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What volume can a child normally store in the bladder at a safe pressure?

A M Houle1, R F Gilmour, B M Churchill

  • 1Department of Surgery (Division of Urology), Hospital for Sick Children, Toronto, Ontario, Canada.

Insights

Children can store 98.1% of their total bladder capacity at pressures below 20 cm. water, crucial for understanding normal pediatric bladder function and storage. This finding aids in assessing bladder health in children.

Area of Science:

  • Pediatric Urology
  • Urodynamics
  • Pediatric Nephrology

Background:

  • Assessing normal bladder volume storage at safe pressures is vital for pediatric urological health.
  • Previous studies lacked comprehensive data on bladder storage capacity relative to pressure in children.

Purpose of the Study:

  • To establish normal bladder storage volumes at safe detrusor pressures in children.
  • To propose criteria for evaluating bladder storage characteristics in pediatric patients.

Main Methods:

  • Reviewed 923 pediatric urodynamic studies, focusing on 69 normal examinations in children (17 boys, 52 girls).
  • Performed continuous intermediate flow water cystometrograms to measure total bladder capacity, resting pressures, and volume stored at specific detrusor pressures.
  • Calculated patient ages and body surface areas to analyze storage capacity independently of these factors.

Main Results:

  • Over 95% of children could store 98.1% of their total bladder capacity at detrusor pressures < 20 cm. water.
  • 99.9% of total bladder capacity was storable at detrusor pressures < 30 cm. water, irrespective of age or body surface area.
  • A formula for minimal acceptable total bladder capacity was derived: 16(age) + 70 ml.

Conclusions:

  • Children can safely store a significant majority of their bladder volume at low detrusor pressures.
  • The findings provide objective criteria for assessing normal bladder storage function in pediatric urodynamics.
  • Established parameters can aid in diagnosing and managing conditions affecting bladder storage in children.

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