Pulse oximetry for the diagnosis and management of acute respiratory distress syndrome

Unraveling relevant cross-waves pattern drifts in patient-hospital risk factors among hospitalized COVID-19 patients using explainable machine learning methods

BACKGROUND

Several studies explored factors related to adverse clinical outcomes among COVID-19 patients but lacked analysis of the impact of the temporal data shifts on the strength of association between different predictors and adverse outcomes. This study aims to evaluate factors related to patients and hospitals in the prediction of in-hospital mortality, need for invasive mechanical ventilation (IMV), and intensive care unit (ICU) transfer throughout the pandemic waves.

METHODS

This multicenter retrospective cohort included COVID-19 patients from 39 hospitals, from March/2020 to August/2022. The pandemic was divided into waves: 10/03/2020-14/11/2020 (first), 15/11/2020-25/12/2021 (second), 26/12/2021-03/08/2022 (third). Patient-related factors included clinical, demographic, and laboratory data, while hospital-related factors covered funding sources, accreditation, academic status, and socioeconomic characteristics. Shapley additive explanation (SHAP) values derived from the predictions of a light gradient-boosting machine (LightGBM) model were used to assess potential risk factors for death, IMV and ICU.

RESULTS

Overall, 16,958 adult patients were included (median age 59 years, 54.7% men). LightGBM achieved competitive effectiveness metrics across all periods. Temporal drifts were observed due to a decrease in various metrics, such as the recall for the positive class [ICU: 0.4211 (wave 1) to 0.1951 (wave 3); IMV: 0.2089 (wave 1) to 0.0438 (wave 3); death: 0.2711 (wave 1) to 0.1175 (wave 3)]. Peripheral arterial oxygen saturation to the fraction of inspired oxygen ratio (SatO2/FiO2) at admission had great predictive capacity for all outcomes, with an optimal cut-off value for death prediction of 227.78. Lymphopenia had its association strength increased over time for all outcomes, optimal threshold for death prediction of 643 × 109/L. Thrombocytopenia was the most important feature in wave 2 (ICU); overall, values below 143,000 × 109/L were more related to death.

CONCLUSION

Data drifts were observed in all scenarios, affecting potential predictive capabilities of explainable machine learning methods. Upon admission, SatO2/FiO2 values, platelet and lymphocyte count were significant predictors of adverse outcomes in COVID-19 patients. Overall, inflammatory response markers were more important than clinical characteristics. Limitations included sample representativeness and confounding factors. Integrating the drift's knowledge into models to improve effectiveness is a challenge, requiring continuous updates and monitoring of performance in real-world applications.

CLINICAL TRIAL NUMBER

Not applicable.

A Sensor-Based Classification for Neuromotor Robot-Assisted Rehabilitation

Neurological diseases leading to motor deficits constitute significant challenges to healthcare systems. Despite technological advancements in data acquisition, sensor development, data processing, and virtual reality (VR), a suitable framework for patient-centered neuromotor robot-assisted rehabilitation using collective sensor information does not exist. An extensive literature review was achieved based on 124 scientific publications regarding different types of sensors and the usage of the bio-signals they measure for neuromotor robot-assisted rehabilitation. A comprehensive classification of sensors was proposed, distinguishing between specific and non-specific parameters. The classification criteria address essential factors such as the type of sensors, the data they measure, their usability, ergonomics, and their overall impact on personalized treatment. In addition, a framework designed to collect and utilize relevant data for the optimal rehabilitation process efficiently is proposed. The proposed classifications aim to identify a set of key variables that can be used as a building block for a dynamic framework tailored for personalized treatments, thereby enhancing the effectiveness of patient-centered procedures in rehabilitation.

Advances in acute respiratory distress syndrome: focusing on heterogeneity, pathophysiology, and therapeutic strategies

In recent years, the incidence of acute respiratory distress syndrome (ARDS) has been gradually increasing. Despite advances in supportive care, ARDS remains a significant cause of morbidity and mortality in critically ill patients. ARDS is characterized by acute hypoxaemic respiratory failure with diffuse pulmonary inflammation and bilateral edema due to excessive alveolocapillary permeability in patients with non-cardiogenic pulmonary diseases. Over the past seven decades, our understanding of the pathology and clinical characteristics of ARDS has evolved significantly, yet it remains an area of active research and discovery. ARDS is highly heterogeneous, including diverse pathological causes, clinical presentations, and treatment responses, presenting a significant challenge for clinicians and researchers. In this review, we comprehensively discuss the latest advancements in ARDS research, focusing on its heterogeneity, pathophysiological mechanisms, and emerging therapeutic approaches, such as cellular therapy, immunotherapy, and targeted therapy. Moreover, we also examine the pathological characteristics of COVID-19-related ARDS and discuss the corresponding therapeutic approaches. In the face of challenges posed by ARDS heterogeneity, recent advancements offer hope for improved patient outcomes. Further research is essential to translate these findings into effective clinical interventions and personalized treatment approaches for ARDS, ultimately leading to better outcomes for patients suffering from ARDS.

Predictive validity of the sequential organ failure assessment score for mortality in patients with acute respiratory distress syndrome in Vietnam

Evaluating the prognosis of ARDS patients using grading systems can enhance treatment decisions. This retrospective observational study evaluated the predictive accuracy of the SOFA score, APACHE II score, SpO2/FiO2 ratio, and PaO2/FiO2 ratio for mortality in ARDS patients in Vietnam. The study included 335 adult ARDS patients admitted to a central hospital from August 2015 to August 2023. Among them, 66.9% were male, the median age was 55 years, and 61.5% died in the hospital. The SOFA (AUROC: 0.651) and APACHE II scores (AUROC: 0.693) showed poor discriminatory ability for hospital mortality. The SpO2/FiO2 (AUROC: 0.595) and PaO2/FiO2 ratios (AUROC: 0.595) also displayed poor discriminatory ability. In multivariable analyses, after adjusting for the same set of confounding variables, the APACHE II score (adjusted OR: 1.152), SpO2/FiO2 ratio (adjusted OR: 0.985), and PaO2/FiO2 ratio (adjusted OR: 0.989) were independently associated with hospital mortality. Although the SOFA score (adjusted OR: 1.132) indicated a potential association with hospital mortality, it did not reach statistical significance (p = 0.081). However, a SOFA score of ≥ 10 emerged as an independent predictor (adjusted OR: 3.398) of hospital mortality. These findings emphasize the need for further studies to develop more accurate scoring systems for predicting outcomes in ARDS patients.

Clinical Performance of Spo2/Fio2 and Pao2/Fio2 Ratio in Mechanically Ventilated Acute Respiratory Distress Syndrome Patients: A Retrospective Study

OBJECTIVES

The present study aims to evaluate the severity classification of acute respiratory distress syndrome (ARDS) in mechanically ventilated patients according to peripheral oxygen saturation by pulse oximetry (Spo2)/Fio2 ratio compared with Pao2/Fio2 ratio and the relationship between Spo2/Fio2 ratio and venous admixture.

DESIGN

Retrospective observational study.

SETTING

Medical-surgical ICU.

PATIENTS

A cohort of 258 mechanically ventilated patients with ARDS already enrolled in previous studies.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Gas exchange, Spo2, and respiratory mechanics were measured on ICU admission and during the positive end-expiratory pressure (PEEP) trial. Radiological data from CTs were used to compute lung recruitability and to assess different lung compartments. A nonlinear association was found between Spo2/Fio2 and Pao2/Fio2. Considering the possible confounding factors of the pulse oximeter on the relationship between Spo2/Fio2 and Pao2/Fio2 ratio, arterial pH, and Paco2 had no effect. Spo2/Fio2 and Pao2/Fio2 ratio demonstrated a moderate agreement in classifying ARDS severity (intraclass correlation coefficient = 0.63). Between the correspondent classes according to Spo2/Fio2 vs. Pao2/Fio2 ratio-derived severity classifications, there was no difference in terms of respiratory mechanics, gas exchange, lung radiological characteristics and mortality in ICU, and within two levels of PEEP. A Spo2/Fio2 ratio less than 235 was able to detect 89% of patients with a venous admixture greater than 20%, similarly to a Pao2/Fio2 ratio less than 200.

CONCLUSIONS

Spo2/Fio2 ratio can detect oxygenation impairment and classify ARDS severity similarly to Pao2/Fio2 ratio in a more rapid and handy way, even during a PEEP trial. However, our results may not be applicable to different patient populations; in fact, the pulse oximeter is merely a monitoring device and the information should be personalized by the physician on the patient's characteristics and conditions.

Machine learning-based forecast of Helmet-CPAP therapy failure in Acute Respiratory Distress Syndrome patients

BACKGROUND AND OBJECTIVE

Helmet-Continuous Positive Airway Pressure (H-CPAP) is a non-invasive respiratory support that is used for the treatment of Acute Respiratory Distress Syndrome (ARDS), a severe medical condition diagnosed when symptoms like profound hypoxemia, pulmonary opacities on radiography, or unexplained respiratory failure are present. It can be classified as mild, moderate or severe. H-CPAP therapy is recommended as the initial treatment approach for mild ARDS. Even though the efficacy of H-CPAP in managing patients with moderate-to-severe hypoxemia remains unclear, its use has increased for these cases in response to the emergence of the COVID-19 Pandemic. Using the electronic medical records (EMR) from the Pulmonology Department of Vimercate Hospital, in this study we develop and evaluate a Machine Learning (ML) system able to predict the failure of H-CPAP therapy on ARDS patients.

METHODS

The Vimercate Hospital EMR provides demographic information, blood tests, and vital parameters of all hospitalizations of patients who are treated with H-CPAP and diagnosed with ARDS. This data is used to create a dataset of 622 records and 38 features, with 70%-30% split between training and test sets. Different ML models such as SVM, XGBoost, Neural Network, Random Forest, and Logistic Regression are iteratively trained in a cross-validation fashion. We also apply a feature selection algorithm to improve predictions quality and reduce the number of features.

RESULTS AND CONCLUSIONS

The SVM and Neural Network models proved to be the most effective, achieving final accuracies of 95.19% and 94.65%, respectively. In terms of F1-score, the models scored 88.61% and 87.18%, respectively. Additionally, the SVM and XGBoost models performed well with a reduced number of features (23 and 13, respectively). The PaO2/FiO2 Ratio, C-Reactive Protein, and O2 Saturation resulted as the most important features, followed by Heartbeats, White Blood Cells, and D-Dimer, in accordance with the clinical scientific literature.

Acute respiratory distress syndrome (ARDS): from mechanistic insights to therapeutic strategies

Acute respiratory distress syndrome (ARDS) is a clinical syndrome of acute hypoxic respiratory failure caused by diffuse lung inflammation and edema. ARDS can be precipitated by intrapulmonary factors or extrapulmonary factors, which can lead to severe hypoxemia. Patients suffering from ARDS have high mortality rates, including a 28-day mortality rate of 34.8% and an overall in-hospital mortality rate of 40.0%. The pathophysiology of ARDS is complex and involves the activation and dysregulation of multiple overlapping and interacting pathways of systemic inflammation and coagulation, including the respiratory system, circulatory system, and immune system. In general, the treatment of inflammatory injuries is a coordinated process that involves the downregulation of proinflammatory pathways and the upregulation of anti-inflammatory pathways. Given the complexity of the underlying disease, treatment needs to be tailored to the problem. Hence, we discuss the pathogenesis and treatment methods of affected organs, including 2019 coronavirus disease (COVID-19)-related pneumonia, drowning, trauma, blood transfusion, severe acute pancreatitis, and sepsis. This review is intended to provide a new perspective concerning ARDS and offer novel insight into future therapeutic interventions.

Evaluating the impact of ESICM 2023 guidelines and the new global definition of ARDS on clinical outcomes: insights from MIMIC-IV cohort data

BACKGROUND

In 2023, the European Society of Intensive Care Medicine (ESICM) recommended updated criteria for acute respiratory distress syndrome (ARDS). In 2024, Matthay et al. updated the global ARDS definition in AJRCCM, titled "A New Global Definition of Acute Respiratory Distress Syndrome." However, the impact of this new definition on ARDS treatments is currently unknown.

OBJECTIVE

This study aims to determine the effect of the new ARDS definition on patients with hypoxemic respiratory failure and study the heterogeneity of patients in the new definition to guide treatment.

METHODS

Clinical consultation data from the Medical Information Mart for Intensive Care IV database were extracted using Structured Query Language based on the PostgreSQL tool (version 10.0). Data were analyzed using Python (version 3.9) and the deep learning framework Pytorch. Kaplan-Meier survival analysis was used to compare survival between the old and new definitions. A hierarchical clustering approach was applied to identify potential ARDS clinical subtypes.

RESULTS

The new definition diagnosed ARDS earlier and included individuals with lower mortality rates compared with the Berlin definition. Patients meeting the new definition but not the Berlin criteria exhibited a favorable response to non-invasive ventilation strategies (p = 0.009). The XGBoost classifier, trained to predict subphenotypes, achieved an AUC of 0.88 ± 0.02 on the training set. Additionally, mortality was significantly associated with patients with hypoxemia compared with survivors, particularly regarding respiratory parameters. Easily accessible metrics, such as respiratory rate and urea nitrogen (BUN), can help diagnose ARDS in high-risk populations in resource-limited settings.

CONCLUSIONS

The new ARDS definition offers advantages in earlier detection, more accurate grading, and more precise diagnosis in resource-limited settings compared with the Berlin definition. This study also established a robust prediction model for early ARDS identification, improving the patient prognosis and reducing the mortality rate.

Use of the oxygen reserve index/FiO2 as a non-invasive index to estimate venous admixture in anesthetized dogs

The oxygen reserve index (ORi) is a novel, non-invasive parameter that estimates arterial oxygen partial pressure (PaO2) during hyperoxia when the fraction of inspired oxygen (FiO2) is elevated. This study aimed to assess the utility of the ORi/FiO2 ratio as an index for quantifying F-shunt, serving as an estimate of venous admixture. Anesthetic records were reviewed from 44 dogs undergoing general anesthesia and requiring arterial catheterization. ORi was measured via a CO-oximeter using a probe on the tongue. Paired measurements of PaO2, obtained by blood gas analysis, and ORi were taken at various FiO2 levels to achieve an ORi between 0 and 1. Venous admixture was quantified by F-shunt. Spearman's correlation coefficient assessed the relationship between ORi/FiO2 and F-shunt. Youden's index identified the optimal cut-off point to predict a physiological F-shunt (≤ 10%). A total of 77 paired observations were collected, revealing a moderate negative correlation between F-shunt and ORi/FiO2 (rho = -0.59, p < 0.001). An ORi/FiO2 cut-off of 1.2 demonstrated 80% sensitivity for identifying dogs with an F-shunt ≤10%, with a ROC curve area above 80%. However, the index was less effective at distinguishing dogs with higher shunt fractions. The ORi/FiO2 index identifies dogs with low F-shunt during anesthesia with strong sensitivity and predictive accuracy, potentially ruling out the occurrence of ventilation-perfusion inequality. However, it cannot replace blood gas analysis for quantifying venous admixture.

Definitions of Acute Respiratory Distress Syndrome: Present Recommendations and Challenges

Acute respiratory distress syndrome (ARDS) is an acute inflammatory process resulting in diffuse lung injury precipitated by an underlying risk factor. However, current definitions may pose barriers to the accurate diagnosis of this syndrome. These include changes in risk factors and associated disease evolution of ARDS, changes in contemporary clinical practice, and access to diagnostic tools required to diagnose ARDS in resource-limited settings. A consensus conference has proposed changes for an expanded global definition of ARDS. In this review article, we review challenges in defining ARDS and present recommendations of the global definition of ARDS.

Motion resistance in peripheral oxygen saturation monitoring using Biolight Analog SpO2 compared to Masimo SpO2: a non-inferiority study

BACKGROUND

Pulse oximeters are vital for assessing blood oxygen levels but can produce inaccurate readings during patient motion, leading to false alarms and alarm fatigue. Analog SpO2 Technology, which uses analog waveforms to filter motion artifacts, may improve accuracy compared to digital sensors. However, the effectiveness of this technology in reducing false alarms in clinical settings remains unclear. This study assesses and compares the motion resistance of Analog SpO2 Technology of two devices in the market.

METHODS

Thirty healthy adults underwent controlled experiments (Control, Linear Motion, Angular Motion) using two pulse oximeters. Linear Motion tested hand displacement impact, while Angular Motion involved rhythmic hand motions at 120 bpm and 160 bpm.

RESULTS

Both devices performed similarly in Control, with no disruptions. In Linear Motion, mild disruptions occurred, but no significant differences in SpO2 readings or alarms. Angular Motion at 120 bpm showed stability with no alarms. At 160 bpm, Device B (Biolight Analog SpO2) had fewer technical alarms but more SpO2 alarms than Device A (Masimo Analog SpO2).

CONCLUSIONS

Analog SpO2 exhibited motion resistance under static, linear and continuous waving angular motion up to 120 bpm and 160 bpm, but alarms occurred at 160 bpm with continuous tapping angular motion. These findings signify non-inferiority of either device in clinical settings. Further studies should include patients with cardiovascular and/or respiratory diseases.

TRIAL REGISTRATION

The study was submitted to and approved by the Biolight Ethics Committee (S0723), and written informed consent from all participants was obtained.

Impact of mechanical power on ICU mortality in ventilated critically ill patients: a retrospective study with continuous real-life data

BACKGROUND

Over the past decade, numerous studies on potential factors contributing to ventilation-induced lung injury have been carried out. Mechanical power has been pointed out as the parameter that encloses all ventilation-induced lung injury-contributing factors. However, studies conducted to date provide data regarding mechanical power during the early hours of mechanical ventilation that may not accurately reflect the impact of power throughout the period of mechanical ventilatory support on intensive care unit mortality.

METHODS

Retrospective observational study conducted at a single center in Spain. Patients admitted to the intensive care unit, > o = 18 years of age, and ventilated for over 24 h were included. We extracted the mechanical power values throughout the entire mechanical ventilation in controlled modes period from the clinical information system every 2 min. First, we calculate the cutoff-point for mechanical power beyond which there was a greater change in the probability of death. After, the sum of time values above the safe cut-off point was calculated to obtain the value in hours. We analyzed if the number of hours the patient was under ventilation with a mechanical power above the safe threshold was associated with intensive care unit mortality, invasive mechanical ventilation days, and intensive care unit length of stay. We repeated the analysis in different subgroups based on the degree of hypoxemia and in patients with SARS CoV-2 pneumonia.

RESULTS

The cut-off point of mechanical power at with there is a higher increase in intensive care unit mortality was 18 J/min. The greater the number of hours patients were under mechanical power > 18 J/min the higher the intensive care unit mortality in all the study population, in patients with SARS CoV-2 pneumonia and in mild to moderate hypoxemic respiratory failure. The risk of death in the intensive care unit increases 0.1% for each hour with mechanical power exceeding 18 J/min. The number of hours with mechanical power > 18 J/min also affected the days of invasive mechanical ventilation and intensive care unit length of stay.

CONCLUSIONS

The number of hours with mechanical power > 18 J/min is associated with mortality in the intensive care unit in critically ill patients. Continuous monitoring of mechanical power in controlled modes using an automated clinical information system could alert the clinician to this risk.

Pulse oximetry in pediatric care: Balancing advantages and limitations

BACKGROUND

Pulse oximetry has become a cornerstone technology in healthcare, providing non-invasive monitoring of oxygen saturation levels and pulse rate. Despite its widespread use, the technology has inherent limitations and challenges that must be addressed to ensure accurate and reliable patient care.

AIM

To comprehensively evaluate the advantages, limitations, and challenges of pulse oximetry in clinical practice, as well as to propose recommendations for optimizing its use.

METHODS

A systematic literature review was conducted to identify studies related to pulse oximetry and its applications in various clinical settings. Relevant articles were selected based on predefined inclusion and exclusion criteria, and data were synthesized to provide a comprehensive overview of the topic.

RESULTS

Pulse oximetry offers numerous advantages, including non-invasiveness, real-time feedback, portability, and cost-effectiveness. However, several limitations and challenges were identified, including motion artifacts, poor peripheral perfusion, ambient light interference, and patient-specific factors such as skin pigmentation and hemoglobin variants. Recommendations for optimizing pulse oximetry use include technological advancements, education and training initiatives, quality assurance protocols, and interdisciplinary collaboration.

CONCLUSION

Pulse oximetry is crucial in modern healthcare, offering invaluable insights into patients' oxygenation status. Despite its limitations, pulse oximetry remains an indispensable tool for monitoring patients in diverse clinical settings. By implementing the recommendations outlined in this review, healthcare providers can enhance the effectiveness, accessibility, and safety of pulse oximetry monitoring, ultimately improving patient outcomes and quality of care.

Low-cost and convenient screening of disease using analysis of physical measurements and recordings

In recent years, there has been substantial work in low-cost medical diagnostics based on the physical manifestations of disease. This is due to advancements in data analysis techniques and classification algorithms and the increased availability of computing power through smart devices. Smartphones and their ability to interface with simple sensors such as inertial measurement units (IMUs), microphones, piezoelectric sensors, etc., or with convenient attachments such as lenses have revolutionized the ability collect medically relevant data easily. Even if the data has relatively low resolution or signal to noise ratio, newer algorithms have made it possible to identify disease with this data. Many low-cost diagnostic tools have been created in medical fields spanning from neurology to dermatology to obstetrics. These tools are particularly useful in low-resource areas where access to expensive diagnostic equipment may not be possible. The ultimate goal would be the creation of a "diagnostic toolkit" consisting of a smartphone and a set of sensors and attachments that can be used to screen for a wide set of diseases in a community healthcare setting. However, there are a few concerns that still need to be overcome in low-cost diagnostics: lack of incentives to bring these devices to market, algorithmic bias, "black box" nature of the algorithms, and data storage/transfer concerns.

Early Operative Risk Assessment Using the Modified Mannheim Peritonitis Index in Patients With Generalised Peritonitis at a Tertiary Hospital in Abuja, Nigeria

Introduction The use of validated prognostic scoring tools in resource-poor environments has been hampered by the cost of procuring and maintaining devices, such as arterial blood gas analysers, to measure critical physiological derangements. Attempts need to be made to adapt these applicable risk stratification tools so they can be easily adopted in developing countries like Nigeria.  Aim This study assessed the usefulness of a modified Mannheim peritonitis index (mMPI) as a risk stratification tool in predicting surgical outcomes in managing patients with generalised peritonitis in Abuja, Nigeria. Methods This was a prospective study of consecutive adult patients managed for generalised peritonitis at a tertiary hospital in Abuja over 12 months. Approval numbers NHA/EC/037/2019 and AF/013/17/110/1514 were ascribed to the project by the Institute Review Board Committee (IBR) of the National Hospital Abuja (NHA) and the National Postgraduate Medical College of Nigeria. The MPI was modified using respiratory rate and suboptimal percentage oxygen saturation (SpO2). Patient characteristics and treatment outcomes obtained were entered into a structured proforma, checked, and analysed using IBM SPSS Statistics for Windows, Version 25.0 (Released 2017; IBM Corp., Armonk, New York, United States). The threshold score of the modified MPI and the accuracy, sensitivity, and specificity were derived from the receiver operating characteristic (ROC) curve analysis and its coordinates. The level of statistical significance was set at a p-value of <0.05. Results There were 49 patients with generalised peritonitis during the study period with a male-to-female ratio of 2.5:1. The commonest cause of peritonitis in this study was penetrating abdominal injury (n=15, 30.6%), followed by complicated appendicitis (n=12, 24.5%). This study's mortality and morbidity rates were 14.3% and 63.3%, respectively. On the ROC curve, the modified MPI best predicts mortality at a threshold score point of ≥26 (accuracy of 79.4%, sensitivity of 85.7%, specificity of 61.9%, p=0.013) and morbidity at a threshold score of ≥23 (accuracy of 78.4%, sensitivity of 77.4%, specificity of 72.2%, p=0.001).  Conclusion The modified MPI can be used as a risk assessment tool to predict postoperative outcomes in adult patients operated on for generalised peritonitis within 30 days of operative intervention at Abuja. This modification may be helpful in low-resource centres with limited access to arterial blood gas analysers. However, the original MPI might be a more accurate tool.

The Impact of Common Variations in Sequential Organ Failure Assessment Score Calculation on Sepsis Measurement Using Sepsis-3 Criteria: A Retrospective Analysis Using Electronic Health Record Data

OBJECTIVES

To assess the impact of different methods of calculating Sequential Organ Failure Assessment (SOFA) scores using electronic health record data on the incidence, outcomes, agreement, and predictive validity of Sepsis-3 criteria.

DESIGN

Retrospective observational study.

SETTING

Five Massachusetts hospitals.

PATIENTS

Hospitalized adults, 2015 to 2022.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We defined sepsis as a suspected infection (culture obtained and antibiotic administered) with a concurrent increase in SOFA score by greater than or equal to 2 points (Sepsis-3 criteria). Our reference SOFA implementation strategy imputed normal values for missing data, used Pa o2 /F io2 ratios for respiratory scores, and assumed normal baseline SOFA scores for community-onset sepsis. We then implemented SOFA scores using different missing data imputation strategies (averaging worst values from preceding and following days vs. carrying forward nonmissing values), imputing respiratory scores using Sp o2 /F io2 ratios, and incorporating comorbidities and prehospital laboratory data into baseline SOFA scores. Among 1,064,459 hospitalizations, 297,512 (27.9%) had suspected infection and 141,052 (13.3%) had sepsis with an in-hospital mortality rate of 10.3% using the reference SOFA method. The percentage of patients missing SOFA components for at least 1 day in the infection window was highest for Pa o2 /F io2 ratios (98.6%), followed by Sp o2 /F io2 ratios (73.5%), bilirubin (68.5%), and Glasgow Coma Scale scores (57.2%). Different missing data imputation strategies yielded near-perfect agreement in identifying sepsis (kappa 0.99). However, using Sp o2 /F io2 imputations yielded higher sepsis incidence (18.3%), lower mortality (8.1%), and slightly lower predictive validity for mortality (area under the receiver operating curves [AUROC] 0.76 vs. 0.78). For community-onset sepsis, incorporating comorbidities and historical laboratory data into baseline SOFA score estimates yielded lower sepsis incidence (6.9% vs. 11.6%), higher mortality (13.4% vs. 9.6%), and higher predictive validity (AUROC 0.79 vs. 0.75) relative to the reference SOFA implementation.

CONCLUSIONS

Common variations in calculating respiratory and baseline SOFA scores, but not in handling missing data, lead to substantial differences in observed incidence, mortality, agreement, and predictive validity of Sepsis-3 criteria.

High-flow nasal cannula oxygen therapy in seven cats with respiratory failure

CASE SERIES SUMMARY

This case series describes seven cats that were treated with high-flow nasal cannula oxygen therapy (HFNOT). Seven cats were prospectively (n = 5) or retrospectively (n = 2) included from three veterinary university referral centers between March 2020 and September 2023. Data on signalment, medical history, clinical and diagnostic findings, treatment administered, response to HFNOT and outcomes were recorded. All cats included in this case series failed to respond to oxygen cage or flow-by oxygen therapy and were subsequently transitioned to HFNOT. After this transition, these cats demonstrated a marked improvement in respiratory parameters, including respiratory rate, effort and oxygen saturation measured by pulse oximetry, within 1 h of initiating HFNOT. All cats tolerated HFNOT well without any complications.

RELEVANCE AND NOVEL INFORMATION

There is limited literature reporting the use of HFNOT in feline patients. This is the first case series in the literature of HFNOT utilized as an advanced oxygen delivery method for feline respiratory failure. This case series indicates that HFNOT improves oxygenation in feline patients that fail to respond to conventional oxygen therapy.

C-Reactive Protein as a Predictor of Severe Respiratory Complications in Measles

Background and Objectives: Even though measles is easily prevented by vaccination, infection outbreaks are not rare. Infection carries a great risk for pulmonary complications, which are sometimes hard to predict, especially in a group of outpatients. This study aims to evaluate the association between serum CRP changes and the severity of respiratory complications in the group of inpatients treated for measles. Materials and Methods: A total of 207 patients admitted and treated at the Clinic for Infectious Diseases, University Clinical Center, Nis, for measles infection were included in the analysis. The data collected from the patients' medical records included demographic characteristics, disease duration, blood and serum biochemical analysis, general measles-associated symptoms, and disease outcome. Results: Results of the study revealed that there are almost no differences in the clinical presentation of patients with measles and those complicated with pneumonia. The examined CRP changes are found to correlate with the observable degree of pneumonia; however, they do not correspond to the changes visible in chest X-rays. Conclusions: CRP changes in the serum of patients with measles with mild clinical pictures could be a potential predictor for the development of some pulmonary complications.

Recent advances in cardiorespiratory monitoring in acute respiratory distress syndrome patients

BACKGROUND

Recent advances on cardiorespiratory monitoring applied in ARDS patients undergoing invasive mechanical ventilation and noninvasive ventilatory support are available in the literature and may have potential prognostic implication in ARDS treatment.

MAIN BODY

The measurement of oxygen saturation by pulse oximetry is a valid, low-cost, noninvasive alternative for assessing arterial oxygenation. Caution must be taken in patients with darker skin pigmentation, who may experience a greater incidence of occult hypoxemia. Dead space surrogates, which are easy to calculate, have important prognostic implications. The mechanical power, which can be automatically computed by intensive care ventilators, is an important parameter correlated with ventilator-induced lung injury and outcome. In patients undergoing noninvasive ventilatory support, the use of esophageal pressure can measure inspiratory effort, avoiding possible delays in endotracheal intubation. Fluid responsiveness can also be evaluated using dynamic indices in patients ventilated at low tidal volumes (< 8 mL/kg). In patients ventilated at high levels of positive end expiratory pressure (PEEP), the PEEP test represents a valid alternative to passive leg raising. There is growing evidence on alternative parameters for evaluating fluid responsiveness, such as central venous oxygen saturation variations, inferior vena cava diameter variations and capillary refill time.

CONCLUSION

Careful cardiorespiratory monitoring in patients affected by ARDS is crucial to improve prognosis and to tailor treatment via mechanical ventilatory support.

Post-pandemic acute respiratory distress syndrome: A New Global Definition with extension to lower-resource regions

Acute respiratory distress syndrome (ARDS), first described in 1967, is characterized by acute respiratory failure causing profound hypoxemia, decreased pulmonary compliance, and bilateral CXR infiltrates. After several descriptions, the Berlin definition was adopted in 2012, which established three categories of severity according to hypoxemia (mild, moderate and severe), specified temporal aspects for diagnosis, and incorporated the use of non-invasive ventilation. The COVID-19 pandemic led to changes in ARDS management, focusing on continuous monitoring of oxygenation and on utilization of high-flow oxygen therapy and lung ultrasound. In 2021, a New Global Definition based on the Berlin definition of ARDS was proposed, which included a category for non-intubated patients, considered the use of SpO2, and established no particular requirement for oxygenation support in regions with limited resources. Although debates persist, the continuous evolution seeks to adapt to clinical and epidemiological needs, and to the search of personalized treatments.

Prediction of acute lung injury assessed by chest computed tomography, oxygen saturation/fraction of inspired oxygen ratio, and serum lactate dehydrogenase in patients with COVID-19

INTRODUCTION

In treating acute hypoxemic respiratory failure (AHRF) caused by coronavirus disease 2019 (COVID-19), clinicians choose respiratory therapies such as low-flow nasal cannula oxygenation, high-flow nasal cannula oxygenation, or mechanical ventilation after assessment of the patient's condition. Chest computed tomography (CT) imaging contributes significantly to diagnosing COVID-19 pneumonia. However, the costs and potential harm to patients from radiation exposure need to be considered. This study was performed to predict the quantitative extent of COVID-19 acute lung injury using clinical indicators such as an oxygenation index and blood test results.

METHODS

We analyzed data from 192 patients with COVID-19 AHRF. Multiple logistic regression was used to determine correlations between the lung infiltration volume (LIV) and other pathophysiological or biochemical laboratory parameters.

RESULTS

Among 13 clinical parameters, we identified the oxygen saturation/fraction of inspired oxygen ratio (SF ratio) and serum lactate dehydrogenase (LD) concentration as factors associated with the LIV. In the binary classification of an LIV of ≥20 % or not and with the borderline LD = 2.2 × [SF ratio]-182.4, the accuracy, precision, diagnostic odds ratio, and area under the summary receiver operating characteristic curve were 0.828, 0.818, 23.400, and 0.870, respectively.

CONCLUSIONS

These data suggest that acute lung injury due to COVID-19 pneumonia can be estimated using the SF ratio and LD concentration without a CT scan. These findings may provide significant clinical benefit by allowing clinicians to predict acute lung injury levels using simple, minimally invasive assessment of oxygenation capacity and biochemical blood tests.

Enhancing Neonatal Care: The Vital Role of Pulse Oximetry in the Early Screening of Critical Congenital Heart Diseases and Respiratory Diseases in Rural Areas

Background Pulse oximetry screening (POS) is acknowledged globally as a noninvasive method to detect critical congenital heart diseases (CCHDs) and respiratory illnesses. However, its value for early diagnosis and treatment remains unrecognized in many hospitals with limited resources around the world. This study aimed to evaluate POS's application in CCHDs, persistent pulmonary hypertension (PPHN), and respiratory distress syndrome (RDS) for early diagnosis and its influence on clinical procedures in rural areas. Methods This prospective observational study included all eligible newborn infants in the regional neonatal unit of a community healthcare center. Their peripheral oxygen saturation was assessed at <24 hours and >24 hours after birth, in the right upper limb and either lower limb. An oxygen saturation of <95% or >3% difference between pre-ductal and post-ductal circulations was considered abnormal. All neonates with abnormal oxygen saturations at >24 hours after birth were subjected to another POS test within two hours of the last test. If the oxygen saturation was still abnormal, it was considered a positive POS test. The POS results were classified as oxygen saturation abnormal (<90%), abnormal (90-94%), and normal (≥95%). All neonates with a positive POS test were referred for echocardiography. Results Overall, 440 infants had documented POS results. A total of 65 (14.77%) infants had a positive POS test result, out of which 39 (8.86%) cases were diagnosed on further evaluation. Four neonates had CCHD (positive predictive value (PPV) = 6.15%), 26 had RDS (PPV = 40%), and nine had PPHN (PPV = 13.85%). Without any further delay, the doctor directed them all to a more advanced facility. Conclusion Our research showed that, in large-scale clinical settings, the addition of pulse oximetry to routine cardiac auscultation could be a reliable and feasible method to screen newborns for CCHD, PPHN, and RDS early on. Our research underscores the importance of implementing routine POS to detect CCHD, RDS, and PPHN in clinical practice.

A Game Changer for ARDS? Unraveling the Potential of the SF Ratio

Rangappa R. A Game Changer for ARDS? Unraveling the Potential of the SF Ratio. Indian J Crit Care Med 2024;28(3):191-192.

ERS International Congress 2023: highlights from the Respiratory Intensive Care Assembly

Early career members of Assembly 2 (Respiratory Intensive Care) attended the 2023 European Respiratory Society International Congress in Milan, Italy. The conference covered acute and chronic respiratory failure. Sessions of interest to our assembly members and to those interested in respiratory critical care are summarised in this article and include the latest updates in respiratory intensive care, in particular acute respiratory distress syndrome and mechanical ventilation.

The Development of a Measuring System for Intraoral SpO2

Blood oxygen saturation (SpO2) is an essential indicator of a patient's general condition. However, conventional measurement methods have some issues such as time delay and interference by ambient light. Improved measurement methods must be developed, and there are no reports on intraoral measurements of SpO2 using wearable devices. Therefore, we aimed to establish an intraoral SpO2 measurement method for the first time. Twelve healthy adults participated in this study. The following steps were taken: (1) to identify the optimal measurement location, mid-perfusion index (PI) values were measured at six places on the mucosa of the maxilla, (2) to validate the optimal measurement pressure, PI values were obtained at different pressures, and (3) using the proposed mouthpiece device, SpO2 values in the oral cavity and on the finger were analyzed during breath-holding. The highest PI values were observed in the palatal gingiva of the maxillary canine teeth, with high PI values at pressures ranging from 0.3 to 0.8 N. In addition, changes in SpO2 were detected approximately 7 s faster in the oral cavity than those on the finger, which is attributed to their proximity to the heart. This study demonstrates the advantage of the oral cavity for acquiring biological information using a novel device.

A New Global Definition of Acute Respiratory Distress Syndrome

Background: Since publication of the 2012 Berlin definition of acute respiratory distress syndrome (ARDS), several developments have supported the need for an expansion of the definition, including the use of high-flow nasal oxygen, the expansion of the use of pulse oximetry in place of arterial blood gases, the use of ultrasound for chest imaging, and the need for applicability in resource-limited settings. Methods: A consensus conference of 32 critical care ARDS experts was convened, had six virtual meetings (June 2021 to March 2022), and subsequently obtained input from members of several critical care societies. The goal was to develop a definition that would 1) identify patients with the currently accepted conceptual framework for ARDS, 2) facilitate rapid ARDS diagnosis for clinical care and research, 3) be applicable in resource-limited settings, 4) be useful for testing specific therapies, and 5) be practical for communication to patients and caregivers. Results: The committee made four main recommendations: 1) include high-flow nasal oxygen with a minimum flow rate of ⩾30 L/min; 2) use PaO2:FiO2 ⩽ 300 mm Hg or oxygen saturation as measured by pulse oximetry SpO2:FiO2 ⩽ 315 (if oxygen saturation as measured by pulse oximetry is ⩽97%) to identify hypoxemia; 3) retain bilateral opacities for imaging criteria but add ultrasound as an imaging modality, especially in resource-limited areas; and 4) in resource-limited settings, do not require positive end-expiratory pressure, oxygen flow rate, or specific respiratory support devices. Conclusions: We propose a new global definition of ARDS that builds on the Berlin definition. The recommendations also identify areas for future research, including the need for prospective assessments of the feasibility, reliability, and prognostic validity of the proposed global definition.

Categorizing Acute Respiratory Distress Syndrome with Different Severities by Oxygen Saturation Index

The oxygen saturation index (OSI), defined by FIO2/SpO2 multiplied by the mean airway pressure, has been reported to exceed the Berlin definition in predicting the mortality of acute respiratory distress syndrome (ARDS). The OSI has served as an alternative to the Berlin definition in categorizing pediatric ARDS. However, the use of the OSI for the stratification of adult ARDS has not been reported. A total of 379 invasively ventilated adult ARDS patients were retrospectively studied. The ARDS patients were classified into three groups by their incidence rate of mortality: mild (OSI < 14.69), moderate (14.69 < OSI < 23.08) and severe (OSI > 23.08). OSI-based categorization was highly correlated with the Berlin definition by a Kendall's tau of 0.578 (p < 0.001). The Kaplan-Meier curves of the three OSI-based groups were significantly different (p < 0.001). By the Berlin definition, the hazard ratio for 28-day mortality was 0.58 (0.33-1.05) and 0.95 (0.55-1.67) for the moderate and severe groups, respectively (compared to the mild group). In contrast, the corresponding hazard ratio was 1.01 (0.69-1.47) and 2.39 (1.71-3.35) for the moderate and severe groups defined by the OSI. By multivariate analysis, OSI-based severe ARDS was independently associated with 28-D or 90-D mortality. In conclusion, we report the first OSI-based stratification for adult ARDS and find that it serves well as an alternative to the Berlin definition.

Survey of Transfer Learning Approaches in the Machine Learning of Digital Health Sensing Data

Machine learning and digital health sensing data have led to numerous research achievements aimed at improving digital health technology. However, using machine learning in digital health poses challenges related to data availability, such as incomplete, unstructured, and fragmented data, as well as issues related to data privacy, security, and data format standardization. Furthermore, there is a risk of bias and discrimination in machine learning models. Thus, developing an accurate prediction model from scratch can be an expensive and complicated task that often requires extensive experiments and complex computations. Transfer learning methods have emerged as a feasible solution to address these issues by transferring knowledge from a previously trained task to develop high-performance prediction models for a new task. This survey paper provides a comprehensive study of the effectiveness of transfer learning for digital health applications to enhance the accuracy and efficiency of diagnoses and prognoses, as well as to improve healthcare services. The first part of this survey paper presents and discusses the most common digital health sensing technologies as valuable data resources for machine learning applications, including transfer learning. The second part discusses the meaning of transfer learning, clarifying the categories and types of knowledge transfer. It also explains transfer learning methods and strategies, and their role in addressing the challenges in developing accurate machine learning models, specifically on digital health sensing data. These methods include feature extraction, fine-tuning, domain adaptation, multitask learning, federated learning, and few-/single-/zero-shot learning. This survey paper highlights the key features of each transfer learning method and strategy, and discusses the limitations and challenges of using transfer learning for digital health applications. Overall, this paper is a comprehensive survey of transfer learning methods on digital health sensing data which aims to inspire researchers to gain knowledge of transfer learning approaches and their applications in digital health, enhance the current transfer learning approaches in digital health, develop new transfer learning strategies to overcome the current limitations, and apply them to a variety of digital health technologies.

Racial and ethnic minority participants in clinical trials of acute respiratory distress syndrome

PURPOSE

There is growing interest in improving the inclusiveness of racial and ethnic minority participants in trials of acute respiratory distress syndrome (ARDS). With our study we aimed to examine temporal trends of representation and mortality of racial and ethnic minority participants in randomized controlled trials of ARDS.

METHODS

We performed a secondary analysis of eight ARDS Network and PETAL Network therapeutic clinical trials, published between 2000 and 2019. We classified race/ethnicity into "White", "Black", "Hispanic", or "Other" (including Asian, American Indian or Alaskan Native, Native Hawaiian, or other Pacific Islander participants).

RESULTS

Of 5375 participants with ARDS, 1634 (30.4%) were Black, Hispanic, or Other race participants. Representation of racial and ethnic minority participants in trials did not change significantly over time (p = 0.257). However, among participants with moderate to severe ARDS (i.e., partial pressure of arterial oxygen to fraction of inspired oxygen ratio < 150), the difference in mortality between racial and ethnic minority participants and White participants decreased over time. In the five most recent trials, including 2923 participants with ARDS, there were no statistically significant differences in mortality between racial/ethnic groups, even after adjusting for potential confounders. In these five most recent trials, mortality was 31% for White, 31.9% for Black, 30.3% for Hispanic, and 37.1% for Other race participants (p = 0.633).

CONCLUSION

Representation of racial and ethnic minority participants in ARDS trials from North America, published between 2000 and 2019, did not change over time. Black and Hispanic participants with ARDS may have similar mortality as White participants within trials.

Comparative analysis of signal accuracy of three SpO2 monitors during motion and low perfusion conditions

To compare pulse oximetry performance during simulated conditions of motion and low perfusion in three commercially available devices: GE HealthCare CARESCAPE ONE TruSignal SpO2 Parameter, Masimo RADICAL-7 and Medtronic Nellcor PM1000N. After IRB approval, 28 healthy adult volunteers were randomly assigned to the motion group (N = 14) or low perfusion (N = 14) group. Pulse oximeters were placed on the test and control hands using random assignment of digits 2-5. Each subject served as their own control through the series of repeated pair-wise measurements. Reference co-oximetry oxyhemoglobin (SaO2) measurements from the radial artery were also obtained in the motion group. SpO2 readings were compared between the test and control hands in both groups and to SaO2 measurements in the motion group. Accuracy was assessed through testing of accuracy root-mean squared (ARMS) and mean bias. In the simulated motion test group the overall Accuracy Root Mean Square (ARMS) versus SaO2 was 1.88 (GE), 1.79 (Masimo) and 2.40 (Nellcor), with overall mean bias of - 0.21 (Masimo), 0.45 (GE), and 0.78 (Nellcor). In the motion hand, ARMS versus SaO2 was 2.45 (GE), 3.19 (Masimo) and 4.15 (Nellcor), with overall mean bias of - 0.75 (Masimo), - 0.01 (GE), and 0.04 (Nellcor). In the low perfusion test group, ARMS versus the control hand SpO2 for low PI was 3.24 (GE), 3.48 (Nellcor) and 4.76 (Masimo), with overall bias measurements of - 0.53 (Nellcor), 0.96 (GE) and 1.76 (Masimo). Experimental results for all tested devices met pulse oximetry regulatory and testing standards requirements. Overall, SpO2 device performance across the three devices in this study was similar under both motion and low perfusion conditions. SpO2 measurement accuracy degraded for all three devices during motion as compared to non-motion. Accuracy also degraded during normal to low, very low, or ultra low perfusion and was more pronounced compared to the changes observed during simulated motion. While some statistically significant differences in individual measurements were found, the clinical relevance of these differences requires further study.

Correlation and Prognostic Significance of Oxygenation Indices in Invasively Ventilated Adults (OXIVA-CARDS) with COVID-19-associated ARDS: A Retrospective Study

Background

Oxygenation index [OI = (MAP × FiO2 × 100)/PaO2] assesses the severity of hypoxic respiratory failure. Oxygen saturation index [OSI = (MAP × FiO2 × 100)/SpO2] is a noninvasive method to assesses the severity of hypoxic respiratory failure. Conventionally used PaO2/FiO2 (P/F) ratio to measure the severity of ARDS requires arterial blood gas (ABG) sampling. It tenders limited prognostic information mandating the need for better markers. Oxygenation index (needs arterial sampling) and OSI (a noninvasive method) are substitutes to provide mortality information in ARDS patients. We evaluated the correlation between P/F, OI, and OSI in invasively ventilated COVID-19 ARDS patients (C-ARDS) and looked at its relationship with mortality.

Patients and methods

A retrospective study of invasively ventilated C-ARDS >18 years of age managed in COVID ICU. Ventilator settings (FiO2, mean airway pressure), pulse oximetry (SpO2), and ABG values (PaO2) were simultaneously noted at the time of sample collection. Patient outcomes (alive and deceased) were documented. Differences in parameters between survivors and nonsurvivors were assessed using independent sample t-test. Receiver operating characteristic (ROC) analysis with Youden's index was used to identify cutoff values to determine survival.

Results

A total of 1557 measurements for 203 patients were collected over the maximum duration of 21 days after ventilation. About 147 (72.4%) were males and 56 (27.6%) were females. On day one of ventilation, 161 (79.3%) had P/F ratio <200, 28 (13.8%) had P/F ratio between 200 and 300, and 14 (6.9%) had P/F ratio >300. There was a linear relationship between P/F ratio and OSI (r = -0.671), P/F and OI (r = -0.753), and OSI and OI (r = 0.893) (p < 0.001). After natural log transform, the correlation between these factors became stronger [P/F ratio and OSI (r = -0.797), PF and OI (r = -0.949), and OSI and OI (r = 0.902) (p < 0.001)]. About 74 (36.5%) patients survived. Survivors had significantly higher P/F ratio as compared with nonsurvivors (p < 0.05). Oxygen saturation index and OI were significantly lower in survivors as compared with nonsurvivors. Based on day-1 reading, a higher OSI (AUC = 0.719, 95% CI = 0.648-0.790) and OI (AUC = 0.752. 95% CI = 0.684-0.819) significantly can predict mortality. On the other hand, a higher P/F ratio can predict survival (AUC = 0.734, 95% CI = 0.664-0.805). P/F ratio of 160 on day 1 can predict survival. Oxygen saturation index values above 10.4% and OI above 13.5% were the cutoff derived for day 1 values to predict mortality.

Conclusion

Noninvasive OSI can be used to assess the severity of hypoxic respiratory failure in C-ARDS without arterial access in resource-limited settings. Oxygen saturation index can noninvasively provide prognostic information in invasively ventilated C-ARDS patients.

How to cite this article

Vadi S, Suthar D, Sanwalka N. Correlation and Prognostic Significance of Oxygenation Indices in Invasively Ventilated Adults (OXIVA-CARDS) with COVID-19-associated ARDS: A Retrospective Study. Indian J Crit Care Med 2023;27(11):801-805.

High-Flow Nasal Cannula oxygen therapy in COVID-19: retrospective analysis of clinical outcomes - single center experience

Background

High-Flow Nasal Cannula (HFNC) oxygen therapy emerged as the therapy of choice in COVID-19-related pneumonia and moderate to severe acute hypoxemic respiratory failure (AHRF). HFNC oxygen therapy in COVID-19 has been recommended based its use to treat AHRF of other etiologies, and studies on assessing outcomes in COVID-19 patients are highly needed. This study aimed to examine outcomes in COVID-19 patients with pneumonia and severe AHRF treated with HFNC.

Materials and methods

The study included 235 COVID-19 patients with pneumonia treated with HFNC. Data extracted from medical records included demographic characteristics, comorbidities, laboratory parameters, clinical and oxygenation status, clinical complications, as well as the length of hospital stay. Patients were segregated into two groups based on their oxygen therapy needs: HDU group, those who exclusively required HFNC and ICU group, those whose oxygen therapy needed to be escalated at some point of hospital stay. The primary outcome was the need for respiratory support escalation (noninvasive or invasive mechanical ventilation) and the secondary outcome was the in-hospital all-cause mortality.

Results

The primary outcome was met in 113 (48%) of patients. The overall mortality was 70%, significantly higher in the ICU group [102 (90.2%) vs. 62 (50.1%), p < 0.001]. The rate of intrahospital infections was significantly higher in the ICU group while there were no significant differences in the length of hospital stay between the groups. The ICU group exhibited significant increases in D-dimer, NLR, and NEWS values, accompanied by a significant decrease in the SaO2/FiO2 ratio. The multivariable COX proportional regression analysis identified malignancy, higher levels of 4C Mortality Score and NEWS2 as significant predictors of mortality.

Conclusion

High-Flow Nasal Cannula oxygen therapy is a safe type of respiratory support in patients with COVID-19 pneumonia and acute hypoxemic respiratory failure with significantly less possibility for emergence of intrahospital infections. In 52% of patients, HFNC was successful in treating AHRF in COVID-19 patients. Overall, mortality in COVID-19 pneumonia with AHRF is still very high, especially in patients treated with noninvasive/invasive mechanical ventilation.

[Saturation index and fraction of inspired oxygen as a predictor in COVID-19]

Background

Coronavirus disease leads to silent hypoxia, ARDS, and organ failure. The saturation and fraction of inspired oxygen have been related to the degree of lung damage, can be considered as a monitoring tool for lung function during hospitalization and a predictor of mortality in patients with pneumonia by COVID-19.

Objective

To evaluate the usefulness of the oxygen saturation index and fraction of inspired oxygen as a predictor of mortality in patients with COVID-19 pneumonia.

Material and methods

A retrospective, longitudinal, analytical study. Files of eligible patients with a diagnosis of SARS-CoV-2 pneumonia were admitted to HGR No.2, complete file, recording of oxygen saturation and inspired fraction of oxygen, were included. Patients dependent on supplemental oxygen, who did not require supplemental oxygen during their hospitalization, incomplete records, patients who have died from non-pulmonary causes, were excluded.

Results

A sample of 175 files with a diagnosis of pneumonia with SARS-CoV-2 was obtained. A logistic regression model was performed including age over 60 years BE of 2.68, with CI (1.09-6.5), DM2 with a BE of 2.35 with CI (0.99-5.59), HTA with a BE of 0.80, with CI (0.32-2.02), SAFI index less than 310 with a BE of 6.63, with a CI (2.64-16.65), endotracheal intubation with a BE 48.43, and a CI (2.64-16.65).

Conclusion

The SpO2/Fio2 index can be used for continuous monitoring of lung function in patients with COVID-19 pneumonia, in an accessible, easy and economical way. A relationship with mortality was obtained in patients with SpO2/FiO2 less than 310 associated with other factors.

Everything About Pulse Oximetry-Part 2: Clinical Applications, Portable/Wearable Pulse Oximeters, Remote Patient Monitoring, and Recent Advances

Purpose: Pulse oximetry is widely used in healthcare settings for both screening and continuous monitoring. In this article, it was aimed to review some aspects of pulse oximetry including clinical applications, portable devices, and recent advances in detail. Materials and Methods: The international and national reliable sources were used in the literature review for critical data analysis. A total of 31 articles including 19 prospective comparative clinical studies, 9 reviews, 1 meta-analysis, 1 retrospective study, and 1 experimental study were used for preparation of this part of the review. Results: In this part of the article, clinical applications of pulse oximeters, portable/wearable pulse oximeters, remote patient monitoring, and recent advances were all reviewed in detail. Conclusion: Pulse oximetry is a widely used and reliable noninvasive technique that provides useful information about blood oxygenation in individuals. This technique can guide oxygen therapy, reduce the occurrence of hypoxemia, and decrease the frequency of admissions to the intensive care unit, as well as arterial blood gas sampling. New multiwaveform sensors and advanced signal processing techniques can differentiate between different types of hemoglobin and may be useful for continuous measurement of total hemoglobin, as well as for detecting and providing information on blood loss and cardiac output.

ESICM guidelines on acute respiratory distress syndrome: definition, phenotyping and respiratory support strategies

The aim of these guidelines is to update the 2017 clinical practice guideline (CPG) of the European Society of Intensive Care Medicine (ESICM). The scope of this CPG is limited to adult patients and to non-pharmacological respiratory support strategies across different aspects of acute respiratory distress syndrome (ARDS), including ARDS due to coronavirus disease 2019 (COVID-19). These guidelines were formulated by an international panel of clinical experts, one methodologist and patients' representatives on behalf of the ESICM. The review was conducted in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement recommendations. We followed the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach to assess the certainty of evidence and grade recommendations and the quality of reporting of each study based on the EQUATOR (Enhancing the QUAlity and Transparency Of health Research) network guidelines. The CPG addressed 21 questions and formulates 21 recommendations on the following domains: (1) definition; (2) phenotyping, and respiratory support strategies including (3) high-flow nasal cannula oxygen (HFNO); (4) non-invasive ventilation (NIV); (5) tidal volume setting; (6) positive end-expiratory pressure (PEEP) and recruitment maneuvers (RM); (7) prone positioning; (8) neuromuscular blockade, and (9) extracorporeal life support (ECLS). In addition, the CPG includes expert opinion on clinical practice and identifies the areas of future research.

Oxygen saturation targets for adults with acute hypoxemia in low and lower-middle income countries: a scoping review with analysis of contextual factors

Knowing the target oxygen saturation (SpO2) range that results in the best outcomes for acutely hypoxemic adults is important for clinical care, training, and research in low-income and lower-middle income countries (collectively LMICs). The evidence we have for SpO2 targets emanates from high-income countries (HICs), and therefore may miss important contextual factors for LMIC settings. Furthermore, the evidence from HICs is mixed, amplifying the importance of specific circumstances. For this literature review and analysis, we considered SpO2 targets used in previous trials, international and national society guidelines, and direct trial evidence comparing outcomes using different SpO2 ranges (all from HICs). We also considered contextual factors, including emerging data on pulse oximetry performance in different skin pigmentation ranges, the risk of depleting oxygen resources in LMIC settings, the lack of access to arterial blood gases that necessitates consideration of the subpopulation of hypoxemic patients who are also hypercapnic, and the impact of altitude on median SpO2 values. This process of integrating prior study protocols, society guidelines, available evidence, and contextual factors is potentially useful for the development of other clinical guidelines for LMIC settings. We suggest that a goal SpO2 range of 90-94% is reasonable, using high-performing pulse oximeters. Answering context-specific research questions, such as an optimal SpO2 target range in LMIC contexts, is critical for advancing equity in clinical outcomes globally.

Guideline-based management of acute respiratory failure and acute respiratory distress syndrome

Acute respiratory failure (ARF) is defined by acute and progressive hypoxemia caused by various cardiorespiratory or systemic diseases in previously healthy patients. Among ARF, acute respiratory distress syndrome (ARDS) is a serious condition with bilateral lung infiltration, which develops secondary to a variety of underlying conditions, diseases, or injuries. This review summarizes the current standard of care for ARF and ARDS based on current major guidelines in this field. When administering fluid in patients with ARF, particularly ARDS, restrictive strategies need to be considered in patients without shock or multiple organ dysfunction. Regarding oxygenation targets, avoiding excessive hyperoxemia and hypoxemia is probably a reasonable choice. As a result of the rapid spread and accumulation of evidence for high-flow nasal cannula oxygenation, it is now weakly recommended for the respiratory management of ARF in general and even for initial management of ARDS. Noninvasive positive pressure ventilation is also weakly recommended for the management of certain ARF conditions and as initial management of ARDS. Low tidal volume ventilation is now weakly recommended for all patients with ARF and strongly recommended for patients with ARDS. Limiting plateau pressure and high-level PEEP are weakly recommended for moderate-to-severe ARDS. Prone position ventilation with prolonged hours is weakly to strongly recommended for moderate-to-severe ARDS. In patients with COVID-19, ventilatory management is essentially the same as for ARF and ARDS, but awake prone positioning may be considered. In addition to standard care, treatment optimization and individualization, as well as the introduction of exploratory treatment, should be considered as appropriate. As a single pathogen, such as SARS-CoV-2, exhibits a wide variety of pathologies and lung dysfunction, ventilatory management for ARF and ARDS may be better tailored according to the respiratory physiologic status of individual patients rather than the causal or underlying diseases and conditions.

Oxygenation thresholds for invasive ventilation in hypoxemic respiratory failure: a target trial emulation in two cohorts

BACKGROUND

The optimal thresholds for the initiation of invasive ventilation in patients with hypoxemic respiratory failure are unknown. Using the saturation-to-inspired oxygen ratio (SF), we compared lower versus higher hypoxemia severity thresholds for initiating invasive ventilation.

METHODS

This target trial emulation included patients from the Medical Information Mart for Intensive Care (MIMIC-IV, 2008-2019) and the Amsterdam University Medical Centers (AmsterdamUMCdb, 2003-2016) databases admitted to intensive care and receiving inspired oxygen fraction ≥ 0.4 via non-rebreather mask, noninvasive ventilation, or high-flow nasal cannula. We compared the effect of using invasive ventilation initiation thresholds of SF < 110, < 98, and < 88 on 28-day mortality. MIMIC-IV was used for the primary analysis and AmsterdamUMCdb for the secondary analysis. We obtained posterior means and 95% credible intervals (CrI) with nonparametric Bayesian G-computation.

RESULTS

We studied 3,357 patients in the primary analysis. For invasive ventilation initiation thresholds SF < 110, SF < 98, and SF < 88, the predicted 28-day probabilities of invasive ventilation were 72%, 47%, and 19%. Predicted 28-day mortality was lowest with threshold SF < 110 (22.2%, CrI 19.2 to 25.0), compared to SF < 98 (absolute risk increase 1.6%, CrI 0.6 to 2.6) or SF < 88 (absolute risk increase 3.5%, CrI 1.4 to 5.4). In the secondary analysis (1,279 patients), the predicted 28-day probability of invasive ventilation was 50% for initiation threshold SF < 110, 28% for SF < 98, and 19% for SF < 88. In contrast with the primary analysis, predicted mortality was highest with threshold SF < 110 (14.6%, CrI 7.7 to 22.3), compared to SF < 98 (absolute risk decrease 0.5%, CrI 0.0 to 0.9) or SF < 88 (absolute risk decrease 1.9%, CrI 0.9 to 2.8).

CONCLUSION

Initiating invasive ventilation at lower hypoxemia severity will increase the rate of invasive ventilation, but this can either increase or decrease the expected mortality, with the direction of effect likely depending on baseline mortality risk and clinical context.

The Sequential Organ Failure Assessment (SOFA) Score: has the time come for an update?

The Sequential Organ Failure Assessment (SOFA) score was developed more than 25 years ago to provide a simple method of assessing and monitoring organ dysfunction in critically ill patients. Changes in clinical practice over the last few decades, with new interventions and a greater focus on non-invasive monitoring systems, mean it is time to update the SOFA score. As a first step in this process, we propose some possible new variables that could be included in a SOFA 2.0. By so doing, we hope to stimulate debate and discussion to move toward a new, properly validated score that will be fit for modern practice.

Usefulness and limitations of the acute respiratory distress syndrome definitions in non-intubated patients. A narrative review

According to the Berlin Definition of acute respiratory distress syndrome (ARDS), a positive end-expiratory pressure (PEEP) of at least 5 cmH₂O is required to diagnose and grade ARDS. While the Berlin consensus statement specifically acknowledges the role of non-invasive ventilation (NIV) in mild ARDS, this stratification has traditionally presumed a mechanically ventilated patient in the context of moderate to severe ARDS. This may not accurately reflect today's reality of clinical respiratory care. NIV and high-flow nasal cannula oxygen therapy (HFNO) have been used for managing of severe forms of acute hypoxemic respiratory failure with growing frequency, including in patients showing pathophysiological signs of ARDS. This became especially relevant during the COVID-19 pandemic. The levels of PEEP achieved with HFNO have been particularly controversial, and the exact FiO₂ it achieves is subject to variability. Pinpointing the presence of ARDS in patients receiving HNFO and the severity in those receiving NIV therefore remains methodically problematic. This narrative review highlights the evolution of the ARDS definition in the context of non-invasive ventilatory support and provides an overview of the parallel development of definitions and ventilatory management of ARDS. It summarizes the methodology applied in clinical trials to classify ARDS in non-intubated patients and the respective consequences on treatment. As ARDS severity has significant therapeutic and prognostic consequences, and earlier treatment in non-intubated patients may be beneficial, closing this knowledge gap may ultimately be a relevant step to improve comparability in clinical trial design and outcomes.