Research: Gluteal Muscle Tissue Vasculature

The idea of generating flow with a massaging motion (applied pressure gradient) depends on a superstructure of vascular tissue across the region of interest. For pressure ulcers, this area is gluteal muscle tissue under the ischial tuberosities and sacrum.

Branching which occurs parallel to the main artery and along the grain of the muscle tissue is the natural fluid pathway our device utilizes.

The main arteries to the gluteal muscles are the two arteries, pictured below.
(On the right, 5th & 6th label from the top)

The photo below shows a CT angiography of the pelvic vasculature:



These arteries are embedded in deep muscle and positioned superior to the seated high-pressure regions. This is actually somewhat far from the pressure points. Therefore, the vascular architecture that feeds the tissues of interest must be arterioles and capillaries. Fortunately, muscle tissue is highly vascularized naturally.

A macro-scale of vasculature is shown below through vascular tissue plastination. Note the parallel orientation of blood vessels at the skin and along the muscle tissues.

The micro-computed tomography angiogram shows the natural vasculature in muscle tissue on a mico-scale. 

The photo below shows capillary networks in muscle tissue.

The capillaries are quite small, as red blood cells pass through in a single-file line, but they are pervasive. They also flow at close to zero pressure, which makes it easy to drive flow with applied pressure. Another photo is provided below.

Embed from Getty Images

The photo below shows a 3D rendering of muscle tissue vasculature and red blood cells, based on micro-CT scanning.



Because of the abundance of vascular tissue in muscle, considering the distance of the pressure points from the nearest main artery, the parallel to grain structure orientation, and the low pressure required to produce flow in these tissues, it is reasonable to believe that an applied pressure gradient will generate nontrivial blood flow toward the seated pressure points.

References:

Gefen, A. (2007), The biomechanics of sitting-acquired pressure ulcers in patients with spinal cord injury or lesions. International Wound Journal, 4: 222–231. doi:10.1111/j.1742-481X.2007.00330.x

https://www.researchgate.net/figure/51768077_fig2_Images-of-the-capillary-network-of-the-soleus-muscle-in-control-A-and-GK-B-rats

http://www.flspinalcord.us/wp-content/uploads/arterial-anatomy-of-the-pelvis-and-lower-extremities-clinical-gate-inferior-vesical-artery.jpg

https://opentextbc.ca/anatomyandphysiology/chapter/20-3-capillary-exchange/

Doppler ultrasonography of the lower extremity arteries: anatomy and scanning guidelines Ultrasonography. 2017;36 (2): 111-119. Publication Date (Web): 2017 January 18 (Review Article)
doi: https://doi.org/10.14366/usg.16054

Zagorchev, Lyubomir & Oses, Pierre & Zhuang, Zhen & Moodie, Karen & Jo Mulligan-Kehoe, Mary & Simons, Michael & Couffinhal, Thierry. (2010). Micro computed tomography for vascular exploration. Journal of angiogenesis research. 2. 7. 10.1186/2040-2384-2-7.

Image-based modelling of skeletal muscle oxygenation
B. Zeller-Plumhoff, T. Roose, G. F. Clough, P. Schneider
J. R. Soc. Interface 2017 14 20160992; DOI: 10.1098/rsif.2016.0992. Published 15 February 2017