Measurement Of Blood Oxygen Saturation Research Articles

Comparison of Closed Kinetic Chain Exercises and Conventional Therapy on Cardiac Parameters in Post CABG Subjects

Introduction: Cardiovascular disorders are public health problems worldwide. In industrialized world they are the leading cause of morbidity and mortality. Coronary artery bypass grafting (CABG) has proved to be a major life saving operative method in cardiovascular disease. Physiotherapy interventions play major role in rehabilitation post CABG so the study was conducted with the aim to find the effect of closed kinetic chain exercises and conventional therapy on cardiac parameters in post CABG subjects. Method: In this comparative study 20 subjects were treated for post CABG subjects between the age group of 40-50 years. Group A were given conventional treatment and Group B were given Closed Kinetic Chain exercise. The pre and post -test was measure blood pressure, respiratory rate, heart rate, oxygen saturation and borg scale. Results: The statistical analysis for conventional therapy pre and post week1 day 1-systolic blood pressure(p=<0.0001), diastolic blood pressure(p=0.005), respiratory rate(p=0.001), heart rate(p=0.011), oxygen saturation(p=0.081) and borg scale(p=0.003). pre and post week6 day 3- diastolic blood pressure(p=0.018), respiratory rate(p=<0.0001), heart rate(p=0.005), systolic blood pressure(p=0.186), oxygen saturation(p=0.343) and borg scale(p=0). The statistical analysis for experimental group pre and post week1 day 1-heart rate (p=0.01) diastolic blood pressure(p=0.002), systolic blood pressure(p=<0.0001), respiratory rate(p=<0.0001),borg scale(p=0.0007), oxygen saturation (p=0.508). pre and post week6 day 3-borg scale(p=0), diastolic blood pressure(p=0.051),heart rate (p=<0.0001), respiratory rate(p=<0.0001), systolic blood pressure(p=0.26) and oxygen saturation(p=0.34).The study had found that conventional therapy is more effective than experimental group. Conclusion: The study concluded that conventional treatment is more effective than closed kinetic chain exercises. However, it cannot be stated that CKC has no effect because of its additional benefits on functional capacity (improve joint integrity). Therefore, it can be concluded that further studies can evaluate the improvement noted with a right combination of both and obtain greater benefit

Noninvasive optical measurement of microvascular cerebral hemodynamics and autoregulation in the neonatal ECMO patient.

BackgroundExtra-Corporeal Membrane Oxygenation (ECMO) is a life-saving intervention for severe respiratory and cardiac diseases. However, 50% of survivors have abnormal neurologic exams. Current ECMO management is guided by systemic metrics, which may poorly predict cerebral perfusion. Continuous optical monitoring of cerebral hemodynamics during ECMO holds potential to detect risk factors of brain injury such as impaired cerebrovascular autoregulation (CA).MethodsWe conducted daily measurements of microvascular cerebral blood flow (CBF), oxygen saturation, and total hemoglobin concentration using diffuse correlation spectroscopy (DCS) and frequency-domain diffuse optical spectroscopy in 9 neonates. We characterize CA utilizing the correlation coefficient (DCSx) between CBF and mean arterial blood pressure (MAP) during ECMO pump flow changes.ResultsAverage MAP and pump flow levels were weakly correlated with CBF and were not correlated with cerebral oxygen saturation. CA integrity varied between individuals and with time. Systemic measurements of MAP, pulse pressure, and left cardiac dysfunction were not predictive of impaired CA.ConclusionsOur pilot results suggest that systemic measures alone cannot distinguish impaired CA from intact CA during ECMO. Furthermore, optical neuromonitoring could help determine patient-specific ECMO pump flows for optimal CA integrity, thereby reducing risk of secondary brain injury.

Improved oxygen systems at hospitals in three Nigerian states: An implementation research study.

Hypoxemia is a life-threatening condition and is commonly seen in children with severe pneumonia. A government-led, NGO-supported, multifaceted oxygen improvement program was implemented to increase access to oxygen therapy in 29 hospitals in Kaduna, Kano, and Niger states. The program installed pulse oximeters and oxygen concentrators, trained health care workers, and biomedical engineers (BMEs), and provided regular feedback to health care staff through quality improvement teams. The aim of this study is to evaluate whether the program increased screening for hypoxemia with pulse oximetry and prescription of oxygen for patients with hypoxemia. The study is an uncontrolled before-after interventional study implemented at the hospital level. Medical charts of patients under 5 admitted for pneumonia between January 2017 and August 2018 were reviewed and information on patient care was extracted using a standardized form. The preintervention period of this study was defined as 1 January to 31 October 2017 and the postintervention period as 1 February to 31 August 2018. The primary outcomes of the study were whether blood-oxygen saturation measurements (SpO2 ) were documented and whether children with hypoxemia were prescribed oxygen. A total of 3418 patient charts were reviewed (1601 during the preintervention period and 1817 during the postintervention period). There was a significant increase in the proportion of patients with SpO2 measurements after the interventions were conducted (adjusted odds ratio [aOR] 5.0; 4.3-5.7, P < .001). Before the interventions, only 13.7% (95% confidence interval [CI]: 12.2-15.3) of patients had SpO2 measurements and after the interventions, 82.4% (95% CI: 80.7-84.1) had SpO2 measurements. Oxygen administration for patients with clinical signs of hypoxemia also increased significantly (aOR 5.0; 4.2-5.9, P < .001)-from 22.8% (95% CI: 18.8-27.2) to 77.9% (95% CI: 73.9-81.5). Increasing pulse oximetry and oxygen therapy access and utilization in a low-resourced environment is achievable through a multifaceted program focused on strengthening government-owned systems.

Interstitial diffuse optical probe with spectral fitting to measure dynamic tumor hypoxia

Understanding the dynamic nature of tumor hypoxia is vital for cancer therapy. The presence of oxygen within a tumor during radiation therapy increases the likelihood of local control. We used a novel interstitial diffuse optical probe to make real-time measurements of blood volume fraction and hemoglobin oxygen saturation within a tumor at a high temporal resolution. This device was initially characterized and benchmarked using a customized vessel designed to control hemoglobin oxygen saturation and blood volume in a solution of blood with different concentrations of an oxygen scavenger, tetrakis (hydroxymethyl) phosphonium chloride. The optical device was found to consistently monitor the changes in oxygen saturation and these changes correlated to the concentration of the oxygen scavenger added. In near-simultaneous measurements of blood volume and oxygen saturation in tumor-bearing mice, the changes in blood volume fraction and oxygen saturation measured with the interstitial diffuse optical probe were benchmarked against photoacoustic imaging system to track and compare temporal dynamics of oxygen saturation and blood volume in a patient-derived xenograft model of hypopharyngeal carcinoma. Positive correlations between our device and photoacoustic imaging in measuring blood volume and oxygen saturation were observed.

Non-contact blood oxygen saturation measurement by spectroscopy

Non-contact blood oxygen saturation measurement by spectroscopy

Measurement device for detecting oxygen saturation in blood, heart rate, and temperature of human body

The progress of science and technology must be able to help resolve human medical problems for human survival. In this study, integrated measurement of oxygen saturation in the blood, heart rate and temperature of the human body have been made into one tool whose measurement results are displayed directly on the LCD display on a measuring instrument and an Android Smartphone. This tool uses Arduino Nano as its Microcontroller, Bluetooth as wireless serial communication with Android smartphone, Android Application Made with MIT App Inventor, MAX30100 sensor is used to measure blood oxygen saturation and heart rate, and MLX90614 sensor to measure body temperature. Testing Measurements that have been made are calibrated with Industrial standard measuring instruments (Oximeters) and digital thermometers. The result is that the accuracy of the tool reaches 99.62% for blood oxygen saturation measurements, 97.55% for heart rate, and 99.62% for body temperature when compared with industry standard devices. Android applications have been successfully installed on 5 types of smartphones with different brands and specifications. The Bluetooth range of a measuring device for a smartphone in maximum data transfer is 29 meters without a hitch and a maximum of 21.5 meters with obstacles.

Deep spectral learning for label-free optical imaging oximetry with uncertainty quantification

Measurement of blood oxygen saturation (sO2) by optical imaging oximetry provides invaluable insight into local tissue functions and metabolism. Despite different embodiments and modalities, all label-free optical-imaging oximetry techniques utilize the same principle of sO2-dependent spectral contrast from haemoglobin. Traditional approaches for quantifying sO2 often rely on analytical models that are fitted by the spectral measurements. These approaches in practice suffer from uncertainties due to biological variability, tissue geometry, light scattering, systemic spectral bias, and variations in the experimental conditions. Here, we propose a new data-driven approach, termed deep spectral learning (DSL), to achieve oximetry that is highly robust to experimental variations and, more importantly, able to provide uncertainty quantification for each sO2 prediction. To demonstrate the robustness and generalizability of DSL, we analyse data from two visible light optical coherence tomography (vis-OCT) setups across two separate in vivo experiments on rat retinas. Predictions made by DSL are highly adaptive to experimental variabilities as well as the depth-dependent backscattering spectra. Two neural-network-based models are tested and compared with the traditional least-squares fitting (LSF) method. The DSL-predicted sO2 shows significantly lower mean-square errors than those of the LSF. For the first time, we have demonstrated en face maps of retinal oximetry along with a pixel-wise confidence assessment. Our DSL overcomes several limitations of traditional approaches and provides a more flexible, robust, and reliable deep learning approach for in vivo non-invasive label-free optical oximetry.

A Low-Power Dynamic-Range Relaxed Analog Front End for Wearable Heart Rate and Blood Oximetry Sensor

Photoplethysmogram (PPG) is widely implemented to monitor heart rate and oxygen saturation in wearable body sensor networks for healthcare management. This paper presents a low-power analog front end that enables PPG signal acquisition. By implementing a high-pass function, the ac and dc components of PPG signal are separately extracted to calculate heart rate and oxygen saturation, and the dynamic range requirement of the readout channel is relaxed. In addition, the chopping modulation is implemented to ensure the low-noise operation. The analog front-end circuit is designed and fabricated in the CMOS 0.18- $\mu \text{m}$ standard technology. The measurements show that the consuming power is approximately $180~\mu \text{W}$ at a supply of 2.5 V. The circuit achieves an input noise of 6.45 pArms. The calibrated algorithm is implemented using a Cortex-M3 MCU, and the demonstration, which is compared with the FLUKE Simulator as the reference, shows that the heart rate is accurately detected, and the error of the measured blood oxygen saturation is less than 1.5%.

Relating glaucomatous visual field loss to retinal oxygen delivery and metabolism.

To test the hypothesis that visual field (VF) loss is associated with decreased retinal blood flow, oxygen delivery and metabolism, and with increased retinal oxygen extraction fraction (OEF) in glaucomatous individuals. Glaucomatous subjects underwent automated perimetry, dual wavelength scanning laser ophthalmoscopy and Doppler optical coherence tomography imaging in order to measure mean deviation, central retinal arterial and venous diameter equivalents (CRAE and CRVE), oxygen saturation levels and total retinal blood flow (TRBF), respectively. Retinal oxygen delivery, metabolism and extraction fraction were derived from measurements of oxygen saturation and blood flow. Twenty eyes of 14 subjects were included in the study. Mean deviation was on average -13.76±8.70 dB. Mean CRAE and CRVE were 126±28 and 191±35μm, respectively. Mean TRBF and oxygen delivery were 34.3± 11.7μl/min and 6.5±2.6μl O2 /min, respectively. Mean oxygen metabolism and extraction fraction were 2.1±0.94μl O2 /min and 0.34±0.15, respectively. Visual field (VF) loss was associated with reduced CRAE and CRVE, TRBF and oxygen delivery and associated with increased OEF. Combined measurements of retinal blood flow and oxygen saturation in glaucomatous individuals suggest VF loss is associated with impaired oxygen delivery and augmented OEF.

Use of pulse oximetry during initial assessments of children under five with pneumonia: a retrospective cross-sectional study from 14 hospitals in Ethiopia.

BackgroundHypoxemia, a fatal condition characterized by low concentration of oxygen in the blood, is strongly associated with death among children with pneumonia. Ethiopia’s Federal Ministry of Health launched its first National Oxygen and Pulse Oximetry Scale-up road map to improve access and utilization of pulse oximetry and oxygen. This study aimed to describe the use of pulse oximetry during the initial patient assessment among children under five diagnosed with pneumonia and serves as a benchmark to measure progress of the road map.MethodsThe study design was an observational study using retrospective review of patient medical records at 14 hospitals. Medical records of 443 children age 0-59 months with a primary diagnosis of pneumonia were randomly selected for review. The primary outcome was whether an arterial blood oxygen saturation (SpO2) measurement was recorded in the patient’s medical record at the initial assessment.ResultsOverall, 10% (95% confidence interval CI = 4%-22%) of patient medical records had a SpO2 measurement. Admitted patients were more likely to have a SpO2 measurement recorded in their medical records than patients treated in the outpatient department (P<0.01). Among admitted patients, 19% (95% CI = 8%-38%) had a SpO2 measurement compared to 3% (95% CI = 1%-11%) of patients treated in the outpatient department.ConclusionIn Ethiopia, patients under five with a primary diagnosis of pneumonia are rarely screened for hypoxemia with a pulse oximeter, and hypoxemia may be severely underdiagnosed. Much needs to be done to improve the routine use of pulse oximetry.

Feasibility of Commercially Marketed Health Devices for Potential Clinical Application.

Concerns have been raised regarding the lack of validation on consumer-marketed health-monitoring devices. An investigation to characterize current health monitoring devices was carried out in the laboratory using widely accepted clinical and industry criteria. In total, 16 unique devices were examined. These devices were assessed according to their sensing modalities: step count, blood pressure, body temperature, electrocardiogram, blood oxygen saturation, and respiratory rate. Devices were tested at rest and immediately following exercise. Our results revealed that only four devices meet target requirements for accuracy. The AliveCor, a portable ECG monitor, accurately detected the heart rate for 87% of all recordings. To meet the target criterion for accuracy, the heart rate must be within ± 5 beats/minute or 10% of the standard measurement, whichever is lower. The Withings Pulse Ox, the Tinké, and the Santamedical SM-110 measured blood oxygen saturation with 2.1, 2.6, and 1.4 root-mean-square (rms) error, respectively. For blood oxygen saturation, the device should demonstrate rms error of < 3%. However, the Withings Pulse Ox and the Tinké failed to meet the accuracy criteria for their alternative biosensing capabilities: step count and respiratory rate, respectively. We conclude that the use of consumer-marketed health-monitoring devices for clinical or medical purposes should be undertaken with caution, especially in the absence of FDA or comparable clearance.

Use of bi-level pulsed frequency-division excitation for improving blood oxygen saturation precision

The measurement of blood oxygen saturation (SpO2) plays an increasingly key role in medical monitoring and health detection. In order to improve SpO2 precision, this paper proposes a new method, namely bi-level pulsed frequency-division excitation (BPFDM), which uses 200 Hz and 400 Hz bi-level pulse to excite two LEDs and then utilizes the digital demodulation algorithm to synchronously obtain dual-wavelength photoplethysmogram (PPG) signals. The principle of BPFDM is theoretically analysed, and the effectiveness is illustrated by the contrast experiments among time-division method (TDM), frequency-division (FDM) and BPFDM. The experimental results show that BPFDM gets the highest SNR and the least root mean square error (RMSE) of SpO2% value. Compared with TDM and FDM, the SNR of BPFDM increases by 11 dB and 5 dB, and the RMSE of BPFDM reduces by 58% and 25%, respectively. So, BPFDM can significantly improve the SNR of PPG signal and SpO2 precision under the same hardware and software conditions, which is valuable for the application in pulse oximeter.

Retinal perfusion changes in radiation retinopathy.

To investigate retinal blood flow and oxygen saturation changes in patients diagnosed with retinopathy following plaque radiation treatment to treat choroidal melanoma. Eight patients (mean age 55.75years, SD 12.58years) who have developed unilateral ischaemic radiation-related retinopathy as confirmed by wide-field fluorescein angiography were recruited for the study. The fellow eye with no other ocular or retinal pathology was used as control. Both eyes underwent measurement of total retinal blood flow (TRBF) and retinal blood oxygen saturation using prototype methodologies of Doppler Spectral Domain Optical Coherence Tomography (OCT) and Hyperspectral Retinal Camera, respectively. The average TRBF in the retinopathy eye was significantly lower compared to the fellow eye (33.48±12.73μl/min versus 50.37±15.26μl/min; p=0.013). The arteriolar oxygen saturation (SaO2 ) and venular oxygen saturation (SvO2 ) were higher in the retinopathy eye compared to the fellow eye (101.11±4.26%, versus 94.45±5.79%; p=0.008) and (62.96±11.05% versus 51.24±6.88%, p=0.051), respectively. The ionizing radiation seems to have an impact on the TRBF, SaO2 and SvO2 , clinically presenting similar to a rapidly developing diabetic retinopathy. The results show an altered retinal vascular physiology in patients with radiation-related retinopathy.

The Development of Spectroscopy System for Non-Invasive Measurement of Skin Blood Oxygen Saturation

This paper presents the use of the developed spectroscopic system for noncontact measurement of one’s skin blood oxygen saturation (StO2). This study employed light diffusion model in the prediction of the required value using light source of wavelength 488 nm, 522 nm and 684 nm. The performance of this system was tested on ten volunteers of different skin tone to investigate the robustness of the system. The mean and standard deviation of StO2 value calculated for the recruited subjects is given by 71 ± 4.7 %. The results revealed differences in the predicted value with the recruits’ skin tone. This work concluded that the developed system may potentially be used in clinical settings to determine skin oxygen saturation and to monitor wound healing progress.

A Low-Power Dynamic-Range Relaxed Analog Front End for Photoplethysmogram Acquisition.

This paper presents a low-power analog front-end that enables photoplethysmographic signals acquisition, the dynamic range for AC component exaction is relaxed with simple high-pass implementation. The chopping modulation ensures the low-noise operation. The circuit is fabricated in a 0.18-um CMOS technology. Measurements show that the consuming current is approximately 72 uA at a supply of 2.5 V. The circuit achieves a input noise of 6.45 $\mathrm{pA}/\sqrt{Hz}$. The calibred algorithm is implemented by means of MCU, and the demonstration that is compared with the Fluck Simulator used as the reference shows the heart rate is accurately detected, and the error of the measured blood oxygen saturation is less than 1.5%.

Measurement of blood-oxygen saturation using a photoacoustic technique in the rabbit hypoxemia model.

The golden standard method to obtain accurate blood oxygen saturation is blood gas analysis that needs invasive procedure of blood sampling. Photoacoustic technique enables us to measure real-time blood oxygen saturation without invasive procedure. The aim of this study is to use the photoacoustic technique, an optical method, for accurately determining oxygen saturation in vivo. We measured induced photoacoustic signals of arterial blood in the rabbit model of stable hypoxemia after irradiation at 750 and 800nm. Oxygen saturation was calculated from the photoacoustic signals using two calibration curves. Calibration curve 1 is a conventional curve derived from the absorbance coefficient of hemoglobin, whereas calibration curve 2 is derived from the photoacoustic signals obtained from the original blood vessel model. Simultaneously, blood-gas analysis was performed to obtain the reference standard of oxygen saturation. Regression analysis and Bland-Altman analysis were performed to assess the accuracy of oxygen saturation obtained using the two methods. The oxygen saturation calculated using calibration curves 1 and 2 showed strong correlations with the reference standard in regression analysis (R = 0.965, 0.964, respectively). The Bland-Altman analysis revealed better agreement and precision with calibration curve 2, whereas there was significant underestimation of values obtained using calibration curve 1. Photoacoustic measurement of oxygen saturation using calibration curve 2 provided an accurate estimate of oxygen saturation, which was similar to that obtained using a portable blood-gas analyzer.

Order effect when comparing usability of two telehealth remote monitoring technology solutions

An experienced healthcare device evaluator collaborated with a human factors scientist to develop and conduct a usability test of two different telehealth remote monitoring solutions as part of a larger technology evaluation. Twenty-one participants used each of the telehealth platforms to capture and transmit data. Typically users of telehealth platforms capture and send their own data, however, we asked our participants to place a bag of sand on wirelessly connected scales to capture weight information and to place the wireless pulse oximeters on the healthcare device evaluator’s index finger to get blood oxygen saturation measurements. This protocol enabled participants to go through the processes required to capture and share representative data without providing any of their own personal health data. After using each solution to complete the same series of three tasks, participants filled out the System Usability Scale (SUS) questionnaire. We intended to compare SUS scores within-subjects, but discovered that the SUS scores for the second solution were not independent. In particular, the participants who used the system that was harder to use second produced SUS scores for that system that were significantly lower than the participants who rated that system first. We conclude that it may not be appropriate to use a within-subjects design if experimenters plan to compare the SUS scores for different systems.

Near-Real-Time Detection of Pulse Oximeter PPG Peaks Using Wavelet Decomposition

Abstract Pulse oximeters are frequently used to provide real time measurements of heart rate and blood oxygen saturation (SpO2). SpO2 is calculated by taking the ratio of the AC to DC components of the photoplethysmograph (PPG) signal measured by the pulse oximeter. For accurate estimation of SpO2, the AC component needs to be extracted from the signal through signal processing, where accurate peak detection is a crucial, difficult element. This paper investigates the use of the wavelet transform for real time signal processing to detect peaks that could be unintentionally attenuated through more conventional filtering methods. Four mother wavelets (Daubechies 3, symlets 2, coiflets 3 and reverse biorthogonal 1.5) were tested against each other to determine the wavelet with the best representation of the PPG signal in a noisy environment (SNR of 6.44). The reverse biorthogonal (rbio1.5) mother wavelet was found to better represent the PPG signal with a specificity of 0.97 and a sensitivity of 0.97. Further research into the decomposition depth of the rbio1.5 wavelet resulted in an optimal depth of 3, with the 2nd and 3rd levels being used for reconstruction of the signal. Using a wavelet length of 128 samples resulted in a time delay of 2.56 seconds. This time delay is well within clinical requirements for near real-time-signal analysis involving these devices.

Development and optimization of a miniaturized fiber-optic photoplethysmographic sensor

Photoplethysmography (PPG) is a widely used technique for measuring blood oxygen saturation, commonly using an external pulse oximeter applied to a finger, toe, or earlobe. Previous research has demonstrated the utility of direct monitoring of the oxygen saturation of internal organs, using optical fibers to transmit light between the photodiode/light emitting diode and internal site. However, little research into the optimization and standardization of such a probe has yet been carried out. This research establishes the relationship between fiber separation distance and PPG signal, and between fiber core width and PPG signal. An ideal setup is suggested: 1000-μm fibers at a separation distance of 3 to 3.5 mm, which was found to produce signals around 0.35 V in amplitude with a low variation coefficient.

THE BIOPHYSICAL PARAMETER MEASUREMENTS FROM PPG SIGNAL

Early investigation on blood circulation by Hertzman (1937) leads to the observation of vital body signs such as respiration rate, heart rate (HR), blood oxygenation and vascular assessment using photoplethysmographic (PPG) device. PPG is a noninvasive, painless optical technique used to monitor the pulsations linked to alteration in the blood volume. The PPG waveform is a summation of pulsatile and nonpulsatile components and contains useful information about the physiological systems. With the breakthrough in technology and development of powerful analytical tools, PPG devices are constantly being used in advanced medical equipments such as smart-watches and smart-wristbands for HR monitoring, pulse oximeters for measuring respiratory rate and noncontact PPG device for blood oxygen saturation measurement. This paper presents description on PPG and its characteristic waveform and working principle. It also includes brief explanation on nonlinear analysis of PPG signals and salient applications of PPG followed by its advantages and limitations.