Association between the ROX index and mortality in patients with acute hypoxemic respiratory failure: a retrospective cohort study.

BACKGROUND: Although ROX index is frequently used to assess the efficacy of high-flow nasal cannula treatment in acute hypoxemic respiratory failure (AHRF) patients, the relationship between the ROX index and the mortality remains unclear. Therefore, a retrospective cohort study was conducted to evaluate the ability of the ROX index to predict mortality risk in patients with AHRF. METHOD: Patients diagnosed with AHRF were extracted from the MIMIC-IV database and divided into four groups based on the ROX index quartiles. The primary outcome was 28-day mortality, while in-hospital mortality and follow-up mortality were secondary outcomes. To investigate the association between ROX index and mortality in AHRF patients, restricted cubic spline curve and COX proportional risk regression were utilized. RESULT: A non-linear association (L-shaped) has been observed between the ROX index and mortality rate. When the ROX index is below 8.28, there is a notable decline in the 28-day mortality risk of patients as the ROX index increases (HR per SD, 0.858 [95%CI 0.794-0.928] P < 0.001). When the ROX index is above 8.28, no significant association was found between the ROX index and 28-day mortality. In contrast to the Q1 group, the mortality rates in the Q2, Q3, and Q4 groups had a substantial reduction (Q1 vs. Q2: HR, 0.749 [0.590-0.950] P = 0.017; Q3: HR, 0.711 [0.558-0.906] P = 0.006; Q4: HR, 0.641 [0.495-0.830] P < 0.001). CONCLUSION: The ROX index serves as a valuable predictor of mortality risk in adult patients with AHRF, and that a lower ROX index is substantially associated with an increase in mortality.

Respiratory rate­oxygenation (ROX) index for predicting high-flow nasal cannula failure in patients with and without COVID-19.

BACKGROUND: The predictive value of the respiratory rate­oxygenation (ROX) index for a high-flow nasal cannula (HFNC) in patients with COVID-19 with acute hypoxemic respiratory failure (AHRF) may differ from patients without COVID-19 with AHRF, but these patients have not yet been compared. We compared the diagnostic accuracy of the ROX index for HFNC failure in patients with AHRF with and without COVID-19 during acute emergency department (ED) visits. METHODS: We performed a retrospective analysis of patients with AHRF treated with an HFNC in an ED between October 2020 and April 2022. The ROX index was calculated at 1, 2, 4, 6, 12, and 24 h after HFNC placement. The primary outcome was the failure of the HFNC, which was defined as the need for subsequent intubation or death within 72 h. A receiver operating characteristic (ROC) curve was used to evaluate discriminative power of the ROX index for HFNC failure. RESULTS: Among 448 patients with AHRF treated with an HFNC in an ED, 78 (17.4%) patients were confirmed to have COVID-19. There was no significant difference in the HFNC failure rates between the non-COVID-19 and COVID-19 groups (29.5% vs. 33.3%, p = 0.498). The median ROX index was higher in the non-COVID-19 group than in the COVID-19 group at all time points. The prognostic power of the ROX index for HFNC failure as evaluated by the area under the ROC curve was generally higher in the COVID-19 group (0.73-0.83) than the non-COVID-19 group (0.62-0.75). The timing of the highest prognostic value of the ROX index for HFNC failure was at 4 h for the non-COVID-19 group, whereas in the COVID-19 group, its performance remained consistent from 1 h to 6 h. The optimal cutoff values were 6.48 and 5.79 for the non-COVID-19 and COVID-19 groups, respectively. CONCLUSIONS: The ROX index had an acceptable discriminative power for predicting HFNC failure in patients with AHRF with and without COVID-19 in the ED. However, the higher ROX index thresholds than those in previous publications involving intensive care unit (ICU) patients suggest the need for careful monitoring and establishment of a new threshold for patients admitted outside the ICU.

NEWS2, S/F-ratio and ROX-index at emergency department for the prediction of adverse outcomes in COVID-19 patients: An external validation study.

BACKGROUND: In the context of the COVID-19 pandemic, the early and accurate identification of patients at risk of deterioration was crucial in overcrowded and resource-limited emergency departments. This study conducts an external validation for the evaluation of the performance of the National Early Warning Score 2 (NEWS2), the S/F ratio, and the ROX index at ED admission in a large cohort of COVID-19 patients from Colombia, South America, assessing the net clinical benefit with decision curve analysis. METHODS: A prospective cohort study was conducted on 6907 adult patients with confirmed COVID-19 admitted to a tertiary care ED in Colombia. The study evaluated the diagnostic performance of NEWS2, S/F ratio, and ROX index scores at ED admission using the area under the receiver operating characteristic curve (AUROC) for discrimination, calibration, and decision curve analysis for the prediction of intensive care unit admission, invasive mechanical ventilation, and in-hospital mortality. RESULTS: We included 6907 patients who presented to the ED with confirmed SARS-CoV-2 infection from March 2020 to November 2021. Mean age was 51 (35-65) years and 50.4% of patients were males. The rate of intensive care unit admission was 28%, and in-hospital death was 9.8%. All three scores have good discriminatory performance for the three outcomes based on the AUROC. S/F ratio showed miscalibration at low predicted probabilities and decision curve analysis indicated that the NEWS2 score provided a greater net benefit compared to other scores across at a 10% threshold to decide ED admission at a high-level of care facility. CONCLUSIONS: The NEWS2, S/F ratio, and ROX index at ED admission have good discriminatory performances in COVID-19 patients for the prediction of adverse outcomes, but the NEWS2 score has a higher net benefit underscoring its clinical utility in optimizing patient management and resource allocation in emergency settings.

Respiratory Rate Oxygenation (ROX) index as predictor of high flow nasal cannula in pediatric patients in pediatric intensive care unit.

BACKGROUND: High-flow nasal cannula (HFNC) is often used in pediatric populations with respiratory distress. In adults, the respiratory-rate oxygenation (ROX) index is used as a predictor of HFNC therapy; however, children have age-associated differences in respiratory rate, thus may not be applicable to children. This study aims to find the reliability of ROX index and modified P-ROX index as predictors of HFNC therapy failure in pediatric patients. METHODS: Subjects in this analytical cross-sectional study were taken from January 2023 until November 2023 in Cipto Mangunkusumo Hospital. Inclusion criteria are children aged 1 month to 18 years with respiratory distress and got HFNC therapy. Receiver operating characteristics (ROC) analysis was used to find mP-ROX index cutoff value as a predictor of HFNC failure. The area under curve (AUC) score of mP-ROX index was assessed at different time point. RESULTS: A total of 102 patients, with 70% of the population with pneumonia, were included in this study. There are significant differences in the ROX index between the successful and failed HFNC group therapy (p < 0.05). This study suggests that mP-ROX index is not useful as predictor of HFNC therapy in pediatrics. While ROX index < 5.52 at 60 min and < 5.68 at 90 min after HFNC initiation have a sensitivity of 90% and specificity of 71%, sensitivity of 78% and specificity of 76%, respectively. CONCLUSION: mP-ROX index is not useful as a predictor of HFNC therapy in pediatrics. Meanwhile, ROX index at 60 min and 90 min after initiation of HFNC is useful as a predictor of HFNC failure.

The ROX, shock and diastolic shock indexes in the prediction of mortality in COVID-19.

OBJECTIVES: The aim of this study is to determine the role of Respiratory Rate Oxygenation (ROX), shock, and diastolic shock indexes ​​in predicting mortality in coronavirus disease 2019 (COVID-19) patients admitted to the emergency department. BACKGROUND: The COVID-19 spread worldwide in a short time and caused a major pandemic. The ROX, shock, and diastolic shock indexes are used in various life-threatening clinical situations. The use of these indexes in triage at emergency departments can accelerate the determination of COVID-19 patients' severity. METHODS: The ROX, shock and diastolic shock indices were calculated and recorded. Patients were divided into three groups; 1) who were discharged from the hospital, 2) who were admitted to the hospital and 3) who were admitted to the intensive care unit. RESULTS: Increased diastolic shock index and decreased ROX index were found to be independent risk factors for mortality. In the prediction of mortality, the sensitivity and specificity of the diastolic shock index were 61.2% and 60.8%, respectively. However, the sensitivity and specificity of ROX index was 73.1% and 71.5%, respectively. CONCLUSION: In conclusion, we found that the ROX index had higher sensitivity and specificity than other indexes in predicting mortality in the evaluation of COVID-19 patients (Tab. 3, Fig. 2, Ref. 18).

Performance of the ROX index in predicting high flow nasal cannula failure in COVID-19 patients: a systematic review and meta-analysis.

COVID-19 patients with acute hypoxemic respiratory failure (AHRF) benefit from high flow nasal cannula (HFNC) oxygen therapy. However, delays in initiating invasive ventilation after HFNC failure are associated with poorer outcomes. The respiratory oxygenation (ROX) index, combining SpO2/FiO2 and respiratory rate, can predict HFNC failure. This meta-analysis evaluated the optimal ROX index cut-offs in predicting HFNC failure among COVID-19 patients at different measurement timings and clinical settings. Three databases were searched for eligible papers. From each study, we reconstructed the confusion matrices at different cut-offs, fitted linear mixed models to estimate the ROX index distribution function, and derived the area under the summary receiver operator characteristic curve (sAUC) and optimal cut-offs to predict HFNC failure. 24 studies containing 4790 patients were included. Overall sAUC was 0.771 (95% CI: 0.666-0.847) (optimal cut-off: 5.23, sensitivity: 0.732, specificity: 0.690). The cut-off values to achieve 80%, 90% sensitivity, 80%, 90% specificity were 5.70, 6.69, 4.45, 3.37, respectively. We stratified the analysis by ROX measurement time and estimated optimal cut-offs and cut-offs to achieve 80% sensitivity and specificity. For 2-6 h and 6-12 h post-HFNC initiation, we propose the use of 80% specific cut-offs to rule in HFNC failure of < 5.33 and < 3.69, respectively. For 12-24 h post-HFNC initiation, we propose the use of the 80% sensitive cut-off of > 6.07 to rule out HFNC failure. Our analysis confirms the overall utility of the ROX index in risk stratification of COVID-19 patients with AHRF receiving HFNC and provides potentially useful cut-offs for different times from HFNC initiation.

Daily ROX index can predict transitioning to mechanical ventilation within the next 24 h in COVID-19 patients on HFNC.

INTRODUCTION: High flow nasal cannula (HFNC) is used to prevent invasive ventilation in COVID-19-associated hypoxemia. The respiratory rate­oxygenation (ROX) index has been reported to predict failure of HFNC in patients with COVID-19 pneumonia during the intensive care unit stay when measured in first hours of therapy. However, the clinical course of ICU patients may change substantially in the first days of admission. The objective of this study was to investigate whether ROX index obtained in the first four days of ICU admission could predict the need for invasive respiratory support within the next 24 h of measurements. METHODS: A retrospective cross-sectional study was performed using a database that included adult patients with COVID-19 pneumonia treated in the ICU. Patients were followed from ICU admission and ROX index was calculated daily on HFNC. Receiver operating characteristics curves (ROCs) were performed. RESULTS: Two hundred forty-nine patients were enrolled, 48% of whom require mechanical ventilation (MV). The area under the ROC of the pooled 4-day values of the ROX index as a predictor of transition from HFNC to MV within 24 h of measurements was 0.86 (95%CI 0.83 to 0.88, P < 0.001) with a cutoff point of 4.06. CONCLUSION: In COVID-19 patients in high flow nasal cannula, daily ROX index measurements successfully predicted transition to mechanical ventilation within the next 24 h.

Reliability of the respiratory rate and oxygenation index for successful high-flow nasal cannula support in coronavirus disease pneumonia: a retrospective cohort study.

BACKGROUND: High-flow nasal cannula (HFNC) therapy is an important non-invasive respiratory support in acute respiratory failure, including coronavirus disease (COVID-19) pneumonia. Although the respiratory rate and oxygenation (ROX) index is a simple and useful predictor for HFNC failure and mortality, there is limited evidence for its use in patients with COVID-19 pneumonia. We aimed to evaluate the ROX index as a predictor for HFNC failure in patients with COVID-19 pneumonia. We also evaluated the ROX index as a predictor for 28-day mortality. METHODS: In this single-center, retrospective, cohort study, 248 patients older than 18 years of age with COVID-19 pneumonia received HFNC therapy for acute respiratory failure. The ROX index was evaluated within 4 h from the start of HFNC therapy. Past medical history, laboratory data, and the ROX index were evaluated as predictors for HFNC failure and 28-day mortality. RESULTS: The ROX index < 4.88 showed a significantly high risk ratio for HFNC failure (2.13 [95% confidence interval [CI]: 1.47 - 3.08], p < 0.001). The ROX index < 4.88 was significantly associated with 28-day mortality (p = 0.049) in patients with COVID-19 pneumonia receiving HFNC therapy. Age, chronic hypertension, high lactate dehydrogenase level, and low ROX index showed significantly high risk ratio for HFNC failure. C-reactive protein level and low ROX index were predictors of 28-day morality. CONCLUSION: The ROX index is a useful predictor for HFNC success and 28-day mortality in patients with COVID-19 pneumonia receiving HFNC therapy. TRIAL REGISTRATION: An independent ethics committee approved the study (Research Ethics Review Committee of Kobe City Medical Center General Hospital [number: zn220303; date: February 21, 2022]), which was performed in accordance with the Declaration of Helsinki, Guidelines for Good Clinical Practice.

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.

Using Vital Signs to Place Acutely Ill Patients Quickly and Easily into Clinically Helpful Pathophysiologic Categories: Derivation and Validation of Eight Pathophysiologic Categories in Two Distinct Patient Populations of Acutely Ill Patients.

BACKGROUND: Early warning scores reliably identify patients at risk of imminent death, but do not provide insight into what may be wrong with the patient or what to do about it. OBJECTIVE: Our aim was to explore whether the Shock Index (SI), pulse pressure (PP), and ROX Index can place acutely ill medical patients in pathophysiologic categories that could indicate the interventions required. METHODS: A retrospective post-hoc analysis of previously obtained and reported clinical data for 45,784 acutely ill medical patients admitted to a major regional referral Canadian hospital between 2005 and 2010 and validated on 107,546 emergency admissions to four Dutch hospitals between 2017 and 2022. RESULTS: SI, PP, and ROX values divided patients into eight mutually exclusive physiologic categories. Mortality was highest in patient categories that included ROX Index value < 22, and a ROX Index value < 22 multiplied the risk of any other abnormality. Patients with a ROX Index value < 22, PP < 42 mm Hg, and SI > 0.7 had the highest mortality and accounted for 40% of deaths within 24 h of admission, whereas patients with a PP ≥ 42 mm Hg, SI ≤ 0.7, and ROX Index value ≥ 22 had the lowest risk of death. These results were the same in both the Canadian and Dutch patient cohorts. CONCLUSIONS: SI, PP, and ROX Index values can place acutely ill medical patients into eight mutually exclusive pathophysiologic categories with different mortality rates. Future studies will assess the interventions needed by these categories and their value in guiding treatment and disposition decisions.

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.

A new index, Respiratory Insufficiency index and Modified Early Warning Scores predict extubation failure.

Background: Extubation failure occurs in 5%-20% of patients and is associated with poor clinical outcomes. The primary aim of this project was to determine the predictive ability of the Respiratory Insufficiency (RI) index, Respiratory Oxygenation (ROX) index and Modified Early Warning Score (MEWS) in identifying extubation failure. Methods: This was a secondary analysis of a prior cross-sectional retrospective study conducted from February 2018 through December 2018 among adult subjects who received mechanical ventilation for more than 24 h. Extubation failure was defined as the need for reintubation or rescue non-invasive ventilation (NIV) within 48 h after planned extubation. Univariate analysis and logistic regression were used to identify the predictors and final model was validated using 10-fold cross validation. Nomogram was constructed based on the final model. Results: Of 216 enrolled subjects, 46 (21.3%) experienced extubation failure. The median RI index 1-h post extubation was 20 [interquartile range [IQR] 16.33-24.24] for success group and 27.02 [IQR 22.42-33.83] for the failure group (P<0.001). The median ROX index 1-h post extubation was 16.66 [IQR 12.57-19.84] for success group and 11.11 [IQR 8.09-14.67] for failure group (P<0.001). The median MEWS 1-h post extubation was 2 [IQR 1-3] for the success group and 4 [IQR 3-5] for the failure group (P<0.001). In multivariable analysis, age >60 years [OR 3.89 (95% CI 1.56-9.73); P=0.004], MEWS >4 [OR 4.01 (95% CI (1.59-10.14); P=0.003] and, RI index >20 [OR 4.50 (95% CI 1.43-14.21); P=0.010] were independently associated with extubation failure. Conclusion: In the present study, RI index and MEWS were independently associated with predicting extubation failure within 1 h of extubation. A prospective validation study is warranted to establish the role of these indices in predicting extubation outcome.

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.

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.

The ROX index as a predictor of high-flow nasal cannula outcome in pneumonia patients with acute hypoxemic respiratory failure: a systematic review and meta-analysis.

BACKGROUND: The respiratory rate-oxygenation (ROX) index has been increasingly applied to predict the outcome of high-flow nasal cannula (HFNC) in pneumonia patients with acute hypoxemic respiratory failure (AHRF). However, its diagnostic accuracy for the HFNC outcome has not yet been systematically assessed. This meta-analysis sought to evaluate the predictive performance of the ROC index for the successful weaning from HFNC in pneumonia patients with AHRF. METHODS: A literature search was conducted on electronic databases through February 12, 2022, to retrieve studies that investigated the diagnostic accuracy of the ROC index for the outcome of HFNC application in pneumonia patients with AHRF. The area under the hierarchical summary receiver operating characteristic curve (AUHSROC) was estimated as the primary measure of diagnostic accuracy due to the varied cutoff values of the index. We observed the distribution of the cutoff values and estimated the optimal threshold with corresponding 95% confidential interval (CI). RESULTS: Thirteen observational studies comprising 1751 patients were included, of whom 1003 (57.3%) successfully weaned from HFNC. The ROC index exhibits good performance for predicting the successful weaning from HFNC in pneumonia patients with AHRF, with an AUHSROC of 0.81 (95% CI 0.77-0.84), a pooled sensitivity of 0.71 (95% CI 0.64-0.78), and a pooled specificity of 0.78 (95% CI 0.70-0.84). The cutoff values of the ROX index were nearly conically symmetrically distributed; most data were centered between 4.5 and 6.0, and the mean and median values were 4.8 (95% CI 4.2-5.4) and 5.3 (95% CI 4.2-5.5), respectively. Moreover, the AUHSROC in the subgroup of measurement within 6 h after commencing HFNC was comparable to that in the subgroup of measurement during 6-12 h. The stratified analyses also suggested that the ROC index was a reliable predictor of HFNC success in pneumonia patients with coronavirus disease 2019. CONCLUSIONS: In pneumonia patients with AHRF, the ROX index measured within 12 h after HFNC initiation is a good predictor of successful weaning from HFNC. The range of 4.2-5.4 may represent the optimal confidence interval for the prediction of HFNC outcome.

Breathing pattern, accessory respiratory muscles work, and gas exchange evaluation for prediction of NIV failure in moderate-to-severe COVID-19-associated ARDS after deterioration of respiratory failure outside ICU: the COVID-NIV observational study.

BACKGROUND: Data on the efficacy of non-invasive ventilation (NIV) after progression of respiratory failure in patients who have already received oxygen therapy, or CPAP outside ICU is limited. The study aimed to find predictors of NIV failure based on breathing pattern, gas exchange, and accessory respiratory muscles evaluation in patients who progressed to moderate-to-severe COVID-19 ARDS. METHODS: This was a prospective observational study in patients with moderate-to-severe COVID-19-ARDS on NIV (n = 80) admitted to COVID-ICU of Sechenov University. The combined success rate for conventional oxygen and CPAP outside ICU was 78.6% (440 of 560 patients). The primary endpoints were intubation rate and mortality. We measured respiratory rate, exhaled tidal volume (Vte), mean peak inspiratory flow (PIF), inspiratory time (Ti), PaO2, SpO2, end-tidal carbon dioxide (PETCO2), and Patrick score, and calculated ROX index, PaO2/FiO2, ventilatory ratio, and alveolar dead space (Vdalv/Vt) on Days 1, 3, 5, 7, 10, and 14. For all significant differences between NIV success and failure groups in measured data, we performed ROC analysis. RESULTS: NIV failure rate in ICU after deterioration of respiratory failure outside ICU was 71.3% (n = 57). Patients with the subsequent NIV failure were older at inclusion, more frail, had longer duration of disease before ICU admission, and higher rate of CPAP use outside ICU. ROC-analysis revealed that the following respiratory parameters after 48 h of NIV can serve as a predictors for NIV failure in moderate-to-severe COVID-19-associated ARDS: PaO2/FiO2 < 112 mmHg (AUROC 0.90 (0.93-0.97), p < 0.0001); PETCO2 < 19.5 mmHg (AUROC 0.84 (0.73-0.94), p < 0.0001); VDalv/VT > 0.43 (AUROC 0.78 (0.68-0.90), p < 0.0001); ROX-index < 5.02 (AUROC 0.89 (0.81-0.97), p < 0.0001); Patrick score > 2 points (AUROC 0.87 (0.78-0.96), p = 0.006). CONCLUSION: In patients who progressed to moderate-to-severe COVID-19-ARDS probability of NIV success rate was about 1/3. Prediction of the NIV failure can be made after 48 h based on ROX index < 5.02, PaO2/FiO2 < 112 mmHg, PETCO2 < 19.5 mmHg, and Patrick score > = 2. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT04667923 , registered on 16/12/2020.

S/F and ROX indices in predicting failure of high-flow nasal cannula in children.

BACKGROUND: A high-flow nasal cannula (HFNC) is a useful respiratory support for children with respiratory distress; however, it elevates the risk of belated intubation. Recently, indices based on percutaneous oxygen saturation, a fraction of inspired oxygen, and respiratory rate (RR) have been suggested for the prediction of HFNC failure. We aimed to evaluate various indices predicting HFNC failure in children who started receiving HFNC at a tertiary center for 27 months. METHODS: Cases of HFNC failure were classified as hypoxic respiratory failure (HRF) or non-HRF (NHRF) depending on the cause of intubation. The ratio of percutaneous oxygen saturation to the fraction of inspired oxygen (S/F), the ratio of S/F to RR (ROX), the ratio of S/F to RR/median RR (ROX-M), and the ratio of S/F to z-score of RR (ROX-Z) were calculated and compared between groups. RESULTS: Of the 152 cases, 45 (29.6%) failed to wean from the HFNC support, of which 21 (46.7%) were HRFs and 24 (53.3%) were NHRFs. The S/F and ROX-M at 6 h and 3 h, respectively, predicted HRF well with a high area under the curve. Initial hypercapnia and low weight were good predictors for NHRF. CONCLUSIONS: For the management of children with HFNC, these risk factors and indicators should be monitored to make an early decision regarding intubation.

Knowledge translation tools to guide care of non-intubated patients with acute respiratory illness during the COVID-19 Pandemic.

Providing optimal care to patients with acute respiratory illness while preventing hospital transmission of COVID-19 is of paramount importance during the pandemic; the challenge lies in achieving both goals simultaneously. Controversy exists regarding the role of early intubation versus use of non-invasive respiratory support measures to avoid intubation. This review summarizes available evidence and provides a clinical decision algorithm with risk mitigation techniques to guide clinicians in care of the hypoxemic, non-intubated, patient during the COVID-19 pandemic. Although aerosolization of droplets may occur with aerosol-generating medical procedures (AGMP), including high flow nasal oxygen and non-invasive ventilation, the risk of using these AGMP is outweighed by the benefit in carefully selected patients, particularly if care is taken to mitigate risk of viral transmission. Non-invasive support measures should not be denied for conditions where previously proven effective and may be used even while there is suspicion of COVID-19 infection. Patients with de novo acute respiratory illness with suspected/confirmed COVID-19 may also benefit. These techniques may improve oxygenation sufficiently to allow some patients to avoid intubation; however, patients must be carefully monitored for signs of increased work of breathing. Patients showing signs of clinical deterioration or high work of breathing not alleviated by non-invasive support should proceed promptly to intubation and invasive lung protective ventilation strategy. With adherence to these principles, risk of viral spread can be minimized.

Admission SpO2 and ROX index predict outcome in patients with COVID-19.

BACKGROUND: This study aimed to evaluate the accuracy of pulse oximetry-derived oxygen saturation (SpO2) on room air, determined at hospital admission, as a predictor for the need for mechanical ventilatory support in patients with Coronavirus Disease-2019 (COVID-19). METHODS: In this retrospective observational study, demographic and clinical details of the patients were obtained during ICU admission. SpO2 and respiratory rate (RR) on room air were determined within the first 6 h of hospital admission. As all measurements were obtained on room air, we calculated the simplified respiratory rate­oxygenation (ROX) index by dividing the SpO2 by the RR. Based on the use of any assistance of mechanical ventilator (invasive or noninvasive), patients were divided into mechanical ventilation (MV) group and oxygen therapy group. The accuracy of the SpO2, CT score, and ROX index to predict the need to MV were determined using the Area under receiver operating curve (AUC). RESULTS: We included 72 critically ill patients who tested COVID-19-positive. SpO2 on the room air could predict any MV requirement (AUC [95% confidence interval]: 0.9 [0.8-0.96], sensitivity: 70%, specificity 100%, cut-off value ≤78%, P < 0.001). Within the MV group, the use of noninvasive ventilation (NIV) was successful in 37 (74%) patients, whereas 13 patients (26%) required endotracheal intubation. The cut-off ROX value for predicting early NIV failure was ≤1.4, with a sensitivity of 85%, a specificity of 86%, and an AUC of 0.86 (95% confidence interval of 0.73-0.94, P < 0.0001). CONCLUSIONS: A baseline SpO2 ≤78% is an excellent predictor of MV requirement with a positive predictive value of 100%. Moreover, the ROX index measured within the first 6 h of hospital admission is a good indicator of early NIV failure.