Effects of alveolar recruitment maneuvers on clinical outcomes in patients with acute respiratory distress syndrome: a systematic review and meta-analysis

Recruitment-Potential-Oriented Mechanical Ventilation Protocol and Narrative Review for Patients with Acute Respiratory Distress Syndrome

Even though much progress has been made to improve clinical outcomes, acute respiratory distress syndrome (ARDS) remains a significant cause of acute respiratory failure. Protective mechanical ventilation is the backbone of supportive care for these patients; however, there are still many unresolved issues in its setting. The primary goal of mechanical ventilation is to improve oxygenation and ventilation. The use of positive pressure, especially positive end-expiratory pressure (PEEP), is mandatory in this approach. However, PEEP is a double-edged sword. How to safely set positive end-inspiratory pressure has long been elusive to clinicians. We hereby propose a pressure-volume curve measurement-based method to assess whether injured lungs are recruitable in order to set an appropriate PEEP. For the most severe form of ARDS, extracorporeal membrane oxygenation (ECMO) is considered as the salvage therapy. However, the high level of medical resources required and associated complications make its use in patients with severe ARDS controversial. Our proposed protocol also attempts to propose how to improve patient outcomes by balancing the possible overuse of resources with minimizing patient harm due to dangerous ventilator settings. A recruitment-potential-oriented evaluation-based protocol can effectively stabilize hypoxemic conditions quickly and screen out truly serious patients.

Pulmonary expansion manoeuvres compared to usual care on ventilatory mechanics, oxygenation, length of mechanical ventilation and hospital stay, extubation, atelectasis, and mortality of patients in mechanical ventilation: A randomized clinical trial

Pulmonary expansion manoeuvres are therapeutic techniques used to prevent and reverse atelectasis; however, no randomized controlled trials have provided evidence supporting the use of this intervention among individuals on mechanical ventilation.

OBJECTIVE

To evaluate the effects of chest compression-decompression and chest block manoeuvres compared to usual care among patients on mechanical ventilation.

METHODS

The current study was a randomized clinical trial of adult subjects on mechanical ventilation for 12 to 48 hours. The control group received usual care (passive or active mobilization, manoeuvres for airway clearance and tracheal aspiration). The intervention group received usual care plus two lung expansion manoeuvres, i.e., chest decompression and chest block, while remaining on mechanical ventilation. Assessments were performed before and after usual care, immediately after the intervention and 30 minutes after the intervention. The primary outcome was static compliance. The secondary outcomes were the incidence of atelectasis, dynamic compliance, airway resistance, driving pressure, oxygenation, duration of mechanical ventilation, extubation success, length of hospital and ICU stay, and mortality.

RESULTS

Fifty-one participants (67±15 years old, 53% men, 26 in the control group and 25 in the intervention group) were evaluated. No differences in static compliance were observed between groups (intervention minus control) before and after expansion manoeuvres [3.64 ml/cmH2O (95% CI: -0.36-7.65, p = 0.074)]. Peripheral oxygen saturation differed between groups before and after expansion manoeuvres, with more favourable outcome observed in the control group [-1.04% (95% CI: -1.94 --0.14), p = 0.027]. No differences were found in other outcomes.

CONCLUSION

Chest compression-decompression and chest block manoeuvres did not improve ventilatory mechanics, the incidence of atelectasis, oxygenation, the duration of mechanical ventilation, the length of stay in the ICU and hospital, or mortality in individuals on mechanical ventilation. The findings of this study can be valuable for guiding evidence-based clinical practice and developing a therapeutic approach that provides real benefits for this population.

Individualized PEEP without Recruitment Maneuvers Improves Intraoperative Oxygenation: A Randomized Controlled Study

Individualized positive end-expiratory pressure (PEEP) combined with recruitment maneuvers improves intraoperative oxygenation in individuals undergoing robot-assisted prostatectomy. However, whether electrical impedance tomography (EIT)-guided individualized PEEP without recruitment maneuvers can also improve intraoperative oxygenation is unknown. To test this, fifty-six male patients undergoing elective robot-assisted laparoscopic prostatectomy were randomly assigned to either individualized PEEP (Group PEEPIND, n = 28) or a control with a fixed PEEP of 5 cm H2O (Group PEEP5, n = 28). Individualized PEEP was guided by EIT after placing the patients in the Trendelenburg position and performing intraperitoneal insufflation. Patients in Group PEEPIND maintained individualized PEEP without intermittent recruitment maneuvers, and those in Group PEEP5 maintained a PEEP of 5 cm H2O intraoperatively. Both groups were extubated in a semi-sitting position once the extubation criteria were met. The primary outcome was arterial oxygen partial pressure (PaO2)/inspiratory oxygen fraction (FiO2) prior to extubation. Other outcomes included intraoperative driving pressure, plateau pressure and dynamic, respiratory system compliance, and the incidence of postoperative hypoxemia in the post-operative care unit (PACU). Our results showed that the intraoperative median for PEEPIND was 16 cm H2O (ranging from 12 to 18 cm H2O). EIT-guided PEEPIND was associated with higher PaO2/FiO2 before extubation compared to PEEP5 (71.6 ± 10.7 vs. 56.8 ± 14.1 kPa, p = 0.003). Improved oxygenation extended into the PACU with a lower incidence of postoperative hypoxemia (3.8% vs. 26.9%, p = 0.021). Additionally, PEEPIND was associated with lower driving pressures (12.0 ± 3.0 vs. 15.0 ± 4.4 cm H2O, p = 0.044) and better compliance (44.5 ± 12.8 vs. 33.6 ± 9.1 mL/cm H2O, p = 0.017). Our data indicated that individualized PEEP guided by EIT without intraoperative recruitment maneuvers also improved perioperative oxygenation in patients undergoing robot-assisted laparoscopic radical prostatectomy, which could benefit patients with the risk of intraoperative hemodynamic instability caused by recruitment maneuvers. Trial registration: China Clinical Trial Registration Center Identifier: ChiCTR2100053839. This study was registered on 1 December 2021. The first patient was recruited on 15 December 2021.

Management of severe acute respiratory distress syndrome: a primer

This narrative review explores the physiology and evidence-based management of patients with severe acute respiratory distress syndrome (ARDS) and refractory hypoxemia, with a focus on mechanical ventilation, adjunctive therapies, and veno-venous extracorporeal membrane oxygenation (V-V ECMO). Severe ARDS cases increased dramatically worldwide during the Covid-19 pandemic and carry a high mortality. The mainstay of treatment to improve survival and ventilator-free days is proning, conservative fluid management, and lung protective ventilation. Ventilator settings should be individualized when possible to improve patient-ventilator synchrony and reduce ventilator-induced lung injury (VILI). Positive end-expiratory pressure can be individualized by titrating to best respiratory system compliance, or by using advanced methods, such as electrical impedance tomography or esophageal manometry. Adjustments to mitigate high driving pressure and mechanical power, two possible drivers of VILI, may be further beneficial. In patients with refractory hypoxemia, salvage modes of ventilation such as high frequency oscillatory ventilation and airway pressure release ventilation are additional options that may be appropriate in select patients. Adjunctive therapies also may be applied judiciously, such as recruitment maneuvers, inhaled pulmonary vasodilators, neuromuscular blockers, or glucocorticoids, and may improve oxygenation, but do not clearly reduce mortality. In select, refractory cases, the addition of V-V ECMO improves gas exchange and modestly improves survival by allowing for lung rest. In addition to VILI, patients with severe ARDS are at risk for complications including acute cor pulmonale, physical debility, and neurocognitive deficits. Even among the most severe cases, ARDS is a heterogeneous disease, and future studies are needed to identify ARDS subgroups to individualize therapies and advance care.

Multifaceted Roles of Chemokine C-X-C Motif Ligand 7 in Inflammatory Diseases and Cancer

Over recent years, C-X-C motif ligand 7 (CXCL7) has received widespread attention as a chemokine involved in inflammatory responses. Abnormal production of the chemokine CXCL7 has been identified in different inflammatory diseases; nevertheless, the exact role of CXCL7 in the pathogenesis of inflammatory diseases is not fully understood. Persistent infection or chronic inflammation can induce tumorigenesis and progression. Previous studies have shown that the pro-inflammatory chemokine CXCL7 is also expressed by malignant tumor cells and that binding of CXCL7 to its cognate receptors C-X-C chemokine receptor 1 (CXCR1) and C-X-C chemokine receptor 2 (CXCR2) can influence tumor biological behavior (proliferation, invasion, metastasis, and tumor angiogenesis) in an autocrine and paracrine manner. CXCL7 and its receptor CXCR1/CXCR2, which are aberrantly expressed in tumors, may represent new targets for clinical tumor immunotherapy.

Accelerated versus watchful waiting strategy of kidney replacement therapy for acute kidney injury: a systematic review and meta-analysis of randomized clinical trials

Background

Critically ill patients with severe acute kidney injury (AKI) requiring kidney replacement therapy (KRT) have a grim prognosis. Recently, multiple studies focused on the impact of KRT initiation time [i.e., accelerated versus watchful waiting KRT initiation (WWS-KRT)] on patient outcomes. We aim to review the results of all related clinical trials.

Methods

In this systematic review, we searched all relevant randomized clinical trials from January 2000 to April 2021. We assessed the impacts of accelerated versus WWS-KRT on KRT dependence, KRT-free days, mortality and adverse events, including hypotension, infection, arrhythmia and bleeding. We rated the certainty of evidence according to Cochrane methods and the GRADE approach.

Results

A total of 4932 critically ill patients with AKI from 10 randomized clinical trials were included in this analysis. The overall 28-day mortality rate was 38.5%. The 28-day KRT-dependence rate was 13.0%. The overall incident of KRT in the accelerated group was 97.4% and 62.8% in the WWS-KRT group. KRT in the accelerated group started 36.7 h earlier than the WWS-KRT group. The two groups had similar risks of 28-day [pooled log odds ratio (OR) 1.001, P = 0.982] and 90-day (OR 0.999, P = 0.991) mortality rates. The accelerated group had a significantly higher risk of 90-day KRT dependence (OR 1.589, P = 0.007), hypotension (OR 1.687, P < 0.001) and infection (OR 1.38, P = 0.04) compared with the WWS-KRT group.

Conclusions

This meta-analysis revealed that accelerated KRT leads to a higher probability of 90-day KRT dependence and dialysis-related complications without any impact on mortality rate when compared with WWS-KRT. Therefore, we suggest the WWS-KRT strategy for critically ill patients.

Optimizing Mechanical Ventilation in Refractory ARDS

Mechanical ventilation in patients with refractory acute respiratory distress syndrome (ARDS) must provide lung protection. This is achieved by limiting tidal volume (VT) and plateau pressure (Pplat). With the current evidence available VT should be initially set around 6 mL per kg predicted body weight and PPlat maintained below 30 cmH₂O and monitored. Positive end-expiratory pressure (PEEP), which also contributes to lung protection, should be set > 12 cmH₂O, provided oxygenation gets improved, with same Pplat target. Recruitment maneuvers should be used with caution avoiding higher PEEP. Neuromuscular blockade should be started and prone position performed for sessions longer than 16 h. High frequency oscillation ventilation should be used in expert centers only if previous management failed to improve oxygenation.

Higher PEEP for acute respiratory distress syndrome: a Bayesian meta-analysis of randomised clinical trials

Objective: Benefit or harm of higher positive end expiratory pressure (PEEP) for acute respiratory distress syndrome (ARDS) is controversial. We aimed to assess the impact of higher levels of PEEP in patients with ARDS under a Bayesian framework. Design: Systematic review and Bayesian meta-analysis of randomised clinical trials comparing higher to lower PEEP in adult patients with ARDS. Data sources: MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials from 1996 to 1 March 2020. Review methods: We extracted data from high quality randomised clinical trials comparing higher to lower levels of PEEP in adult patients, using low tidal volume in both arms, and conducted a Bayesian meta-analysis using aggregate data from these studies. Results: Eight clinical trials including 3703 patients (n = 1833 for higher PEEP, n = 1870 for lower PEEP) were included. Under a minimally informative prior, the posterior probability of benefit with higher PEEP was 65% (relative risk, 0.97 [95% credible interval, 0.78-1.14]). In patients with moderate-to- severe ARDS, the posterior probability of benefit with higher PEEP was 77% (relative risk, 0.94 [95% credible interval, 0.77-1.13]). Down-weighting studies that employed a maximum recruitment strategy by 100% increased the posterior probability of benefit to 92% under a minimally informative prior. Conclusions: The probability of benefit or harm from routine use of higher PEEP for patients with ARDS ranges from 27% to 86%, and from 14% to 73% depending on one's prior, suggesting continued uncertainty and equipoise regarding the benefit of PEEP If data from trials using a maximum recruitment strategy is discounted to some extent because of uncertainty over the appropriateness of this approach, the available evidence suggests that higher PEEP could be beneficial for moderate-to-severe ARDS. However, well powered randomised clinical trials are needed to confirm these findings.

Using Bayesian Methods to Augment the Interpretation of Critical Care Trials. An Overview of Theory and Example Reanalysis of the Alveolar Recruitment for Acute Respiratory Distress Syndrome Trial

Most randomized trials are designed and analyzed using frequentist statistical approaches such as null hypothesis testing and P values. Conceptually, P values are cumbersome to understand, as they provide evidence of data incompatibility with a null hypothesis (e.g., no clinical benefit) and not direct evidence of the alternative hypothesis (e.g., clinical benefit). This counterintuitive framework may contribute to the misinterpretation that the absence of evidence is equal to evidence of absence and may cause the discounting of potentially informative data. Bayesian methods provide an alternative, probabilistic interpretation of data. The reanalysis of completed trials using Bayesian methods is becoming increasingly common, particularly for trials with effect estimates that appear clinically significant despite P values above the traditional threshold of 0.05. Statistical inference using Bayesian methods produces a distribution of effect sizes that would be compatible with observed trial data, interpreted in the context of prior assumptions about an intervention (called "priors"). These priors are chosen by investigators to reflect existing beliefs and past empirical evidence regarding the effect of an intervention. By calculating the likelihood of clinical benefit, a Bayesian reanalysis can augment the interpretation of a trial. However, if priors are not defined a priori, there is a legitimate concern that priors could be constructed in a manner that produces biased results. Therefore, some standardization of priors for Bayesian reanalysis of clinical trials may be desirable for the critical care community. In this Critical Care Perspective, we discuss both frequentist and Bayesian approaches to clinical trial analysis, introduce a framework that researchers can use to select priors for a Bayesian reanalysis, and demonstrate how to apply our proposal by conducting a novel Bayesian trial reanalysis.

Lung Ultrasonography in the Monitoring of Intraoperative Recruitment Maneuvers

Introduction: Postoperative respiratory failure is a serious problem in patients who undergo general anesthesia. Approximately 90% of mechanically ventilated patients during the surgery may develop atelectasis that leads to perioperative complications. Aim: The aim of this study is to determine whether it is possible to optimize recruitment maneuvers with the use of chest ultrasonography, thus limiting the risk of respiratory complications in patients who undergo general anesthesia. Methodology: The method of incremental increases in positive end-expiratory pressure (PEEP) values with simultaneous continuous ultrasound assessments was employed in mechanically ventilated patients. Results: The study group comprised 100 patients. The employed method allowed for atelectasis reduction in 91.9% of patients. The PEEP necessary to reverse areas of atelectasis averaged 17cmH₂O, with an average peak pressure of 29cmH₂O. The average PEEP that prevented repeat atelectasis was 9cmH₂O. A significant improvement in lung compliance and saturation was obtained. Conclusions: Ultrasound-guided recruitment maneuvers facilitate the patient-based adjustment of the process. Consequently, the reduction in ventilation pressures necessary to aerate intraoperative atelectasis is possible, with the simultaneous reduction in the risk of procedure-related complications.

Accelerated versus standard initiation of renal replacement therapy for critically ill patients with acute kidney injury: a systematic review and meta-analysis of RCT studies

BACKGROUND

Acute kidney injury (AKI) is a common yet possibly fatal complication among critically ill patients in intensive care units (ICU). Although renal replacement therapy (RRT) is an important supportive management for severe AKI patients, the optimal timing of RRT initiation for these patients is still unclear.

METHODS

In this systematic review, we searched all relevant randomized controlled trials (RCTs) that directly compared accelerated with standard initiation of RRT from PUBMED, MEDLINE, EMBASE, and Cnki.net published prior to July, 20, 2020. We extracted study characteristics and outcomes of being free of dialysis, dialysis dependence and mortality. We rated the certainty of evidence according to Cochrane methods and the GRADE approach.

RESULTS

We identified 56 published relevant studies from 1071 screened abstracts. Ten RCTs with 4753 critically ill AKI patients in intensive care unit (ICU) were included in this meta-analysis. In our study, accelerated and standard RRT group were not associated with all-cause mortality (log odds-ratio [OR]: - 0.04, 95% confidence intervals [CI] - 0.16 to 0.07, p = 0.46) and free of dialysis (log OR: - 0.03, 95% CI - 0.14 to 0.09, p = 0.65). In the subgroup analyses, accelerated RRT group was significantly associated with lower risk of all-cause mortality in the surgical ICU and for those who received continuous renal replacement therapy (CRRT). In addition, patients in these two subgroups had higher chances of being eventually dialysis-free. However, accelerated initiation of RRT augmented the risk of dialysis dependence in the subgroups of patients treated with non-CRRT modality and whose Sequential Organ Failure Assessment (SOFA) score were more than 11.

CONCLUSIONS

In this meta-analysis, critically ill patients with severe AKI would benefit from accelerated RRT initiation regarding all-cause mortality and being eventually free of dialysis only if they were surgical ICU patients or if they underwent CRRT treatment. However, the risk of dialysis dependence was increased in the accelerated RRT group when those patients used non-CRRT modality or had high SOFA scores. All the literatures reviewed in this study were highly heterogeneous and potentially subject to biases. Trial registration CRD42020201466, Sep 07, 2020. https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=201466 .

Emergency Department Management of Severe Hypoxemic Respiratory Failure in Adults With COVID-19

Background

While emergency physicians are familiar with the management of hypoxemic respiratory failure, management of mechanical ventilation and advanced therapies for oxygenation in the emergency department have become essential during the coronavirus disease 2019 (COVID-19) pandemic.

Objective

We review the current evidence on hypoxemia in COVID-19 and place it in the context of known evidence-based management of hypoxemic respiratory failure in the emergency department.

Discussion

COVID-19 causes mortality primarily through the development of acute respiratory distress syndrome (ARDS), with hypoxemia arising from shunt, a mismatch of ventilation and perfusion. Management of patients developing ARDS should focus on mitigating derecruitment and avoiding volutrauma or barotrauma.

Conclusions

High flow nasal cannula and noninvasive positive pressure ventilation have a more limited role in COVID-19 because of the risk of aerosolization and minimal benefit in severe cases, but can be considered. Stable patients who can tolerate repositioning should be placed in a prone position while awake. Once intubated, patients should be managed with ventilation strategies appropriate for ARDS, including targeting lung-protective volumes and low pressures. Increasing positive end-expiratory pressure can be beneficial. Inhaled pulmonary vasodilators do not decrease mortality but may be given to improve refractory hypoxemia. Prone positioning of intubated patients is associated with a mortality reduction in ARDS and can be considered for patients with persistent hypoxemia. Neuromuscular blockade should also be administered in patients who remain dyssynchronous with the ventilator despite adequate sedation. Finally, patients with refractory severe hypoxemic respiratory failure in COVID-19 should be considered for venovenous extracorporeal membrane oxygenation.

Effects of higher PEEP and recruitment manoeuvres on mortality in patients with ARDS: a systematic review, meta-analysis, meta-regression and trial sequential analysis of randomized controlled trials

Purpose

In patients with acute respiratory distress syndrome (ARDS), lung recruitment could be maximised with the use of recruitment manoeuvres (RM) or applying a positive end-expiratory pressure (PEEP) higher than what is necessary to maintain minimal adequate oxygenation. We aimed to determine whether ventilation strategies using higher PEEP and/or RMs could decrease mortality in patients with ARDS.

Methods

We searched MEDLINE, EMBASE and CENTRAL from 1996 to December 2019, included randomized controlled trials comparing ventilation with higher PEEP and/or RMs to strategies with lower PEEP and no RMs in patients with ARDS. We computed pooled estimates with a DerSimonian-Laird mixed-effects model, assessing mortality and incidence of barotrauma, population characteristics, physiologic variables and ventilator settings. We performed a trial sequential analysis (TSA) and a meta-regression.

Results

Excluding two studies that used tidal volume (V_T) reduction as co-intervention, we included 3870 patients from 10 trials using higher PEEP alone (n = 3), combined with RMs (n = 6) or RMs alone (n = 1). We did not observe differences in mortality (relative risk, RR 0.96, 95% confidence interval, CI [0.84–1.09], p = 0.50) nor in incidence of barotrauma (RR 1.22, 95% CI [0.93–1.61], p = 0.16). In the meta-regression, the PEEP difference between intervention and control group at day 1 and the use of RMs were not associated with increased risk of barotrauma. The TSA reached the required information size for mortality (n = 2928), and the z-line surpassed the futility boundary.

Conclusions

At low V_T, the routine use of higher PEEP and/or RMs did not reduce mortality in unselected patients with ARDS.

Trial registration

PROSPERO CRD42017082035.

[Specific treatment of acute lung failure]

Due to a high heterogeneity and dynamic changes in the course of acute respiratory distress syndrome (ARDS), intensive care physicians are faced with extraordinary challenges. While the current definition, pathophysiology and differential diagnoses were previously addressed in this journal, this article focuses on some specific and individualized treatment options. Ventilation treatment with limitation of tidal volumes and pressure amplitudes has been shown to be advantageous with respect to mortality. Nevertheless, because of the multifactorial etiology of ARDS in the context of individual circumstances, this strategy needs to be adjusted to each patient's needs. In recent years it has become increasingly evident that prone positioning, early spontaneous breathing and early mobilization improve the course of the disease. Therefore, an individualized treatment should consider these issues and take the characteristics of the patient and the specific disease progression into account.

Protective ventilation from ICU to operating room: state of art and new horizons

The prevention of ventilator-associated lung injury (VALI) and postoperative pulmonary complications (PPC) is of paramount importance for improving outcomes both in the operating room and in the intensive care unit (ICU). Protective respiratory support includes a wide spectrum of interventions to decrease pulmonary stress-strain injuries. The motto 'low tidal volume for all' should become routine, both during major surgery and in the ICU, while application of a high positive end-expiratory pressure (PEEP) strategy and of alveolar recruitment maneuvers requires a personalized approach and requires further investigation. Patient self-inflicted lung injury is an important type of VALI, which should be diagnosed and mitigated at the early stage, during restoration of spontaneous breathing. This narrative review highlights the strategies used for protective positive pressure ventilation. The emerging concepts of damaging energy and power, as well as pathways to personalization of the respiratory settings, are discussed in detail. In the future, individualized approaches to protective ventilation may involve multiple respiratory settings extending beyond low tidal volume and PEEP, implemented in parallel with quantifying the risk of VALI and PPC.

Maximal Recruitment Open Lung Ventilation in Acute Respiratory Distress Syndrome (PHARLAP). A Phase II, Multicenter Randomized Controlled Clinical Trial

Rationale: Open lung ventilation strategies have been recommended in patients with acute respiratory distress syndrome (ARDS).Objectives: To determine whether a maximal lung recruitment strategy reduces ventilator-free days in patients with ARDS.Methods: A phase II, multicenter randomized controlled trial in adults with moderate to severe ARDS. Patients received maximal lung recruitment, titrated positive end expiratory pressure and further Vt limitation, or control "protective" ventilation.Measurements and Main Results: The primary outcome was ventilator-free days at Day 28. Secondary outcomes included mortality, barotrauma, new use of hypoxemic adjuvant therapies, and ICU and hospital stay. Enrollment halted October 2, 2017, after publication of ART (Alveolar Recruitment for Acute Respiratory Distress Syndrome Trial), when 115 of a planned 340 patients had been randomized (57% male; mean age, 53.6 yr). At 28 days after randomization, there was no difference between the maximal lung recruitment and control ventilation strategies in ventilator-free days (median, 16 d [interquartile range (IQR), 0-21 d], n = 57, vs. 14.5 d [IQR, 0-21.5 d], n = 56; P = 0.95), mortality (24.6% [n = 14/56] vs. 26.8% [n = 15/56]; P = 0.79), or the rate of barotrauma (5.2% [n = 3/57] vs. 10.7% [n = 6/56]; P = 0.32). However, the intervention group showed reduced use of new hypoxemic adjuvant therapies (i.e., inhaled nitric oxide, extracorporeal membrane oxygenation, prone; median change from baseline 0 [IQR, 0-1] vs. 1 [IQR, 0-1]; P = 0.004) and increased rates of new cardiac arrhythmia (n = 17 [29%] vs. n = 7 [13%]; P = 0.03).Conclusions: Compared with control ventilation, maximal lung recruitment did not reduce the duration of ventilation-free days or mortality and was associated with increased cardiovascular adverse events but lower use of hypoxemic adjuvant therapies.Clinical trial registered with www.clinicaltrials.gov (NCT01667146).

Effect of lung recruitment maneuver on oxygenation, physiological parameters and mortality in acute respiratory distress syndrome patients: a systematic review and meta-analysis

PURPOSE

Among acute respiratory distress syndrome (ARDS) patients in intensive care units, the efficacy of lung recruitment maneuver (LRM) use is uncertain taking into account the most recent randomized controlled trials (RCTs). We aimed to estimate the effect of LRMs on mortality from ARDS.

METHODS

In this systematic review and meta-analysis, we searched for RCTs comparing mechanical ventilation with and without LRMs in adults with ARDS. We generated pooled relative risks (RR), mean difference, performed trial-sequential-analysis and cumulative meta-analysis. The primary outcome was 28-day mortality. The secondary outcomes were oxygenation evaluated by PaO₂/FiO₂ ratio, rate of rescue therapy and rate of hemodynamic compromise.

RESULTS

In 14 RCTs including 3185 patients, LRMs were not associated with reduced 28-day mortality (RR = 0.92, 95% confidence interval (95% CI) 0.82-1.04, P = 0.21), compared to no-LRM. Trial-sequential-analysis showed that the required information size has been accrued. PaO₂/FiO₂ ratio was significantly higher in the LRMs group in comparison to the no-LRM group (mean difference = 47.6 mmHg, 95% CI 33.4-61.8, P < 0.001). LRMs were associated with a decreased rate of rescue therapy (RR = 0.69 95% CI 0.56-0.84, P < 0.001), and an increased rate of hemodynamic compromise (RR = 1.19, 95% CI 1.06-1.33, P = 0.002), compared to no-LRM group. Using cumulative meta-analysis, a significant change for effect on mortality was observed after 2017.

CONCLUSIONS

The results suggest that in ARDS patients, systematic use of LRMs does not significantly improve 28-day mortality. However, LRM use was associated with positive effects such as an oxygenation improvement and a less frequent use of rescue therapy. Nevertheless, LRM use was associated with negative effects such as hemodynamic impairment.

Extracorporeal membrane oxygenation as rescue therapy for severe hypoxemic respiratory failure

Extracorporeal membrane oxygenation (ECMO) has been used for more than 50 years as salvage therapy for patients with severe cardiopulmonary failure refractory to conventional treatment. ECMO was first used in the 1960s to treat hypoxemic respiratory failure in newborns. On the basis of its success in that population, ECMO began to be used in the early 1970s to treat adult hypoxemic respiratory failure. However, outcomes for adults were, somewhat perplexingly, quite poor. By the 1980s, use of ECMO for severe hypoxemia was rare outside of the pediatric population. ECMO technology, however, continued to evolve and improve. Multiple case reports and small series describing ECMO use as rescue for adults with severe hypoxemia from various lung pathologies have appeared in the literature over the past three decades. Adult respiratory distress syndrome (ARDS) is often the final common pathway of various pathologies affecting adults and causing hypoxemic respiratory failure. It is prevalent in intensive care units throughout the world and has, since it was first described in 1967, carried a high mortality. No specific therapy for ARDS has been found, and current care is supportive, primarily by mechanical ventilation. Results from recent randomized controlled trials, however, suggest that ECMO may have a place in the treatment of these patients. This article reviews these studies and recommends adding severe ARDS to the list of established indications for ECMO in patients with hypoxemic respiratory failure.

Recruitment manoeuvres for adults with acute respiratory distress syndrome receiving mechanical ventilation: a systematic review and meta-analysis

PURPOSE

To determine if recruitment manoeuvres (RMs) would decrease 28-day mortality of patients with acute respiratory distress syndrome (ARDS) compared with standard care.

MATERIALS AND METHODS

Relevant randomized controlled trials (RCTs) published prior to April 26, 2018 were systematically searched. The primary outcome was mortality. The secondary outcomes were oxygenation, barotrauma or pneumothorax, the need for rescue therapies. Data were pooled using the random effects model. And the quality of evidence was assessed by the GRADE system.

RESULTS

Of 3180 identified studies, 15 were eligibly included in our analysis (N = 2755 participants). In the primary outcome, RMs were not associated with reducing 28-day mortality (RR 0.90; 95% CI 0.74-1.09), ICU mortality (RR 0.92; 95% CI 0.74-1.1), and the in-hospital mortaliy (RR 1.02; 95% CI 0.93-1.12). In the secondary outcomes, RMs could improve oxygenation (MD 37.85; 95% CI 11.08-64.61), the rates of barotrauma (RR 1.42; 95% CI 0.83-2.42) and the need for rescue therapies (RR 0.69; 95% CI 0.42-1.12) did not show any difference in the ARDS patients with RMs.

CONCLUSIONS

Earlier meta-analyses found decreased mortality with RMs, in the contrary, our results indicate that RMs could improve oxygenation without detrimental effects, but it does not appear to reduce mortality.

The Acute Respiratory Distress Syndrome: Diagnosis and Management

Acute respiratory distress syndrome (ARDS) is characterized by a new acute onset of hypoxemia secondary to a pulmonary edema of non-cardiogenic origin, bilateral lung opacities and reduction in respiratory system compliance after an insult direct or indirect to lungs. Its first description was in 1970s, and then several shared definitions tried to describe this clinical entity; the last one, known as Berlin definition, brought an improvement in predictive ability for mortality.

In the present chapter, the diagnostic workup of the syndrome will be presented with particular attention to microbiological investigations which represent a milestone in the diagnostic process and to imaging techniques such as CT scan and lung ultrasound.

Despite the treatment is mainly based on supportive strategies, attention should be applied to assure adequate respiratory gas exchange while minimizing the risk of ventilator-induced lung injury (VILI) onset. Therefore will be described several therapeutic approaches to ARDS, including noninvasive mechanical ventilation (NIMV), high-flow nasal cannulas (HFNC) and invasive ventilation with particular emphasis to risks and benefits of mechanical ventilation, PEEP optimization and lung protective ventilation strategies. Rescue techniques, such as permissive hypercapnia, prone positioning, neuromuscular blockade, inhaled vasodilators, corticosteroids, recruitment maneuvers and extracorporeal life support, will also be reviewed.

Finally, the chapter will deal with the mechanical ventilation weaning process with particular emphasis on extrapulmonary factors such as neurologic, diaphragmatic or cardiovascular alterations which can lead to weaning failure.

Mechanical Ventilation and Extracorporeal Membrane Oxygena tion in Acute Respiratory Insufficiency

BACKGROUND

Mechanical ventilation is life-saving for patients with acute respiratory insufficiency. In a German prevalence study, 13.6% of patients in intensive care units received mechanical ventilation for more than 12 hours; 20% of these patients received mechanical ventilation as treatment for acute respiratory distress syndrome (ARDS). The new S3 guideline is the first to contain recommendations for the entire process of treatment in these groups of patients (indications, ventilation modes/parameters, ac- companying measures, treatments for refractory impairment of gas exchange, weaning, and follow-up care).

METHODS

This guideline was developed according to the GRADE methods. Pertinent publications were identified by a systematic search of the literature, the quality of the evidence was evaluated, a risk/benefit assessment was conducted, and recommendations were issued by interdisciplinary consensus.

RESULTS

Mechanical ventilation is recommended as primary treatment for patients with severe ARDS. In other patient groups, non-in- vasive ventilation can lower mortality. If mechanical ventilation is needed, ventilation modes allowing spontaneous breathing seem beneficial (quality of evidence [QoE]: very low). Protective ventilation (high positive end-expiratory pressure, low tidal volume, limited peak pressure) improve the survival of ARDS patients (QoE: high). If a severe impairment of gas exchange is present, prone posi- tioning lessens mortality (QoE: high). Veno-venous extracorporeal membrane oxygenation (vvECMO) has not unequivocally been shown to improve survival. Early mobilization and weaning protocols can shorten the duration of ventilation (QoE: moderate).

CONCLUSION

Recommendations for patients undergoing mechanical ventilation include lung-protective ventilation, early sponta- neous breathing and mobilization, weaning protocols, and, for those with severe impairment of gas exchange, prone positioning. It is further recommended that patients with ARDS and refractory impairment of gas exchange should be transferred to an ARDS/ECMO center, where extracorporeal methods should be applied only after application of all other therapeutic options.

Beyond Low Tidal Volume Ventilation: Treatment Adjuncts for Severe Respiratory Failure in Acute Respiratory Distress Syndrome

OBJECTIVES

Despite decades of research, the acute respiratory distress syndrome remains associated with significant morbidity and mortality. This Concise Definitive Review provides a practical and evidence-based summary of treatments in addition to low tidal volume ventilation and their role in the management of severe respiratory failure in acute respiratory distress syndrome.

DATA SOURCES

We searched the PubMed database for clinical trials, observational studies, and review articles describing treatment adjuncts in acute respiratory distress syndrome patients, including high positive end-expiratory pressure strategies, recruitment maneuvers, high-frequency oscillatory ventilation, neuromuscular blockade, prone positioning, inhaled pulmonary vasodilators, extracorporeal membrane oxygenation, glucocorticoids, and renal replacement therapy.

STUDY SELECTION AND DATA EXTRACTION

Results were reviewed by the primary author in depth. Disputed findings and conclusions were then reviewed with the other authors until consensus was achieved.

DATA SYNTHESIS

Severe respiratory failure in acute respiratory distress syndrome may present with refractory hypoxemia, severe respiratory acidosis, or elevated plateau airway pressures despite lung-protective ventilation according to acute respiratory distress syndrome Network protocol. For severe hypoxemia, first-line treatment adjuncts include high positive end-expiratory pressure strategies, recruitment maneuvers, neuromuscular blockade, and prone positioning. For refractory acidosis, we recommend initial modest liberalization of tidal volumes, followed by neuromuscular blockade and prone positioning. For elevated plateau airway pressures, we suggest first decreasing tidal volumes, followed by neuromuscular blockade, modification of positive end-expiratory pressure, and prone positioning. Therapies such as inhaled pulmonary vasodilators, glucocorticoids, and renal replacement therapy have significantly less evidence in favor of their use and should be considered second line. Extracorporeal membrane oxygenation may be life-saving in selected patients with severe acute respiratory distress syndrome but should be used only when other alternatives have been applied.

CONCLUSIONS

Severe respiratory failure in acute respiratory distress syndrome often necessitates the use of treatment adjuncts. Evidence-based application of these therapies in acute respiratory distress syndrome remains a significant challenge. However, a rational stepwise approach with frequent monitoring for improvement or harm can be achieved.

Driving-pressure-independent protective effects of open lung approach against experimental acute respiratory distress syndrome

Background

The open lung approach (OLA) reportedly has lung-protective effects against acute respiratory distress syndrome (ARDS). Recently, lowering of the driving pressure (ΔP), rather than improvement in lung aeration per se, has come to be considered as the primary lung-protective mechanism of OLA. However, the driving pressure-independent protective effects of OLA have never been evaluated in experimental studies. We here evaluated whether OLA shows protective effects against experimental ARDS even when the ΔP is not lowered.

Methods

Lipopolysaccharide was intratracheally administered to rats to establish experimental ARDS. After 24 h, rats were mechanically ventilated and randomly allocated to the OLA or control group. In the OLA group, 5 cmH₂O positive end-expiratory pressure (PEEP) and recruitment maneuver (RM) were applied. Neither PEEP nor RM was applied to the rats in the control group. Dynamic ΔP was kept at 15 cmH₂O in both groups. After 6 h of mechanical ventilation, rats in both groups received RM to inflate reversible atelectasis of the lungs. Arterial blood gas analysis, lung computed tomography, histological evaluation, and comprehensive biochemical analysis were performed.

Results

OLA significantly improved lung aeration, arterial oxygenation, and gas exchange. Even after RM in both groups, the differences in these parameters between the two groups persisted, indicating that the atelectasis-induced respiratory dysfunction observed in the control group is not an easily reversible functional problem. Lung histological damage was severe in the dorsal dependent area in both groups, but was attenuated by OLA. White blood cell counts, protein concentrations, and tissue injury markers in the broncho-alveolar lavage fluid (BALF) were higher in the control than in the OLA group. Furthermore, levels of CXCL-7, a platelet-derived chemokine, were higher in the BALF from the control group, indicating that OLA protects the lungs by suppressing platelet activation.

Conclusions

OLA shows protective effects against experimental ARDS, even when the ΔP is not decreased. In addition to reducing ΔP, maintaining lung aeration seems to be important for lung protection in ARDS.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2154-2) contains supplementary material, which is available to authorized users.

Practice of diagnosis and management of acute respiratory distress syndrome in mainland China: a cross-sectional study

Background

Although acute respiratory distress syndrome (ARDS) has been recognized for more than 50 years, limited information exists about the incidence and management of ARDS in mainland China. To evaluate the potential for improvement in management of patients with ARDS, this study was designed to describe the incidence and management of ARDS in mainland China.

Methods

, 2012) of all patients who fulfilled the Berlin or American European Consensus Conference (AECC) definition of ARDS in 20 intensive care units, with data collection related to the management of ARDS, patient characteristics and outcomes.

Results

was 90%. A recruitment maneuver was performed in 35.5% of the patients, and 8.7% of patients with severe ARDS received prone position. Overall hospital mortality was 34.0%. Hospital mortality was 21.8% for mild, 31.1% for moderate, and 60.0% for patients with severe ARDS (P=0.004).

Conclusions

Despite general acceptance of low Vt and limited Pplat, high driving pressure, low PEEP and low use of adjunctive measures may still be a concern in mainland China, especially in patients with severe ARDS.

Trial Registration

2012.

Effect of lung protective ventilation on coronary heart disease patients undergoing lung cancer resection

Background

Mechanical ventilation, especially large tidal volume (Vt) one-lung ventilation (OLV), can cause ventilator-induced lung injury (VILI) that can stimulate cytokines. Meanwhile, cytokines are considered very important factor influencing coronary heart disease (CHD) patient prognosis. So minimization of pulmonary inflammatory responses by reduction of cytokine levels for CHD undergoing lung resection during OLV should be a priority. Because previous studies have demonstrated that lung-protective ventilation (LPV) reduced lung inflammation, this ventilation approach was studied for CHD patients undergoing lung resection here to evaluate the effects of LPV on pulmonary inflammatory responses.

Methods

This is a single center, randomized controlled trial. Primary endpoint of the study are plasma concentrations of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-10 and C-reactive protein (CRP). Secondary endpoints include respiratory variables and hemodynamic variables. 60 CHD patients undergoing video-assisted thoracoscopic lung resection were randomly divided into conventional ventilation group [10 mL/kg Vt and 0 cmH₂O positive end-expiratory pressure (PEEP), C group] and protective ventilation group (6 mL/kg Vt and 6 cmH₂O PEEP, P group; 30 patients/group). Hemodynamic variables, peak inspiratory pressure (Ppeak), dynamic compliance (Cdyn), arterial oxygen tension (PaO₂) and arterial carbon dioxide tension (PaCO₂) were recorded as test data at three time points: T1-endotracheal intubation for two-lung ventilation (TLV) when breathing and hemodynamics were stable; T2-after TLV was substituted with OLV when breathing and hemodynamics were stable; T3-OLV was substituted with TLV at the end of surgery when breathing and hemodynamics were stable. The concentrations of TNF-α, IL-6, IL-10 and CRP in patients' blood in both groups at the very beginning of OLV (beginning of OLV) and the end moment of the surgery (end of surgery) were measured.

Results

The P group exhibited greater PaO₂, higher Cdyn and lower Ppeak than the C group at T2, T3 (P<0.05). At the end moment of the surgery, although the P group tended to exhibit higher TNF-α and IL-10 values than the C group, the differences did not reach statistical significance(P=0.0817, P=0.0635). Compared with C group at the end moment of the surgery, IL-6 and CRP were lower in P group, the differences were statistically significant (P=0.0093, P=0.0005). There were no significant differences in hemodynamic variables between the two groups (P>0.05).

Conclusions

LPV can effectively reduce the airway pressure, improve Cdyn and PaO₂, reduce concentrations of IL-6 and CRP during lung resection of CHD patients.Trial registration: The trial was registered in the Chinese Clinical Trial Registry.

Lung Recruitment Maneuvers for Adult Patients with Acute Respiratory Distress Syndrome. A Systematic Review and Meta-Analysis

RATIONALE

In patients with acute respiratory distress syndrome (ARDS), lung recruitment maneuvers (LRMs) may prevent ventilator-induced lung injury and improve survival.

OBJECTIVES

To summarize the current evidence in support of the use of LRMs in adult patients with ARDS and to inform the recently published American Thoracic Society/European Society of Intensive Care Medicine/Society of Critical Care Medicine clinical practice guideline on mechanical ventilation in ARDS.

METHODS

We conducted a systematic review and meta-analysis of randomized trials comparing mechanical ventilation strategies with and without LRMs. Eligible trials were identified from among previously published systematic reviews and an updated literature search. Data on 28-day mortality, oxygenation, adverse events, and use of rescue therapy were collected, and results were pooled using random effects models weighted by inverse variance. Strength of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation methodology.

RESULTS

We screened 430 citations and previous systematic reviews and found six trials eligible for inclusion (n = 1,423 patients in total). The type of LRM varied widely between trials, and five of the trials involved a cointervention with a higher positive end-expiratory pressure (PEEP) ventilation strategy. Risk of bias was deemed high in one trial. In the primary analysis, the only trial without a cointervention showed that LRMs were associated with reduced mortality (one trial; risk ratio [RR], 0.62; 95% confidence interval [CI], 0.39-0.98; evidence grade = low). Meta-analysis of all six trials also suggested a significant mortality reduction (six trials; RR, 0.81; 95% CI, 0.69-0.95; evidence grade = moderate), and the use of a higher PEEP cointervention did not significantly modify the mortality effect (P = 0.27 for heterogeneity). LRMs were also associated with improved oxygenation after 24 hours (six trials; mean increase, 52 mm Hg; 95% CI, 23-81 mm Hg) and less frequent requirement for rescue therapy (three trials; RR, 0.65; 95% CI, 0.45-0.94). LRMs were not associated with an increased rate of barotrauma (four trials; RR, 0.84; 95% CI, 0.46-1.55). The rate of hemodynamic compromise was not significantly increased with LRMs (three trials; RR, 1.30; 95% CI, 0.92-1.78).

CONCLUSIONS

Randomized trials suggest that LRMs in combination with a higher PEEP ventilation strategy reduce mortality, but confidence in this finding is limited. Further trials are required to confirm benefit from LRMs in adults with ARDS.

Statistical analysis plan for the Alveolar Recruitment for Acute Respiratory Distress Syndrome Trial (ART). A randomized controlled trial

BACKGROUND

The Alveolar Recruitment for Acute Respiratory Distress Syndrome Trial (ART) is an international multicenter randomized pragmatic controlled trial with allocation concealment involving 120 intensive care units in Brazil, Argentina, Colombia, Italy, Poland, Portugal, Malaysia, Spain, and Uruguay. The primary objective of ART is to determine whether maximum stepwise alveolar recruitment associated with PEEP titration, adjusted according to the static compliance of the respiratory system (ART strategy), is able to increase 28-day survival in patients with acute respiratory distress syndrome compared to conventional treatment (ARDSNet strategy).

OBJECTIVE

To describe the data management process and statistical analysis plan.

METHODS

The statistical analysis plan was designed by the trial executive committee and reviewed and approved by the trial steering committee. We provide an overview of the trial design with a special focus on describing the primary (28-day survival) and secondary outcomes. We describe our data management process, data monitoring committee, interim analyses, and sample size calculation. We describe our planned statistical analyses for primary and secondary outcomes as well as pre-specified subgroup analyses. We also provide details for presenting results, including mock tables for baseline characteristics, adherence to the protocol and effect on clinical outcomes.

CONCLUSION

According to best trial practice, we report our statistical analysis plan and data management plan prior to locking the database and beginning analyses. We anticipate that this document will prevent analysis bias and enhance the utility of the reported results.

TRIAL REGISTRATION

ClinicalTrials.gov number, NCT01374022.

Mechanical Ventilation in Sepsis: A Reappraisal

Sepsis is the main cause of close to 70% of all cases of acute respiratory distress syndromes (ARDS). In addition, sepsis increases susceptibility to ventilator-induced lung injury. Therefore, the development of a ventilatory strategy that can achieve adequate oxygenation without injuring the lungs is highly sought after for patients with acute infection and represents an important therapeutic window to improve patient care. Suboptimal ventilatory settings cannot only harm the lung, but may also contribute to the cascade of organ failure in sepsis due to organ crosstalk.Despite the prominent role of sepsis as a cause for lung injury, most of the studies that addressed mechanical ventilation strategies in ARDS did not specifically assess sepsis-related ARDS patients. Consequently, most of the recommendations regarding mechanical ventilation in sepsis patients are derived from ARDS trials that included multiple clinical diagnoses. While there have been important improvements in general ventilatory management that should apply to all critically ill patients, sepsis-related lung injury might still have particularities that could influence bedside management.After revisiting the interplay between sepsis and ventilation-induced lung injury, this review will reappraise the evidence for the major components of the lung protective ventilation strategy, emphasizing the particularities of sepsis-related acute lung injury.

Recruitment manoeuvres in anaesthesia: How many more excuses are there not to use them?

Pulmonary recruitment manoeuvres (RM) are intended to reopen collapsed lung areas. RMs are present in nature as a physiological mechanism to get a newborn to open their lungs for the first time at birth, and we also use them, in our usual anaesthesiological clinical practice, after induction or during general anaesthesia when a patient is desaturated. However, there is much confusion in clinical practice regarding their safety, the best way to perform them, when to do them, in which patients they are indicated, and in those where they are totally contraindicated. There are important differences between RM in the patient with adult respiratory distress syndrome, and in a healthy patient during general anaesthesia. Our intention is to review, from a clinical and practical point of view, the use of RM, specifically in anaesthesia.

Time-sensitive therapeutics

Much of what we now do in Critical Care carries an air of urgency, a pressing need to discover and act, with priorities biased toward a reactive response. However, efficacy often depends not simply upon what we do, but rather on whether, when, and how persistently we intervene. The practice of medicine is based upon diagnosis, integration of multiple sources of information, keen judgment, and appropriate intervention. Timing may not be everything, as the well-known adage suggests, but in the intensive care unit (ICU) timing issues clearly deserve more attention than they are currently given. Successfully or not, the patient is continually attempting to adapt and re-adjust to acute illness, and this adaptive  process takes time. Knowing that much of what we do carries potential for unintended harm as well as benefit, the trick is to decide whether the patient is winning or losing the adaptive struggle and whether we can help. Costs of modern ICU care is enormous and the trend line shows no encouraging sign of moderation. To sharpen our effectiveness, reduce hazard, and pare cost we must learn to time our interventions, help the patient adapt, and at times withhold treatment rather than jump in on the impulse to rescue and/or to alter the natural course of disease. Indeed, much of the progress made in our discipline has resulted both from timely intervention when called for and avoidance or moderation of hazardous treatments when not. Time-sensitive ICU therapeutics requires awareness of trends in key parameters, respect for adaptive chronobiology, level-headed evaluation of the need to intervene, and awareness of the costs of disrupting a potentially constructive natural response to illness.

Effect of Lung Recruitment and Titrated Positive End-Expiratory Pressure (PEEP) vs Low PEEP on Mortality in Patients With Acute Respiratory Distress Syndrome: A Randomized Clinical Trial

IMPORTANCE

The effects of recruitment maneuvers and positive end-expiratory pressure (PEEP) titration on clinical outcomes in patients with acute respiratory distress syndrome (ARDS) remain uncertain.

OBJECTIVE

To determine if lung recruitment associated with PEEP titration according to the best respiratory-system compliance decreases 28-day mortality of patients with moderate to severe ARDS compared with a conventional low-PEEP strategy.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter, randomized trial conducted at 120 intensive care units (ICUs) from 9 countries from November 17, 2011, through April 25, 2017, enrolling adults with moderate to severe ARDS.

INTERVENTIONS

An experimental strategy with a lung recruitment maneuver and PEEP titration according to the best respiratory-system compliance (n = 501; experimental group) or a control strategy of low PEEP (n = 509). All patients received volume-assist control mode until weaning.

MAIN OUTCOMES AND MEASURES

The primary outcome was all-cause mortality until 28 days. Secondary outcomes were length of ICU and hospital stay; ventilator-free days through day 28; pneumothorax requiring drainage within 7 days; barotrauma within 7 days; and ICU, in-hospital, and 6-month mortality.

RESULTS

A total of 1010 patients (37.5% female; mean [SD] age, 50.9 [17.4] years) were enrolled and followed up. At 28 days, 277 of 501 patients (55.3%) in the experimental group and 251 of 509 patients (49.3%) in the control group had died (hazard ratio [HR], 1.20; 95% CI, 1.01 to 1.42; P = .041). Compared with the control group, the experimental group strategy increased 6-month mortality (65.3% vs 59.9%; HR, 1.18; 95% CI, 1.01 to 1.38; P = .04), decreased the number of mean ventilator-free days (5.3 vs 6.4; difference, -1.1; 95% CI, -2.1 to -0.1; P = .03), increased the risk of pneumothorax requiring drainage (3.2% vs 1.2%; difference, 2.0%; 95% CI, 0.0% to 4.0%; P = .03), and the risk of barotrauma (5.6% vs 1.6%; difference, 4.0%; 95% CI, 1.5% to 6.5%; P = .001). There were no significant differences in the length of ICU stay, length of hospital stay, ICU mortality, and in-hospital mortality.

CONCLUSIONS AND RELEVANCE

In patients with moderate to severe ARDS, a strategy with lung recruitment and titrated PEEP compared with low PEEP increased 28-day all-cause mortality. These findings do not support the routine use of lung recruitment maneuver and PEEP titration in these patients.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01374022.

[Extreme obesity-particular aspect of invasive and noninvasive ventilation]

The obesity rate is increasing worldwide and the percentage of obese patients in the intensive care unit (ICU) is rising concomitantly. Ventilatory support strategies in obese patients must take into account the altered pathophysiological conditions. Unfortunately, prospective randomized multicenter trials on this subject are lacking. Therefore, current strategies are based on the individual experiences of ICU physicians and single-center studies. Noninvasive ventilation (NIV) in critically ill patients with acute respiratory failure and obesity hypoventilation syndrome (OHS) is an efficient treatment option and should be provided as early as possible is an effort to avoid intubation. Patient positioning is also crucial: half-sitting positions (>45°) improve lung compliance and functional residual capacity in patients with respiratory failure. Transpulmonary pressure measurements or the Acute Respiratory Distress Syndrome (ARDS) Network tables may help to adjust the optimal positive end-expiratory pressure (PEEP). The tidal volume should be adapted to the ideal and not the actual bodyweight (V_t = 6 ml/kg of ideal bodyweight) to avoid lung damage and (additional) right ventricular stress. Under particular conditions, inspiratory pressures >30 cmH₂O may be tolerated for a limited duration. Early tracheostomy combined with termination/reduction of sedation and relaxation is controversy discussed in the literature as a therapeutic option during invasive ventilation of morbidly obese patients. However, data on early tracheotomy in obese respiratory failure patients are rare and this should be regarded as an individual treatment attempt only. In cases of refractory lung failure, venovenous extracorporeal membrane oxygenation (vv-ECMO) is an option despite anatomic changes in morbid obesity.

Mechanical Ventilation: State of the Art

Mechanical ventilation is the most used short-term life support technique worldwide and is applied daily for a diverse spectrum of indications, from scheduled surgical procedures to acute organ failure. This state-of-the-art review provides an update on the basic physiology of respiratory mechanics, the working principles, and the main ventilatory settings, as well as the potential complications of mechanical ventilation. Specific ventilatory approaches in particular situations such as acute respiratory distress syndrome and chronic obstructive pulmonary disease are detailed along with protective ventilation in patients with normal lungs. We also highlight recent data on patient-ventilator dyssynchrony, humidified high-flow oxygen through nasal cannula, extracorporeal life support, and the weaning phase. Finally, we discuss the future of mechanical ventilation, addressing avenues for improvement.

Quality indicators in intensive care medicine for Germany - third edition 2017

Quality improvement in medicine is depending on measurement of relevant quality indicators. The quality indicators for intensive care medicine of the German Interdisciplinary Society of Intensive Care Medicine (DIVI) from the year 2013 underwent a scheduled evaluation after three years. There were major changes in several indicators but also some indicators were changed only minimally. The focus on treatment processes like ward rounds, management of analgesia and sedation, mechanical ventilation and weaning, as well as the number of 10 indicators were not changed. Most topics remained except for early mobilization which was introduced instead of hypothermia following resuscitation. Infection prevention was added as an outcome indicator. These quality indicators are used in the peer review in intensive care, a method endorsed by the DIVI. A validity period of three years is planned for the quality indicators.

Update in Management of Severe Hypoxemic Respiratory Failure

Mortality related to severe-moderate and severe ARDS remains high. We searched the literature to update this topic. We defined severe hypoxemic respiratory failure as Pao₂/Fio₂ < 150 mm Hg (ie, severe-moderate and severe ARDS). For these patients, we support setting the ventilator to a tidal volume of 4 to 8 mL/kg predicted body weight (PBW), with plateau pressure (Pplat) ≤ 30 cm H₂O, and initial positive end-expiratory pressure (PEEP) of 10 to 12 cm H₂O. To promote alveolar recruitment, we propose increasing PEEP in increments of 2 to 3 cm provided that Pplat remains ≤ 30 cm H₂O and driving pressure does not increase. A fluid-restricted strategy is recommended, and nonrespiratory causes of hypoxemia should be considered. For patients who remain hypoxemic after PEEP optimization, neuromuscular blockade and prone positioning should be considered. Profound refractory hypoxemia (Pao₂/Fio₂ < 80 mm Hg) after PEEP titration is an indication to consider extracorporeal life support. This may necessitate early transfer to a center with expertise in these techniques. Inhaled vasodilators and nontraditional ventilator modes may improve oxygenation, but evidence for improved outcomes is weak.

Early Versus Late Initiation of Renal Replacement Therapy in Critically Ill Patients: Systematic Review and Meta-Analysis

OBJECTIVE

Early initiation of renal replacement therapy (RRT) effect on survival and renal recovery of critically ill patients is still uncertain. We aimed to systematically review current evidence comparing outcomes of early versus late initiation of RRT in critically ill patients.

METHODS

We searched the Medline (via Pubmed), LILACS, Science Direct, and CENTRAL databases from inception until November 2016 for randomized clinical trials (RCTs) or observational studies comparing early versus late initiation of RRT in critically ill patients. The primary outcome was mortality. Duration of mechanical ventilation, intensive care unit (ICU) length of stay (LOS), hospital LOS, and renal function recovery were secondary outcomes. Meta-analysis and trial sequential analysis (TSA) were used for the primary outcome.

RESULTS

Sixty-two studies were retrieved and analyzed, including 11 RCTs. There was no difference in mortality between early and late initiation of RRT among RCTs (odds ratio [OR] = 0.78; 95% confidence interval [CI]: 0.52-1.19; I² = 63.1%). Trial sequential analysis of mortality across all RCTs achieved futility boundaries at both 1% and 5% type I error rates, although a subgroup analysis of studies including only acute kidney injury patients was not conclusive. There was also no difference in time on mechanical ventilation, ICU and hospital LOS, or renal recovery among studies. Early initiation of RRT was associated with reduced mortality among prospective (OR = 0.69; 95% CI: 0.49-0.96; I² = 85.9%) and retrospective (OR = 0.61; 95% CI: 0.41-0.92; I² = 90.9%) observational studies, both with substantial heterogeneity. However, subgroup analysis excluding low-quality observational studies did not achieve statistical significance.

CONCLUSION

Pooled analysis of randomized trials indicates early initiation of RRT is not associated with lower mortality rates. The potential benefit of reduced mortality associated with early initiation of RRT was limited to low-quality observational studies.

Mechanical ventilation in the acute respiratory distress syndrome

The management of the acute respiratory distress syndrome (ARDS) patient is fundamental to the field of intensive care medicine, and it presents unique challenges owing to the specialized mechanical ventilation techniques that such patients require. ARDS is a highly lethal disease, and there is compelling evidence that mechanical ventilation itself, if applied in an injurious fashion, can be a contributor to ARDS mortality. Therefore, it is imperative for any clinician central to the care of ARDS patients to understand the fundamental framework that underpins the approach to mechanical ventilation in this special scenario. The current review summarizes the major components of the mechanical ventilation strategy as it applies to ARDS.

[The old man and the I sea U : Essay on faith, fate and evidence - after the manner of Hemingway]

Robert Bartlett, emeritus Professor of surgery at the University of Michigan in Ann Arbor, USA, transformed classical works of world literature (Charles Dickens: A Christmas Carol, Lewis Carroll: Alice in Wonderland) into teaching aids for advanced training in intensive care medicine. He recently turned his hand to the well-known work of Ernest Hemingway: the Nobel Prize winning novel The Old Man and the Sea. Subsequent to Robert Bartlett's essay this article provides background information and comments on the current problems in modern intensive care medicine addressed in his essay.