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A Novel Photoplethysmography Sensor for Vital Signs Monitoring from the Human Trachea

May, J.M., Phillips, J. P., Fitchat, T. , Ramaswamy, S., Snidvongs, S. & Kyriacou, P. A. ORCID: 0000-0002-2868-485X (2019). A Novel Photoplethysmography Sensor for Vital Signs Monitoring from the Human Trachea. Biosensors, 9(4), 119. doi: 10.3390/bios9040119


Current pulse oximeter sensors can be challenged in working accurately and continuously in situations of reduced periphery perfusion, especially among anaesthetised patients. A novel tracheal photoplethysmography (PPG) sensor has been developed in an effort to address the limitations of current pulse oximeters. The sensor has been designed to estimate oxygen saturation (SpO2) and pulse rate, and has been manufactured on a flexible printed circuit board (PCB) that can adhere to a standard endotracheal (ET) tube. A pilot clinical trial was carried out as a feasibility study on 10 anaesthetised patients. Good quality PPGs from the trachea were acquired at red and infrared wavelengths in all patients. The mean SpO2 reading for the ET tube was 97.1% (SD 1.0%) vs. the clinical monitor at 98.7% (SD 0.7%). The mean pulse rate for the ET sensor was 65.4 bpm (SD 10.0 bpm) vs. the clinical monitor at 64.7 bpm (SD 9.9 bpm). This study supports the hypothesis that the human trachea could be a suitable monitoring site of SpO2 and other physiological parameters, at times where the periphery circulation might be compromised.

Publication Type: Article
Additional Information: © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (
Publisher Keywords: photoplethysmography; sensing endotracheal tube; pulse oximetry; vital signs monitoring
Subjects: R Medicine
T Technology > TA Engineering (General). Civil engineering (General)
Departments: School of Science & Technology > Engineering > Electrical & Electronic Engineering
Text - Published Version
Available under License Creative Commons Attribution.

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