Cerebral Arterial Oxygen Saturation Measurements Using a Fiber-Optic Pulse Oximeter
A pilot investigation was undertaken to assess the performance of a novel fiber-optic cerebral pulse oximetry system. A fiber-optic probe designed to pass through the lumen of a cranial bolt of the type used to make intracranial pressure measurements was used to obtain optical reflectance signals directly from brain tissue.
Short-duration measurements were made in six patients undergoing neurosurgery. These were followed by a longer duration measurement in a patient recovering from an intracerebral hematoma. Estimations of cerebral arterial oxygen saturation derived from a frequency domain-based algorithm are compared with simultaneous pulse oximetry (SpO2) and hemoximeter (SaO2) blood samples.
The short-duration measurements showed that reliable photoplethysmographic signals could be obtained from the brain tissue. In the long-duration study, the mean (±SD) difference between cerebral oxygen saturation (ScaO2) and finger SpO2 (in saturation units) was −7.47(±3.4)%. The mean (±SD) difference between ScaO2 and blood SaO2 was −7.37(±2.8)%.
This pilot study demonstrated that arterial oxygen saturation may be estimated from brain tissue via a fiber-optic pulse oximeter used in conjunction with a cranial bolt. Further studies are needed to confirm the clinical utility of the technique.
KeywordsPulse oximetry Saturation Cerebral Fiber-optic Cranial bolt
- 1.Hinds CJ, Watson JD. Intensive care: a concise textbook. 3rd ed. London: Saunders Ltd.; 2008.Google Scholar
- 14.Phillips JP, Kyriacou PA, George KJ, Priestley JV, Langford RM. An optical fiber photoplethysmographic system for central nervous system tissue. In: Conference Proceedings of Annual International Conference of the IEEE Engineering in Medicine & Biology Society, vol. 1, p. 803–6, 2006.Google Scholar
- 17.Barash PG, Cullen BF, Stoelting RK. Clinical anesthesia. 5th ed. Philadelphia: Lippincott Williams and Wilkins; 2006.Google Scholar
- 19.Moyle J. Pulse oximetry (principles and practice). 2nd ed. London: BMJ Books; 2002.Google Scholar