Pressure-controlled versus volume-controlled ventilation for acute respiratory failure due to acute lung injury (ALI) or acute respiratory distress syndrome (ARDS)

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.

Primary graft dysfunction following lung transplantation: From pathogenesis to future frontiers

Lung transplantation is the treatment of choice for patients with end-stage lung disease. Currently, just under 5000 lung transplants are performed worldwide annually. However, a major scourge leading to 90-d and 1-year mortality remains primary graft dysfunction. It is a spectrum of lung injury ranging from mild to severe depending on the level of hypoxaemia and lung injury post-transplant. This review aims to provide an in-depth analysis of the epidemiology, pathophysiology, risk factors, outcomes, and future frontiers involved in mitigating primary graft dysfunction. The current diagnostic criteria are examined alongside changes from the previous definition. We also highlight the issues surrounding chronic lung allograft dysfunction and identify the novel therapies available for ex-vivo lung perfusion. Although primary graft dysfunction remains a significant contributor to 90-d and 1-year mortality, ongoing research and development abreast with current technological advancements have shed some light on the issue in pursuit of future diagnostic and therapeutic tools.

The Effect of Switching from Volume-Controlled to Pressure-Controlled Ventilation on Respiratory Distress and Asynchrony Index Improvement among Mechanically Ventilated Adults

Background

It is important to synchrony the time, intensity, and respiratory signal of the phrenic nerve between the patient and the ventilator. This study aimed to evaluate the effect of switching from volume-controlled to pressure-controlled ventilation on respiratory distress and asynchrony index improvement.

Materials and Methods

In this randomized controlled clinical trial, 70 patients admitted to the intensive care unit under mechanical ventilation were included. Asynchronous evaluation was performed by examining the patient and evaluating and analyzing the graphic flow curve and ventilator pressure, which included trigger and flow asynchronous and asynchronous cycling. In the intervention group, the mode of ventilation was switched to PSIMV such that peak inspiratory pressures would be equivalent to positive end-expiratory pressure (PEEP) in the volume-controlled mode. Finally, again at 60, 75, and 90 min, information about the ventilator and the patient's symptoms, and arterial carbon dioxide levels were sent by arterial gas sample. The asynchronous index was also recorded in both groups.

Results

This study showed that the mean of variables such as height, ideal body weight, tidal volume, set rate; Sense, FiO₂, PEEP did not differ significantly between the two groups. The mean of asynchrony was significantly reduced in both control group (16.51 ± 3.35-14.51 ± 2.90; P < 0.001) and intervention group (18.26 ± 6.13-13.32 ± 5.53; P < 0.001).

Conclusion

Regardless of the type and severity of the disease, switching the ventilation mode from volume-controlled to pressure-controlled can improve patient adaptation to the ventilator, especially in cases with frequent asynchrony.

Using real-time visualization system for data-driven decision support to achieve lung protective strategy: a retrospective observational study

Background

Although lung protective strategy and adjunctive intervention are associated with improved survival in patients with acute respiratory distress syndrome (ARDS), the implementation of effective therapies remains low. This study aimed to evaluate whether the use of business intelligence (BI) for real-time data visualization is associated with an improvement in lung protective strategy and adjunctive therapy.

Methods

A retrospective observational cohort study was conducted on patients with ARDS admitted between September 2020 and June 2021 at two intensive care units (ICUs) of a tertiary referral hospital in Taiwan. BI was imported for data visualization and integration to assist in clinical decision in one of the ICUs. The primary outcomes were the implementation of low tidal volume ventilation (defined as tidal volume/predicted body weight ≤ 8 mL/kg) within 24 h from ARDS onset. The secondary outcomes included ICU and hospital mortality rates.

Results

Among the 1201 patients admitted to the ICUs during the study period, 148 (12.3%) fulfilled the ARDS criteria, with 86 patients in the BI-assisted group and 62 patients in the standard-of-care (SOC) group. Disease severity was similar between the two groups. The application of low tidal volume ventilation strategy was significantly improved in the BI-assisted group compared with that in the SOC group (79.1% vs. 61.3%, p = 0.018). Despite their ARDS and disease severity, the BI-assisted group tended to achieve low tidal volume ventilation. The ICU and hospital mortality were lower in the BI-assisted group.

Conclusions

The use of real-time visualization system for data-driven decision support was associated with significantly improved compliance to low tidal volume ventilation strategy, which enhanced the outcomes of patients with ARDS in the ICU.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04091-0.

ARDS Clinical Practice Guideline 2021

Background

The joint committee of the Japanese Society of Intensive Care Medicine/Japanese Respiratory Society/Japanese Society of Respiratory Care Medicine on ARDS Clinical Practice Guideline has created and released the ARDS Clinical Practice Guideline 2021.

Methods

The 2016 edition of the Clinical Practice Guideline covered clinical questions (CQs) that targeted only adults, but the present guideline includes 15 CQs for children in addition to 46 CQs for adults. As with the previous edition, we used a systematic review method with the Grading of Recommendations Assessment Development and Evaluation (GRADE) system as well as a degree of recommendation determination method. We also conducted systematic reviews that used meta-analyses of diagnostic accuracy and network meta-analyses as a new method.

Results

Recommendations for adult patients with ARDS are described: we suggest against using serum C-reactive protein and procalcitonin levels to identify bacterial pneumonia as the underlying disease (GRADE 2D); we recommend limiting tidal volume to 4–8 mL/kg for mechanical ventilation (GRADE 1D); we recommend against managements targeting an excessively low SpO₂ (PaO₂) (GRADE 2D); we suggest against using transpulmonary pressure as a routine basis in positive end-expiratory pressure settings (GRADE 2B); we suggest implementing extracorporeal membrane oxygenation for those with severe ARDS (GRADE 2B); we suggest against using high-dose steroids (GRADE 2C); and we recommend using low-dose steroids (GRADE 1B). The recommendations for pediatric patients with ARDS are as follows: we suggest against using non-invasive respiratory support (non-invasive positive pressure ventilation/high-flow nasal cannula oxygen therapy) (GRADE 2D), we suggest placing pediatric patients with moderate ARDS in the prone position (GRADE 2D), we suggest against routinely implementing NO inhalation therapy (GRADE 2C), and we suggest against implementing daily sedation interruption for pediatric patients with respiratory failure (GRADE 2D).

Conclusions

This article is a translated summary of the full version of the ARDS Clinical Practice Guideline 2021 published in Japanese (URL: https://www.jsicm.org/publication/guideline.html). The original text, which was written for Japanese healthcare professionals, may include different perspectives from healthcare professionals of other countries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40560-022-00615-6.

Clinical Efficacy of Budesonide/Glycopyrronium Bromide/Formoterol in the Treatment of Patients with Acute Respiratory Distress Syndrome and Its Effect on Inflammatory Factors

Objective

To examine the clinical efficacy of budesonide/glycopyrronium bromide/formoterol (Breztri Aerosphere) as an adjunct to acute respiratory distress syndrome (ARDS).

Methods

A prospective study enrolled 120 patients with pulmonary endogenous ARDS admitted to the Department of Critical Care Medicine at the Fourth Hospital of Baotou from January 2017 to January 2020, and all enrollments were assigned (1 : 1) to receive conventional treatment (control group) or Breztri Aerosphere (study group).

Results

Breztri Aerosphere was associated with a significantly higher total efficacy versus conventional treatment. Breztri Aerosphere resulted in significantly lower acute physiology and chronic health evaluation scoring system (APACHE II) scores and Murray lung injury scores versus conventional treatment. Both groups saw an increase in the partial pressure of carbon dioxide (PCO2), partial pressure of oxygen (PO2), and oxygen saturation (SaO2) after treatment, with higher levels seen in patients given Breztri Aerosphere. After treatment, systemic vascular resistance (SVR) in both groups rose markedly, with greater elevation witnessed in the study group. The patients given Breztri Aerosphere showed significantly lower levels of pulmonary vascular resistance (PVR), mean pulmonary arterial pressure (MAPA), pulmonary artery wedge pressure (PAWP), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-α), and procalcitonin (PCT) versus those receiving conventional treatment. The patients experienced shorter mechanical ventilation time and intensive care unit (ICU) time after treatment of Breztri Aerosphere versus conventional treatment.

Conclusion

Adjuvant therapy with Breztri Aerosphere in ARDS can significantly lower APACHE II scores and Murray lung injury scores, improve blood gas indexes and pulmonary circulation function indexes, and shorten mechanical ventilation time and ICU time, which may be attributed to its improvement of organism inflammation status and reduction of inflammatory factors.

“The role of a negative pressure ventilator coupled with oxygen helmet against COVID-19: a review”

Background

The coronavirus (SARS-COV-2) pandemic has provoked the global healthcare industry by potentially affecting more than 20 14 million people across the globe, causing lasting damage to the lungs, notably pneumonia, ARDS (acute respiratory distress 15 syndrome), and sepsis with the rapid spread of infection. To aid the functioning of the lungs and to maintain the blood oxygen 16 saturation (SpO₂) in coronavirus patients, ventilator assistance is required.

Materials and methods

The main purpose of this article is to outline the need 17 for the introduction of a non-invasive negative pressure ventilator (NINPV) as a promising alternative to positive pressure 18 ventilator (PPV) by elucidating the cons of non-invasive ventilators in clinical conditions like ARDS. Another motive is to 19 profoundly diminish the rate of infection spread by the employment of oxygen helmets, instead of endotracheal intubation in 20 invasive positive pressure ventilator (IPPV) or non-invasive positive pressure ventilator (NIPPV) like face masks and high-flow 21 nasal cannula (HFNC).

Result and conclusion

The integration of oxygen helmet with NPV would result in a number of notable facets including the 22 degree of comfort delivered to patients who are exposed to various ventilator-induced lung injuries (VILI) in the forms of 23 atelectasis, barotrauma, etc. Likewise, preventing the aerosol-generating procedures (AGP) diminishes the rate of nosocomial 24 infections and providing a better environment to both the patients and the healthcare professionals.

Post‑treatment with propofol inhibits inflammatory response in LPS‑induced alveolar type II epithelial cells

Over-inflammation and severe lung injury are major causes of morbidity and mortality in patients with coronavirus disease 2019 (COVID-19). With the COVID-19 pandemic, an increasing number of patients with preexisting lung injury and inflammation are undergoing surgery or artificial ventilation under sedation in intensive care units, where 2,6-diisopropylphenol (propofol) is a commonly used drug for sedation. The aim of the present study was to investigate whether post-inflammation treatment with propofol protects epithelial type II cells against inflammation in an in vitro model of inflammation. The A549 cell line, characterised as epithelial type II cells, were exposed to lipopolysaccharide (LPS) for 2 h and subsequently treated with different concentrations of propofol (0, 10, 25 or 50 µM) for 3 h. Western blot and reverse transcription-quantitative PCR analyses were used to detect the protein and mRNA expression levels, respectively, of CD14 and Toll-like receptor 4 (TLR4). Immunofluorescence staining was used to detect the in situ CD14 and TLR4 expression in epithelial type II cells. Tumor necrosis factor (TNF)-α production was also examined using ELISA. LPS significantly increased the expression of CD14 and TLR4, as well as the secretion of TNF-α. Post-treatment with 25 and 50 µM propofol of the LPS-treated cells significantly decreased CD14 and TLR4 expression, as well as TNF-α secretion, compared with the cells treated with LPS only, indicating that post-treatment with propofol alleviated inflammation and this effect was dose-dependent. The present study suggested that treatment with propofol after LPS administration has a protective effect on epithelial type II cells.

Translational Role of Rodent Models to Study Ventilator-Induced Lung Injury

Mechanical ventilation is an important part of medical care in intensive care units and operating rooms to support respiration. While it is a critical component of medical care, it is well known that mechanical ventilation itself can be injurious to the lungs. Despite a large number of clinical and preclinical studies that have been done so far, there still exists a gap of knowledge regarding how to ventilate patients mechanically without increasing lung injury. Here, we will review what we have learned so far from preclinical and clinical studies and consider how to use preclinical models of ventilation-induced lung injury that better recapitulate the clinical scenarios.

A Melanin-like Nanoenzyme for Acute Lung Injury Therapy via Suppressing Oxidative and Endoplasmic Reticulum Stress Response

Nanoenzyme-mediated catalytic activity is emerging as a novel strategy for reactive oxygen species (ROS) scavenging in acute lung injury (ALI) treatment. However, one of the main hurdles for these metal-containing nanoenzymes is their potential toxicity and single therapeutic mechanism. Herein, we uncovered a melanin-like nanoparticles derived from the self-polymerization of 1,8-dihydroxynaphthalene (PDH nanoparticles), showing a significant anti-inflammation therapeutic effect on ALI mice. The prepared PDH nanoparticles rich in phenol groups could not only act as radical scavengers to alleviate oxidative stress but could also chelate calcium overload to suppress the endoplasmic reticulum stress response. As revealed by the therapeutic effect in vivo, PDH nanoparticles significantly prohibited neutrophil infiltration and the secretion of proinflammatory cytokines (TNF-α and IL-6), thus improving the inflammatory cascade in the ALI model. Above all, our work provides an effective anti-inflammatory nanoplatform by using the inherent capability of melanin-like nanoenzymes, proposing the potential application prospects of these melanin-like nanoparticles for acute inflammation-induced injury treatment.

Ventilator-induced lung-injury in mouse models: Is there a trap?

Ventilator-induced lung injury (VILI) is a serious acute injury to the lung tissue that can develop during mechanical ventilation of patients. Due to the mechanical strain of ventilation, damage can occur in the bronchiolar and alveolar epithelium resulting in a cascade of events that may be fatal to the patients. Patients requiring mechanical ventilation are often critically ill, which limits the possibility of obtaining patient samples, making VILI research challenging. In vitro models are very important for VILI research, but the complexity of the cellular interactions in multi-organ animals, necessitates in vivo studies where the mouse model is a common choice. However, the settings and duration of ventilation used to create VILI in mice vary greatly, causing uncertainty in interpretation and comparison of results. This review examines approaches to induce VILI in mouse models for the last 10 years, to our best knowledge, summarizing methods and key parameters presented across the studies. The results imply that a more standardized approach is warranted.

Particle flow rate from the airways as fingerprint diagnostics in mechanical ventilation in the intensive care unit: a randomised controlled study

Introduction

Mechanical ventilation can be monitored by analysing particles in exhaled air as measured by particle flow rate (PFR). This could be a potential method of detecting ventilator-induced lung injury (VILI) before changes in conventional parameters can be detected. The aim of this study was to investigate PFR during different ventilation modes in patients without lung pathology.

Method

A prospective study was conducted on patients on mechanical ventilation in the cardiothoracic intensive care unit (ICU). A PExA 2.0 device was connected to the expiratory limb on the ventilator for continuous measurement of PFR in 30 patients randomised to either volume-controlled ventilation (VCV) or pressure-controlled ventilation (PCV) for 30 min including a recruitment manoeuvre. PFR measurements were continued as the patients were transitioned to pressure-regulated volume control (PRVC) and then pressure support ventilation (PSV) until extubation.

Results

PRVC resulted in significantly lower PFR, while those on PSV had the highest PFR. The distribution of particles differed significantly between the different ventilation modes.

Conclusions

Measuring PFR is safe after cardiac surgery in the ICU and may constitute a novel method of continuously monitoring the small airways in real time. A low PFR during mechanical ventilation may correlate to a gentle ventilation strategy. PFR increases as the patient transitions from controlled mechanical ventilation to autonomous breathing, which most likely occurs as recruitment by the diaphragm opens up more distal airways. Different ventilation modes resulted in unique particle patterns and could be used as a fingerprint for the different ventilation modes.

Particle flow rate (PFR) from the airways may be used to continuously monitor the small airways in real time. A low PFR during mechanical controlled ventilation is likely to correspond to a protective ventilation.https://bit.ly/2RSkIqL

BD, Salazar Gutierrez G, Gómez González JF, Echeverry Piedrahita DR, Galvis JC, Aguirre-Flórez M. Mechanical ventilation in SARS-CoV-2 patients: state of art

COVID-19-associated infection leads to a pathology of yet unknown clinical behavior, confronting the clinician with various challenges. An extensive search was conducted based on review articles on SARS-CoV-2 infection and studies including mechanical ventilation management strategies in order to complete this narrative review. Evidenced-based treatment for SARS-CoV2 infection is still in the works. We have some tools from our knowledge from past experiences indicating that a step-wise management approach should be used, without neglecting other joint therapeutic measures for improved clinical outcomes of a condition with a high mortality. The current recommendations indicate that patients with severe acute respiratory failure due to SARS-CoV-2 should be managed with protective mechanical ventilation measures. No strong evidence is yet available on the individualization of mechanical ventilation therapy according to phenotypes.

The novel Mechanical Ventilator Milano for the COVID-19 pandemic

This paper presents the Mechanical Ventilator Milano (MVM), a novel intensive therapy mechanical ventilator designed for rapid, large-scale, low-cost production for the COVID-19 pandemic. Free of moving mechanical parts and requiring only a source of compressed oxygen and medical air to operate, the MVM is designed to support the long-term invasive ventilation often required for COVID-19 patients and operates in pressure-regulated ventilation modes, which minimize the risk of furthering lung trauma. The MVM was extensively tested against ISO standards in the laboratory using a breathing simulator, with good agreement between input and measured breathing parameters and performing correctly in response to fault conditions and stability tests. The MVM has obtained Emergency Use Authorization by U.S. Food and Drug Administration (FDA) for use in healthcare settings during the COVID-19 pandemic and Health Canada Medical Device Authorization for Importation or Sale, under Interim Order for Use in Relation to COVID-19. Following these certifications, mass production is ongoing and distribution is under way in several countries. The MVM was designed, tested, prepared for certification, and mass produced in the space of a few months by a unique collaboration of respiratory healthcare professionals and experimental physicists, working with industrial partners, and is an excellent ventilator candidate for this pandemic anywhere in the world.

Mechanical Ventilation Management During Mechanical Chest Compressions

Ventilation during chest compressions can lead to an increase in peak inspiratory pressure. High inspiratory pressure can raise the risk of injury to the respiratory system and make it challenging to deliver the required tidal volume. The utilization of mechanical devices for chest compression has exacerbated this challenge. The aim of this narrative review was to summarize the different mechanical ventilation strategies applied during mechanical cardiopulmonary resuscitation (CPR). To this end, we searched the PubMed and BioMed Central databases from inception to January 2020, using the search terms "mechanical ventilation," "cardiac arrest," "cardiopulmonary resuscitation," "mechanical cardiopulmonary resuscitation," and their related terms. We included all studies (human clinical or animal-based research studies, as well as studies using simulation models) to explore the various ventilation settings during mechanical CPR. We identified 842 relevant articles on PubMed and 397 on BioMed Central; a total of 38 papers were judged to be specifically related to the subject of this review. Of this sample, 17 studies were conducted on animal models, 6 considered a simulated scenario, 13 were clinical studies (5 of which were retrospective), and 2 studies constituted literature review articles. The main finding arising from the assessment of these publications is that a high [Formula: see text] must be guaranteed during CPR. Low-grade evidence suggests turning off inspiratory triggering and applying PEEP ≥ 5 cm H₂O. The analysis also revealed that many uncertainties persist regarding the ideal choice of ventilation mode, tidal volume, the ventilation rate setting, and the inspiratory:expiratory ratio. None of the current international guidelines indicate the "best" mechanical ventilation strategy to apply during mechanical CPR. We propose an operating algorithm worthy of future discussion and study. Future studies specifically addressing the topics covered in this review are required.

Pulmonary barotrauma in mechanically ventilated coronavirus disease 2019 patients: A case series

Background

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may result in hypoxic respiratory failure necessitating mechanical ventilation. Barotrauma is a well-documented complication of mechanical ventilation.

Objective

To describe the presentation, characteristics, and management of mechanically ventilated patients with COVID-19 who developed barotrauma.

Methods

Retrospective case series study of 13 adult, mechanically ventilated, laboratory-confirmed COVID-19 positive patients admitted between 3/15/2020 and 4/14/2020 to a community hospital in New York City. Patient demographics, clinical course, ventilatory parameters, and radiographic results were obtained from electronic medical records. Barotrauma was defined as pneumomediastinum, subcutaneous emphysema, and or pneumothorax on chest X-ray. Descriptive analyses and Mann-Whitney U test were performed, where appropriate.

Results

Of the 574 COVID-19 positive patients, 139 (24.2%) needed mechanical ventilation and 13 (9.4%) of those developed barotrauma. Majority of patients were Black race (92.3%), older than age 65 (56.8%), male (69.2%), and had comorbidities (76.9%). Most common presenting symptoms were cough (84.6%) and dyspnea (76.9%). Barotrauma presentations included 3/13 pneumothoraces and pneumomediastinum, 12/13 pneumomediastinum and subcutaneous emphysema, and 1/13 pneumothorax alone. The average days on ventilator was 3.4, average positive expiratory-end pressure 15.5 cmH2O, dynamic compliance 33.8 mL/cmH2O, and P/F ratio 165. Interventions were 4/13 chest tubes and 2/13 pigtail catheters.

Conclusions

Barotrauma is a common complication of mechanical ventilation of COVID-19 patients. Despite high ventilatory pressures, tension pneumothorax is rare and barotrauma could potentially be managed conservatively. Further studies are needed to evaluate the indication and outcome of thoracostomies and conservative management.

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Pulmonary barotrauma is a risk of mechanical ventilation.

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Many patients with COVID-19 pneumonia require mechanical ventilation.

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Patients with COVID-19 pneumonia are susceptible to pulmonary barotrauma.

The Gut Microbiota and Respiratory Diseases: New Evidence

Human body surfaces, such as the skin, intestines, and respiratory and urogenital tracts, are colonized by a large number of microorganisms, including bacteria, fungi, and viruses, with the gut being the most densely and extensively colonized organ. The microbiome plays an essential role in immune system development and tissue homeostasis. Gut microbiota dysbiosis not only modulates the immune responses of the gastrointestinal (GI) tract but also impacts the immunity of distal organs, such as the lung, further affecting lung health and respiratory diseases. Here, we review the recent evidence of the correlations and underlying mechanisms of the relationship between the gut microbiota and common respiratory diseases, including asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), lung cancer, and respiratory infection, and probiotic development as a therapeutic intervention for these diseases.

Initial emergency department mechanical ventilation strategies for COVID-19 hypoxemic respiratory failure and ARDS

INTRODUCTION

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging viral pathogen that causes the novel coronavirus disease of 2019 (COVID-19) and may result in hypoxemic respiratory failure necessitating invasive mechanical ventilation in the most severe cases.

OBJECTIVE

This narrative review provides evidence-based recommendations for the treatment of COVID-19 related respiratory failure requiring invasive mechanical ventilation.

DISCUSSION

In severe cases, COVID-19 leads to hypoxemic respiratory failure that may meet criteria for acute respiratory distress syndrome (ARDS). The mainstay of treatment for ARDS includes a lung protective ventilation strategy with low tidal volumes (4-8 mL/kg predicted body weight), adequate positive end-expiratory pressure (PEEP), and maintaining a plateau pressure of < 30 cm H₂O. While further COVID-19 specific studies are needed, current management should focus on supportive care, preventing further lung injury from mechanical ventilation, and treating the underlying cause.

CONCLUSIONS

This review provides evidence-based recommendations for the treatment of COVID-19 related respiratory failure requiring invasive mechanical ventilation.

Intubation and Ventilation amid the COVID-19 Outbreak: Wuhan's Experience

The COVID-19 outbreak has led to 80,409 diagnosed cases and 3,012 deaths in mainland China based on the data released on March 4, 2020. Approximately 3.2% of patients with COVID-19 required intubation and invasive ventilation at some point in the disease course. Providing best practices regarding intubation and ventilation for an overwhelming number of patients with COVID-19 amid an enhanced risk of cross-infection is a daunting undertaking. The authors presented the experience of caring for the critically ill patients with COVID-19 in Wuhan. It is extremely important to follow strict self-protection precautions. Timely, but not premature, intubation is crucial to counter a progressively enlarging oxygen debt despite high-flow oxygen therapy and bilevel positive airway pressure ventilation. Thorough preparation, satisfactory preoxygenation, modified rapid sequence induction, and rapid intubation using a video laryngoscope are widely used intubation strategies in Wuhan. Lung-protective ventilation, prone position ventilation, and adequate sedation and analgesia are essential components of ventilation management.

Intubation and Ventilation amid the COVID-19 Outbreak: Wuhan's Experience

The COVID-19 outbreak has led to 80,409 diagnosed cases and 3,012 deaths in mainland China based on the data released on March 4, 2020. Approximately 3.2% of patients with COVID-19 required intubation and invasive ventilation at some point in the disease course. Providing best practices regarding intubation and ventilation for an overwhelming number of patients with COVID-19 amid an enhanced risk of cross-infection is a daunting undertaking. The authors presented the experience of caring for the critically ill patients with COVID-19 in Wuhan. It is extremely important to follow strict self-protection precautions. Timely, but not premature, intubation is crucial to counter a progressively enlarging oxygen debt despite high-flow oxygen therapy and bilevel positive airway pressure ventilation. Thorough preparation, satisfactory preoxygenation, modified rapid sequence induction, and rapid intubation using a video laryngoscope are widely used intubation strategies in Wuhan. Lung-protective ventilation, prone position ventilation, and adequate sedation and analgesia are essential components of ventilation management.

Intraoperative ventilator settings and their association with postoperative pulmonary complications in neurosurgical patients: post-hoc analysis of LAS VEGAS study

BACKGROUND

Limited information is available regarding intraoperative ventilator settings and the incidence of postoperative pulmonary complications (PPCs) in patients undergoing neurosurgical procedures. The aim of this post-hoc analysis of the 'Multicentre Local ASsessment of VEntilatory management during General Anaesthesia for Surgery' (LAS VEGAS) study was to examine the ventilator settings of patients undergoing neurosurgical procedures, and to explore the association between perioperative variables and the development of PPCs in neurosurgical patients.

METHODS

Post-hoc analysis of LAS VEGAS study, restricted to patients undergoing neurosurgery. Patients were stratified into groups based on the type of surgery (brain and spine), the occurrence of PPCs and the assess respiratory risk in surgical patients in Catalonia (ARISCAT) score risk for PPCs.

RESULTS

Seven hundred eighty-four patients were included in the analysis; 408 patients (52%) underwent spine surgery and 376 patients (48%) brain surgery. Median tidal volume (V_T) was 8 ml [Interquartile Range, IQR = 7.3-9] per predicted body weight; median positive end-expiratory pressure (PEEP) was 5 [3 to 5] cmH₂0. Planned recruitment manoeuvres were used in the 6.9% of patients. No differences in ventilator settings were found among the sub-groups. PPCs occurred in 81 patients (10.3%). Duration of anaesthesia (odds ratio, 1.295 [95% confidence interval 1.067 to 1.572]; p = 0.009) and higher age for the brain group (odds ratio, 0.000 [0.000 to 0.189]; p = 0.031), but not intraoperative ventilator settings were independently associated with development of PPCs.

CONCLUSIONS

Neurosurgical patients are ventilated with low V_T and low PEEP, while recruitment manoeuvres are seldom applied. Intraoperative ventilator settings are not associated with PPCs.

Randomized Feasibility Trial of a Low Tidal Volume-Airway Pressure Release Ventilation Protocol Compared With Traditional Airway Pressure Release Ventilation and Volume Control Ventilation Protocols

Supplemental Digital Content is available in the text.

Objectives:

Low tidal volume (= tidal volume ≤ 6 mL/kg, predicted body weight) ventilation using volume control benefits patients with acute respiratory distress syndrome. Airway pressure release ventilation is an alternative to low tidal volume-volume control ventilation, but the release breaths generated are variable and can exceed tidal volume breaths of low tidal volume-volume control. We evaluate the application of a low tidal volume-compatible airway pressure release ventilation protocol that manages release volumes on both clinical and feasibility endpoints.

Design:

We designed a prospective randomized trial in patients with acute hypoxemic respiratory failure. We randomized patients to low tidal volume-volume control, low tidal volume-airway pressure release ventilation, and traditional airway pressure release ventilation with a planned enrollment of 246 patients. The study was stopped early because of low enrollment and inability to consistently achieve tidal volumes less than 6.5 mL/kg in the low tidal volume-airway pressure release ventilation arm. Although the primary clinical study endpoint was Pao₂/Fio₂ on study day 3, we highlight the feasibility outcomes related to tidal volumes in both arms.

Setting:

Four Intermountain Healthcare tertiary ICUs.

Patients:

Adult ICU patients with hypoxemic respiratory failure anticipated to require prolonged mechanical ventilation.

Interventions:

Low tidal volume-volume control, airway pressure release ventilation, and low tidal volume-airway pressure release ventilation.

Measurements and Main Results:

We observed wide variability and higher tidal (release for airway pressure release ventilation) volumes in both airway pressure release ventilation (8.6 mL/kg; 95% CI, 7.8–9.6) and low tidal volume-airway pressure release ventilation (8.0; 95% CI, 7.3–8.9) than volume control (6.8; 95% CI, 6.2–7.5; p = 0.005) with no difference between airway pressure release ventilation and low tidal volume-airway pressure release ventilation (p = 0.58). Recognizing the limitations of small sample size, we observed no difference in 52 patients in day 3 Pao₂/ Fio₂ (p = 0.92). We also observed no significant difference between arms in sedation, vasoactive medications, or occurrence of pneumothorax.

Conclusions:

Airway pressure release ventilation resulted in release volumes often exceeding 12 mL/kg despite a protocol designed to target low tidal volume ventilation. Current airway pressure release ventilation protocols are unable to achieve consistent and reproducible delivery of low tidal volume ventilation goals. A large-scale efficacy trial of low tidal volume-airway pressure release ventilation is not feasible at this time in the absence of an explicit, generalizable, and reproducible low tidal volume-airway pressure release ventilation protocol.

Clinical Guideline for Treating Acute Respiratory Insufficiency with Invasive Ventilation and Extracorporeal Membrane Oxygenation: Evidence-Based Recommendations for Choosing Modes and Setting Parameters of Mechanical Ventilation

For patients with acute respiratory insufficiency, mechanical ("invasive") ventilation is a fundamental therapeutic measure to ensure sufficient gas exchange. Despite decades of strong research efforts, central questions on mechanical ventilation therapy are still answered incompletely. Therefore, many different ventilation modes and settings have been used in daily clinical practice without scientifically sound bases. At the same time, implementation of the few evidence-based therapeutic concepts (e.g., "lung protective ventilation") into clinical practice is still insufficient. The aim of our guideline project "Mechanical ventilation and extracorporeal gas exchange in acute respiratory insufficiency" was to develop an evidence-based decision aid for treating patients with and on mechanical ventilation. It covers the whole pathway of invasively ventilated patients (including indications of mechanical ventilation, ventilator settings, additional and rescue therapies, and liberation from mechanical ventilation). To assess the quality of scientific evidence and subsequently derive recommendations, we applied the Grading of Recommendations, Assessment, Development and Evaluation method. For the first time, using this globally accepted methodological standard, our guideline contains recommendations on mechanical ventilation therapy not only for acute respiratory distress syndrome patients but also for all types of acute respiratory insufficiency. This review presents the two main chapters of the guideline on choosing the mode of mechanical ventilation and setting its parameters. The guideline group aimed that - by thorough implementation of the recommendations - critical care teams may further improve the quality of care for patients suffering from acute respiratory insufficiency. By identifying relevant gaps of scientific evidence, the guideline group intended to support the development of important research projects.

Perioperative anaesthetic management of patients with or at risk of acute distress respiratory syndrome undergoing emergency surgery

Patients undergoing emergency surgery may present with the acute respiratory distress syndrome (ARDS) or develop this syndrome postoperatively. The incidence of ARDS in the postoperative period is relatively low, but the impact of ARDS on patient outcomes and healthcare costs is relevant Aakre et.al (Mayo Clin Proc 89:181-9, 2014).The development of ARDS as a postoperative pulmonary complication (PPC) is associated with prolonged hospitalisation, longer duration of mechanical ventilation, increased intensive care unit length of stay and high morbidity and mortality Ball et.al (Curr Opin Crit Care 22:379-85, 2016). In order to mitigate the risk of ARDS after surgery, the anaesthetic management and protective mechanical ventilation strategies play an important role. In particular, a careful integration of general anaesthesia with neuraxial or locoregional techniques might promote faster recovery and reduce opioid consumption. In addition, the use of low tidal volume, minimising plateau pressure and titrating a low-moderate PEEP level based on the patient's need can improve outcome and reduce intraoperative adverse events. Moreover, perioperative management of ARDS patients includes specific anaesthesia and ventilator settings, hemodynamic monitoring, moderately restrictive fluid administration and pain control.The aim of this review is to provide an overview and evidence- and opinion-based recommendations concerning the management of patients at risk of and with ARDS who undergo emergency surgical procedures.

Invasive Mechanical Ventilation

Invasive mechanical ventilation is a potentially lifesaving intervention for acutely ill patients. The goal of this review is to provide a concise, clinically focused overview of basic invasive mechanical ventilation for the many clinicians who care for mechanically ventilated patients. Attention is given to how common ventilator modes differ in delivering a mechanical breath, evaluation of respiratory system mechanics, how to approach acute changes in airway pressure, and the diagnosis of auto-positive end-expiratory pressure. Waveform interpretation is emphasized throughout the review.

Pharmacological agents for adults with acute respiratory distress syndrome

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a life-threatening condition caused by direct or indirect injury to the lungs. Despite improvements in clinical management (for example, lung protection strategies), mortality in this patient group is at approximately 40%. This is an update of a previous version of this review, last published in 2004.

OBJECTIVES

To evaluate the effectiveness of pharmacological agents in adults with ARDS on mortality, mechanical ventilation, and fitness to return to work at 12 months.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and CINAHL on 10 December 2018. We searched clinical trials registers and grey literature, and handsearched reference lists of included studies and related reviews.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing pharmacological agents with control (placebo or standard therapy) to treat adults with established ARDS. We excluded trials of nitric oxide, inhaled prostacyclins, partial liquid ventilation, neuromuscular blocking agents, fluid and nutritional interventions and medical oxygen. We excluded studies published earlier than 2000, because of changes to lung protection strategies for people with ARDS since this date.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, extracted data, and assessed risks of bias. We assessed the certainty of evidence with GRADE.

MAIN RESULTS

We included 48 RCTs with 6299 participants who had ARDS; two included only participants with mild ARDS (also called acute lung injury). Most studies included causes of ARDS that were both direct and indirect injuries. We noted differences between studies, for example the time of administration or the size of dose, and because of unclear reporting we were uncertain whether all studies had used equivalent lung protection strategies.We included five types of agents as the primary comparisons in the review: corticosteroids, surfactants, N-acetylcysteine, statins, and beta-agonists. We included 15 additional agents (sivelestat, mesenchymal stem cells, ulinastatin, anisodimine, angiotensin-converting enzyme (ACE) inhibitor, recombinant human ACE2 (palifermin), AP301, granulocyte-macrophage colony stimulating factor (GM-CSF), levosimendan, prostacyclins, lisofylline, ketaconazole, nitroglycerins, L-2-oxothiazolidine-4-carboxylic acid (OTZ), and penehyclidine hydrochloride).We used GRADE to downgrade outcomes for imprecision (because of few studies and few participants), for study limitations (e.g. high risks of bias) and for inconsistency (e.g. differences between study data).Corticosteroids versus placebo or standard therapyCorticosteroids may reduce all-cause mortality within three months by 86 per 1000 patients (with as many as 161 fewer to 19 more deaths); however, the 95% confidence interval (CI) includes the possibility of both increased and reduced deaths (risk ratio (RR) 0.77, 95% CI 0.57 to 1.05; 6 studies, 574 participants; low-certainty evidence). Due to the very low-certainty evidence, we are uncertain whether corticosteroids make little or no difference to late all-cause mortality (later than three months) (RR 0.99, 95% CI 0.64 to 1.52; 1 study, 180 participants), or to the duration of mechanical ventilation (mean difference (MD) -4.30, 95% CI -9.72 to 1.12; 3 studies, 277 participants). We found that ventilator-free days up to day 28 (VFD) may be improved with corticosteroids (MD 4.09, 95% CI 1.74 to 6.44; 4 studies, 494 participants; low-certainty evidence). No studies reported adverse events leading to discontinuation of study medication, or fitness to return to work at 12 months (FTR).Surfactants versus placebo or standard therapyWe are uncertain whether surfactants make little or no difference to early mortality (RR 1.08, 95% CI 0.91 to 1.29; 9 studies, 1338 participants), or whether they reduce late all-cause mortality (RR 1.28, 95% CI 1.01 to 1.61; 1 study, 418 participants). Similarly, we are uncertain whether surfactants reduce the duration of mechanical ventilation (MD -2.50, 95% CI -4.95 to -0.05; 1 study, 16 participants), make little or no difference to VFD (MD -0.39, 95% CI -2.49 to 1.72; 2 studies, 344 participants), or to adverse events leading to discontinuation of study medication (RR 0.50, 95% CI 0.17 to 1.44; 2 studies, 88 participants). We are uncertain of these effects because we assessed them as very low-certainty. No studies reported FTR.N-aceytylcysteine versus placeboWe are uncertain whether N-acetylcysteine makes little or no difference to early mortality, because we assessed this as very low-certainty evidence (RR 0.64, 95% CI 0.32 to 1.30; 1 study, 36 participants). No studies reported late all-cause mortality, duration of mechanical ventilation, VFD, adverse events leading to study drug discontinuation, or FTR.Statins versus placeboStatins probably make little or no difference to early mortality (RR 0.99, 95% CI 0.78 to 1.26; 3 studies, 1344 participants; moderate-certainty evidence) or to VFD (MD 0.40, 95% CI -0.71 to 1.52; 3 studies, 1342 participants; moderate-certainty evidence). Statins may make little or no difference to duration of mechanical ventilation (MD 2.70, 95% CI -3.55 to 8.95; 1 study, 60 participants; low-certainty evidence). We could not include data for adverse events leading to study drug discontinuation in one study because it was unclearly reported. No studies reported late all-cause mortality or FTR.Beta-agonists versus placebo controlBeta-blockers probably slightly increase early mortality by 40 per 1000 patients (with as many as 119 more or 25 fewer deaths); however, the 95% CI includes the possibility of an increase as well as a reduction in mortality (RR 1.14, 95% CI 0.91 to 1.42; 3 studies, 646 participants; moderate-certainty evidence). Due to the very low-certainty evidence, we are uncertain whether beta-agonists increase VFD (MD -2.20, 95% CI -3.68 to -0.71; 3 studies, 646 participants), or make little or no difference to adverse events leading to study drug discontinuation (one study reported little or no difference between groups, and one study reported more events in the beta-agonist group). No studies reported late all-cause mortality, duration of mechanical ventilation, or FTR.

AUTHORS' CONCLUSIONS

We found insufficient evidence to determine with certainty whether corticosteroids, surfactants, N-acetylcysteine, statins, or beta-agonists were effective at reducing mortality in people with ARDS, or duration of mechanical ventilation, or increasing ventilator-free days. Three studies awaiting classification may alter the conclusions of this review. As the potential long-term consequences of ARDS are important to survivors, future research should incorporate a longer follow-up to measure the impacts on quality of life.

Invasive mechanical ventilation in the emergency department

Emergency department (ED) lenght of stay of the patients requiring admission to the intensive care units has increased gradually in recent years. Mechanical ventilation is an integral part of critical care and mechanically ventilated patients have to be managed and monitored by emergency physicians for longer than expected in EDs. This early period of care has significant impact on the outcomes of these patients. Therefore, emergency physicians should have comprehensive knowledge of mechanical ventilation. This review will summarize the current literature of the basic concepts, appropriate clinical applications, monitoring parameters, components and mechanisms of mechanical ventilation in the ED.

Different particle flow patterns from the airways after recruitment manoeuvres using volume-controlled or pressure-controlled ventilation

Objectives

Noninvasive online monitoring of different particle flows from the airways may serve as an additional tool to assess mechanical ventilation. In the present study, we used a customised PExA, an optical particle counter for monitoring particle flow and size distribution in exhaled air, to analyse airway particle flow for three subsequent days. We compared volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) and performed recruitment manoeuvres (RM).

Methods

Six animals were randomised into two groups: half received VCV before PCV and the other half received PCV before VCV. Measurements were taken daily for 1 h in each mode during three subsequent days in six fully anaesthetised domestic pigs. A RM was performed twice daily for 60 s at positive end-expiratory pressure (PEEP) of 10, 4 breaths/min and inspiratory-expiratory ratio (I:E) of 2:1. Measurements were taken for 3 min before the RM, 1 min during the RM and for 3 min after the RM. The particle sizes measured were between 0.48 and 3.37 μm.

Results

A significant stepwise decrease was observed in total particle count from day 1 to day 3, and at the same time, an increase in fluid levels was seen. Comparing VCV to PCV, a significant increase in total particle count was observed on day 2, with the highest particle count occurring during VCV. A significant increase was observed comparing before and after RM on day 1 and 2 but not on day 3. One animal developed ARDS and showed a different particle pattern compared to the other animals.

Conclusions

This study shows the safety and useability of the PExA technique used in conjunction with mechanical ventilation. We detected differences between the ventilation modes VCV and PCV in total particle count without any significant changes in ventilator pressure levels, FiO₂ levels or the animals’ vital parameters. The findings during RM indicate an opening of the small airways, but the effect is short lived. We have also showed that VCV and PCV may affect the lung physiology differently during recruitment manoeuvres. These findings might indicate that this technique may provide more refined information on the impact of mechanical ventilation.

Acute Respiratory Distress Syndrome

Acute Respiratory Distress Syndrome (ARDS) is a well-described disease process that can have numerous underlying causes, is commonly seen in the critical care setting, and is often under-recognized. ARDS is characterized by pulmonary edema with refractory hypoxemia, and was traditionally associated with a high mortality rate. The past few decades have generated many studies examining therapeutic interventions for ARDS; however, there are few Level 1 evidence-based interventions to this day that have been shown to improve mortality and outcomes. Lung protective ventilation remains the most studied and evidence-based intervention for the treatment of ARDS.

Optimal Strategies for Severe Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) occurs in more than 10% of intensive care unit admissions and in nearly 25% of ventilated patients. Mortality remains high at 40%, and, for patients who survive, recovery continues for months or even years. Early recognition and minimizing further lung injury remain essential to successful management of severe ARDS. Advanced treatment strategies, which complement lung protective ventilation, include short-term neuromuscular blockade, prone positioning, and extracorporeal membrane oxygenation. Alternative ventilator strategies include high-frequency ventilation and airway pressure release ventilation. This article reviews these options in patients with severe ARDS.

The intensive care medicine research agenda for airways, invasive and noninvasive mechanical ventilation

In an important sense, support of the respiratory system has been a defining characteristic of intensive care since its inception. The pace of basic and clinical research in this field has escalated over the past two decades, resulting in palpable improvement at the bedside as measured by both efficacy and outcome. As in all medical research, however, novel ideas built upon observations are continually proposed, tested, and either retained or discarded on the basis of the persuasiveness of the evidence. What follows are concise descriptions of the current standards of management practice in respiratory support, the areas of present-day uncertainty, and our suggested agenda for the near future of research aimed at testing current assumptions, probing uncertainties, and solidifying the foundation on which to base our progress to the next level.

Respiratory Considerations Including Airway and Ventilation Issues in Critical Care Obstetric Patients

Critical care management of the obstetric patient can present unique challenges. Parturients who present with respiratory distress can suffer from a multitude of etiologies, and each diagnosis must be pursued as appropriate to the clinical picture. Normal physiologic changes of pregnancy may obscure the presentation and diagnosis, and irrelevant of the cause, pregnancy may complicate the management of hypoxic and hypercarbic respiratory failure in this patient population. In addition to these concerns, both anticipated and unanticipated difficult airway management, including difficulty ventilating and intubating, are more common during pregnancy and may be encountered during endotracheal tube placement.

[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.

Current Concepts of ARDS: A Narrative Review

Acute respiratory distress syndrome (ARDS) is characterized by the acute onset of pulmonary edema of non-cardiogenic origin, along with bilateral pulmonary infiltrates and reduction in respiratory system compliance. The hallmark of the syndrome is refractory hypoxemia. Despite its first description dates back in the late 1970s, a new definition has recently been proposed. However, the definition remains based on clinical characteristic. In the present review, the diagnostic workup and the pathophysiology of the syndrome will be presented. Therapeutic approaches to ARDS, including lung protective ventilation, prone positioning, neuromuscular blockade, inhaled vasodilators, corticosteroids and recruitment manoeuvres will be reviewed. We will underline how a holistic framework of respiratory and hemodynamic support should be provided to patients with ARDS, aiming to ensure adequate gas exchange by promoting lung recruitment while minimizing the risk of ventilator-induced lung injury. To do so, lung recruitability should be considered, as well as the avoidance of lung overstress by monitoring transpulmonary pressure or airway driving pressure. In the most severe cases, neuromuscular blockade, prone positioning, and extra-corporeal life support (alone or in combination) should be taken into account.

Acute respiratory distress syndrome

Acute respiratory distress syndrome presents as hypoxia and bilateral pulmonary infiltrates on chest imaging in the absence of heart failure sufficient to account for this clinical state. Management is largely supportive, and is focused on protective mechanical ventilation and the avoidance of fluid overload. Patients with severe hypoxaemia can be managed with early short-term use of neuromuscular blockade, prone position ventilation, or extracorporeal membrane oxygenation. The use of inhaled nitric oxide is rarely indicated and both β₂ agonists and late corticosteroids should be avoided. Mortality remains at approximately 30%.

Patient Safety: Identifying and Managing Complications of Mechanical Ventilation

Mechanical ventilation is a fundamental aspect of critical care practice to help meet the respiratory needs of critically ill patients. Complications can occur though, as a direct result of being mechanically ventilated, or indirectly because of a secondary process. Preventing, identifying, and managing these complications significantly contribute to the role and responsibilities of critical care nurses in promoting patient safety. This article reviews common ventilator-associated events, including both infectious (eg, ventilator-associated pneumonia) and noninfectious causes (eg, acute respiratory distress syndrome, pulmonary edema, pleural effusion, and atelectasis).

Protective effect of suppressing STAT3 activity in LPS-induced acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are diseases with high mortality. Macrophages and neutrophils are responsible for inflammatory responses in ALI and ARDS, which are characterized by excessive production of proinflammatory mediators in bronchoalveolar lavage fluid (BALF) and plasma. Aberrant activation of the JAK/STAT pathway is critical for persistent inflammation in many conditions such as infection and autoimmunity. Given the importance of the STAT3 transcription factor in activating macrophages and neutrophils and augmenting inflammation, we investigated the therapeutic potential of inhibiting STAT3 activity using the small-molecule STAT3 inhibitor, LLL12. Our results demonstrate that LPS induces STAT3 activation in macrophages in vitro and in CD45⁺CD11b⁺ cells from BALF in the LPS-induced ALI model in vivo. LLL12 treatment inhibits LPS-induced lung inflammation in the ALI model, which is accompanied by suppression of LPS-induced STAT3 activation and an inhibition of macrophage and inflammatory cell infiltration in lung and BALF. LLL12 treatment also suppresses expression of proinflammatory genes including IL-1β, IL-6, TNF-α, iNOS, CCL2, and MHC class II in macrophages and inflammatory cells from BALF and serum as determined by ELISA. Furthermore, hyperactivation of STAT3 in LysMCre-SOCS3^fl/fl mice accelerates the severity of inflammation in the ALI model. Both pre- and post-LPS treatment with LLL12 decrease LPS-induced inflammatory responses in mice with ALI. Importantly, LLL12 treatment attenuates STAT3 phosphorylation in human peripheral blood mononuclear cells induced by plasma from patients with ARDS, which suggests the feasibility of targeting the STAT3 pathway therapeutically for patients with ALI and ARDS.

Propofol attenuated liver transplantation-induced acute lung injury via connexin43 gap junction inhibition

BACKGROUND

Postoperative acute lung injury (ALI) is a severe complication after liver transplantation, which influences patient survival rate obviously. However, its mechanisms are unclear and effective therapies are still lacking. The current study focused on effects of propofol on liver transplantation-induced ALI and whether its underlying mechanism was relative with connexin43 (Cx43) alternation. The authors postulated that endotoxin induced enhancement of Cx43 gap junction (GJ) plays a critical role in mediating post liver transplantation ALI and that pretreatment with the anesthetic propofol, known to inhibit gap junction, can confer effective protection.

METHODS

Male Sprague-Dawley rats underwent autologous orthotopic liver transplantation (AOLT) in the absence or presence of treatments with the selective Cx43 inhibitor, enanthol (0.1 mg/kg) and propofol (50 mg/kg), a commonly used anesthetic in clinical anesthesia. In vitro study, BEAS-2B cells, a kind of lung epithelial cell line expressing Cx43, exposed to lipopolysaccharide (LPS), which mainly contributed to ALI. Function of Cx43 GJ was regulated by Cx43 specific inhibitors, gap26 (300 μM) or enhancer, retinoic acid (10 μM) and two specific siRNAs.

RESULTS

Compared with the sham group, AOLT results in ALI obviously with plasma endotoxin increase. Cx43 inhibition decreased ALI through inflammatory reaction reduction. In vitro studies, LPS-induced BEAS-2B cells damage was attenuated by Cx43 function inhibition, but amplified by enhancement. Another important finding was propofol reduced Cx43 function and protected against LPS-mediated BEAS-2B cells damage or AOLT-induced ALI, mechanisms of which were also associated with inflammatory reaction decrease.

CONCLUSION

Cx43 plays a vital role in liver transplantation-induced ALI. Propofol decreased Cx43 function and protected against ALI in vivo and in vitro. This finding provide a new basis for targeted intervention of organ protection in liver transplantation, even in other kinds of operations.

Severe hypoxemia: which strategy to choose

BACKGROUND

Acute respiratory distress syndrome (ARDS) is characterized by a noncardiogenic pulmonary edema with bilateral chest X-ray opacities and reduction in lung compliance, and the hallmark of the syndrome is hypoxemia refractory to oxygen therapy. Severe hypoxemia (PaO2/FiO2 < 100 mmHg), which defines severe ARDS, can be found in 20-30 % of the patients and is associated with the highest mortality rate. Although the standard supportive treatment remains mechanical ventilation (noninvasive and invasive), possible adjuvant therapies can be considered. We performed an up-to-date clinical review of the possible available strategies for ARDS patients with severe hypoxemia.

MAIN RESULTS

In summary, in moderate-to-severe ARDS or in the presence of other organ failure, noninvasive ventilatory support presents a high risk of failure: in those cases the risk/benefit of delayed mechanical ventilation should be evaluated carefully. Tailoring mechanical ventilation to the individual patient is fundamental to reduce the risk of ventilation-induced lung injury (VILI): it is mandatory to apply a low tidal volume, while the optimal level of positive end-expiratory pressure should be selected after a stratification of the severity of the disease, also taking into account lung recruitability; monitoring transpulmonary pressure or airway driving pressure can help to avoid lung overstress. Targeting oxygenation of 88-92 % and tolerating a moderate level of hypercapnia are a safe choice. Neuromuscular blocking agents (NMBAs) are useful to maintain patient-ventilation synchrony in the first hours; prone positioning improves oxygenation in most cases and promotes a more homogeneous distribution of ventilation, reducing the risk of VILI; both treatments, also in combination, are associated with an improvement in outcome if applied in the acute phase in the most severe cases. The use of extracorporeal membrane oxygenation (ECMO) in severe ARDS is increasing worldwide, but because of a lack of randomized trials is still considered a rescue therapy.

CONCLUSION

Severe ARDS patients should receive a holistic framework of respiratory and hemodynamic support aimed to ensure adequate gas exchange while minimizing the risk of VILI, by promoting lung recruitment and setting protective mechanical ventilation. In the most severe cases, NMBAs, prone positioning, and ECMO should be considered.

[Critical care management of intracerebral hemorrhage]

BACKGROUND

Intracerebral hemorrhage accounts for up to 20 % percent of all ischemic strokes. In addition to a higher mortality, they are often associated with severe neurological impairment for those affected.

OBJECTIVES

Review of the current literature and guidelines addressing the critical care management of spontaneous intracerebral hemorrhage, including treatments to reduce primary and secondary neurological damage.

RESULTS

Acute blood pressure lowering to less than 140 mmHg should be aspired immediately after intensive care admission. During the following days blood pressure variability should be minimized. Preexisting oral anticoagulation should be immediately reversed, while hemostatic therapy not associated with reversal of antithrombotic therapy should not be applied. Surgery for patients with impaired consciousness should be discussed. Use of pneumatic compression in immobile patients is recommended. Developing intracranial hypertension should be treated with combined physical and pharmacological measures in a stepwise approach. Administration of glucocorticoids is currently not recommended.

CONCLUSIONS

Critical care management of spontaneous hemorrhage demands a multimodal, graded approach for reduction of both primary and secondary neurological damage.

The standard of care of patients with ARDS: ventilatory settings and rescue therapies for refractory hypoxemia

Purpose

Severe ARDS is often associated with refractory hypoxemia, and early identification and treatment of hypoxemia is mandatory. For the management of severe ARDS ventilator settings, positioning therapy, infection control, and supportive measures are essential to improve survival.

Methods and results

A precise definition of life-threating hypoxemia is not identified. Typical clinical determinations are: arterial partial pressure of oxygen < 60 mmHg and/or arterial oxygenation < 88 % and/or the ratio of PaO₂/FIO₂ < 100. For mechanical ventilation specific settings are recommended: limitation of tidal volume (6 ml/kg predicted body weight), adequate high PEEP (>12 cmH₂O), a recruitment manoeuvre in special situations, and a ‘balanced’ respiratory rate (20-30/min). Individual bedside methods to guide PEEP/recruitment (e.g., transpulmonary pressure) are not (yet) available. Prone positioning [early (≤ 48 hrs after onset of severe ARDS) and prolonged (repetition of 16-hr-sessions)] improves survival. An advanced infection management/control includes early diagnosis of bacterial, atypical, viral and fungal specimen (blood culture, bronchoalveolar lavage), and of infection sources by CT scan, followed by administration of broad-spectrum anti-infectives. Neuromuscular blockage (Cisatracurium ≤ 48 hrs after onset of ARDS), as well as an adequate sedation strategy (score guided) is an important supportive therapy. A negative fluid balance is associated with improved lung function and the use of hemofiltration might be indicated for specific indications.

Conclusions

A specific standard of care is required for the management of severe ARDS with refractory hypoxemia.

Influence of quality of care and individual patient characteristics on quality of life and return to work in survivors of the acute respiratory distress syndrome: protocol for a prospective, observational, multi-centre patient cohort study (DACAPO)

BACKGROUND

Health-related quality of life (HRQoL) and return to work are important outcomes in critical care medicine, reaching beyond mortality. Little is known on factors predictive of HRQoL and return to work in critical illness, including the acute respiratory distress syndrome (ARDS), and no evidence exists on the role of quality of care (QoC) for outcomes in survivors of ARDS. It is the aim of the DACAPO study ("Surviving ARDS: the influence of QoC and individual patient characteristics on quality of life") to investigate the role of QoC and individual patient characteristics on quality of life and return to work.

METHODS/DESIGN

A prospective, observational, multi-centre patient cohort study will be performed in Germany, using hospitals from the "ARDS Network Germany" as the main recruiting centres. It is envisaged to recruit 2400 patients into the DACAPO study and to analyse a study population of 1500 survivors. They will be followed up until 12 months after discharge from hospital. QoC will be assessed as process quality, structural quality and volume at the institutional level. The main outcomes (HRQoL and return to work) will be assessed by self-report questionnaires. Further data collection includes general medical and ARDS-related characteristics of patients as well as sociodemographic and psycho-social parameters. Multilevel hierarchical modelling will be performed to analyse the effects of QoC and individual patient characteristics on outcomes, taking the cluster structure of the data into account.

DISCUSSION

By obtaining comprehensive data at patient and hospital level using a prospective multi-centre design, the DACAPO-study is the first study investigating the influence of QoC on individual outcomes of ARDS survivors.

Endovascular repair for acute traumatic transection of the descending thoracic aorta: experience of a single centre with a 12-years follow up

Background

Most blunt aortic injuries occur in the proximal proximal descending aorta causing acute transection of this vessel. Generally, surgical repair of the ruptured segment of aorta is associated with high rates of morbidity and mortality and in this view endovascular treatment seems to be a valid and safer alternative. Aim of this article is to review our experience with endovascular approach for the treatment of acute traumatic rupture of descending thoracic aorta.

Methods

From April 2002 to November 2014, 11 patients (9 males and 2 females) were referred to our Department with a diagnosis of acute transection of thoracic aorta. Following preoperative Computed Tomography (CT) evaluation, thoracic endovascular aortic repair (TEVAR) with left subclavian artery coverage was performed. Follow-up consisted clinical and instrumental (CT, Duplex ultrasound) controls at discharge, 1, 3 and 6 months and yearly thereafter.

Results

At 12-year follow up, the overall survival for the entire patients cohort was 100 %, no major or minor neurological complications and no episode of left arm claudication occurred. Cardiovascular, respiratory and bleeding complications, in the early period, was represented by minor, non fatal events. No stent graft failure, collapse, leak or distal migration were detected at CT scan during the entire follow up period.

Conclusions

According to our experience, despite the small number of patient population, TEVAR procedure with with left subclavian artery coverage, performed in emergency settings, seems to provide excellent long term results.

Trials registration

The protocol was registered at a public trials registry, www.clinicaltrials.gov (trial identifier NCT02376998).

Pressure-controlled versus volume-controlled ventilation for acute respiratory failure due to acute lung injury (ALI) or acute respiratory distress syndrome (ARDS)

BACKGROUND

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) account for one-quarter of cases of acute respiratory failure in intensive care units (ICUs). A third to half of patients will die in the ICU, in hospital or during follow-up. Mechanical ventilation of people with ALI/ARDS allows time for the lungs to heal, but ventilation is invasive and can result in lung injury. It is uncertain whether ventilator-related injury would be reduced if pressure delivered by the ventilator with each breath is controlled, or whether the volume of air delivered by each breath is limited.

OBJECTIVES

To compare pressure-controlled ventilation (PCV) versus volume-controlled ventilation (VCV) in adults with ALI/ARDS to determine whether PCV reduces in-hospital mortality and morbidity in intubated and ventilated adults.

SEARCH METHODS

In October 2014, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2014, Isssue 9), MEDLINE (1950 to 1 October 2014), EMBASE (1980 to 1 October 2014), the Latin American Caribbean Health Sciences Literature (LILACS) (1994 to 1 October 2014) and Science Citation Index-Expanded (SCI-EXPANDED) at the Institute for Scientific Information (ISI) Web of Science (1990 to 1 October 2014), as well as regional databases, clinical trials registries, conference proceedings and reference lists.

SELECTION CRITERIA

Randomized controlled trials (RCTs) and quasi-RCTs (irrespective of language or publication status) of adults with a diagnosis of acute respiratory failure or acute on chronic respiratory failure and fulfilling the criteria for ALI/ARDS as defined by the American-European Consensus Conference who were admitted to an ICU for invasive mechanical ventilation, comparing pressure-controlled or pressure-controlled inverse-ratio ventilation, or an equivalent pressure-controlled mode (PCV), versus volume-controlled ventilation, or an equivalent volume-controlled mode (VCV).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened and selected trials, assessed risk of bias and extracted data. We sought clarification from trial authors when needed. We pooled risk ratios (RRs) for dichotomous data and mean differences (MDs) for continuous data with their 95% confidence intervals (CIs) using a random-effects model. We assessed overall evidence quality using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) approach.

MAIN RESULTS

We included three RCTs that randomly assigned a total of 1089 participants recruited from 43 ICUs in Australia, Canada, Saudi Arabia, Spain and the USA. Risk of bias of the included studies was low. Only data for mortality and barotrauma could be combined in the meta-analysis. We downgraded the quality of evidence for the three mortality outcomes on the basis of serious imprecision around the effect estimates. For mortality in hospital, the RR with PCV compared with VCV was 0.83 (95% CI 0.67 to 1.02; three trials, 1089 participants; moderate-quality evidence), and for mortality in the ICU, the RR with PCV compared with VCV was 0.84 (95% CI 0.71 to 0.99; two trials, 1062 participants; moderate-quality evidence). One study provided no evidence of clear benefit with the ventilatory mode for mortality at 28 days (RR 0.88, 95% CI 0.73 to 1.06; 983 participants; moderate-quality evidence). The difference in effect on barotrauma between PCV and VCV was uncertain as the result of imprecision and different co-interventions used in the studies (RR 1.24, 95% CI 0.87 to 1.77; two trials, 1062 participants; low-quality evidence). Data from one trial with 983 participants for the mean duration of ventilation, and from another trial with 78 participants for the mean number of extrapulmonary organ failures that developed with PCV or VCV, were skewed. None of the trials reported on infection during ventilation or quality of life after discharge.

AUTHORS' CONCLUSIONS

Currently available data from RCTs are insufficient to confirm or refute whether pressure-controlled or volume-controlled ventilation offers any advantage for people with acute respiratory failure due to acute lung injury or acute respiratory distress syndrome. More studies including a larger number of people given PCV and VCV may provide reliable evidence on which more firm conclusions can be based.