Establishing initial resting abdominal pressure in children undergoing urodynamics

Introduction: The International Continence Society recommends zeroing of transducers to the atmospheric pressure for invasive urodynamics. The range of abdominal pressure relative to atmospheric pressure is well-known in adults but has not been described in children. This prospective observational study was carried out to establish baseline abdominal in children.Materials and Methods: Prospective, multicenter, observational study of 100 children aged 0-18 years undergoing invasive urodynamics using water-filled systems. Initial resting abdominal pressure, intravesical pressure and detrusor pressure were recorded in supine, sitting, and standing position (as age- and diagnosis-appropriate). This data was analyzed using SPSS 20.0.0 with regard to age, gender, height, weight, body mass index, and underlying diagnosis (classified as neurogenic or non-neurogenic). Nonparametric tests were used (2-sided p < 0.05, significant).Results: Initial resting abdominal pressure (inter-quartile range) in children was between 5 and 15 cmH(2)O in the supine, 13-20 cmH(2)O in the sitting, and 15-21 cmH(2)O in the standing position. These pressures were not consistently influenced by age, gender, height, weight or underlying diagnosis. The initial resting detrusor pressure was noted to be 0-4 cmH(2)O without any difference based on posture. Limitations include use of two-tube technique, relatively small number of subjects across each age group, wide range of underlying diagnoses and need for manual smoothing of some traces.Conclusion: This study defines initial resting abdominal pressure at urodynamics in children and notes that, as with adults, it is possible to define widely applicable ranges regardless of individual characteristics. These pressures appear lower than those noted historically in adults.