The effect of prone positioning on mortality in patients with acute respiratory distress syndrome: a meta-analysis of randomized controlled trials

The effect of swimmer position during prone ventilation on the onset of brachial plexus injury in the intensive care unit: A multiprofessional clinical study protocol

BACKGROUND

Prone positioning improves oxygenation in adults with acute respiratory distress syndrome (ARDS) and has been extensively applied in intensive care units (ICU) during the COVID-19 pandemic. Although some complications due to the manoeuvre are well known, brachial plexus injury after prone positioning is reported as a rare complication and the phenomenon could be either very rare or underestimated.

AIM

This study aimed to evaluate the effect of swimmer position during prone ventilation on the onset of brachial plexus injury in patients admitted to ICU for ARDS. The study will also evaluate the safety of prolonged prone positioning collecting data on any adverse events occurred.

STUDY DESIGN

A prospective, observational cohort study will be conducted in a tertiary level ICU in the metropolitan area of Milano (Italy) specialized in advanced treatment of patients with ARDS. This observational study will report clinical data on the electromyography (EMG) and the muscle strength assessment, including comorbidities and cardio-respiratory status. A baseline EMG will be performed within 2 h from the first pronation manoeuvre and immediately at the end of each pronation cycle. The functional assessment of patients will be also performed at the end of ICU stay and at hospital discharge.

RESULTS

The primary outcome is to estimate the prevalence of brachial plexus injury in patients with ARDS placed in the swimmer position during prone ventilation. Secondary outcomes will also include the safety of the manoeuvre by evaluation of all adverse events classified as skin or ocular damage, loss of tube and vascular access and new pressure ulcers.

RELEVANCE TO CLINICAL PRACTICE

The findings of this study will contribute to understand the possible benefits/harms of prone ventilation performed using swimmer position. Eventually, this will call for the development of specific and tailored rehabilitation programs for patients with upper limb injuries during ICU stay, including also timely follow-up upon ICU-discharge.

Prone position for acute respiratory distress syndrome and the hazards of meta-analysis

BACKGROUND

Researchers have tried unsuccessfully for many years using randomized controlled trials to show the efficacy of prone ventilation in treating ARDS. These failed attempts were of use in designing the successful PROSEVA trial, published in 2013. However, the evidence provided by meta-analyses in support of prone ventilation for ARDS was too low to be conclusive. The present study shows that meta-analysis is indeed not the best approach for the assessment of evidence as to the efficacy of prone ventilation.

METHODS

We performed a cumulative meta-analysis to prove that only the PROSEVA trial, due to its strong protective effect, has substantially impacted on the outcome. We also replicated nine published meta-analyses including the PROSEVA trial. We performed leave-one-out analyses, removing one trial at a time from each meta-analysis, measuring p values for effect size, and also the Cochran's Q test for heterogeneity assessment. We represented these analyses in a scatter plot to identify outlier studies influencing heterogeneity or overall effect size. We used interaction tests to formally identify and evaluate differences with the PROSEVA trial.

RESULTS

The positive effect of the PROSEVA trial accounted for most of the heterogeneity and for the reduction of overall effect size in the meta-analyses. The interaction tests we conducted on the nine meta-analyses formally confirmed the difference in the effectiveness of prone ventilation between the PROSEVA trial the other studies.

CONCLUSIONS

The clinical lack of homogeneity between the PROSEVA trial design and the other studies should have discouraged the use of meta-analysis. Statistical considerations support this hypothesis, suggesting that the PROSEVA trial is an independent source of evidence.

Prolonged vs shorter awake prone positioning for COVID-19 patients with acute respiratory failure: a multicenter, randomised controlled trial

PURPOSE

Awake prone positioning has been reported to reduce endotracheal intubation in patients with coronavirus disease 2019 (COVID-19)-related acute hypoxemic respiratory failure (AHRF). However, it is still unclear whether using the awake prone positioning for longer periods can further improve outcomes.

METHODS

In this randomized, open-label clinical trial conducted at 12 hospitals in China, non-intubated patients with COVID-19-related AHRF were randomly assigned to prolonged awake prone positioning (target > 12 h daily for 7 days) or standard care with a shorter period of awake prone positioning. The primary outcome was endotracheal intubation within 28 days after randomization. The key secondary outcomes included mortality and adverse events.

RESULTS

In total, 409 patients were enrolled and randomly assigned to prolonged awake prone positioning (n = 205) or standard care (n = 204). In the first 7 days after randomization, the median duration of prone positioning was 12 h/d (interquartile range [IQR] 12-14 h/d) in the prolonged awake prone positioning group vs. 5 h/d (IQR 2-8 h/d) in the standard care group. In the intention-to-treat analysis, intubation occurred in 35 (17%) patients assigned to prolonged awake prone positioning and in 56 (27%) patients assigned to standard care (relative risk 0.62 [95% confidence interval (CI) 0.42-0.9]). The hazard ratio (HR) for intubation was 0.56 (0.37-0.86), and for mortality was 0.63 (0.42-0.96) for prolonged awake prone positioning versus standard care, within 28 days. The incidence of pre-specified adverse events was low and similar in both groups.

CONCLUSION

Prolonged awake prone positioning of patients with COVID-19-related AHRF reduces the intubation rate without significant harm. These results support prolonged awake prone positioning of patients with COVID-19-related AHRF.

Effect of prone positioning on survival in adult patients receiving venovenous extracorporeal membrane oxygenation for acute respiratory distress syndrome: a prospective multicenter randomized controlled study

Background

Current data supporting the use of prone positioning (PP) during venovenous extracorporeal membrane oxygenation (VV-ECMO) in patients with acute respiratory distress syndrome (ARDS) are limited. This prospective randomized controlled study aimed to determine whether PP implemented within 24 hours of ECMO can improve survival in these patients.

Methods

From June 2021 to July 2023, 97 adult patients receiving VV-ECMO for ARDS in three centers were enrolled and 1:1 randomized into PP (n=49) and control groups (n=48). Patients in the PP group receiving prone positioning, while the control group were maintained in the supine position. The primary outcome was 30-day survival, and secondary outcomes included in-hospital survival and other clinical outcomes.

Results

All 97 patients were included for analysis. Patient characteristics did not significantly differ between the two groups. The median duration of PP was 81 hours, and the median number of PP sessions was 5 times. PP improved oxygenation and ventilator parameters. The incidence of complications during PP was low, with pressure sores being the most frequent (10.2%). The 30-day survival was significantly higher in the PP group (67.3% vs. 45.8%; P=0.033), as was in-hospital survival (61.2% vs. 39.6%; P=0.033). In the PP group, the successful ECMO weaning rate was significantly higher (77.5% vs. 50.0%; P=0.005), and the duration of ECMO support was significantly shorter {10 [8-11] vs. 10 [8-14] days; P=0.038}. However, in subgroup analysis of COVID patients the 30-day survival, in-hospital survival, successful ECMO weaning rate and the duration of ECMO support did not differ between the groups. The duration of mechanical ventilation, length of intensive care unit stay, and length of hospital stay did not significantly differ between the groups.

Conclusions

When initiated within 24 hours of ECMO, PP can improve 30-day survival in patients with ARDS receiving VV-ECMO. In addition, it may improve the successful ECMO weaning rate and reduce the duration of ECMO support. However, considering the limitations, more strictly designed, large sample prospective randomized controlled trials are proposed.

Trial Registration

Chinese Clinical Trial Registry ChiCTR2300075326.

Awake prone position in COVID-19-related acute respiratory failure: a meta-analysis of randomized controlled trials

BACKGROUND

We aimed to investigate the effects of awake prone positioning (APP) in nonintubated adult patients with acute hypoxemic respiratory failure due to COVID-19.

METHODS

The PubMed, Embase, Web of Science and Cochrane Central Register databases were searched up to June 1, 2022. All randomized trials investigating the effects of APP were included in the present meta-analysis. The primary outcome was intubation rate, and the secondary outcomes included the length of intensive care unit (ICU) stay, hospital stay, and mortality. Prescribed subgroup analysis was also conducted.

RESULTS

A total of 10 randomized trials enrolling 2324 patients were ultimately included in the present study. The results indicated that APP was associated with a significant reduction in the intubation rate (OR 0.77, 95% CI 0.63 to 0.93, P = 0.007). However, no differences could be observed in the length of ICU stay or hospitalization or mortality. Subgroup analysis suggested that patients in the ICU settings (OR 0.74, 95% CI 0.60 to 0.91, P = 0.004), patients whose median APP time was more than 4 h (OR 0.77, 95% CI 0.63 to 0.93, P = 0.008), and patients with an average baseline SpO₂ to FiO₂ ratio less than 200 (OR 0.75, 95% CI 0.61 to 0.92) were more likely to benefit from APP, indicated a significantly reduced intubation rate.

CONCLUSION

Based on the current evidence, nonintubated adult patients with hypoxemic respiratory failure due to COVID-19 infection who underwent APP were shown to have a significantly reduced intubation rate. However, no differences in ICU or hospital length of stay or mortality could be observed between APP and usual care.

REGISTRATION NUMBER

CRD42022337846.

Early Prone versus Supine Positioning in Moderate to Severe Coronavirus Disease 2019 Patients with Acute Respiratory Distress Syndrome

Objectives

This study sought to determine whether early prone positioning of patients with moderate to severe COVID-19-related acute respiratory distress syndrome (ARDS) lowers the mortality rate.

Methods

We conducted a retrospective study using data from intensive care units of two tertiary centers in Oman. Adult patients with moderate to severe COVID-19-related ARDS with a PaO2/FiO2 ratio < 150 on FiO2 of 60% or more and a positive end-expiratory pressure of at least 8 cm H2O who were admitted between 1 May 2020 and 31 October 2020 were selected as participants. All patients were intubated and subjected to mechanical ventilation within 48 hours of admission and placed in either prone or supine position. Mortality was measured and compared between the patients from the two groups.

Results

A total of 235 patients were included (120 in the prone group and 115 in the supine group). There were no significant differences in mortality (48.3% vs. 47.8%; p =0.938) and discharge rates (50.8% vs. 51.3%; p =0.942) between the prone and supine groups, respectively.

Conclusions

Early prone positioning of patients with COVID-19-related ARDS does not result in a significant reduction in mortality.

COVID-19 Lessons Learned: Prone Positioning With and Without Invasive Ventilation

Prone positioning (PP) has been used extensively for patients requiring invasive mechanical ventilation for hypoxemic respiratory failure during the COVID-19 pandemic. Evidence suggests that PP was beneficial during the pandemic, as it improves oxygenation and might improve chances of survival, especially in those with a continuum of positive oxygenation responses to the procedure. Additionally, the pandemic drove innovation regarding PP, as it brought attention to awake PP (APP) and the value of an interdisciplinary team approach to PP during a pandemic. APP appears to be safe and effective at improving oxygenation; APP may also reduce the need for intubation in patients requiring advanced respiratory support like high-flow nasal cannula or noninvasive ventilation. Teams specifically assembled for PP during a pandemic also appear useful and can provide needed assistance to bedside clinicians in the time of crisis. Complications associated with PP can be mitigated, and a multidisciplinary approach to reduce the incidence of complications is recommended.

Effect of prone positioning on gas exchange according to lung morphology in patients with acute respiratory distress syndrome

BACKGROUND

There are limited data on the clinical effects of prone positioning according to lung morphology. We aimed to determine whether the gas exchange response to prone positioning differs according to lung morphology.

METHODS

This retrospective study included adult patients with moderate-to-severe acute respiratory distress syndrome (ARDS). The lung morphology of ARDS was assessed by chest computed tomography scan and classified as "diffuse" or "focal." The primary outcome was change in partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO2) ratio after the first prone positioning session: first, using the entire cohort, and second, using subgroups of patients with diffuse ARDS matched 2 to 1 with patients with focal ARDS at baseline.

RESULTS

Ninety-five patients were included (focal ARDS group, 23; diffuse ARDS group, 72). Before prone positioning, the focal ARDS group showed worse oxygenation than the diffuse ARDS group (median PaO2/FiO2 ratio, 79.9 mm Hg [interquartile range (IQR)], 67.7-112.6 vs. 104.0 mm Hg [IQR, 77.6-135.7]; P=0.042). During prone positioning, the focal ARDS group showed a greater improvement in the PaO2/FiO2 ratio than the diffuse ARDS group (median, 55.8 mm Hg [IQR, 11.1-109.2] vs. 42.8 mm Hg [IQR, 11.6-83.2]); however, the difference was not significant (P=0.705). Among the PaO2/FiO2-matched cohort, there was no significant difference in change in PaO2/FiO2 ratio after prone positioning between the groups (P=0.904).

CONCLUSIONS

In patients with moderate-to-severe ARDS, changes in PaO2/FiO2 ratio after prone positioning did not differ according to lung morphology. Therefore, prone positioning can be considered as soon as indicated, regardless of ARDS lung morphology.

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.

Cuidados de enfermagem e posição prona: revisão integrativa

Objetivo: explorar, na literatura científica, práticas atuais de cuidado de enfermagem ou intervenções para pacientes com síndrome respiratório agudo grave (SRAG) submetidos à posição prona.     Síntese do conteúdo: revisão integrativa, na qual foram realizadas buscas nas bases de dados PubMed, CINAHL, Scopus, Web of Science e LILACS em setembro de 2020 e janeiro de 2022, sem recorte temporal, por meio da questão deste estudo: “Quais são os cuidados de enfermagem para pacientes com SRAG submetidos à posição prona?”. Foram selecionados 15 artigos, a partir da busca nas bases de dados. Após a leitura, os cuidados encontrados foram categorizados em alinhamento do corpo para a prevenção de lesões neuromusculares, cuidados com equipamentos diversos, cuidados tegumentares e recomendações neurológicas. Conclusões: o enfermeiro deve ter conhecimento sobre as implicações e as complicações de se manter um paciente na posição prona. Tal conhecimento permitirá tomadas de decisões na construção ou no seguimento de protocolos institucionais que contribuam com a prevenção de riscos e resultem em melhores desfechos para o paciente.

Blastomycosis-Induced Acute Respiratory Distress Syndrome

Blastomycosis is a systemic mycosis endemic to the Midwestern and South Central United States. Infection is caused by inhaling spores of Blastomyces dermatitidis (B. dermatitidis) that inhabit soil. Acute respiratory distress syndrome (ARDS) is a rare complication of pulmonary blastomycosis with a significantly high mortality rate. We present a case of blastomycosis associated with severe ARDS treated with traditional prone position ventilation (PPV) and neurally adjusted ventilator assist (NAVA) along with antifungal therapy, steroids, and supportive care in a rural setting with no access to extracorporeal membrane oxygenation (ECMO). This case demonstrates that traditional therapies such as prone position ventilation can help patients with blastomycosis-associated ARDS especially in rural settings where advanced therapies such as ECMO are lacking. The use of NAVA in blastomycosis-associated ARDS needs further research.

Comparison of prone positioning and extracorporeal membrane oxygenation in acute respiratory distress syndrome: A multicenter cohort study and propensity-matched analysis

Background/Purpose

Both prone positioning and extracorporeal membrane oxygenation (ECMO) are used as rescue therapies for severe hypoxemia in patients with acute respiratory distress syndrome (ARDS). This study compared outcomes between patients with severe influenza pneumonia-related ARDS who received prone positioning and those who received ECMO.

Methods

This retrospective cohort study included eight tertiary referral centers in Taiwan. All patients who were diagnosed as having influenza pneumonia-related severe ARDS were enrolled between January and March 2016. We collected their demographic data and prone positioning and ECMO outcomes from medical records.

Results

In total, 263 patients diagnosed as having ARDS were included, and 65 and 53 of them received prone positioning and ECMO, respectively. The baseline PaO₂/FiO₂ ratio, Acute Physiology and Chronic Health Evaluation II score and Sequential Organ Failure Assessment score did not significantly differ between the two groups. The 60-day mortality rate was significantly higher in the ECMO group than in the prone positioning group (60% vs. 28%, p = 0.001). A significantly higher mortality rate was still observed in the ECMO group after propensity score matching (59% vs. 36%, p = 0.033). In the multivariate Cox regression analysis, usage of prone positioning or ECMO was the single independent predictor for 60-day mortality (hazard ratio: 2.177, p = 0.034).

Conclusion

While the patients receiving prone positioning had better outcome, the causality between prone positioning and the prognosis is unknown. However, the current data suggested that patients with influenza-related ARDS may receive prone positioning before ECMO support.

Infection related catheter complications in patients undergoing prone positioning for acute respiratory distress syndrome: an exposed/unexposed study

Background

Prone positioning (PP) is a standard of care for patients with moderate–severe acute respiratory distress syndrome (ARDS). While adverse events associated with PP are well-documented in the literature, research examining the effect of PP on the risk of infectious complications of intravascular catheters is lacking.

Method

All consecutive ARDS patients treated with PP were recruited retrospectively over a two-year period and formed the exposed group. Intensive care unit (ICU) patients during the same period without ARDS for whom PP was not conducted but who had an equivalent disease severity were matched 1:1 to the exposed group based on age, sex, centre, length of ICU stay and SAPS II (unexposed group). Infection-related catheter complications were defined by a composite criterion, including catheter tip colonization or intravascular catheter-related infection.

Results

A total of 101 exposed patients were included in the study. Most had direct ARDS (pneumonia). The median [Q1–Q3] PP session number was 2 [1–4]. These patients were matched with 101 unexposed patients. The mortality rates of the exposed and unexposed groups were 31 and 30%, respectively. The incidence of the composite criterion was 14.2/1000 in the exposed group compared with 8.2/1000 days in the control group (p = 0.09). Multivariate analysis identified PP as a factor related to catheter colonization or infection (p = 0.04).

Conclusion

Our data suggest that PP is associated with a higher risk of CVC infectious complications.

Improved Oxygenation After Prone Positioning May Be a Predictor of Survival in Patients With Acute Respiratory Distress Syndrome

OBJECTIVES

Prone position ventilation improves oxygenation and reduces the mortality of patients with severe acute respiratory distress syndrome. However, there is limited evidence about which patients would gain most survival benefit from prone positioning. Herein, we investigated whether the improvement in oxygenation after prone positioning is associated with survival and aimed to identify patients who will gain most survival benefit from prone positioning in patients with acute respiratory distress syndrome.

DESIGN

A retrospective cohort study.

SETTING

Medical ICU at a tertiary academic hospital between 2014 and 2020.

PATIENTS

Adult patients receiving prone positioning for moderate-to-severe acute respiratory distress syndrome.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The main outcomes were ICU and 28-day mortality. A total of 116 patients receiving prone positioning were included, of whom 45 (38.8%) were ICU survivors. Although there was no difference in PaO2:FIO2 ratio before the first prone session between ICU survivors and nonsurvivors, ICU survivors had a higher PaO2:FIO2 ratio after prone positioning than nonsurvivors, with significant between-group difference (p < 0.001). The area under the receiver operating characteristic curve of the percentage change in the PaO2:FIO2 ratio between the baseline and 8-12 hours after the first prone positioning to predict ICU mortality was 0.87 (95% CI, 0.80-0.94), with an optimal cutoff value of 53.5% (sensitivity, 91.5%; specificity, 73.3%). Prone responders were defined as an increase in PaO2:FIO2 ratio of greater than or equal to 53.5%. In the multivariate Cox regression analysis, prone responders (hazard ratio, 0.11; 95% CI, 0.05-0.25), immunocompromised condition (hazard ratio, 2.15; 95% CI, 1.15-4.03), and Sequential Organ Failure Assessment score (hazard ratio, 1.16; 95% CI, 1.06-1.27) were significantly associated with 28-day mortality.

CONCLUSIONS

The PaO2:FIO2 ratio after the first prone positioning differed significantly between ICU survivors and nonsurvivors. The improvement in oxygenation after the first prone positioning was a significant predictor of survival in patients with moderate-to-severe acute respiratory distress syndrome.

Multivariate Meta-Analysis of the Mortality Effect of Prone Positioning in the Acute Respiratory Distress Syndrome

BACKGROUND

The efficacy of prone positioning (PP) as therapy of the acute respiratory distress syndrome (ARDS) has varied in recent meta-analyses. The efficacy question was reviewed using a cohesive multivariate meta-analysis model incorporating all available common time-point data.

METHODS

Data from a core group of 8 randomized controlled trials (2001-2013) utilized in 8 current meta-analyses (2014-2017) was extracted for common time points. Multivariate meta-analysis and meta-regression models for prone-hours per day, mechanical ventilation tidal-volume and baseline patient PaO₂/FiO₂, considered as continuous and categorical predictors, determined the pooled relative risk (RR) of mortality for prone versus supine positioning.

RESULTS

Mortality RR at 28-30 days, 2-3 months and 6-months was not significant overall (P > 0.05). Meta-regression of categorical predictors indicated significant mortality reduction (P ≤ 0.001) for ≥ 12 prone-hours (versus < 12), lung protective ventilation (versus none) and moderate-severe ARDS (versus all ARDS). Meta-regressions of continuous predictors were also significant (P ≤ 0.021) and yielded treatment inflection points of efficacious therapy for ≥ 12 prone-hours per day, ≤ 8.5 mL/kg tidal volume and ≤ PaO₂/FiO₂ ratio of 130.

CONCLUSIONS

The mortality treatment effect of PP in ARDS, was not demonstrated in the unadjusted meta-analysis model. Moderator effects indicated consistent significant benefit of prone positioning. In the absence of individual patient data, multivariate models provide more decisive conclusions than individual time point analyses.

The Fundamentals of Respiratory Physiology to Manage the COVID-19 Pandemic: An Overview

The growing coronavirus disease (COVID-19) crisis has stressed worldwide healthcare systems probably as never before, requiring a tremendous increase of the capacity of intensive care units to handle the sharp rise of patients in critical situation. Since the dominant respiratory feature of COVID-19 is worsening arterial hypoxemia, eventually leading to acute respiratory distress syndrome (ARDS) promptly needing mechanical ventilation, a systematic recourse to intubation of every hypoxemic patient may be difficult to sustain in such peculiar context and may not be deemed appropriate for all patients. Then, it is essential that caregivers have a solid knowledge of physiological principles to properly interpret arterial oxygenation, to intubate at the satisfactory moment, to adequately manage mechanical ventilation, and, finally, to initiate ventilator weaning, as safely and as expeditiously as possible, in order to make it available for the next patient. Through the expected mechanisms of COVID-19-induced hypoxemia, as well as the notion of silent hypoxemia often evoked in COVID-19 lung injury and its potential parallelism with high altitude pulmonary edema, from the description of hemoglobin oxygen affinity in patients with severe COVID-19 to the interest of the prone positioning in order to treat severe ARDS patients, this review aims to help caregivers from any specialty to handle respiratory support following recent knowledge in the pathophysiology of respiratory SARS-CoV-2 infection.

Intubation rate of patients with hypoxia due to COVID-19 treated with awake proning: A meta-analysis

BACKGROUND

Awake prone positioning (PP), or proning, is used to avoid intubations in hypoxic patients with COVID-19, but because of the disease's novelty and constant evolution of treatment strategies, the efficacy of awake PP is unclear. We conducted a meta-analysis of the literature to assess the intubation rate among patients with COVID-19 requiring oxygen or noninvasive ventilatory support who underwent awake PP.

METHODS

We searched PubMed, Embase, and Scopus databases through August 15, 2020 to identify relevant randomized control trials, observational studies, and case series. We performed random-effects meta-analyses for the primary outcome of intubation rate. We used moderator analysis and meta-regressions to assess sources of heterogeneity. We used the standard and modified Newcastle-Ottawa Scales (NOS) to assess studies' quality.

RESULTS

Our search identified 1043 articles. We included 16 studies from the original search and 2 in-press as of October 2020 in our analysis. All were observational studies. Our analysis included 364 patients; mean age was 56.8 (SD 7.12) years, and 68% were men. The intubation rate was 28% (95% CI 20%-38%, I² = 63%). The mortality rate among patients who underwent awake PP was 14% (95% CI 7.4%-24.4%). Potential sources of heterogeneity were study design and setting (practice and geographic).

CONCLUSIONS

Our study demonstrated an intubation rate of 28% among hypoxic patients with COVID-19 who underwent awake PP. Awake PP in COVID-19 is feasible and practical, and more rigorous research is needed to confirm this promising intervention.

Prone versus Supine Position Ventilation in Adult Patients with Acute Respiratory Distress Syndrome: A Meta-Analysis of Randomized Controlled Trials

The purpose of this meta-analysis was to compare the efficacy and safety of prone versus supine position ventilation for adult acute respiratory distress syndrome (ARDS) patients. The electronic databases of PubMed, Embase, and the Cochrane Library were systematically searched from their inception up to September 2020. The relative risks (RRs) and weighted mean differences (WMDs) with corresponding 95% confidence intervals (CIs) were employed to calculate pooled outcomes using the random-effects models. Twelve randomized controlled trials that had recruited a total of 2264 adults with ARDS were selected for the final meta-analysis. The risk of mortality in patients who received prone position ventilation was 13% lower than for those who received supine ventilation, but this effect was not statistically significant (RR: 0.87; 95% CI: 0.75–1.00; P = 0.055). There were no significant differences between prone and supine position ventilation on the duration of mechanical ventilation (WMD: −0.22; P = 0.883) or ICU stays (WMD: –0.39; P = 0.738). The pooled RRs indicate that patients who received prone position ventilation had increased incidence of pressure scores (RR: 1.23; P = 0.003), displacement of a thoracotomy tube (RR: 3.14; P = 0.047), and endotracheal tube obstruction (RR: 2.45; P = 0.001). The results indicated that prone positioning during ventilation might have a beneficial effect on mortality, though incidence of several adverse events was significantly increased for these patients.

[Physiotherapy and COVID-19. From intensive care unit to home care-An overview of international guidelines]

INTRODUCTION

The new coronavirus disease 2019 (COVID-19) is responsible for a global pandemic and many deaths. This context requires an adaptation of health systems as well as the role of each healthcare professional, including physiotherapists.

STATE OF THE ART

In order to optimize the management of people with COVID-19, many savant societies published guidelines about physiotherapy interventions within the crisis but none offered a global overview from the intensive care unit to home care. Therefore, the aim of this review is to offer an overview of recommended physiotherapy interventions in order to facilitate the management of these patients, whatever the stage of the disease.

PERSPECTIVES

Owing to the emergent character of the COVID-19, actual guidelines will have to be adjusted according to the evolution of the pandemic and the resources of the hospital and liberal sectors, in particular for the long-term follow-up of these patients. Current and future research will aim to assess the effectiveness of physiotherapy interventions for people with COVID-19.

CONCLUSION

The emergence of COVID-19 required a very rapid adaptation of the health system. The role of physiotherapists is justified at every stage of patients care in order to limit the functional consequences of the disease.

Surviving 2019 novel coronavirus pneumonia: A successful critical case report

•

Prone position ventilation therapy should be considered when P/F ratio was still below 150mmHg after intubation in patients of COVID-19.

•

Acute cor pulmonale(ACP) was often complicated with ARDS caused by COVID-19, dobutamine and the prone position ventilation therapy would be effective.

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High-Flow nasal cannula(HFNC) oxygen therapy could be as sequential strategy to reduce the risk of reintubation and postextubation respiratory failure, and was safe enough during the current COVID-19 outbreak.

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Cardiorespiratory function support therapy was the core of surviving COVID-19, and it was better to start early to achieve good prognosis.

Background

. An outbreak of acute respiratory illness was proved to be infected by a novel coronavirus, officially named Coronavirus Disease 2019 (COVID-19) from World Health Organization (WHO), was confirmed first in Wuhan, China, and has become endemic worldwide, which was a serious threaten to public health all over the world. Herein, we reported a successful critical case of COVID-19 and shared our experience of treatment, which would do a favor for other COVID-19 patients.

Case summary

. A 65-year-old man, Wuhan citizen, was infected by COVID-19, and his pulmonary lesions progressed quickly in five days. On admission to Tongji Hospital, Wuhan, China, the immediate arterial blood gas(ABG) analysis showed the PaO2/FiO2(P/F) ratio was 134.4mmHg, moderate acute respiratory distress syndrome(ARDS) was diagnosed. Emergency tracheal intubation was performed, and the initial ventilator mode and parameters were set up based on the lung-protective ventilation strategy, but the P/F ratio could not be improved, and then the prone position ventilation was carried out for four consecutive days, as long as 16 hours every day, the P/F ratio rose to 180mmHg approximately, which still did not reach to the standard of extubation. And then we found that it was complicated with acute cor pulmonale(ACP) by ultrasound examination, dobutamine and diuretic were used for the treatment of ACP caused by ARDS successfully, and the P/F ratio went up to about 250mmHg. Seven days later after admission, the endotracheal intubation was successfully removed, after extubation, High-Flow nasal cannula(HFNC) oxygen therapy was used as a sequential strategy to prevent reintubation. Ultimately, he was discharged on day 34 after admission.

Conclusion

. Our case presented the treatment process of a critical COVID-19. Effective therapy was crucial to heal COVID-19, and organ function support therapy, especially the cardiorespiratory function support therapy, was the core of treatment.

Validation of neuromuscular blocking agent use in acute respiratory distress syndrome: a meta-analysis of randomized trials

BACKGROUND

We aimed to synthesize up-to-date trials to validate the effects of neuromuscular blocking agent (NMBA) use in patients with moderate-to-severe acute respiratory distress syndrome (ARDS).

METHODS

Several databases including PubMed, EMBASE, Web of Science, and Cochrane Central Register were searched up to November 14, 2019. All randomized trials investigating the use of NMBAs in patients with moderate-to-severe ARDS and reporting mortality data were included in the meta-analysis. The primary outcome was mortality, and the secondary outcomes were clinical outcomes, including respiratory physiological parameters, incidence of barotrauma, ICU-free days, and ventilation-free days.

RESULTS

A total of 7 trials enrolling 1598 patients were finally included in this meta-analysis. The results revealed that the use of NMBAs in moderate-to-severe ARDS could significantly decrease the mortality truncated to day 28 (RR 0.74, 95% CI 0.56 to 0.98, P = 0.03) and day 90 (RR 0.77, 95% CI 0.60 to 0.99, P = 0.04). NMBA use could significantly decrease the incidence of barotrauma (RR 0.56, 95% CI 0.36 to 0.87, P = 0.009). No significant difference was observed in ICU-free days or ventilation-free days between the NMBA and control groups.

CONCLUSION

The use of NMBAs could significantly decrease mortality in moderate-to-severe ARDS patients and decrease the incidence of barotrauma during mechanical ventilation. However, more large-scale randomized trials are needed to further validate the effect of NMBA use in ARDS.

Management of hypoxaemia in the critically ill patient

Hypoxaemia is a common presentation in critically ill patients, with the potential for severe harm if not addressed appropriately. This review provides a framework to guide the management of any hypoxaemic patient, regardless of the clinical setting. Key steps in managing such patients include ascertaining the severity of hypoxaemia, the underlying diagnosis and implementing the most appropriate treatment. Oxygen therapy can be delivered by variable or fixed rate devices, and non-invasive ventilation; if patients deteriorate they may require tracheal intubation and mechanical ventilation. Early critical care team involvement is a key part of this pathway. Specialist treatments for severe hypoxaemia can only be undertaken on an intensive care unit and this field is developing rapidly as trial results become available. It is important that each new scenario is approached in a structured manner with an open diagnostic mind and a clear escalation plan.

Risk Stratification Using Oxygenation in the First 24 Hours of Pediatric Acute Respiratory Distress Syndrome

OBJECTIVE

Oxygenation measured 24 hours after acute respiratory distress syndrome onset more accurately stratifies risk, relative to oxygenation at onset, in both children and adults. However, waiting 24 hours is problematic, especially for interventions that are more efficacious early in the disease course. We aimed to delineate whether oxygenation measured at timepoints earlier than 24 hours would retain predictive validity in pediatric acute respiratory distress syndrome.

DESIGN

Observational cohort study.

SETTING

Two large, academic PICUs.

PATIENTS

Invasively ventilated children with acute respiratory distress syndrome.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

PaO2/FIO2 and oxygenation index (mean airway pressure × FIO2 × 100)/PaO2) were measured at acute respiratory distress syndrome onset, at 6, 12, 18, and 24 hours after in 459 children at the Children's Hospital of Philadelphia. Neither PaO2/FIO2 nor oxygenation index at acute respiratory distress syndrome onset discriminated outcome. Between 6 and 24 hours, both PaO2/FIO2 (area under receiver operating curve for mortality between 0.57 and 0.62; p = 0.049-0.002) and oxygenation index (area under receiver operating curve, 0.60-0.62; p = 0.006-0.001) showed good discrimination and calibration across multiple outcomes, including mortality, ventilator-free days at 28 days, ventilator days in survivors, and probability of extubation, given competing risk of death. The utility of oxygenation at 12 hours was confirmed in an independent cohort from the Children's Hospital of Los Angeles.

CONCLUSION

Oxygenation measured between 6 and 12 hours of acute respiratory distress syndrome onset accurately stratified outcomes in children. Our results have critical implications for the design of trials, especially for interventions with greater impact in early acute respiratory distress syndrome.

Guidelines on the management of acute respiratory distress syndrome

The Faculty of Intensive Care Medicine and Intensive Care Society Guideline Development Group have used GRADE methodology to make the following recommendations for the management of adult patients with acute respiratory distress syndrome (ARDS). The British Thoracic Society supports the recommendations in this guideline. Where mechanical ventilation is required, the use of low tidal volumes (<6 ml/kg ideal body weight) and airway pressures (plateau pressure <30 cmH2O) was recommended. For patients with moderate/severe ARDS (PF ratio<20 kPa), prone positioning was recommended for at least 12 hours per day. By contrast, high frequency oscillation was not recommended and it was suggested that inhaled nitric oxide is not used. The use of a conservative fluid management strategy was suggested for all patients, whereas mechanical ventilation with high positive end-expiratory pressure and the use of the neuromuscular blocking agent cisatracurium for 48 hours was suggested for patients with ARDS with ratio of arterial oxygen partial pressure to fractional inspired oxygen (PF) ratios less than or equal to 27 and 20 kPa, respectively. Extracorporeal membrane oxygenation was suggested as an adjunct to protective mechanical ventilation for patients with very severe ARDS. In the absence of adequate evidence, research recommendations were made for the use of corticosteroids and extracorporeal carbon dioxide removal.

Moderate to Severe Acute Respiratory Distress Syndrome Management Strategies: A Narrative Review

Acute respiratory distress syndrome (ARDS) remains a common complication associated with significant negative outcomes in critically ill patients. Lung-protective mechanical ventilation strategies remain the cornerstone in the management of ARDS. Several therapeutic options are currently available including fluid management, neuromuscular blocking agents, prone positioning, extracorporeal membrane oxygenation, corticosteroids, and inhaled pulmonary vasodilating agents (prostacyclins and nitric oxide). Unfortunately, an evidence-based, standard-of-care approach in managing ARDS beyond lung-protective ventilation remains elusive, contributing to significant variability in clinical practice. Although the optimal therapeutic strategy for managing moderate to severe ARDS remains extremely controversial, therapies supported with more robust clinical evidence should be considered first. The purpose of this narrative review is to discuss the published clinical evidence for both pharmacologic and nonpharmacologic management strategies in adult patients with moderate to severe ARDS as well as to discuss practical considerations for implementation.

Therapeutic use of mesenchymal stem cell-derived extracellular vesicles in acute lung injury

Acute respiratory distress syndrome is a major cause of respiratory failure in critically ill patients. Despite extensive research into its pathophysiology, mortality remains high. No effective pharmacotherapy exists. Based largely on numerous preclinical animal studies, administration of mesenchymal stem or stromal cell (MSC) as a therapeutic for acute lung injury (ALI) holds great promise, and Phase I and II clinical trials are currently under way internationally. However, concern for the use of stem cells, specifically the risk of iatrogenic tumor formation, as well as the prohibitive cost of production, storage, and distribution of cells in bone marrow transplant facilities, may limit access to this lifesaving therapy. Accumulating evidence now suggest that novel stem cell-derived therapies, including MSC-conditioned medium and extracellular vesicles (EVs) released from MSCs, might constitute compelling alternatives. The current review summarizes the preclinical studies testing MSC EVs as treatment for ALI and other inflammatory lung diseases. While certain logistic obstacles limit the clinical applications of MSC-conditioned medium such as the volume required for treatment and lack of standardization of what constitutes the components of conditioned medium, the therapeutic application of MSC EVs remains promising, primarily due to ability of EVs to maintain the functional phenotype of the parent cell. However, utilization of MSC EVs will require large-scale production and standardization concerning identification, characterization, and quantification.

Optimal duration of prone positioning in patients with acute respiratory distress syndrome: a protocol for a systematic review and meta-regression analysis

INTRODUCTION

Several systematic reviews and meta-analyses have demonstrated that prolonged (≥16 hours) prone positioning can reduce the mortality associated with acute respiratory distress syndrome (ARDS). However, the effectiveness and optimal duration of prone positioning was not fully evaluated. To fill these gaps, we will first investigate the effectiveness of prone positioning compared with the conventional management of patients with ARDS, regarding outcomes using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. Second, if statistical heterogeneity in effectiveness with regard to short-term mortality (intensive care unit death or ≤30-day mortality) is shown, we will conduct a meta-regression analysis to explore the association between duration and effectiveness, and determine the optimal duration of prone positioning.

METHOD AND ANALYSIS

Relevant studies are collected using PubMed/MEDLINE, Embase, Cochrane Central Register of Controlled Trials and the WHO International Clinical Trials Platform Search Portal. Randomised controlled trials comparing prone and supine positioning in adults with ARDS will be included in the meta-analysis. Two independent investigators will screen trials obtained by search eligibility and extract data from selected studies to standardised data recording forms. For each selected trial, the risk of bias and quality of evidence will be evaluated using the GRADE system. Meta-regression analyses will be performed to identify the most important factors associated with short-term mortality, and subgroup analysis will be used to analyse the following: duration of mechanical ventilation in the prone position per day, patient severity, tidal volume and cause of ARDS. If heterogeneity or inconsistency among the studies is detected, subgroup analysis will be conducted on factors that may cause heterogeneity.

ETHICS AND DISSEMINATION

This study requires no ethical approval. The results obtained from this systematic review and meta-analysis will be disseminated through international conference presentations and publication in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42017078340.

Mesenchymal Stem Cell Microvesicles Restore Protein Permeability Across Primary Cultures of Injured Human Lung Microvascular Endothelial Cells

Our previous study demonstrated that mesenchymal stem cell (MSC) microvesicles (MV) reduced lung inflammation, protein permeability, and pulmonary edema in endotoxin-induced acute lung injury in mice. However, the underlying mechanisms for restoring lung protein permeability were not fully understood. In this current study, we hypothesized that MSC MV would restore protein permeability across injured human lung microvascular endothelial cells (HLMVEC) in part through the transfer of angiopoietin-1 (Ang1) mRNA to the injured endothelium. A transwell coculture system was used to study the effect of MSC MV on protein permeability across HLMVECs injured by cytomix, a mixture of IL-1β, TNF-α, and IFN-γ (50 ng/ml). Our result showed that cytomix significantly increased permeability to FITC-dextran (70 kDa) across HLMVECs over 24 hours. Administration of MSC MVs restored this permeability in a dose dependent manner, which was associated with an increase in Ang1 mRNA and protein secretion in the injured endothelium. This beneficial effect was diminished when MSC MV was pretreated with an anti-CD44 antibody, suggesting that internalization of MV into the HLMVEC was required for the therapeutic effect. Fluorescent microscopy showed that MSC MV largely prevented the reorganization of cytoskeleton protein F-actin into "actin stress fiber" and restored the location of the tight junction protein ZO-1 and adherens junction protein VE-cadherin in injured HLMVECs. Ang1 siRNA pretreatment of MSC MV prior to administration to injured HLMVECs eliminated the therapeutic effect of MV. In summary, MSC MVs restored protein permeability across HLMVEC in part by increasing Ang1 secretion by injured HLMVEC. Stem Cells Translational Medicine 2018;7:615-624.

ARDS: challenges in patient care and frontiers in research

This review discusses the clinical challenges associated with ventilatory support and pharmacological interventions in patients with acute respiratory distress syndrome (ARDS). In addition, it discusses current scientific challenges facing researchers when planning and performing trials of ventilatory support or pharmacological interventions in these patients.

Noninvasive mechanical ventilation is used in some patients with ARDS. When intubated and mechanically ventilated, ARDS patients should be ventilated with low tidal volumes. A plateau pressure <30 cmH₂O is recommended in all patients. It is suggested that a plateau pressure <15 cmH₂O should be considered safe. Patient with moderate and severe ARDS should receive higher levels of positive end-expiratory pressure (PEEP). Rescue therapies include prone position and neuromuscular blocking agents. Extracorporeal support for decapneisation and oxygenation should only be considered when lung-protective ventilation is no longer possible, or in cases of refractory hypoxaemia, respectively. Tracheotomy is only recommended when prolonged mechanical ventilation is expected.

Of all tested pharmacological interventions for ARDS, only treatment with steroids is considered to have benefit.

Proper identification of phenotypes, known to respond differently to specific interventions, is increasingly considered important for clinical trials of interventions for ARDS. Such phenotypes could be defined based on clinical parameters, such as the arterial oxygen tension/inspiratory oxygen fraction ratio, but biological marker profiles could be more promising.

Treatment of ARDS is mainly through the prevention of ventilation-induced lung injuryhttp://ow.ly/DeJC30hGWfi

Noninvasive Ventilation in Acute Hypoxemic Nonhypercapnic Respiratory Failure: A Systematic Review and Meta-Analysis

Supplemental Digital Content is available in the text.

Objective:

To evaluate the effectiveness of noninvasive ventilation in patients with acute hypoxemic nonhypercapnic respiratory failure unrelated to exacerbation of chronic obstructive pulmonary disease and cardiogenic pulmonary edema.

Data Sources:

PubMed, EMBASE, Cochrane library, Web of Science, and bibliographies of articles were retrieved inception until June 2016.

Study Selection:

Randomized controlled trials comparing application of noninvasive ventilation with standard oxygen therapy in adults with acute hypoxemic nonhypercapnic respiratory failure were included. Chronic obstructive pulmonary disease exacerbation and cardiogenic pulmonary edema patients were excluded. The primary outcome was intubation rate; ICU mortality and hospital mortality were secondary outcomes.

Data Extraction:

Demographic variables, noninvasive ventilation application, and outcomes were retrieved. Internal validity was assessed using the risk of bias tool. The strength of evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation methodology.

Data Synthesis:

Eleven studies (1,480 patients) met the inclusion criteria and were analyzed by using a random effects model. Compared with standard oxygen therapy, the pooled effect showed that noninvasive ventilation significantly reduced intubation rate with a summary risk ratio of 0.59 (95% CI, 0.44–0.79; p = 0.0004). Furthermore, hospital mortality was also significantly reduced (risk ratio, 0.46; 95% CI, 0.24–0.87; p = 0.02). Subgroup meta-analysis showed that the application of bilevel positive support ventilation (bilevel positive airway pressure) was associated with a reduction in ICU mortality (p = 0.007). Helmet noninvasive ventilation could reduce hospital mortality (p = 0.0004), whereas face/nasal mask noninvasive ventilation could not.

Conclusions:

Noninvasive ventilation decreased endotracheal intubation rates and hospital mortality in acute hypoxemia nonhypercapnic respiratory failure excluding chronic obstructive pulmonary disease exacerbation and cardiogenic pulmonary edema patients. There is no sufficient scientific evidence to recommend bilevel positive airway pressure or helmet due to the limited number of trials available. Large rigorous randomized trials are needed to answer these questions definitely.

The clinical practice guideline for the management of ARDS in Japan

BACKGROUND

The Japanese Society of Respiratory Care Medicine and the Japanese Society of Intensive Care Medicine provide here a clinical practice guideline for the management of adult patients with ARDS in the ICU.

METHOD

The guideline was developed applying the GRADE system for performing robust systematic reviews with plausible recommendations. The guideline consists of 13 clinical questions mainly regarding ventilator settings and drug therapies (the last question includes 11 medications that are not approved for clinical use in Japan).

RESULTS

The recommendations for adult patients with ARDS include: we suggest against early tracheostomy (GRADE 2C), we suggest using NPPV for early respiratory management (GRADE 2C), we recommend the use of low tidal volumes at 6-8 mL/kg (GRADE 1B), we suggest setting the plateau pressure at 30cmH20 or less (GRADE2B), we suggest using PEEP within the range of plateau pressures less than or equal to 30cmH2O, without compromising hemodynamics (Grade 2B), and using higher PEEP levels in patients with moderate to severe ARDS (Grade 2B), we suggest using protocolized methods for liberation from mechanical ventilation (Grade 2D), we suggest prone positioning especially in patients with moderate to severe respiratory dysfunction (GRADE 2C), we suggest against the use of high frequency oscillation (GRADE 2C), we suggest the use of neuromuscular blocking agents in patients requiring mechanical ventilation under certain circumstances (GRADE 2B), we suggest fluid restriction in the management of ARDS (GRADE 2A), we do not suggest the use of neutrophil elastase inhibitors (GRADE 2D), we suggest the administration of steroids, equivalent to methylprednisolone 1-2mg/kg/ day (GRADE 2A), and we do not recommend other medications for the treatment of adult patients with ARDS (GRADE1B; inhaled/intravenous β2 stimulants, prostaglandin E1, activated protein C, ketoconazole, and lisofylline, GRADE 1C; inhaled nitric oxide, GRADE 1D; surfactant, GRADE 2B; granulocyte macrophage colony-stimulating factor, N-acetylcysteine, GRADE 2C; Statin.).

CONCLUSIONS

This article was translated from the Japanese version originally published as the ARDS clinical practice guidelines 2016 by the committee of ARDS clinical practice guideline (Tokyo, 2016, 293p, available from http://www.jsicm.org/ARDSGL/ARDSGL2016.pdf). The original article, written for Japanese healthcare providers, provides points of view that are different from those in other countries.

Recommendations of the Working Groups from the Spanish Society of Intensive and Critical Care Medicine and Coronary Units (SEMICYUC) for the management of adult critically ill patients

The standardization of the Intensive Care Medicine may improve the management of the adult critically ill patient. However, these strategies have not been widely applied in the Intensive Care Units (ICUs). The aim is to elaborate the recommendations for the standardization of the treatment of critical patients. A panel of experts from the thirteen working groups (WG) of the Spanish Society of Intensive and Critical Care Medicine and Coronary Units (SEMICYUC) was selected and nominated by virtue of clinical expertise and/or scientific experience to carry out the recommendations. Available scientific literature in the management of adult critically ill patients from 2002 to 2016 was extracted. The clinical evidence was discussed and summarised by the experts in the course of a consensus finding of every WG and finally approved by the WGs after an extensive internal review process that was carried out between December 2015 and December 2016. A total of 65 recommendations were developed, of which 5 corresponded to each of the 13 WGs. These recommendations are based on the opinion of experts and scientific knowledge, and are intended as a guide for the intensivists in the management of critical patients.

Identification and validation of distinct biological phenotypes in patients with acute respiratory distress syndrome by cluster analysis

RATIONALE

We hypothesised that patients with acute respiratory distress syndrome (ARDS) can be clustered based on concentrations of plasma biomarkers and that the thereby identified biological phenotypes are associated with mortality.

METHODS

Consecutive patients with ARDS were included in this prospective observational cohort study. Cluster analysis of 20 biomarkers of inflammation, coagulation and endothelial activation provided the phenotypes in a training cohort, not taking any outcome data into account. Logistic regression with backward selection was used to select the most predictive biomarkers, and these predicted phenotypes were validated in a separate cohort. Multivariable logistic regression was used to quantify the independent association with mortality.

RESULTS

Two phenotypes were identified in 454 patients, which we named 'uninflamed' (N=218) and 'reactive' (N=236). A selection of four biomarkers (interleukin-6, interferon gamma, angiopoietin 1/2 and plasminogen activator inhibitor-1) could be used to accurately predict the phenotype in the training cohort (area under the receiver operating characteristics curve: 0.98, 95% CI 0.97 to 0.99). Mortality rates were 15.6% and 36.4% (p<0.001) in the training cohort and 13.6% and 37.5% (p<0.001) in the validation cohort (N=207). The 'reactive phenotype' was independent from confounders associated with intensive care unit mortality (training cohort: OR 1.13, 95% CI 1.04 to 1.23; validation cohort: OR 1.18, 95% CI 1.06 to 1.31).

CONCLUSIONS

Patients with ARDS can be clustered into two biological phenotypes, with different mortality rates. Four biomarkers can be used to predict the phenotype with high accuracy. The phenotypes were very similar to those found in cohorts derived from randomised controlled trials, and these results may improve patient selection for future clinical trials targeting host response in patients with ARDS.

Clinical Practice Guideline of Acute Respiratory Distress Syndrome

There is no well-stated practical guideline for mechanically ventilated patients with or without acute respiratory distress syndrome (ARDS). We generate strong (1) and weak (2) grade of recommendations based on high (A), moderate (B) and low (C) grade in the quality of evidence. In patients with ARDS, we recommend low tidal volume ventilation (1A) and prone position if it is not contraindicated (1B) to reduce their mortality. However, we did not support high-frequency oscillatory ventilation (1B) and inhaled nitric oxide (1A) as a standard treatment. We also suggest high positive end-expiratory pressure (2B), extracorporeal membrane oxygenation as a rescue therapy (2C), and neuromuscular blockage for 48 hours after starting mechanical ventilation (2B). The application of recruitment maneuver may reduce mortality (2B), however, the use of systemic steroids cannot reduce mortality (2B). In mechanically ventilated patients, we recommend light sedation (1B) and low tidal volume even without ARDS (1B) and suggest lung protective ventilation strategy during the operation to lower the incidence of lung complications including ARDS (2B). Early tracheostomy in mechanically ventilated patients can be performed only in limited patients (2A). In conclusion, of 12 recommendations, nine were in the management of ARDS, and three for mechanically ventilated patients.

The Vascular Endothelial Growth Factors-Expressing Character of Mesenchymal Stem Cells Plays a Positive Role in Treatment of Acute Lung Injury In Vivo

Recently, mesenchymal stem cells (MSC) have been proved to be beneficial in acute respiratory distress syndrome (ARDS). Vascular endothelial growth factor (VEGF) is an important angiogenesis factor that MSC release. However, the precise role of VEGF-expressing character of MSC in the MSC treatment for ARDS remains obscure. Here, we firstly knocked down the gene VEGF in MSC (MSC-ShVEGF) with lentiviral transduction. Then we injected the MSC-ShVEGF to rats with lipopolysaccharide-induced acute lung injury (ALI) via the tail vein. Data showed that MSC transplantation significantly increased VEGF levels in the lung, reduced lung permeability, protected lung endothelium from apoptosis, facilitated VE-cadherin recovery, controlled inflammation, and attenuated lung injury. However, VEGF gene knockdown in MSC led to relatively insufficient VEGF expression in the injured lung and significantly diminished the therapeutic effects of MSC on ALI, suggesting an important role of VEGF-expressing behavior of MSC in the maintenance of VEGF in the lung and the MSC treatment for ALI. Hence, we conclude that MSC restores the lung permeability and attenuates lung injury in rats with ALI in part by maintaining a “sufficient” VEGF level in the lung and the VEGF-expressing character of MSC plays a positive role in the therapeutic effects of MSC on ARDS.

Prone Positioning in Cardiac Surgery: For Many, But Not for Everyone

Prone positioning is a therapeutic maneuver to improve arterial oxygenation in patients with acute lung injury that is not implemented in most centers performing adult cardiac surgery. The aim of this study was to review our experience with prone positioning to assess the effects of this maneuver in patients with postoperative acute respiratory failure. From 2010-2014, 127 adult patients with postoperative acute respiratory failure were treated with prone positioning in addition to specific therapy. Univariate and multivariate logistic regression analyses were performed to identify independent risk factors associated with in-hospital mortality. In-hospital mortality was 22.8% (n = 29). No significant differences were observed in preoperative risk factors between patients who survived (S) and those who died (D), except for age (62.7 ± 11.2 vs 70.2 ± 11.3; P = 0.007-at multivariate analysis P = 0.03, odds ratio [OR] = 1.1/year). Preproning values of PaO₂/FiO₂ were significantly different between groups (D vs S: 115 ± 46 vs 150 ± 56; P = 0.006), but only preproning FiO₂ remained highly significant at multivariate analysis (D vs S: 0.82 ± 0.18 vs 0.67 ± 0.16; P = 0.001, OR = 1.07; with FiO₂ > 0.75 vs < 75, OR = 19.6). D showed a higher improvement of PaO₂/FiO₂ immediately after prone positioning (207 ± 100 vs 219 ± 90, P = 0.56; within-group analysis between preproning and 1 hour after proning: S-P = 0.49, D-P = 0.019; at 12 hours: 286 ± 123 vs 240 ± 120, P = 0.06; within-group analysis between 1 hour and 12 hours after proning: S-P = 0.15; D-P = 0.17; between groups-P = 0.05). D had higher peak WBC count (26 ± 9.8 vs 17.7 ± 5.9×10³/mL; P = 0.0001) and a higher rate of low output syndrome (15 vs 9 patients-51.7% vs 9.2%; P = 0.0001). At multivariate analysis, white blood cell count: P = 0.005, OR = 1.11/10³ white blood cell; low output syndrome: P = 0.0002, OR = 20.5. In conclusion, our results show that prone positioning, if performed early, is a safe and effective adjunct measure for patients with postoperative acute hypoxemic respiratory failure of noncardiogenic origin.

Mesenchymal stem cell derived secretome and extracellular vesicles for acute lung injury and other inflammatory lung diseases

INTRODUCTION

Acute respiratory distress syndrome is a major cause of respiratory failure in critically ill patients. Despite extensive research into its pathophysiology, mortality remains high. No effective pharmacotherapy exists. Based largely on numerous preclinical studies, administration of mesenchymal stem or stromal cell (MSC) as a therapeutic for acute lung injury holds great promise, and clinical trials are currently underway. However, concern for the use of stem cells, specifically the risk of iatrogenic tumor formation, remains unresolved. Accumulating evidence now suggest that novel cell-free therapies including MSC-derived conditioned medium and extracellular vesicles released from MSCs might constitute compelling alternatives.

AREAS COVERED

The current review summarizes the preclinical studies testing MSC conditioned medium and/or MSC extracellular vesicles as treatment for acute lung injury and other inflammatory lung diseases.

EXPERT OPINION

While certain logistical obstacles limit the clinical applications of MSC conditioned medium such as the volume required for treatment, the therapeutic application of MSC extracellular vesicles remains promising, primarily due to ability of extracellular vesicles to maintain the functional phenotype of the parent cell. However, utilization of MSC extracellular vesicles will require large-scale production and standardization concerning identification, characterization and quantification.

Venovenous Extracorporeal Membrane Oxygenation in Intractable Pulmonary Insufficiency: Practical Issues and Future Directions

Venovenous extracorporeal membrane oxygenation (vv-ECMO) is a highly invasive method for organ support that is gaining in popularity due to recent technical advances and its successful application in the recent H1N1 epidemic. Although running a vv-ECMO program is potentially feasible for many hospitals, there are many theoretical concepts and practical issues that merit attention and require expertise. In this review, we focus on indications for vv-ECMO, components of the circuit, and management of patients on vv-ECMO. Concepts regarding oxygenation and decarboxylation and how they can be influenced are discussed. Day-to-day management, weaning, and most frequent complications are covered in light of the recent literature.

Lung Circulation

The circulation of the lung is unique both in volume and function. For example, it is the only organ with two circulations: the pulmonary circulation, the main function of which is gas exchange, and the bronchial circulation, a systemic vascular supply that provides oxygenated blood to the walls of the conducting airways, pulmonary arteries and veins. The pulmonary circulation accommodates the entire cardiac output, maintaining high blood flow at low intravascular arterial pressure. As compared with the systemic circulation, pulmonary arteries have thinner walls with much less vascular smooth muscle and a relative lack of basal tone. Factors controlling pulmonary blood flow include vascular structure, gravity, mechanical effects of breathing, and the influence of neural and humoral factors. Pulmonary vascular tone is also altered by hypoxia, which causes pulmonary vasoconstriction. If the hypoxic stimulus persists for a prolonged period, contraction is accompanied by remodeling of the vasculature, resulting in pulmonary hypertension. In addition, genetic and environmental factors can also confer susceptibility to development of pulmonary hypertension. Under normal conditions, the endothelium forms a tight barrier, actively regulating interstitial fluid homeostasis. Infection and inflammation compromise normal barrier homeostasis, resulting in increased permeability and edema formation. This article focuses on reviewing the basics of the lung circulation (pulmonary and bronchial), normal development and transition at birth and vasoregulation. Mechanisms contributing to pathological conditions in the pulmonary circulation, in particular when barrier function is disrupted and during development of pulmonary hypertension, will also be discussed.

Prone position for acute respiratory failure in adults

BACKGROUND

Acute hypoxaemia de novo or on a background of chronic hypoxaemia is a common reason for admission to intensive care and for provision of mechanical ventilation. Various refinements of mechanical ventilation or adjuncts are employed to improve patient outcomes. Mortality from acute respiratory distress syndrome, one of the main contributors to the need for mechanical ventilation for hypoxaemia, remains approximately 40%. Ventilation in the prone position may improve lung mechanics and gas exchange and could improve outcomes.

OBJECTIVES

The objectives of this review are (1) to ascertain whether prone ventilation offers a mortality advantage when compared with traditional supine or semi recumbent ventilation in patients with severe acute respiratory failure requiring conventional invasive artificial ventilation, and (2) to supplement previous systematic reviews on prone ventilation for hypoxaemic respiratory failure in an adult population.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 1), Ovid MEDLINE (1950 to 31 January 2014), EMBASE (1980 to 31 January 2014), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to 31 January 2014) and Latin American Caribbean Health Sciences Literature (LILACS) (1992 to 31 January 2014) in Ovid MEDLINE for eligible randomized controlled trials. We also searched for studies by handsearching reference lists of relevant articles, by contacting colleagues and by handsearching published proceedings of relevant journals. We applied no language constraints, and we reran the searches in CENTRAL, MEDLINE, EMBASE, CINAHL and LILACS in June 2015. We added five new studies of potential interest to the list of "Studies awaiting classification" and will incorporate them into formal review findings during the review update.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that examined the effects of prone position versus supine/semi recumbent position during conventional mechanical ventilation in adult participants with acute hypoxaemia.

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed all trials identified by the search and assessed them for suitability, methods and quality. Two review authors extracted data, and three review authors reviewed the data extracted. We analysed data using Review Manager software and pooled included studies to determine the risk ratio (RR) for mortality and the risk ratio or mean difference (MD) for secondary outcomes; we also performed subgroup analyses and sensitivity analyses.

MAIN RESULTS

We identified nine relevant RCTs, which enrolled a total of 2165 participants (10 publications). All recruited participants suffered from disorders of lung function causing moderate to severe hypoxaemia and requiring mechanical ventilation, so they were fairly comparable, given the heterogeneity of specific disease diagnoses in intensive care. Risk of bias, although acceptable in the view of the review authors, was inevitable: Blinding of participants and carers to treatment allocation was not possible (face-up vs face-down).Primary analyses of short- and longer-term mortality pooled from six trials demonstrated an RR of 0.84 to 0.86 in favour of the prone position (PP), but findings were not statistically significant: In the short term, mortality for those ventilated prone was 33.4% (363/1086) and supine 38.3% (395/1031). This resulted in an RR of 0.84 (95% confidence interval (CI) 0.69 to 1.02) marginally in favour of PP. For longer-term mortality, results showed 41.7% (462/1107) for prone and 47.1% (490/1041) for supine positions, with an RR of 0.86 (95% CI 0.72 to 1.03). The quality of the evidence for both outcomes was rated as low as a result of important potential bias and serious inconsistency.Subgroup analyses for mortality identified three groups consistently favouring PP: those recruited within 48 hours of meeting entry criteria (five trials; 1024 participants showed an RR of 0.75 (95% CI 0.59 to 94)); those treated in the PP for 16 or more hours per day (five trials; 1005 participants showed an RR of 0.77 (95% CI 0.61 to 0.99)); and participants with more severe hypoxaemia at trial entry (six trials; 1108 participants showed an RR of 0.77 (95% CI 0.65 to 0.92)). The quality of the evidence for these outcomes was rated as moderate as a result of potentially important bias.Prone positioning appeared to influence adverse effects: Pressure sores (three trials; 366 participants) with an RR of 1.37 (95% CI 1.05 to 1.79) and tracheal tube obstruction with an RR of 1.78 (95% CI 1.22 to 2.60) were increased with prone ventilation. Reporting of arrhythmias was reduced with PP, with an RR of 0.64 (95% CI 0.47 to 0.87).

AUTHORS' CONCLUSIONS

We found no convincing evidence of benefit nor harm from universal application of PP in adults with hypoxaemia mechanically ventilated in intensive care units (ICUs). Three subgroups (early implementation of PP, prolonged adoption of PP and severe hypoxaemia at study entry) suggested that prone positioning may confer a statistically significant mortality advantage. Additional adequately powered studies would be required to confirm or refute these possibilities of subgroup benefit but are unlikely, given results of the most recent study and recommendations derived from several published subgroup analyses. Meta-analysis of individual patient data could be useful for further data exploration in this regard. Complications such as tracheal obstruction are increased with use of prone ventilation. Long-term mortality data (12 months and beyond), as well as functional, neuro-psychological and quality of life data, are required if future studies are to better inform the role of PP in the management of hypoxaemic respiratory failure in the ICU.

Ventilator Strategies and Rescue Therapies for Management of Acute Respiratory Failure in the Emergency Department

Acute respiratory failure is commonly encountered in the emergency department (ED), and early treatment can have effects on long-term outcome. Noninvasive ventilation is commonly used for patients with respiratory failure and has been demonstrated to improve outcomes in acute exacerbations of chronic obstructive lung disease and congestive heart failure, but should be used carefully, if at all, in the management of asthma, pneumonia, and acute respiratory distress syndrome. Lung-protective tidal volumes should be used for all patients receiving mechanical ventilation, and FiO2 should be reduced after intubation to achieve a goal of less than 60%. For refractory hypoxemia, new rescue therapies have emerged to help improve the oxygenation, and in some cases mortality, and should be considered in ED patients when necessary, as deferring until ICU admission may be deleterious. This review article summarizes the pathophysiology of acute respiratory failure, management options, and rescue therapies including airway pressure release ventilation, continuous neuromuscular blockade, inhaled nitric oxide, and extracorporeal membrane oxygenation.

The efficacy and safety of prone positioning in adults patients with acute respiratory distress syndrome: a meta-analysis of randomized controlled trials

BACKGROUND

Prone positioning for acute respiratory distress syndrome (ARDS) has no impact on mortality despite significant improvements in oxygenation. However, a recent trial demonstrated reduced mortality rates in the prone position for severe ARDS. We evaluated effects of prone position duration and protective lung strategies on mortality rates in ARDS.

METHODS

We extensively searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials to identify randomized controlled trials (RCTs) reporting on prone positioning during acute respiratory failure in adults for inclusion in our meta-analysis.

RESULTS

Eight trials met our inclusion criteria, Totals of 1,099 and 1,042 patients were randomized to the prone and supine ventilation positions. The mortality rates associated with the prone and supine positions were 41% and 47% [risk ratio (RR), 0.90; 95% confidence interval (CI), 0.82-0.98, P=0.02], but the heterogeneity was moderate (P=0.01, I(2)=61%). In a subgroup analysis, the mortality rates for lung protective ventilation (RR 0.73, 95% CI, 0.62-0.86, P=0.0002) and duration of prone positioning >12 h (RR 0.75, 95% CI, 0.65-0.87, P<0.0001) were reduced in the prone position. Prone positioning was not associated with an increased incidence of cardiac events (RR 1.01, 95% CI, 0.87-1.17) or ventilator associated pneumonia (RR 0.88, 95% CI, 0.71-1.09), but it was associated with an increased incidence of pressure sores (RR 1.23, 95% CI, 1.07-1.41) and endotracheal dislocation (RR 1.33, 95% CI, 1.02-1.74).

CONCLUSIONS

Prone positioning tends to reduce the mortality rates in ARDS patients, especially when used in conjunction with a lung protective strategy and longer prone position durations. Prone positioning for ARDS patients should be prioritized over other invasive procedures because related life-threatening complications are rare. However, further additional randomized controlled design to study are required for confirm benefit of prone position in ARDS.