The safety cutoff storage pressure for preventing upper urinary tract damage in neurogenic bladder from spinal cord...

Low-compliance bladder or high bladder pressure undoubtedly leads to hydronephrosis and renal impairment. As four decades have elapsed since a previous study found a detrusor leak-point pressure (DLPP) >40 cm H₂ O to result in hydronephrosis, we suspected the possibility of hydronephrosis or vesicoureteral reflux occurring at any point below the 40 cm H₂ O DLPP reference. Therefore, this study aimed to determine the storage detrusor pressure value and risk factors related to upper urinary tract damage (UUTD).

This study retrospectively reviewed the hospital records of 110 patients who visited the Neurogenic Bladder TU Service of Excellence Unit, Thammasat University Hospital, Pathum Thani, Thailand, and were diagnosed with neurogenic bladder between 2016 and 2020. The inclusion criteria were as follows: patients who were diagnosed with neurogenic bladder from spinal cord problems (spinal dysraphism, spinal cord disease [tumor, degenerative, arteriovenous malformation, etc.], or traumatic spinal cord injury) and underwent a complete examination, including urodynamic study and renal ultrasound. The exclusion criteria were as follows: patients who had previous pelvic irradiation, other concomitant neurological disease (stroke, Parkinson's disease, etc.), or other urological diseases (stone, tumor, etc.), and those who had an indwelling suprapubic or urethral catheter. We identified the cutoff point for storage pressure related to UUTD using receiver operating characteristic (ROC) curve analysis to identify the value that produced maximum sensitivity and specificity. To identify risk factors for developing UUTD, we included seven risk factors: intravesical pressure, poor compliance, detrusor overactivity (DO), detrusor sphincter dyssynergia (DSD), level of the spinal cord pathology, male sex, and spontaneous voiding in univariable and multivariable regression analyses.

Of the 110 patients who met the inclusion criteria, 22 were excluded from the study. Fifty-nine patients had a normal upper urinary tract, and 29 had UUTD. The mean age, sex, voiding pattern, type of spinal cord pathology, and level of spinal cord lesions were not different between the two groups. After performing ROC curve analysis, a cutoff value for daily storage pressure ≥15 cm H₂ O provided 79.31% sensitivity and 67.80% specificity (area under the ROC curve: 0.73) for UUTD development. From univariable analysis, low compliance (cutoff values at <12.5 and <20 ml/cm H₂ O) and a storage pressure ≥15 cm H₂ O was related to UUTD with statistical significance (risk ratio [RR]: 3.16, 2.3, and 3.6, respectively [p < 0.05]). After performing multivariable analysis, a storage pressure ≥15 cm H₂ O and both cutoff values for low compliance were related to UUTD with statistical significance (RR: 3.9, 2.4, and 3.2, respectively [p < 0.05]). However, other factors, including male sex, spontaneous voiding, suprasacral lesion, DSD, and DO, were not related to UUTD.

Our results demonstrated that low compliance and a storage pressure ≥15 cm H₂ O were significantly associated with UUTD. Various bladder-management strategies have been developed to prevent UUTDs. However, the main concept continues to be the maintenance of a low storage pressure.