The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

Lung microbiota composition, respiratory mechanics, and outcomes in COVID-19-related ARDS

Few data are available on the lung microbiota composition of patients with coronavirus disease 2019-related acute respiratory distress syndrome (C-ARDS) receiving invasive mechanical ventilation (IMV). Moreover, it has never been investigated whether there is a potential correlation between lung microbiota communities and respiratory mechanics. We performed a prospective observational study in two intensive care units of a university hospital in Italy. Lung microbiota was investigated by bacterial 16S rRNA gene sequencing, performed on bronchoalveolar lavage fluid samples withdrawn after intubation. The lung bacterial communities were analyzed after stratification by respiratory system compliance/predicted body weight (Crs) and ventilatory ratio (VR). Weaning from IMV and hospital survival were assessed as secondary outcomes. In 70 C-ARDS patients requiring IMV from 1 April through 31 December 2020, the lung microbiota composition (phylum taxonomic level, permutational multivariate analysis of variance test) significantly differed between who had low Crs vs those with high Crs (P = 0.010), as well as in patients with low VR vs high VR (P = 0.012). As difference-driving taxa, Proteobacteria (P = 0.017) were more dominant and Firmicutes (P = 0.040) were less dominant in low- vs high-Crs patients. Similarly, Proteobacteria were more dominant in low- vs high-VR patients (P = 0.013). After multivariable regression analysis, we further observed lung microbiota diversity as a negative predictor of weaning from IMV and hospital survival (hazard ratio = 3.31; 95% confidence interval, 1.52-7.20, P = 0.048). C-ARDS patients with low Crs/low VR had a Proteobacteria-dominated lung microbiota. Whether patients with a more diverse lung bacterial community may have more chances to be weaned from IMV and discharged alive from the hospital warrants further large-scale investigations.

IMPORTANCE

Lung microbiota characteristics were demonstrated to predict ventilator-free days and weaning from mechanical ventilation in patients with acute respiratory distress syndrome (ARDS). In this study, we observed that in severe coronavirus disease 2019 patients with ARDS who require invasive mechanical ventilation, lung microbiota characteristics were associated with respiratory mechanics. Specifically, the lung microbiota of patients with low respiratory system compliance and low ventilatory ratio was characterized by Proteobacteria dominance. Moreover, after multivariable regression analysis, we also found an association between patients' microbiota diversity and a higher possibility of being weaned from mechanical ventilation and discharged alive from the hospital. For these reasons, lung microbiota characterization may help to stratify patient characteristics and orient the delivery of target interventions. (This study has been registered at ClinicalTrials.gov on 17 February 2020 under identifier NCT04271345.).

Registered at ClinicalTrials.gov, 17 February 2020 (NCT0427135).

Hypercapnia and its relationship with respiratory infections

INTRODUCTION

Hypercapnia is developed in patients with acute and/or chronic respiratory conditions. Clinical data concerning hypercapnia and respiratory infections interaction is limited.

AREAS COVERED

Currently, the relationship between hypercapnia and respiratory infections remains unclear. In this review, we summarize studies on the effects of hypercapnia on models of pulmonary infections to clarify the role of elevated CO2 in these pulmonary pathologies. Hypercapnia affects different cell types in the alveoli, leading to changes in the immune response. In vitro studies show that hypercapnia downregulates the NF-κβ pathway, reduces inflammation and impairs epithelial wound healing. While in vivo models show a dual role between short- and long-term effects of hypercapnia on lung infection. However, it is still controversial whether the effects observed under hypercapnia are pH dependent or not.

EXPERT OPINION

The role of hypercapnia is still a controversial debate. Hypercapnia could play a beneficial role in mechanically ventilated models, by lowering the inflammation produced by the stretch condition. But it could be detrimental in infectious scenarios, causing phagocyte dysfunction and lack of infection control. Further data concerning hypercapnia on respiratory infections is needed to elucidate this interaction.

Physiologic Markers of Disease Severity in ARDS

Despite its significant limitations, the PaO2 /FIO2 remains the standard tool to classify disease severity in ARDS. Treatment decisions and research enrollment have depended on this parameter for over 50 years. In addition, several variables have been studied over the past few decades, incorporating other physiologic considerations such as ventilation efficiency, lung mechanics, and right-ventricular performance. This review describes the strengths and limitations of all relevant parameters, with the goal of helping us better understand disease severity and possible future treatment targets.

Association between ventilatory ratio and mortality in patients with acute respiratory distress syndrome and COVID 19: A multicenter, retrospective cohort study

BACKGROUND

Mortality rates in patients with COVID-19 undergoing mechanical ventilation in the intensive care unit are high. The causes of this mortality have been rigorously investigated. The aim of the present study is to establish mortality risk factors related to lung mechanics measured at days 1 and 5 in patients with covid-19 ARDS managed with invasive mechanical ventilation in the intensive care unit.

METHODS

A retrospective observational multicenter study including consecutive patients with a confirmed diagnosis of COVID-19-induced ARDS, admitted to three institutions and seven intensive care units in the city of Bogota between May 20, 2020 and May 30, 2022 who required mechanical ventilation for at least five days. Data were collected from the medical records of patients who met the inclusion criteria on day 1 and day 5 of mechanical ventilation. The primary outcome assessed was mortality at day 30.

RESULTS

A total of 533 consecutive patients admitted with ARDS with COVID-19 were included. Ventilatory ratio, plateau pressure and driving pressure measured on day 5 were significantly higher in non-survivors (p < 0.05). Overall, 30-day follow-up mortality was 48.8%. The increases between day 1 and day 5 in the ventilatory ratio (OR 1.42, 95%CI 1.03-2.01, p = 0.04), driving pressure (OR 1.56, 95%CI 1.10-2.22, p = 0.01); and finally plateau pressure (OR 1.9, 95%CI 1.34-2.69, p = 0.001) were associated with an increased risk of death. There was no association between deterioration of PaO2/FIO2 index and mortality (OR 1.34, 95%CI 0.96-1.56, p = 0.053).

CONCLUSIONS

Ventilatory ratio, plateau pressure, driving pressure, and age were identified as independent risk factors for 30-day mortality in patients with ARDS due to COVID-19 on day 5 of invasive mechanical ventilation.

Dead-Space Ventilation Indices and Mortality in Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis

OBJECTIVES

Acute respiratory distress syndrome (ARDS) is associated with high ventilation-perfusion heterogeneity and dead-space ventilation. However, whether the degree of dead-space ventilation is associated with outcomes is uncertain. In this systematic review and meta-analysis, we evaluated the ability of dead-space ventilation measures to predict mortality in patients with ARDS.

DATA SOURCES

MEDLINE, CENTRAL, and Google Scholar from inception to November 2022.

STUDY SELECTION

Studies including adults with ARDS reporting a dead-space ventilation index and mortality.

DATA EXTRACTION

Two reviewers independently identified eligible studies and extracted data. We calculated pooled effect estimates using a random effects model for both adjusted and unadjusted results. The quality and strength of evidence were assessed using the Quality in Prognostic Studies and Grading of Recommendations, Assessment, Development, and Evaluation, respectively.

DATA SYNTHESIS

We included 28 studies in our review, 21 of which were included in our meta-analysis. All studies had a low risk of bias. A high pulmonary dead-space fraction was associated with increased mortality (odds ratio [OR], 3.52; 95% CI, 2.22-5.58; p < 0.001; I2 = 84%). After adjusting for other confounding variables, every 0.05 increase in pulmonary-dead space fraction was associated with an increased odds of death (OR, 1.23; 95% CI, 1.13-1.34; p < 0.001; I2 = 57%). A high ventilatory ratio was also associated with increased mortality (OR, 1.55; 95% CI, 1.33-1.80; p < 0.001; I2 = 48%). This association was independent of common confounding variables (OR, 1.33; 95% CI, 1.12-1.58; p = 0.001; I2 = 66%).

CONCLUSIONS

Dead-space ventilation indices were independently associated with mortality in adults with ARDS. These indices could be incorporated into clinical trials and used to identify patients who could benefit from early institution of adjunctive therapies. The cut-offs identified in this study should be prospectively validated.

Risk factors associated with mortality among elderly patients with COVID-19: Data from 55 intensive care units in Spain

INTRODUCTION AND OBJECTIVES

Critically-ill elderly ICU patients with COVID-19 have poor outcomes. We aimed to compare the rates of in-hospital mortality between non-elderly and elderly critically-ill COVID-19 ventilated patients, as well as to analyze the characteristics, secondary outcomes and independent risk factors associated with in-hospital mortality of elderly ventilated patients.

PATIENTS AND METHODS

We conducted a multicentre, observational cohort study including consecutive critically-ill patients admitted to 55 Spanish ICUs due to severe COVID-19 requiring mechanical ventilation (non-invasive respiratory support [NIRS; include non-invasive mechanical ventilation and high-flow nasal cannula] and invasive mechanical ventilation [IMV]) between February 2020 and October 2021.

RESULTS

Out of 5,090 critically-ill ventilated patients, 1,525 (27%) were aged ≥70 years (554 [36%] received NIRS and 971 [64%] received IMV. In the elderly group, median age was 74 years (interquartile range 72-77) and 68% were male. Overall in-hospital mortality was 31% (23% in patients <70 years and 50% in those ≥70 years; p<0.001). In-hospital mortality in the group ≥70 years significantly varied according to the modality of ventilation (40% in NIRS vs. 55% in IMV group; p<0.001). Factors independently associated with in-hospital mortality in elderly ventilated patients were age (sHR 1.07 [95%CI 1.05-1.10], p<0.001); previous admission within the last 30 days (sHR 1.40 [95%CI 1.04-1.89], p = 0.027); chronic heart disease (sHR 1.21 [95%CI 1.01-1.44], p = 0.041); chronic renal failure (sHR 1.43 [95%CI 1.12- 1.82], p = 0.005); platelet count (sHR 0.98 [95% CI 0.98-0.99], p<0.001); IMV at ICU admission (sHR 1.41 [95% CI 1.16- 1.73], p<0.001); and systemic steroids (sHR 0.61 [95%CI 0.48- 0.77], p<0.001).

CONCLUSIONS

Amongst critically-ill COVID-19 ventilated patients, those aged ≥70 years presented significantly higher rates of in-hospital mortality than younger patients. Increasing age, previous admission within the last 30 days, chronic heart disease, chronic renal failure, platelet count, IMV at ICU admission and systemic steroids (protective) all comprised independent factors for in-hospital mortality in elderly patients.

A blood microRNA classifier for the prediction of ICU mortality in COVID-19 patients: a multicenter validation study

BACKGROUND

The identification of critically ill COVID-19 patients at risk of fatal outcomes remains a challenge. Here, we first validated candidate microRNAs (miRNAs) as biomarkers for clinical decision-making in critically ill patients. Second, we constructed a blood miRNA classifier for the early prediction of adverse outcomes in the ICU.

METHODS

This was a multicenter, observational and retrospective/prospective study including 503 critically ill patients admitted to the ICU from 19 hospitals. qPCR assays were performed in plasma samples collected within the first 48 h upon admission. A 16-miRNA panel was designed based on recently published data from our group.

RESULTS

Nine miRNAs were validated as biomarkers of all-cause in-ICU mortality in the independent cohort of critically ill patients (FDR < 0.05). Cox regression analysis revealed that low expression levels of eight miRNAs were associated with a higher risk of death (HR from 1.56 to 2.61). LASSO regression for variable selection was used to construct a miRNA classifier. A 4-blood miRNA signature composed of miR-16-5p, miR-192-5p, miR-323a-3p and miR-451a predicts the risk of all-cause in-ICU mortality (HR 2.5). Kaplan‒Meier analysis confirmed these findings. The miRNA signature provides a significant increase in the prognostic capacity of conventional scores, APACHE-II (C-index 0.71, DeLong test p-value 0.055) and SOFA (C-index 0.67, DeLong test p-value 0.001), and a risk model based on clinical predictors (C-index 0.74, DeLong test-p-value 0.035). For 28-day and 90-day mortality, the classifier also improved the prognostic value of APACHE-II, SOFA and the clinical model. The association between the classifier and mortality persisted even after multivariable adjustment. The functional analysis reported biological pathways involved in SARS-CoV infection and inflammatory, fibrotic and transcriptional pathways.

CONCLUSIONS

A blood miRNA classifier improves the early prediction of fatal outcomes in critically ill COVID-19 patients.

Ventilatory ratio as a predictor for extubation failure in critical ill patients based on MIMIC-IV database (from 2008 to 2019)

Background: The predictive ability of the ventilatory ratio (VR) for extubation failure risk in critically ill patients on mechanical ventilation is unclear. This study aims to examine the predictive ability of VR for extubation failure risk. Methods: This retrospective study was based on the MIMIC-IV database. The MIMIC-IV database consists of the clinical information of patients who were admitted to the intensive care unit at the Beth Israel Deaconess Medical Center between 2008 and 2019. With extubation failure as the primary outcome and in-hospital mortality as the secondary outcome, we assessed the predictive value of VR 4 hours before extubation using a multivariate logistic regression model. Results: Of 3,569 ventilated patients who were included, the rate of extubation-failure was 12.7% and the median Sequential Organ Failure Assessment (SOFA) score was 6 before extubation. Increased VR, elevated heart rate, greater positive end-expiratory pressure, higher blood urea nitrogen level, higher platelet count, greater SOFA score, decreased pH, decreased tidal volume, presence of chronic pulmonary disease, paraplegia, and metastatic solid tumor were independent predictors for extubation failure. A threshold of 1.595 of VR was associated with prolonged intensive care unit length of stay, higher risk of mortality and extubation failure. The area under the receiver operating characteristic curve (ROC) for VR was 0.669 [0.635-0.703], which was significantly larger than the rapid shallow breathing index [0.510 (0.476-0.545)] and the partial pressure of oxygen to the fraction of inspired oxygen [0.586 (0.551-0.621)]. Conclusion: VR 4 hours before extubation was associated with extubation failure, mortality, and prolonged length of stay in the intensive care unit. VR provides good predictive performance for extubation failure (measured by ROC) than the rapid shallow breathing index. Further prospective studies are warranted to confirm these findings.

Dead space ventilation-related indices: bedside tools to evaluate the ventilation and perfusion relationship in patients with acute respiratory distress syndrome

Cumulative evidence has demonstrated that the ventilatory ratio closely correlates with mortality in acute respiratory distress syndrome (ARDS), and a primary feature in coronavirus disease 2019 (COVID-19)-ARDS is increased dead space that has been reported recently. Thus, new attention has been given to this group of dead space ventilation-related indices, such as physiological dead space fraction, ventilatory ratio, and end-tidal-to-arterial PCO₂ ratio, which, albeit distinctive, are all global indices with which to assess the relationship between ventilation and perfusion. These parameters have already been applied to positive end expiratory pressure titration, prediction of responses to the prone position and the field of extracorporeal life support for patients suffering from ARDS. Dead space ventilation-related indices remain hampered by several deflects; notwithstanding, for this catastrophic syndrome, they may facilitate better stratifications and identifications of subphenotypes, thereby providing therapy tailored to individual needs.

Ventilatory ratio and mechanical power in prolonged mechanically ventilated COVID-19 patients versus respiratory failures of other etiologies

BACKGROUND

Evidence suggests differences in ventilation efficiency and respiratory mechanics between early COVID-19 pneumonia and classical acute respiratory distress syndrome (ARDS), as measured by established ventilatory indexes, such as the ventilatory ratio (VR; a surrogate of the pulmonary dead-space fraction) or mechanical power (MP; affected, e.g., by changes in lung-thorax compliance).

OBJECTIVES

The aim of this study was to evaluate VR and MP in the late stages of the disease when patients are ready to be liberated from the ventilator after recovering from COVID-19 pneumonia compared to respiratory failures of other etiologies.

DESIGN

A retrospective observational cohort study of 249 prolonged mechanically ventilated, tracheotomized patients with and without COVID-19-related respiratory failure.

METHODS

We analyzed each group's VR and MP distributions and trajectories [repeated-measures analysis of variance (ANOVA)] during weaning. Secondary outcomes included weaning failure rates between groups and the ability of VR and MP to predict weaning outcomes (using logistic regression models).

RESULTS

The analysis compared 53 COVID-19 cases with a heterogeneous group of 196 non-COVID-19 subjects. VR and MP decreased across both groups during weaning. COVID-19 patients demonstrated higher values for both indexes throughout weaning: median VR 1.54 versus 1.27 (p < 0.01) and MP 26.0 versus 21.3 Joule/min (p < 0.01) at the start of weaning, and median VR 1.38 versus 1.24 (p < 0.01) and MP 24.2 versus 20.1 Joule/min (p < 0.01) at weaning completion. According to the multivariable analysis, VR was not independently associated with weaning outcomes, and the ability of MP to predict weaning failure or success varied with lung-thorax compliance, with COVID-19 patients demonstrating consistently higher dynamic compliance along with significantly fewer weaning failures (9% versus 30%, p < 0.01).

CONCLUSION

COVID-19 patients differed considerably in ventilation efficiency and respiratory mechanics among prolonged ventilated individuals, demonstrating significantly higher VRs and MP. The differences in MP were linked with higher lung-thorax compliance in COVID-19 patients, possibly contributing to the lower rate of weaning failures observed.

Respiratory system mechanics, gas exchange, and outcomes in mechanically ventilated patients with COVID-19-related acute respiratory distress syndrome: a systematic review and meta-analysis

The association of respiratory mechanics, particularly respiratory system static compliance (C_RS), with severity of hypoxaemia in patients with COVID-19-related acute respiratory distress syndrome (ARDS) has been widely debated, with some studies reporting distinct ARDS phenotypes based on C_RS. Ascertaining whether such phenotypes exist is important, because they might indicate the need for ventilation strategies that differ from those used in patients with ARDS due to other causes. In a systematic review and meta-analysis of studies published between Dec 1, 2019, and March 14, 2022, we evaluated respiratory system mechanics, ventilator parameters, gas exchange parameters, and clinical outcomes in patients with COVID-19-related ARDS. Among 11 356 patients in 37 studies, mean reported C_RS, measured close to the time of endotracheal intubation, was 35·8 mL/cm H₂O (95% CI 33·9-37·8; I²=96·9%, τ²=32·6). Pooled mean C_RS was normally distributed. Increasing ARDS severity (assessed by PaO₂/FiO₂ ratio as mild, moderate, or severe) was associated with decreasing C_RS. We found no evidence for distinct C_RS-based clinical phenotypes in patients with COVID-19-related ARDS, and we therefore conclude that no change in conventional lung-protective ventilation strategies is warranted. Future studies should explore the personalisation of mechanical ventilation strategies according to factors including respiratory system mechanics and haemodynamic status in patients with ARDS.

Physiological response to prone positioning in intubated adults with COVID-19 acute respiratory distress syndrome: a retrospective study

Background

COVID-19 related acute respiratory distress syndrome (ARDS) has specific characteristics compared to ARDS in other populations. Proning is recommended by analogy with other forms of ARDS, but few data are available regarding its physiological effects in this population. This study aimed to assess the effects of proning on oxygenation parameters (PaO2/FiO2 and alveolo-arterial gradient (Aa-gradient)), blood gas analysis, ventilatory ratio (VR), respiratory system compliance (CRS) and estimated dead space fraction (VD/VT HB). We also looked for variables associated with treatment failure.

Methods

Retrospective monocentric study of intubated COVID-19 ARDS patients managed with an early intubation, low to moderate positive end-expiratory pressure and early proning strategy hospitalized from March 6 to April 30 2020. Blood gas analysis, PaO2/FiO2, Aa-gradient, VR, CRS and VD/VT HB were compared before and at the end of each proning session with paired t-tests or Wilcoxon tests (p < 0.05 considered as significant). Proportions were assessed using Fischer exact test or Chi square test.

Results

Forty-two patients were included for a total of 191 proning sessions, median duration of 16 (5–36) hours. Considering all sessions, PaO2/FiO2 increased (180 [148–210] vs 107 [90–129] mmHg, p < 0.001) and Aa-gradient decreased (127 [92–176] vs 275 [211–334] mmHg, p < 0.001) with proning. CRS (36.2 [30.0–41.8] vs 32.2 [27.5–40.9] ml/cmH2O, p = 0.003), VR (2.4 [2.0–2.9] vs 2.3 [1.9–2.8], p = 0.028) and VD/VT HB (0.72 [0.67–0.76] vs 0.71 [0.65–0.76], p = 0.022) slightly increased. Considering the first proning session, PaO2/FiO2 increased (186 [165–215] vs 104 [94–126] mmHg, p < 0.001) and Aa-gradient decreased (121 [89–160] vs 276 [238–321] mmHg, p < 0.001), while CRS, VR and VD/VT HB were unchanged. Similar variations were observed during the subsequent proning sessions. Among the patients who experienced treatment failure (defined as ICU death or need for extracorporeal membrane oxygenation), fewer expressed a positive response in terms of oxygenation (defined as increase of more than 20% in PaO2/FiO2) to the first proning (67 vs 97%, p = 0.020).

Conclusion

Proning in COVID-19 ARDS intubated patients led to an increase in PaO2/FiO2 and a decrease in Aa-gradient if we consider all the sessions together, the first one or the 4 subsequent sessions independently. When considering all sessions, CRS increased and VR and VD/VT HB only slightly increased.

Ventilatory settings in the initial 72 h and their association with outcome in out-of-hospital cardiac arrest patients: a preplanned secondary analysis of the targeted hypothermia versus targeted normothermia after out-of-hospital cardiac arrest (TTM2) trial

PURPOSE

The optimal ventilatory settings in patients after cardiac arrest and their association with outcome remain unclear. The aim of this study was to describe the ventilatory settings applied in the first 72 h of mechanical ventilation in patients after out-of-hospital cardiac arrest and their association with 6-month outcomes.

METHODS

Preplanned sub-analysis of the Target Temperature Management-2 trial. Clinical outcomes were mortality and functional status (assessed by the Modified Rankin Scale) 6 months after randomization.

RESULTS

A total of 1848 patients were included (mean age 64 [Standard Deviation, SD = 14] years). At 6 months, 950 (51%) patients were alive and 898 (49%) were dead. Median tidal volume (V_T) was 7 (Interquartile range, IQR = 6.2-8.5) mL per Predicted Body Weight (PBW), positive end expiratory pressure (PEEP) was 7 (IQR = 5-9) cmH₂0, plateau pressure was 20 cmH₂0 (IQR = 17-23), driving pressure was 12 cmH₂0 (IQR = 10-15), mechanical power 16.2 J/min (IQR = 12.1-21.8), ventilatory ratio was 1.27 (IQR = 1.04-1.6), and respiratory rate was 17 breaths/minute (IQR = 14-20). Median partial pressure of oxygen was 87 mmHg (IQR = 75-105), and partial pressure of carbon dioxide was 40.5 mmHg (IQR = 36-45.7). Respiratory rate, driving pressure, and mechanical power were independently associated with 6-month mortality (omnibus p-values for their non-linear trajectories: p < 0.0001, p = 0.026, and p = 0.029, respectively). Respiratory rate and driving pressure were also independently associated with poor neurological outcome (odds ratio, OR = 1.035, 95% confidence interval, CI = 1.003-1.068, p = 0.030, and OR = 1.005, 95% CI = 1.001-1.036, p = 0.048). A composite formula calculated as [(4*driving pressure) + respiratory rate] was independently associated with mortality and poor neurological outcome.

CONCLUSIONS

Protective ventilation strategies are commonly applied in patients after cardiac arrest. Ventilator settings in the first 72 h after hospital admission, in particular driving pressure and respiratory rate, may influence 6-month outcomes.

Major candidate variables to guide personalised treatment with steroids in critically ill patients with COVID-19: CIBERESUCICOVID study

Purpose

Although there is evidence supporting the benefits of corticosteroids in patients affected with severe coronavirus disease 2019 (COVID-19), there is little information related to their potential benefits or harm in some subgroups of patients admitted to the intensive care unit (ICU) with COVID-19. We aim to investigate to find candidate variables to guide personalized treatment with steroids in critically ill patients with COVID-19.

Methods

Multicentre, observational cohort study including consecutive COVID-19 patients admitted to 55 Spanish ICUs. The primary outcome was 90-day mortality. Subsequent analyses in clinically relevant subgroups by age, ICU baseline illness severity, organ damage, laboratory findings and mechanical ventilation were performed. High doses of corticosteroids (≥ 12 mg/day equivalent dexamethasone dose), early administration of corticosteroid treatment (< 7 days since symptom onset) and long term of corticosteroids (≥ 10 days) were also investigated.

Results

Between February 2020 and October 2021, 4226 patients were included. Of these, 3592 (85%) patients had received systemic corticosteroids during hospitalisation. In the propensity-adjusted multivariable analysis, the use of corticosteroids was protective for 90-day mortality in the overall population (HR 0.77 [0.65–0.92], p = 0.003) and in-hospital mortality (SHR 0.70 [0.58–0.84], p < 0.001). Significant effect modification was found after adjustment for covariates using propensity score for age (p = 0.001 interaction term), Sequential Organ Failure Assessment (SOFA) score (p = 0.014 interaction term), and mechanical ventilation (p = 0.001 interaction term). We observed a beneficial effect of corticosteroids on 90-day mortality in various patient subgroups, including those patients aged ≥ 60 years; those with higher baseline severity; and those receiving invasive mechanical ventilation at ICU admission. Early administration was associated with a higher risk of 90-day mortality in the overall population (HR 1.32 [1.14–1.53], p < 0.001). Long-term use was associated with a lower risk of 90-day mortality in the overall population (HR 0.71 [0.61–0.82], p < 0.001). No effect was found regarding the dosage of corticosteroids. Moreover, the use of corticosteroids was associated with an increased risk of nosocomial bacterial pneumonia and hyperglycaemia.

Conclusion

Corticosteroid in ICU-admitted patients with COVID-19 may be administered based on age, severity, baseline inflammation, and invasive mechanical ventilation. Early administration since symptom onset may prove harmful.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00134-022-06726-w.

Monitoring Lung Injury Severity and Ventilation Intensity during Mechanical Ventilation

Acute respiratory distress syndrome (ARDS) is a severe form of respiratory failure burden by high hospital mortality. No specific pharmacologic treatment is currently available and its ventilatory management is a key strategy to allow reparative and regenerative lung tissue processes. Unfortunately, a poor management of mechanical ventilation can induce ventilation induced lung injury (VILI) caused by physical and biological forces which are at play. Different parameters have been described over the years to assess lung injury severity and facilitate optimization of mechanical ventilation. Indices of lung injury severity include variables related to gas exchange abnormalities, ventilatory setting and respiratory mechanics, ventilation intensity, and the presence of lung hyperinflation versus derecruitment. Recently, specific indexes have been proposed to quantify the stress and the strain released over time using more comprehensive algorithms of calculation such as the mechanical power, and the interaction between driving pressure (DP) and respiratory rate (RR) in the novel DP multiplied by four plus RR [(4 × DP) + RR] index. These new parameters introduce the concept of ventilation intensity as contributing factor of VILI. Ventilation intensity should be taken into account to optimize protective mechanical ventilation strategies, with the aim to reduce intensity to the lowest level required to maintain gas exchange to reduce the potential for VILI. This is further gaining relevance in the current era of phenotyping and enrichment strategies in ARDS.

Anticoagulant Treatment in Severe ARDS COVID-19 Patients

Patients with COVID-19 may complicate their evolution with thromboembolic events. Incidence of thromboembolic complications are high and also, patients with the critically-ill disease showed evidence of microthrombi and microangiopathy in the lung probably due to endothelial damage by directly and indirectly injured endothelial and epithelial cells. Pulmonary embolism, deep venous thrombosis and arterial embolism were reported in patients with COVID-19, and several analytical abnormal coagulation parameters have been described as well. D-dimer, longer coagulation times and lower platelet counts have been associated with poor outcomes. The use of anticoagulation or high doses of prophylactic heparin is controversial. Despite the use of anticoagulation or high prophylactic dose of heparin have been associated with better outcomes in observational studies, only in patients with non-critically ill disease benefits for anticoagulation was observed. In critically-ill patient, anticoagulation was not associated with better outcomes. Other measures such as antiplatelet therapy, fibrinolytic therapy or nebulized anticoagulants are being studied in ongoing clinical trials.

Early prolonged prone position in noninvasively ventilated patients with SARS-CoV-2-related moderate-to-severe hypoxemic respiratory failure: clinical outcomes and mechanisms for treatment response in the PRO-NIV study

Background

Whether prone position (PP) improves clinical outcomes in COVID-19 pneumonia treated with noninvasive ventilation (NIV) is unknown. We evaluated the effect of early PP on 28-day NIV failure, intubation and death in noninvasively ventilated patients with moderate-to-severe acute hypoxemic respiratory failure due to COVID-19 pneumonia and explored physiological mechanisms underlying treatment response.

Methods

In this controlled non-randomized trial, 81 consecutive prospectively enrolled patients with COVID-19 pneumonia and moderate-to-severe (paO2/FiO2 ratio < 200) acute hypoxemic respiratory failure treated with early PP + NIV during Dec 2020–May 2021were compared with 162 consecutive patients with COVID-19 pneumonia matched for age, mortality risk, severity of illness and paO2/FiO2 ratio at admission, treated with conventional (supine) NIV during Apr 2020–Dec 2020 at HUMANITAS Gradenigo Subintensive Care Unit, after propensity score adjustment for multiple baseline and treatment-related variables to limit confounding. Lung ultrasonography (LUS) was performed at baseline and at day 5. Ventilatory parameters, physiological dead space indices (DSIs) and circulating inflammatory and procoagulative biomarkers were monitored during the initial 7 days.

Results

In the intention-to-treat analysis. NIV failure occurred in 14 (17%) of PP patients versus 70 (43%) of controls [HR = 0.32, 95% CI 0.21–0.50; p < 0.0001]; intubation in 8 (11%) of PP patients versus 44 (30%) of controls [HR = 0.31, 95% CI 0.18–0.55; p = 0.0012], death in 10 (12%) of PP patients versus 59 (36%) of controls [HR = 0.27, 95% CI 0.17–0.44; p < 0.0001]. The effect remained significant within different categories of severity of hypoxemia (paO2/FiO2 < 100 or paO2/FiO2 100–199 at admission). Adverse events were rare and evenly distributed. Compared with controls, PP therapy was associated with improved oxygenation and DSIs, reduced global LUS severity indices largely through enhanced reaeration of dorso-lateral lung regions, and an earlier decline in inflammatory markers and D-dimer. In multivariate analysis, day 1 CO2 response outperformed O2 response as a predictor of LUS changes, NIV failure, intubation and death.

Conclusion

Early prolonged PP is safe and is associated with lower NIV failure, intubation and death rates in noninvasively ventilated patients with COVID-19-related moderate-to-severe hypoxemic respiratory failure. Early dead space reduction and reaeration of dorso-lateral lung regions predicted clinical outcomes in our study population.

Clinical trial registration

ISRCTN23016116. Retrospectively registered on May 1, 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-03937-x.

Methodology of a Large Multicenter Observational Study of Patients with COVID-19 in Spanish Intensive Care Units

INTRODUCTION

The COVID-19 pandemic created tremendous challenges for health-care systems. Intensive care units (ICU) were hit with a large volume of patients requiring ICU admission, mechanical ventilation, and other organ support with very high mortality. The Centro de Investigación Biomédica en Red-Enfermedades Respiratorias (CIBERES), a network of Spanish researchers to investigate in respiratory disease, commissioned the current proposal in response to the Instituto de Salud Carlos III (ISCIII) call.

METHODS

CIBERESUCICOVID is a multicenter, observational, prospective/retrospective cohort study of patients with COVID-19 admitted to Spanish ICUs. Several work packages were created, including study population and ICU data collection, follow-up, biomarkers and miRNAs, data management and quality.

RESULTS

This study included 6102 consecutive patients admitted to 55 ICUs homogeneously distributed throughout Spain and the collection of blood samples from more than 1000 patients. We enrolled a large population of COVID-19 ICU-admitted patients including baseline characteristics, ICU and MV data, treatments complications, and outcomes. The in-hospital mortality was 31%, and 76% of patients required invasive mechanical ventilation. A 3-6 month and 1 year follow-up was performed. Few deaths after 1 year discharge were registered. Low anti-SARS-CoV-2 S antibody levels predict mortality in critical COVID-19. These antibodies contribute to prevent systemic dissemination of SARS-CoV-2. The severity of COVID-19 impacts the circulating miRNA profile. Plasma miRNA profiling emerges as a useful tool for risk-based patient stratification in critically ill COVID-19 patients.

CONCLUSIONS

We present the methodology used in a large multicenter study sponsored by ISCIII to determine the short- and long-term outcomes in patients with COVID-19 admitted to more than 50 Spanish ICUs.