-
British Journal of Anaesthesia Jan 2023Recent reports highlight potential inaccuracies of pulse oximetry in patients with various degrees of skin pigmentation. We summarise the literature, provide an overview...
Recent reports highlight potential inaccuracies of pulse oximetry in patients with various degrees of skin pigmentation. We summarise the literature, provide an overview of potential clinical implications, and provide insights into how pulse oximetry could be improved to mitigate against such potential shortcomings.
Topics: Humans; Skin Pigmentation; Oximetry; Oxygen
PubMed: 35430087
DOI: 10.1016/j.bja.2022.03.011 -
Pediatric Critical Care Medicine : a... Jun 2023Pulse oximetry (Sp o2 ) may overestimate arterial oxygen saturation (Sa o2 ) in blood laboratory testing. This study aimed to assess Sp o2 -Sa o2 difference in relation...
OBJECTIVES
Pulse oximetry (Sp o2 ) may overestimate arterial oxygen saturation (Sa o2 ) in blood laboratory testing. This study aimed to assess Sp o2 -Sa o2 difference in relation to race (i.e., patient self-reporting as Black or White), occult hypoxemia, and length of stay (LOS) in pediatric patients with COVID-19.
DESIGN
Single-center retrospective study in pediatric COVID-19 patients. We used multivariable linear regressions to examine the association between race and oximetry measurements and between occult hypoxemia and LOS. Oximetry bias was defined using Sp o2 and Sa o2 data according to approved comparisons. Occult hypoxemia was defined as Sp o2 greater than 92% and Sa o2 less than 88%.
SETTING
Quaternary pediatric hospital.
PATIENTS
Pediatric COVID-19 patients admitted to Texas Children's Hospital between May 2020 and December 2021.
INTERVENTIONS
None.
MEASUREMENTS AND MAIN RESULTS
There were 2713 patients with complete physiological data in the analysis. Of the total, 61% were Black, and 39% were White. Oximetry bias was greater in Black compared with White patients ( p < 0.001), and this bias increased as the oxygen saturations decreased ( p < 0.001). Black and White patients had a 12% and 4% prevalence of occult hypoxemia, respectively ( p < 0.001). LOS was not associated with oximetry bias or occult hypoxemia once controlled for the level of support (intensive care, respiratory, circulatory).
CONCLUSIONS
We found an oximetry bias in the measurement of Sp o2 with respect to Sa o2 in symptomatic hospitalized pediatric patients with the diagnosis of COVID-19. Furthermore, race is related to an increased oximetry bias. However, we did not find a relationship between oximetry bias and the LOS in the hospital in this cohort of patients.
Topics: Humans; Child; Retrospective Studies; Oxygen; COVID-19; Oximetry; Hypoxia
PubMed: 36825900
DOI: 10.1097/PCC.0000000000003208 -
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 -
Respiratory Care Dec 2022
Topics: Humans; Retrospective Studies; Oximetry; Oxygen
PubMed: 36442988
DOI: 10.4187/respcare.10654 -
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 -
Neonatology 2021Even a few minutes of exposure to oxygen in the delivery room in very preterm and immature infants may have detrimental effects. The initial oxygenation in the delivery... (Review)
Review
Even a few minutes of exposure to oxygen in the delivery room in very preterm and immature infants may have detrimental effects. The initial oxygenation in the delivery room should therefore be optimized, but knowledge gaps, including initial fraction of oxygen (FiO2) and how FiO2 should be changed to reach an optimal oxygen saturation measured by pulse oximetry (SpO2) target within the first 5-10 min of life, remain. In order to answer this question, we therefore reviewed relevant literature. For newly born infants with gestational age (GA) <32 weeks in need of positive pressure ventilation (PPV) immediately after birth, we identified 2 fundamental issues: (1) the optimal initial FiO2 and (2) the target SpO2 within the first 5-10 min of life. For newly born infants between 29 and 31 weeks of GA, an initial FiO2 of 0.3 hit the target defined by the International Liaison Committee on Resuscitation (ILCOR) best. Newborn infants with GA <29 weeks in need of PPV and supplementary oxygen, we suggest starting with FiO2 0.3 and adjusting the FiO2 to reach SpO2 of 80% within 5 min of life for best outcomes. Prolonged bradycardia (heart rate <100 bpm for >2 min) is associated with increased risk of adverse outcomes, including death. The combination of strict control of development of SpO2 in the first 10 min of life and a heart rate >100 bpm represents the best tool today to achieve the most optimal outcome in the delivery room of very preterm and immature newborn infants.
Topics: Gestational Age; Humans; Infant; Infant, Newborn; Infant, Premature; Infant, Premature, Diseases; Oximetry; Oxygen
PubMed: 33902059
DOI: 10.1159/000516261 -
Ceska a Slovenska Oftalmologie :... 2020To inform about possible use of the automatic retinal oximetry for the retinal oxygen saturation measurement in the eye and systemic diseases. (Review)
Review
PURPOSE
To inform about possible use of the automatic retinal oximetry for the retinal oxygen saturation measurement in the eye and systemic diseases.
METHODS
We performed a literature review dealing with issues of retinal oxygen saturation monitoring by dual non-invasive retinal oximetry Oxymap T1 (Oxymap ehf. Reykjavík, Iceland).
RESULTS
We have found two main strains writing our paper on retinal oxygen saturation eye diseases. The first section concerns diseases created by having hypoxia as its main pathological factor - for example diabetes mellitus and retinal vein occlusion. The second group deals with atrophy as the main pathological mechanism which is typical for decreasing retinal oxygen consumption - for example glaucoma or retinitis pigmentosa (the second one named is not included in our work). Oximetry in systemic diseases creates a relatively new chapter of this branch with a very big potential of interdisciplinary cooperation for the future. It is possible the cooperation will not only include diabetologists but also neurologists (for example, in diseases like sclerosis multiplex or Devics, Alzheimers and Parkinsons disease) and haematologists (retinal oxygen saturation changes in patients with different rheological attributes of blood).
CONCLUSION
Retinal oxygen saturation measuring by automatic retinal oximetry is a relatively new method with scientifically confirmed high reproducibility of results. Currently it is the only experimental method with vast potentials not only in the realm of the possibility of observing eye diseases (diabetic retinopathy, retinal vein occlusion or glaucoma) but also in developing interdisciplinary cooperation with diabetologists, neurologists and haematologists.
Topics: Humans; Oximetry; Oxygen; Reproducibility of Results; Retina; Retinal Vessels
PubMed: 32917089
DOI: 10.31348/2020/1 -
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