Acupuncture transcutaneous electrical nerve stimulation reduces discomfort associated with barostat-induced rectal distension:A randomized-controlled study

摘要

AIM:To explore the effectiveness of acupuncture transcutaneous electrical nerve stimulation(Acu-TENS), a non-invasive modality in reduction of rectal discomfort during barostat-induced rectal distension. METHODS:Forty healthy subjects were randomized to receive 45 min of either Acu-TENS or placebo-TENS(no electrical output)over acupuncture points Hegu(largeintestine 4),Neiguan(pericardium 6)and Zusanli(stomach 36).A balloon catheter attached to a dual-drive barostat machine was then inserted into the subjects'rectum.A step-wise(4 mmHg)increase in balloon pressure was induced until maximal tolerable or 48 mmHg.Visual analogue scale and a 5-point subjective discomfort scale(no perception,first per-ception of distension,urge to defecate,discomfort/ pain and extreme pain)were used to assess rectal discomfort at each distension pressure.Blood beta-endorphin levels were measured before,immediately after intervention,at 24 mmHg and at maximal toler- able distension pressure. RESULTS:There was no difference in the demographic data and baseline plasma beta-endorphin levels between the two groups.Perception threshold levels were higher in the Acu-TENS group when compared to the placebo group,but the difference reached statistical significance only at the sensations"urge to defecate"and"pain".The distension pressures recorded at the"urge to defecate"sensation for the Acu-TENS and placebo-TENS groups were 28.0±4.5 mmHg and 24.6±5.7 mmHg,respectively(P=0.043);and the pressures recorded for the"pain"sensation for these two groups were 36.0±4.2 mmHg and 30.5± 4.3 mmHg respectively(P=0.002).Compared to the placebo group,a higher number of participants in the Acu-TENS group tolerated higher distension pressures (>40 mmHg)(65%in Acu-TENS vs 25%in placebo, P=0.02).The plasma beta-endorphin levels of the Acu-TENS group were significantly higher than that of the placebo group at barostat inflation pressure of 24 mmHg(1.31±0.40 ng/mL vs 1.04±0.43 ng/mL,P= 0.044)and at maximal inflation pressure(1.46±0.53 ng/mL vs 0.95±0.38 ng/mL,P=0.003). CONCLUSION:Acu-TENS reduced rectal discomfort during barostat-induced rectal distension and concur-rently associated with a rise in beta-endorphin level.