Performance of popular pulse oximeters compared with simultaneous arterial oxygen saturation or clinical-grade pulse oximetry: a cross-sectional validation study in intensive care patients

Melanometry for objective evaluation of skin pigmentation in pulse oximetry studies

Pulse oximetry enables real-time, noninvasive monitoring of arterial blood oxygen levels. However, results can vary with skin color, thus detecting disparities during clinical validation studies requires an accurate measure of skin pigmentation. Recent clinical studies have used subjective methods such as self-reported color, race/ethnicity to categorize skin. Melanometers based on optical reflectance may offer a more effective, objective approach to assess pigmentation. Here, we review melanometry approaches and assess evidence supporting their use as clinical research tools. We compare performance data, including repeatability, robustness to confounders, and compare devices to each other, to subjective methods, and high-quality references. Finally, we propose best practices for evaluating melanometers and discuss alternate optical approaches that may improve accuracy. Whilst evidence indicates that melanometers can provide superior performance to subjective approaches, we encourage additional research and standardization efforts, as these are needed to ensure consistent and reliable results in clinical studies.

An innovative method to prevent infection when measuring the arterial blood gas SpO2 saturation

Background

Patients are hospitalized for extended periods, particularly in intensive care units (ICUs). As a result, the saturation probe (pulse oximeter) remains attached for an extended period and microorganisms can grow in the wet environment. If the pulse oximeters are not reprocessed, cross-infection may occur. The literature contains several studies in which gloves were used for the measurement while various SpO2 (peripheral arterial oxygen saturation) measurements were compared with each other. However, such comparisons have yet to be made with the results of arterial blood gas SpO2 measurements by pulse oximeter, considered as the gold standard. The present study aimed to compare arterial blood gas values with the fingertip saturation measurement performed by having adult patients wear gloves of different colors, one after the other, on their fingers and determining the effect of the differently colored gloves (transparent, white, black, light blue) on saturation values.

Methods

The study was conducted on 54 patients in an ICU. Intra-arterial blood gas SpO2 results were measured. Oxygen saturation was measured while the patient 1. did not wear gloves and 2. sequentially wore a series of gloves of different colors. Paired t-test, correlation analysis, and Bland Altman charts were used to evaluate the results.

Results

The mean SpO2% value of the participants' intra-arterial blood gas measurements was 97.76±2.04. The mean SpO2% value obtained from the measurements of the fingers with a transparent glove was 0.43 points lower than the mean SpO2% value of the intra-arterial blood gas measurements (t=0.986, p=0.61). The mean SpO2% value obtained from the measurements of the fingers with a white glove was 0.93 points lower than the mean SpO2% value of the intra-arterial blood gas measurements (t=1.157, p=0.093).

Conclusion

Of the measurements performed with a glove, the mean SpO2% value obtained from the measurements of the fingers with a transparent glove was more consistent with the mean SpO2% value of the intra-arterial blood gas measurements than measurement of the fingers without a glove.

A gender specific risk assessment of coronary heart disease based on physical examination data

Large-scale screening for the risk of coronary heart disease (CHD) is crucial for its prevention and management. Physical examination data has the advantages of wide coverage, large capacity, and easy collection. Therefore, here we report a gender-specific cascading system for risk assessment of CHD based on physical examination data. The dataset consists of 39,538 CHD patients and 640,465 healthy individuals from the Luzhou Health Commission in Sichuan, China. Fifty physical examination characteristics were considered, and after feature screening, ten risk factors were identified. To facilitate large-scale CHD risk screening, a CHD risk model was developed using a fully connected network (FCN). For males, the model achieves AUCs of 0.8671 and 0.8659, respectively on the independent test set and the external validation set. For females, the AUCs of the model are 0.8991 and 0.9006, respectively on the independent test set and the external validation set. Furthermore, to enhance the convenience and flexibility of the model in clinical and real-life scenarios, we established a CHD risk scorecard base on logistic regression (LR). The results show that, for both males and females, the AUCs of the scorecard on the independent test set and the external verification set are only slightly lower (<0.05) than those of the corresponding prediction model, indicating that the scorecard construction does not result in a significant loss of information. To promote CHD personal lifestyle management, an online CHD risk assessment system has been established, which can be freely accessed at http://lin-group.cn/server/CHD/index.html .

Personal protective equipment-induced systemic hypercapnic hypoxaemia: translational implications for impaired cognitive-clinical functional performance

BACKGROUND

Personal protective equipment (PPE) adversely affects pulmonary gas exchange and may result in systemic hypercapnic hypoxaemia and headache. This study aimed to determine what extent PPE affects cerebral symptoms, global cerebral blood flow, and cognitive functional performance.

METHODS

Higher surgical trainees participated in a randomized, repeated-measures, crossover study, completing 60 min of laparoscopic surgical simulation in both standard operating attire and type 3 PPE. Measurements were collected at baseline and after 60 min of simulation. The primary outcome measure was headache. Headache was examined using the validated visual analogue scale (VAS) and Environmental Symptoms Questionnaire C (ESQ-C), global cerebral blood flow with duplex ultrasonography, and visuospatial and executive gross/fine motor function with grooved peg board (GPB) and laparoscopic bead (LSB) board tasks.

RESULTS

Thirty-one higher surgical trainees (20 men, 11 women) completed the study. Compared with standard operating attire, PPE increased headache assessment scores (mean(s.d.) VAS score 3.5(5.6) versus 13.0(3.7), P < 0.001; ESQ-C score 1.3(2.0) versus 5.9(5.1), P < 0.001) and was associated with poorer completion times for GPB-D (61.4(12.0) versus 71.1(12.4) s; P = 0.034) and LSB (192.5(66.9) versus 270.7(135.3) s; P = 0.025) tasks. Wearing PPE increased heart rate (82.5(13.6) versus 93.5(13.0) beats/min; P = 0.022) and skin temperature (36.6(0.4) versus 37.1(0.5)°C; P < 0.001), but decreased peripheral oxygen saturation (97.9(0.8) versus 96.8(1.0) per cent; P < 0.001). Female higher surgical trainees exhibited higher peripheral oxygen saturation across all conditions. No differences were observed in global cerebral blood flow as a function of attire, time or sex.

CONCLUSION

Despite no marked changes in global cerebral blood flow, type 3 PPE was associated with increased headache scores and cerebral symptoms (VAS and ESQ-C) alongside impaired executive motor function highlighting the clinical implications of PPE-induced impairment for cognitive-clinical performance.

The accuracy of pulse oximetry in measuring oxygen saturation by levels of skin pigmentation: a systematic review and meta-analysis

BACKGROUND

During the COVID-19 pandemic, there have been concerns regarding potential bias in pulse oximetry measurements for people with high levels of skin pigmentation. We systematically reviewed the effects of skin pigmentation on the accuracy of oxygen saturation measurement by pulse oximetry (SpO2) compared with the gold standard SaO2 measured by CO-oximetry.

METHODS

We searched Ovid MEDLINE, Ovid Embase, EBSCO CINAHL, ClinicalTrials.gov, and WHO International Clinical Trials Registry Platform (up to December 2021) for studies with SpO2-SaO2 comparisons and measuring the impact of skin pigmentation or ethnicity on pulse oximetry accuracy. We performed meta-analyses for mean bias (the primary outcome in this review) and its standard deviations (SDs) across studies included for each subgroup of skin pigmentation and ethnicity and used these pooled mean biases and SDs to calculate accuracy root-mean-square (Arms) and 95% limits of agreement. The review was registered with the Open Science Framework ( https://osf.io/gm7ty ).

RESULTS

We included 32 studies (6505 participants): 15 measured skin pigmentation and 22 referred to ethnicity. Compared with standard SaO2 measurement, pulse oximetry probably overestimates oxygen saturation in people with the high level of skin pigmentation (pooled mean bias 1.11%; 95% confidence interval 0.29 to 1.93%) and people described as Black/African American (1.52%; 0.95 to 2.09%) (moderate- and low-certainty evidence). The bias of pulse oximetry measurements for people with other levels of skin pigmentation or those from other ethnic groups is either more uncertain or suggests no overestimation. Whilst the extent of mean bias is small or negligible for all subgroups evaluated, the associated imprecision is unacceptably large (pooled SDs > 1%). When the extent of measurement bias and precision is considered jointly, pulse oximetry measurements for all the subgroups appear acceptably accurate (with Arms < 4%).

CONCLUSIONS

Pulse oximetry may overestimate oxygen saturation in people with high levels of skin pigmentation and people whose ethnicity is reported as Black/African American, compared with SaO2. The extent of overestimation may be small in hospital settings but unknown in community settings. REVIEW PROTOCOL REGISTRATION: https://osf.io/gm7ty.

Remote care and triage of obstetric patients with COVID-19 in the community: operational considerations

Background

During the SARS-CoV-2 (COVID-19) pandemic, routine antenatal care was disrupted, and pregnant women positive for COVID-19 were at increased risk of caesarean section, intensive care admission or neonatal unit admission for their baby. Virtual care and telehealth can reduce barriers to care and improve maternity outcomes, and adoption has been encouraged by health authorities in the United Kingdom.

Methods

Norfolk and Norwich University Hospitals Trust deployed a flexible maternity virtual ward (MVW) service using the Current Health platform to care for pregnant women during the pandemic. Patients were monitored either intermittently with finger pulse oximetry or continuously with a wearable device. We outline the MVW technology, intervention and staffing model, triage criteria and patient feedback, as an example of an operational model for other institutions.

Results

Between October 2021 and February 2022, 429 patients were referred, of which 228 were admitted to the MVW. Total bed-days was 1,182, mean length of stay was 6 days (SD 2.3, range 1–14 days). Fifteen (6.6%) required hospital admission and one (0.4%) critical care. There were no deaths. Feedback alluded to feelings of increased safety, comfort, and ease with the technology.

Conclusions

The MVW offered a safety net to pregnant women positive for COVID-19. It provided reassurance for staff, while relieving pressures on infrastructure. When setting up similar services in future, attention should be given to identifying clinical champions, triage criteria, technology and alarm selection, and establishing flexible escalation pathways that can adapt to changing patterns of disease.

Evaluation of a New Smartphone Powered Low-cost Pulse Oximeter Device

Background

Measurement of blood oxygen saturation is a vital part of monitoring coronavirus 2019 (COVID-19) patients. Pulse oximetry is commonly used to measure blood oxygen saturation and pulse rate for appropriate clinical intervention. But the majority of direct-to-consumer grade pulse oximeters did not pass through in-vivo testing, which results in their accuracy being questionable. Besides this, the ongoing COVID-19 pandemic exposed the limitations of the device in resource limited areas since independent monitoring is needed for COVID-19 patients. The purpose of this study was to perform an in-vivo evaluation of a newly developed smartphone powered low-cost pulse oximeter.

Methods

The new prototype of a smartphone powered pulse oximeter was evaluated against the standard pulse oximeter by taking measurements from fifteen healthy volunteers. The accuracy of measurement was evaluated by calculating the percentage error and standard deviation. A repeatability and reproducibility test were carried out using the ANOVA method.

Results

The average accuracy for measuring spot oxygen saturation (SPO2) and pulse rate (PR) was 99.18% with a standard deviation of 0.57 and 98.78% with a standard deviation of 0.61, respectively, when compared with the standard pulse oximeter device. The repeatability and reproducibility of SPO2 measurements were 0.28 and 0.86, respectively, which is in the acceptable range.

Conclusion

The new prototype of smartphone powered pulse oximeter demonstrated better performance compared to the existing low-cost fingertip pulse oximeters. The device could be used for independent monitoring of COVID-19 patients at health institutions and also for home care.

Feasibility of screening for critical congenital heart disease using pulse oximetry in Indonesia

BACKGROUND

Screening of critical congenital heart disease (CCHD) using pulse oximetry is a routine procedure in many countries, but not in Indonesia. This study aimed to evaluate the feasibility of implementing CCHD screening with pulse oximetry for newborns in Yogyakarta, Indonesia.

METHODS

A cross-sectional study was conducted at four hospitals in Yogyakarta, Indonesia. Newborns aged 24-48 hours who met the inclusion criteria were screened on the right hand and left or right foot using a pulse oximeter. Positive results were indicated by: either (1) SpO2 level < 90% in one extremity, (2) SpO2 level of 90-94% in both right hand and either foot on three measurements conducted 1 hour apart, or (3) a saturation difference > 3% between the upper and lower extremity on three measurements conducted 1 hour apart. Positive findings were confirmed by echocardiography.

RESULTS

Of 1452 newborns eligible for screening, 10 had positive results and were referred for echocardiographic evaluation. Of those, 8 (6 per 1000 live birth, 8/1452) had CCHD. Barriers found during screening processes were associated with hospital procedures, equipment, healthcare personnel, and condition of the newborn.

CONCLUSION

Pulse oximetry screening might be feasible to be implemented within the routine newborn care setting for CCHD in Indonesia. In order to successfully implement pulse oximetry screening to identify CCHD in Indonesia, the barriers will need to be addressed.

Skin Pigmentation Influence on Pulse Oximetry Accuracy: A Systematic Review and Bibliometric Analysis

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.