Near-infrared spectroscopy of the detrusor during urodynamics with simultaneous ultrasound measurements of bladder dimensions and position

Near Infrared Spectroscopy (NIRS) has recently been applied to evaluation of bladder function during voiding by transcutaneously monitoring changes in the concentration of oxygenated (O₂Hb) and de-oxygenated (HHb) haemoglobin within the detrusor muscle during voiding. This prospective cohort study evaluated the consistency of bladder anatomy relative to the suprapubic location of the NIRS sensor patch during simultaneous invasive urodynamic pressure flow studies (UDS) and non-invasive NIRS monitoring in female subjects evaluated for lower urinary tract symptoms (LUTS). Pelvic ultrasound measurements of the bladder were performed after bladder emptying, at 150 ml, 300 ml and maximum capacity in supine, sitting and upright positions; simultaneous NIRS data at 10 Hz were collected during UDS. Ultrasound measurements in 24 subjects (14 with and 14 without hysterectomy) showed that a NIRS sensor patch positioned on the abdomen 2 cm superior to the symphysis remained directly over the anterior wall of the bladder throughout the voiding cycle, with no significant difference in bladder measurements relative to the abdominal wall with or without hysterectomy. At higher bladder volumes the majority of bladder expansion appeared to involve the dome.

Conclusions: With bladder volumes of 150 cc or greater the anterior wall is within the field of view of a NIRS sensor on the abdominal skin, and prior hysterectomy does not compromise NIRS monitoring of the detrusor.