Detrusor overactivity (DO) is characterized by involuntary bladder contractions that may cause overactive bladder (OAB) symptoms, such as urination and incontinence. While Urodynamics (UDS) is the established gold standard test for diagnosis of DO, Near-infrared spectroscopy (NIRS) measures tissue hemodynamics non-invasively, offering a potential cost-effective imaging alternative to UDS. This study evaluates bladder NIRS as a potential non-invasive alternative for detecting DO in individuals with OAB.
OAB patients participated in simultaneous bladder NIRS and UDS studies. Peak and area-under-the-curve (AUC) values were calculated during DO events using detrusor pressure (pDet) and bladder NIRS (oxygenated hemoglobin (O2Hb)). NIRS segments during DO events were compared within subjects to control segments without DO (internal control), and externally to segments from participants without DO (external control). To account for data drift, a normalized AUC for NIRS data over the testing period was computed after motion artifact correction and subtraction of the area under a linear fit.
Among 44 enrolled female OAB participants, four experienced demonstratable DO, producing a total of 39 DO events. During DO events, pDet peaks were significantly higher (51.8 ± 7.3 cm H2O) compared to internal (3.7 ± 0.5 cm H2O), and external control periods (5.4 ± 1.2 cm H2O) (p0.001). Likewise, NIRS O2Hb peaks were higher during DO events (p0.001). pDet AUC was 30,988 ± 7,318.2 (DO), 444.5 ± 86.7 (internal control), and 1,036.6 ± 352.9 (external control), with similar outcomes seen with NIRS O2Hb (p0.001). Normalized NIRS AUC was greater in patients with DO (0.56 ± 0.11) than in external controls (0.09 ± 0.01, p0.001). Using a threshold AUC value of 0.146, provides clear separation between urodynamic segments with and without DO, p0.05 (Figure 1).
DO events were consistently associated with marked increases in both pDet and NIRS O2Hb values when compared to control segments. These findings support the potential use of bladder NIRS as a non-invasive tool for detecting DO in OAB patients.
K12HD108269, Virginia Commonwealth University (VCU) School of Medicine Summer Research Fellowship Program, R21DK128649
