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Pachyn E, Aumiller M, Freymüller C, Linek M, Volgger V, Buchner A, Rühm A, Sroka R. Investigation on the influence of the skin tone on hyperspectral imaging for free flap surgery. Sci Rep 2024; 14:13979. [PMID: 38886457 PMCID: PMC11183063 DOI: 10.1038/s41598-024-64549-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 06/10/2024] [Indexed: 06/20/2024] Open
Abstract
Hyperspectral imaging (HSI) is a new emerging modality useful for the noncontact assessment of free flap perfusion. This measurement technique relies on the optical properties within the tissue. Since the optical properties of hemoglobin (Hb) and melanin overlap, the results of the perfusion assessment and other tissue-specific parameters are likely to be distorted by the melanin, especially at higher melanin concentrations. Many spectroscopic devices have been shown to struggle with a melanin related bias, which results in a clinical need to improve non-invasive perfusion assessment, especially for a more pigmented population. This study investigated the influence of skin tones on tissue indices measurements using HSI. In addition, other factors that might affect HSI, such as age, body mass index (BMI), sex or smoking habits, were also considered. Therefore, a prospective feasibility study was conducted, including 101 volunteers from whom tissue indices measurements were performed on 16 different body sites. Skin tone classification was performed using the Fitzpatrick skin type classification questionnaire, and the individual typology angle (ITA) acquired from the RGB images was calculated simultaneously with the measurements. Tissue indices provided by the used HSI-device were correlated to the possible influencing factors. The results show that a dark skin tone and, therefore, higher levels of pigmentation influence the HSI-derived tissue indices. In addition, possible physiological factors influencing the HSI-measurements were found. In conclusion, the HSI-based tissue indices can be used for perfusion assessment for people with lighter skin tone levels but show limitations in people with darker skin tones. Furthermore, it could be used for a more individual perfusion assessment if different physiological influencing factors are respected.
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Affiliation(s)
- Ester Pachyn
- Department of Urology, Laser-Forschungslabor, LIFE Center, University Hospital, LMU Munich, Fraunhoferstrasse 20, 82152, Planegg, Germany.
| | - Maximilian Aumiller
- Department of Urology, Laser-Forschungslabor, LIFE Center, University Hospital, LMU Munich, Fraunhoferstrasse 20, 82152, Planegg, Germany
- Department of Urology, University Hospital, LMU Munich, 81377, Munich, Germany
| | - Christian Freymüller
- Department of Urology, Laser-Forschungslabor, LIFE Center, University Hospital, LMU Munich, Fraunhoferstrasse 20, 82152, Planegg, Germany
- Department of Urology, University Hospital, LMU Munich, 81377, Munich, Germany
| | - Matthäus Linek
- Department of Urology, Laser-Forschungslabor, LIFE Center, University Hospital, LMU Munich, Fraunhoferstrasse 20, 82152, Planegg, Germany
| | - Veronika Volgger
- Department of Otorhinolaryngology, University Hospital, LMU Munich, 81377, Munich, Germany
| | - Alexander Buchner
- Department of Urology, University Hospital, LMU Munich, 81377, Munich, Germany
| | - Adrian Rühm
- Department of Urology, Laser-Forschungslabor, LIFE Center, University Hospital, LMU Munich, Fraunhoferstrasse 20, 82152, Planegg, Germany
- Department of Urology, University Hospital, LMU Munich, 81377, Munich, Germany
| | - Ronald Sroka
- Department of Urology, Laser-Forschungslabor, LIFE Center, University Hospital, LMU Munich, Fraunhoferstrasse 20, 82152, Planegg, Germany
- Department of Urology, University Hospital, LMU Munich, 81377, Munich, Germany
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Haxha S, Nwibor C, Ali M, Sakel M, Saunders K, Dyo V, Nabakooza S. Effect of Skin Pigmentation and Finger Choice on Accuracy of Oxygen Saturation Measurement in an IoT-Based Pulse Oximeter. SENSORS (BASEL, SWITZERLAND) 2024; 24:3301. [PMID: 38894093 PMCID: PMC11174708 DOI: 10.3390/s24113301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 05/14/2024] [Accepted: 05/18/2024] [Indexed: 06/21/2024]
Abstract
Pulse oximeters are widely used in hospitals and homes for measurement of blood oxygen saturation level (SpO2) and heart rate (HR). Concern has been raised regarding a possible bias in obtaining pulse oximeter measurements from different fingertips and the potential effect of skin pigmentation (white, brown, and dark). In this study, we obtained 600 SpO2 measurements from 20 volunteers using three UK NHS-approved commercial pulse oximeters alongside our custom-developed sensor, and used the Munsell colour system (5YR and 7.5YR cards) to classify the participants' skin pigmentation into three distinct categories (white, brown, and dark). The statistical analysis using ANOVA post hoc tests (Bonferroni correction), a Bland-Altman plot, and a correlation test were then carried out to determine if there was clinical significance in measuring the SpO2 from different fingertips and to highlight if skin pigmentation affects the accuracy of SpO2 measurement. The results indicate that although the three commercial pulse oximeters had different means and standard deviations, these differences had no clinical significance.
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Affiliation(s)
- Shyqyri Haxha
- Department of Electronic Engineering, Royal Holloway, University of London, Egham TW20 0EX, UK; (C.N.); (M.A.); (V.D.)
| | - Chike Nwibor
- Department of Electronic Engineering, Royal Holloway, University of London, Egham TW20 0EX, UK; (C.N.); (M.A.); (V.D.)
| | - Mian Ali
- Department of Electronic Engineering, Royal Holloway, University of London, Egham TW20 0EX, UK; (C.N.); (M.A.); (V.D.)
| | - Mohamed Sakel
- East Kent Hospitals University NHS Foundation Trust, Canterbury CT2 7NT, UK; (M.S.); (K.S.)
| | - Karen Saunders
- East Kent Hospitals University NHS Foundation Trust, Canterbury CT2 7NT, UK; (M.S.); (K.S.)
| | - Vladimir Dyo
- Department of Electronic Engineering, Royal Holloway, University of London, Egham TW20 0EX, UK; (C.N.); (M.A.); (V.D.)
| | - Shakira Nabakooza
- Hertfordshire Partnership University NHS Foundation Trust, Hatfield, St. Albans AL3 5TQ, UK;
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Hao S, Dempsey K, Matos J, Cox CE, Rotemberg V, Gichoya JW, Kibbe W, Hong C, Wong I. Utility of skin tone on pulse oximetry in critically ill patients: a prospective cohort study. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.02.24.24303291. [PMID: 38464170 PMCID: PMC10925348 DOI: 10.1101/2024.02.24.24303291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Importance Pulse oximetry, a ubiquitous vital sign in modern medicine, has inequitable accuracy that disproportionately affects Black and Hispanic patients, with associated increases in mortality, organ dysfunction, and oxygen therapy. Although the root cause of these clinical performance discrepancies is believed to be skin tone, previous retrospective studies used self-reported race or ethnicity as a surrogate for skin tone. Objective To determine the utility of objectively measured skin tone in explaining pulse oximetry discrepancies. Design Setting and Participants Admitted hospital patients at Duke University Hospital were eligible for this prospective cohort study if they had pulse oximetry recorded up to 5 minutes prior to arterial blood gas (ABG) measurements. Skin tone was measured across sixteen body locations using administered visual scales (Fitzpatrick Skin Type, Monk Skin Tone, and Von Luschan), reflectance colorimetry (Delfin SkinColorCatch [L*, individual typology angle {ITA}, Melanin Index {MI}]), and reflectance spectrophotometry (Konica Minolta CM-700D [L*], Variable Spectro 1 [L*]). Main Outcomes and Measures Mean directional bias, variability of bias, and accuracy root mean square (ARMS), comparing pulse oximetry and ABG measurements. Linear mixed-effects models were fitted to estimate mean directional bias while accounting for clinical confounders. Results 128 patients (57 Black, 56 White) with 521 ABG-pulse oximetry pairs were recruited, none with hidden hypoxemia. Skin tone data was prospectively collected using 6 measurement methods, generating 8 measurements. The collected skin tone measurements were shown to yield differences among each other and overlap with self-reported racial groups, suggesting that skin tone could potentially provide information beyond self-reported race. Among the eight skin tone measurements in this study, and compared to self-reported race, the Monk Scale had the best relationship with differences in pulse oximetry bias (point estimate: -2.40%; 95% CI: -4.32%, -0.48%; p=0.01) when comparing patients with lighter and dark skin tones. Conclusions and relevance We found clinical performance differences in pulse oximetry, especially in darker skin tones. Additional studies are needed to determine the relative contributions of skin tone measures and other potential factors on pulse oximetry discrepancies.
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Affiliation(s)
- Sicheng Hao
- Duke University, Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Durham, NC, USA
| | - Katelyn Dempsey
- Duke University, Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Durham, NC, USA
| | - João Matos
- Duke University, Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Durham, NC, USA
| | - Christopher E. Cox
- Duke University, Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Durham, NC, USA
| | | | - Judy W. Gichoya
- Emory University School of Medicine, Department of Radiology, Atlanta, USA
| | - Warren Kibbe
- Duke University, Department of Biostatistics and Bioinformatics, Division of Translational Biomedical Informatics, Durham, NC, USA
| | - Chuan Hong
- Duke University, Department of Biostatistics and Bioinformatics, Division of Translational Biomedical Informatics, Durham, NC, USA
| | - Ian Wong
- Duke University, Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Durham, NC, USA
- Duke University, Department of Biostatistics and Bioinformatics, Division of Translational Biomedical Informatics, Durham, NC, USA
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Else TR, Hacker L, Gröhl J, Bunce EV, Tao R, Bohndiek SE. Effects of skin tone on photoacoustic imaging and oximetry. JOURNAL OF BIOMEDICAL OPTICS 2024; 29:S11506. [PMID: 38125716 PMCID: PMC10732256 DOI: 10.1117/1.jbo.29.s1.s11506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 11/02/2023] [Accepted: 11/28/2023] [Indexed: 12/23/2023]
Abstract
Significance Photoacoustic imaging (PAI) provides contrast based on the concentration of optical absorbers in tissue, enabling the assessment of functional physiological parameters such as blood oxygen saturation (sO 2 ). Recent evidence suggests that variation in melanin levels in the epidermis leads to measurement biases in optical technologies, which could potentially limit the application of these biomarkers in diverse populations. Aim To examine the effects of skin melanin pigmentation on PAI and oximetry. Approach We evaluated the effects of skin tone in PAI using a computational skin model, two-layer melanin-containing tissue-mimicking phantoms, and mice of a consistent genetic background with varying pigmentations. The computational skin model was validated by simulating the diffuse reflectance spectrum using the adding-doubling method, allowing us to assign our simulation parameters to approximate Fitzpatrick skin types. Monte Carlo simulations and acoustic simulations were run to obtain idealized photoacoustic images of our skin model. Photoacoustic images of the phantoms and mice were acquired using a commercial instrument. Reconstructed images were processed with linear spectral unmixing to estimate blood oxygenation. Linear unmixing results were compared with a learned unmixing approach based on gradient-boosted regression. Results Our computational skin model was consistent with representative literature for in vivo skin reflectance measurements. We observed consistent spectral coloring effects across all model systems, with an overestimation of sO 2 and more image artifacts observed with increasing melanin concentration. The learned unmixing approach reduced the measurement bias, but predictions made at lower blood sO 2 still suffered from a skin tone-dependent effect. Conclusion PAI demonstrates measurement bias, including an overestimation of blood sO 2 , in higher Fitzpatrick skin types. Future research should aim to characterize this effect in humans to ensure equitable application of the technology.
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Affiliation(s)
- Thomas R. Else
- University of Cambridge, CRUK Cambridge Institute, Cambridge, United Kingdom
- University of Cambridge, Department of Physics, Cambridge, United Kingdom
| | - Lina Hacker
- University of Cambridge, CRUK Cambridge Institute, Cambridge, United Kingdom
- University of Cambridge, Department of Physics, Cambridge, United Kingdom
| | - Janek Gröhl
- University of Cambridge, CRUK Cambridge Institute, Cambridge, United Kingdom
- University of Cambridge, Department of Physics, Cambridge, United Kingdom
| | - Ellie V. Bunce
- University of Cambridge, CRUK Cambridge Institute, Cambridge, United Kingdom
- University of Cambridge, Department of Physics, Cambridge, United Kingdom
| | - Ran Tao
- University of Cambridge, CRUK Cambridge Institute, Cambridge, United Kingdom
- University of Cambridge, Department of Physics, Cambridge, United Kingdom
| | - Sarah E. Bohndiek
- University of Cambridge, CRUK Cambridge Institute, Cambridge, United Kingdom
- University of Cambridge, Department of Physics, Cambridge, United Kingdom
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Cabanas AM, Martín-Escudero P, Shelley KH. Improving pulse oximetry accuracy in dark-skinned patients: technical aspects and current regulations. Br J Anaesth 2023; 131:640-644. [PMID: 37544838 DOI: 10.1016/j.bja.2023.07.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 06/15/2023] [Accepted: 07/08/2023] [Indexed: 08/08/2023] Open
Abstract
Recent concerns regarding the clinical accuracy of pulse oximetry in dark-skinned patients, specifically in detecting occult hypoxaemia, have motivated research on this topic and recently reported in this journal. We provide an overview of the technical aspects of the issue, the sources of inaccuracy, and the current regulations and limitations. These insights offer perspectives on how pulse oximetry can be improved to address these potential limitations.
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Affiliation(s)
- Ana M Cabanas
- Department of Physics, Universidad de Tarapacá, Arica, Chile.
| | - Pilar Martín-Escudero
- Medical School of Sport Medicine, Faculty of Medicine, Universidad Complutense de Madrid, Madrid, Spain
| | - Kirk H Shelley
- Department of Anesthesiology, Yale University, New Haven, CT, USA
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Patterson S, Sandercock N, Verhovsek M. Understanding pulse oximetry in hematology patients: Hemoglobinopathies, racial differences, and beyond. Am J Hematol 2022; 97:1659-1663. [PMID: 36074079 DOI: 10.1002/ajh.26721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/27/2022] [Accepted: 08/30/2022] [Indexed: 01/31/2023]
Abstract
Pulse oximetry (SpO2 ) is a widely used, non-invasive method of estimating arterial oxygen saturation. Measurement of SpO2 relies on comparing the relative absorption of light in the red and infrared regions with the expected absorption pattern of oxygenated and deoxygenation adult hemoglobin. As this screening tool has entered common clinical use, test limitations have emerged, including concern about the risk of overestimation of oxygen saturation by pulse oximetry in a disproportionate number of people with dark skin pigment, leading to potential for underdiagnosis of true hypoxemia. In addition, a range of challenges may arise in patients with increased levels of methemoglobin - whether acquired or inherited - carboxyhemoglobin, or in patients with a subset of inherited variant hemoglobins. It is important for Hematologists, and indeed all clinicians who rely on pulse oximetry, to understand the principles and limitations of this ubiquitous test.
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Affiliation(s)
- Sarah Patterson
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Nick Sandercock
- Molecular Hematology, Hamilton Health Sciences, Hamilton, Ontario, Canada
| | - Madeleine Verhovsek
- Division of Hematology and Thromboembolism, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
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Cabanas AM, Fuentes-Guajardo M, Latorre K, León D, Martín-Escudero P. Skin Pigmentation Influence on Pulse Oximetry Accuracy: A Systematic Review and Bibliometric Analysis. SENSORS (BASEL, SWITZERLAND) 2022; 22:3402. [PMID: 35591092 PMCID: PMC9102088 DOI: 10.3390/s22093402] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 04/15/2022] [Accepted: 04/20/2022] [Indexed: 02/04/2023]
Abstract
Nowadays, pulse oximetry has become the standard in primary and intensive care units, especially as a triage tool during the current COVID-19 pandemic. Hence, a deeper understanding of the measurement errors that can affect precise readings is a key element in clinical decision-making. Several factors may influence the accuracy of pulse oximetry, such as skin color, body temperature, altitude, or patient movement. The skin pigmentation effect on pulse oximetry accuracy has long been studied reporting some contradictory conclusions. Recent studies have shown a positive bias in oxygen saturation measurements in patients with darkly pigmented skin, particularly under low saturation conditions. This review aims to study the literature that assesses the influence of skin pigmentation on the accuracy of these devices. We employed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement to conduct a systematic review retrospectively since February 2022 using WOS, PubMed, and Scopus databases. We found 99 unique references, of which only 41 satisfied the established inclusion criteria. A bibliometric and scientometrics approach was performed to examine the outcomes of an exhaustive survey of the thematic content and trending topics.
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Affiliation(s)
- Ana M. Cabanas
- Departamento de Física, Universidad de Tarapacá, Arica 1010069, Chile
| | | | - Katina Latorre
- Departamento de Tecnología Médica, Universidad de Tarapacá, Arica 1010069, Chile; (M.F.-G.); (K.L.)
| | - Dayneri León
- Departamento de Educación Física, Universidad de Tarapacá, Arica 1010069, Chile;
| | - Pilar Martín-Escudero
- Medical School of Sport Medicine, Faculty of Medicine, Universidad Complutense de Madrid, 28040 Madrid, Spain;
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