Measuring arterial oxygen saturation from an intraosseous photoplethysmographic signal derived from the sternum

Abstract

Photoplethysmography performed on the peripheral extremities or the earlobes cannot always provide sufficiently rapid and accurate calculation of arterial oxygen saturation. The purpose of this study was to evaluate a novel photoplethysmography prototype to be fixed over the sternum. Our hypotheses were that arterial oxygen saturation can be determined from an intraosseous photoplethysmography signal from the sternum and that such monitoring detects hypoxemia faster than pulse oximetry at standard sites. Sixteen healthy male volunteers were subjected to incremental hypoxemia using different gas mixtures with decreasing oxygen content. The sternal probe was calibrated using arterial haemoglobin CO-oximetry (S a O 2 %). Sternal probe readings (S RH O 2 %) were then compared to S a O 2 % at various degrees of hypoxia. The time to detect hypoxemia was compared to measurements from standard finger and ear pulse oximeters. A significant association from individual regression between S RH O 2 % and S a O 2 % was found (r 2 0.97), Spearman R ranged between 0.71 and 0.92 for the different inhaled gas mixtures. Limits of agreement according to Bland-Altman plots had a increased interval with decreasing arterial oxygen saturation. The sternal probe detected hypoxemia 28.7 s faster than a finger probe (95% CI 20.0-37.4 s, p < 0.001) and 6.6 s faster than an ear probe (95% CI 5.3-8.7 s, p < 0.001). In an experimental setting, arterial oxygen saturation could be determined using the photoplethysmography signal obtained from sternal blood flow after calibration with CO-oximetry. This method detected hypoxemia significantly faster than pulse oximetry performed on the finger or the ear.

Oxygen saturation in intraosseous sternal blood measured by CO-oximetry and evaluated non-invasively during hypovolaemia and hypoxia – a porcine experimental study

“…Deep penetration of light into the tissues is required for non-invasive measurement of intraosseous blood flow. The depth of penetration depends on the geometry of the sensor, the chosen wavelength and the intensity of emitted light [8][9][10][11]. Numerous publications have demonstrated the possibility of non-invasive blood flow measurement in the bone tissue in various locations, e.g.…”

“…Numerous publications have demonstrated the possibility of non-invasive blood flow measurement in the bone tissue in various locations, e.g. patella, tibia, clavicle and sternum [8,9,[11][12][13][14]. The sternum has a central anatomical location and a high degree of vascularisation.…”

Enabling Continuous Wearable Reflectance Pulse Oximetry at the Sternum

“…Nevertheless, a few major challenges such limitations to the reflectance design, the presence of respiratory artifacts, and the malperfusion of the sternum pose difficulties to the adoption of chest-based approaches. Despite these challenges, prior evaluations have suggested that a chest-based approach might be feasible [ 3 , 11 , 12 , 13 , 14 , 15 ].…”

“…For example, either insufficient sample size (N = 1) in [ 11 ] or narrow dynamic range for SpO 2 (88–99%) in [ 12 ] limits the validity of the accuracy of their approaches. Meanwhile, Näslund et al [ 15 ] showed a strong agreement between their estimated SpO 2 and arterial oxygen saturation (SaO 2 ); however, their device was unable to capture the pulsatile component of the PPG signals and therefore might be susceptible to motion artifacts and skin pigmentation [ 17 ] (p. 34). Kramer et al [ 13 ] achieved accurate SpO 2 estimations (RMSE of 2.9%, N = 13), but their work lacks the key details necessary for replicating their algorithm such as preprocessing and feature extraction.…”

Respiratory rate monitoring in healthy volunteers by central photoplethysmography compared to capnography

“…The center-to-center distance between the light emitting diodes and the photodetectors of 20-22 mm facilitates monitoring of blood flow in deeper lying vessels in the sternum, which is supplied by the internal thoracic arteries and the anterior perforating branches of intercostal vessels. Changes in sternal blood volume in the due to local pressure variations during inhaling/exhaling are used to identify the respiratory pattern [20,32]. At the sternum, respiration-related changes in blood flow are noticeably stronger than at more peripheral locations [20], thus making signal detection and filtering relatively uncomplicated.…”