Oximetry Readings Research Articles

Counterpoint: The value of including patients in prerounding.

Counterpoint: The value of including patients in prerounding.

Factors associated with prolonged postoperative length of hospital stay after laparoscopic colorectal cancer resection: a secondary analysis of a randomized controlled trial

BackgroundThe postoperative length of hospital stay (PLOS) is an important indicator of surgical quality. We identified perioperative factors that affect prolonged PLOS (PPLOS) after laparoscopic colorectal cancer resection, which is the preferred surgical approach for colorectal cancer, the third most common cancer.MethodsThis study was a secondary analysis of a randomized trial (clinicaltrials.gov ID: NCT03160144) that included 280 patients who underwent laparoscopic colorectal cancer resection. The primary outcome was a PPLOS, defined as a PLOS that was longer than the median PLOS. Baseline, anesthetic, surgical, and postoperative management factors were included in the univariate and multivariate analyses to identify factors influencing PPLOS.ResultsThe median PLOS was 10 days, and 117 patients had a PPLOS. We identified six influencing factors for PPLOS: preoperative pulse oxygen saturation < 96% (odds ratio [OR], 3.09 [95% confidence interval (CI) 1.38–6.92]; P = 0.006), distant tumor metastasis (OR, 0.34 [95% CI 0.13–0.91]; P = 0.031), the Miles procedure or left hemicolectomy (OR, 4.51 [95% CI 1.67–12.18]; P = 0.003), perioperative surgical events (OR, 2.44 [95% CI 1.25–4.76]; P = 0.009), postoperative albumin infusion (OR, 2.19 [95% CI 1.14–4.19]; P = 0.018), and postoperative early ambulation (OR, 0.35 [95% CI 0.18–0.68]; P = 0.002). Further stratified analysis showed that postoperative albumin infusion might be a risk factor for PPLOS, even in patients with a preoperative albumin level < 40 g/L (OR, 2.29 [95% CI 0.98–5.34]; P = 0.056) or duration of surgery ≥ 3 h (OR, 2.52 [95% CI 1.08–5.87]; P = 0.032).ConclusionsA low preoperative pulse oximetry reading, complex surgical procedures, perioperative surgical events, and postoperative albumin infusion may be risk factors for PPLOS after laparoscopic colorectal cancer resection, whereas distant tumor metastasis and postoperative early ambulation might be protective factors. The association between postoperative albumin infusion, a modifiable factor, and PLOS or clinical outcomes warrants further investigation.

Reference values for babies' pulse oximetry recordings, highlighting the impact of cesarean sections and COVID-19 pandemic

Background: With a focus on the consequences of caesarean delivery as a result of mother stress and the first wave of the COVID-19 epidemic as a source of maternal stress, the study sought to identify reference values for pulse oximetry recordings among both healthy full-term neonates and preterm and unhealthy neonates.Methods: A comparative study of 170 neonates admitted to the Fayoum university NICU after being born in the department of obstetrics and gynaecology. Collected pulse oximetry readings at predetermined intervals was done. Patients were classified into group I (before 1st wave of COVID-19 pandemic) and group II (during 1st wave of COVID-19 pandemic).Results: The 5th and 95th percentiles of SpO2 after 1 minute after birth were (65% to 90%), with a mean of 77%, according to the study of 146 full-term healthy newborns. SpO2 readings were (89% to 97.1%) with a mean of 92% after 5 minutes, and finally (90% to 98%) with a mean of 93% after 10 minutes. Statistically significant lower means of SpO2 were found during 1st wave of COVID-19 pandemic after 10 minutes of delivery, and for Apgar score after 1 and 5 minutes of delivery. There was a negative impact of cesarean section delivery on gestational age.Conclusions: This research reveals that after 10 minutes of delivery, a Spo2 recorded range of 90 to 98 for full-term healthy neonates and a mean of 86% for preterm and ill neonates may be appropriate. The first wave of the COVID-19 pandemic had a deleterious impact on neonates' SpO2 recordings and Apgar scores, according to the study. There was a gestational age effect associated with caesarean delivery.

Differential pulse oximetry readings between ethnic groups and delayed transfer to intensive care units.

Pulse oximeters are widely used to monitor blood oxygen saturations, although concerns exist that they are less accurate in individuals with pigmented skin. This study aimed to determine if patients with pigmented skin were more severely unwell at the period of transfer to intensive care units (ICUs) than individuals with White skin. Using data from a large teaching hospital, measures of clinical severity at the time of transfer of patients with COVID-19 infection to ICUs were assessed, and how this varied by ethnic group. Data were available on 748 adults. Median pulse oximetry demonstrated similar oxygen saturations at the time of transfer to ICUs (Kruskal-Wallis test, P = 0.51), although median oxygen saturation measurements from arterial blood gases at this time demonstrated lower oxygen saturations in patients classified as Indian/Pakistani ethnicity (91.6%) and Black/Mixed ethnicity (93.0%), compared to those classified as a White ethnicity (94.4%, Kruskal-Wallis test, P = 0.005). There were significant differences in mean respiratory rates in these patients (P < 0.0001), ranging from 26 breaths/min in individuals with White ethnicity to 30 breaths/min for those classified as Indian/Pakistani ethnicity and 31 for those who were classified as Black/Mixed ethnicity. These data are consistent with the hypothesis that differential measurement error for pulse oximeter readings negatively impact on the escalation of clinical care in individuals from other than White ethnic groups. This has implications for healthcare in Africa and South-East Asia and may contribute to differences in health outcomes across ethnic groups globally.

Interpretation of Oxygen Saturation in Congenital Heart Disease: Fact and Fallacy.

Oxygen saturation is the percentage of hemoglobin that is saturated with oxygen, converting it to oxyhemoglobin. Oxygen saturation is a critical part of the physical examination of children with congenital heart disease (CHD). The expected oxygen saturation of a patient with CHD depends on their anatomical lesion, their previous surgeries, and any additional pulmonary or systemic pathology that may derange their saturation. Oxygen saturation can be noninvasively measured using pulse oximetry. Pulse oximetry is based on the differential absorption of infrared and red light by oxyhemoglobin and deoxyhemoglobin, with the former absorbing more infrared than the latter. Pulse oximetry readings may be inaccurate in settings of low cardiac output, peripheral vasoconstriction, arrhythmia, hypothermia, and venous pulsations. The use of pulse oximetry in the care of a child with CHD begins with the newborn critical CHD screen. A failed screen indicates a need for further investigation, such as repeated pulse oximetry or echocardiography. The oxyhemoglobin dissociation curve may be used to estimate the partial pressure of oxygen in the blood at various oxygen saturations. It is also a marker of the affinity of hemoglobin for oxygen, with a right-shifted curve indicating a higher oxygen tension needed to saturate hemoglobin. This is a helpful adaptation of the body to situations of stress such as fever, acidosis, and hypercapnia. An understanding of these concepts is paramount for providers caring for patients with known or potential CHD in any setting to appropriately interpret and respond to abnormal saturations for each child.

Racial bias and reproducibility in pulse oximetry among medical and surgical inpatients in general care in the Veterans Health Administration 2013-19: multicenter, retrospective cohort study

ObjectivesTo evaluate measurement discrepancies by race between pulse oximetry and arterial oxygen saturation (as measured in arterial blood gas) among inpatients not in intensive care.DesignMulticenter, retrospective cohort study using electronic...

Impact of ethnicity on the accuracy of measurements of oxygen saturations: A retrospective observational cohort study

SummaryBackgroundPulse oximeters are routinely used in community and hospital settings worldwide as a rapid, non-invasive, and readily available bedside tool to approximate blood oxygenation. Potential racial biases in peripheral oxygen saturation (SpO2) measurements may influence the accuracy of pulse oximetry readings and impact clinical decision making. We aimed to assess whether the accuracy of oxygen saturation measured by SpO2, relative to arterial blood gas (SaO2), varies by ethnicity.MethodsIn this large retrospective observational cohort study covering four NHS Hospitals serving a large urban population in Birmingham, United Kingdom, consecutive pairs of SpO2 and SaO2 measurements taken on the same patient within an interval of less than 20 min were identified from electronic patient records. Where multiple pairs of measurements were recorded in a spell, only the first was included in the analysis. The differences between SpO2 and SaO2 measurements were compared across groups of self-identified ethnicity. These differences were subsequently adjusted for age, sex, bilirubin, systolic blood pressure, carboxyhaemaglobin saturations and the time interval between SpO2 and SaO2 measurements.FindingsPaired O2 saturation measurements from 16,818 inpatient spells between 1st January 2017 and 18th February 2021 were analysed. The cohort self-identified as being of White (81.2%), Asian (11.7%), Black (4.0%), or Other (3.2%) ethnicities. Across the cohort, SpO2 was statistically significantly higher than SaO2 (p < 0.0001), with medians of 98% (interquartile range [IQR]: 95–100%) vs. 97% (IQR: 96–99%), and a median difference of 0.5% points (pps; 95% confidence interval [CI]: 0.5–0.6). However, the size of this difference varied considerably with the magnitude of SaO2, with SpO2 overestimating by a median by 3.8pp (IQR: 0.4, 8.8) for SaO2 values <90% but underestimating by a median of 0.4pp (IQR: -2.0, 1.4) for an SaO2 of 95%. The differences between SpO2 and SaO2 were also found to vary by ethnicity, with this difference being 0.8pp (95% CI: 0.6–1.0, p < 0.0001) greater in those of Black vs. White ethnicity. These differences resulted in 8.7% vs. 6.1% of Black vs. White patients who were classified as normoxic on SpO2 actually being hypoxic on the gold standard SaO2 (odds ratio: 1.47, 95% CI: 1.09–1.98, p = 0.012).InterpretationPulse oximetry may overestimate O2 saturation, and this is possibly more pronounced in patients of Black ethnicity. Prospective studies are urgently warranted to assess the impact of ethnicity on the accuracy of pulse oximetry, to ensure care is optimised for all.FundingPIONEER, the Health Data Research UK (HDR-UK) Health Data Research Hub in acute care.

Perioperative Tissue Oximetry-driven Fluid Resuscitation Improves Flap Perfusion in Autologous Free Tissue Breast Reconstruction.

Introduction:The use of tissue oximetry for monitoring following free tissue transfer has become a common practice to facilitate early detection of poor flap perfusion. We hypothesized that T stat readings may guide fluid administration in the postoperative period and improve perfusion in patients undergoing autologous breast reconstruction.Methods:Patients undergoing free flap breast reconstruction from 2015 to 2018 were reviewed. Mean percutaneous oximetry readings of the first four postoperative days were recorded. The mean change at 24 hours from the original reading was calculated (∆TO). The study population was divided in two groups based on whether administration of intravenous fluids (IVFs) was increased/maintained (group 1) or decreased (group 2) after postoperative day 1.Results:A total of 120 patients were identified. The mean age was 53, and mean BMI was 33. Overall, patients for whom fluid administration was decreased experienced an increase in their tissue perfusion, while patient who received a bolus or maintained the same rate of IVF experienced a decrease. Patients who had a negative ∆TO experienced a statistically significant difference between groups 1 and 2 at 24 and 72 hours (–4 versus +3 and –11 versus +13, respectively). For patients with a positive ∆TO, although decreasing fluids resulted in higher readings, it did not reach statistical significance at 24 or 72 hours (0 versus +2 and +4 versus +6, respectively).Conclusions:In patients undergoing free tissue breast reconstruction, tissue oximetry readings may be used as a novel guide for postoperative fluid management.

Invasive And Non-invasive Assessment Of Arterial Blood Oxygen Saturation In Patients With Continuous Flow LVADs: Is There A Correlation?

<h3>Background</h3> Patients with continuous flow left ventricular assist devices (CF-LVAD) typically have a narrow pulse pressure. This may pose a challenge for transcutaneous automated pulse oximeter devices to accurately measure arterial blood saturation. This study aimed to assess their accuracy in a CF-LVAD population by comparing pulse oximetry readings to invasive arterial blood gas (ABG) measurements. <h3>Methods</h3> A total of eighteen patients with a CF-LVAD were identified using chart review at the University of Minnesota and Minneapolis Heart Institute. All, except one patient were implanted with a HeartMate III device (Abbott Laboratories, Minneapolis, MN). Non-invasively assessed oxygen saturation was compared to simultaneously obtained arterial blood oxygen saturation. Two patients were receiving mechanical ventilation, one received BiPAP support, and 15 patients were either breathing room air or receiving supplemental oxygen by nasal cannula. <h3>Results</h3> A non-invasive pulse oximeter read was obtained on every patient. There was a moderate correlation between the invasively and non-invasively obtained oxygen saturation values as shown in Figure 1 (R²=0.624). Waveform quality, as assessed by the treating physician, qualified as good or acceptable in 16 cases and as poor for 2 patients. Data points for these 2 patients are marked in red in Figure 1. <h3>Conclusion</h3> Despite a narrow pulse pressure in patients with CF-LVAD, non-invasive pulse oximetry provided a reliable assessment of arterial blood saturation when compared to the gold standard ABG measurement. This finding presents an opportunity to conduct future studies in this patient population in which continuous monitoring of oxygen saturation may be necessary, such as evaluation for obstructive sleep apnea.

Efficacious Continuous Monitoring of Infants Using Wireless Remote Monitoring Technology.

ObjectiveTo compare postductal heart rate and saturation (SpO2) measurements from the wireless PO device obtained by iVital+ against measurements by the standard Masimo (SET technology) monitor in the monitoring of neonates.MethodsPulse oximetry reading of newborns were assessed in terms of heart rate and saturations with two PO simultaneously attached to postductal site and data comparison was done.ResultsOut of the 1000 cumulative recordings, the mean difference between HR obtained from both PO was 0.415 and level of agreement was 2.3 beats per minute. For SpO2 mean difference between devices was 1.21 and level of agreement was 1.5%. There was very little difference between SpO2 measurements when the Masimo SpO2 was ≥ 70%.ConclusionAs this pulse oximeter is small, portable and accuracy is as comparable to Masimo, this provides a good solution for efficaciously monitoring neonates. It can also be used in the monitoring of children with suspected or affected with COVID-19 in hospital and ICU settings as also in the quarantine facilities. This reduces the need for constant presence of medical and nursing personnel.

An observational study of simultaneous pulse oximetry and arterial oxygen saturation readings in intensive care unit/high dependency unit in COVID-19 patients

Background: The coronavirus-2019 (COVID-19) pandemic has increased the use of pulse oximeters worldwide. It has become an inevitable tool in the monitoring of the disease. However, the accuracy of pulse oximeters in COVID-19 has not been established. Aims and Objectives: The aims of the study were to examine the relationship between oxygen saturation as measured by pulse oximeter (SpO2) and oxygen saturation measured by arterial blood gas analysis (SaO2) measurements in COVID-19 patients admitted to the intensive care unit (ICU)/high dependency unit (HDU) and to assess the ability of SpO2 readings to detect low SaO2 and low oxygen tension in COVID-19 patients. Materials and Methods: This prospective observational study was conducted in the COVID-19 ICU and high dependency unit of a tertiary care hospital in Bengaluru, India. All patients admitted with confirmed COVID-19, meeting the eligibility criteria, were included in the study. We assessed bias and limits of agreement between paired samples of oxygen saturation from pulse oximetry (SpO2) and arterial oxygen saturation from blood gas analysis (SaO2). Results: The sample mean difference SpO2-SaO2 is −0.86% (bias) and the 95% confidence interval for the mean difference was −1.67 and −0.04. The lower limit of agreement was −7.32 with a 95% confidence interval (−8.74, −5.91). The upper limit of agreement was 5.61 with a 95% confidence interval of 4.19 and 7.02. Conclusion: SpO2 values are not completely dependable in estimating SaO2 in COVID-19 patients in ICU/HDU; therefore, arterial blood gas analysis measurement of oxygen saturation has to be done depending on the clinical scenario CTRI (CTRI/2020/11/029035).

Rapid Patient-Side Evaluation of Endothelial Glycocalyx Thickness in Healthy Sedated Cats Using GlycoCheck® Software.

The endothelial glycocalyx (EG) determines transvascular fluid fluxes, and influences inflammation, coagulation, and capillary blood flow. The GlycoCheck® software calculates EG thickness using sidestream dark field videomicroscopy recordings. This method has not been evaluated for use in cats. The aim of the present study was to evaluate the use of GlycoCheck® for estimating EG thickness in healthy cats, and to investigate the variability of EG thickness in this population. One hundred and one healthy research-purposed cats were included in the study. The cats were sedated, and a handheld videomicroscope, connected to GlycoCheck® software, was used to evaluate the sublingual microvasculature. The parameters measured included perfused boundary region (PBR, an indirect measurement of EG thickness) in vessels between 5 and 25 μm in diameter, valid vessel density, percentage red blood cell filling, and median red blood cell column width. Heart rate, respiratory rate, pulse oximetry and oscillometric blood pressure readings were also recorded. There were 35 neutered male cats, 11 intact males, 38 neutered females, and 17 intact females. The average age was 63 months (range, 11–160 months). Tolerance intervals for PBR (vessel diameter 5–25 μm) were 1.89–3.00 μm (95% CI, lower limit 1.76–2.04, upper limit 2.83–3.13 μm); for valid vessel density were 73.33–333.33 μm/mm2 (95% CI, lower limit 77.00–99.33, upper limit 312.67–350.33 μm/mm2); for percentage red blood cell filling were 59.85–85.07% (95% CI, lower limit 58.97–63.33, upper limit 83.07–88.20 %); and for median red blood cell column width were 5.63–8.59 μm (95% CI, lower limit 5.28–6.07, upper limit 8.14–9.51 μm). There was a negative association between median red blood cell column width and body weight (p = 0.007). The median red blood cell column was significantly wider in intact females when compared to spayed females (p = 0.033). The GlycoCheck® analysis was easily performed in healthy sedated cats. Clinical variables did not have an effect on the EG thickness. These results suggest that this technique could be valuable for evaluation of the EG and microvascular parameters in cats.

Comparison of forehead and finger oximetry sensors during the six minute walk test.

BackgroundMeasurement of oxygen saturation (SpO2) during the 6 minute walk test (6MWT) could be impacted by the measurement site.AimsTo compare SpO2 and heart rate (HR) between forehead and finger sensors during the 6MWT. Sensor readings were also to be compared for signal quality and with capillary blood gas (CBG) pre and post 6MWT.Method80 subjects with pulmonary vascular disease (PVD) and/or interstitial lung disease (ILD) performed the 6MWT. Pulse oximetry was recorded at 30 s intervals. CBG was taken pre and post 6MWT to determine capillary oxygen saturation (SCO2).ResultsThe forehead sensor recorded higher values for SpO2 (p < 0.001) and HR (p < 0.01) compared with the finger sensor during the 6MWT. For both sensors, the demonstrated bias compared to CBG post 6MWT was higher and more variable in subjects who desaturated. During the 6MWT there was a higher occurrence (p < 0.001) of poor signal quality in the finger sensor compared with the forehead sensor.ConclusionThis study suggests that the sensor site can impact pulse oximetry readings. The variance in bias suggests pulse oximetry may not accurately reflect SCO2 measurements particularly in subjects who desaturate during 6MWT.

DIFFUSE LARGE B-CELL LYMPHOMA PRESENTING AS DIFFUSE BILATERAL INNUMERABLE PULMONARY NODULES

TOPIC: Lung Cancer TYPE: Medical Student/Resident Case Reports INTRODUCTION: Diffuse large B-cell lymphoma (DLBCL) may rarely manifest as a primary pulmonary lymphoma or with secondary lung involvement. Typical radiologic presentations include chronic, indolent airspace consolidations, focal lung masses or perilymphatic lung nodules.(1) The objective of this report is to present rare secondary pulmonary involvement of DLBCL presenting as bilateral diffuse innumerable pulmonary nodules on chest computed tomographic (CT) imaging. This radiologic presentation has only previously been seen in the setting of acquired immunodeficiency syndrome (AIDS).(2) CASE PRESENTATION: A 67-year-old Caucasian woman with a history of stage IV DLBCL associated with a chest wall mass presented to the emergency department with chest pain and progressively worsening shortness of breath. Increasing oxygen requirements from baseline of 2L to 4L via nasal cannula, to maintain a pulse oximetry reading of 95% was noted. Physical examination was unremarkable with clear lung fields.Serology revealed bi-cytopenia, hemoglobin 11.0g/dL (normal 11.5-15.5g/dL) and platelets 81 k/uL (normal 150-400k/uL). LDH and CRP were elevated at 527U/L (normal 135-214U/L) and 6.4mg/dL (normal <0.9mg/dL) respectively. CT-chest with contrast showed no evidence of pulmonary embolism. However, innumerable bilateral diffuse lung nodules were noted (Figure 1). The left lower chest wall mass had increased in size. Broncho-alveolar lavage was negative for viral, bacterial and fungal etiologies. HIV serology, acid fast bacillus culture and stain were also negative. Transbronchial needle aspirate of enlarged lymph nodes was positive for lymphoma. Left lower lobe trans-bronchial biopsy revealed mild non-specific interstitial fibrosis but no granulomatous inflammation, neoplasm, or evidence of acute infection. Due to high suspicion of progression of her DLBCL as the underlying cause of her lung nodules, CT-guided biopsy of the lung nodules in the left lower lobe was performed. Diffuse sheets of large, CD5, 10 and 20 positive transformed lymphocytes were seen. Her diffuse bilateral innumerable pulmonary nodules were proven to be due to progression of her DLBCL disease. She received chemotherapy with bendamustine and rituximab. Her chest pain and oxygen requirements returned to her baseline, and she was discharged home one week later. DISCUSSION: This was a case of a 67-year-old Caucasian woman with stage IV DLBCL and secondary pulmonary involvement. Typical radiologic presentation of DLBCL with secondary pulmonary involvement is with a focal lung mass or perilymphatic lung nodules.(2) However, this patient presented with extensive bilateral diffuse innumerable pulmonary nodules unlike previous radiologic presentations of DLBCL described in immunocompetent patients. CONCLUSIONS: We suspect her pulmonary involvement was due to lymphatic spread of her DLBCL which may rarely occur in the setting of generalized disease.(3) REFERENCE #1: Lewis E, Caskey C, Fishman E. Lymphoma of the lung: CT Findings in 31 patients. AJR Am J Roentgenol. 1991 Apr;156(4):711-4. REFERENCE #2: Harbor N. Rapidly progressive diffuse large B-cell lymphoma presenting as innumerable pulmonary nodules in an Aids patient: A fatal case report. Journal of Hospital Medicine. 2015 March;abstract 604(10)supply 2. REFERENCE #3: Cheng C, Su Y, Chao T et al. Intralymphatic spread is a rare finding associated with poor prognosis in diffuse large B-cell lymphoma with extranodal involvements. Am J Surg Pathol. 2018 May;42(5):616-624. DISCLOSURES: No relevant relationships by Tanya Marshall, source=Web Response No relevant relationships by Atul Mehta, source=Web Response No relevant relationships by Prince Ntiamoah, source=Web Response No relevant relationships by Joseph Parambil, source=Web Response

Pulse oximetry and supplemental oxygen use in nationwide Veterans Health Administration hospitals, 2013–2017: a Veterans Affairs Patient Database validation study

ObjectiveExtraction and standardisation of pulse oximetry and supplemental oxygen data from electronic health records has the potential to improve risk-adjustment, quality assessment and prognostication. We develop an approach to standardisation...

Racial Bias in Pulse Oximetry Measurement Among Patients About to Undergo Extracorporeal Membrane Oxygenation in 2019-2020: A Retrospective Cohort Study

Pulse oximeters may produce less accurate results in non-White patients. Do pulse oximeters detect arterial hypoxemia less effectively in Black, Hispanic, and/or Asian patients than in White patients in respiratory failure and about to undergo extracorporeal membrane oxygenation (ECMO)? Data on adult patients with respiratory failure readings 6h before ECMO were provided by the Extracorporeal Life Support Organization registry. Data was collected from 324 centers between January 2019 and July 2020. Our primary analysis was of rates of occult hypoxemia-low arterial oxygen saturation (Sao2≤ 88%) on arterial blood gas measurement despite a pulse oximetry reading in the range of 92%to 96%. The rate of pre-ECMO occult hypoxemia, that is, arterial oxygen saturation (Sao2)≤ 88%, was 10.2%(95%CI, 6.2%-15.3%) for 186 White patients with peripheral oxygen saturation (Spo2) of 92%to 96%; 21.5%(95%CI, 11.3%-35.3%) for 51 Black patients (P= .031 vsWhite); 8.6%(95%CI, 3.2%-17.7%) for 70 Hispanic patients (P= .693 vsWhite); and 9.2%(95%CI, 3.5%-19.0%) for 65 Asian patients (P= .820 vsWhite). Black patients with respiratory failure had a statistically significantly higher risk of occult hypoxemia with an OR of 2.57 (95%CI, 1.12-5.92) compared with White patients (P= .026). The risk of occult hypoxemia for Hispanic and Asian patients was equivalent to that of White patients. In a secondary analysis of patients with Sao2≤ 88%despite Spo2 > 96%, Black patients had more than three times the risk compared with White patients (OR, 3.52; 95%CI, 1.12-11.10; P= .032). Compared with White patients, the prevalence of occult hypoxemia was higher in Black patients than in White patients about to undergo ECMO for respiratory failure, but it was comparable in Hispanic and Asian patients compared with White patients.

Multilayer perceptron neural network model development for mechanical ventilator parameters prediction by real time system learning

Background and objectiveIn pandemic situations like COVID 19, real time monitoring of patient condition and continuous delivery of inspired oxygen can be made possible only through artificial intelligence-based system modeling. Even now manual control of mechanical ventilator parameters is continuing despite the ever-increasing number of patients in critical epidemic conditions. Here a suggestive multi-layer perceptron neural network model is developed to predict the level of inspired oxygen delivered by the mechanical ventilator along with mode and positive end expiratory pressure (PEEP) changes for reducing the effort of health care professionals. MethodsThe artificial neural network model is developed by Python programming using real time data. Parameter identification for model inputs and outputs is done by in corporating consistent real time patient data including periodical arterial blood gas analysis, continuous pulse oximetry readings and mechanical ventilator settings using statistical pairwise analysis using R programming. ResultsMean square error values and R values of the model are calculated and found to be an average of 0.093 and 0.81 respectively for various data sets. Accuracy loss will be in good fit with validation loss for a comparable number of epochs. ConclusionsComparison of the model output is undertaken with physician’s prediction using statistical analysis and shows an accuracy error of 4.11 percentages which is permissible for a good predictive system.

Silent hypoxaemia in COVID-19: Journey through ICU

Silent hypoxia is a well-known entity associated with SARSCoV-2 [1,2]. It is a condition where despite the patient being hypoxic, they do not show any signs and symptoms of respiratory distress [2]. Hypoxia can only be detected either by pulse oximetry reading or through blood gas analysis. These patients may have variable radiological appearances on presentation. Many studies have shown silent hypoxia has a high incidence of 20-40% with patients with SARS-CoV-2 pneumonia [2,3]. Some patients need intensive care support and some recover without any supports. Here we present a series of chest radiographs of a patient presented with silent hypoxia. A previously well 53 year old male presented to a COVID-19 treatment facility with a positive antigen testing. At the time of admission, the patient was well with a respiratory rate of 16/min and stable haemodynamics. There were no other signs and symptoms of respiratory distress. His routine pulse oximetry reading was 66% with an arterial oxygen partial pressure of 56 mmHg. The first chest radiograph showed an extensive air space opacification (Figure 1). The appearance was so severe and did not match with his clinical picture. An entity of silent hypoxia was diagnosed, and he was admitted to the Intensive care unit and started on face mask oxygen through 60% venturi.

Decreased Pulse Oximetry Readings in Asymptomatic Patient with Hemoglobin Grifton

Hemoglobin Grifton presents as a decreased oxygen saturation as measured by pulse oximetry (SpO2) reading despite a normal arterial oxygen saturation (SaO2) in an asymptomatic patient. Hemoglobin Grifton is caused by a mutation on an alpha chain of hemoglobin at codon 87, which affects the absorption wavelength of its oxyhemoglobin. A standard pulse oximeter is designed to measure the absorption of light at specific wavelengths and perceives the hemoglobin Grifton oxyhemoglobin as a deoxyhemoglobin. In a patient with a known variant hemoglobin, ordering additional diagnostic or therapeutic testing can increase stress for a patient requiring routine medical interventions or emergencies. Careful evaluation of each individual case is warranted prior to proceeding with an anesthetic.

Incidence of hyperoxia in trauma patients receiving pre-hospital emergency anaesthesia: results of a 5-year retrospective analysis

BackgroundPrevious studies have demonstrated an association between hyperoxia and increased mortality in various patient groups. Critically unwell and injured patients are routinely given high concentration oxygen in the pre-hospital phase of care. We aim to investigate the incidence of hyperoxia in major trauma patients receiving pre-hospital emergency anesthesia (PHEA) in the pre-hospital setting and determine factors that may help guide clinicians with pre-hospital oxygen administration in these patients.MethodsA retrospective cohort study was performed of all patients who received PHEA by a single helicopter emergency medical service (HEMS) between 1 October 2014 and 1 May 2019 and who were subsequently transferred to one major trauma centre (MTC). Patient and treatment factors were collected from the electronic patient records of the HEMS service and the MTC. Hyperoxia was defined as a PaO2 > 16 kPA on the first arterial blood gas analysis upon arrival in the MTC.ResultsOn arrival in the MTC, the majority of the patients (90/147, 61.2%) had severe hyperoxia, whereas 30 patients (20.4%) had mild hyperoxia and 26 patients (19.7%) had normoxia. Only 1 patient (0.7%) had hypoxia. The median PaO2 on the first arterial blood gas analysis (ABGA) after HEMS handover was 36.7 [IQR 18.5–52.2] kPa, with a range of 7.0–86.0 kPa. SpO2 pulse oximetry readings before handover were independently associated with the presence of hyperoxia. An SpO2 ≥ 97% was associated with a significantly increased odds of hyperoxia (OR 3.99 [1.58–10.08]), and had a sensitivity of 86.7% [79.1–92.4], a specificity of 37.9% [20.7–57.8], a positive predictive value of 84.5% [70.2–87.9] and a negative predictive value of 42.3% [27.4–58.7] for the presence of hyperoxemia.ConclusionTrauma patients who have undergone PHEA often have profound hyperoxemia upon arrival at hospital. In the pre-hospital setting, where arterial blood gas analysis is not readily available a titrated approach to oxygen therapy should be considered to reduce the incidence of potentially harmful tissue hyperoxia.