A clinical case of prolonged CPAP ventilation in a patient with COVID-19-associated pneumonia

Non-invasive ventilation (NIV) via a mask to maintain a constant positive airway pressure (CPAP mask) is the method of choice for the treatment of pulmonary disorders in severe COVID-19-associated pneumonia. Nowadays, there are no studies which had shown the effectiveness of the ROX-index in predicting the efficacy of NIV in patients with acute hypoxic respiratory failure (AHRF). This clinical case describes our experience of effective use of ROX-index in patients with AHRF because of coronavirus dis-ease, SARS-CoV-2-associated, who underwent non-invasive lung ventilation through CPAP mask. © 2022. The Authors.

Impact of High-Flow Nasal Cannula Use in Subjects With COVID-19 ARDS at High Altitudes: Clinical Presentation and Prognostic Factors.

BACKGROUND: High-flow nasal cannula (HFNC) reduces the need for intubation in adult subject with acute respiratory failure. Changes in hypobaric hypoxemia have not been studied for subject with an HFNC in ICUs at altitudes > 2,600 m above sea level. In this study, we investigated the efficacy of HFNC treatment in subjects with COVID-19 at high altitudes. We hypothesized that progressive hypoxemia and the increase in breathing frequency associated with COVID-19 in high altitudes affect the success of HFNC therapy and may also influence the performance of the traditionally used predictors of success and failure. METHODS: This was a prospective cohort study of subjects >18 y with a confirmed diagnosis of COVID-19-induced ARDS requiring HFNC who were admitted to the ICU. Subjects were followed up during the 28 d of HFNC treatment or until failure. RESULTS: One hundred and eight subjects were enrolled. At admission to the ICU, FIO2 delivery between 0.5-0.8 (odds ratio 0.38 [95% CI 0.17-0.84]) was associated with a better response to HFNC therapy than oxygen delivery on admission between 0.8-1.0 (odds ratio 3.58 [95% CI 1.56-8.22]). This relationship continued during follow-ups at 2, 6, 12, and 24 h, with a progressive increase in the risk of failure (odds ratio 24 h 13.99 [95% CI 4.32-45.26]). A new cutoff for the ratio of oxygen saturation (ROX) index (ROX ≥ 4.88) after 24 h of HFNC administration was demonstrated to be the best predictor of success (odds ratio 11.0 [95% CI 3.3-47.0]). CONCLUSIONS: High-altitude subjects treated with HFNC for COVID-19 showed a high risk of respiratory failure and progressive hypoxemia when FIO2 requirements were > 0.8 after 24 h of treatment. In these subjects, personalized management should include continuous monitoring of individual clinical conditions (such as oxygenation indices, with cutoffs adapted to those corresponding to high-altitude cities).

Predictive Accuracy of the Breathing Frequency-Ratio of Oxygen Saturation Index for Re-Intubation in Mechanically Ventilated Subjects With COVID-19.

BACKGROUND: Several studies have suggested that high-flow nasal cannula (HFNC) is useful for respiratory support after extubation in subjects with COVID-19 pneumonia, whereas 18.2% subsequently needed to undergo re-intubation. This study aimed to evaluate whether the breathing frequency (f)-ratio of oxygen saturation (ROX) index, which has been shown to be useful for predicting future intubation, is also useful for re-intubation in subjects with COVID-19. METHODS: We retrospectively analyzed mechanically ventilated subjects with COVID-19 who underwent HFNC therapy after extubation at 4 participating hospitals between January 2020-May 2022. We evaluated the predictive accuracy of ROX at 0, 1, and 2 h for re-intubation until ICU discharge and compared the area under the receiver operating characteristic (ROC) curve of the ROX index with those of f and SpO2 /FIO2 . RESULTS: Among the 248 subjects with COVID-19 pneumonia, 44 who underwent HFNC therapy after extubation were included. A total of 32 subjects without re-intubation were classified into the HFNC success group, and 12 with re-intubation were classified into the failure group. The overall trend that the area under the ROC curve of the ROX index was greater than that of the f and SaO2 /FIO2 was observed, although there was no statistical significance at any time point. The ROX index at 0 h, at the cutoff point of < 7.44, showed a sensitivity and specificity of 0.42 and 0.97, respectively. A trend of positive correlation between the time until re-intubation and ROX index at each time point was observed. CONCLUSIONS: The ROX index in the early phase of HFNC therapy after extubation was useful for predicting re-intubation with high accuracy in mechanically ventilated subjects with COVID-19. We may need close observation for subjects with < 7.44 ROX index just after extubation because of their high risk for re-intubation.

Diaphragmatic Ultrasound Predictors of High-Flow Nasal Cannula Therapeutic Failure in Critically Ill Patients With SARS-CoV-2 Pneumonia.

OBJECTIVES: High flow nasal cannula (HFNC) is frequently used in patients with acute respiratory failure, but there is limited evidence regarding predictors of therapeutic failure. The objective of this study was to assess diaphragmatic ultrasound criteria as predictors of failure to HFNC, defined as the need for orotracheal intubation or death. METHODS: Prospective cohort study including adult patients consecutively admitted to the critical care unit, from July 24 to October 20, 2020, with respiratory failure secondary to SARS-CoV-2 pneumonia who required HFNC. After 12 hours of HFNC initiation we measured ROX index (ratio of SpO2 /FiO2 to respiratory rate), excursion and diaphragmatic contraction speed (diaphragmatic excursion/inspiratory time) by ultrasound, both in supine and prone position. RESULTS: In total, 41 patients were analyzed, 25 succeeded and 16 failed HFNC therapy. At 12 hours, patients who succeeded HFNC therapy presented higher ROX index in supine position (9.8 [9.1-15.6] versus 5.4 [3.9-6.8], P < .01), and higher PaO2 /FiO2 ratio (186 [135-236] versus 117 [103-162] mmHg, P = .03). To predict therapeutic failure, the supine diaphragmatic contraction speed presented sensitivity of 89% and a specificity of 57%, while the ROX index presented a sensitivity of 92.8% and a specificity of 75%. CONCLUSIONS: Diaphragmatic contraction speed by ultrasound emerges as a diagnostic complement to clinical tools to predict HFNC success. Future studies should confirm these results.

Lung ultrasound scoring system vs ROX index as a predictor for progression to the invasive mechanical ventilation in COVID-19 patients

Background: During the outbreak of the highly contagious Coronavirus disease 19 (COVID19), rapid and simple prognostic tools were needed to support clinical decisions and predict the need of invasive mechanical ventilation. the ROX index, and the lung ultrasound score (LUSS) were proposed to objectively predict patient prognosis in addition to the subjective clinical assessment Aim: This study aimed to compare lung ultrasound score with ROX index in predicting the need of invasive ventilation in COVID-19 patients requiring advanced oxygen therapy. Patients and Methods: We studied 50 patients with severe COVID-19 pneumonia in the intensive care unit in the isolated area at Kasr Al-Ainy hospital. Complete Medical history, physical examination and laboratory investigations were obtained on admission. All patients underwent bedside lung ultrasonography scan and LUSS was calculated at the 2nd and the 12th hours, also ROX index was calculated at the 2nd, 6th and 12th hours from initiating the advanced oxygen therapy. Result(s): From a total of fifty patients with COVID-19, 56.0% were males, with mean age of 65.98 + 11.68 years, and mortality rate was 68%. The optimal cut off value of the ROX index at (2, 6, 12 hour) is (2.495, 2.675, 3.06) respectively, (p <0.001) with sensitivity 90.9% and specificity 76.5% at the 12 hour. Also the optimal cut off point of LUSS is 25.50 (p <0.001) with sensitivity 93.9% and specificity 88.2% for prediction of the invasive mechanical ventilation. Conclusion and recommendations: The study concluded that LUSS is more sensitive in predicting the need of invasive mechanical ventilation than ROX index.Copyright © 2023, Codon Publications. All rights reserved.

Prognostic Performance of Bedside Lung Ultrasound Score (LUSS) and ROX Index in Hypoxemic Respiratory Failure Due to COVID-19.

Background: Noninvasive ventilation, mainly helmet CPAP, was widely used during the COVID-19 pandemic, even outside of intensive care units. Both the ROX index and the LUS score (LUSS) have been proposed as tools to predict negative outcomes in patients with hypoxemia treated with noninvasive ventilation (NIV) outside of ICUs. We aim to evaluate whether the combination of LUSS with the ROX index improves the predictive performance of these indices in patients with hypoxemia due to COVID-19 pneumonia, treated with NIV outside of ICUs. Methods: This is a monocentric prospective observational study conducted at the university teaching hospital Fondazione IRCCS San Gerardo dei Tintori (Monza, Italy) from February to April 2021. LUSS and ROX were collected at the same time in noninvasively ventilated patients outside of the ICU. An LUS exam was performed by 3 emergency medicine attending physicians with at least 5 years' experience in point-of-care ultrasonography using a 12-zone system. To evaluate the accuracy of the prognostic indices in predicting a composite outcome (endotracheal intubation and mortality), ROC curves were used. A logistic multivariable model was used to explore the predictors of the composite outcome of endotracheal intubation and in-hospital mortality. An unadjusted Kaplan-Meier analysis was used to explore the association with the composite outcome of survival without invasive mechanical ventilation at the 30-day follow-up by stratifying the 3 indices by their best cut-offs. Results: A total of 79 patients were included in the statistical analysis and stratified into 2 groups based on the presence of a negative outcome, which was reported in 24 patients out of 79 (30%). A great proportion of patients (66 patients-84%) were treated with helmet CPAP. All three indices (LUSS, ROX and LUSS/ROX) were independently associated with negative outcomes in the multivariable analyses. Although the comparison between the AUROC of LUSS or ROX versus LUSS/ROX did not reveal a statistically significant difference, we observed a trend toward a higher accuracy for predicting negative outcomes using the LUSS/ROX index as compared to using LUSS. With the Kaplan-Maier approach, all three indices stratified by the best cut-off reported a significant association with the outcome of 30-day survival without mechanical ventilation. Conclusions: A multimodal noninvasive approach that combines ultrasound (i.e., LUSS) and a bedside clinical evaluation (i.e., the ROX index) may help clinicians to predict outcomes and to identify patients who would benefit the most from invasive respiratory support.

Choice of respiratory therapy for COVID-19 patients with acute hypoxemic respiratory failure: a retrospective case series study.

Background: In the treatment of acute hypoxemic respiratory failure (AHRF) due to coronavirus 2019 (COVID-19), physicians choose respiratory management ranging from low-flow oxygen therapy to more invasive methods, depending on the severity of the patient's symptoms. Recently, the ratio of oxygen saturation (ROX) index has been proposed as a clinical indicator to support the decision for either high-flow nasal cannulation (HFNC) or mechanical ventilation (MV). However, the reported cut-off value of the ROX index ranges widely from 2.7 to 5.9. The objective of this study was to identify indices to achieve empirical physician decisions for MV initiation, providing insights to shorten the delay from HFNC to MV. We retrospectively analyzed the ROX index 6 hours after initiating HFNC and lung infiltration volume (LIV) calculated from chest computed tomography (CT) images in COVID-19 patients with AHRF. Methods: We retrospectively analyzed the data for 59 COVID-19 patients with AHRF in our facility to determine the cut-off value of the ROX index for respiratory therapeutic decisions and the significance of radiological evaluation of pneumonia severity. The physicians chose either HFNC or MV, and the outcomes were retrospectively analyzed using the ROX index for initiating HFNC. LIV was calculated using chest CT images at admission. Results: Among the 59 patients who required high-flow oxygen therapy with HFNC at admission, 24 were later transitioned to MV; the remaining 35 patients recovered. Four of the 24 patients in the MV group died, and the ROX index values of these patients were 9.8, 7.3, 5.4, and 3.0, respectively. These index values indicated that the ROX index of half of the patients who died was higher than the reported cut-off values of the ROX index, which range from 2.7-5.99. The cut-off value of the ROX index 6 hours after the start of HFNC, which was used to classify the management of HFNC or MV as a physician's clinical decision, was approximately 6.1. The LIV cut-off value on chest CT between HFNC and MV was 35.5%. Using both the ROX index and LIV, the cut-off classifying HFNC or MV was obtained using the equation, LIV = 4.26 × (ROX index) + 7.89. The area under the receiver operating characteristic curve, as an evaluation metric of the classification, improved to 0.94 with a sensitivity of 0.79 and specificity of 0.91 using both the ROX index and LIV. Conclusion: Physicians' empirical decisions associated with the choice of respiratory therapy for HFNC oxygen therapy or MV can be supported by the combination of the ROX index and the LIV index calculated from chest CT images.

Applicability of the ROX index in decision-making for hospitalization in COVID-19 patients: ROX index in the outpatient COVID-19 cases

Aim: Data on the outpatient follow-up of COVID-19 cases is still scarce. Also, the significance of the ROX index in decision-making for hospitalization in the ambulatory COVID-19 cases remains unknown. The aim of this study is to determine the general characteristics of COVID-19 patients treated as outpatients and to investigate whether the ROX index is applicable in hospitalization decisions. Material(s) and Method(s): This retrospective cohort study was conducted in confirmed adult COVID-19 cases between 15 October 2020 and 01 March 2021. A total of 5240 confirmed COVID-19 patients were included in the present study. Factors affecting hospitalization were investigated. Result(s): The study population was divided into two groups as those who require hospitalization (n=672) and those who did not (n=4568). The number of male patients and the mean age of the patients were significantly higher in hospitalized patients group (p=0.046, p<0.001). ROX index that was calculated at the home visit on the third day of disease was found significantly lower in the group of hospitalized patients (p<0.001). There was a significant correlation between ROX index and inflammatory biomarkers in the present study (p<0.001). The ROX index was found the most accurate parameter for decision-making for hospitalization in ambulatory COVID-19 patients (AUC=0.794 CI=0.773-0.814, p<0.001). Discussion(s): The ROX index can be a useful and objective clinical tool for decision making for hospitalization in the ambulatory COVID-19 cases.Copyright © 2022, Derman Medical Publishing. All rights reserved.

Predicting the successful application of high-flow nasal oxygen cannula in patients with COVID-19 respiratory failure: a retrospective analysis.

BACKGROUND: The right time of high-flow nasal cannulas (HFNCs) application in COVID-19 patients with acute respiratory failure remains uncertain. RESEARCH DESIGN AND METHODS: In this retrospective study, COVID-19-infected adult patients with hypoxemic respiratory failure were enrolled. Their baseline epidemiological data and respiratory failure related parameters, including the Ventilation in COVID-19 Estimation (VICE), and the ratio of oxygen saturation (ROX index), were recorded. The primary outcome measured was the 28-day mortality. RESULTS: A total of 69 patients were enrolled. Fifty-four (78%) patients who intubated and received invasive mechanical ventilatory (MV) support on day 1 were enrolled in the MV group. The remaining fifteen (22%) patients received HFNC initially (HFNC group), in which, ten (66%) patients were not intubated during hospitalization were belong to HFNC-success group and five (33%) of these patients were intubated later due to disease progression were attributed to HFNC-failure group. Compared with those in the MV group, those in the HFNC group had a lower mortality rate (6.7% vs. 40.7%, p = 0.0138). There were no differences in baseline characteristics among the two groups; however, the HFNC group had a lower VICE score (0.105 [0.049-0.269] vs. 0.260 [0.126-0.693], p = 0.0092) and higher ROX index (5.3 [5.1-10.7] vs. 4.3 [3.9-4.9], p = 0.0007) than the MV group. The ROX index was higher in the HFNC success group immediately before (p = 0.0136) and up to 12 hours of HFNC therapy than in the HFNC failure group. CONCLUSIONS: Early intubation may be considered in patients with a higher VICE score or a lower ROX index. The ROX score during HFNCs use can provide an early warning sign of treatment failure. Further investigations are warranted to confirm these results.

High flow nasal cannulas (HFNCs) were widely used in patients with COVID-19 infection related hypoxemic respiratory failure. However, there were concerns about its failure and related delayed intubation may be associated with a higher mortality rate. This retrospective study revealed patients with higher baseline disease severity and higher VICE scores may be treated with primary invasive mechanical ventilation. On the contrary, if their baseline VICE score is low and ROX index is high, HFNCs treatment might be safely applied initially. The trends of serial ROX index values during HFNC use could be a reliable periscope to predict the HFNC therapy outcome, therefore avoided delayed intubation.

Parasternal intercostal thickening at hospital admission: a promising indicator for mechanical ventilation risk in subjects with severe COVID-19.

We aimed to evaluate the ability of parasternal intercostal thickening fraction (PIC TF) to predict the need for mechanical ventilation, and survival in subjects with severe Coronavirus disease-2019 (COVID-19). This prospective observational study included adult subjects with severe COVID-19. The following data were collected within 12 h of admission: PIC TF, respiratory rate oxygenation index, [Formula: see text] ratio, chest CT, and acute physiology and chronic health evaluation II score. The ability of PIC TF to predict the need for ventilatory support (primary outcome) and a composite of invasive mechanical ventilation and/or 30-days mortality were performed using the area under the receiver operating characteristic (AUC) analysis. Multivariate analysis was done to identify the independent predictors for the outcomes. Fifty subjects were available for the final evaluation. The AUC (95% confidence interval [CI]) for the right and left PIC TF ability to predict the need for ventilator support was 0.94 (0.83-0.99), 0.94 (0.84-0.99), respectively, with a cut off value of > 8.3% and positive predictive value of 90-100%. The AUC for the right and left PIC TF to predict invasive mechanical ventilation and/or 30 days mortality was 0.95 (0.85-0.99) and 0.90 (0.78-0.97), respectively. In the multivariate analysis, only the PIC TF was found to independently predict invasive mechanical ventilation and/or 30-days mortality. In subjects with severe COVID-19, PIC TF of 8.3% can predict the need to ventilatory support with a positive predictive value of 90-100%. PIC TF is an independent risk factor for the need for invasive mechanical ventilation and/or 30-days mortality.

Application of machine learning approach in emergency department to support clinical decision making for SARS-CoV-2 infected patients.

To support physicians in clinical decision process on patients affected by Coronavirus Disease 2019 (COVID-19) in areas with a low vaccination rate, we devised and evaluated the performances of several machine learning (ML) classifiers fed with readily available clinical and laboratory data. Our observational retrospective study collected data from a cohort of 779 COVID-19 patients presenting to three hospitals of the Lazio-Abruzzo area (Italy). Based on a different selection of clinical and respiratory (ROX index and PaO2/FiO2 ratio) variables, we devised an AI-driven tool to predict safe discharge from ED, disease severity and mortality during hospitalization. To predict safe discharge our best classifier is an RF integrated with ROX index that reached AUC of 0.96. To predict disease severity the best classifier was an RF integrated with ROX index that reached an AUC of 0.91. For mortality prediction the best classifier was an RF integrated with ROX index, that reached an AUC of 0.91. The results obtained thanks to our algorithms are consistent with the scientific literature an accomplish significant performances to forecast safe discharge from ED and severe clinical course of COVID-19.

The value of ROX index in predicting the outcome of high flow nasal cannula: a systematic review and meta-analysis.

BACKGROUND: High flow nasal cannula (HFNC) therapy is widely employed in acute hypoxemic respiratory failure (AHRF) patients. However, the techniques for predicting HFNC outcome remain scarce. METHODS: PubMed, EMBASE, and Cochrane Library were searched until April 20, 2021. We included the studies that evaluated the potential predictive value of ROX (respiratory rate-oxygenation) index for HFNC outcome. This meta-analysis determined sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic score, diagnostic odds ratio (DOR), and pooled area under the summary receiver operating characteristic (SROC) curve. RESULTS: We assessed nine studies with 1933 patients, of which 745 patients experienced HFNC failure. This meta-analysis found that sensitivity, specificity, PLR, NLR, diagnostic score, and DOR of ROX index in predicting HFNC failure were 0.67 (95% CI 0.57-0.76), 0.72 (95% CI 0.65-0.78), 2.4 (95% CI 2.0-2.8), 0.46 (95% CI 0.37-0.58), 1.65(95% CI 1.37-1.93), and 5.0 (95% CI 4.0-7.0), respectively. In addition, SROC was 0.75 (95% CI 0.71-0.79). Besides, our subgroup analyses revealed that ROX index had higher sensitivity and specificity for predicting HFNC failure in COVID-19 patients, use the cut-off value > 5, and the acquisition time of other times after receiving HFNC had a greater sensitivity and specificity when compared to 6 h. CONCLUSIONS: This study demonstrated that ROX index could function as a novel potential marker to identify patients with a higher risk of HFNC failure. However, the prediction efficiency was moderate, and additional research is required to determine the optimal cut-off value and propel acquisition time of ROX index in the future. PROSPERO registration number: CRD42021240607.

Prognostication of COVID-19 patients using ROX index and CURB-65 score - A retrospective observational study.

Objectives: Coronavirus disease-2019 (COVID-19) disease has overwhelmed the healthcare infrastructure worldwide. The shortage of intensive care unit (ICU) beds leads to longer waiting times and higher mortality for patients. High crowding leads to an increase in mortality, length of hospital stays, and hospital costs for patients. Through an appropriate stratification of patients, rational allocation of the available hospital resources can be accomplished. Various scores for risk stratification of patients have been tried, but for a score to be useful at primary care level, it should be readily available at the bedside and be reproducible. ROX index and CURB-65 are simple bedside scores, requiring minimum equipment, and investigations to calculate. Methods: This retrospective, record-based study included adult patients who presented to the ED from May 1, 2020 to November 30, 2020 with confirmed COVID-19 infection. The patient's clinical and demographic details were obtained from the electronic medical records of the hospital. ROX index and CURB-65 score on ED arrival were calculated and correlated with the need for hospitalization and early (14-day) and late (28-day) mortality. Results: 842 patients were included in the study. The proportion of patients with mild, moderate and severe disease was 46.3%, 14.9%, and 38.8%, respectively. 55% patients required hospitalization. The 14-day mortality was 8.8% and the 28-day mortality was 20.7%. The AUROC of ROX index for predicting hospitalization was 0.924 (p < 0.001), for 14-day mortality was 0.909 (p < 0.001) and for 28-day mortality was 0.933 (p < 0.001). The AUROC of CURB-65 score for predicting hospitalization was 0.845 (p < 0.001), for 14-day mortality was 0.905 (p < 0.001) and for 28-day mortality was 0.902 (p < 0.001). The cut-off of ROX index for predicting hospitalization was ≤18.634 and for 14-day mortality was ≤14.122. Similar cut-off values for the CURB-65 score were ≥1 and ≥2, respectively. Conclusion: ROX index and CURB-65 scores are simple and inexpensive scores that can be efficiently utilised by primary care physicians for appropriate risk stratification of patients with COVID-19 infection.

Use of high-flow nasal cannula oxygen and risk factors for high-flow nasal cannula oxygen failure in critically-ill patients with COVID-19.

BACKGROUND: High-flow nasal oxygen therapy (HFNC) may be an attractive first-line ventilatory support in COVID-19 patients. However, HNFC use for the management of COVID-19 patients and risk factors for HFNC failure remain to be determined. METHODS: In this retrospective study, we included all consecutive COVID-19 patients admitted to our intensive care unit (ICU) in the first (Mars-May 2020) and second (August 2020- February 202) French pandemic waves. Patients with limitations for intubation were excluded. HFNC failure was defined as the need for intubation after ICU admission. The impact of HFNC use was analyzed in the whole cohort and after constructing a propensity score. Risk factors for HNFC failure were identified through a landmark time-dependent cause-specific Cox model. The ability of the 6-h ROX index to detect HFNC failure was assessed by generating receiver operating characteristic (ROC) curve. RESULTS: 200 patients were included: HFNC was used in 114(57%) patients, non-invasive ventilation in 25(12%) patients and 145(72%) patients were intubated with a median delay of 0 (0-2) days after ICU admission. Overall, 78(68%) patients had HFNC failure. Patients with HFNC failure had a higher ICU mortality rate (34 vs. 11%, p = 0.02) than those without. At landmark time of 48 and 72 h, SAPS-2 score, extent of CT-Scan abnormalities > 75% and HFNC duration (cause specific hazard ratio (CSH) = 0.11, 95% CI (0.04-0.28), per + 1 day, p < 0.001 at 48 h and CSH = 0.06, 95% CI (0.02-0.23), per + 1 day, p < 0.001 at 72 h) were associated with HFNC failure. The 6-h ROX index was lower in patients with HFNC failure but could not reliably predicted HFNC failure with an area under ROC curve of 0.65 (95% CI(0.52-0.78), p = 0.02). In the matched cohort, HFNC use was associated with a lower risk of intubation (CSH = 0.32, 95% CI (0.19-0.57), p < 0.001). CONCLUSIONS: In critically-ill COVID-19 patients, while HFNC use as first-line ventilatory support was associated with a lower risk of intubation, more than half of patients had HFNC failure. Risk factors for HFNC failure were SAPS-2 score and extent of CT-Scan abnormalities > 75%. The risk of HFNC failure could not be predicted by the 6-h ROX index but decreased after a 48-h HFNC duration.

Prediction of high-flow nasal cannula outcomes at the early phase using the modified respiratory rate oxygenation index.

BACKGROUND: This study was designed to explore the early predictive value of the respiratory rate oxygenation (ROX) index modified by PaO2 (mROX) in high-flow nasal cannula (HFNC) therapy in patients with acute hypoxemia respiratory failure (AHRF). METHOD: Seventy-five patients with AHRF treated with HFNC were retrospectively reviewed. Respiratory parameters at baseline and 2 h after HFNC initiation were analyzed. The predictive value of the ROX (ratio of pulse oximetry/FIO2 to respiratory rate) and mROX (ratio of arterial oxygen /FIO2 to respiratory rate) indices with two variations by adding heart rate to each index (ROX-HR and mROX-HR) was evaluated. RESULTS: HFNC therapy failed in 24 patients, who had significantly higher intensive care unit (ICU) mortality and longer ICU stay. Both the ROX and mROX indices at 2 h after HFNC initiation can predict the risk of intubation after HFNC. Two hours after HFNC initiation, the mROX index had a higher area under the receiver operating characteristic curve (AUROC) for predicting HFNC success than the ROX index. Besides, baseline mROX index of greater than 7.1 showed a specificity of 100% for HFNC success. CONCLUSION: The mROX index may be a suitable predictor of HFNC therapy outcomes at the early phase in patients with AHRF.

Early Prediction of High-Flow Oxygen Therapy Failure in COVID-19 Acute Hypoxemic Respiratory Failure: A Retrospective Study of Scores and Thresholds.

Background High-flow oxygen therapy (HFOT) has been widely used as an effective alternative to invasive mechanical ventilation (IMV) in some critically ill patients with COVID-19 pneumonia. This study aimed to compare different tools, including the respiratory rate and oxygenation (ROX) index, to predict HFOT failure in this setting. Methodology This single-center retrospective observational study was conducted from September to December 2020 and assessed COVID-19 patients who required HFOT as the first treatment at admission; HFOT failure was defined as IMV use. Prognostic scoring tools were as follows: the Sequential Organ Failure Assessment (SOFA), Acute Physiology And Chronic Health Evaluation (APACHE) II, and Simplified Acute Physiology Score (SAPS) III scores; C-reactive protein; lung consolidation percentage on chest CT; mean partial pressure of oxygen in arterial blood (PaO2)/fraction of inspired oxygen (FiO2) ratio; and ROX index and modified ROX index, calculated using PaO2 instead of blood oxygen saturation, within the first 24 hours after admission to the intensive care unit (ICU). These scores were analyzed using a multivariate Cox proportional hazard model; optimal cutoffs were computed using the R system for statistical computing. Results The study enrolled 52 patients, 31 (60%) of whom experienced HFOT failure. The best predictors of HFOT failure measured 24 hours after HFOT initiation were as follows: PaO2/FiO2 (threshold 123.6, sensitivity 87%, specificity 81%, hazard ratio [HR] 7.76, and 95% confidence interval [CI] 2.39-17.1); ROX index (threshold 5.63, sensitivity 68%, specificity 95%, HR 6.18, and 95% CI 2.54-13.4); and modified ROX index (threshold 4.94, sensitivity 81%, specificity 90%, HR 8.16, and 95% CI 3.16-21.5) (P < 0.001 for all). Conclusions Early assessment of the ROX index, modified ROX index, and PaO2/FiO2 ratio can adequately predict, with high accuracy, HFOT failure in COVID-19 patients. Because thresholds remain debated and are still not sufficiently validated, we advocate using them with caution for clinical decision-making in this context.

Factors Associated With Non-invasive Oxygen Therapy Failure in COVID-19 Pneumonia: A Single Center, Retrospective Study in a Tertiary Hospital in North India.

BACKGROUND: Non-invasive oxygen therapy (NIT) consists of high-flow nasal oxygen (HFNO) and continuous positive airway pressure (CPAP). NIT is routinely being used for the management of acute respiratory failure secondary to coronavirus disease-2019 (COVID-19) with variable outcomes. However, previously published studies show that NIT failure might delay endotracheal intubation and invasive mechanical ventilation and results in worse outcomes in patients with hypoxemic respiratory failure. Early prediction of failure of NIT, will help in early decision-making in initiating invasive mechanical ventilation. We retrospectively studied the predictors for NIT failure in patients with moderate to severe COVID-19. METHODS: Adult patients (>18 years) admitted to the intensive care unit (ICU) with moderate to severe COVID-19 ARDS and received NIT [HFNO and CPAP non-invasive ventilation (NIV)] were included in this study. Baseline clinical and laboratory data were collected retrospectively from the electronic hospital information system. NIT failure was defined as the need for invasive mechanical ventilation after the initiation of NIT in the ICU. Univariate and multivariate logistic regression analyses were used to find out the possible predictors of NIT failure. RESULTS: Out of 254 patients admitted to ICU, 127 patients were initiated NIT at admission to ICU. During the course of the ICU stay, 33 (26%) patients subsequently required invasive mechanical ventilation (NIT failure). Respiratory rate-oxygenation index (ROX index) of <2.97 at two hours and <3.63 at six hours of ICU admission predicted NIT failure in our cohort of patients with a high positive predictive value. CONCLUSION: Patient selection is crucial for successful NIT in COVID-19. Application of ROX index measured in the first six hours of ICU admission helps in the identification of patients at risk of NIT failure with moderate to severe COVID-19 ARDS.