Two Devices for Reflex Voiding Following Spinal Cord Injury

Catheters are often used by individuals emptying their bladder following spinal cord injury. Reflex voiding is one of the bladder emptying methods, and it relies on spontaneous bladder contractions for voiding. These contractions occur with normal bladder filling or can be induced with suprapubic tapping and hair pulling. Poor voiding responses with reflex voiding can occur because of unwanted contractions of the urethra during bladder contractions and/or unsustained bladder contractions that result in high residual urine. The focus of this investigation is methods to reduce the high urethral resistance and to induce more sustained bladder contractions.

Obj.1. Measure pelvic floor contractile activity including the pelvic floor relaxation response (urethral and anal pressures, and EMG and the bulbocavernosus reflex) during dilation of the anus with digits or a balloon for 60 sec at diameters of 2, 3.5 and 5 cm.

Obj. 2. Measure urodynamic parameters (urethral and anal pressures, EMG, urine flow rates and bladder pressure) and compare three somatic methods of inducing bladder contractions, which are vibration (3 mm conducted at 100 strokes per second) at suprapubic and perineum (between the scrotum and anus) locations and tapping/suprapubic hair pulling. Conduct procedures using 80% of cystometric capacity and define a responder to any of the three interventions as an increase of 10 cm H20 pressure or greater. For nonresponders go to objective 4.

Obj. 3. For responders to Ob. 2, further evaluate effects of perineum vibration by conducting comparisons with (1) anal dilation to no dilation; (2) A vibration stroke length of 1.5 mm to 3 mm; (3) A bladder volume of 50% cystometric capacity to 80%.

Obj. 4. Compare the urodynamic responses to spontaneous bladder contractions induced by bladder filling (cystometry) with and without anal dilation.

Obj. 5. Conduct a human factors assessment. Determine problems with use of the current perineum vibration and anal dilation devices. Evaluate if curving the tip of the insertion device for the anal dilator would facilitate insertion and if the use of a plastic bag would improve hygiene. Discuss features important for a user-friendly home-use device.

Design \& Methods: All objectives will be conducted during a single, urodynamic, testing protocol. Fifteen male SCI patients with upper-motor-neuron injuries will be enrolled. Urodynamic responses are our primary measure. These include urethral and anal sphincter pressures and anal surface EMG, bladder contractions including peak pressure and duration of pressure, voiding responses including peak voiding rate and duration of voiding. These measures will be evaluated during anal dilation and perineum vibration methods alone and in combination. Anal dilation protocols will include random and duplicated testing. Vibration methods will only be done once to limit the risk of autonomic dysreflexia. Analysis of variance followed by Student-Neuman-Keuls post hoc test will be conducted to assess significant differences.

Importance of Findings: Results from these studies will provide evidence for anal dilation to reduce DSD and perineum vibration to improve bladder contractions. Thus, these studies could provide important evidence for improved methods of RV for individuals with SCI. During this pilot study, subjects will not be counseled to conduct RV for their daily or regular bladder management program.