Oximetry Measurements Research Articles

A prospective study for an alternative probe site for pulse oximetry measurement in male patients with severe burn trauma: penile shaf.

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. 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. 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. 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.

O073 Traditional Clinical and Novel Oximetry Measures as Predictors of Cardiovascular Events

Abstract Introduction Intermittent hypoxia is a key mechanism linking Obstructive Sleep Apnoea (OSA) to cardiovascular disease (CVD). Oximetry analysis could enhance understanding of which OSA phenotypes are associated with CVD risk. We investigated if traditional clinical and novel oximetry measures including hypoxic burden (HB) calculated from the polysomnogram SpO2 signal can predict CVD outcomes in all-comers and OSA subsample cohorts from the Sleep Heart Health Study (SHHS). Methods CVD mortality outcome and complete covariate information was used. We implemented 31 oximetry measures and assessed the performance of the parameters in predicting CVD outcomes (CVD death or incident CVD) in the all-comers and sleep apnoea subsamples. The performance of each measure was assessed using an adjusted Cox proportional hazard ratio (HR) analysis. Results In the general subsample, HB successfully predicted CVD death (HR>1.8, p<0.05) but did not predict incident CVD. In the sleep apnoea subsample (AHI>5) with no CVD at baseline, none of the SpO2 measures we considered predicted incident CVD. Discussion The ability of HB to predict CVD outcomes depends on the cohort and the CVD outcome. Our analysis of the selected SpO2 measures in an OSA subsample did not find strong links between any oximetry measures and incident CVD, and therefore no strong candidates for CVD risk phenotyping in the sleep clinic. Further work is needed to understand the complex relationship between OSA-related intermittent hypoxia patterns and development of CVD to further understanding of OSA phenotypes at risk of CVD consequences.

Prospective analysis on carotid endarterectomy: intermediate-deep ultrasound-guided cervical blockade versus general anesthesia.

The best regional anesthesia plan with the best clinical results for Carotid endarterectomy (CEA) has not been defined yet. Prospective multicentric observational study of two non-randomized matched cohorts including patients undergoing elective unilateral CEA (N.=100) between January-October 2021. Main outcomes were cerebral oximetry measurements, verbal numeric pain score assessment, peripheral nerve blockades and in-hospital stay. The main objective is to compare results achieved after carotid endarterectomy (CEA) performed under loco-regional blockade (LRB) versus general anesthesia (GA), in terms of intraoperative hemodynamic and neurologic variability. Patients undergoing LRB were performed under ultrasound (US) guidance and mild sedation. The LRB and GA groups showed no differences in comorbidities and risk factors. However, there was a significant difference in the intraoperative hemodynamic behavior due to the amount of vasoactive drugs used (0% vs. 16% for phenylephrine, P=0.006). The results showed neurological stability through the cerebral oximetry measurements during the procedure except for the left hemisphere de-clamp values, which were higher in the GA group (68.7±9.9 vs. 72.7±8.8; P=0.035). There were also significant differences in the verbal pain scale scores assessed 6 hours and 12 hours after the procedure; better pain control was evidenced in the LRB group (0[0-1] vs. 1[0-3], P=0.01; 1[0.5-2] vs. 0[0-2], P=0.01). An increased transient hypoglossal and laryngeal nerves blockade was observed in the LRB group (30% vs. 4%; P<0.001). The in-hospital length of stay was longer in the GA group (77.2±36.3 hours vs. 129.1±41.1 hours; P<0.001). Although the use of intermediate-deep cervical plexus blockade for CEA confers similar neurologic stability as GA does, there is a difference on the hemodynamic behaviour due to the differences in vasoactive drug consumption. Loco-regional techniques provide a better postoperative pain control and shorten in-hospital length of stay.

Artifacts classification and apnea events detection in neck photoplethysmography signals

The novel pulse oximetry measurement site of the neck is a promising location for multi-modal physiological monitoring. Specifically, in the context of respiratory monitoring, in which it is important to have direct information about airflow. The neck makes this possible, in contrast to common photoplethysmography (PPG) sensing sites. However, this PPG signal is susceptible to artifacts that critically impair the signal quality. To fully exploit neck PPG for reliable physiological parameters extraction and apneas monitoring, this paper aims to develop two classification algorithms for artifacts and apnea detection. Features from the time, correlogram, and frequency domains were extracted. Two SVM classifiers with RBF kernels were trained for different window (W) lengths and thresholds (Thd) of corruption. For artifacts classification, the maximum performance was attained for the parameters combination of [W = 6s-Thd= 20%], with an average accuracy= 85.84%(ACC), sensitivity= 85.43%(SE) and specificity= 86.26%(SP). For apnea detection, the model [W = 10s-Thd= 50%] maximized all the performance metrics significantly (ACC= 88.25%, SE= 89.03%, SP= 87.42%). The findings of this proof of concept are significant for denoising novel neck PPG signals, and demonstrate, for the first time, that it is possible to promptly detect apnea events from neck PPG signals in an instantaneous manner. This could make a big impact in crucial real-time applications, like devices to prevent sudden-unexpected-death-in-epilepsy (SUDEP).

Pilot study: Utility of long-wave infrared thermography as a correlate to transcutaneous oximetry for candidates of hyperbaric oxygen therapy.

Hyperbaric oxygen (HBO2 ) has been used as an adjunctive treatment for the care of advanced non-healing diabetic foot ulcers (DFUs). A patient's in-chamber transcutaneous oximetry measurement (TCOM) is currently the most effective predictor for response to HBO2 therapy but still excludes close to one in four patients who would benefit out of treatment groups when used for patient selection. Improving selection tools and criteria could potentially help better demonstrate HBO2 therapy's efficacy for such patients. We sought to identify if long-wave infrared thermography (LWIT) measurements held any correlation with a patient's TCOM measurements and if LWIT could be used in a response prediction role for adjunctive HBO2 therapy. To investigate, 24 patients already receiving TCOM measurements were enrolled to simultaneously be imaged with LWIT. LWIT measurements were taken throughout each patient's therapeutic course whether they underwent only standard wound care or adjunctive HBO2 treatments. A significant correlation was found between in-chamber TCOM and post-HBO2 LWIT. There was also a significant difference in the post-HBO2 LWIT measurement from 1st treatment to 6 weeks or the last treatment recorded. These initial findings are important as they indicate a possible clinical use for LWIT in the selection process for patients for HBO2 therapy. Larger studies should be carried out to further articulate the clinical use of LWIT in this capacity.

Difference between morning and evening blood pressure at home and nocturnal hypoxia in the general practitioner-based J-HOP study.

The aim of this study was to determine the independent association of nocturnal hypoxia with morning minus evening home blood pressure (MEdif) in a cohort of outpatients with at least one cardiovascular risk. A total of 1053 participants underwent home blood pressure (BP) portable pulse oximetry measurements, and 147 (14%) had an MEdif ≥20 mmHg, where MEdif was defined as the difference between morning and evening home systolic BP. When participants were divided into quartiles according to the lowest oxygen saturation (SpO2) during the nighttime, those in the lowest quartile (range, 54-79%) were significantly more likely to have MEdif ≥20 mmHg than those in the top quartile (range, 89-97%) (adjusted odds ratio, 1.98; 95% confidence interval, 1.13-3.49). The present study revealed an association between lowest SpO2 during the nighttime and increased MEdif in a cohort of outpatients with at least one cardiovascular risk.

Enhanced neutrophil activity, but not neutrophil extracellular trap markers, is found in patients with symptomatic chronic peripheral arterial disease

Abstract Background/Introduction Neutrophil degranulation and neutrophil extracellular traps (NETs) are suggested to play a role in cardiovascular (CV) disease development [1]. Human studies showed that markers of NETs, are increased in patients with severe coronary atherosclerosis and predict risk of cardiac events [2]. The role of NETs in peripheral artery disease (PAD) has not been investigated. Purpose To measure circulating markers of neutrophil activity in patients with symptomatic PAD compared with matched healthy controls, evaluate their association with disease severity, and assess their prognostic value. Methods Multicenter, prospective case-control study. Circulating levels of polymorphonuclear neutrophil (PMN)-elastase, neutrophil gelatinase-associated lipocalin (NGAL), myeloperoxidase (MPO), and NETs-associated MPO-DNA complexes were measured in patients with symptomatic PAD and heathy controls. The former underwent comprehensive vascular evaluation including ankle-brachial index (ABI) calculation, transcutaneous oximetry measurement, constant-load treadmill test, 6-minute walking test, pulse wave velocity, and flow-mediated dilatation of the brachial artery. Six-month outcomes were: occurrence of major adverse CV (MACE) and limb events (MALE), ABI reduction ≥0.15, and 6-minute walking distance reduction ≥20 m. Results Overall, 110 participants were included, 66 had symptomatic PAD. Levels of all but one biomarker (MPO-DNA) were significantly higher in patients with PAD compared with healthy controls (Fig. 1). No significant correlation was found between biomarkers and vascular tests in patients with PAD. Baseline PMN-elastase (adjusted hazard ratio [HR]: 1.010; 95% CI: 1.000–1.020; p=0.040) and MPO (adjusted HR: 1.027; 95% CI: 1.004–1.051; p=0.019) were predictive of MACE and/or MALE at 6-month follow-up in patients with symptomatic PAD (Table 1). Conclusions Present data show enhanced neutrophil activity, but not NETs levels, in patients with symptomatic PAD compared to controls. Baseline PMN-elastase and MPO levels were associated with worst CV outcome in patients with chronic PAD. These data suggest a role of neutrophils in PAD development and severity that needs to be further elucidated. Funding Acknowledgement Type of funding sources: None.

Innovative technology to eliminate the racial bias in non-invasive, point-of-care (POC) haemoglobin and pulse oximetry measurements

There is a significant unmet clinical need for a reliable point-of-care (POC) estimation of the blood haemoglobin (Hb) method. Current available methods, notably pulse oximetry, have certain limitations related to...

Biomarker associations with insomnia and secondary sleep outcomes in persons with and without HIV in the POPPY-Sleep substudy: a cohort study.

We investigated associations between inflammatory profiles/clusters and sleep measures in people living with HIV and demographically-/lifestyle-similar HIV-negative controls in the Pharmacokinetic and clinical Observations in PeoPle over fiftY (POPPY)-Sleep substudy. Primary outcome was insomnia (Insomnia Severity Index [ISI]>15). Secondary sleep outcomes included 7-day actigraphy (e.g. mean/standard deviation of sleep duration/efficiency), overnight oximetry (e.g. oxygen desaturation index [ODI]) and patient-reported measures (Patient-Reported Outcomes Measurement Information System (PROMIS) sleep questionnaires). Participants were grouped using Principal Component Analysis of 31 biomarkers across several inflammatory pathways followed by cluster analysis. Between-cluster differences in baseline characteristics and sleep outcomes were assessed using Kruskal-Wallis/logistic regression/Chi-squared/Fisher's exact tests. Of the 465 participants included (74% people with HIV, median [interquartile range] age 54 [50-60] years), only 18% had insomnia and secondary sleep outcomes suggested generally good sleep (e.g. ODI 3.1/hr [1.5-6.4]). Three clusters with distinct inflammatory profiles were identified: "gut/immune activation" (n = 47), "neurovascular" (n = 209), and "reference" (relatively lower inflammation; n = 209). The "neurovascular" cluster included higher proportions of people with HIV, obesity (BMI>30 kg/m2), and previous cardiovascular disease, mental health disorder, and arthritis of knee/hip relative to the other two clusters. No clinically relevant between-cluster differences were observed in proportions with insomnia (17%, 18%, 20%) before (p = .76) or after (p = .75) adjustment for potential confounders. Few associations were observed among actigraphy, oximetry, and PROMIS measures. Although associations could exist with other sleep measures or biomarker types not assessed, our findings do not support a strong association between sleep and inflammation in people with HIV.

211.7: Is Pulse Oximetry a Good Screening Test for Hepatopulmonary Syndrome in Liver Transplant Candidates?

Background: Pulse oximetry with oxygen saturation (SpO2) ≤96% is recommended as a screening test to identify patients (pts) with severe hepatopulmonary syndrome (HPS) to be eligible for MELD exceptions. However, diagnosis of milder forms requires contrast-enhanced echocardiography (CE-TTE) and arterial blood gas (ABG). Goals: 1) To investigate the prevalence of intrapulmonary vascular dilatations (IPVD) and HPS in pts with cirrhosis evaluated for liver transplantation (OLT) and 2) To compare the results of SpO2 with ABG measurements. Methods: The study included 972 consecutive pts (2013-2021) who completed pre-OLT evaluation including CE-TTE, SpO2 and ABG. IPVD was defined as the appearance of microbubbles in the left heart within 3-5 cardiac cycles and HPS by an alveolar arterial O2 gradient ≥ 15 mm Hg or ≥ 20 if age > 64 and absence of pulmonary chronic diseases. HPS was considered as mild, moderate or severe according to PaO2 (>80, 60-80 and <60 respectively). Results: The prevalence of IPVD was 15.4% (150/972) and of HPS 7.8% (76/972). Age of pts with HPS was 47±3 years (57% males) and MELD-Na 17± 1.HCV, alcoholism and autoimmune hepatitis were the most frequent etiologies of cirrhosis (22% each). Among pts with HPS 59 (78%) were mild (PaO2 108 ±22), 13 (17%) moderate (73 ±4) and 4 severe (55.5±3). SpO2 was ≤96% in 26% (20/76), 15% in mild (9/59), 54% in moderate (8/13) and 100% in severe (4/4) HPS. Unexpectedly, of 20 pts with Spo2 ≤96% only 4 had PaO2 <60 mmHg. Conclusions: Universal testing with CE-TTE followed by ABG in patients with cirrhosis evaluated for OLT resulted in a lower prevalence than reported of HPS, most likely due to the preponderance of mild clinical forms with normal SpO2. Using the recommended cut-off value of Spo2 ≤96% we found a poor correlation between pulse oximetry and ABG measurement.

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

BackgroundDuring 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.MethodsWe 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).ResultsWe 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%).ConclusionsPulse 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 registrationhttps://osf.io/gm7ty

Transcutaneous Oximetry Does Not Reliably Predict Wound-healing Complications in Preoperatively Radiated Soft Tissue Sarcoma.

Surgical wound-healing complications after tumor resections in tissue that has been preoperatively radiated are a major clinical problem. Most studies have reported that complications occur in more than 30% of patients undergoing such resections in the lower extremity. There is currently no available method to predict which patients are likely to have a complication. Transcutaneous oximetry has been identified in preliminary studies as potentially useful, but the available evidence on its efficacy for this application thus far is inconclusive. (1) Does transcutaneous oximetry measurement below 25 mmHg at any location in the surgical wound bed predict a wound-healing complication? (2) Does recovery (increase) in transcutaneous oxygen measurement during the rest period between the end of radiation and the time of surgery protect against wound-healing complications? A prospective, multi-institution study was coordinated to measure skin oxygenation at three timepoints in patients undergoing surgery for a lower extremity soft tissue sarcoma after preoperative radiation. Between 2016 and 2020, the five participating centers treated 476 patients for lower extremity soft tissue sarcoma. Of those, we considered those with a first-time sarcoma treated with radiation before limb salvage surgery as potentially eligible. Based on that, 21% (98 of 476) were eligible; a further 12% (56 of 476) were excluded because they refused to participate or ultimately, they were treated with a flap, amputation, or skin graft. Another 1% (3 of 476) of patients were lost because of incomplete datasets or follow-up less than 6 months, leaving 8% (39 of 476) for analysis here. The mean patient age was 62 ± 14 years, 62% (24 of 39) of the group were men, and 18% (7 of 39) of patients smoked cigarettes; 87% (34 of 39) of tumors were intermediate/high grade, and the most common histologic subtype was undifferentiated pleomorphic sarcoma. In investigating complications, a cutoff of 25 mmHg was chosen based on a pilot investigation that identified this value. All patients were assessed for surgical wound-healing complications, which were defined as: those resulting in a return to the operating room, initiation of oral or IV antibiotics, intervention for seroma, or prolonged wound packing or dressing changes. To answer the first research question, we compared the proportion of patients who developed a wound-healing complication between those patients who had any reading below 25 mmHg (7 of 39) and those who did not (32 of 39). To answer the second question, we compared the group with stable or decreased skin oxygenation (22 of 37 patient measurements [two patients missed the immediate postoperative measurement]) to the group that had increased skin oxygen measurement (15 of 37 measurements) during the period between the end of radiation and the surgical procedure; again, the endpoint was the development of a wound-healing complication. This study was powered a priori to detect an unadjusted odds ratio for wound-healing complications as small as 0.71 for a five-unit (5 mmHg) increase in TcO 2 between the groups, with α set to 0.05, β set to 0.2, and a sample size of 40 patients. We found no difference in the odds of a wound-healing complication between patients whose transcutaneous oxygen measurements were greater than or equal to 25 mmHg at all timepoints compared with those who had one or more readings below that threshold (odds ratio 0.27 [95% confidence interval (CI) 0.05 to 1.63]; p = 0.15). There was no difference in the odds of a wound-healing complication between patients who had recovery of skin oxygenation between radiation and surgery and those who did not (OR 0.63 [95% CI 0.37 to 5.12]; p = 0.64). Transcutaneous oximetry cannot be considered a reliable test in isolation to predict wound-healing complications. This may be a function of the fact that transcutaneous oximetry samples a relatively small portion of the landscape in which a wound-healing complication could potentially arise. In the absence of a reliable diagnostic test, clinicians must still use their best judgment regarding surgical timing and work to address modifiable risk factors to avoid complications. The unanswered question that remains is whether there is a skin perfusion or oxygenation issue at the root of these complications, which seems likely. Alternative approaches that can assess the wound more broadly and in real time, such as fluorescent probes, may be deserving of further investigation. Level II, diagnostic study.

Wearable Multimodal Vital Sign Monitoring Sensor With Fully Integrated Analog Front End

Cardiovascular disease (CVD) is a widespread disease and the leading cause of death worldwide. Home care is essential for patients with CVD, and it involves the daily monitoring of important CVD-related vital signs using methods including electrocardiography (ECG), heart rate monitoring, pulse oximetry (SpO2), and continuous blood pressure measurement. However, a wearable device that can monitor these parameters simultaneously remains unavailable; herein, we propose a lightweight, highly integrated sensor that can do so. In this sensor, an analog front end (AFE) integrated chip (IC) is implemented in the sensor to detect one-lead ECG and two-wavelength photoplethysmography (PPG) signals. The highly integrated IC minimizes both the size and power requirement of the sensor. Moreover, its comprehensive functions include adjustable gain, current compensation, lead off, and fast recovery—all of which are crucial for wearable applications in large populations. Accordingly, the sensor can apply the adaptive adjust method to automatically adjust the IC parameters to suit a range of applications and users. In addition, the heart rate is calculated from the R-R interval from the ECG signals, whereas the SpO2 is calibrated with a univariate quadratic equation with less than 1% mean error. Our sensor can also calculate the systolic blood pressure (SBP) and diastolic blood pressure (DBP) by using a support vector machine based calibration-less model with the features of infrared PPG and ECG signals. The model is trained on our pre-collected wearable dataset and has a mean error ± standard deviation of −2.10 ± 7.07 mmHg for SBP and 0.04 ± 7.34 mmHg for DBP in 16 volunteers. In conclusion, this paper reports on a multimodal, vital sign monitoring sensor—with small size, low power, and dynamic compatibility—suitable for patients with CVD under home care.

Detection of hypoxia by near-infrared spectroscopy and pulse oximetry: a comparative study.

.Significance: Pulse oximetry is widely used in clinical practice to monitor changes in arterial oxygen saturation (). However, decreases in can be delayed relative to the actual clinical event, and near-infrared spectroscopy (NIRS) may detect alterations in oxygenation earlier than pulse oximetry, as shown in previous cerebral oxygenation monitoring studies.Aim: We aim to compare the response of transcutaneous muscle NIRS measures of the tissue saturation index with pulse oximetry during hypoxia.Approach: Episodes of acute hypoxia were induced in nine anesthetized Yucatan miniature pigs. A standard pulse oximeter was attached to the ear of the animal, and a transcutaneous NIRS sensor was placed on the hind limb muscle. Hypoxia was induced by detaching the ventilator from the animal and reattaching it once the pulse oximeter reported 70% .Results: Twenty-four episodes of acute hypoxia were analyzed. Upon the start of hypoxia, the transcutaneous NIRS measures changed in , whereas the pulse oximetry measures changed in ().Conclusions: Transcutaneous muscle NIRS can detect the effects of hypoxia significantly sooner than pulse oximetry in the Yucatan miniature pig. A transcutaneous NIRS sensor may be used as an earlier detector of oxygen saturation changes in the clinical setting than the standard pulse oximeter.

Acute uveitic phase of Vogt-Koyanagi-Harada disease: optic nerve head swelling, ocular blood flow and retinal oxygen metabolism.

To investigate the association of optic nerve head (ONH) swelling in the acute uveitic phase of Vogt-Koyanagi-Harada (VKH) disease with blood flow velocity in the choroid and ONH and oxygen saturation and diameter of retinal vessels. In this prospective study, 25 patients (50 eyes) were studied. Thirteen patients (26 eyes) had ONH swelling and 12 patients (24 eyes) had no ONH swelling. Laser speckle flowgraphy (LSFG) and retinal oximetry measurements were performed at presentation. In the ONH, mean blur rate (MBR)-vessel, representing blood flow velocity in retinal vessels, was significantly lower in the eyes affected by ONH swelling, while choroidal MBR was not significantly different. Eyes with ONH swelling had a significantly lower oxygen saturation in retinal venules, a significantly higher arteriovenous oxygen saturation difference and a significantly smaller calibre of retinal arterioles compared with eyes without ONH swelling. There were significant positive correlations between the MBR-vessel of the ONH and venular oxygen saturation and calibre of retinal arterioles. In addition, MBR-vessel of the ONH had a significant negative correlation with arteriovenous oxygen saturation difference. The occurrence of ONH swelling in the acute uveitic phase of VKH disease is associated with lower retinal blood flow velocity and smaller calibre of retinal arterioles as well as lower oxygen saturation in retinal venules and higher arteriovenous difference in oxygen saturation.

0595 Inflammatory Plasma Biomarker Cluster Associations with Sleep in People with and without HIV

Abstract Introduction Sleep problems are commonly reported in people with HIV (PWH) and may be exacerbated by HIV-induced inflammation. We determined associations between systemic inflammation and objective/subjective sleep measures in PWH and demographically/lifestyle similar HIV-negative controls. Methods Objective sleep measures from 7-day actigraphy (e.g. mean/standard deviation (SD) of wake after sleep onset [WASO], sleep duration/efficiency), overnight oximetry (oxygen desaturation index [ODI]), and patient-reported measures (Insomnia Severity Index [ISI] and Patient-Reported Outcomes Measurement Information System [PROMIS] sleep questionnaires) were assessed in participants in the multicenter POPPY-Sleep Study in the UK and Ireland. Principal Component Analysis using 31 plasma inflammatory biomarkers followed by cluster analysis previously identified 3 distinct inflammatory clusters: 1 (low inflammation), 2 (immune activation) and 3 (systemic inflammation). Baseline characteristics and between-cluster differences in sleep outcomes were assessed using Kruskal-Wallis or logistic regression/Chi-squared tests. Results The 465 participants (74% PWH, median [interquartile range] age 54 [50-60] years) were mainly male (80%), men having sex with men (71%) and white (88%). Among PWH, most (98%) were on antiretroviral therapy, 92% had viral load ≤50 cps/mL and CD4 cell count was 610 [470-785] cells/mm3. Overall, 18% met ISI criteria for insomnia (ISI≥ 15), and other sleep measures suggested generally good sleep (e.g., ODI 3.1/hr [1.5-6.4]). Clusters 1 (n=209), 2 (n=47) and 3 (n=209) differed significantly for HIV status (73%, 60%, 78%, p=0.03); BMI (24.8, 25.9, 26.2 kg/m2, p=0.002); systolic blood pressure (126, 135, 126 mmHg, p=0.002); cardiovascular disease (39%, 28%, 53%, p=0.001) and arthritis (8%, 9%,16%, p=0.02) – all factors associated with sleep problems. There were no clinically relevant between-biomarker-cluster differences in the proportions with insomnia (17%, 18%, 20%) either before (p=0.76) or after (p=0.75) adjustment for potential confounders. Few associations were observed among other actigraphy, oximetry and PROMIS measures. Conclusion Despite observed differences in clinical factors associated with sleep problems, we found no consistent or strong associations between inflammatory biomarker clusters and a range of sleep outcomes. Although associations could exist with other sleep outcomes (e.g. sleep architecture) or biomarker types (e.g. cerebrospinal fluid) not assessed, our findings do not support a strong association between sleep and plasma inflammatory biomarkers in this population. Support (If Any) NIH R01HL131049

Success and time implications of SpO2 measurement through pulse oximetry among hospitalised children in rural Bangladesh: Variability by various device-, provider- and patient-related factors.

BackgroundHypoxaemia is one of the strongest predictors of mortality among children with pneumonia. It can be identified through pulse oximetry instantaneously, which is a non-invasive procedure but can be influenced by factors related to the specific measuring device, health provider and patient. Following WHO's global recommendation in 2014, Bangladesh decided to introduce pulse oximetry in paediatric outpatient services, ie, the Integrated Management of Childhood Illness (IMCI) services in 2019. A national committee updated the existing IMCI implementation package and decided to test it by assessing the pulse oximetry performance of different types of assessors in real-life inpatient settings.MethodsWe adopted an observational design and conducted a technology assessment among children admitted to a rural district hospital. Eleven nurses and seven paramedics received one-day training on pulse oximetry as assessors. Each assessor performed at least 30 pulse oximetry measurements on children with two types of handheld devices. The primary outcome of interest was obtaining a successful measurement of SpO2, defined as observing a stable (±1%) reading for at least 10 seconds. Performance time, ie, time taken to obtain a successful measurement of SpO2 was considered the secondary outcome of interest. In addition, we used Generalized Estimating Equation to assess the effect of different factors on the pulse oximetry performance.ResultsThe assessors obtained successful measurements of SpO2 in all attempts (n = 1478) except one. The median time taken was 30 (interquartile range (IQR) = 22-42) seconds, and within 60 seconds, 92% of attempts were successful. The odds of obtaining a successful measurement within 60 seconds were 7.3 (95% confidence interval (CI) = 3.7-14.2) times higher with a Masimo device than a Lifebox device. Similarly, assessors aged >25 years were 4.8 (95% CI = 1.2, 18.6) times more likely to obtain a successful measurement within 60 seconds. The odds of obtaining a successful measurement was 2.6 (95% CI = 1.6, 4.2) times higher among children aged 12-59 months compared to 2-11 months.ConclusionsOur study indicated that assessors could achieve the necessary skills to perform pulse oximetry successfully in real-life inpatient settings through a short training module, with some effect of device-, provider- and patient-related factors. The National IMCI Programme of Bangladesh can use these findings for finalising the national IMCI training modules and implementation package incorporating the recommendation of using pulse oximetry for childhood pneumonia assessment.

Evaluation of the robustness of cerebral oximetry to variations in skin pigmentation using a tissue-simulating phantom.

Clinical studies have demonstrated that epidermal pigmentation level can affect cerebral oximetry measurements. To evaluate the robustness of these devices, we have developed a phantom-based test method that includes an epidermis-simulating layer with several melanin concentrations and a 3D-printed cerebrovascular module. Measurements were performed with neonatal, pediatric and adult sensors from two commercial oximeters, where neonatal probes had shorter source-detector separation distances. Referenced blood oxygenation levels ranged from 30 to 90%. Cerebral oximeter outputs exhibited a consistent decrease in saturation level with simulated melanin content; this effect was greatest at low saturation levels, producing a change of up to 15%. Dependence on pigmentation was strongest in a neonatal sensor, possibly due to its high reflectivity. Overall, our findings indicate that a modular channel-array phantom approach can provide a practical tool for assessing the impact of skin pigmentation on cerebral oximeter performance and that modifications to algorithms and/or instrumentation may be needed to mitigate pigmentation bias.

Home monitoring of lung function, symptoms and quality of life after admission with COVID-19 infection: The HOMECOMIN' study.

Background and objectiveTo develop targeted and efficient follow‐up programmes for patients hospitalized with coronavirus disease 2019 (COVID‐19), structured and detailed insights in recovery trajectory are required. We aimed to gain detailed insights in long‐term recovery after COVID‐19 infection, using an online home monitoring programme including home spirometry. Moreover, we evaluated patient experiences with the home monitoring programme.MethodsIn this prospective multicentre study, we included adults hospitalized due to COVID‐19 with radiological abnormalities. For 6 months after discharge, patients collected weekly home spirometry and pulse oximetry measurements, and reported visual analogue scales on cough, dyspnoea and fatigue. Patients completed the fatigue assessment scale (FAS), global rating of change (GRC), EuroQol‐5D‐5L (EQ‐5D‐5L) and online tool for the assessment of burden of COVID‐19 (ABCoV tool). Mixed models were used to analyse the results.ResultsA total of 133 patients were included in this study (70.1% male, mean age 60 years [SD 10.54]). Patients had a mean baseline forced vital capacity of 3.25 L (95% CI: 2.99–3.44 L), which increased linearly in 6 months with 19.1% (Δ0.62 L, p < 0.005). Patients reported substantial fatigue with no improvement over time. Nevertheless, health status improved significantly. After 6 months, patients scored their general well‐being almost similar as before COVID‐19. Overall, patients considered home spirometry useful and not burdensome.ConclusionSix months after hospital admission for COVID‐19, patients' lung function and quality of life were still improving, although fatigue persisted. Home monitoring enables detailed follow‐up for patients with COVID‐19 at low burden for patients and for the healthcare system.

Changes in ocular blood flow and retinal oxygen metabolism during immunosuppressive therapy for initial-onset acute uveitis associated with Vogt-Koyanagi-Harada disease.

Purpose The aim of this study was to investigate the correlations between visual acuity, blood flow velocity in the choroid and optic nerve head (ONH) and oxygen saturation and calibre of retinal vessels during immunosuppressive therapy in patients with initial-onset acute uveitis associated with Vogt–Koyanagi–Harada (VKH) disease. Methods In this prospective study, 20 patients were studied. Laser speckle flowgraphy (LSFG) and retinal oximetry measurements were performed at baseline and at 4, 8 and 12 weeks after treatment. Results After immunosuppressive therapy, best-corrected visual acuity (BCVA) improved significantly at each post-treatment time-point compared with baseline value. Mean blur rate (MBR), representing blood flow velocity, in the choroid and ONH (overall and vessel areas) significantly increased. On the contrary, oxygen saturation of retinal arterioles and venules and calibre of retinal venules significantly decreased. There were significant negative correlations between ONH MBR vessel and arteriovenous oxygen saturation difference at baseline and at 4 weeks after treatment and between MBR tissue of the ONH and arteriovenous oxygen saturation difference at week 12 after treatment. Conclusions Immunosuppressive therapy in patients with initial-onset acute uveitis associated with VKH disease is associated with improved blood flow velocity in choroid and ONH and normalization of retinal oxygen metabolism and calibre of retinal venules. These correspond with improved visual acuity. These findings help explain the pathophysiology of VKH disease and its treatment and may provide biomarkers for choroiditis activity and response to treatment.