City Research Online

Abstract

A new system for measuring the oxygen saturation of blood within tissue has been developed, for a variety of patient monitoring applications. A particular unmet need is in the central nervous system, and this project aims to devise a means for measuring blood oxygen saturation in the brain tissue of patients recovering from neurosurgery or head injury. Coupling light sources and a photodetector to optical fibres results in a probe small enough to pass through a cranial bolt of the type already in use for intra-cranial pressure monitoring. The development and evaluation of a two-wavelength fibre-optic reflectance photoplethysmography (PPG) system are described. It was found that good quality red and near-infrared PPG signals could be obtained from the finger using a fibre-optic probe. Experiments were conducted to find the inter-fibre spacings that yield signals most suitable for calculating oxygen saturation. Reliable signals could be obtained for inter-fibre spacings between 2 mm and 5 mm, the latter being the size of the maximum aperture in the cranial bolt. A preliminary measurement from human brain tissue is also presented.

Publication Type:	Article
Publisher Keywords:	cerebral, brain, oximetry, photoplethysmography, fibre-optic, cranial bolt
Subjects:	R Medicine T Technology > TA Engineering (General). Civil engineering (General)
Departments:	School of Science & Technology School of Science & Technology > Engineering
SWORD Depositor:	Symplectic Administrator

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