The development of a device to record spinal cord blood flow during surgery

Pressure on the spinal cord during fusion surgeries can lead to loss of spinal cord blood flow. The Spinal Blood Flow Monitor (SBFM) provides efficient and compact monitoring of anterior spinal artery blood flow. Current flow monitoring methods are slow, which can result in post-operative motor deficit or paralysis. Intra-operative monitoring using the SBFM can rapidly alert surgeons to blood flow decreases, improving post-surgical outcomes.

Laser doppler flowmetry (LDF) has shown great promise in measuring relative flow rates in confined spaces using affordably sourced components. The anterior spinal artery runs approximately 7 mm below the posterior spinal cord surface midline in the spinal canal.
Using a near-infrared laser allows light penetration of up to 10 mm and enables the fabrication of a less than 5 mm flexible assembly that can be sterilized with medical-grade ethylene oxide.

The SBFM uses a dual optical fiber probe that sends and receives near-infrared light that is scattered by red blood cells depending on their velocity. A photodiode converts received light into an electrical signal that an Arduino converts to a digital signal to send to a medical computer. There it is processed and displayed to give real-time blood flow measurements at the probe site. Multiple probes can be used in parallel at different levels of the spine to pinpoint the location of spinal pinching for more diagnostic utility.