers • Importance of Rectal Pressure Monitoring – Have child void into flowmeter, if toilet trained – Empty bladder (aspirate catheter after urine stops draining) Increasing bladder pressure – Know status of upper urinary tract • Hydronephrosis & / or hydroureter • Presence of reflux – Obtain UA & send for culture • Consider delaying study if (+) U/A – Recheck all connections to pump, transducers – Have child as comfortable as possible when starting – Make sure all channels are recording • Test with cough, Credé, initially & throughout filling CMG – Never ‘rush through’ the study 31 32 8 Cystometrogram Performance Cystometrogram Performance • Effect of Bowel Cleanout • Effect of Varying Filling Rates • 38 pts underwent 3 CMGs CMG without bowel cleanout CMG with bowel cleanout – medium (20% EBC / min), slow (2% of EBC / min) then, medium fill again • Findings – Detrusor Pr. > 40 cm H2O = occurs twice rate in medium fill – ∆ in Pr. > 15 cm H2O = only occurred in medium fill • Conclusion – Bladder filling rate affects detrusor pressure measurements Joseph D: J Urol 1992: 147; 444 33 34 Cystometrogram Performance Cystometrogram Performance • Effect of Varying Filling Rate • Effect of Varying Filling Rate on Detrusor Overactivity CMG with DO – rapid vs slow fill CMG with rapid fill – CMG with slow fill – 20 ml/min 10 ml/min Joseph D: J Urol 1992: 147; 444 35 36 9 Cystometrogram Performance Cystometrogram Performance • Timing of DO – Importance of Early Observation • Timing of Adjunctive Bladder Modulating Medicines CMG with DO early in filling CMG with DO later in filling CMG 24 hrs after last med CMG 6 hrs after last med • DO can occur anytime – observe thruout the study 37 38 Cystometrogram Performance Case Presentation • Importance of Urethral Pressure Measurements A 7 y/o ♂ with frequency, urgency + day & night wetting How would you read the following cystometrogram Notice: urethral & what would you do next? instability can be a cause for urinary incontinence that may be missed when the