Estimating postvoid residual volume without measuring residual bladder volume during serial cystometrograms.
The postvoid residual volume (PVR) is a common urodynamic parameter used to quantify the severity of lower urinary tract dysfunction. However, the serial cystometrograms that are typically used to assess bladder function in animal models make measuring PVR very difficult. Current approaches are to either remove PVR after each void to measure it, which is disruptive to the bladder, or to neglect the unknown contribution to PVR from ureter flow, which results in inaccurate estimates. We propose a procedure to estimate PVR during a serial cystometrogram that requires only a single measurement, rather than measuring after each void. Moreover, this measurement can occur at the end of the experiment such that it does not affect the bladder during data collection. We mathematically express PVR for all voids during a serial cystometrogram using a linear recurrence equation and use this equation to build an estimation procedure for PVR. Using in vivo measurements in urethane anesthetized rats and computer simulations we show that the estimation procedure is at least as accurate in determining PVR as the traditional method of measuring PVR after each void. Furthermore, we demonstrate the adverse effects of repeated PVR measurements in a common animal model of cystitis. Using the proposed procedure can increase the efficiency and accuracy of determining PVR for a serial cystometrogram and is less disruptive to the system under study. This, in turn, allows the calculation of other urodynamic parameters that are critical for research studies, including voiding efficiency and bladder capacity.
Department of Biomedical Engineering, Duke University, Durham, North Carolina; zd10@duke.edu.
Zachary C
0000-0003-1474-1259
ZC
Danziger
Department of Biomedical Engineering, Duke University, Durham, North Carolina; Department of Neurobiology, Duke University, Durham, North Carolina; Department of Surgery, Duke University, Durham, North Carolina; and Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina.
Warren M
WM
Grill
D019342:Acetic Acid; D000465:Algorithms; D000818:Animals; D003198:Computer Simulation; D003556:Cystitis / Q000139:chemically induced / Q000473:pathology; D005260:Female; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D014513:Ureter / Q000502:physiology / Q000503:physiopathology; D001743:Urinary Bladder / Q000033:anatomy & histology*; D014554:Urination; D014563:Urodynamics
D019342:Acetic Acid
rat; recurrence equation; underactive bladder; ureter; urodynamics; voiding efficiency