Absorption spectra of the oxygenated and deoxygenated hemoglobin molecules.
Notes: In the red and the infrared regions, the absorption is relatively low and allows accurate measurement of light transmission. Copyright © 1999. Prahl S. Reproduced from Prahl S. Optical absorption of hemoglobin. 1999. Available from: http://omlc.ogi.edu/spectra/hemoglobin/index.html. Accessed May 26, 2014.8
Abbreviations: HbO2, oxygenated hemoglobin; Hb, deoxygenated hemoglobin.

Absorption spectra of the oxygenated and deoxygenated hemoglobin molecules. Notes: In the red and the infrared regions, the absorption is relatively low and allows accurate measurement of light transmission. Copyright © 1999. Prahl S. Reproduced from Prahl S. Optical absorption of hemoglobin. 1999. Available from: http://omlc.ogi.edu/spectra/hemoglobin/index.html. Accessed May 26, 2014.8 Abbreviations: HbO2, oxygenated hemoglobin; Hb, deoxygenated hemoglobin.

Source publication
Article
Full-text available
Oxygen saturation in the arterial blood (SaO2) provides information on the adequacy of respiratory function. SaO2 can be assessed noninvasively by pulse oximetry, which is based on photoplethysmographic pulses in two wavelengths, generally in the red and infrared regions. The calibration of the measured photoplethysmographic signals is performed em...

Similar publications

Conference Paper
Full-text available
Sepsis, a critical bacterial infection of the bloodstream, is a serious cause of illness in the neonatal period in both premature and at term newborns. It is important to look for parameters that can help earlier detection of sepsis in the newborn. Previous studies have shown that Heart Rate Variability is reduced when associated with sepsis and di...

Citations

... Light-scattering spectroscopy (elastic scattering spectroscopy, fluorescence spectroscopy, Raman scattering spectroscopy, multimodal spectroscopy, etc.) [3], as a prerequisite for the development of these methods, is based on a qualitative or quantitative comparison of the received light flux distributions with the known scattering and/or absorption spectra of individual elements, compounds and substances. Biomedical photometry (for example, pulse oximetry and oxygen sensors [4], bilirubinometry [5], blood glucometry [6]), in turn, uses the results of spectroscopic studies and uses one or more wavelengths in the applied quantitative analysis [7,8], which allows monitoring of the physical or metabolic indicator level. At the same time, their ability to transmittance, reflectance and spatial light scattering is considered typical biological media optical properties. ...
Article
Full-text available
This paper analyzes the light-scattering standards currently used for calibration (verification) and systematic research in photo and spectrophotometry tools. The application specificities in studying the diffuse reflected and transmitted light during biomedical CCD photometry are considered. The advantages of a new class of photometers with non-spherical reflectors as ellipsoids of revolution truncated along the focal planes with the internal mirror surface are presented. The ellipsoid first focal plane is combined with the surface of the under-study media, and the second is optically coupled to the CCD image sensor plane. The principles of zone analysis of spatial distribution reproduced in photometric images on a CCD sensor are substantiated. The illuminance levels of photometric image areas in reflected and transmitted light from the thickness of the standard for the wavelength of laser radiation of 650 nm of different power was experimentally investigated. Polynomial dependences were obtained, and regression coefficients of the illuminance of the external and middle rings in photometric images for the reflected and transmitted light on the laser power were determined.
... Disponível em: https://www.scielo.br/j/ape/a/z7zZ4Z4GwYV6FR7S9FHTByr. Acesso em: 08 set., 2022.SABINO, K. A. Análise da Psicopatia no âmbito da violência contra a mulher.2021, 30f. ...
... This technique is widely used in the medical field for monitoring patients' oxygen levels, especially in critical care settings. To calibrate the measured photoplethysmographic signals for each type of commercial pulseoximeter sensor, an empirical approach is employed, which involves in vitro measurement of SpO2 in extracted arterial blood through co-oximetry [5]. By utilizing Artificial Neural Networks (ANN) or Machine Learning models, it is possible to rapidly and accurately predict SpO2 from a single-channel PPG signal, thus overcoming the limitations imposed by the traditional R-value based calibration method utilized in signal processing methods [6]. ...
Conference Paper
Full-text available
In this study, data was extracted from the Physionet MIMIC-III clinical database, which contained diverse medical records of patients who were admitted to the critical care units of Beth Israel Deaconess Medical Center between 2001 and 2012. Our research focused on PPG signals and SpO2 values, which were subjected to preprocessing and filtering in Python. The processed PPG data, together with the corresponding SpO2 values, were categorized based on the interval of SpO2 signal measurement, i.e., either one second or one minute. Subsequently, the filtered data was stored on a private ownCloud server, where it will be employed to enhance the database and facilitate the development of deep learning models for SpO2 prediction from one-channel PPG signals. At present, 340 GB of filtered data has been stored, which corresponds to approximately 2100 patients.
... Image-based classification is used to detect sore throats [25]. Transmissive pulse oximetry [26] is used to detect SpO2. Oxygen-based sensors are used to detect shortness of breath [27]. ...
Article
Full-text available
p>In this research work, coronavirus disease (COVID-19) has been considered to help mankind survive the present-day pandemic. This research is helpful to monitor the patients newly infected by the virus, and patients who have already recovered from the disease, and also to study the flow of virus from similar health issues. In this paper, an Internet of things (IoT) framework has been developed for the early detection of suspected cases. This framework is used for collecting and uploading symptoms (data) through sensor devices to the physician, data analytics center, cloud, and isolation/health centers. The symptoms of the first wave, second wave, and omicron are used to identify the suspects. Five machine learning algorithms which are considered to be the best in the existing literature have been used to find the best machine learning classifier in this research work. The proposed framework is used for the rapid detection of COVID-19 cases from real-world COVID-19 symptoms to mitigate the spread in society. This model also monitors the affected patient who has undergone treatment and recovered. It also collects data for analysis to perform further improvements in algorithms based on daily updated information from patients to provide better solutions to mankind.</p
... This sets the basis for the working principle of a pulse oximeter, which measures the difference in light intensities caused by the unique absorbance characteristics of oxygenated and deoxygenated hemoglobin at different wavelengths. 51,59 More specifically, oxygenated (deoxygenated) hemoglobin lets more red (infrared) light pass through while absorbing more infrared (red) light [ Fig. 7(a)]. Therefore, a basic pulse oximeter requires only three components at its core: a red light source operating at $660 nm (R), an infrared light source operating at $940 nm (IR), and a photodetector (PD) [ Fig. 7(b)]. ...
... This method of noninvasively measuring peripheral SpO 2 levels in a controlled clinical environment has been shown to be within 3%-4% (2%-3% for continuous monitoring) accuracy of the more accurate, invasive arterial SpO 2 measurements. 59 The level of accuracy achieved is considered to be sufficient for most cases; however, more accurate methods may be required for oxygenation monitoring of critically ill patients and newborn infants due to the fact that the calibration curves for pulse oximetry are generally derived from healthy individuals of higher ages. Consequently, noninvasive medical grade pulse oximeters alone generally do not provide decisive readings and hence are often used in combination with other monitoring systems to improve diagnostics in clinical settings, especially for COVID-19 patients. ...
Article
Full-text available
The COVID-19 pandemic has changed the lives of many people around the world. Based on the available data and published reports, most people diagnosed with COVID-19 exhibit no or mild symptoms and could be discharged home for self-isolation. Considering that a substantial portion of them will progress to a severe disease requiring hospitalization and medical management, including respiratory and circulatory support in the form of supplemental oxygen therapy, mechanical ventilation, vasopressors, etc. The continuous monitoring of patient conditions at home for patients with COVID-19 will allow early determination of disease severity and medical intervention to reduce morbidity and mortality. In addition, this will allow early and safe hospital discharge and free hospital beds for patients who are in need of admission. In this review, we focus on the recent developments in next-generation wearable sensors capable of continuous monitoring of disease symptoms, particularly those associated with COVID-19. These include wearable non/minimally invasive biophysical (temperature, respiratory rate, oxygen saturation, heart rate, and heart rate variability) and biochemical (cytokines, cortisol, and electrolytes) sensors, sensor data analytics, and machine learning-enabled early detection and medical intervention techniques. Together, we aim to inspire the future development of wearable sensors integrated with data analytics, which serve as a foundation for disease diagnostics, health monitoring and predictions, and medical interventions.
... It uses light-emitting diodes at the green, red, or infrared wavelengths and an arrangement of photodetectors to measure (through transmission or reflection) small variations in light intensity due to volumetric oscillations in perfusion of that tissue [21], [22]. In practice, this method has been successfully adopted in hospitals and clinics via fingertip pulse oximeters to obtain blood oxygen saturation and heart rate [23], [24]. Nevertheless, because PPG and continuous BP morphologies are strongly correlated (r > 0.9) [25], and the cardiovascular system ultimately generates both waves, there is a relative consensus in the literature that the former can also carry information about the latter. ...
Article
Full-text available
Cardiovascular diseases are the leading causes of death, and blood pressure (BP) monitoring is essential for prevention, diagnosis, assessment, and treatment. Photoplethysmography (PPG) is a low-cost opto-electronic technique for BP measurement that allows the acquisition of a modulated light signal highly correlated with BP. There are several reports of methods to estimate BP from PPG with impressive results; in this study, we demonstrate that the previous results are excessively optimistic because of their train/test split configuration. To manage this limitation, we considered intra- and inter-subject data arrangements and demonstrated how they affect the results of feature-based BP estimation algorithms (i.e., XGBoost, LightGBM, and CatBoost) and signal-based algorithms (i.e., Residual U-Net, ResNet-18, and ResNet-LSTM). Inter-subject configuration performance is inferior to intra-subject configuration performance, regardless of the model. We also showed that, using only demographic attributes (i.e., age, sex, weight, and subject index number), a regression model achieved results comparable to those obtained in an intra-subject scenario.Although limited to a public clinical database, our findings suggest that algorithms that use an intra-subject setting without a calibration strategy may be learning to identify patients and not predict BP.
... It uses light-emitting diodes at the green, red, or infrared wavelengths and an arrangement of photodetectors to measure (through transmission or reflection) small variations in light intensity due to volumetric oscillations in perfusion of that tissue [21], [22]. In practice, this method has been successfully adopted in hospitals and clinics via fingertip pulse oximeters to obtain blood oxygen saturation and heart rate [23], [24]. Nevertheless, because PPG and continuous BP morphologies are strongly correlated (r > 0.9) [25], and the cardiovascular system ultimately generates both waves, there is a relative consensus in the literature that the former can also carry information about the latter. ...
Preprint
Full-text available
p>Cardiovascular diseases are the leading causes of death in humans, and blood pressure (BP) monitoring is an important procedure to prevent, diagnose, assess, and treat these diseases, thereby avoiding more severe conditions. The most reliable and common techniques of measuring BP use sphygmomanometers, but they are more suited to single measurements than continuous ones. A more promising approach is the use of photoplethysmography (PPG), a low-cost, opto-electronic technique that, in the form of wearable devices, allows the acquisition of a modulated light signal highly correlated to BP. In this context, many works have reported methods to estimate BP from PPG, achieving impressive results. In order to prevent overestimation of these results, we investigate---by considering two different data arrangements---how intra- and inter-subject variabilities in BP can affect the results of machine learning algorithms. We also compare the outcomes of these algorithms with the outcome of a regression using age, sex, weight and subject index number as attributes. Our general conclusion is that those algorithms might actually be learning to identify persons instead of predicting BP, showing that the split of data is a very important step.</p
... It is a parameter we must closely monitor in many patients as a direct indicator of oxygen supply to the organs and tissues. SaO2 level can be determined noninvasively by pulse oximetry; this measurement, defined as peripheral oxygen saturation SpO 2 , has been reported to provide an accurate result with a standard deviation (SD) of 2% compared with the invasive method [1]. As a rational and easily applicable method, pulse oximetry is widely used in clinical practice for monitoring heart rate (HR) and SpO 2 . ...
Article
Background: Authors widely use pulse oximetry in clinical monitoring of heart rate (HR) and peripheral oxygen saturation (SpO2) by attachment to the fingers; however, there can be a need for an alternative attachment site, especially for burned patients. We investigate the availability of a pulse oximeter probe attached to the penile shaft as an alternative site in pediatric male patients if all extremities became unavailable for pulse oximetry measurement due to severe burn and/or trauma. Methods: We designed a prospective comparative study in a training and research hospital. After local ethical committee approval, pediatric male cases eligible for penile and extremity pulse measurements were evaluated during general anesthesia for medical dressing and/or grafting due to severe burns. One probe was attached to the fingers of the unburned extremity, and the other was to the penile shaft. Furthermore, we recorded SpO2and HR values at 5-min intervals; 0th (baseline), 5th, 10th and 15th minutes. We compared HR and SpO2values measured by the finger probe with those measured by the penile probe. Results: Data of 51 patients (median age, 2.9 years (interquartile range, 2.0-5.0 years)) in whom the duration of dressing was at least 15min were analyzed. There was no significant difference either in comparisons of hemodynamic measurements (HR and SpO2 ) obtainedby finger probe and by a penile probe for each measurement time. The Bland-Altman plot analysis reveals agreement for penile and finger probes with a mean bias value between 0.20 and 0.37 on HR and between 0.43 and -0.20 on SpO2. Discussion: This clinical trial demonstrated that pulse oximetry measurement under nonhypoxic conditions we could perform confidently using penile probes in pediatric male patients whose extremities are unavailable for measurement.
... index finger), which were anatomically far removed from the location of the EMI intervention. However, the measurement method applied in the current study was well suited for recording systemic influences on the microcirculation or, as in the present case, for excluding them (47,48). Peripheral non-invasive transcutaneous measurements of oxygen saturation and tissue perfusion are used for the early assessment of the peripheral effects of central organ functions or external influencing factors (47,48). ...
... However, the measurement method applied in the current study was well suited for recording systemic influences on the microcirculation or, as in the present case, for excluding them (47,48). Peripheral non-invasive transcutaneous measurements of oxygen saturation and tissue perfusion are used for the early assessment of the peripheral effects of central organ functions or external influencing factors (47,48). ...
Article
Full-text available
Objective: To evaluate the effects of high-energy pulsed electromagnetic fields on unspecific back pain. Methods: A prospective, randomized, sham-controlled clinical trial with repeated measurements was performed. The study included 5 visits (V0 to V4) with 3 interventions during V1, V2 and V3. Sixty-one patients aged between 18 and 80 years with unspecific back pain (acute inflammatory diseases and specific causes were reasons for exclusion) were included. The treatment group (n = 31) received 1–2 pulses/s, with an intensity of 50 mT, and an electric field strength of at least 20 V/m on 3 consecutive weekdays for 10 min each time. The control group (n = 30) received a comparable sham therapy. Pain intensity (visual analogue scale), local oxyhaemoglobin saturation, heart rate, blood pressure, and perfusion index were evaluated before (b) and after (a) V1 and V3 interventions. Change in visual analogue scale for V1 (ChangeV1a-b) and V3 (ChangeV3a-b), and ChangeData between V3a and V1b (ChangeV3a–V1b) for the remaining data were calculated (results were mean (standard deviation) (95% confidence interval; 95% CI)). Results: Concerning the visual analogue scale: (i) compared with the control group, the treatment group had higher ChangeV1a–b (–1.25 (1.76) (95% CI –1.91 to –0.59) vs –2.69 (1.74) (95% CI –3.33 to –2.06), respectively), and comparable Change V3a–b (–0.86 (1.34) (95% CI –1.36 to –0.36) vs –1.37 (1.03) (95% CI –1.75 to 0.99), respectively); and (ii) there was a significant marked decrease in Change V3a–1b in the treatment group compared with the control group (–5.15 (1.56) (95% CI –5.72 to –4.57) vs –2.58 (1.68) (95% CI –3.21 to –1.96), p = 0.001, respectively). There was no significant ChangeV3a–V1b in local oxyhaemoglobin saturation, heart rate, blood pressure or perfusion index between the 2 groups and for the same group (before vs after). Conclusion: Non-thermal, non-invasive electromagnetic induction therapy had a significant and rapid influence on unspecific back pain in the treatment group. LAY ABSTRACT Back pain is a health disorder of outstanding epidemiological, medical, and health economic importance. In the case of unspecific back pain, there is no clear specific cause. Electrotherapy is a physical therapy procedure using electric current for therapeutic purposes. Electromagnetic induction can influence many biological processes that are important for therapeutic interventions. A relatively new method is the use of non-invasive, very short, high-energy pulsed electromagnetic fields. Based on the literature, observations, and guidelines available up to February 2023, therapeutically successful use of electromagnetic induction appears possible, particularly in the case of high-energy pulsed electromagnetic fields. Pulsed electromagnetic fields with high-energy pulsed electromagnetic fields are therefore the logical therapeutic extension of high-energy pulsed electromagnetic fields. This study was designed to test the theory that high-energy pulsed electromagnetic fields can reduce unspecific back-pain. The application of electromagnetic induction, short high-frequency and high-energy, but non-thermal, electromagnetic pulses with a magnetic flux density of approximately 50–100 mT was found to reduce unspecific back-pain in the treatment area of the treatment group.
... These conditions can lead to low oxygenation levels that pose a potentially life-threatening risk. While oxygen saturation (SaO 2 ) values can be extracted invasively by means of arterial blood gas test, the method based on PPG relies on the distinct response of oxygenated and deoxygenated hemoglobin to different wavelengths and typically yields values only slightly different from SaO 2 [10,22,23]. ...
Article
Full-text available
The increasing interest in innovative solutions for health and physiological monitoring has recently fostered the development of smaller biomedical devices. These devices are capable of recording an increasingly large number of biosignals simultaneously, while maximizing the user’s comfort. In this study, we have designed and realized a novel wearable multisensor ring-shaped probe that enables synchronous, real-time acquisition of photoplethysmographic (PPG) and galvanic skin response (GSR) signals. The device integrates both the PPG and GSR sensors onto a single probe that can be easily placed on the finger, thereby minimizing the device footprint and overall size. The system enables the extraction of various physiological indices, including heart rate (HR) and its variability, oxygen saturation (SpO2), and GSR levels, as well as their dynamic changes over time, to facilitate the detection of different physiological states, e.g., rest and stress. After a preliminary SpO2 calibration procedure, measurements have been carried out in laboratory on healthy subjects to demonstrate the feasibility of using our system to detect rapid changes in HR, skin conductance, and SpO2 across various physiological conditions (i.e., rest, sudden stress-like situation and breath holding). The early findings encourage the use of the device in daily-life conditions for real-time monitoring of different physiological states.