Related Experiment Video
Updated: Dec 18, 2025
Author Spotlight: Enhanced Urodynamic Method for Precise Urine Measurement in Awake Mice with Neurogenic Bladder
Published on: June 7, 2024
The relationship among flow index, uroflowmetry curve shape, and EMG lag time in children
Jee S Ha1, Yong S Lee1, Sang W Han1
1Department of Urology, Urological Science Institute, Yonsei University College of Medicine, Seoul, South Korea.
Insights
Electromyography (EMG) lag time in children with lower urinary tract symptoms correlates with flow index (FI) and uroflowmetry curve shape. Shorter lag times indicate efficient voiding, while longer or delayed times suggest inefficient voiding patterns.
Area of Science:
- Pediatric Urology
- Urodynamics
- Lower Urinary Tract Symptoms
Background:
- Understanding voiding dynamics in children is crucial for diagnosing and managing lower urinary tract symptoms (LUTS).
- Electromyography (EMG) lag time and uroflowmetry parameters like flow index (FI) are key indicators of bladder and urethral function.
- The relationship between these parameters requires further elucidation in pediatric populations.
Purpose of the Study:
- To investigate the correlation between electromyography (EMG) lag time, uroflowmetry curve shape, and flow index (FI) in children with LUTS.
- To determine how different uroflowmetry curve patterns relate to EMG lag time.
- To assess the clinical significance of EMG lag time in characterizing voiding efficiency.
Main Methods:
- A cohort of 294 children with LUTS underwent uroflowmetry and EMG testing.
- Curve estimation regression was used to analyze the relationship between EMG lag time and FI.
- Patients were categorized based on EMG lag time intervals and uroflowmetry curve shapes (tower, bell, plateau, fractionated).
Main Results:
- A significant cubic relationship was observed between maximum FI and EMG lag time (R² = .282; P < .001).
- Children with shorter EMG lag times (0 to <2 seconds) exhibited the highest mean FI, suggesting hyperefficient voiding.
- Prolonged (>6 seconds) or delayed (<-4 seconds) EMG lag times were associated with lower FI and patterns like plateau or fractionated voiding, indicating hypoefficient voiding.
Conclusions:
- EMG lag time is closely associated with FI and uroflowmetry curve morphology in children.
- A lag time near 0 seconds correlates with a tower-shaped curve and hyperefficient voiding.
- Prolonged or delayed lag times are linked to hypoefficient voiding and plateau or fractionated flow patterns, offering insights into voiding status.
Purpose:
To determine the relationship among flow index (FI), uroflowmetry curve shape, and electromyography (EMG) lag time in children.
Materials And Methods:
A total of 294 children with lower urinary tract symptoms were included. The overall relationship between lag time and FI was investigated with curve estimation regression. Normal and primary bladder neck dysfunction was defined according to the previous classification, while patients with a lag time less than 2 seconds were grouped based on 2-second intervals. We also categorized cases into four groups (tower shaped, bell shaped, plateau shaped, and fractionated void) by FI and compared lag time.
Results:
The overall distribution chart demonstrated that FI was the highest at lag time 0 second and decreased with the change in lag time both ways. The best fitting model for maximum FI and lag time was a cubic model (R2 = .282; P < .001). Children with lag times from 0 to less than 2 seconds showed the highest mean FI, while those with prolonged (>6 seconds) or delayed lag time (<-4 seconds) demonstrated lower mean FI values. EMG lag time of the tower-shaped curve was significantly close to 0 second, and plateau shaped and fractionated void had either prolonged or delayed.
Conclusions:
A lag time close to 0 second was associated with higher FI, representing hyperefficient voiding with a tower-shaped flow pattern. However, children with prolonged or delayed lag time showed a lower FI, implicating hypoefficient voiding and a plateau-shaped flow pattern. The relationship between FI and EMG lag time could be a cornerstone for a comprehensive understanding of voiding status.
Related Concept Videos
01:19Urodynamic Studies: Uroflowmetry
01:22Eulerian and Lagrangian Flow Descriptions
The Eulerian method focuses on fixed points in space where fluid properties, such as velocity, pressure, and temperature, are observed as the fluid moves between these...