Figure 1: A composite graph of UDS data with NIRS parameters total hemoglobin (tHb) deoxygenated hemoglobin (HHb) and oxygenated hemoglobin (O2Hb) and EMG in a 64-year-old man. He had a 5-year history of increasing obstructive LUTS, had failed medical therapy, and complained of difficulty initiating urination, a weak stream, and slow flow. As Pdet increases prior to uroflow, there is a decrease in O2Hb reflected by a fall in tHb and HHb begins to rise. During uroflow, this positive trend in HHb increases, some rise in O2Hb is evident following Qmax but the associated rise in tHb predominantly reflects a greater rise in HHb concentration. This implies an imbalance in oxygen supply and demand during voiding.