Failure of high-flow nasal cannula therapy may delay intubation and increase mortality

ChatGPT achieves comparable accuracy to specialist physicians in predicting the efficacy of high-flow oxygen therapy

Background

The failure of high-flow nasal cannula (HFNC) oxygen therapy can necessitate endotracheal intubation in patients, making timely prediction of the intubation risk following HFNC therapy crucial for reducing mortality due to delays in intubation.

Objectives

To investigate the accuracy of ChatGPT in predicting the endotracheal intubation risk within 48 h following HFNC therapy and compare it with the predictive accuracy of specialist and non-specialist physicians.

Methods

We conducted a prospective multicenter cohort study based on the data of 71 adult patients who received HFNC therapy. For each patient, their baseline data and physiological parameters after 6-h HFNC therapy were recorded to create a 6-alternative-forced-choice questionnaire that asked participants to predict the 48-h endotracheal intubation risk using scale options ranging from 1 to 6, with higher scores indicating a greater risk. GPT-3.5, GPT-4.0, respiratory and critical care specialist physicians and non-specialist physicians completed the same questionnaires (N = 71) respectively. We then determined the optimal diagnostic cutoff point, using the Youden index, for each predictor and 6-h ROX index, and compared their predictive performance using receiver operating characteristic (ROC) analysis.

Results

The optimal diagnostic cutoff points were determined to be ≥ 4 for both GPT-4.0 and specialist physicians. GPT-4.0 demonstrated a precision of 76.1 %, with a specificity of 78.6 % (95%CI = 52.4-92.4 %) and sensitivity of 75.4 % (95%CI = 62.9-84.8 %). In comparison, the precision of specialist physicians was 80.3 %, with a specificity of 71.4 % (95%CI = 45.4-88.3 %) and sensitivity of 82.5 % (95%CI = 70.6-90.2 %). For GPT-3.5 and non-specialist physicians, the optimal diagnostic cutoff points were ≥5, with precisions of 73.2 % and 64.8 %, respectively. The area under the curve (AUC) in ROC analysis for GPT-4.0 was 0.821 (95%CI = 0.698-0.943), which was the highest among the predictors and significantly higher than that of non-specialist physicians [0.662 (95%CI = 0.518-0.805), P = 0.011].

Conclusion

GPT-4.0 achieves an accuracy level comparable to specialist physicians in predicting the 48-h endotracheal intubation risk following HFNC therapy, based on patient baseline data and physiological parameters after 6-h HFNC therapy.

High-flow nasal cannula oxygen therapy is equally effective to noninvasive ventilation for mild-moderate acute respiratory distress syndrome in patients with acute pancreatitis: A single-center, retrospective cohort study

BACKGROUND

The use of high-flow nasal cannula (HFNC) oxygen therapy is gaining popularity for the treatment of acute hypoxic respiratory failure. However, limited evidence exists regarding the effectiveness of HFNC for acute respiratory distress syndrome (ARDS) in patients with acute pancreatitis (AP).

METHODS

This retrospective analysis focused on AP patients with mild-moderate ARDS, who were treated with either HFNC or noninvasive ventilation (NIV) in the emergency medicine department, from January 2020 to December 2022. The primary endpoint was treatment failure, defined as either invasive ventilation or a switch to any other study treatment (NIV for patients in the NFNC group and vice versa).

RESULTS

A total of 146 patients with AP (68 in the HFNC group and 78 in the NIV group) were included in this study. The treatment failure rate in the HFNC group was 17.6% and 19.2% in the NIV group - a risk difference of -1.6% (95% CI, -11.3 to 14.0%; P = 0.806). The most common causes of failure in the HFNC group were aggravation of respiratory distress and hypoxemia. However, in the NIV group, the most common reasons for failure were treatment intolerance and exacerbation of respiratory distress. Treatment intolerance in the HFNC group was significantly lower than that in the NIV group (16.7% vs 60.0%, 95% CI -66.8 to -6.2; P = 0.023). Multivariate logistic regression analysis showed that body mass index (≥28), acute physiology and chronic health evaluation II score (≥15), partial arterial oxygen tension/fraction of inspired oxygen (≤200), and respiratory rate (≥32/min) at 1 hour were independent predictors of HFNC failure.

CONCLUSION

In AP patients with mild-moderate ARDS, the usage of HFNC did not lead to a higher rate of treatment failure when compared to NIV. HFNC is an ideal choice of respiratory support for patients with NIV intolerance, but clinical application should pay attention to the influencing factors of its treatment failure.

Effectiveness of early high-flow nasal oxygen therapy after extubation of patients in the intensive care unit

PURPOSE

This study aimed to evaluate the impact of early high-flow nasal oxygen (HFNO) therapy initiation using a pre-determined respiratory rate‑oxygenation (ROX) index on reducing reintubation rates and duration of intensive care unit (ICU) stay in post-extubated patients.

MATERIALS AND METHODS

We enrolled a total of 145 extubated patients (mean age: 67.1 ± 12.9 years; sex: 96 male and 49 female; acute physiology and chronic health evaluation II score: 18.4 ± 6.8 points) classified into two groups: 71 patients admitted to the ICU before establishing extubation criteria and 74 patients after criteria implementation, over a 6-month period. We compared the HFNO reintubation rates and ROX index at 2 h post-extubation before and after implementing early HFNO criteria.

RESULTS

The utilization rate of HFNO pre- and post-establishment of early HFNO criteria did not differ significantly (19.7% vs. 17.6%). However, the reintubation rate significantly decreased (11.3% vs. 4.1%, P < 0.05) with early HFNO use. Additionally, significant differences were observed in the total intubation period (5.2 ± 7.0 vs. 2.5 ± 2.7 days, P < 0.05) and ICU duration (8.6 ± 9.7 vs. 5.8 ± 5.6 days, P < 0.05).

CONCLUSIONS

Early initiation of HFNO guided by the ROX index threshold post-extubation in patients admitted to ICU is associated with reduced reintubation rates and shorter ICU stays.

When to intubate in acute hypoxaemic respiratory failure? Options and opportunities for evidence-informed decision making in the intensive care unit

The optimal timing of intubation in acute hypoxaemic respiratory failure is uncertain and became a point of controversy during the COVID-19 pandemic. Invasive mechanical ventilation is a potentially life-saving intervention but carries substantial risks, including injury to the lungs and diaphragm, pneumonia, intensive care unit-acquired muscle weakness, and haemodynamic impairment. In deciding when to intubate, clinicians must balance premature exposure to the risks of ventilation with the potential harms of unassisted breathing, including disease progression and worsening multiorgan failure. Currently, the optimal timing of intubation is unclear. In this Personal View, we examine a range of parameters that could serve as triggers to initiate invasive mechanical ventilation. The utility of a parameter (eg, the ratio of arterial oxygen tension to fraction of inspired oxygen) to predict the likelihood of a patient undergoing intubation does not necessarily mean that basing the timing of intubation on that parameter will improve therapeutic outcomes. We examine options for clinical investigation to make progress on establishing the optimal timing of intubation.

Development of clinical tools to estimate the breathing effort during high-flow oxygen therapy: A multicenter cohort study

INTRODUCTION AND OBJECTIVES

Quantifying breathing effort in non-intubated patients is important but difficult. We aimed to develop two models to estimate it in patients treated with high-flow oxygen therapy.

PATIENTS AND METHODS

We analyzed the data of 260 patients from previous studies who received high-flow oxygen therapy. Their breathing effort was measured as the maximal deflection of esophageal pressure (ΔPes). We developed a multivariable linear regression model to estimate ΔPes (in cmH2O) and a multivariable logistic regression model to predict the risk of ΔPes being >10 cmH2O. Candidate predictors included age, sex, diagnosis of the coronavirus disease 2019 (COVID-19), respiratory rate, heart rate, mean arterial pressure, the results of arterial blood gas analysis, including base excess concentration (BEa) and the ratio of arterial tension to the inspiratory fraction of oxygen (PaO2:FiO2), and the product term between COVID-19 and PaO2:FiO2.

RESULTS

We found that ΔPes can be estimated from the presence or absence of COVID-19, BEa, respiratory rate, PaO2:FiO2, and the product term between COVID-19 and PaO2:FiO2. The adjusted R2 was 0.39. The risk of ΔPes being >10 cmH2O can be predicted from BEa, respiratory rate, and PaO2:FiO2. The area under the receiver operating characteristic curve was 0.79 (0.73-0.85). We called these two models BREF, where BREF stands for BReathing EFfort and the three common predictors: BEa (B), respiratory rate (RE), and PaO2:FiO2 (F).

CONCLUSIONS

We developed two models to estimate the breathing effort of patients on high-flow oxygen therapy. Our initial findings are promising and suggest that these models merit further evaluation.

The utility of the respiratory rate-oxygenation index as a predictor of treatment response in dogs receiving high-flow nasal cannula oxygen therapy

Objective

This study aims to evaluate the respiratory rate-oxygenation index (ROX) and the ratio of pulse oximetry saturation (SpO2) to the fraction of inspired oxygen (FiO2) (SpO2/FiO2, [SF]) to determine whether these indices are predictive of outcome in dogs receiving high-flow nasal cannula oxygen therapy (HFNOT).

Design

This is a prospective observational study.

Setting

This study was carried out at two university teaching hospitals.

Animals

In total, 88 dogs treated with HFNOT for hypoxemic respiratory failure due to various pulmonary diseases were selected.

Measurements and main results

The ROX index was defined as the SF divided by the respiratory rate (RR). ROX and SF were calculated at baseline and for each hour of HFNOT. The overall success rate of HFNOT was 38% (N = 33/88). Variables predicting HFNOT success were determined using logistic regression, and the predictive power of each variable was assessed using the area under the receiver operating curve (AUC). ROX and SF were adequately predictive of HFNOT success when averaged over 0-16 h of treatment, with similar AUCs of 0.72 (95% confidence interval [CI] 0.60-0.83) and 0.77 (95% CI 0.66-0.87), respectively (p < 0.05). SF showed acceptable discriminatory power in predicting HFNOT outcome at 7 h, with an AUC of 0.77 (95% CI 0.61-0.93, p = 0.013), and the optimal cutoff for predicting HFNC failure at 7 h was SF ≤ 191 (sensitivity 83% and specificity 76%).

Conclusion

These indices were easily obtained in dogs undergoing HFNOT. The results suggest that ROX and SF may have clinical utility in predicting the outcomes of dogs on HFNOT. Future studies are warranted to confirm these findings in a larger number of dogs in specific disease populations.

Factors associated with intubation in patients with acute hypoxaemic respiratory failure treated with high-flow nasal cannula oxygen therapy: A prospective, observational study

BACKGROUND

High-flow nasal cannula (HFNC) oxygen is an alternative to conventional oxygen in acute hypoxaemic respiratory failure. Some patients require intubation, with a risk of delay; thus, early predictors may identify those requiring earlier intubation. The "ROX" index (ratio of pulse oximetry/fraction of inspired oxygen to respiratory rate) predicts intubation in patients with pneumonia treated with HFNC therapy, but this index has not been validated in non-pneumonia causes of acute hypoxaemic respiratory failure.

AIM/OBJECTIVE

The aim of this study was to identify factors associated with intubation in a heterogeneous group of patients with acute hypoxaemic respiratory failure treated with HFNC oxygen.

METHODS

This prospective observational study was undertaken in an Australian tertiary intensive care unit and included patients over 18 y of age with acute hypoxaemic respiratory failure who were treated with oxygen via HFNC. Vital signs and arterial blood gases were recorded prospectively at baseline and regular prespecified intervals for 48 h after HFNC initiation. Multivariate logistic regression was used to identify the factors associated with intubation.

RESULTS

Forty-three patients were included (N = 43). The multivariate factors associated with intubation were admission Sequential Organ Failure Assessment score (odds ratio [OR]: 1.94 [95% confidence interval {CI}: 1.06-3.57]; p = 0.032) and Pneumonia Severity Index (OR: 0.95 [95% CI: 0.90-0.99]; p = 0.034). The ROX index was not independently associated with intubation when adjusted for Sequential Organ Failure Assessment score (OR: 0.71 [95% CI: 0.47-1.06]; p = 0.09). There was no difference in mortality between patients intubated early (<24 h) compared to those intubated late.

CONCLUSIONS

Intubation was associated with admission Sequential Organ Failure Assessment score and Pneumonia Severity Index. The ROX index was not associated with intubation when adjusted for admission Sequential Organ Failure Assessment score. Outcomes were similar irrespective of whether patients were intubated late rather than early.

Duration of the first prone positioning maneuver and its association with 90-day mortality in patients with acute respiratory failure due to COVID-19: A retrospective study of time terciles

OBJECTIVE

To investigate the association between the duration of the first prone positioning maneuver (PPM) and 90-day mortality in patients with C-ARDS.

DESIGN

Retrospective, observational, and analytical study.

SETTING

COVID-19 ICU of a tertiary hospital.

PATIENTS

Adults over 18 years old, with a confirmed diagnosis of SARS-CoV-2 disease requiring PPM.

INTERVENTIONS

Multivariable analysis of 90-day survival.

MAIN VARIABLES OF INTEREST

Duration of the first PPM, number of PPM sessions, 90-day mortality.

RESULTS

271 patients undergoing PPM were analyzed: first tertile (n = 111), second tertile (n = 95) and third tertile (n = 65). The results indicated that the median duration of PDP was 14 h (95% CI: 10-16 h) in the first tertile, 19 h (95% CI: 18-20 h) in the second tertile and 22 h (95% CI: 21-24 h) in the third tertile. Comparison of survival curves using the Logrank test did not reach statistical significance (p = 0.11). Cox Regression analysis showed an association between the number of pronation sessions (patients receiving between 2 and 5 sessions (HR = 2.19; 95% CI: 1.07-4.49); and those receiving more than 5 sessions (HR = 6.05; 95% CI: 2.78-13.16) and 90-day mortality.

CONCLUSIONS

while the duration of PDP does not appear to significantly influence 90-day mortality, the number of pronation sessions is identified as a significant factor associated with an increased risk of mortality.

Diagnosis and Management of Acute Respiratory Failure

Acute hypoxemic respiratory failure is defined by Pao2 less than 60 mm Hg or SaO2 less than 88% and may result from V/Q mismatch, shunt, hypoventilation, diffusion limitation, or low inspired oxygen tension. Acute hypercapnic respiratory failure is defined by Paco2 ≥ 45 mm Hg and pH less than 7.35 and may result from alveolar hypoventilation, increased fraction of dead space, or increased production of carbon dioxide. Early diagnostic maneuvers, such as measurement of SpO2 and arterial blood gas, can differentiate the type of respiratory failure and guide next steps in evaluation and management.

Switches in non-invasive respiratory support strategies during acute hypoxemic respiratory failure: Need to monitoring from a retrospective observational study

OBJECTIVE

To explore combined non-invasive-respiratory-support (NIRS) patterns, reasons for NIRS switching, and their potential impact on clinical outcomes in acute-hypoxemic-respiratory-failure (AHRF) patients.

DESIGN

Retrospective, single-center observational study.

SETTING

Intensive Care Medicine.

PATIENTS

AHRF patients (cardiac origin and respiratory acidosis excluded) underwent combined NIRS therapies such as non-invasive-ventilation (NIV) and High-Flow-Nasal-Cannula (HFNC).

INTERVENTIONS

Patients were classified based on the first NIRS switch performed (HFNC-to-NIV or NIV-to-HFNC), and further specific NIRS switching strategies (NIV trial-like vs. Non-NIV trial-like and single vs. multiples switches) were independently evaluated.

MAIN VARIABLES OF INTEREST

Reasons for switching, NIRS failure and mortality rates.

RESULTS

A total of 63 patients with AHRF were included, receiving combined NIRS, 58.7% classified in the HFNC-to-NIV group and 41.3% in the NIV-to-HFNC group. Reason for switching from HFNC to NIV was AHRF worsening (100%), while from NIV to HFNC was respiratory improvement (76.9%). NIRS failure rates were higher in the HFNC-to-NIV than in NIV-to-HFNC group (81% vs. 35%, p < 0.001). Among HFNC-to-NIV patients, there was no difference in the failure rate between the NIV trial-like and non-NIV trial-like groups (86% vs. 78%, p = 0.575) but the mortality rate was significantly lower in NIV trial-like group (14% vs. 52%, p = 0.02). Among NIV to HFNC patients, NIV failure was lower in the single switch group compared to the multiple switches group (15% vs. 53%, p = 0.039), with a shorter length of stay (5 [2-8] vs. 12 [8-30] days, p = 0.001).

CONCLUSIONS

NIRS combination is used in real life and both switches' strategies, HFNC to NIV and NIV to HFNC, are common in AHRF management. Transitioning from HFNC to NIV is suggested as a therapeutic escalation and in this context performance of a NIV-trial could be beneficial. Conversely, switching from NIV to HFNC is suggested as a de-escalation strategy that is deemed safe if there is no NIRS failure.

Clinical Practice of High-Flow Nasal Cannula Therapy in ARDS Patients: A Cross-Sectional Survey of Respiratory Therapists

Background

High-flow nasal cannula (HFNC) is an essential non-invasive oxygen therapy in acute respiratory distress syndrome (ARDS) patients. Despite its wide use, research assessing the knowledge, practice, and barriers to using HFNC among respiratory therapists (RT) is lacking.

Methods

A cross-sectional questionnaire was conducted among RTs in Saudi Arabia between December 19, 2022, and July 15, 2023. Data were analyzed as means and standard deviation or frequency and percentages. A Chi-square test was used to compare the differences between groups.

Results

A total of 1001 RTs completed the online survey. Two-thirds of the respondents 659 (65.8%) had received training in using HFNC and 785 (78.4%) had used HFNC in clinical settings. The top conditions for HFNC indication were COVID-19 (78%), post-extubation (65%), and do-not-intubate patients (64%). Participants strongly agreed that helping maintain conversation and eating abilities (32.95%) and improving shortness of breath (34.1%) were advantages of HFNC. Surprisingly, 568 (57%) of RT staff did not follow a protocol for HFNC with ARDS patients. When starting HFNC, 40.2% of the participants started with FiO2 of 61% to 80%. Additionally, high percentages of RT staff started with a flow rate between 30 L/minute and 40 L/minute (40.6%) and a temperature of 37°C (57.7%). When weaning ARDS patients, 482 (48.1%) recommended first reducing gas flow by 5-10 L/minute every two to four hours. Moreover, 549 (54.8%) believed that ARDS patients could be disconnected from HFNC if they achieved a flow rate of <20 L/minute and FiO2 of <35%. Lack of knowledge was the most common challenge concerning HFNC implementation.

Conclusion

The findings revealed nuanced applications marked by significant endorsement in certain clinical scenarios and a lack of protocol adherence, underscoring the need for uniform, evidence-based guidelines and enhanced training for RTs. Addressing these challenges is pivotal to optimizing the benefits of HFNC across varied clinical contexts.

Lung ultrasound score predicts outcomes in patients with acute respiratory failure secondary to COVID-19 treated with non-invasive respiratory support: a prospective cohort study

BACKGROUND

Lung ultrasound has demonstrated its usefulness in several respiratory diseases management. One derived score, the Lung Ultrasound (LUS) score, is considered a good outcome predictor in patients with Acute Respiratory Failure (ARF). Nevertheless, it has not been tested in patients undergoing non-invasive respiratory support (NIRS). Taking this into account, the aim of this study is to evaluate LUS score as a predictor of 90-day mortality, ETI (Endotracheal intubation) and HFNC (High Flow Nasal Cannula) failure in patients with ARF due to COVID-19 admitted to a Respiratory Intermediate Care Unit (RICU) for NIRS management.

RESULTS

One hundred one patients were admitted to the RICU during the study period. Among these 76% were males and the median age was 55 (45-64) years. Initial ARF management started with HFNC, the next step was the use of Continuous Positive Airway Pressure (CPAP) devices and the last intervention was ETI and Intensive Care Unit (ICU) admission. Of the total study population, CPAP was required in 40%, ETI in 26%, while 15% died. By means of a ROC analysis, a LUS ≥ 25 points was identified as the cut-off point for mortality(AUC 0.81, OR 1.40, 95% CI 1.14 to 1.71; p < 0.001), ETI (AUC 0.83, OR 1.43, 95% CI 1.20 to 1.70; p < 0.001) and HFNC failure (AUC 0.75, OR 1.25, 95% CI 1.12 to 1.41; p < 0.001). Kaplan-Meier survival curves also identified LUS ≥ 25 as a predictor of 90-days mortality (HR 4.16, 95% CI 1.27-13.6) and 30 days ETI as well.

CONCLUSION

In our study, a ≥ 25 point cut-off of the Lung Ultrasound Score was identified as a good outcome prediction factor for 90-days mortality, ETI and HFNC failure in a COVID-19 ARF patients cohort treated in a RICU. Considering that LUS score is easy to calculate, a multicenter study to confirm our findings should be performed.

Oxygen debt as a predictor of high-flow nasal cannula therapy failure in SARS-CoV-2 patients with acute respiratory failure: A retrospective cohort study

BACKGROUND

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is known for its rapid progression to acute hypoxemic respiratory failure (AHRF). The increased use of oxygen therapy during the pandemic and the progression of AHRF have highlighted the need to promptly determine the need for orotracheal intubation (OTI).

OBJETIVE

To determine the validity of quantitative measurement of oxygen debt (DEOx) according to arterial gases compared to the use of iROX in patients with high-flow nasal cannula (HFNC) therapy requirement, presenting with acute respiratory failure as a consequence of SARS-CoV-2 infection. In addition, we aimed to identify the factors associated with the need for orotracheal intubation (OTI).

METHODS

A retrospective observational cohort study of a database collected from patients with SARS-CoV-2 infection admitted to intensive care units with AHRF and had received HFNC upon admission during the Covid-19 pandemic (March 23, 2020 through August 02, 2021). The variables of interest were factors determining the predictive ability of DEOx and iROX. We used a multiple logarithmic regression model to correct for confounding and mixed-effects variables, and validated for OTI in patients treated with HFNC.

RESULTS

From a total of 373 patients treated with HFNC, 317 patients (84.9%) required invasive mechanical ventilation. APACHE II (AOR 1.44; 95% CI: 1.14-1.83, p 0,032), vasopressor use (AOR 27.7; 95% CI: 1.83 - 420,63, p 0,017), and DEOx (AOR 1.26; 95% CI: 1.10 - 1.44, p 0,001) were associated with the need for intubation. The predictive model between iROX and DEOx evidenced an AUC of 0.535 vs. 0.606, respectively, with a DEOx cut off point of 7.14 (±10.16, p < 0.01). DEOx as an independent factor of OTI presents an OR 2,48 with cut point 4.5 mlO2/kg (AUC 0.780, CI 95%, 0.753 - 0.808, p < 0.01).

CONCLUSIONS

DEOx is a valuable measurment to identify the need for OTI in patients with SARS-CoV-2 who were under management with HFNC with a predictive value superior to iROX, being a reproducible and valid quantitative method for the need OTI that can be implemented in other critically illconditions. Further studies are required to characterize the usefulness of DEOx more precisely.

Effectiveness of high flow nasal cannula (HFNC) versus bilevel positive airway pressure (BiPAP) in preventing tracheal reintubation in patients with high risk of extubation failure in intensive care unit - A randomised comparative trial

Background and Aims

The incidence of tracheal extubation failure in high-risk patients is higher, and non-invasive ventilation is suggested to avoid tracheal reintubation. This study compares the effectiveness of bilevel positive airway pressure (BiPAP) and high flow nasal cannula (HFNC) to reduce the rate of reintubation in intensive care unit (ICU) patients with increased risk of extubation failure.

Methods

This randomised comparative trial was conducted on 60 high-risk patients on mechanical ventilators admitted to the ICU, ready for weaning after a spontaneous breathing trial. They were randomised to Group H for HFNC and Group B for BiPAP therapy. Designated therapy was administered in these high-risk patients for up to 48 hours after tracheal extubation. Haemodynamic parameters [mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), a saturation of peripheral oxygen (SpO2), electrocardiogram (ECG)], arterial blood gas analysis (ABG) parameter [potential of hydrogen (pH), partial pressure of carbon dioxide (pCO2), partial pressure of oxygen/fraction of inspired oxygen (paO2/FiO2) ratio], the effectiveness of cough, comfort level was recorded and continuous monitoring for signs of respiratory distress and failure was done.

Results

Most of the patients were obese and had more than two risk factors for extubation failure. Several patients in Group B have significantly higher successful extubation than in Group H (P = 0.044). Most of the reintubation took place within 24 hours. The HFNC therapy was more comfortable and acceptable to patients.

Conclusion

BiPAP therapy was more efficient than HFNC in preventing tracheal reintubation among patients with a high risk of extubation failure.

Comparison of ROX, HROX, and delta-HR indices to predict successful weaning from high-flow oxygen therapy in hospitalized patients with COVID-19 pneumonia

BACKGROUND

High-flow nasal cannula (HFNC) therapy is commonly used to treat acute respiratory failure in patients with COVID-19 pneumonia. However, predictors of successful weaning from HFNC in these patients has not been investigated.

OBJECTIVE

To assess predictors of successful separation from HFNC in patients with COVID-19 pneumonia.

METHODS

We conducted a retrospective cohort study at a university hospital in Thailand. Patients with COVID-19 pneumonia requiring HFNC therapy between April 2020 and June 2022 were included. ROX index was defined as the ratio of oxygen saturation (SpO2) / fraction of inspired oxygen (FiO2) to respiratory rate. Heart-ROX (HROX) index was defined as ROX multiplied by heart rate (HR) improvement. HR improvement (delta-HR) was defined as a percentage of the difference between the baseline HR and the morning HR at HFNC weaning day 1 divided by the baseline HR. Weaning success was defined as ability to sustain spontaneous breathing after separation from HFNC without any invasive or non-invasive ventilatory support for ≥48 hours or death.

RESULTS

A total of 164 patients (54% male) were included. Mean age was 61.1±16.1 years. Baseline SpO2/FiO2 was 265.3±110.8. HFNC weaning success was 77.4%. The best cut-off value of ROX index to predict HFNC weaning success was 7.88 with 100% sensitivity, 97.3% specificity, and area under the ROC curve (AUC) of 0.98 (95% CI: 0.937-1.000, p<0.001). The best cut-off value of delta-HR 3.7 with 88.2% sensitivity, 75.7% specificity, and AUC of 0.83 (95% CI: 0.748-0.919, p<0.001). The best cut-off value of HROX index was 59.2 with 88.2% sensitivity, 81.1% specificity, and AUC of 0.89, (95% CI: 0.835-0.953, p<0.001).

CONCLUSIONS

The ROX index has the highest accuracy for predicting successful weaning off HFNC treatment in patients with COVID-19 pneumonia. While HROX and delta-HR indices can serve as alternative tools, it is recommended to verify these indices and determine the optimal cut-off value for determining separation from HFNC therapy through a large prospective cohort study.

TRIAL REGISTRATION

Clinicaltrials.in.th number: TCTR20221108004.

External validation of the HACOR score and ROX index for predicting treatment failure in patients with coronavirus disease 2019 pneumonia managed on high-flow nasal cannula therapy: a multicenter retrospective observational study in Japan

BACKGROUND

The HACOR score for predicting treatment failure includes vital signs and acid-base balance factors, whereas the ROX index only considers the respiratory rate, oxygen saturation, and fraction of inspired oxygen (FiO2). We aimed to externally validate the HACOR score and ROX index for predicting treatment failure in patients with coronavirus disease 2019 (COVID-19) on high-flow nasal cannula (HFNC) therapy in Japan.

METHODS

This retrospective, observational, multicenter study included patients, aged ≥ 18 years, diagnosed with COVID-19 and treated with HFNC therapy between January 16, 2020, and March 31, 2022. The HACOR score and ROX index were calculated at 2, 6, 12, 24, and 48 h after stating HFNC therapy. The primary outcome was treatment failure (requirement for intubation or occurrence of death within 7 days). We calculated the area under the receiver operating characteristic curve (AUROC) and assessed the diagnostic performance of these indicators. The 2-h time-point prediction was considered the primary analysis and that of other time-points as the secondary analysis. We also assessed 2-h time-point sensitivity and specificity using previously reported cutoff values (HACOR score > 5, ROX index < 2.85).

RESULTS

We analyzed 300 patients from 9 institutions (median age, 60 years; median SpO2/FiO2 ratio at the start of HFNC therapy, 121). Within 7 days of HFNC therapy, treatment failure occurred in 127 (42%) patients. The HACOR score and ROX index at the 2-h time-point exhibited AUROC discrimination values of 0.63 and 0.57 (P = 0.24), respectively. These values varied with temporal changes-0.58 and 0.62 at 6 h, 0.70 and 0.68 at 12 h, 0.68 and 0.69 at 24 h, and 0.75 and 0.75 at 48 h, respectively. The 2-h time-point sensitivity and specificity were 18% and 91% for the HACOR score, respectively, and 3% and 100% for the ROX index, respectively. Visual calibration assessment revealed well calibrated HACOR score, but not ROX index.

CONCLUSIONS

In COVID-19 patients receiving HFNC therapy in Japan, the predictive performance of the HACOR score and ROX index at the 2-h time-point may be inadequate. Furthermore, clinicians should be mindful of time-point scores owing to the variation of the models' predictive performance with the time-point. Trial registration UMIN (registration number: UMIN000050024, January 13, 2023).

Increased bronchiolitis burden and severity after the pandemic: a national multicentric study

BACKGROUND

The coronavirus 2019 (COVID-19) related containment measures led to the disruption of all virus distribution. Bronchiolitis-related hospitalizations shrank during 2020-2021, rebounding to pre-pandemic numbers the following year. This study aims to describe the trend in bronchiolitis-related hospitalization this year, focusing on severity and viral epidemiology.

METHODS

We conducted a retrospective investigation collecting clinical records data from all infants hospitalized for bronchiolitis during winter (1st September-31th March) from September 2018 to March 2023 in six Italian hospitals. No trial registration was necessary according to authorization no.9/2014 of the Italian law.

RESULTS

Nine hundred fifty-three infants were hospitalized for bronchiolitis this last winter, 563 in 2021-2022, 34 in 2020-2021, 395 in 2019-2020 and 483 in 2018-2019. The mean length of stay was significantly longer this year compared to all previous years (mean 7.2 ± 6 days in 2022-2023), compared to 5.7 ± 4 in 2021-2022, 5.3 ± 4 in 2020-2021, 6.4 ± 5 in 2019-2020 and 5.5 ± 4 in 2018-2019 (p < 0.001), respectively. More patients required mechanical ventilation this winter 38 (4%), compared to 6 (1%) in 2021-2022, 0 in 2020-2021, 11 (2%) in 2019-2020 and 6 (1%) in 2018-2019 (p < 0.05), respectively. High-flow nasal cannula and non-invasive respiratory supports were statistically more common last winter (p = 0.001 or less). RSV prevalence and distribution did not differ this winter, but coinfections were more prevalent 307 (42%), 138 (31%) in 2021-2022, 1 (33%) in 2020-2021, 68 (23%) in 2019-2020, 61 (28%) in 2018-2019 (p = 0.001).

CONCLUSIONS

This study shows a growth of nearly 70% in hospitalisations for bronchiolitis, and an increase in invasive respiratory support and coinfections, suggesting a more severe disease course this winter compared to the last five years.

Oxygenation during Endobronchial Ultrasound: Where do we stand?

NONE

Relationship between the Pre-ECMO and ECMO Time and Survival of Severe COVID-19 Patients: A Systematic Review and Meta-Analysis

BACKGROUND

Coronavirus disease 2019 (COVID-19) is the etiology of acute respiratory distress syndrome (ARDS). Extracorporeal membrane oxygenation (ECMO) is used to support gas exchange in patients who have failed conventional mechanical ventilation. However, there is no clear consensus on the timing of ECMO use in severe COVID-19 patients.

OBJECTIVE

The aim of this study is to compare the differences in pre-ECMO time and ECMO duration between COVID-19 survivors and non-survivors and to explore the association between them.

METHODS

PubMed, the Cochrane Library, Embase, and other sources were searched until 21 October 2022. Studies reporting the relationship between ECMO-related time and COVID-19 survival were included. All available data were pooled using random-effects methods. Linear regression analysis was used to determine the correlation between pre-ECMO time and ECMO duration. The meta-analysis was registered with PROSPERO under registration number CRD42023403236.

RESULTS

Out of the initial 2473 citations, we analyzed 318 full-text articles, and 54 studies were included, involving 13,691 patients. There were significant differences between survivors and non-survivors in the time from COVID-19 diagnosis (standardized mean difference (SMD) = -0.41, 95% confidence interval (CI): [-0.53, -0.29], p < 0.00001), hospital (SMD = -0.53, 95% CI: [-0.97, -0.09], p = 0.02) and intensive care unit (ICU) admission (SMD = -0.28, 95% CI: [-0.49, -0.08], p = 0.007), intubation or mechanical ventilation to ECMO (SMD = -0.21, 95% CI: [-0.32, -0.09], p = 0.0003) and ECMO duration (SMD = -0.18, 95% CI: [-0.30, -0.06], p = 0.003). There was no statistical association between a longer time from symptom onset to ECMO (hazard ratio (HR) = 1.05, 95% CI: [0.99, 1.12], p = 0.11) or time from intubation or mechanical ventilation (MV) and the risk of mortality (highest vs. lowest time groups odds ratio (OR) = 1.18, 95% CI: [0.78, 1.78], p = 0.42; per one-day increase OR = 1.14, 95% CI: [0.86, 1.52], p = 0.36; HR = 0.99, 95% CI: [0.95, 1.02], p = 0.39). There was no linear relationship between pre-ECMO time and ECMO duration.

CONCLUSION

There are differences in pre-ECMO time between COVID-19 survivors and non-survivors, and there is insufficient evidence to conclude that longer pre-ECMO time is responsible for reduced survival in COVID-19 patients. ECMO duration differed between survivors and non-survivors, and the timing of pre-ECMO does not have an impact on ECMO duration. Further studies are needed to explore the association between pre-ECMO and ECMO time in the survival of COVID-19 patients.

Machine learning prediction of the failure of high-flow nasal oxygen therapy in patients with acute respiratory failure

Acute respiratory failure (ARF) is a prevalent and serious condition in intensive care unit (ICU), often associated with high mortality rates. High-flow nasal oxygen (HFNO) therapy has gained popularity for treating ARF in recent years. However, there is a limited understanding of the factors that predict HFNO failure in ARF patients. This study aimed to explore early indicators of HFNO failure in ARF patients, utilizing machine learning (ML) algorithms to more accurately pinpoint individuals at elevated risk of HFNO failure. Utilizing ML algorithms, we developed seven predictive models. Their performance was evaluated using various metrics, including the area under the receiver operating characteristic curve, calibration curve, and precision recall curve. The study enrolled 700 patients, with 490 in the training group and 210 in the validation group. The overall HFNO failure rate was 14.1% among the 700 patients. The ML algorithms demonstrated robust performance in our study. This research underscores the potential of ML techniques in creating clinically relevant models for predicting HFNO outcomes in ARF patients. These models could play a pivotal role in enhancing the risk management of HFNO, leading to more patient-centered and personalized care approaches.

ROX index performance to predict high-flow nasal oxygen outcome in Covid-19 related hypoxemic acute respiratory failure

BACKGROUND

Given the pathophysiology of hypoxemia in patients with Covid-19 acute respiratory failure (ARF), it seemed necessary to evaluate whether ROX index (ratio SpO2/FiO2 to respiratory rate) could accurately predict intubation or death in these patients initially treated by high-flow nasal oxygenation (HFNO). We aimed, therefore, to assess the accuracy of ROX index to discriminate between HFNO failure (sensitivity) and HFNO success (specificity).

METHODS

We designed a multicentre retrospective cohort study including consecutive patients with Covid-19 ARF. In addition to its accuracy, we assessed the usefulness of ROX index to predict HFNO failure (intubation or death) via logistic regression.

RESULTS

Among 218 ARF patients screened, 99 were first treated with HFNO, including 49 HFNO failures (46 intubations, 3 deaths before intubation). At HFNO initiation (H0), ROX index sensitivity was 63% (95%CI 48-77%) and specificity 76% (95%CI 62-87%) using Youden's index. With 4.88 as ROX index cut-off at H12, sensitivity was 29% (95%CI 14-48%) and specificity 90% (95%CI 78-97%). Youden's index yielded 8.73 as ROX index cut-off at H12, with 87% sensitivity (95%CI 70-96%) and 45% specificity (95%CI 31-60%). ROX index at H0 was associated with HFNO failure (p = 0.0005) in univariate analysis. Multivariate analysis showed that SAPS II (p = 0.0003) and radiographic extension of pulmonary injuries (p = 0.0263), rather than ROX index, were predictive of HFNO failure.

CONCLUSIONS

ROX index cut-off values seem population-specific and the ROX index appears to have a technically acceptable but clinically low capability to discriminate between HFNO failures and successes in Covid-19 ARF patients. In addition, SAPS II and pulmonary injuries at ICU admission appear more useful than ROX index to predict the risk of intubation.

Predicting invasive mechanical ventilation in COVID 19 patients: A validation study

INTRODUCTION

The decision to intubate and ventilate a patient is mainly clinical. Both delaying intubation (when needed) and unnecessarily invasively ventilating (when it can be avoided) are harmful. We recently developed an algorithm predicting respiratory failure and invasive mechanical ventilation in COVID-19 patients. This is an internal validation study of this model, which also suggests a categorized "time-weighted" model.

METHODS

We used a dataset of COVID-19 patients who were admitted to Rabin Medical Center after the algorithm was developed. We evaluated model performance in predicting ventilation, regarding the actual endpoint of each patient. We further categorized each patient into one of four categories, based on the strength of the prediction of ventilation over time. We evaluated this categorized model performance regarding the actual endpoint of each patient.

RESULTS

881 patients were included in the study; 96 of them were ventilated. AUC of the original algorithm is 0.87-0.94. The AUC of the categorized model is 0.95.

CONCLUSIONS

A minor degradation in the algorithm accuracy was noted in the internal validation, however, its accuracy remained high. The categorized model allows accurate prediction over time, with very high negative predictive value.

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

BACKGROUND

The predictive value of the respiratory rate‑oxygenation (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.

Safety and Outcome of High-Flow Nasal Oxygen Therapy Outside ICU Setting in Hypoxemic Patients With COVID-19

OBJECTIVE

High-flow nasal oxygen (HFNO) therapy is frequently applied outside ICU setting in hypoxemic patients with COVID-19. However, safety concerns limit more widespread use. We aimed to assess the safety and clinical outcomes of initiation of HFNO therapy in COVID-19 on non-ICU wards.

DESIGN

Prospective observational multicenter pragmatic study.

SETTING

Respiratory wards and ICUs of 10 hospitals in The Netherlands.

PATIENTS

Adult patients treated with HFNO for COVID-19-associated hypoxemia between December 2020 and July 2021 were included. Patients with treatment limitations were excluded from this analysis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Outcomes included intubation and mortality rate, duration of hospital and ICU stay, severity of respiratory failure, and complications. Using propensity-matched analysis, we compared patients who initiated HFNO on the wards versus those in ICU. Six hundred eight patients were included, of whom 379 started HFNO on the ward and 229 in the ICU. The intubation rate in the matched cohort ( n = 214 patients) was 53% and 60% in ward and ICU starters, respectively ( p = 0.41). Mortality rates were comparable between groups (28-d [8% vs 13%], p = 0.28). ICU-free days were significantly higher in ward starters (21 vs 17 d, p < 0.001). No patient died before endotracheal intubation, and the severity of respiratory failure surrounding invasive ventilation and clinical outcomes did not differ between intubated ward and ICU starters (respiratory rate-oxygenation index 3.20 vs 3.38; Pa o2 :F io2 ratio 65 vs 64 mm Hg; prone positioning after intubation 81 vs 78%; mortality rate 17 vs 25% and ventilator-free days at 28 d 15 vs 13 d, all p values > 0.05).

CONCLUSIONS

In this large cohort of hypoxemic patients with COVID-19, initiation of HFNO outside the ICU was safe, and clinical outcomes were similar to initiation in the ICU. Furthermore, the initiation of HFNO on wards saved time in ICU without excess mortality or complicated course. Our results indicate that HFNO initiation outside ICU should be further explored in other hypoxemic diseases and clinical settings aiming to preserve ICU capacity and healthcare costs.

Ventilatory Management of Patients with Acute Respiratory Distress Syndrome Due to SARS-CoV-2

The emergence of the new SARS-CoV-2 in December 2019 caused a worldwide pandemic of the resultant disease, COVID-19. There was a massive surge in admissions to intensive care units (ICU), notably of patients with hypoxaemic acute respiratory failure. In these patients, optimal oxygen therapy was crucial. In this article, we discuss tracheal intubation to provide mechanical ventilation in patients with hypoxaemic acute respiratory failure due to SARS-CoV-2. We first describe the pathophysiology of respiratory anomalies leading to acute respiratory distress syndrome (ARDS) due to infection with SARS-CoV-2, and then briefly review management, focusing particularly on the ventilation strategy. Overall, the ventilatory management of ARDS due to SARS-CoV-2 infection is largely the same as that applied in ARDS from other causes, and lung-protective ventilation is recommended. The difference lies in the initial clinical presentation, with profound hypoxaemia often observed concomitantly with near-normal pulmonary compliance.

Associations of Awake Prone Positioning-Induced Changes in Physiology with Intubation: An International Prospective Observational Study in Patients with Acute Hypoxemic Respiratory Failure Related to COVID-19

INTRODUCTION

Awake prone positioning has the potential to improve oxygenation and decrease respiratory rate, potentially reducing the need for intubation in patients with acute hypoxemic respiratory failure. We investigated awake prone positioning-induced changes in oxygenation and respiratory rate, and the prognostic capacity for intubation in patients with COVID-19 pneumonia.

METHODS

International multicenter prospective observation study in critically ill adult patients with COVID-19 receiving supplemental oxygen. We collected data on oxygenation and respiratory rate at baseline, and at 1 h after being placed in prone positioning. The combined primary outcome was oxygenation and respiratory rate at 1 h. The secondary endpoint was treatment failure, defined as need for intubation within 24 h of start of awake prone positioning.

RESULTS

Between March 27th and November 2020, 101 patients were enrolled of which 99 were fully analyzable. Awake prone positioning lasted mean of 3 [2-4] h. In 77 patients (77.7%), awake prone positioning improved oxygenation, and in 37 patients (54.4%) it decreased respiratory rate. Twenty-nine patients (29.3%) were intubated within 24 h. An increase in SpO2/FiO2 of < 10 (OR 5.1, 95% CI 1.4-18.5, P = 0.01), a failure to increase PaO2/FiO2 to > 116 mmHg (OR 3.6, 95% CI 1.2-10.8, P = 0.02), and a decrease in respiratory rate of < 2 breaths/min (OR 3.6, 95% CI 1.3-9.5, P = 0.01) were independent variables associated with need for intubation. The AUC-ROC curve for intubation using a multivariable model was 0.73 (95% CI 0.62-0.84).

CONCLUSIONS

Awake prone positioning improves oxygenation in the majority of patients, and decreases respiratory rate in more than half of patients with acute hypoxemic respiratory failure caused by COVID-19. One in three patients need intubation within 24 h. Awake prone position-induced changes in oxygenation and respiratory rate have prognostic capacity for intubation within 24 h.

Effect of noninvasive respiratory support on interstitial lung disease with acute respiratory failure: A systematic review and meta-analysis

Background

Primary studies have demonstrated the effectiveness of noninvasive respiratory supports, including noninvasive positive pressure ventilation (NIPPV) and high flow nasal cannula (HFNC), for improving oxygenation and ventilation in patients with interstitial lung diseases (ILDs) and acute respiratory failure (ARF). These studies have not been synthesized and are not included in current practice guidelines. This systematic review with meta-analysis synthesizes studies that compared the effectiveness of NIPPV, HFNC and conventional oxygen therapy (COT) for improving oxygenation and ventilation in ILD patients with ARF.

Methods

MEDLINE, EMBASE and the Cochrane Library searches were conducted from inception to August 2023. An additional search of relevant primary literature and review articles was also performed. A random effects model was used to estimate the PF ratio (ratio of arterial oxygen partial pressure to fractional inspired oxygen), PaCO2 (partial pressure of carbon dioxide), mortality, intubation rate and hospital length of stay.

Results

Ten studies were included in the systematic review and meta-analysis. Noninvasive respiratory supports demonstrated a significant improvement in PF ratio compared to conventional oxygen therapy (COT); the mean difference was 55.92 (95% CI [18.85-92.99]; p=0.003). Compared to HFNC, there was a significant increase in PF ratio in NIPPV (mean difference 0.45; 95% CI [0.12-0.79]; p=0.008). There were no mortality and intubation rate benefits when comparing NIPPV and HFNC; the mean difference was 1.1; 95% CI [0.83-1.44]; p=0.51 and 1.86; 95% CI [0.42-8.33]; p=0.42, respectively. In addition, there was a significant decrease in hospital length of stay in HFNC compared to NIPPV (mean difference 9.27; 95% Cl [1.45 - 17.1]; p=0.02).

Conclusions

Noninvasive respiratory supports might be an alternative modality in ILDs with ARF. NIPPV demonstrated a potential to improve the PF ratio compared to HFNC. There was no evidence to support the benefit of NIPPV or HFNC in terms of mortality and intubation rate.

High flow nasal oxygen in frail COVID-19 patients hospitalized in intermediate care units and non-eligible to invasive mechanical ventilation

BACKGROUND

In COVID-19 patients, older age (sixty or older), comorbidities, and frailty are associated with a higher risk for mortality and invasive mechanical ventilation (IMV) failure. It therefore seems appropriate to suggest limitations of care to older and vulnerable patients with severe COVID-19 pneumonia and a poor expected outcome, who would not benefit from invasive treatment. HFNO (high flow nasal oxygen) is a non-invasive respiratory support device already used in de novo acute respiratory failure. The main objective of this study was to evaluate the survival of patients treated with HFNO outside the ICU (intensive care unit) for a severe COVID-19 pneumonia, otherwise presenting limitations of care making them non-eligible for IMV. Secondary objectives were the description of our cohort and the identification of prognostic factors for HFNO failure.

METHODS

We conducted a retrospective cohort study. We included all patients with limitations of care making them non-eligible for IMV and treated with HFNO for a severe COVID-19 pneumonia, hospitalized in a COVID-19 unit of the pulmonology department of Lyon Sud University Hospital, France, from March 2020 to March 2021. Primary outcome was the description of the vital status at day-30 after HFNO initiation, using the WHO (World Health Organization) 7-points ordinal scale.

RESULTS

Fifty-six patients were included. Median age was 83 years [76.3-87.0], mean duration for HFNO was 7.5 days, 53% had a CFS score (Clinical Frailty Scale) >4. At day-30, 73% of patients were deceased, one patient (2%) was undergoing HFNO, 9% of patients were discharged from hospital. HFNO failure occurred in 66% of patients. Clinical signs of respiratory failure before HFNO initiation (respiratory rate >30/min, retractions, and abdominal paradoxical breathing pattern) were associated with mortality (p = 0.001).

CONCLUSIONS

We suggest that HFNO is an option in non-ICU skilled units for older and frail patients with a severe COVID-19 pneumonia, otherwise non-suitable for intensive care and mechanical ventilation. Observation of clinical signs of respiratory failure before HFNO initiation was associated with mortality.

[Ventilatory management of SARS-CoV-2 acute respiratory failure]

COVID-19 pneumonia presents several particularities in its clinical presentation (cytokine storm, silent hypoxemia, thrombo-embolic risk) and may lead to a number of acute respiratory distress syndrome (ARDS) phenotypes. While the optimal oxygenation strategy in cases of hypoxemic acute respiratory failure (ARF) is still under debate, ventilatory management of COVID-19-related ARF has confirmed the efficacy of high-flow oxygen therapy and restored interest in other ventilatory approaches such as continuous positive airway pressure (CPAP) and noninvasive ventilation involving a helmet, which due to patient overflow are sometimes implemented outside of critical care units. However, further studies are still needed to determine which patients should be given which oxygenation technique, and under which conditions they require invasive mechanical ventilation, given that delayed initiation potentially burdens prognosis. During invasive mechanical ventilation, ventral decubitus and extracorporeal membrane oxygenation have become increasingly prevalent. While innovative therapies such as awake prone position or lung transplantation have likewise been developed, their indications, modalities and efficacy remain to be determined.

Long-term survival comparison between the first and second waves among 265 critical COVID-19 patients admitted to the ICU: A retrospective cohort study

BACKGROUD

Management of severe COVID-19 patients admitted to ICU considerably evolved during the first months of the pandemic. It is unclear, however, whether these changes improved long-term survival of these critically ill patients.

METHODS

We conducted a retrospective cohort study in adults with COVID-19 pneumonia admitted to a French ICU between February 2020 and January 2021, a timeframe that covered the first two waves of the pandemic. Primary outcome was to compare long-term survival between the first and second waves. Survival predictor were identified using a Cox proportional-hazards model.

RESULTS

We included 265 patients in the cohort: 140 (52.8 %) and 125 (47.2 %) belonging to the first and second waves, respectively. Baseline characteristics of the patients were similar between the two waves. During W2, use of early corticotherapy increased (86.4% vs. 17.8 %; p <0.001), as well as high-flow oxygen therapy use (68.5% vs. 37.4 %; p<0.001). Need for invasive mechanical ventilation decreased (49.6% vs. 72.9 %; p <0.001) and ICU length of stay was shorter (11 [6-22] vs 19 [8-32]days; p = 0.008). ICU mortality was 32.8 % without significant difference between waves. Survival analysis revealed that 3 variables were independently associated with a worse long-term prognosis: a higher SAPS II score (1.05 [1.04-1.06]; p<0.001), a higher age (1.05 [1.01-1.08]; p = 0.005) and admission during W2 (2.22 [1.15-4.28]; p = 0.017).

DISCUSSION

Despite substantial changes on management of severe COVID-19 patients, we observed a decreased long-term survival among patients admitted during the second wave. We also noted a shorter ICU length of stay.

Diaphragm excursions as proxy for tidal volume during spontaneous breathing in invasively ventilated ICU patients

There is a need to monitor tidal volume in critically ill patients with acute respiratory failure, given its relation with adverse clinical outcome. However, quantification of tidal volume in non-intubated patients is challenging. In this proof-of-concept study, we evaluated whether ultrasound measurements of diaphragm excursion could be a valid surrogate for tidal volume in patients with respiratory failure. Diaphragm excursions and tidal volumes were simultaneously measured in invasively ventilated patients (N = 21) and healthy volunteers (N = 20). Linear mixed models were used to estimate the ratio between tidal volume and diaphragm excursion. The tidal volume-diaphragm excursion ratio was 201 mL/cm in ICU patients [95% confidence interval (CI) 161-240 mL/cm], and 361 (294-428) mL/cm in healthy volunteers. An excellent association was shown within participants (R2 = 0.96 in ICU patients, R2 = 0.90 in healthy volunteers). However, the differences between observed tidal volume and tidal volume as predicted by the linear mixed models were considerable: the 95% limits of agreement in Bland-Altman plots were ± 91 mL in ICU patients and ± 396 mL in healthy volunteers. Likewise, the variability in tidal volume estimation between participants was large. This study shows that diaphragm excursions measured with ultrasound correlate with tidal volume, yet quantification of absolute tidal volume from diaphragm excursion is unreliable.

Application of 24-h respiratory rate and oxygenation index variation to predict the outcome of high-flow nasal cannula therapy in patients with acute hypoxemic respiratory failure in a respiratory intensive care unit

Background: An evaluation system is urgently needed to describe early predictors of the outcome of high-flow nasal cannula (HFNC) oxygen therapy in acute hypoxemic respiratory failure (AHRF) patients. Methods: All consecutive AHRF patients in a Respiratory Intensive Care Unit (RICU) receiving HFNC therapy between January 2019 and December 2021 were enrolled. Results: Of the 106 enrolled AHRF subjects, 57 (53.8%) succeeded in HFNC therapy and 49 (46.2%) failed. Being male (p = 0.006), initial respiratory rate oxygenation (ROX) index (p = 0.011), Acute Physiology and Chronic Health Evaluation II score (p = 0.007) and 24-h ROX index variation rate (p = 0.004) were independent factors of HFNC outcome; among these, 24-h ROX index variation rate (area under the curve = 0.825) was the best evaluation indicator. Conclusion: 24-h ROX index variation rate, introduced by our study, has shown the best potential to predict HFNC outcome in AHRF patients.

Early Versus Late Endotracheal Intubation in Subjects with COVID-19 Pneumonia Treated with High-Flow Oxygen: A Retrospective Observational Study

INTRODUCTION

The availability of high-flow oxygen (HFO) machines allowed patients with COVID-19 pneumonia to be comfortably treated for longer periods of time until endotracheal intubation became inevitable. Patients treated with invasive mechanical ventilation (MV) preceded by HFO treatment may continue to progress and die. Hence there is a belief in physicians that patients treated with HFO might have delayed invasive MV.

METHODS

The study was conducted as a retrospective review of subjects with confirmed COVID-19 admitted to the Dubai Hospital ICU. Study variables included time to intubation, duration of HFO, and cumulative duration of tachypnea and tachycardia while on HFO usage. Early intubation was defined as within 24 hours of the start of HFO, and late intubation was defined as after seven days on HFO. Groups were compared for outcome measures; mortality and length of stay (LOS) in the ICU and hospital.

RESULTS

Clinical outcomes of mortality and LOS in ICU and hospital were not significantly different among patients intubated early versus late. Duration of tachypnea and tachycardia was also not different comparing patients intubated early versus late.

CONCLUSION

There was no significant difference in clinical outcomes in patients intubated early versus late in patients treated with HFO for COVID-19 pneumonia.

Ultrasonographic evaluation of the diaphragm in critically ill patients to predict invasive mechanical ventilation

BACKGROUND

Diaphragm dysfunction is common in critically ill patients and associated with poorer outcomes. The function of the diaphragm can be evaluated at the bedside by measuring diaphragmatic excursion using ultrasonography. In this study, we investigated the ability of right-sided diaphragmatic excursion (RDE) to predict the need for invasive mechanical ventilation (IMV).

METHODS

Critically ill patients aged 18 years and older who presented to our emergency department between May 20, 2021 and May 19, 2022 and underwent measurement of RDE within 10 min of arrival were enrolled in this prospective study. The ability of RDE to predict the need for IMV was assessed by multivariable logistic regression and analysis of the area under the receiver-operating characteristic curve (AUROC).

RESULTS

A total of 314 patients were enrolled in the study; 113 (35.9%) of these patients required IMV. An increase of RDE value per each 0.1 cm was identified to be an independent predictor of IMV (adjusted odds ratio 0.08, 95% confidence interval [CI] 0.04-0.17, p < 0.001; AUROC 0.850, 95% CI 0.807-0.894). The RDE cutoff value was 1.2 cm (sensitivity 82.3%, 95% CI 74.0-88.8; specificity 78.1%, 95% CI 71.7-83.6). Time on a ventilator was significantly longer when the RDE was ≤ 1.2 cm (13 days [interquartile range 5, 27] versus 5 days [interquartile range 3, 8], p = 0.006).

CONCLUSIONS

In this study, RDE had a good ability to predict the need for IMV in critically ill patients. The optimal RDE cutoff value was 1.2 cm. Its benefit in patient management requires further investigation.

Comparison of High Flow Nasal Cannula and Continuous Positive Airway Pressure in COVID-19 Patients With Acute Respiratory Distress Syndrome in Critical Care Unit: A Randomized Control Study

Background and objective Acute hypoxic respiratory failure in coronavirus disease 2019 (COVID-19) pneumonia has been treated with oxygen delivered by oxygen masks and non-invasive ventilation (NIV) with continuous positive airway pressure (CPAP), and more recently with high-flow nasal cannula (HFNC) devices. There is a paucity of randomized controlled trials to compare the efficacy of CPAP with HFNC in COVID-19 pneumonia. We conceptualized a randomized control study to compare the efficacy of HFNC and CPAP in reducing the need for invasive mechanical ventilation, estimation of mechanical ventilation-free days, and risk of intubation in COVID-19 patients with hypoxic respiratory failure. Methodology One hundred consecutive patients who satisfied the inclusion criteria were included in the trial. The patients were then randomly allocated to receive either CPAP or HFNC with settings as per the study protocol. The patients were deemed to have achieved the study endpoint when they were intubated due to any reason or successfully weaned from NIV to conventional oxygen therapies. The number of patients who required invasive ventilation and the number of invasive ventilation-free days were recorded and analyzed. Results Nineteen (38%) patients in the CPAP group and 30 (60%) patients in the HFNC group required invasive mechanical ventilation and the difference was statistically significant (p = 0.03, 95%CI: 0.1829-0.9129). The median number of days free of invasive mechanical ventilation in the CPAP group (median=5 (interquartile range (IQR(=5,6)) was more than in the HFNC group (median=4 (IQR=3,4)) and this difference was statistically significant (p<0.000). The secondary analysis of risk evaluation for intubation done using the Cox regression model showed no significant factors that could have contributed to intubation in the study population. The Kaplan-Meyer curve was used to express the probability of a patient getting intubated and the calculated hazard ratio was 2.29. Conclusion The administration of CPAP significantly reduced the intubation rate and prolonged invasive mechanical ventilation-free period in COVID-19 patients with hypoxic respiratory failure. We also inferred a two-fold increase in the risk of intubation in patients receiving HFNC compared to CPAP.

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.

Physiological effects of awake prone position in acute hypoxemic respiratory failure

BACKGROUND

The effects of awake prone position on the breathing pattern of hypoxemic patients need to be better understood. We conducted a crossover trial to assess the physiological effects of awake prone position in patients with acute hypoxemic respiratory failure.

METHODS

Fifteen patients with acute hypoxemic respiratory failure and PaO2/FiO2 < 200 mmHg underwent high-flow nasal oxygen for 1 h in supine position and 2 h in prone position, followed by a final 1-h supine phase. At the end of each study phase, the following parameters were measured: arterial blood gases, inspiratory effort (ΔPES), transpulmonary driving pressure (ΔPL), respiratory rate and esophageal pressure simplified pressure-time product per minute (sPTPES) by esophageal manometry, tidal volume (VT), end-expiratory lung impedance (EELI), lung compliance, airway resistance, time constant, dynamic strain (VT/EELI) and pendelluft extent through electrical impedance tomography.

RESULTS

Compared to supine position, prone position increased PaO2/FiO2 (median [Interquartile range] 104 mmHg [76-129] vs. 74 [69-93], p < 0.001), reduced respiratory rate (24 breaths/min [22-26] vs. 27 [26-30], p = 0.05) and increased ΔPES (12 cmH2O [11-13] vs. 9 [8-12], p = 0.04) with similar sPTPES (131 [75-154] cmH2O s min-1 vs. 105 [81-129], p > 0.99) and ΔPL (9 [7-11] cmH2O vs. 8 [5-9], p = 0.17). Airway resistance and time constant were higher in prone vs. supine position (9 cmH2O s arbitrary units-3 [4-11] vs. 6 [4-9], p = 0.05; 0.53 s [0.32-61] vs. 0.40 [0.37-0.44], p = 0.03). Prone position increased EELI (3887 arbitrary units [3414-8547] vs. 1456 [959-2420], p = 0.002) and promoted VT distribution towards dorsal lung regions without affecting VT size and lung compliance: this generated lower dynamic strain (0.21 [0.16-0.24] vs. 0.38 [0.30-0.49], p = 0.004). The magnitude of pendelluft phenomenon was not different between study phases (55% [7-57] of VT in prone vs. 31% [14-55] in supine position, p > 0.99).

CONCLUSIONS

Prone position improves oxygenation, increases EELI and promotes VT distribution towards dependent lung regions without affecting VT size, ΔPL, lung compliance and pendelluft magnitude. Prone position reduces respiratory rate and increases ΔPES because of positional increases in airway resistance and prolonged expiratory time. Because high ΔPES is the main mechanistic determinant of self-inflicted lung injury, caution may be needed in using awake prone position in patients exhibiting intense ΔPES. Clinical trail registeration: The study was registered on clinicaltrials.gov (NCT03095300) on March 29, 2017.

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.

Modified Respiratory Rate Oxygenation Index: An Early Warning Index for the Need of Intubation in COVID-19 Patients with High-Flow Nasal Cannula Therapy

BACKGROUND

High-flow nasal cannula oxygen therapy (HFNC) is recommended for patients with COVID-19. However, the increasing use of HFNC brings a risk of delayed intubation. The optimal timing of switching from HFNC to invasive mechanical ventilation (IMV) remains unclear. An effective predictor is needed to assist in deciding on the timing of intubation. Respiratory rate and oxygenation (ROX) index, defined as (SpO2/FiO2) / respiratory rate, has already shown good diagnostic accuracy. Modified ROX (mROX) index, defined as (PaO2 /FiO2) / respiratory rate, might be better than the ROX index in predicting HFNC failure.

OBJECTIVE

The aim was to evaluate the predictive value of mROX for HFNC failure in patients with COVID-19.

METHODS

Severe or critical patients with COVID-19 treated with HFNC were enrolled in two clinical centers. Laboratory indicators, respiratory parameters, and mROX index at 0 h and 2 h after initial HFNC were collected. Based on the need for IMV after HFNC initiation, the patients were divided into an HFNC failure group and an HFNC success group. The predictive value of mROX index for IMV was evaluated by the area under the receiver operating characteristic curve (AUROC) and logistic regression analysis. We performed Kaplan-Meier survival analysis using the log-rank test.

RESULTS

Sixty patients with COVID-19 (mean ± SD age, 62.8 ± 14.1 years; 42 patients were male) receiving HFNC were evaluated, including 18 critical and 42 severe cases. A total of 33 patients had hypertension; 14 had diabetes; 17 had chronic cardiac disease; 11 had chronic lung disease; 13 had chronic kidney disease; and 17 had a history of stroke. The AUROC of mROX index at 2 h was superior to that of other respiratory parameters to predict the need for IMV (0.959; p < 0.001). At the mROX index cutoff point of 4.45, predicting HFNC failure reached the optimal threshold, with specificity of 94% and sensitivity of 92%. Logistic regression analysis showed that 2-h mROX index < 4.45 was a protective factor for IMV (odd radio 0.18; 95% CI 0.05-0.64; p = 0.008). In the HFNC failure group, the median time from HFNC to IMV was 22.5 h. The 28-day mortality of the late intubation patients (≥ 22.5 h) was higher than that of the early intubation patients (< 22.5 h) (53.8% vs. 8.3%; p = 0.023).

CONCLUSIONS

mROX at 2 h is a good early warning index of the need for IMV in patients with COVID-19 after HFNC initiation. Early intubation may lead to better survival in patients with 2-h mROX index < 4.45.

Effect of high-flow nasal cannula versus non-invasive ventilation after extubation on successful extubation in obese patients: a retrospective analysis of the MIMIC-IV database

BACKGROUND

The pathophysiological characteristics of the respiratory system of obese patients differ from those of non-obese patients. Few studies have evaluated the effects of high-flow nasal cannula (HFNC) and non-invasive ventilation (NIV) on the prognosis of obese patients. We here compared the effects of these two techniques on the prevention of reintubation after extubation for obese patients.

METHODS

Data were extracted from the Medical Information Mart for Intensive Care database. Patients who underwent HFNC or NIV treatment after extubation were assigned to the HFNC or NIV group, respectively. The reintubation risk within 96 hours postextubation was compared between the two groups using a doubly robust estimation method. Propensity score matching was performed for both groups.

RESULTS

This study included 757 patients (HFNC group: n=282; NIV group: n=475). There was no significant difference in the risk of reintubation within 96 hours after extubation for the HFNC group compared with the NIV group (OR 1.50, p=0.127). Among patients with body mass index ≥40 kg/m2, the HFNC group had a significantly lower risk of reintubation within 96 hours after extubation (OR 0.06, p=0.016). No significant differences were found in reintubation rates within 48 hours (15.6% vs 11.0%, p=0.314) and 72 hours (16.9% vs 13.0%, p=0.424), as well as in hospital mortality (3.2% vs 5.2%, p=0.571) and intensive care unit (ICU) mortality (1.3% vs 5.2%, p=0.108) between the two groups. However, the HFNC group had significantly longer hospital stays (14 days vs 9 days, p=0.005) and ICU (7 days vs 5 days, p=0.001) stays.

CONCLUSIONS

This study suggests that HFNC therapy is not inferior to NIV in preventing reintubation in obese patients and appears to be advantageous in severely obese patients. However, HFNC is associated with significantly longer hospital stays and ICU stays.

Acute dyspnea in the emergency department: a clinical review

Acute dyspnea represents one of the most frequent symptoms leading to emergency room evaluation. Its significant prognostic value warrants a careful evaluation. The differential diagnosis of dyspnea is complex due to the lack of specificity and the loose association between its intensity and the severity of the underlying pathological condition. The initial assessment of dyspnea calls for prompt diagnostic evaluation and identification of optimal monitoring strategy and provides information useful to allocate the patient to the most appropriate setting of care. In recent years, accumulating evidence indicated that lung ultrasound, along with echocardiography, represents the first rapid and non-invasive line of assessment that accurately differentiates heart, lung or extra-pulmonary involvement in patients with dyspnea. Moreover, non-invasive respiratory support modalities such as high-flow nasal oxygen and continuous positive airway pressure have aroused major clinical interest, in light of their efficacy and practicality to treat patients with dyspnea requiring ventilatory support, without using invasive mechanical ventilation. This clinical review is focused on the pathophysiology of acute dyspnea, on its clinical presentation and evaluation, including ultrasound-based diagnostic workup, and on available non-invasive modalities of respiratory support that may be required in patients with acute dyspnea secondary or associated with respiratory failure.

Development and validation of a prediction model for mechanical ventilation based on comorbidities in hospitalized patients with COVID-19

Background

Timely recognition of respiratory failure and the need for mechanical ventilation is crucial in managing patients with coronavirus disease 2019 (COVID-19) and reducing hospital mortality rate. A risk stratification tool could assist to avoid clinical deterioration of patients with COVID-19 and optimize allocation of scarce resources. Therefore, we aimed to develop a prediction model for early identification of patients with COVID-19 who may require mechanical ventilation.

Methods

We included patients with COVID-19 hospitalized in United States. Demographic and clinical data were extracted from the records of the Healthcare Cost and Utilization Project State Inpatient Database in 2020. Model construction involved the use of the least absolute shrinkage and selection operator and multivariable logistic regression. The model's performance was evaluated based on discrimination, calibration, and clinical utility.

Results

The training set comprised 73,957 patients (5,971 requiring mechanical ventilation), whereas the validation set included 10,428 (887 requiring mechanical ventilation). The prediction model incorporating age, sex, and 11 other comorbidities (deficiency anemias, congestive heart failure, coagulopathy, dementia, diabetes with chronic complications, complicated hypertension, neurological disorders unaffecting movement, obesity, pulmonary circulation disease, severe renal failure, and weight loss) demonstrated moderate discrimination (area under the curve, 0.715; 95% confidence interval, 0.709-0.722), good calibration (Brier score = 0.070, slope = 1, intercept = 0) and a clinical net benefit with a threshold probability ranged from 2 to 34% in the training set. Similar model's performances were observed in the validation set.

Conclusion

A robust prognostic model utilizing readily available predictors at hospital admission was developed for the early identification of patients with COVID-19 who may require mechanical ventilation. Application of this model could support clinical decision-making to optimize patient management and resource allocation.

Timing of invasive mechanical ventilation and death in critically ill adults with COVID-19: A multicenter cohort study

PURPOSE

To investigate if the timing of initiation of invasive mechanical ventilation (IMV) for critically ill patients with COVID-19 is associated with mortality.

MATERIALS AND METHODS

The data for this study were derived from a multicenter cohort study of critically ill adults with COVID-19 admitted to ICUs at 68 hospitals across the US from March 1 to July 1, 2020. We examined the association between early (ICU days 1-2) versus late (ICU days 3-7) initiation of IMV and time-to-death. Patients were followed until the first of hospital discharge, death, or 90 days. We adjusted for confounding using a multivariable Cox model.

RESULTS

Among the 1879 patients included in this analysis (1199 male [63.8%]; median age, 63 [IQR, 53-72] years), 1526 (81.2%) initiated IMV early and 353 (18.8%) initiated IMV late. A total of 644 of the 1526 patients (42.2%) in the early IMV group died, and 180 of the 353 (51.0%) in the late IMV group died (adjusted HR 0.77 [95% CI, 0.65-0.93]).

CONCLUSIONS

In critically ill adults with respiratory failure from COVID-19, early compared to late initiation of IMV is associated with reduced mortality.

Prophylactic noninvasive respiratory support in the immediate postoperative period after cardiac surgery - a systematic review and network meta-analysis

BACKGROUND

Noninvasive respiratory support has been increasingly applied in the immediate postoperative period to prevent postoperative pulmonary complications (PPCs). However, the optimal approach remains uncertain. We sought to evaluate the comparative effectiveness of various noninvasive respiratory strategies used in the immediate postoperative period after cardiac surgery.

METHODS

We conducted a frequentist random-effect network meta-analysis (NMA) of randomized controlled trials (RCTs) comparing the prophylactic use of noninvasive ventilation (NIV), continuous positive airway pressure (CPAP), high flow nasal cannula (HFNC), or postoperative usual care (PUC) in the immediate postoperative period after cardiac surgery. Databases were systematically searched through September 28, 2022. Study selection, data extraction, and quality assessment were performed in duplicate. The primary outcome was the incidence of PPCs.

RESULTS

Sixteen RCTs enrolling 3011 patients were included. Compared with PUC, NIV significantly reduced the incidence of PPCs [relative risk (RR) 0.67, 95% confidence interval (CI): 0.49 to 0.93; absolute risk reduction (ARR) 7.6%, 95% CI: 1.6-11.8%; low certainty] and the incidence of atelectasis (RR 0.65, 95% CI: 0.45 to 0.93; ARR 19.3%, 95% CI: 3.9-30.4%; moderate certainty); however, prophylactic NIV was not associated with a decreased reintubation rate (RR 0.82, 95% CI: 0.29 to 2.34; low certainty) or reduced short-term mortality (RR 0.64, 95% CI: 0.16 to 2.52; very low certainty). As compared to PUC, the preventive use of CPAP (RR 0.85, 95% CI: 0.60 to 1.20; very low certainty) or HFNC (RR 0.74, 95% CI: 0.46 to 1.20; low certainty) had no significant beneficial effect on the incidence of PPCs, despite exhibiting a downward trend. Based on the surface under the cumulative ranking curve, the highest-ranked treatment for reducing the incidence of PPCs was NIV (83.0%), followed by HFNC (62.5%), CPAP (44.3%), and PUC (10.2%).

CONCLUSIONS

Current evidence suggest that the prophylactic use of NIV in the immediate postoperative period is probably the most effective noninvasive respiratory approach to prevent PPCs in patients undergoing cardiac surgery. Given the overall low certainty of the evidence, further high-quality research is warranted to better understand the relative benefits of each noninvasive ventilatory support.

CLINICAL TRIAL REGISTRATION

PROSPERO, https://www.crd.york.ac.uk/prospero/ , registry number: CRD42022303904.

International Survey of High-Flow Nasal Therapy Use for Respiratory Failure in Adult Patients

(1) Background: High-flow nasal therapy (HFNT) has shown several benefits in addressing respiratory failure. However, the quality of evidence and the guidance for safe practice are lacking. This survey aimed to understand HFNT practice and the needs of the clinical community to support safe practice. (2) Method: A survey questionnaire was developed and distributed to relevant healthcare professionals through national networks in the UK, USA and Canada; responses were collected between October 2020 and April 2021. (3) Results: In the UK and Canada, HFNT was used in 95% of hospitals, with the highest use being in the emergency department. HNFT was widely used outside of a critical care setting. HFNT was mostly used to treat acute type 1 respiratory failure (98%), followed by acute type 2 respiratory failure and chronic respiratory failure. Guideline development was felt to be important (96%) and urgent (81%). Auditing of practice was lacking in 71% of hospitals. In the USA, HFNT was broadly similar to UK and Canadian practice. (4) Conclusions: The survey results reveal several key points: (a) HFNT is used in clinical conditions with limited evidence; (b) there is a lack of auditing; (c) it is used in wards that may not have the appropriate skill mix; and (d) there is a lack of guidance for HFNT use.

High flow nasal oxygen (HFNO) in the treatment of COVID-19 infection of adult patients from - An emergency perspective: A systematic review and meta-analysis

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by SARS-CoV-2, which was first discovered in Wuhan, China. The disease has grown into a global pandemic causing mild to moderate symptoms in most people. The disease can also exhibit serious illnesses, especially for patients with other chronic diseases such as cardiovascular diseases, diabetes, chronic respiratory disease, or cancer. In such cases of severe illness, high flow nasal oxygen (HFNO) has been used to provide oxygenation to COVID-19 patients. However, the efficiency of HFNO remains uncertain, prompting the conduction of this systematic review to evaluate the effectiveness of the therapy. A thorough search for relevant and original articles was carried out on five electronic databases, including ScienceDirect, PubMed, Cochrane Library, Embase, and Google Scholar. No time limitation was placed during the search as it included all the articles related to COVID-19 from 2019 to 2022. The search strategy utilized in this systematic review yielded 504 articles, of which only 10 met the eligibility criteria and were included. Our meta-analysis reveals that HFNO success rate was higher than HFNO failure rates (0.52 (95% CI; 0.47, 0.56) and 0.48 (95% CI; 0.44, 0.53), respectively), however, the difference was statistically insignificant. HFNO was associated with a significant decrease in mortality and intubation rates (0.28 (95% CI; 0.19, 0.39) and 0.28 (95% CI; 0.18, 0.41), respectively). Our statistical analysis has shown that significantly lower ROX index (5.07 ± 1.66, p = 0.028) and PaO2/FiO2 (100 ± 27.51, p = 0.031) are associated with HFNO failure, while a significantly lower respiratory rate (RR) (23.17 ± 4.167, p = 0.006) is associated with HFNO success. No statistically significant difference was observed in SpO2/FiO2 ratio between the HFNO success and failure groups (154.23 ± 42.74 vs. 124.025 ± 28.50, p = 0.62, respectively). Based on the results from our meta-analysis, the success or failure of HFNO in treating COVID-19 adult patients remains uncertain. However, HFNO has been shown to be an effective treatment in reducing mortality and intubation rates. Therefore, HFNO can be recommended for COVID-19 patients but with close monitoring and should be carried out by experienced healthcare workers.

The COVID-19 Driving Force: How It Shaped the Evidence of Non-Invasive Respiratory Support

During the COVID-19 pandemic, the use of non-invasive respiratory support (NIRS) became crucial in treating patients with acute hypoxemic respiratory failure. Despite the fear of viral aerosolization, non-invasive respiratory support has gained attention as a way to alleviate ICU overcrowding and reduce the risks associated with intubation. The COVID-19 pandemic has led to an unprecedented increased demand for research, resulting in numerous publications on observational studies, clinical trials, reviews, and meta-analyses in the past three years. This comprehensive narrative overview describes the physiological rationale, pre-COVID-19 evidence, and results of observational studies and randomized control trials regarding the use of high-flow nasal oxygen, non-invasive mechanical ventilation, and continuous positive airway pressure in adult patients with COVID-19 and associated acute hypoxemic respiratory failure. The review also highlights the significance of guidelines and recommendations provided by international societies and the need for further well-designed research to determine the optimal use of NIRS in treating this population.

Utility and timing of the respiratory rate-oxygenation index in the prediction of high-flow oxygen therapy failure in acute hypoxemic respiratory failure of infective etiology: a prospective observational study

During and following the COVID-19 pandemic, the world has witnessed a surge in high-flow oxygen therapy (HFOT) use. The ability to provide high oxygenation levels with remarkable comfort levels has been the grounds for the same. Despite the advantages, delays in intubation leading to poor overall outcomes have been noticed in subgroups of patients on HFOT. The respiratory rate-oxygenation (ROX) index has been proposed to be a useful indicator to predict HFOT success. In this study, we have examined the utility of the ROX index prospectively in cases of acute hypoxemic respiratory failure (AHRF) due to infective etiologies. A total of 70 participants were screened, and 55 were recruited for the study. The majority of participants were males (56.4%), with diabetes mellitus being the most common comorbidity (29.1%). The mean age of the study subjects was 46.27±15.6 years. COVID-19 (70.9%) was the most common etiology for AHRF, followed by scrub typhus (21.8%). 19 (34.5%) experienced HFOT failure, and 9 (16.4%) subjects died during the study period. Demographic characteristics did not differ between either of the two groups (HFOT success versus failure and survived group versus expired group). The ROX index was significantly different between the HFOT success versus failure group at baseline, 2, 4, 6, 12, and 24 hours. The best cut-offs of the ROX index at baseline and 2 hours were 4.4 (sensitivity 91.7%, specificity 86.7%) and 4.3 (sensitivity 94.4% and specificity 86.7%), respectively. The ROX index was found to be an efficient tool in predicting HFOT failure in cases of AHRF with infective etiology.