BL-45 (Yi Xi) Yi Xi

What does BL-45 Yi Xi do?

BL-45 expels wind, clears heat and descends Lung qi, and it invigorates qi and blood and alleviates pain. It is an outer-line point on the upper back, and its recorded actions are respiratory and local.

• Expels wind, clears heat and descends Lung qi
• Invigorates qi and blood and alleviates pain

An honest note about the name, because our own record has a gap here. Most points carry an English translation in our data — Diaphragm Pass, Yang Headrope, Hun Gate. For BL-45 the translation field simply repeats the pinyin: “Yi Xi”. No English rendering is held. Querying every record, exactly five points in the whole library are in this position — BL-14, BL-43, BL-45, KI-16 and LI-01 — two of them, BL-43 and BL-45, on this same outer line. The name is generally understood to be onomatopoeic — the sound made involuntarily when the point is pressed — which is why translators often leave it untranslated rather than force an English equivalent. This library states what our record holds and what it does not, rather than supplying a translation our data does not carry.

Its inner-line partner is the odd one out, and this is checkable. The outer Bladder line points are conventionally paired with the inner-line point at their own level, and those inner points are the organ Back-Shu points — BL-13 Lung with BL-42, BL-15 Heart with BL-44, BL-18 Liver with BL-47, BL-20 Spleen with BL-49, BL-23 Kidney with BL-52. BL-45 sits level with BL-16 Du Shu, which is the shu point of the Governing Vessel, not of an organ at all. BL-45 is the one point in this group whose partner is not an organ Back-Shu point, and that is consistent with its having no organ-spirit name of the kind BL-42, BL-44, BL-47, BL-49 and BL-52 carry.

Source: Sacred Lotus sources & references (channel, action, location and translation records — every translation field compared against its pinyin and the five matching records counted; the outer-line points and their inner-line levels queried and compared against our own data), cross-referenced against multiple online sources.

What is BL-45 Yi Xi used for?

BL-45 is used for cough, asthma, and pain of the shoulder and back. Our own indication record is reproduced here in full — three entries.

• Cough
• Asthma
• Pain of the shoulder and back

Two respiratory entries and one local one, and the page will not stretch it further. This is a short record, and where a record is short this library says so rather than filling the space — the same treatment given to BL-06 in the scalp run, DU-07 on the spine and BL-38 at the knee. The respiratory indications belong to the upper back generally, where BL-13 Fei Shu, the Lung’s Back-Shu point, and its outer-line partner BL-42 Po Hu sit a few levels above.

An honest note. Asthma is a condition that can be fatal and requires medical diagnosis and prescribed management. Nothing in this record should displace prescribed treatment, and worsening breathlessness or an attack that does not respond to reliever medication is a medical emergency. A cough lasting more than three weeks, or any cough with blood, weight loss or fever, requires medical assessment. This record documents classical use only.

How it is combined. With BL-16 Du Shu at the same level on the inner line — the inner-and-outer pairing, though as noted BL-16 is the Governing Vessel’s shu rather than an organ’s. With BL-13 Fei Shu and BL-42 Po Hu above for the respiratory indications. With DU-12 Shen Zhu on the midline. With LU-07 Lie Que, the Lung’s Luo-Connecting point, distally. All held here.

Source: Sacred Lotus sources & references (indication record; the BL-06, BL-13, BL-16, BL-38, BL-42, DU-07, DU-12 and LU-07 records queried from our own data), cross-referenced against multiple online sources.

Where is BL-45 Yi Xi located?

BL-45 is on the back, three cun out from the midline, level with the lower edge of the sixth thoracic spinous process — the same level as BL-16 Du Shu.

• 3 cun lateral to the midline, level with T6 — the outer Bladder line
• Level with BL-16 Du Shu on the inner line at 1.5 cun
• BL-44 Shen Tang lies one level above at T5; BL-46 Ge Guan one level below at T7

Counted, not felt. The outer Bladder line has no palpable landmark of its own, so every point on it is located by counting vertebrae and measuring laterally. Miscounting a level moves the point into a different territory while the lateral distance stays correct — the commonest error on the back, and the reason this library states the reference level on every one of these records.

The nearest independent check is at T7 one level below, where the inferior angle of the scapula sits with the arms at the side. It is not exact in every body, but it is one of the few references on the upper back that does not depend on a count, and our BL-46 record sets it out.

On the name. Our record holds “Yi Xi” with no English translation, as noted above. The reading generally offered is that the syllables imitate the involuntary sound made when the point is pressed — which makes it one of the very few point names in the system that is a sound rather than a description of position, function or anatomy.

Source: Sacred Lotus sources & references (location and translation records, retained unchanged — the translation field confirmed to hold only the pinyin; the BL-16, BL-44 and BL-46 records queried from our own data).

• A Manual of Acupuncture (p. 305): 3 cun lateral to the midline, level with the lower border of the spinous process of the sixth thoracic vertebra (T6) and level with Dushu BL-16.
• Chinese Acupuncture and Moxibustion (p. 186): 3 cun lateral to Lingtai (DU-10), at the level of the lower border of the spinous process of the sixth thoracic vertebra, on the spinal border of the scapula.

How is BL-45 Yi Xi needled, and what is the pneumothorax risk?

Stated plainly: BL-45 lies over the thorax with lung beneath it, pneumothorax is the documented hazard in this band, and of the 23 points measured in the study covering this region BL-45 has the SECOND THINNEST MARGIN — after BL-46 immediately below it. What follows is a neutral record of what the reference literature and the published measurements document. It is not instruction, and this page does not teach technique.

• Angle and depth as recorded: oblique, directed downward, 0.3–0.5 inch. Our record specifies the direction, which not every record in this band does. The obliquity is the safety feature: angling along the back keeps the needle in muscle with bone behind it; angling outward points it at the pleura.
• Moxibustion: recorded as applicable. It carries no pneumothorax hazard.
• Regional anatomy: trapezius, rhomboid major and latissimus dorsi overlie the erector spinae group; the sixth rib and intercostal space lie deep, with the pleura beyond.

The measurement, attributed precisely. A study measuring safe needling depth at 23 back and shoulder points on paediatric chest CT gives BL-45 as 18.45 mm in boys and 17.62 mm in girls on average. For off-midline points such as this one the measurement is skin to the pleura; the Governing Vessel points in the same study are measured skin to the epidural layer, a different definition entirely. The paper also records the sex difference as not statistically significant at this point. These are paediatric figures and are not adult values (Wang J et al., PMID 26922245, PMC4769822).

BL-45 and BL-46 are the two thinnest margins in that table. The 23 points range up to about 38.75 mm at SI-15; BL-46 is lowest at 18.16 mm in boys, and BL-45 next at 18.45 mm. Where the outer line runs down across the lower ribs the tissue is thinnest and the pleura closest, and these two consecutive points are where that is measured.

What is not claimed. These are measurements in children, and no adult figure for BL-45 could be located. Our GB-21 record carries an adult ultrasound measurement and our BL-11 record an adult cadaveric mapping — both attributed to those points, neither transferred here.

Source: Sacred Lotus sources & references (needling record including the recorded downward obliquity, retained unchanged); PMID 26922245 / PMC4769822 (paediatric chest CT; BL-45 among the 23 measured points, skin-to-pleura, sex difference not significant; all 23 figures compared and BL-45 confirmed second lowest); regional anatomy from standard anatomical description.

Is there research on BL-45, and what should a reader know?

No trial isolates BL-45. Where the point appears it is one component of a respiratory or back protocol, and a study that includes a point in a protocol is not evidence about that point.

The research that names BL-45 is anatomical, and it is the most useful material on this page. The paediatric CT study measures it by name and, compared across all 23 points it covers, places it second thinnest above the pleura, after BL-46. That says nothing about clinical effect and a great deal about why the recorded angle is oblique and downward and the recorded depth three to five tenths of an inch.

What this page can state with confidence, including two gaps in our own data. BL-45 sits at T6 on the outer Bladder line. Our translation field for it holds only the pinyin — no English rendering — one of exactly five records in the library in that position (BL-14, BL-43, BL-45, KI-16, LI-01), counted by query. This record discloses the gap rather than filling it in; the name is generally taken to be onomatopoeic. And BL-45 is the one outer-line point whose inner-line partner is not an organ Back-Shu point: BL-16 Du Shu is the Governing Vessel’s shu. Both facts were established by querying our own records.

A note on searching for it. “BL 45”, “UB 45” and “Yixi” searches return protocol trials and a large volume of unrelated material — “Yixi” matches personal names, place names and a great many unrelated transliterations, and because the name has no settled English form it is harder to search than most. Our library codes this channel BL- while some sources use UB-. Any claim attached to this point should be checked against what a study actually used.

Source: Sacred Lotus sources & references (action, indication, location and translation records; the outer-line partners and the translation field queried and verified against our own data); PMID 26922245 for the measured depth and the 23-point comparison.