Characterization of autonomic dysfunction in patients with irritable bowel syndrome using fingertip blood flow

Abstract

Fingertip blood flow (FTBF) as measured by laser Doppler flowmetry (LDF) measurement is considered an indicator of sympathetic nerve function. We evaluated autonomic function in patients with irritable bowel syndrome (IBS) by assessing FTBF with both LDF and continuous-wave (cw) Doppler sonography. Firstly, the two methods were compared in 40 healthy volunteers. Next, 59 patients with IBS as well as 118 healthy volunteer controls were studied. In the supine position, FTBF in the right index finger was measured with cw Doppler sonography, whereas FTBF in the left index finger was assessed with LDF. After baseline measurement for at least 5 min, the volunteers received sympathetic stimulation from cold stress applied without notification in the form of an icebag (0 degrees C) upon the left forearm for 1 min. The new cw Doppler sonography method can be used in place of the old LDF method for clinical purposes. FTBF velocity before stimulation (V(pre)) was significantly lower in the IBS group than that in the healthy volunteers (P < 0.01). In addition, the time required for FTBF to return to V(pre) after stimulation was significantly longer in the IBS group than that in the control group. (P = 0.02). Thus, measurement of FTBF with cw Doppler sonography can be useful in the assessment of sympathetic nerve function. The IBS patients showed an abnormal FTBF response suggesting the presence of excess sympathetic activity.