A New Non-invasive Micturition Graphs Measurement  

Technical Summary: A New Non-invasive Micturition Graphs Measurement

Problem Statement
The paper addresses limitations in current voiding urodynamics, specifically the reliance on invasive methods and the lack of precise quantitative assessment in existing non-invasive approaches. The authors critique the traditional "AG theory" (Abrams-Griffiths nomogram), describing it as having "logical loopholes," being qualitative rather than quantitative, and containing "suspicious areas" or blind spots where diagnosis is ambiguous. Furthermore, the authors argue that traditional methods fail to account for the physics of small flow quantities (urine) and the effects of air resistance on flow velocity, leading to imprecise calculations of bladder outflow obstruction (BOO) and expedite flow (EF).

Methodology
The study introduces a new non-invasive measurement system based on the "small flow quantity (urine) hydromechanics" theory. The methodology involves the following components:

1. Data Acquisition:

   • Participants: A total of 520 patients were measured between June 2024 and February 2025, comprising 456 male adults, 47 female adults, and 17 children/adolescents.
   • Equipment: A "commodity prototype machine" (Q-v equipment) was used. This setup combines a standard uroflowmeter (to measure urine flow rate, $Q$) with a DT-82 Mini Anemometer (to measure urine flow velocity, $v$).
   • Non-invasive Nature: The system does not require catheterization to measure intravesical pressure ($P_{ves}$) or abdominal pressure ($P_{abd}$).

2. Theoretical Framework & Calculation Chain:
   The core innovation is a "multi-parameter composite function formula chain" that derives complex urodynamic parameters from $Q$ and $v$ measurements.

   • Hydromechanics Migration: The authors migrate from standard hydromechanics (Blasiu᾽s formula) to voiding urodynamics formulas.
   • Key Derivations:
     • Flow Line ($F$): Calculated using $F = 20 \cdot (k \cdot Q \cdot \pi / v)^{0.5}$, where $k$ is a sliding coefficient ($k=Q/30$) used to correct for air resistance when $Q < 30$ ml/s.
     • Flow Resistance ($R$): Derived from $R = P_{dif}/Q^2$, utilizing a specific formula involving Reynolds number ($Re$) and urethral length ($L$).
     • Pressure Estimation: The system calculates pressure difference ($P_{dif}$) and urethral outlet pressure ($P_o$) using a tangent trigonometric function ($P_o = \tan\alpha^\circ \cdot P_{dif}$), where $\alpha^\circ$ is matched to specific $Q$ values.
     • Total Parameters: The chain calculates Bladder Outlet Pressure ($P_{ves}$), Micturition Power ($N_{ves}$), Bladder Pressure Momentum ($E_{ves}$), and Urethral Outlet Impulse Momentum ($C_{max}$).

3. Visualization and Standards:

   • Micturition Graphs: The software generates four distinct graphs (Q-R, P-Q, P-v, v-Q) displaying the relationships between these parameters.
   • Standard Curves: The study establishes specific standard lines and "boundary rules" (Left-leaning boundary rule for $R$ and $F$; Tennis boundary rule for $N_{ves}$, $E_{ves}$, and $C_{max}$) for different demographics (adult males, adult females, and various pediatric age groups) based on urethral length and physiological norms.

Key Contributions

• Non-Invasive Q-v Measurement: The development of a method to obtain comprehensive urodynamic data without invasive catheterization.
• Multi-Parameter Composite Function: A mathematical framework that unifies flow rate, velocity, pressure, resistance, power, and momentum into a single diagnostic system.
• Quantitative Diagnosis: The ability to qualitatively and quantitatively evaluate BOO, EF, micturition weakness, and compensatory enhancement, eliminating the "gray zones" associated with traditional $Q_{max}$ measurements.
• Six-Point Report: A standardized output providing six specific parameters ($Q_{max}$, $F$, $R$, $N_{ves}$, $E_{ves}$, $C_{max}$) for clinical assessment.

Results
In the study of 520 patients:

• BOO and EF Evaluation: The system successfully differentiated between Bladder Outflow Obstruction (BOO) and Expedite Flow (EF).
  • Male Adults: 267 cases were identified as BOO (abnormal), and 186 as EF (normal). Among BOO cases, 208 showed abnormal micturition power ($N_{ves}$), with 170 showing weakness ($N_{ves}\downarrow$) and 38 showing enhancement ($N_{ves}\uparrow$).
  • Female Adults: 41 cases were EF (normal), and 6 were BOO (abnormal).
  • Pediatrics: 15 cases were EF, and 2 were BOO.
• Diagnostic Precision: The results indicate that the method allows for the precise determination of the degree of obstruction and the status of voiding function (weakness vs. enhancement) using the calculated parameters ($R$, $F$, $N_{ves}$, etc.).

Significance and Claims
The authors claim that this work represents a transition from the "non-digital era of old invasive voiding urodynamics" to a "digital era of new non-invasive voiding urodynamics."

• Theoretical Advancement: The paper posits that the "small flow quantity hydromechanics" theory provides a more rigorous physical foundation than the AG theory, offering scalar and vector units for all parameters.
• Clinical Utility: The authors assert that the new micturition graphs provide doctors with a "very good theory and method" for voiding function diagnosis, offering a complete, non-invasive alternative that covers all age groups and eliminates diagnostic blind spots.
• Scope: The system is presented as a comprehensive tool that not only diagnoses obstruction but also evaluates the energy and momentum of the micturition outlet, potentially guiding the assessment of voiding efficiency.

Note: The paper explicitly states that the equipment is currently a "commodity prototype machine" entering production procedures and is not yet available for commercial sales or circulation.