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Journal of Biomedical Optics Oct 2020The arterial carbon dioxide (CO2) partial pressure PaCO2 is a clinically relevant variable. However, its measurement requires arterial blood sampling or bulky and...
SIGNIFICANCE
The arterial carbon dioxide (CO2) partial pressure PaCO2 is a clinically relevant variable. However, its measurement requires arterial blood sampling or bulky and expensive transcutaneous PtcCO2 meters. While the spectrophotometric determination of hemoglobin species-such as oxy-hemoglobin (O2Hb) and deoxy-hemoglobin (HHb)-allowed for the development of pulse oximetry, the measurement of CO2 blood content with minimal discomfort has not been addressed yet.
AIM
Characterizing human carbamino-hemoglobin (CO2Hb) absorption spectrum, which is missing from the literature. Providing the theoretical background that will allow for transcutaneous, noninvasive PaCO2 measurements.
APPROACH
A tonometry-based approach was used to obtain gas-equilibrated, lysed, diluted human blood. Equilibration was performed with both CO2, dinitrogen (N2), and ambient air. Spectrophotometric measurements were carried out on the 235- to 1000-nm range. A theoretical background was also derived from that of pulse oximetry.
RESULTS
The absorption spectra of both CO2Hb and HHb were extremely close and comparable with that of state-of-the-art HHb. The above-mentioned theoretical background led to an estimated relative error above 30% on the measured amount of CO2Hb in a subject's blood. Auxiliary measurements revealed that the use of ethylene diamine tetraacetic acid did not interfere with spectrophotometric measurements, whereas sodium metabisulfite did.
CONCLUSIONS
CO2Hb absorption spectrum was measured for the first time. Such spectrum being close to that of HHb, the use of a theoretical background based on pulse oximetry theory for noninvasive PaCO2 measurement seems extremely challenging.
Topics: Blood Gas Monitoring, Transcutaneous; Carbon Dioxide; Humans; Oximetry; Oxyhemoglobins; Partial Pressure
PubMed: 33098280
DOI: 10.1117/1.JBO.25.10.105001 -
Trials Oct 2023The SafeBoosC project aims to test the clinical value of non-invasive cerebral oximetry by near-infrared spectroscopy in newborn infants. The purpose is to establish...
BACKGROUND
The SafeBoosC project aims to test the clinical value of non-invasive cerebral oximetry by near-infrared spectroscopy in newborn infants. The purpose is to establish whether cerebral oximetry can be used to save newborn infants' lives and brains or not. Newborns contribute heavily to total childhood mortality and neonatal brain damage is the cause of a large part of handicaps such as cerebral palsy. The objective of the SafeBoosC-IIIv trial is to evaluate the benefits and harms of cerebral oximetry added to usual care versus usual care in mechanically ventilated newborns.
METHODS/DESIGN
SafeBoosC-IIIv is an investigator-initiated, multinational, randomised, pragmatic phase-III clinical trial. The inclusion criteria will be newborns with a gestational age more than 28 + 0 weeks, postnatal age less than 28 days, predicted to require mechanical ventilation for at least 24 h, and prior informed consent from the parents or deferred consent or absence of opt-out. The exclusion criteria will be no available cerebral oximeter, suspicion of or confirmed brain injury or disorder, or congenital heart disease likely to require surgery. A total of 3000 participants will be randomised in 60 neonatal intensive care units from 16 countries, in a 1:1 allocation ratio to cerebral oximetry versus usual care. Participants in the cerebral oximetry group will undergo cerebral oximetry monitoring during mechanical ventilation in the neonatal intensive care unit for as long as deemed useful by the treating physician or until 28 days of life. The participants in the cerebral oximetry group will be treated according to the SafeBoosC treatment guideline. Participants in the usual care group will not receive cerebral oximetry and will receive usual care. We use two co-primary outcomes: (1) a composite of death from any cause or moderate to severe neurodevelopmental disability at 2 years of corrected age and (2) the non-verbal cognitive score of the Parent Report of Children's Abilities-Revised (PARCA-R) at 2 years of corrected age.
DISCUSSION
There is need for a randomised clinical trial to evaluate cerebral oximetry added to usual care versus usual care in mechanically ventilated newborns.
TRIAL REGISTRATION
The protocol is registered at www.
CLINICALTRIALS
gov (NCT05907317; registered 18 June 2023).
Topics: Infant; Child; Infant, Newborn; Humans; Oximetry; Respiration, Artificial; Cerebrovascular Circulation; Brain; Intensive Care Units, Neonatal; Randomized Controlled Trials as Topic
PubMed: 37898759
DOI: 10.1186/s13063-023-07699-x -
Physiological Measurement Jun 2023. Pulse oximetry is a non-invasive optical technique used to measure arterial oxygen saturation (SpO) in a variety of clinical settings and scenarios. Despite being one... (Review)
Review
. Pulse oximetry is a non-invasive optical technique used to measure arterial oxygen saturation (SpO) in a variety of clinical settings and scenarios. Despite being one the most significant technological advances in health monitoring over the last few decades, there have been reports on its various limitations. Recently due to the Covid-19 pandemic, questions about pulse oximeter technology and its accuracy when used in people with different skin pigmentation have resurfaced, and are to be addressed.. This review presents an introduction to the technique of pulse oximetry including its basic principle of operation, technology, and limitations, with a more in depth focus on skin pigmentation. Relevant literature relating to the performance and accuracy of pulse oximeters in populations with different skin pigmentation are evaluated.. The majority of the evidence suggests that the accuracy of pulse oximetry differs in subjects of different skin pigmentations to a level that requires particular attention, with decreased accuracy in patients with dark skin.. Some recommendations, both from the literature and contributions from the authors, suggest how future work could address these inaccuracies to potentially improve clinical outcomes. These include the objective quantification of skin pigmentation to replace currently used qualitative methods, and computational modelling for predicting calibration algorithms based on skin colour.
Topics: Humans; Skin Pigmentation; Pandemics; COVID-19; Oximetry; Oxygen
PubMed: 37172609
DOI: 10.1088/1361-6579/acd51a -
Journal of the American Veterinary... Nov 2022To evaluate the accuracy for 2 smartwatches with oximetry technology and optical wrist heart rate (HR) or single-lead Electrocardiography (ECG) technology (Fenix 5X Plus...
Two different smartwatches exhibit high accuracy in evaluating heart rate and peripheral oxygen saturation in cats when compared with the electrocardiography and transmittance pulse oximetry.
OBJECTIVE
To evaluate the accuracy for 2 smartwatches with oximetry technology and optical wrist heart rate (HR) or single-lead Electrocardiography (ECG) technology (Fenix 5X Plus [GF5xp], Garmin Ltd and Apple Watch 6 [AppW6], Apple Inc, respectively) versus reference methods (ECG and transmittance pulse oximetry [TPO], respectively) in measuring HR and peripheral oxygen saturation of hemoglobin (SpO2) in cats.
ANIMALS
10 male client-owned cats aged 8 to 12 months and weighing 3.2 to 4.5 kg.
PROCEDURES
All cats that were presented for elective castration at the Atatürk University Animal Hospital between March 10 and April 15, 2022, were considered for enrollment. Monitoring of HR and SpO2 during anesthesia was performed with a 3-lead ECG and transmittance pulse oximetry, respectively, connected to a multiparameter monitor (reference methods) along with a GF5xp and a AppW6. Agreement between reference methods and the smartwatches were assessed by the Bland-Altman plot, in which the differences (%) between methods were plotted against their mean HR or SpO2 (reference method measurement - test device measurement) and the limits of agreement (mean ± 1.96 × SD).
RESULTS
Compared with ECG measurements of HR, GF5xp had superior bias (-0.1%) and limit of agreement (LoA, 3.0 to -3.3%) versus those of the AppW6 (bias, 0.2%; LoA, 3.7 to -3.4%). Compared with TPO measurements of SpO2, AppW6 had superior bias (0.2%) and LoA (3.0% and -2.5%) versus those of the GF5xp (bias, -2.1%; LoA, 0.2 to -4.4%).
CLINICAL RELEVANCE
Results indicated that the GF5xp and AppW6 exhibited high accuracy in evaluating HR and SpO2 in cats when compared with the reference methods. However, it should be noted that these comparisons were made in anesthetized patients without any systemic disease.
Topics: Male; Cats; Animals; Oxygen Saturation; Oxygen; Heart Rate; Oximetry; Electrocardiography
PubMed: 36322488
DOI: 10.2460/javma.22.08.0357 -
Journal of Perinatology : Official... Jan 2015Randomized controlled trials evaluating low-target oxygen saturation (SpO2:85% to 89%) vs high-target SpO2 (91% to 95%) have shown variable results regarding mortality... (Review)
Review
Randomized controlled trials evaluating low-target oxygen saturation (SpO2:85% to 89%) vs high-target SpO2 (91% to 95%) have shown variable results regarding mortality and morbidity in extremely preterm infants. Because of the variation inherent to the accuracy of pulse oximeters, the unspecified location of probe placement, the intrinsic relationship between SpO2 and arterial oxygen saturation (SaO2) and between SaO2 and partial pressure of oxygen (PaO2) (differences in oxygen dissociation curves for fetal and adult hemoglobin), the two comparison groups could have been more similar than dissimilar. The SpO2 values were in the target range for a shorter period of time than intended due to practical and methodological constraints. So the studies did not truly compare 'target SpO2 ranges'. In spite of this overlap, some of the studies did find significant differences in mortality prior to discharge, necrotizing enterocolitis and severe retinopathy of prematurity. These differences could potentially be secondary to time spent beyond the target range (SpO2 <85 or >95%) and could be avoided with an intermediate but wider target SpO2 range (87% to 93%). In conclusion, significant uncertainty persists about the desired target range of SpO2 in extremely preterm infants. Further studies should focus on studying newer methods of assessing oxygenation and strategies to limit hypoxemia (<85% SpO2) and hyperoxemia (>95% SpO2).
Topics: Humans; Infant, Extremely Low Birth Weight; Infant, Newborn; Oximetry; Oxygen; Oxygen Inhalation Therapy; Randomized Controlled Trials as Topic; Software
PubMed: 25357098
DOI: 10.1038/jp.2014.199 -
Journal of Postgraduate Medicine 2015Obstructive sleep apnea (OSA) is a common but underdiagnosed sleep disorder, which is associated with systemic consequences such as hypertension, stroke, metabolic... (Review)
Review
Obstructive sleep apnea (OSA) is a common but underdiagnosed sleep disorder, which is associated with systemic consequences such as hypertension, stroke, metabolic syndrome, and ischemic heart disease. Nocturnal laboratory-based polysomnography (PSG) is the gold standard test for diagnosis of OSA. PSG consists of a simultaneous recording of multiple physiologic parameters related to sleep and wakefulness including electroencephalography (EEG), electrooculography (EOG), surface electromyography (EMG), airflow measurement using thermistor and nasal pressure transducer, pulse oximetry and respiratory effort (thoracic and abdominal). Multiple alternative and simpler methods that record respiratory parameters alone for diagnosing OSA have been developed in the past two decades. These devices are called portable monitors (PMs) and enable performing sleep studies at a lower cost with shorter waiting times. It has been observed and reported that comprehensive sleep evaluation coupled with the use of PMs can fulfill the unmet need for diagnostic testing in various out-of-hospital settings in patients with suspected OSA. This article reviews the available medical literature on PMs in order to justify the utility of PMs in the diagnosis of OSA, especially in resource-poor, high-disease burden settings. The published practice parameters for the use of these devices have also been reviewed with respect to their relevance in the Indian setting.
Topics: Electroencephalography; Humans; Monitoring, Ambulatory; Oximetry; Polysomnography; Practice Guidelines as Topic; Sleep Apnea, Obstructive
PubMed: 26440391
DOI: 10.4103/0022-3859.166509 -
Critical Care Medicine Oct 2020Capillary refill time is a noninvasive method to assess tissue perfusion to determine shock status. Capillary refill time is defined as the time required to regain skin... (Observational Study)
Observational Study
OBJECTIVES
Capillary refill time is a noninvasive method to assess tissue perfusion to determine shock status. Capillary refill time is defined as the time required to regain skin color after blanching pressure is applied. Although common methods to measure capillary refill time depend on clinicians' visual assessment, a new approach using a pulse oximeter waveform analysis exists, referred to as full finger reperfusion time. We aim to evaluate reproducibility and validity of the novel full finger reperfusion time measurement using clinicians' visual capillary refill time assessment as a reference standard.
DESIGN
Prospective observational study.
SETTING
PICUs and operating suites at a large academic children's hospital.
PATIENTS
Ninety-nine children 1-12 years old with various skin color tones.
INTERVENTIONS
Each child had 10 measurements, including five full finger reperfusion time and five clinician capillary refill time, alternating second and third digits.
MEASUREMENTS AND MAIN RESULTS
Eighteen children had prolonged capillary refill time (> 2 s) and four children with capillary refill time greater than 3 seconds. Four-hundred eighty-five data pairs were analyzed. Intraclass correlation coefficient of full finger reperfusion time within each patient was 0.76 (95% CI, 0.68-0.83), demonstrating good reproducibility. Correlation coefficient between full finger reperfusion time and clinician capillary refill time was moderate: r = 0.37 (p < 0.0001; 95% CI, 0.29-0.44) for the pairs and r = 0.52 (p < 0.0001; 95% CI, 0.36-0.65) for patient average. Bland-Altman plot showed a consistent difference between full finger reperfusion time and clinician capillary refill time (full finger reperfusion time 1.14 s longer). Weak association was found between force and full finger reperfusion time (β = -0.033 ± 0.016; 95% CI, -0.065 to -0.0016; p = 0.04), finger thickness (β = -0.20 ± 0.089; 95% CI, -0.37 to -0.19; p = 0.03), except for color tone (p = 0.31). Finger temperature was associated with full finger reperfusion time (β = -0.18 ± 0.041; 95% CI, -0.26 to -0.0999; p < 0.0001).
CONCLUSIONS
Full finger reperfusion time demonstrated good reproducibility. Full finger reperfusion time showed moderate correlation with clinician capillary refill time. Full finger reperfusion time was 1.14 seconds longer than capillary refill time. Future studies should focus on the clinical value of full finger reperfusion time as a monitoring device for hemodynamics in critically ill children.
Topics: Child; Child, Preschool; Female; Fingers; Hemodynamics; Hospitals, Pediatric; Humans; Infant; Intensive Care Units, Pediatric; Male; Oximetry; Prospective Studies; Reproducibility of Results; Shock; Skin
PubMed: 32701550
DOI: 10.1097/CCM.0000000000004506 -
Noninvasive Non-Contact SpO Monitoring Using an Integrated Polarization-Sensing CMOS Imaging Sensor.Sensors (Basel, Switzerland) Oct 2022In the diagnosis and primary health care of an individual, estimation of the pulse rate and blood oxygen saturation (SpO2) is critical. The pulse rate and SpO2 are...
BACKGROUND
In the diagnosis and primary health care of an individual, estimation of the pulse rate and blood oxygen saturation (SpO2) is critical. The pulse rate and SpO2 are determined by methods including photoplethysmography (iPPG), light spectroscopy, and pulse oximetry. These devices need to be compact, non-contact, and noninvasive for real-time health monitoring. Reflection-based iPPG is becoming popular as it allows non-contact estimation of the heart rate and SpO2. Most iPPG methods capture temporal data and form complex computations, and thus real-time measurements and spatial visualization are difficult.
METHOD
In this research work, reflective mode polarized imaging-based iPPG is proposed. For polarization imaging, a custom image sensor with wire grid polarizers on each pixel is designed. Each pixel has a wire grid of varying transmission axes, allowing phase detection of the incoming light. The phase information of the backscattered light from the fingertips of 12 healthy volunteers was recorded in both the resting as well as the excited states. These data were then processed using MATLAB 2021b software.
RESULTS
The phase information provides quantitative information on the reflection from the superficial and deep layers of skin. The ratio of deep to superficial layer backscattered phase information is shown to be directly correlated and linearly increasing with an increase in the SpO2 and heart rate.
CONCLUSIONS
The phase-based measurements help to monitor the changes in the resting and excited state heart rate and SpO2 in real time. Furthermore, the use of the ratio of phase information helps to make the measurements independent of the individual skin traits and thus increases the accuracy of the measurements. The proposed iPPG works in ambient light, relaxing the instrumentation requirement and helping the system to be compact and portable.
Topics: Humans; Oximetry; Photoplethysmography; Monitoring, Physiologic; Heart Rate; Fingers; Oxygen
PubMed: 36298147
DOI: 10.3390/s22207796 -
Sensors (Basel, Switzerland) May 2022The purpose of this research was to develop an algorithm for a wearable device that would prevent people from drowning in swimming pools. The device should detect...
The purpose of this research was to develop an algorithm for a wearable device that would prevent people from drowning in swimming pools. The device should detect pre-drowning symptoms and alert the rescue staff. The proposed detection method is based on analyzing real-time data collected from a set of sensors, including a pulse oximeter. The pulse oximetry technique is used for measuring the heart rate and oxygen saturation in the subject's blood. It is an optical method; subsequently, the measurements obtained this way are highly sensitive to interference from the subject's motion. To eliminate noise caused by the subject's movement, accelerometer data were used in the system. If the acceleration sensor does not detect movement, a biosensor is activated, and an analysis of selected physiological parameters is performed. Such a setup of the algorithm allows the device to distinguish situations in which the person rests and does not move from situations in which the examined person has lost consciousness and has begun to drown.
Topics: Drowning; Humans; Oximetry; Oxygen; Swimming Pools; Wearable Electronic Devices
PubMed: 35632232
DOI: 10.3390/s22103823 -
Archivos Argentinos de Pediatria Apr 2022Near infrared spectroscopy (NIRS) is a non-invasive optical technique for the evaluation of regional tissue oxygenation using transcutaneous detectors. In recent years,... (Review)
Review
Near infrared spectroscopy (NIRS) is a non-invasive optical technique for the evaluation of regional tissue oxygenation using transcutaneous detectors. In recent years, publications about this topic have increased exponentially; this reflects the growing interest among investigators and clinicians about this new technology and its potential benefits for pediatric patients. The objective of this review is to know the functioning and potential uses of regional saturation measured by NIRS and establish future challenges.
Topics: Child; Hemodynamic Monitoring; Humans; Oximetry; Oxygen; Pediatrics; Spectroscopy, Near-Infrared
PubMed: 35338818
DOI: 10.5546/aap.2022.eng.129