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Voiding Pressures in Boys: Pdetmax versus PdetQmax - Does it Make a Difference?
Poonam Guha Vaze1, Subhasis Saha1, Rajiv Sinha2
1Department of Pediatric Surgery, AMRI Hospitals, Kolkata, West Bengal, India.
Insights
Voiding pressure measurements in boys using urodynamics (UDS) are more reliable with PdetQmax, an age-independent parameter, compared to Pdetmax. This finding could improve the diagnosis of pediatric voiding dysfunctions.
Area of Science:
- Pediatric Urology
- Urodynamics
- Lower Urinary Tract Symptoms
Background:
- Invasive urodynamics (UDS) is standard for pediatric voiding investigations.
- Current pediatric voiding pressure studies lack standardized nomenclature and yield heterogeneous results, limiting reliability.
- Adult urodynamics has established nomograms, unlike pediatric studies.
Purpose of the Study:
- To investigate voiding parameters during UDS in boys.
- To compare Pdetmax and PdetQmax values in pediatric patients.
Main Methods:
- Retrospective review of invasive UDS data from 106 neurologically normal boys (6 months-16 years).
- Analysis of detrusor pressure at maximum flow (PdetQmax) and maximum detrusor pressure (Pdetmax).
- Comparison of observed values with existing pediatric urodynamics literature.
Main Results:
- Pdetmax decreased with age, while PdetQmax remained age-independent.
- The difference between Pdetmax and PdetQmax was greater in younger children.
- Observed Pdetmax values aligned with heterogeneous literature, but PdetQmax values were significantly lower.
Conclusions:
- Pediatric voiding pressure studies are often unreliable due to heterogeneous Pdetmax values.
- PdetQmax is age-independent and significantly lower than Pdetmax.
- Utilizing PdetQmax may enhance the reproducibility and diagnostic value of pediatric urodynamics.
Introduction:
Invasive urodynamics (UDS) is a standard investigation in children. Studies measuring voiding pressures in children use varied nomenclatures and quote a wide range of voiding pressures. Thus, voiding pressures in children are not considered reliable and they do not find any place in the pediatric diagnostic armamentarium. On the contrary, adult studies have well-defined nomograms and standard values which make voiding studies indispensable in the diagnosis of voiding dysfunctions in adults. The difference primarily lies in the uniformity of parameters assessed in adults and the contrasting heterogeneity in the pediatric literature.
Objective:
The objective of this study was to study the voiding parameters observed during UDS in boys.
Study Design:
We retrospectively reviewed the pressure flow data obtained during conventional invasive UDS in 106 neurologically normal boys (6 months-16 years) who had different indications for urodynamics. The values of Pdetmax and PdetQmax were analyzed and compared with the existing data of pressure flow studies in children.
Results:
Pdetmax decreased with age whereas PdetQmax was independent of age. The difference between the values of Pdetmax and PdetQmax was more in the younger kids. The wide range of voiding detrusor pressure (Pdet) in the existing pediatric literature is similar to the values of Pdetmax observed in our study, whereas the value of PdetQmax is much lower.
Discussion:
The values of Pdetmax observed in this study are similar to the values of "maximum Pdet during voiding" documented in previous studies and are determined by detrusor contractility and functional/dynamic contraction of outflow during voiding. PdetQmax has been documented in very few pediatric studies and is significantly less than Pdetmax. Further prospective studies are needed to corroborate UDS findings with radiologic/cystoscopic findings to create nomograms of voiding parameters in children.
Conclusion:
Existing literature on pediatric voiding studies mentions voiding pressures during variable phases of void (usually Pdetmax) and the values have been very heterogeneous, making voiding pressure-flow studies unreliable in children. PdetQmax values are much lower than values quoted as "standard" pressures and are age independent. The use of PdetQmax instead of PdetMax may make voiding pressures in children more reproducible and informative.
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