Effect of 2-Hz Electroacupuncture Stimulation on Respiratory Function: A Randomized Controlled Trial

Abstract

Objective: The autonomic nervous system is involved in the regulation of airway smooth muscle. This study examined the effect of acupuncture stimulation in the vicinity of the cervical-sympathetic ganglion on respiratory function in humans. Materials and Methods: Twenty-four healthy adults (19 males and 5 females) were randomly assigned to a no-treatment group, a leave-needle group, and an electroacupuncture (EA) group in a crossover trial. In all groups, respiratory function was initially tested. In both acupuncture groups, after 5 minutes of rest, a 5-minute acupuncture stimulus was delivered, followed by 5 minutes of rest. Thereafter, respiratory function was again tested in all groups. Acupuncture was delivered in the vicinity of the cervical ganglia at the height of the sixth cervical vertebra on the left side and the vertebral artery node; the EA stimulus was set to 2 Hz, and the stimulation intensity was set to a level at which no pain was felt by the participants. Results: The EA group had significant increases in peak expiratory flow (PEF) and vital capacity (VC) after the intervention, compared to before intervention. Additionally, the EA group had significant increases in these parameters, compared to the no-treatment group. Conclusions: These results indicated that stimulation with 2-Hz EA in the vicinity of the cervical-sympathetic trunk causes an increase in PEF and VC, and increased bronchial dilation.

Keywords: airway smooth muscle; cervical-sympathetic ganglion; respiratory function test.

FIG. 1.

Research protocol. Initially, each participant was allowed to rest for 10 minutes in a sitting position. Then, respiratory function was measured, after which the participant was allowed to rest for 5 minutes in the supine position. Thereafter, a crossover test was conducted, in which no stimulation, needle-acupuncture stimulation, or 2-Hz EA stimulation was performed for 5 minutes. Respiratory function was measured after resting for 5 minutes after completion of the intervention. The washout period was set as 2 weeks. Measurement points: Before: Measure respiratory function in a sitting position, after 10 minutes of rest. After: After 5 minutes of rest in the supine position, perform 5 minutes of intervention, and 5 minutes of rest, after which the respiratory function is again measured. min, minutes; EA, electroacupuncture.

FIG. 2.

Changes in peak expiratory flow (PEF). Changes in PEF are shown for the [ × ] untreated group, [▴] leave-needle group, and [•] 2-Hz EA group. On the vertical axis, Before indicates the reference value as 0, and After indicates the amount of change in PEF between groups after intervention. On the abscissa, Before shows the reference value as 0, and After shows the change in each group after intervention. On the vertical axis, there was no significant difference in the [ × ] untreated group and [▴] leave-needle group from before to after the intervention. However, in the [•] 2-Hz EA group PEF was significantly different after the intervention, compared to before the intervention (P = 0.016). On the horizontal axis, there was no significant difference between the [ × ] untreated group and [▴] leave-needle group. There was a significant difference between the [•] 2-Hz EA group and the [ × ] untreated group after intervention (P = 0.033). Statistical analysis was performed by a 2-way analysis of variance and the significance level was set to P < 0.05. EA, electroacupuncture.

FIG. 3.

Changes in forced vital capacity (FVC). Changes in FVC are shown for the [ × ] untreated group, [▴] leave-needle group, and [•] 2-Hz EA group. On the vertical axis, Before indicates the reference value as 0, and After indicates the amount of change in FVC between groups after intervention. On the abscissa, Before shows the reference value as 0, and After shows the change in each group after intervention. On the vertical axis, there was no significant difference in the [ × ] untreated group, [▴] leave-needle group, and [•] 2-Hz EA group after intervention as compared to before intervention. On the horizontal axis, there was also no significant difference between any of the groups. Statistical analysis was performed by 2-way analysis of variance and the significance level was set to P < 0.05. EA, electroacupuncture.

Fig 4.

Changes in forced expiratory volume in 1 second (FEV 1.0). Changes in FEV 1.0 are shown for the [ × ] untreated group, [▴] leave-needle group, and [•] 2-Hz EA group. On the vertical axis, Before indicates the reference value as 0, and After indicates the amount of change in FEV 1.0 between groups after intervention. On the abscissa, Before shows the reference value as 0, and After shows the change in each group after intervention. On the vertical axis, there was no significant difference in the [ × ] untreated group, [▴] leave-needle group, and [•] 2-Hz EA group after intervention as compared to before intervention. In the horizontal axis, there was also no significant difference between any of the groups. Statistical analysis was performed by 2-way analysis of variance and the significance level was set to P < 0.05. EA, electroacupuncture.

FIG. 5.

Change in vital capacity (VC). Changes in VC are shown for the [ × ] untreated group, [▴] leave-needle group, and [•] 2-Hz EA group. On the vertical axis, Before indicates the reference value as 0, and After indicates the amount of change in VC between groups after intervention. On the abscissa, Before shows the reference value as 0, and After shows the change in each group after intervention. On the vertical axis, there was no significant difference in the [ × ] untreated group or [▴] leave-needle group after the intervention, compared to before the intervention. The [•] 2-Hz EA group showed a significant difference after the intervention as compared to before the intervention (P = 0.01). On the horizontal axis, there was no significant difference between the [ × ] untreated group and [▴] leave-needle group. The [•] 2-Hz EA group differed significantly from the [ × ] untreated group after the intervention (P = 0.018). Statistical analysis was performed by 2-way analysis of variance and the significance level was set to P < 0.05. EA, electroacupuncture. Due to the crossover test, the subjects had an age of 21.12 ± 1.42 years and a BMI of 22.39 ± 2.91 in all three groups. The respiratory function test is the actual value before and after stimulation, and the value after stimulation minus before stimulation.