The Feasibility of Flat, Portable and Wireless Device for Non-Invasive Peripheral Oxygenation Measurement over the Entire Body

Peripheral oxygenation level (SpO2) can provide vital information on body functions. Continuous monitoring facilitates effective diagnosis and treatment and can even be lifesaving. Clinical device monitor SpO2 using a clip, and measure light transmission through the tissue. This method limits the body locations of the clip’s placement and is sensitive to body movement, which hampers continuous SpO2 monitoring during wakefulness or sleep, thus decreasing its usability in clinics and its accessibility in homecare usage. We developed a portable, wireless, flat and low cost prototype for continuous monitoring of SpO2 that overcomes those limitations. The prototype enables convenient measurement in larger variety of body locations by spectrophotometric measurements of changes in the optical reflectance unlike other device that measure absorption through the tissue. The original design and signal processing enable reliable signal acquisition, synchronization and control. An Android’s application was developed to provide a user friendly interface for results display on smartphones. The prototype’s measurements were compared to commercial device that simultaneously measured heart rate frequency, transcutaneous oxygen tension (tcPO2) and SpO2. The prototype’s measurements accurately reflected changes caused by blood pulses, were correlated to the heart rate, and were sensitive to changes in oxygen saturation. Excellent real time behavior and synchronization were demonstrated between the hardware and smartphone software. Our prototype thus enables convenient SpO2 measurement over the entire body, while maintaining accuracy comparable to commercial device. Its smartphone application enables accessible and understandable results display to patients, care-givers and healthcare professionals. The application’s display and alert calibration flexibility facilitates the prototype’s usage in changing medical requirements and for various disease and conditions. A device based on this prototype can monitor continuously and accurately patients’ SpO2 without limiting their everyday activities or disturbing their sleep and can thus significantly im-prove their medical care in both clinics and home.

Oxygenation target in acute respiratory distress syndrome

Determining oxygenation targets in acute respiratory distress syndrome(ARDS)remains a challenge.Althoughoxygenation targets have been used since ARDS was first described,they have not been investigated in detail.However,recent retrospective and prospective trials have evaluated the optimal oxygenation threshold in patientsadmitted to the general intensive care unit.In view of the lack of prospective data,clinicians continue to relyon data from the few available trials to identify the optimal oxygenation strategy.Assessment of the cost-benefitratio of the fraction of inspired oxygen(FiO_(2))to the partial pressure of oxygen in the arterial blood(PaO_(2))is an additional challenge.A high FiO_(2) has been found to be responsible for respiratory failure and deaths innumerous animal models.Low and high PaO_(2) values have also been demonstrated to be potential risk factors inexperimental and clinical situations.The findings from this literature review suggest that PaO_(2) values rangingbetween 80 mmHg and 90 mmHg are acceptable in patients with ARDS.The costs of rescue maneuvers needed toreach these targets have been discussed.Several recent papers have highlighted the risk of disagreement betweenarterial oxygen saturation(SaO_(2))and peripheral oxygen saturation(SpO_(2))values.In order to avoid discrepanciesand hidden hypoxemia,SpO_(2) readings need to be compared with those of SaO_(2).Higher SpO_(2) values may beneeded to achieve the recommended PaO_(2) and SaO_(2) values.

Screening Coarctation of Aorta with Clinical and Echocardiographic Profiles in Infants:A Pilot Study

Aim:To determine the profiles of clinical features including four-limb blood pressure(BP),saturations of peripheral oxygen(SpO2),and echocardiographic features in infants with coarctation of aorta(CoA)to facilitate congenital heart diseases screening.Methods:The charts of infants with CoA were retrospectively reviewed.All in-hospital infants suspected of congenital heart diseases by clinical teams were prospectively measured of four limbs BPs and SpO2 in a regional cardiac transferring center during 2013 and 2019.Echocardiography as a gold standard test was followed within 2 days after suspicion.All infants were divided into non-significant CoA group or significant CoA group based on the difference of BPs between right arm and lower limbs.Predictors of nonsignificant CoA were determined with multivariable logistic regression.Results:One hundred thirty-three infants with CoA were identified.The BPs on upper limbs were higher than those on lower limbs(P=0.001).No statistical difference in SpO2 was found between four limbs.Fifty-three(39.8%)infants presented with significant CoA.Thirty-four infants presented with low SpO2 and 26 of 34 presented with non-significant CoA.Small ascending aorta diameter[0.070(95%CI:0.005–0.136),P=0.036]was an independent risk factors for non-significant CoA.Eighteen(13.5%)infants with CoA didn’t present with any of the BP difference,low SpO2,murmur,or weak femoral pulse.Conclusion:Less than half of the infants with CoA presented with a significant BP difference.Another one fifth presented with low SpO2.Small ascending aorta diameter was an independent factor for non-significant CoA.

Design of Calibration Device for Pulse Oximeter Simulator

Saturation of peripheral oxygen （SpO2） is one of the most important parameters of vital signs. Pulse oximeter based on near-infrared spectroscopy is commonly used as a non-invasive method to measure SpO2 yl. Currently, medical device manufacturers as well as metrology measurement agencies in China usually use pulse oximeter simulator as the commonly accepted functional calibration equipment for pulse oximeters. So far, no experimental protocol or devices can be used to test the accuracy and reliability of a pulse oximeter simulator. Therefore, a set of new metrology apparatus with the name of calibration device for pulse oximeter simulator have been designed in order to make a traceable system for the calibration or verification of pulse oximeter simulators. The principles and some research methods of this calibration device for pulse oximeter simulator will be discussed in this paper. Besides that, many experiments have been applied in order to guarantee the accuracy as well as traceability of this set of device.