Aim

To compare the difference of remote effects of acupuncture between metal needle and laser needle on facial blood perfusion (FBP).

Methods

Hand acupuncture and laser-needle acupuncture were randomly used on Hegu (LI4) in 20 healthy volunteers. FBP was observed by speckle contrast imager before, during, and after the acupunctures.

Results

For hand acupuncture there were gradual increases on the nose and left and right visor areas (p < 0.05 or p < 0.01) during the acupuncture and on an immediate increase (p < 0.01) that remained constant during the acupuncture on the forehead area but no significant increase on mouth area. During laser-needle acupuncture, on the other hand, there was a tendency of increase on the nose, left visor, and right visor areas but these were non significant.

Conclusion

Hand acupuncture can influence FBP in remote places connected by meridians.

Treating facial symptoms by acupuncturing Hegu (LI4) is a rule in acupuncture clinic. In 1989, Zhang et al. [1] examined the rule by infrared imager and found an increase of temperature on the face when needling Hegu while no obvious changes when needling arm or Waiguan (TE5) [1]. Li et al. [2] observed the temperature on different areas on the face and found a striking influence on mouth and nose during needling Hegu [2]. In 2010, Song [3] compared the changes in temperature on the face when needling Hegu or Guangming (G37) by infrared imager and found a marked increase on visor and mouth when needling Hegu. To study the connection between Hegu and the face, Chen et al. [4] found neural fibers projecting to solitary nucleus directly and indirectly from both areas, which may be a morphological basis of such connection.

The laser needle is a recently developed acupuncture tool that has the advantage of being mostly painless and is often preferred, by Western patients in particular. To study the mechanism of the laser needle, Litscher et al. [5] observed the influence of blood flow velocity in cerebral arteries by multidirectional transcranial ultrasound Doppler sonography (TCD). When giving laser stimulation on seven acupoints related to vision, they found that an increasing velocity in the ophthalmic artery but no significant change in the middle cerebral artery, but noted a more striking increase by metal needle on the same acupoints [5].

Skin blood perfusion is an important index in studying peripheral effects of acupuncture. Using laser Doppler perfusion imager (LDPI) in 2008, Zhang et al. [6] found three effects of acupuncture when needling Hegu such as local effect, holistic effect, and effect along meridians. Apart from laser Doppler method, a more recent technique called laser speckle technique was developed that can capture blood perfusion image in real time and has a superior resolution. With this new technique, we observed the facial blood perfusion (FBP) during hand acupuncture and laser-needle acupuncture to assess whether there is any difference between these two therapies on this parameter.

2.1. Equipment

2.1.1. Laser needle and metal needle

A laser-needle instrument (LASERneedle, Germany) with wavelength 685 nm and output power 50 mW and a 0.30 × 40-mm metal needle (Huacheng, China) were used for acupuncture.

2.1.2. Laser speckle technique on blood perfusion imaging

FBP was captured by a new instrument called Full-Field Laser Perfusion Imager (MoorFLPI, UK) in which the principle of speckle image was used. The technique, known as laser speckle contrast image, exploits the phenomenon that the random speckle pattern generated when tissue is illuminated by laser light changes when blood cells move within the region of interest. When there is a high level of movement (fast flow) the changing pattern becomes more blurred and the contrast in that region reduces accordingly. The spatial resolution is 49,000 pixels/cm² and temporal resolution rate ≤25 frames/second. The imager can give two images simultaneously: blood perfusion and photographic image of an interested region. Data are input into a computer through an A/D transfer card and analyzed by MoorVer2.0 software.

MoorFLPI was set on high resolution, 100-frame/seconds temporal filter, 25-Hz collecting rate, and exposal time 8.3 ms. Five images were continuously obtained with 4-second intervals per measurement. Therefore, each measurement lasted 20 seconds.

2.2. Subjects and environment

The experiment was carried out in 20 healthy volunteers (M/F, 8/12) with an average age 33.5 ± 9.7 years. The volunteers were randomly selected to do hand acupuncture or laser-needle acupuncture first then the other acupuncture on a different day. The room temperature was kept at 26 ± 1°C; no strong sunlight entered and no infrared light source was in the room. The experiment was approved by the ethics committee of the China Academy of Chinese Medical Science.

2.3. Experimental procedures

The camera was placed 40–45 cm from volunteers’ faces (Fig. 1) and suitably focused and zoomed. Before collecting images, subjects were asked to rest for approximately 10 min to adjust to the room temperature. Metal needle or laser needle was selected and stimulation given on Hegu on the right side. Before the stimulation, one measurement was done with five photographs continuously. Then, stimulation was given and measurements were repeated at 0, 5, 10, and 15 min during the stimulation. After 20 min of stimulation, the needle was removed and three further measurements were performed at 0, 5, and 10 min after the stimulation (Fig. 2). Hand acupuncture was given by an experienced acupuncturist until the subject felt “Deqi” while the laser-needle was applied.

Figure 1. Measuring facial blood perfusion (FBP) by MoorFLPI imager.

Figure 2. Experimental procedure.

The whole measured face was divided into five subareas such as mouth, nose, left visor, right visor, and forehead area (Fig. 3). The mean values in each area were calculated first among five photographs in eight periods then were averaged through the 20 cases.

Figure 3. Subareas on the face: 1, mouth area; 2, nose area; 3, left visor area; 4, right visor area; and 5, forehead area. Left picture, blood perfusion; right picture, photograph.

2.4. Statistical analysis

Paired t-test was used to compare the difference between the blood flow per unit (PU), the unit of measurement as defined by the instrument manufacturer, in different periods of acupuncture with p < 0.05 denoted as significant.

The results of hand acupuncture are shown in Table 1 and Fig. 4 and of laser-needle acupuncture in Fig. 5.

*P < 0.05 vs. before acupuncture; **p < 0.01 vs. before acupuncture..

&md=tbl&idx=1' data-target="#file-modal"">Table 1

The changes of FBP on five areas of face in the different periods when giving hand acupuncture and laser-needle acupuncture (Means ± SD, PU).

Period	Mouth area	Nose area	Left visor area	Right visor area	Forehead area
Before hand acup.	499.1 ± 179.2	302.9 ± 93.9	253.3 ± 70.4	265.0 ± 79.3	169.4 ± 60.5
0 min acup.	496.7 ± 148.4	303.4 ± 80.6	291.5 ± 83.5**	295.3 ± 78.5**	180.3 ± 62.1*
5 min acup.	496.4 ± 143.5	319.1 ± 76.2	275.4 ± 86.8*	280.1 ± 88.9	182.8 ± 65.7**
10 min acup.	474.8 ± 155.2	321.6 ± 76.3	286.4 ± 96.6*	294.7 ± 110.1*	181.9 ± 65.5**
15 min acup.	488.0 ± 144.8	333.6 ± 82.0*	301.4 ± 115.7*	309.2 ± 113.9*	187.8 ± 68.1**
Stop acup.	521.9 ± 137.4	348.8 ± 79.6**	325.0 ± 128.3**	342.3 ± 113.8**	189.3 ± 71.6**
Stop 5 min	499.9 ± 167.6	343.4 ± 86.3**	324.1 ± 142.6**	326.9 ± 117.0**	189.5 ± 72.7**
Stop 10 min	503.6 ± 154.1	341.6 ± 92.1*	325.4 ± 145.5*	324.5 ± 115.9**	186.0 ± 74.3*
Before laser-needle acup.	447.6 ± 160.3	317.1 ± 81.5	279.0 ± 76.3	297.6 ± 81.1	186.8 ± 53.6
0 min acup.	438.4 ± 151.6	302.9 ± 76.6	291.6 ± 98.2	283.6 ± 73.4	184.7 ± 59.7
5 min acup.	443.0 ± 118.5	306.5 ± 74.3	264.1 ± 66.5	276.9 ± 87.3	181.3 ± 54.3
10 min acup.	431.5 ± 130.0	322.2 ± 91.7	279.3 ± 74.5	287.7 ± 91.8	187.6 ± 63.2
15 min acup.	471.2 ± 137.3	324.0 ± 83.2	285.1 ± 85.9	305.5 ± 101.3	186.5 ± 60.3
Stop acup.	433.3 ± 156.0	323.2 ± 81.3	281.4 ± 71.3	304.1 ± 93.6	183.8 ± 58.4
Stop 5 min	465.7 ± 147.9	335.4 ± 88.5	294.3 ± 83.5	318.9 ± 100.0	190.8 ± 60.7
Stop 10 min	451.6 ± 132.3	338.4 ± 87.0	301.0 ± 99.0	327.0 ± 116.4	189.4 ± 62.5

*P < 0.05 vs. before acupuncture; **p < 0.01 vs. before acupuncture..

Figure 4. Changes in FBP in five facial areas when giving hand acupuncture. Nos. 1–8 represent FBP before, 0, 5, 10, and 15 min during, and 0, 5, and 10 min after stopping the acupuncture.

Figure 5. Changes in FBP in five facial areas when giving laser-needle acupuncture. Nos. 1–8 represent FBP before, 0, 5, 10, and 15 min during, and 0, 5, and 10 min after stopping the acupuncture.

Table 1 Changes in FBP in five areas of the face in different periods when giving hand acupuncture (mean ± SD). *p < 0.05 vs. before acupuncture; **p < 0.01 vs. before acupuncture.

Comparison of FBP during and after versus before acupuncture by paired t-test revealed that for hand acupuncture there was no significant in mouth area whereas in nose area there was a gradual increase that reached significance at 15 min during the acupuncture. For both left and right visors FBP immediately increased significantly during acupuncture, slightly decreased at 5 min then continuously increased at 10 and 15 min as well as immediately after withdrawing the needle. There was a stop of increase or slight decrease after withdrawing the needle on the nose, left visor, and right visor. Differences between the decrease of FBP in left visor and right visor at the time of withdrawing the needle and at 5 and 10 min after stopping the acupuncture are shown in Table 2.

*Compared between left visor and right visor p < 0.05..

&md=tbl&idx=2' data-target="#file-modal"">Table 2

Decreases of FBP after stopping acupuncture (mean ± SD).

	5 min	10 min
Left visor	0.96 ± 37.5	−0.38 ± 44.7
Right visor	15.4 ± 25.6	17.8 ± 36.5*

*Compared between left visor and right visor p < 0.05..

Decreases were significantly different at 10 min between left visor and right visor, suggesting a more striking decrease on right visor on the ipsilateral side of acupuncturing point. For the forehead area, an immediate increase of FBP was noted and remained constant thereafter.

Under laser-needle acupuncture although FBP exhibited a tendency to increase continuously even after turning off the laser, it did not reach significance in all five areas (p > 0.05).

Comparison of FBP before acupuncture in five facial areas, i.e., the natural distribution, revealed that this parameter was highest in mouth area then nose area, similar FBP between left visor and right visor, and lowest on the forehead. Significant differences between the mouth, nose, visor, and forehead were detected by paired t-test (p < 0.01).

Because the forehead is thought to have no relation with the large intestine meridian, it was regarded as a reference point. The changes on the two visors were subtracted from those on the forehead to obtain the pure changes (Table 3); zero assumption was used to test the significance.

Table 3

Pure changes in FBP on left visor and right visor (means ± SD).

	During acupuncture				After acupuncture
	0 min	5 min	10 min	15 min	0 min	5 min	10 min
Left visor	27.4 ± 47.2*	8.8 ± 36.5	20.6 ± 50.2	29.9 ± 72.1	51.9 ± 97.1*	50.7 ± 102.2*	55.6 ± 112.3*
Right visor	19.5 ± 43.5	1.9 ± 36.8	17.2 ± 45.5	25.9 ± 64.4	57.4 ± 64.9**	41.9 ± 69.3*	43.0 ± 70.6*

The newest laser speckle image technique was used in the experiment to measure FBP. Because the source is near infrared the instrument is classified as a class 1 laser, which is safe for eyes; therefore, the subjects do not need to wear protective glasses, allowing ease of measuring FBP. In addition, because subjects often blink and disturb the measurement, which is highly sensitive to movement, the area of the eyes was not considered. An advantage of this technique is that it allows simultaneous measurement of the whole field, which is not usually possible when using a single-beam laser source.

When stimulating the Hegu point by a metal needle, FBP increased on almost all the facial areas except the mouth, among which most obvious continuous increases were noted on left and right visor areas and a slight decrease after withdrawing the needle, implying that the increase was indeed caused by the acupuncture. FBP at the nose increased slowly compared with visor, suggesting that the signal through large intestine meridian arrived first at the visor area then the nose. FBP on the forehead increased at the beginning of needle acupuncture and remained constant during the whole process, implying a different pathway from visor and nose.

Hegu is the source point of the large intestine meridian; there is a clinic rule that facial symptoms are treated by acupuncturing Hegu. We found that FBP was highly influenced by acupuncturing Hegu. The large intestine meridian goes across the visor and ends at the side of the nose, and an obvious increase of FBP on visor and nose was found corresponding to this route. However, although mouth area relates with Hegu by the meridian, no significant increase was found. One possible reason for this observation may be a very high FBP before the acupuncture on mouth area, which caused a low increase by acupuncture. Also, the route of large intestine meridian does not pass directly across the mouth so that the influence may not be so obvious (Fig. 6).

Figure 6. Route of large intestine meridian. (From Outline of Chinese Acupuncture edited by Chen XN, 1979.)

Our results are different from Li’s finding that the temperature on mouth increased strikingly by acupuncturing Hegu [2]. However, these two experiments observed different parameters and temperature on the face is not necessarily correlated with FBP.

Although the large intestine meridian does not pass across forehead, an obvious increase of FBP in this area was observed at the beginning of hand acupuncture. On the other hand, it kept constant thereafter, implying that a fast holistic response happened on the forehead that is similar to the finding in our earlier study that regardless of stimulating acupoint or non-acupoint, there was a holistic increase in whole observed areas [6]. The mechanism of such response may due to neural–blood reflection, which is different from the slow increase on visor and nose where the signal may transfer through neural–liquid relay transmission as proposed by Zhang in 1999 [7]. This increase could be regarded as an overlapped rise on the holistic increase. Therefore, we analyzed the pure increase by calculating those on the other four areas minus that on the forehead. Significant (p < 0.05) increases were observed at 0 min during acupuncture and 0, 5, and 10 min after withdrawing the needle on left visor and 0, 5, and 10 min after withdrawing the needle on right visor. Our calculations confirmed the increases on two visors were not a holistic response but a new action coming from large intestine meridian.

To verify whether there are different responses on the left and right visors, we compared the difference between left and right visor and found quite similar changes during the acupuncture. There was a definite recovery on ipsilateral visor (right side) after withdrawing the needle but almost no recovery on the contralateral visor (left side), suggesting a tighter relation with the acupuncture on the right visor. This phenomenon supports more or less that the right branch of the large intestine meridian passes across the right visor.

No relative increase appeared on the remote facial area when giving laser acupuncture on Hegu. The difference versus that following needle acupuncture may be caused by a stronger neural activity from hand acupuncture, which can produce neural–interstitial fluid relaying transmission to remote areas whereas no or light neural activity was induced by laser needle through photo-chemical-neural process. Because the time of stimulation by laser needle was short and there were only a few subjects in this experiment, strong conclusions cannot be made for laser-needle acupuncture. Nonetheless, hand acupuncture had a better remote effect than non-feeling acupuncture. The result underlines the importance of Deqi feeling when treating a disease using points far from the disease area.

Laser-needle acupuncture is a newly developed high-tech acupuncture tool that is painless, safe, and adjustable, and is popular especially in Europe. Although a clear remote effect was not found, local effect has already been revealed by finding a release of histamine [8] and an increase of blood flow velocity on cerebral arteries [5]. Laser acupuncture should be regarded as a valid, complementary acupuncture that at least can be used in local points together with hand acupuncture used in remote points.

The experiment is part of a Sino-Austrian collaborative project “Basic Research and Clinic Trial on High-tech Acupuncture, Moxibustion, and Cupping Therapies” financially supported by China Academy of Chinese Medical Science.