Lung-protective Ventilation In Patients Research Articles

Rationale and study design for an Individualized PeriopeRative Open lung VEntilatory approach in Emergency Abdominal Laparotomy/scopy: study protocol for a prospective international randomized controlled trial

BackgroundPostoperative pulmonary complications (PPC) are the most frequent postoperative complications, with an estimated prevalence in elective surgery ranging from 20% in observational cohort studies to 40% in randomized clinical trials. However, the prevalence of PPCs in patients undergoing emergency abdominal surgery is not well defined. Lung-protective ventilation aims to minimize ventilator-induced lung injury and reduce PPCs. The open lung approach (OLA), which combines recruitment manoeuvres (RM) and positive end-expiratory pressure (PEEP) titration, aims to minimize areas of atelectasis and the development of PPCs; however, there is no conclusive evidence in the literature that OLA can prevent PPCs. The purpose of this study is to compare an individualized perioperative OLA with conventional standardized lung-protective ventilation in patients undergoing emergency abdominal surgery with clinical signs of intraoperative lung collapse. MethodsRandomized international clinical trial to compare an individualized perioperative OLA (RM plus individualized PEEP and individualized postoperative respiratory support) with conventional lung-protective ventilation (standard PEEP of 5 cmH2O and conventional postoperative oxygen therapy) in patients undergoing emergency abdominal surgery with clinical signs of lung collapse. Patients will be randomised to open-label parallel groups. The primary outcome is any severe PPC during the first 7 postoperative days, including: acute respiratory failure, pneumothorax, weaning failure, acute respiratory distress syndrome, and pulmonary infection. The estimated sample size is 732 patients (366 per group). The final sample size will be readjusted during the interim analysis. DiscussionThe Individualized Perioperative Open-lung Ventilatory Strategy in emergency abdominal laparotomy (iPROVE-EAL) is the first multicentre, randomized, controlled trial to investigate whether an individualized perioperative approach prevents PPCs in patients undergoing emergency surgery.

Findings of ventilator-measured P0.1 in assessing respiratory drive in patients with severe ARDS.

Providers should adjust the depth of sedation to promote lung-protective ventilation in patients with severe ARDS. This recommendation was based on the assumption that the depth of sedation could be used to assess respiratory drive. To assess the association between respiratory drive and sedation in patients with severe ARDS by using ventilator-measured P0.1 and RASS score. Loss of spontaneous breathing was observed within 48 h of mechanical ventilation in patients with severe ARDS, and spontaneous breathing returned after 48 hours. P0.1 was measured by ventilator every 12 ± 2 hours, and the RASS score was measured synchronously. The RASS score was moderately correlated with P0.1 (R𝑆𝑝𝑒𝑎𝑟𝑚𝑎𝑛, 0.570; 95% CI, 0.475 to 0.637; p= 0.00). However, only patients with a RASS score of -5 were considered to have no excessive respiratory drive, but there was a risk for loss of spontaneous breathing. A P0.1 exceeding 3.5 cm H2O in patients with other RASS scores indicated an increase in respiratory drive. RASS score has little clinical significance in evaluating respiratory drive in severe ARDS. P0.1 should be evaluated by ventilator when adjusting the depth of sedation to promote lung-protective ventilation.

Individualised, perioperative open-lung ventilation strategy during one-lung ventilation (iPROVE-OLV): a multicentre, randomised, controlled clinical trial

It is uncertain whether individualisation of the perioperative open-lung approach (OLA) to ventilation reduces postoperative pulmonary complications in patients undergoing lung resection. We compared a perioperative individualised OLA (iOLA) ventilation strategy with standard lung-protective ventilation in patients undergoing thoracic surgery with one-lung ventilation. This multicentre, randomised controlled trial enrolled patients scheduled for open or video-assisted thoracic surgery using one-lung ventilation in 25 participating hospitals in Spain, Italy, Turkey, Egypt, and Ecuador. Eligible adult patients (age ≥18 years) were randomly assigned to receive iOLA or standard lung-protective ventilation. Eligible patients (stratified by centre) were randomly assigned online by local principal investigators, with an allocation ratio of 1:1. Treatment with iOLA included an alveolar recruitment manoeuvre to 40 cm H2O of end-inspiratory pressure followed by individualised positive end-expiratory pressure (PEEP) titrated to best respiratory system compliance, and individualised postoperative respiratory support with high-flow oxygen therapy. Participants allocated to standard lung-protective ventilation received combined intraoperative 4 cm H2O of PEEP and postoperative conventional oxygen therapy. The primary outcome was a composite of severe postoperative pulmonary complications within the first 7 postoperative days, including atelectasis requiring bronchoscopy, severe respiratory failure, contralateral pneumothorax, early extubation failure (rescue with continuous positive airway pressure, non-invasive ventilation, invasive mechanical ventilation, or reintubation), acute respiratory distress syndrome, pulmonary infection, bronchopleural fistula, and pleural empyema. Due to trial setting, data obtained in the operating and postoperative rooms for routine monitoring were not blinded. At 24 h, data were acquired by an investigator blinded to group allocation. All analyses were performed on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov, NCT03182062, and is complete. Between Sept 11, 2018, and June 14, 2022, we enrolled 1380 patients, of whom 1308 eligible patients (670 [434 male, 233 female, and three with missing data] assigned to iOLA and 638 [395 male, 237 female, and six with missing data] to standard lung-protective ventilation) were included in the final analysis. The proportion of patients with the composite outcome of severe postoperative pulmonary complications within the first 7 postoperative days was lower in the iOLA group compared with the standard lung-protective ventilation group (40 [6%] vs 97 [15%], relative risk 0·39 [95% CI 0·28 to 0·56]), with an absolute risk difference of -9·23 (95% CI -12·55 to -5·92). Recruitment manoeuvre-related adverse events were reported in five patients. Among patients subjected to lung resection under one-lung ventilation, iOLA was associated with a reduced risk of severe postoperative pulmonary complications when compared with conventional lung-protective ventilation. Instituto de Salud Carlos III and the European Regional Development Funds.

Physiological effects of lung-protective ventilation in patients with lung fibrosis and usual interstitial pneumonia pattern versus primary ARDS: a matched-control study

BackgroundAlthough patients with interstitial pneumonia pattern (ILD-UIP) and acute exacerbation (AE) leading to severe acute respiratory failure may require invasive mechanical ventilation (MV), physiological data on lung mechanics during MV are lacking. We aimed at describing the physiological effect of lung-protective ventilation in patients with AE-ILD-UIP compared with primary ARDS.MethodsPartitioned lung and chest wall mechanics were assessed in a series of AE-ILD-UIP patients matched 1:1 with primary ARDS as controls (based on BMI and PaO2/FiO2 ratio). Three PEEP levels (zero = ZEEP, 4–8 cmH2O = PEEPLOW, and titrated to achieve positive end-expiratory transpulmonary pressure PL,EE = PEEPTITRATED) were used for measurements.ResultsTen AE-ILD-UIP patients and 10 matched ARDS were included. In AE-ILD-UIP median PL,EE at ZEEP was − 4.3 [− 7.6– − 2.3] cmH2O and lung elastance (EL) 44 [40–51] cmH2O/L. At PEEPLOW, PL,EE remained negative and EL did not change (p = 0.995) versus ZEEP. At PEEPTITRATED, PL,EE increased to 0.8 [0.3–1.5] cmH2O and EL to 49 [43–59] (p = 0.004 and p < 0.001 compared to ZEEP and PEEPLOW, respectively). ΔPL decreased at PEEPLOW (p = 0.018) and increased at PEEPTITRATED (p = 0.003). In matched ARDS control PEEP titration to obtain a positive PL,EE did not result in significant changes in EL and ΔPL.ConclusionsIn mechanically ventilated AE-ILD-UIP patients, differently than in patients with primary ARDS, PEEP titrated to obtain a positive PL,EE significantly worsened lung mechanics.

Effect of individualized intraoperative lung recruitment maneuver on postoperative pulmonary complications in patients undergoing upper abdominal surgeries under general anesthesia

ABSTRACT Background The concept of lung protective ventilation (LPV) during general anesthesia (GA) aims at minimizing lung injury and postoperative pulmonary complications (POPCs). Recruitment maneuver (RM) as a part of LPV may improve lung mechanics and oxygenation, but despite extensive research, definitive guidelines for the applications of intraoperative RMs have not been established yet. Methods This study was a prospective, single-blinded, randomized clinical trial. Sixty-six subjects undergoing non-laparoscopic upper abdominal surgeries under GA were randomly assigned into two equal groups. Control group (C) received tidal volume of 8 ml/kg predicted body weight (PBW) and positive end expiratory pressure (PEEP) of 5 cmH2O without RM. Recruitment group (R) received tidal volume of 8 ml/kg PBW with stepwise RMs and individualized PEEP titration after each RM. Compliance, plateau pressure, driving pressure, SpO2 and hemodynamics were monitored at each step of RM. POPCs, length of hospital stay and mortality were recorded postoperatively. Results There was a significant reduction in POPCs in (R) group than in (C) group (P = 0.03). Also, there was a significant increase in compliance before extubation in (R) group (P = 0.001). However, no significant difference was noted between both groups as regards mortality rate and length of hospital stay. Conclusion Individualized stepwise lung RM significantly decreases the incidence of POPCs when added to LPV in patients undergoing non-laparoscopic upper abdominal surgeries under GA.

Extracorporeal Carbon Dioxide Removal: From Pathophysiology to Clinical Applications; Focus on Combined Continuous Renal Replacement Therapy.

Lung-protective ventilation (LPV) with low tidal volumes can significantly increase the survival of patients with acute respiratory distress syndrome (ARDS) by limiting ventilator-induced lung injuries. However, one of the main concerns regarding the use of LPV is the risk of developing hypercapnia and respiratory acidosis, which may limit the clinical application of this strategy. This is the reason why different extracorporeal CO2 removal (ECCO2R) techniques and devices have been developed. They include low-flow or high-flow systems that may be performed with dedicated platforms or, alternatively, combined with continuous renal replacement therapy (CRRT). ECCO2R has demonstrated effectiveness in controlling PaCO2 levels, thus allowing LPV in patients with ARDS from different causes, including those affected by Coronavirus disease 2019 (COVID-19). Similarly, the suitability and safety of combined ECCO2R and CRRT (ECCO2R-CRRT), which provides CO2 removal and kidney support simultaneously, have been reported in both retrospective and prospective studies. However, due to the complexity of ARDS patients and the limitations of current evidence, the actual impact of ECCO2R on patient outcome still remains to be defined. In this review, we discuss the main principles of ECCO2R and its clinical application in ARDS patients, in particular looking at clinical experiences of combined ECCO2R-CRRT treatments.

Duration of Noninvasive Respiratory Support and Extracorporeal Membrane Oxygenation Outcomes: Connecting the Dots.

To the Editor: We thank Lo Presti et al.1 for their letter related to our examination of the impact of duration of noninvasive respiratory support (RS) in patients with COVID-19 supported with extracorporeal membrane oxygenation (ECMO). The points raised highlight the challenges faced in the retrospective analysis of a complex disease process. The inability to account for baseline triage characteristics, lung compliance, or reason for RS failure are valid critiques of our analysis. Without reservation, our study should be viewed in the context of rapidly emerging evidence related to the support of patients with COVID-19. Given the absence of prospective trials, clinicians are left to weigh available indirect evidence that the duration of RS may be associated with worse outcomes in this context. Since authoring our manuscript, several additional studies have further corroborated our group’s findings. We wish to draw attention to these works, discuss the relevance to our findings, and emphasize the need for further investigation in this domain. First, Barbaro et al.2 presented registry data of patients with COVID-19 supported with ECMO. These investigators identified an increase in mortality over the course of the pandemic. What changed during this period to account for this observation? The authors postulated several reasons, of which, changes in pre-ECMO treatment and more frequent employment of noninvasive ventilation relate specifically to our findings. Similarly, Braaten et al.3 analyzed temporal trends in ECMO outcomes and found worse mortality in patients supported with ECMO later in the pandemic, and further, that longer time from admission to ECMO cannulation was associated with worse ECMO outcomes. In our cohort, a longer duration of RS (days) was significantly associated with a diminished rate of ECMO decannulation (sHR: 0.93; 95% CI, 0.87–0.98), whereas the duration of invasive mechanical ventilation (IMV) (sHR: 0.98; 95% CI, 0.88–1.09) was not. Moreover, the duration of RS remained significantly associated with worse ECMO outcomes even when adjusted for the duration of IMV.4 Though we dichotomize the duration of RS by median duration in our article, the precise threshold duration of RS associated with the poorest outcomes remains to be elucidated. The finding that duration of IMV is not related to ECMO outcomes in COVID-19 has been replicated by other investigators.5,6 Notably, Riera et al.6 reported days from symptoms to cannulation (possibly reflective of prolonged RS), but not IMV days, were independently associated with mortality. ECMO is a tool to decrease the physiologic insult of IMV by facilitating less damaging native lung ventilation strategies. It reasons that violation of lung-protective goals either during IMV or before tracheal intubation would similarly result in lung damage and worse overall outcomes. Clinician awareness and implementation of lung-protective ventilation in patients receiving IMV have likely improved over time and may explain the absence of impact of IMV duration on ECMO outcomes seen in patients with COVID-19. Paradoxically, crisis care during the current pandemic may have resulted in more frequent violation of lung-protective metrics via deleterious RS settings as a strategy to avoid IMV. Direct evidence implicating the duration of RS to worse ECMO outcomes in patients with COVID-19 is limited but growing. Connecting the dots of available evidence supports our preliminary findings, and we, like Lo Presti et al.5, support a prospective study of this hypothesis.

Monitoring Expired CO2 Kinetics to Individualize Lung-Protective Ventilation in Patients With the Acute Respiratory Distress Syndrome.

Mechanical ventilation (MV) is a lifesaving supportive intervention in the management of acute respiratory distress syndrome (ARDS), buying time while the primary precipitating cause is being corrected. However, MV can contribute to a worsening of the primary lung injury, known as ventilation-induced lung injury (VILI), which could have an important impact on outcome. The ARDS lung is characterized by diffuse and heterogeneous lung damage and is particularly prone to suffer the consequences of an excessive mechanical stress imposed by higher airway pressures and volumes during MV. Of major concern is cyclic overdistension, affecting those lung segments receiving a proportionally higher tidal volume in an overall reduced lung volume. Theoretically, healthier lung regions are submitted to a larger stress and cyclic deformation and thus at high risk for developing VILI. Clinicians have difficulties in detecting VILI, particularly cyclic overdistension at the bedside, since routine monitoring of gas exchange and lung mechanics are relatively insensitive to this mechanism of VILI. Expired CO2 kinetics integrates relevant pathophysiological information of high interest for monitoring. CO2 is produced by cell metabolism in large daily quantities. After diffusing to tissue capillaries, CO2 is transported first by the venous and then by pulmonary circulation to the lung. Thereafter diffusing from capillaries to lung alveoli, it is finally convectively transported by lung ventilation for its elimination to the atmosphere. Modern readily clinically available sensor technology integrates information related to pulmonary ventilation, perfusion, and gas exchange from the single analysis of expired CO2 kinetics measured at the airway opening. Current volumetric capnography (VCap), the representation of the volume of expired CO2 in one single breath, informs about pulmonary perfusion, end-expiratory lung volume, dead space, and pulmonary ventilation inhomogeneities, all intimately related to cyclic overdistension during MV. Additionally, the recently described capnodynamic method provides the possibility to continuously measure the end-expiratory lung volume and effective pulmonary blood flow. All this information is accessed non-invasively and breath-by-breath helping clinicians to personalize ventilatory settings at the bedside and minimize overdistension and cyclic deformation of lung tissue.

Mechanical ventilation in septic shock

The aim of this study was to review the most recent literature on mechanical ventilation strategies in patients with septic shock. Indirect clinical trial evidence has refined the use of neuromuscular blocking agents, positive end-expiratory pressure (PEEP) and recruitment manoeuvres in septic shock patients with acute respiratory distress syndrome. Weaning strategies and devices have also been recently evaluated. The role of lung protective ventilation in patients with healthy lungs, while recognized, still needs to be further refined. The possible detrimental effects of spontaneous breathing in patients who develop acute respiratory distress syndrome is increasingly recognized, but clinical trial evidence is still lacking to confirm this hypothesis. A new concept of lung and diaphragm protective is emerging in the critical care literature, but its application will need a complex intervention implementation approach to allow adequate scrutiny of this concept and uptake by clinicians. Many advances in the management of the mechanically ventilated patient with sepsis and septic shock have occurred in recent years, but clinical trial evidence is still necessary to translate new hypotheses to the bedside and find the right balance between benefits and risks of these new strategies.

Abstract 261: Acute Lung Injury and Recovery in Patients with Refractory Vf/vt Cardiac Arrest Treated with Prolonged Cpr and Veno Arterial Extracorporeal Membrane Oxygenation

Background: Post cardiac arrest syndrome includes significant pulmonary injury that is not clearly understood. Objectives: Describe the lung injury patterns among patients presenting with refractory ventricular tachycardia/ventricular fibrillation out-of-hospital cardiac arrest (VT/VF OHCA) patients who were treated with veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Methods: OHCA characteristics, post-arrest computed tomography (CT) scans, ventilator parameters and complications were collected using a retrospective cohort design. Changes in lung compliance were compared over time between survivors, patients with acute brain death and those who had other modes of death with a two- way analysis of variance. Results: Among138 refractory VT/VF OHCA patients (81% were male with a median age of 59.0 years, mean CPR time of 64.3 ±16.1 min, a mean APACHE II score of 30.5 ± 4.6) 48/138 (34.8%) survived, acute brain death occurred in 48/138 (34.8%) and other modes of death in 56/138 (40.6%). The dependent posterior segments of the lung were the most commonly affected areas on the initial CT scan(Fig1A). There was no difference in the number of hyperattenuated areas between the survival groups.Compliance was borderline on day one (median 26.3(19.3,33.3)ml/cmH 2 0), but improved throughout the hospitalization (p=0.001) and was higher in survivors compared to those who died (p&lt;0.001, Fig1B). VA-ECMO allowed the use of lung-protective ventilation in patients with borderline compliances maintaining safe PaO2 and PaCO2. Patients additionally treated with IABP/Impella had lower pulmonary compliance and more hyperattenuated areas on their initial CT scan compared to those treated exclusively with VA-ECMO. Conclusions: Refractory VT/VF OHCA patients who are treated with VA-ECMO frequently have lung injury with borderline compliance soon after the index event. Lung compliance improves throughout hospitalization and is higher in survivors.

Higher Class of Obesity Is Associated With Delivery of Higher Tidal Volumes in Subjects With ARDS.

Obese subjects are at higher risk of development and progression of ARDS. There are limited data regarding mechanical ventilation practices and use of adjunctive therapies in subjects with ARDS across different obesity classes. We hypothesized that the adherence to lung-protective ventilation would be worse with rising body mass index class in patients with ARDS. We conducted a retrospective observational study of subjects with ARDS. We evaluated the differences in ventilator settings, airway pressures, gas exchange, use of rescue therapies, length of hospital stay, and mortality among subjects based on the obesity classes of the WHO. The study included 613 subjects with ARDS: 21.4% were normal weight, 25% were overweight, and 53.7% were obese; 33.3% of the obese subjects met criteria for class I-II obesity, while 20.4% were class III obese (morbid obesity). On day 1, 53% of subjects with class III obesity had tidal volumes > 8 mL/kg, compared to 26% of the subjects with normal weight. In addition, 48% of the morbidly obese subjects received at least one rescue therapy as compared to 37% of normal weight subjects and 36% of overweight subjects. There were significant differences in the use of rescue therapies among the groups. In a multivariable model, subjects with class III obesity were significantly more likely to receive tidal volume > 8 mL/kg predicted body weight on day 1 when compared with subjects with normal weight (odds ratio 3.14, 95% CI 1.78-5.57). There was no difference in length of stay in ICU or hospital, duration of mechanical ventilation, or adjusted ICU or hospital mortality among the 4 groups. In this study, the risk of exposure to higher tidal volumes and the need for specific rescue therapies rose with higher classes of obesity in subjects with ARDS. More research is needed to identify how to better implement lung-protective ventilation in patients with obesity.

The tidal volume fix and more….

In the past 30 years the medical literature has been enriched with numerous publications reporting on randomized clinical trials, meta-analysis and service reviews on invasive ventilation in critically ill patients ( Figure 1 ). For many years the investigations on lung-protective ventilation focused on patients with acute respiratory distress syndrome (ARDS). Interest in the effects of lung-protective ventilation in patients without ARDS is rapidly increasing, however, resulting in a steep rise of the number of publications on lung-protection in patients without ARDS.

Assessment of Therapeutic Interventions and Lung Protective Ventilation in Patients With Moderate to Severe Acute Respiratory Distress Syndrome

A number of interventions are available to manage patients with moderate to severe acute respiratory distress syndrome (ARDS). However, the associations of currently available ventilatory strategies and adjunctive therapies with mortality are uncertain. To compare and rank different therapeutic strategies to identify the best intervention associated with a reduction in mortality in adult patients with moderate to severe ARDS. An electronic search of MEDLINE, MEDLINE In-Process/ePubs Ahead of Print, Embase, Cochrane Controlled Clinical Trial Register (Central), PubMed, and CINAHL was conducted, from database inception to May 29, 2019. Randomized clinical trials of interventions for adults with moderate to severe ARDS that used lung protective ventilation. No language restrictions were applied. Data were independently extracted by 2 reviewers and synthesized with Bayesian random-effects network meta-analyses. The primary outcome was 28-day mortality. Barotrauma was a secondary outcome. Among 25 randomized clinical trials evaluating 9 interventions, 2686 of 7743 patients (34.6%) died within 28 days. Compared with lung protective ventilation alone, prone positioning and venovenous extracorporeal membrane oxygenation were associated with significantly lower 28-day mortality (prone positioning: risk ratio, 0.69; 95% credible interval, 0.48-0.99; low quality of evidence; venovenous extracorporeal membrane oxygenation: risk ratio, 0.60; 95% credible interval, 0.38-0.93; moderate quality of evidence). These 2 interventions had the highest ranking probabilities, although they were not significantly different from each other. Among 18 trials reporting on barotrauma, 448 of 6258 patients (7.2%) experienced this secondary outcome. No intervention was superior to any other in reducing barotrauma, and each represented low to very low quality of evidence. This network meta-analysis supports the use of prone positioning and venovenous extracorporeal membrane oxygenation in addition to lung protective ventilation in patients with ARDS. Moreover, venovenous extracorporeal membrane oxygenation may be considered as an early strategy for adults with severe ARDS receiving lung protective ventilation.

Effects of Stepwise Lung Recruitment Maneuvers in Patients with Early Acute Respiratory Distress Syndrome: A Prospective, Randomized, Controlled Trial.

Since the clinical benefit of lung recruitment maneuvers (LRMs) is still conflicting, we performed this prospective, randomized, controlled study to investigate whether LRMs should be used in the routine management of acute respiratory distress syndrome (ARDS). This trial was conducted in four intensive care units (ICUs) to compare application of a modified stepwise LRMs with solely lung-protective ventilation in patients with moderate to severe ARDS within 72 h from the onset. The primary outcome was 28-day mortality, and the secondary outcomes were ventilator-free days and ICU-free days. We collected data on 120 ARDS patients from 2009 to 2012, and there was no difference in 28-day mortality between the two groups (28.3% vs. 30.0%, p = 0.84). However, among survivors, patients in the LRM group had a significant longer median duration of ventilator-free days (18 vs. 13 days; p = 0.04) and ICU-free days (16 vs. 11 days; p = 0.03) at 28 days than in the control group. The respiratory system compliance was significantly higher in the LRM group from day 1 to day 7. The occurrence rate of barotrauma was similar in both groups. We concluded that LRMs combined with lung-protective ventilation in early ARDS may improve patient outcomes.

Bedside respiratory physiology to detect risk of lung injury in acute respiratory distress syndrome.

The most effective strategies for treating the patient with acute respiratory distress syndrome center on minimizing ventilation-induced lung injury (VILI). Yet, current standard-of-care does little to modify mechanical ventilation to patient-specific risk. This review focuses on evaluation of bedside respiratory mechanics, which when interpreted in patient-specific context, affords opportunity to individualize lung-protective ventilation in patients with acute respiratory distress syndrome. Four biophysical mechanisms of VILI are widely accepted: volutrauma, barotrauma, atelectrauma, and stress concentration. Resulting biotrauma, that is, local and systemic inflammation and endothelial activation, may be thought of as the final common pathway that propagates VILI-mediated multiorgan failure. Conventional, widely utilized techniques to assess VILI risk rely on airway pressure, flow, and volume changes, and remain essential tools for determining overdistension of aerated lung regions, particularly when interpreted cognizant of their limitations. Emerging bedside tools identify regional differences in mechanics, but further study is required to identify how they might best be incorporated into clinical practice. Quantifying patient-specific risk of VILI requires understanding each patient's pulmonary mechanics in context of biological predisposition. Tailoring support at bedside according to these factors affords the greatest opportunity to date for mitigating VILI and alleviating associated morbidity.

Minimal-flow ECCO2R in patients needing CRRT does not facilitate lung-protective ventilation.

Extracorporeal CO2 removal (ECCO2R) is intended to facilitate lung protective ventilation in patients with hypercarbia. The combination of continuous renal replacement therapy (CRRT) and minimal-flow ECCO2R offers a promising concept for patients in need of both. We hypothecated that this system is able to remove enough CO2 to facilitate lung protective ventilation in mechanically ventilated patients. In 11 ventilated patients with acute renal failure who received either pre- or postdilution CRRT, minimal-flow ECCO2R was added to the circuit. During 6 h of combined therapy, CO2 removal and its effect on facilitation of lung-protective mechanical ventilation were assessed. Ventilatory settings were kept in assisted or pressure-controlled mode allowing spontaneous breathing. With minimal-flow ECCO2R significant decreases in minute ventilation, tidal volume and paCO2 were found after one and three but not after 6 h of therapy. Nevertheless, no significant reduction in applied force was found at any time during combined therapy. CO2 removal was 20.73ml CO2/min and comparable between pre- and postdilution CRRT. Minimal-flow ECCO2R in combination with CRRT is sufficient to reduce surrogates for lung-protective mechanical ventilation but was not sufficient to significantly reduce force applied to the lung. Causative might be the absolute amount of CO2 removal of only about 10% of resting CO2 production in an adult as we found. The benefit of applying minimal flow ECCO2R in an uncontrolled setting of mechanical ventilation might be limited.

Patients with uninjured lungs may also benefit from lung-protective ventilator settings.

Although mechanical ventilation is a life-saving strategy in critically ill patients and an indispensable tool in patients under general anesthesia for surgery, it also acts as a double-edged sword. Indeed, ventilation is increasingly recognized as a potentially dangerous intrusion that has the potential to harm lungs, in a condition known as ‘ventilator-induced lung injury’ (VILI). So-called ‘lung-protective’ ventilator settings aiming at prevention of VILI have been shown to improve outcomes in patients with acute respiratory distress syndrome (ARDS), and, over the last few years, there has been increasing interest in possible benefit of lung-protective ventilation in patients under ventilation for reasons other than ARDS. Patients without ARDS could benefit from tidal volume reduction during mechanical ventilation. However, it is uncertain whether higher levels of positive end-expiratory pressure could benefit these patients as well. Finally, recent evidence suggests that patients without ARDS should receive low driving pressures during ventilation.

Partial Neuromuscular Blockade during Partial Ventilatory Support in Sedated Patients with High Tidal Volumes.

Controlled mechanical ventilation is used to deliver lung-protective ventilation in patients with acute respiratory distress syndrome. Despite recognized benefits, such as preserved diaphragm activity, partial support ventilation modes may be incompatible with lung-protective ventilation due to high Vt and high transpulmonary pressure. As an alternative to high-dose sedatives and controlled mechanical ventilation, pharmacologically induced neuromechanical uncoupling of the diaphragm should facilitate lung-protective ventilation under partial support modes. To investigate whether partial neuromuscular blockade can facilitate lung-protective ventilation while maintaining diaphragm activity under partial ventilatory support. In a proof-of-concept study, we enrolled 10 patients with lung injury and a Vt greater than 8 ml/kg under pressure support ventilation (PSV) and under sedation. After baseline measurements, rocuronium administration was titrated to a target Vt of 6 ml/kg during neurally adjusted ventilatory assist (NAVA). Thereafter, patients were ventilated in PSV and NAVA under continuous rocuronium infusion for 2 hours. Respiratory parameters, hemodynamic parameters, and blood gas values were measured. Rocuronium titration resulted in significant declines of Vt (mean ± SEM, 9.3 ± 0.6 to 5.6 ± 0.2 ml/kg; P < 0.0001), transpulmonary pressure (26.7 ± 2.5 to 10.7 ± 1.2 cm H2O; P < 0.0001), and diaphragm electrical activity (17.4 ± 2.3 to 4.5 ± 0.7 μV; P < 0.0001), and could be maintained under continuous rocuronium infusion. During titration, pH decreased (7.42 ± 0.02 to 7.35 ± 0.02; P < 0.0001), and mean arterial blood pressure increased (84 ± 6 to 99 ± 6 mm Hg; P = 0.0004), as did heart rate (83 ± 7 to 93 ± 8 beats/min; P = 0.0004). Partial neuromuscular blockade facilitates lung-protective ventilation during partial ventilatory support, while maintaining diaphragm activity, in sedated patients with lung injury.

Lung-protective Ventilation in Patients with Brain Injury: A Multicenter Cross-sectional Study and Questionnaire Survey in China.

Background:Over the years, the mechanical ventilation (MV) strategy has changed worldwide. The aim of the present study was to describe the ventilation practices, particularly lung-protective ventilation (LPV), among brain-injured patients in China.Methods:This study was a multicenter, 1-day, cross-sectional study in 47 Intensive Care Units (ICUs) across China. Mechanically ventilated patients (18 years and older) with brain injury in a participating ICU during the time of the study, including traumatic brain injury, stroke, postoperation with intracranial tumor, hypoxic-ischemic encephalopathy, intracranial infection, and idiopathic epilepsy, were enrolled. Demographic data, primary diagnoses, indications for MV, MV modes and settings, and prognoses on the 60th day were collected. Multivariable logistic analysis was used to assess factors that might affect the use of LPV.Results:A total of 104 patients were enrolled in the present study, 87 (83.7%) of whom were identified with severe brain injury based on a Glasgow Coma Scale ≤8 points. Synchronized intermittent mandatory ventilation (SIMV) was the most frequent ventilator mode, accounting for 46.2% of the entire cohort. The median tidal volume was set to 8.0 ml/kg (interquartile range [IQR], 7.0–8.9 ml/kg) of the predicted body weight; 50 (48.1%) patients received LPV. The median positive end-expiratory pressure (PEEP) was set to 5 cmH2O (IQR, 5–6 cmH2O). No PEEP values were higher than 10 cmH2O. Compared with partially mandatory ventilation, supportive and spontaneous ventilation practices were associated with LPV. There were no significant differences in mortality and MV duration between patients subjected to LPV and those were not.Conclusions:Among brain-injured patients in China, SIMV was the most frequent ventilation mode. Nearly one-half of the brain-injured patients received LPV. Patients under supportive and spontaneous ventilation were more likely to receive LPV.Trial Registration:ClinicalTrials.org NCT02517073 https://clinicaltrials.gov/ct2/show/NCT02517073.

Lung-protective ventilation initiated in the emergency department (LOV-ED): a study protocol for a quasi-experimental, before-after trial aimed at reducing pulmonary complications

IntroductionIn critically ill patients, acute respiratory distress syndrome (ARDS) and ventilator-associated conditions (VACs) are associated with increased mortality, survivor morbidity and healthcare resource utilisation. Studies conclusively demonstrate that initial ventilator...