Factors Associated With Prolonged Ventilation in Patients Receiving Prone Positioning Protocol With Muscle Relaxants for Severe COVID-19 Pneumonia

BACKGROUND

Prone positioning and neuromuscular blocking agents (NMBAs) are frequently used to treat severe respiratory failure from COVID-19 pneumonia. Prone positioning has shown to improve mortality, whereas NMBAs are used to prevent ventilator asynchrony and reduce patient self-inflicted lung injury. However, despite the use of lung-protective strategies, high death rates in this patient population have been reported.

METHODS

We retrospectively examined the factors affecting prolonged mechanical ventilation in patients receiving prone positioning plus muscle relaxants. The medical records of 170 patients were reviewed. Subjects were divided into 2 groups according to ventilator-free days (VFDs) at day 28. Whereas subjects with VFDs < 18 d were defined as prolonged mechanical ventilation, subjects with VFDs ≥18 d were defined as short-term mechanical ventilation. Subjects' baseline status, status at ICU admission, therapy before ICU admission, and treatment in the ICU were studied.

RESULTS

Under the proning protocol for COVID-19, the mortality rate in our facility was 11.2%. The prognosis may be improved by avoiding lung injury in the early stages of mechanical ventilation. According to multifactorial logistic regression analysis, persistent SARS-CoV-2 viral shedding in blood (P = .027), higher daily corticosteroid use before ICU admission (P = .007), delayed recovery of lymphocyte count (P < .001), and higher maximal fibrinogen degradation products (P = .039) were associated with prolonged mechanical ventilation. A significant relationship was found between daily corticosteroid use before admission and VFDs by squared regression analysis (y = -0.00008522x² + 0.01338x + 12.8; x: daily corticosteroids dosage before admission [prednisolone mg/d]; y: VFDs/28 d, R² = 0.047, P = .02). The peak point of the regression curve was 13.4 d at 78.5 mg/d of the equivalent prednisolone dose, which corresponded to the longest VFDs.

CONCLUSIONS

Persistent SARS-CoV-2 viral shedding in blood, high corticosteroid dose from the onset of symptoms to ICU admission, slow recovery of lymphocyte counts, and high levels of fibrinogen degradation products after admission were associated with prolonged mechanical ventilation in subjects with severe COVID-19 pneumonia.

Randomized controlled trial of ultra-protective vs. protective ventilation strategy in veno-arterial extracorporeal membrane oxygenation patients with refractory cardiogenic shock: a study protocol for the ultra-ECMO trial

Background

A protective or ultra-protective tidal volume strategy is widely applied to patients with acute respiratory distress syndrome (ARDS). The use of very low tidal volume has the potential to further redece ventilation-induced lung injury (VILI) comparde with a "normal" lung protective management. Plus, cardiogenic pulmonary edema (CPE) caused by hydrostatic mechanisms in patients with cardiogenic shock has similar respiratory mechanics to those found in patients with ARDS. And no consensus exists on mechanical ventilation parameter settings in patients with VA-ECMO. The study aimed to investigate the impact of an ultra-protective tidal volume strategy on the 28-day ventilator-free day (VFD) number in VA-ECMO-supported patients with refractory cardiogenic shock, including cardiac arrest.

Methods

The Ultra-ECMO trial is a randomized controlled, open-label, single-center prospective superiority trial. At the onset of ECMO initiation, we will divide patients randomly into an intervention group and a control group in a 1:1 ratio. The control group will adopt protective ventilation settings [initial tidal volume: 6 ml/kg of predicted body weight (PBW)] for ventilation, and the intervention group will adopt ultra-protective ventilation settings (initial tidal volume: 4 ml/kg of PBW) for ventilation. The procedure is expected to last 72 h, after which the ventilator settings will be at the intensivists' discretion. The primary outcome is the VFD number at 28 days after inclusion. The secondary outcomes will include respiratory mechanics; analgesic/sedation dosage; lung ultrasound score; interleukin-6, interleukin-8, and monocyte chemotactic protein-1 levels in broncho-alveolar lavage fluid at the moment of enrollment (T0), 24, 48, and 72 h (T1, T2, and T3, respectively) after ECMO initiation; total time (in days) required for ECMO weaning; length of stay in the intensive care unit; total cost of hospitalization; amounts of resuscitative fluids; and in-hospital mortality.

Discussion

VA-ECMO-treated patients without ARDS possess abnormal lung function. CPE, thoracic compliance reduction, and poor pulmonary blood perfusion are frequently present, and these patients can more easily progress to ARDS. It seems that targeting the protective tidal volume can lower adverse outcome incidence rates, even in patients without ARDS. This trial seeks to answer the question of whether adopting an ultra-protective tidal volume strategy can lead to superior primary and secondary outcomes compared to adopting a protective tidal volume strategy in patients treated by VA-ECMO. The Ultra-ECMO trial will provide an innovative mechanical ventilation strategy for VA-ECMO-supported patients for improving treatment outcomes at biological and potentially clinical levels.

Clinical Trial Registration

ChiCTR2200067118.

Effect of Tocilizumab on "Ventilator Free Days" Composite Outcome in SARS-CoV-2 Patients: A Retrospective Competing Risk Analysis

Background

SARS-CoV-2 infection demonstrates a wide range of severity. More severe cases demonstrate a cytokine storm with elevated serum interleukin-6, hence IL-6 receptor antibody tocilizumab was tried for the management of severe cases.

Aims

Effect of tocilizumab on ventilator-free days among critically ill SARS-CoV-2 patients.

Method

Retrospective propensity score matching study, comparing mechanically ventilated patients who received tocilizumab to a control group.

Results

29 patients in the intervention group were compared to 29 controls. Matched groups were similar. Ventilator-free days were more numerous in the intervention group (SHR 2.7, 95% CI: 1.2 - 6.3; p = 0.02), ICU mortality rate was not different (37.9% versus 62%, p = 0.1), actual ventilator-free periods were significantly longer in tocilizumab group (mean difference 4.7 days; p = 0.02). Sensitivity analysis showed a significantly lower hazard ratio of death in tocilizumab group (HR 0.49, 95% CI: 0.25 - 0.97; p = 0.04). There was no difference in positive cultures among groups (55.2% in tocilizumab group versus 34.5% in the control; p = 0.1).

Conclusion

Tocilizumab may improve the composite outcome of ventilator-free days at day 28 among mechanically ventilated SARS-CoV-2 patients; it is associated with significantly longer actual ventilator-free periods, and insignificantly lower mortality and higher superinfection.

Timing and Clinical Significance of Fluid Overload in Pediatric Acute Respiratory Distress Syndrome

OBJECTIVES

Fluid overload is associated with worse outcomes in adult and pediatric acute respiratory distress syndrome. However, the time-course of fluid overload and its relationship to outcome has not been described. We aimed to determine the relationship between the timing of fluid overload and outcomes over the first 7 days after acute respiratory distress syndrome onset in children.

DESIGN

Retrospective cohort study.

SETTING

Single tertiary care PICU.

PATIENTS

Intubated children with acute respiratory distress syndrome between 2011 and 2019.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Daily and cumulative total fluid intake, total output, urine output, and fluid balance were collected for each 24-hour period from days 1 to 7 after acute respiratory distress syndrome onset. We tested the association between daily cumulative fluid metrics with PICU mortality and probability of extubation by 28 days using multivariable logistic and competing risk regression, respectively. In a subset of children, plasma was collected on day 1 and day 3 of acute respiratory distress syndrome and angiopoietin-2 quantified. Of 723 children with acute respiratory distress syndrome, 132 died (18%). In unadjusted analysis, nonsurvivors had higher cumulative fluid balance starting on day 3. In multivariable analysis, a positive cumulative fluid balance on days 5 through 7 was associated with increased mortality. Higher cumulative fluid balance on days 4 to 7 was associated with lower probability of extubation. Elevated angiopoietin-2 on day 1 predicted early (within 3 d) fluid overload greater than or equal to 10%, and elevated angiopoietin-2 on day 3 predicted late (between days 4 and 7) fluid overload.

CONCLUSIONS

Fluid overload after day 4 of acute respiratory distress syndrome, but not before, was associated with worse outcomes. Higher angiopoietin-2 predicted subsequent fluid overload. Our results suggest that future interventions aimed at managing fluid overload may have differential efficacy depending on when in the time-course of acute respiratory distress syndrome they are initiated.

Effects of Methylprednisolone on Ventilator-Free Days in Mechanically Ventilated Patients with Acute Respiratory Distress Syndrome and COVID-19: A Retrospective Study

Objectives: There are limited data regarding the efficacy of methylprednisolone in patients with acute respiratory distress syndrome (ARDS) due to coronavirus disease 2019 (COVID-19) requiring invasive mechanical ventilation. We aimed to determine whether methylprednisolone is associated with increases in the number of ventilator-free days (VFDs) among these patients. Design: Retrospective single-center study. Setting: Intensive care unit. Patients: All patients with ARDS due to confirmed SARS-CoV-2 infection and requiring invasive mechanical ventilation between 1 March and 29 May 2020 were included. Interventions: None. Measurements and Main Results: The primary outcome was ventilator-free days (VFDs) for the first 28 days. Defined as being alive and free from mechanical ventilation. The primary outcome was analyzed with competing-risks regression based on Fine and Gray's proportional sub hazards model. Death before day 28 was considered to be the competing event. A total of 77 patients met the inclusion criteria. Thirty-two patients (41.6%) received methylprednisolone. The median dose was 1 mg·kg^-1 (IQR: 1-1.3 mg·kg^-1) and median duration for 5 days (IQR: 5-7 days). Patients who received methylprednisolone had a mean 18.8 VFDs (95% CI, 16.6-20.9) during the first 28 days vs. 14.2 VFDs (95% CI, 12.6-16.7) in patients who did not receive methylprednisolone (difference, 4.61, 95% CI, 1.10-8.12, p = 0.001). In the multivariable competing-risks regression analysis and after adjusting for potential confounders (ventilator settings, prone position, organ failure support, severity of the disease, tocilizumab, and inflammatory markers), methylprednisolone was independently associated with a higher number of VFDs (subhazards ratio: 0.10, 95% CI: 0.02-0.45, p = 0.003). Hospital mortality did not differ between the two groups (31.2% vs. 28.9%, p = 0.82). Hospital length of stay was significantly shorter in the methylprednisolone group (24 days [IQR: 15-41 days] vs. 37 days [IQR: 23-52 days], p = 0.046). The incidence of positive blood cultures was higher in patients who received methylprednisolone (37.5% vs. 17.8%, p = 0.052). However, 81% of patients who received methylprednisolone also received tocilizumab. The number of days with hyperglycemia was similar in the two groups. Conclusions: Methylprednisolone was independently associated with increased VFDs and shortened hospital length of stay. The combination of methylprednisolone and tocilizumab was associated with a higher rate of positive blood cultures. Further trials are needed to evaluate the benefits and safety of methylprednisolone in moderate or severe COVID-19 ARDS.

PRactice of VENTilation in Patients with Novel Coronavirus Disease (PRoVENT-COVID): rationale and protocol for a national multicenter observational study in The Netherlands

Background

The coronavirus disease 2019 (COVID-19) pandemic is rapidly expanding across the world, with more than 100,000 new cases each day as of end-June 2020. Healthcare workers are struggling to provide the best care for COVID-19 patients. Approaches for invasive ventilation vary widely between and within countries and new insights are acquired rapidly. We aim to investigate invasive ventilation practices and outcome in COVID-19 patients in the Netherlands.

Methods

PRoVENT-COVID (‘study of PRactice of VENTilation in COVID-19’) is an investigator-initiated national, multicenter observational study to be undertaken in intensive care units (ICUs) in The Netherlands. Consecutive COVID-19 patients aged 18 years or older, who are receiving invasive ventilation in the participating ICUs, are to be enrolled during a 10-week period, with a daily follow-up of 7 days. The primary outcome is ventilatory management (including tidal volume expressed as mL/kg predicted body weight and positive end-expiratory pressure expressed as cmH₂O) during the first 3 days of ventilation. Secondary outcomes include other ventilatory variables, use of rescue therapies for refractory hypoxemia such as prone positioning and extracorporeal membrane oxygenation, use of sedatives, vasopressors and inotropes; daily cumulative fluid balances; acute kidney injury; ventilator-free days and alive at day 28 (VFD-28), duration of ICU and hospital stay, and ICU, hospital and 90-day mortality.

Discussion

PRoVENT-COVID will be the largest observational study to date, with high density ventilatory data and major outcomes. There is urgent need for a better understanding of ventilation practices, and the effects of ventilator settings on outcomes in COVID-19 patients. The results of PRoVENT-COVID will be rapidly disseminated through electronic presentations, such as webinars and electronic conferences, and publications in international peer-reviewed journals. Access to source data will be made available through local, regional and national anonymized datasets on request, and after agreement of the PRoVENT-COVID steering committee.

Trial Registration

PRoVENT-COVID is registered at clinicaltrials.gov (identifier NCT04346342).

Low Free T3 Is Associated With Worse Outcomes in Patients in the ICU Requiring Invasive Mechanical Ventilation

OBJECTIVE

Critical illness causes a decrease in serum free triiodothyronine (T₃) levels. This condition, known as nonthyroidal illness syndrome (NTIS), is associated with poor outcomes. The association of NTIS and outcomes in patients in the intensive care unit (ICU) requiring mechanical ventilation has not been well studied. This study aimed to determine the impact of NTIS on the outcomes of these patients.

METHODS

This prospective study included 162 patients in the ICU who underwent mechanical ventilation. Serum free T₃ levels were tested on the day of initiation of mechanical ventilation. The rates of in-hospital mortality and ventilator-free days (VFDs) at day 28 after the initiation of mechanical ventilation were compared between patients with low (<2.3 pg/mL) and normal (≥2.3 pg/mL) free T₃ levels. Patients who died while on mechanical ventilation were assigned a VFD of 0.

RESULTS

Low T₃ was present in 60% of study patients. The in-hospital mortality rate of the entire cohort was 39%, and the mean and median VFDs at day 28 were 13.5 and 21 days, respectively. Compared to patients with normal free T₃, patients with low free T₃ had higher in-hospital mortality (52% vs 19%, P < .001) and less mean and median VFDs at day 28 (10.7 vs 18 and 0 vs 23, respectively. P < .001 for both mean and median VFDs).

CONCLUSIONS

The presence of low T₃ due to NTIS in patients in the ICU requiring mechanical ventilation is associated with poor outcomes.

Reappraisal of Ventilator-Free Days in Critical Care Research

Ventilator-free days (VFDs) are a commonly reported composite outcome measure in acute respiratory distress syndrome trials. VFDs combine survival and duration of ventilation in a manner that summarizes the "net effect" of an intervention on these two outcomes. However, this combining of outcome measures makes VFDs difficult to understand and analyze, which contributes to imprecise interpretations. We discuss the strengths and limitations of VFDs and other "failure-free day" composites, and we provide a framework for when and how to use these outcome measures. We also provide a comprehensive discussion of the different analytic methods for analyzing and interpreting VFDs, including Student's t tests and rank-sum tests, as well as competing risk regressions treating extubation as the primary outcome and death as the competing risk. Using simulations, we illustrate how the statistical test with optimal power depends on the relative contributions of mortality and ventilator duration on the composite effect size. Finally, we recommend a simple analysis and reporting framework using the competing risk approach, which provides clear information on the effect size of an intervention, a statistical test and measure of confidence with the ability to adjust for baseline factors and allow interim monitoring for trials. We emphasize that any approach to analyzing a composite outcome, including other "failure-free day" constructs, should also be accompanied by an examination of the components.

Argument against the Routine Use of Steroids for Pediatric Acute Respiratory Distress Syndrome

Steroids have a plausible mechanism of action of reducing severity of lung disease in acute respiratory distress syndrome (ARDS) but have failed to show consistent benefits in patient-centered outcomes. Many studies have confounding from the likely presence of ventilator-induced lung injury and steroids may have shown benefit because administration minimized ongoing inflammation incited by injurious ventilator settings. If steroids have benefit, it is likely for specific populations that fall within the heterogeneous diagnosis of ARDS. Those pediatric patients with concurrent active asthma or reactive airway disease of prematurity, in addition to ARDS, are the most common group likely to derive benefit from steroids, but are poorly studied. With the information currently available, it does not appear that the typical adult or pediatric patient with ARDS derives benefit from steroids and steroids should not be given on a routine basis.

Efficacy of High-Flow Nasal Cannula Therapy in Acute Hypoxemic Respiratory Failure: Decreased Use of Mechanical Ventilation

BACKGROUND

We evaluated the efficacy of high-flow nasal cannula (HFNC) therapy, a promising respiratory support method for acute hypoxemic respiratory failure (AHRF).

METHODS

We conducted a retrospective single-center cohort study comparing the periods before (June 2010 to May 2012) and after (June 2012 to May 2014) HFNC introduction (pre- and post-HFNC periods). During these periods, we retrieved cases of AHRF treated with any respiratory support (invasive ventilation, noninvasive ventilation [NIV], and HFNC) and compared in-hospital mortality, ICU/intermediate care unit/hospital stay, and need for mechanical ventilation.

RESULTS

Eighty-three subjects (65 treated with NIV, and 18 treated with invasive ventilation) and 89 subjects (33 treated with HFNC, 43 treated with NIV, and 13 treated with invasive ventilation) identified from 782 pre-HFNC and 930 post-HFNC records of acute respiratory failure who required emergent admissions to the respiratory care department were analyzed. Overall, the in-hospital mortality rate was similar, although there was a non-significant and slight decrease from 35 to 27% (P = .26). There was no significant difference among ICU, intermediate care unit (P = .80), and hospital (P = .33) stay. In the post-HFNC period, significantly fewer subjects required mechanical ventilation (NIV or invasive ventilation) (100% vs 63%, P < .01). Additionally, there were significantly fewer ventilator days (median [interquartile range] of 5 [2-11] vs 2 [1-5] d, P < .05) and more ventilator-free days (median [interquartile range] of 18 [0-25] vs 26 [20-27] d, P < .01).

CONCLUSIONS

HFNC might be an alternative for AHRF subjects with NIV intolerance.

Usefulness of a selective neutrophil elastase inhibitor, sivelestat, in acute lung injury patients with sepsis

BACKGROUND

Neutrophil elastase plays a crucial role in the development of acute lung injury (ALI) in patients with systemic inflammatory response syndrome (SIRS). The clinical efficacy of the neutrophil elastase inhibitor, sivelestat, for patients with ALI associated with SIRS has not been convincingly demonstrated. The aim of this study was to determine if there are clinical features of patients with this condition that affect the efficacy of sivelestat.

METHODS

This was a retrospective study of 110 ALI patients with SIRS. Clinical information, including the etiology of ALI, the number of organs failing, scoring systems for assessing the severity of illness, and laboratory data, was collected at the time of diagnosis. Information on the number of ventilator-free days (VFDs) and changes in PaO(2)/F(I)O(2) (ΔP/F) before and 7 days after the time of ALI diagnosis was also collected. The effect of sivelestat on ALI patients was also examined based on whether they had sepsis and whether their initial serum procalcitonin level was ≥0.5 ng/mL.

RESULTS

There were 70 patients who were treated with sivelestat and 40 control patients. VFDs and ΔP/F were significantly higher in the treated patients than in the control patients. However, there was no significant difference in the patient survival rate between the two groups. Sivelestat was more effective in ALI patients with a PaO(2)/F(I)O(2) ratio ≥ 140 mmHg or sepsis. Sivelestat significantly prolonged survival and led to higher VFDs and increased ΔP/F in septic patients and patients with initial serum procalcitonin levels ≥ 0.5 ng/mL.

CONCLUSION

The results may facilitate a future randomized controlled trial to determine whether sivelestat is beneficial for ALI patients with sepsis.