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[Urodynamic investigations. Volume/flow and pressure/flow relationship in children (author's transl)]
Insights
Urodynamic investigations using uroflowmetry and cystometry in children revealed that catheter use alters urinary flow measurements. Pressure/flow diagrams effectively differentiate normal and abnormal bladder outlet function.
Area of Science:
- Pediatric Urology
- Urodynamics
- Medical Device Engineering
Context:
- Urodynamic investigations are crucial for assessing lower urinary tract function in children.
- Subvesical outflow disturbances require accurate diagnostic methods for timely intervention.
- Standard urodynamic measurements can be influenced by the instrumentation used.
Purpose:
- To evaluate the impact of small urethral catheters on urodynamic measurements in children.
- To establish normal pressure/flow relationships for accurate diagnosis of bladder outlet obstruction.
- To differentiate and classify pathological voiding patterns using pressure/flow diagrams.
Summary:
- Urodynamic investigations, including uroflowmetry and cystometry with 1.5 mm catheters, were conducted on 290 children (122 normal, 168 with outflow disturbances).
- Catheterization significantly altered maximal urinary flow, showing decreased dependence on voiding volume, attributed to catheter-induced widening of the subvesical tract.
- Pressure/flow relations, analyzed using diagrams, demonstrated a consistent pattern similar to a rigid tube, enabling reliable differentiation between normal and pathological voiding.
Impact:
- The study provides validated normal ranges for pressure/flow relations, aiding in the diagnosis of pediatric lower urinary tract dysfunction.
- Uroflowmetry shows diagnostic value in boys, while pressure/flow diagrams are essential for recognizing subvesical obstruction in both sexes.
- This method allows for a more precise assessment of the functional obstructive effect and its compensation or decompensation status.
Abstract:
Subject of the report are urodynamic investigations in 122 children with a normal urinary tract and in 168 children with disturbances of the subvesical outflow. The children were divided into four groups corresponding to age and sex. Measuring methods were uroflowmetry and cystometry. The latter was performed with small urethral plastic catheters 1,5 mm in diameter. In comparison with the investigations without catheter our measured values show a revoked or distinctly decreased dependence of the maximal urinary flow on the micturition volume. This behaviour can be explained by an approximately maximal widening of the subvesical outflow tract due to the obstructive effect of the catheter. The pressure/flow relations confirm this behaviour. They correspond to those of a rigid tube with individual constant diameter. This condition permits a good comparison between the measured values and an accurate separation between normal and pathologic cases. Normal ranges of the pressure/flow relations at the moment of maximal flow were calculated and presented by diagrams. Pathologic micturitions can be differentiated and classified by such diagrams. Among the various urodynamic methods the uroflowmetry has a good diagnostic value in boys. With the urethra resistance relation PQmax/Qmax2 a subvesical obstruction may be recognized in both sexes. A better assessment of the functional obstructive effect with regard to compensation and decompensation is only possible with the demonstrated pressure/flow diagrams.