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To evaluate the effects of four flow rates on the functional residual capacity (FRC) and pulmonary ventilation distribution while using a high-flow nasal cannula (HFNC).Our hypothesis is that flow rates below 1.5 L·kgsup-1/sup·minsup-1/suplead to FRC loss and respiratory distress.A single-center, prospective clinical study.Infants diagnosed with acute viral bronchiolitis were given HFNC.Through a prospective clinical study, the effects of four different flow rates, 2.0, 1.5, 1.0, and 0.5 L·kgsup-1/sup·minsup-1/sup, on FRC and the pulmonary ventilation pattern were evaluated using electrical impedance tomography. The impedance variation (delta Z), end-expiratory lung volume (EELZ), respiratory rate, heart rate, respiratory distress score, and saturation/fraction of inspired oxygen ratio (SpOsub2/sub/FsubI/subOsub2/sub), were also evaluated at each flow rate.Among the 11 infants included, There was a decrease in respiratory distress score at a flow rate of 1.5 L·kgsup-1/sup·minsup-1/sup(*p = 0.021), and at a flow rate of 2.0 L·kgsup-1/sup·minsup-1/sup(**p = 0.003) compared to 0.5 L·kgsup-1/sup·minsup-1/sup. There was also a small but significant increase in SpOsub2/sub/FiOsub2/subat flow rates of 1.5 (*p = 0.023), and 2.0 L·kgsup-1/sup·minsup-1/sup(**p = 0.008) compared to 0.5 L·kgsup-1/sup·minsup-1/sup. There were no other significant changes in the clinical parameters. In the global EELZ measurements, there was a significant increase under a flow rate of 2.0 L·kgsup-1/sup·minsup-1/supas compared to 0.5 L·kgsup-1/sup·minsup-1/sup(p = 0.03). In delta Z values, there were no significant variations between the different flow rates.The ∆EELZ increases at the highest flow rates were accompanied by decreased distress scores and improved oxygenation.

Introduction General anesthesia is associated with the development of atelectasis, which may affect lung ventilation. Electrical impedance tomography (EIT) is a noninvasive imaging tool that allows monitoring in real time the topographical changes in aeration and ventilation. Objective To evaluate the pattern of distribution of pulmonary ventilation through EIT before and after anesthesia induction in pediatric patients without lung disease undergoing nonthoracic surgery. Methods This was a prospective observational study including healthy children younger than 5 years who underwent nonthoracic surgery. Monitoring was performed continuously before and throughout the surgical period. Data analysis was divided into 5 periods: induction (spontaneous breathing, SB), ventilation-5min, ventilation-30min, ventilation-late and recovery-SB. In addition to demographic data, mechanical ventilation parameters were also collected. Ventilation impedance (Delta Z) and pulmonary ventilation distribution were analyzed cycle by cycle at the 5 periods. Results Twenty patients were included, and redistribution of ventilation from the posterior to the anterior region was observed with the beginning of mechanical ventilation: on average, the percentage ventilation distribution in the dorsal region decreased from 54%(IC95%:49–60%) to 49%(IC95%:44–54%). With the restoration of spontaneous breathing, ventilation in the posterior region was restored. Conclusion There were significant pulmonary changes observed during anesthesia and controlled mechanical ventilation in children younger than 5 years, mirroring the findings previously described adults. Monitoring these changes may contribute to guiding the individualized settings of the mechanical ventilator with the goal to prevent postoperative complications.

Background Strong spontaneous inspiratory efforts can be difficult to control and prohibit protective mechanical ventilation. Instead of using deep sedation and neuromuscular blockade, the authors hypothesized that perineural administration of lidocaine around the phrenic nerve would reduce tidal volume (VT) and peak transpulmonary pressure in spontaneously breathing patients with acute respiratory distress syndrome. Methods An established animal model of acute respiratory distress syndrome with six female pigs was used in a proof-of-concept study. The authors then evaluated this technique in nine mechanically ventilated patients under pressure support exhibiting driving pressure greater than 15 cm H2O or VT greater than 10 ml/kg of predicted body weight. Esophageal and transpulmonary pressures, electrical activity of the diaphragm, and electrical impedance tomography were measured in pigs and patients. Ultrasound imaging and a nerve stimulator were used to identify the phrenic nerve, and perineural lidocaine was administered sequentially around the left and right phrenic nerves. Results Results are presented as median [interquartile range, 25th to 75th percentiles]. In pigs, VT decreased from 7.4 ml/kg [7.2 to 8.4] to 5.9 ml/kg [5.5 to 6.6] (P < 0.001), as did peak transpulmonary pressure (25.8 cm H2O [20.2 to 27.2] to 17.7 cm H2O [13.8 to 18.8]; P < 0.001) and driving pressure (28.7 cm H2O [20.4 to 30.8] to 19.4 cm H2O [15.2 to 22.9]; P < 0.001). Ventilation in the most dependent part decreased from 29.3% [26.4 to 29.5] to 20.1% [15.3 to 20.8] (P < 0.001). In patients, VT decreased (8.2 ml/ kg [7.9 to 11.1] to 6.0 ml/ kg [5.7 to 6.7]; P < 0.001), as did driving pressure (24.7 cm H2O [20.4 to 34.5] to 18.4 cm H2O [16.8 to 20.7]; P < 0.001). Esophageal pressure, peak transpulmonary pressure, and electrical activity of the diaphragm also decreased. Dependent ventilation only slightly decreased from 11.5% [8.5 to 12.6] to 7.9% [5.3 to 8.6] (P = 0.005). Respiratory rate did not vary. Variables recovered 1 to 12.7 h [6.7 to 13.7] after phrenic nerve block. Conclusions Phrenic nerve block is feasible, lasts around 12 h, and reduces VT and driving pressure without changing respiratory rate in patients under assisted ventilation. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

Rationale: Mortality in acute respiratory distress syndrome (ARDS) has decreased after the adoption of lung-protective strategies. Lower VT, lower driving pressure (DP), lower respiratory rates (RR), and higher end-expiratory pressure have all been suggested as key components of lung protection strategies. A unifying theoretical explanation has been proposed that attributes lung injury to the energy transfer rate (mechanical power) from the ventilator to the patient, calculated froma combination of several ventilator variables. Objectives: To assess the impact of mechanical power on mortality in patients with ARDS as compared with that of primary ventilator variables such as the DP, VT, and RR. Methods: We obtained data on ventilatory variables and mechanical power from a pooled database of patients with ARDS who had participated in six randomized clinical trials of protective mechanical ventilation and one large observational cohort of patients with ARDS. The primary outcome was mortality at 28 days or 60 days. Measurements and Main Results: We included 4,549 patients (38% women; mean age, 55623 yr). The average mechanical power was 0.3260.14 J _ min21 _ kg21 of predicted body weight, the DP was 15.065.8 cm H2O, and the RR was 25.767.4 breaths/ min. The driving pressure, RR, and mechanical power were significant predictors of mortality in adjusted analyses. The impact of the DP on mortality was four times as large as that of the RR. Conclusions: Mechanical power was associated with mortality during controlled mechanical ventilation in ARDS, but a simpler model using only the DP and RR was equivalent.

Rationale: If the risk of ventilator-induced lung injury in acute respiratory distress syndrome (ARDS) is causally determined by driving pressure rather than by Vt, then the effect of ventilation w...

Importance Acute respiratory distress syndrome (ARDS) due to coronavirus disease 2019 (COVID-19) is associated with substantial mortality and use of health care resources. Dexamethasone use might attenuate lung injury in these patients. Objective To determine whether intravenous dexamethasone increases the number of ventilator-free days among patients with COVID-19–associated ARDS. Design, Setting, and Participants Multicenter, randomized, open-label, clinical trial conducted in 41 intensive care units (ICUs) in Brazil. Patients with COVID-19 and moderate to severe ARDS, according to the Berlin definition, were enrolled from April 17 to June 23, 2020. Final follow-up was completed on July 21, 2020. The trial was stopped early following publication of a related study before reaching the planned sample size of 350 patients. Interventions Twenty mg of dexamethasone intravenously daily for 5 days, 10 mg of dexamethasone daily for 5 days or until ICU discharge, plus standard care (n =151) or standard care alone (n = 148). Main Outcomes and Measures The primary outcome was ventilator-free days during the first 28 days, defined as being alive and free from mechanical ventilation. Secondary outcomes were all-cause mortality at 28 days, clinical status of patients at day 15 using a 6-point ordinal scale (ranging from 1, not hospitalized to 6, death), ICU-free days during the first 28 days, mechanical ventilation duration at 28 days, and Sequential Organ Failure Assessment (SOFA) scores (range, 0-24, with higher scores indicating greater organ dysfunction) at 48 hours, 72 hours, and 7 days. Results A total of 299 patients (mean [SD] age, 61 [14] years; 37% women) were enrolled and all completed follow-up. Patients randomized to the dexamethasone group had a mean 6.6 ventilator-free days (95% CI, 5.0-8.2) during the first 28 days vs 4.0 ventilator-free days (95% CI, 2.9-5.4) in the standard care group (difference, 2.26; 95% CI, 0.2-4.38;P = .04). At 7 days, patients in the dexamethasone group had a mean SOFA score of 6.1 (95% CI, 5.5-6.7) vs 7.5 (95% CI, 6.9-8.1) in the standard care group (difference, −1.16; 95% CI, −1.94 to −0.38;P= .004). There was no significant difference in the prespecified secondary outcomes of all-cause mortality at 28 days, ICU-free days during the first 28 days, mechanical ventilation duration at 28 days, or the 6-point ordinal scale at 15 days. Thirty-three patients (21.9%) in the dexamethasone group vs 43 (29.1%) in the standard care group experienced secondary infections, 47 (31.1%) vs 42 (28.3%) needed insulin for glucose control, and 5 (3.3%) vs 9 (6.1%) experienced other serious adverse events. Conclusions and Relevance Among patients with COVID-19 and moderate or severe ARDS, use of intravenous dexamethasone plus standard care compared with standard care alone resulted in a statistically significant increase in the number of ventilator-free days (days alive and free of mechanical ventilation) over 28 days. Trial Registration ClinicalTrials.gov Identifier:NCT04327401

BACKGROUND: To examine the influence of positive end-expiratory pressure (PEEP) settings on lung mechanics and oxygenation in elderly patients undergoing thoracoscopic surgery. METHODS: One hundred patients aged >65 years were randomly allocated into either the PEEP(5) or the electrical impedance tomography (EIT) group (PEEP(EIT)). Each group underwent volume-controlled ventilation (tidal volume 6 mL/kg predicted body weight) with the PEEP either fixed at 5 cmH(2)O or set at an individualized EIT setting. The primary endpoint was the ratio of the arterial oxygen partial pressure to the fractional inspired oxygen (PaO(2)/FiO(2)). The secondary endpoints included the driving pressure, and dynamic respiratory system compliance (C(dyn)). Other outcomes, such as the mean airway pressure (P(mean)), mean arterial pressure (MAP), lung complications and the length of hospital stay were explored. RESULTS: The optimal PEEP set by EIT was significantly higher (range from 9–13 cmH(2)O) than the fixed PEEP. PaO(2)/FiO(2) was 47 mmHg higher (95% CI: 7–86 mmHg; P=0.021), C(dyn) was 4.3 mL/cmH(2)O higher (95% CI: 2.1–6.7 cmH(2)O; P

RESUMO Objetivo: A infecção causada pelo coronavírus da síndrome respiratória aguda grave 2 (SARS-CoV-2) disseminou-se por todo o mundo e foi categorizada como pandemia. As manifestações mais comuns da infecção pelo SARS-CoV-2 (doença pelo coronavírus 2019 - COVID-19) se referem a uma pneumonia viral com graus variáveis de comprometimento respiratório e até 40% dos pacientes hospitalizados, que podem desenvolver uma síndrome do desconforto respiratório agudo. Diferentes ensaios clínicos avaliaram o papel dos corticosteroides na síndrome do desconforto respiratório agudo não relacionada com COVID-19, obtendo resultados conflitantes. Delineamos o presente estudo para avaliar a eficácia da administração endovenosa precoce de dexametasona no número de dias vivo e sem ventilação mecânica nos 28 dias após a randomização, em pacientes adultos com quadro moderado ou grave de síndrome do desconforto respiratório agudo causada por COVID-19 provável ou confirmada. Métodos: Este é um ensaio pragmático, prospectivo, randomizado, estratificado, multicêntrico, aberto e controlado que incluirá 350 pacientes com quadro inicial (menos de 48 horas antes da randomização) de síndrome do desconforto respiratório agudo moderada ou grave, definida segundo os critérios de Berlim, causada por COVID-19. Os pacientes elegíveis serão alocados de forma aleatória para tratamento padrão mais dexametasona (Grupo Intervenção) ou tratamento padrão sem dexametasona (Grupo Controle). Os pacientes no Grupo Intervenção receberão dexametasona 20mg por via endovenosa uma vez ao dia, por 5 dias, e, a seguir, dexametasona por via endovenosa 10mg ao dia por mais 5 dias, ou até receber alta da unidade de terapia intensiva, o que ocorrer antes. O desfecho primário será o número de dias livres de ventilação mecânica nos 28 dias após a randomização, definido como o número de dias vivo e livres de ventilação mecânica invasiva. Os desfechos secundários serão a taxa de mortalidade por todas as causas no dia 28, a condição clínica no dia 15 avaliada com utilização de uma escala ordinal de seis níveis, a duração da ventilação mecânica desde a randomização até o dia 28, a avaliação com o Sequential Organ Failure Assessment Score após 48 horas, 72 horas e 7 dias, e o número de dias fora da unidade de terapia intensiva nos 28 dias após a randomização. Abstract Objective: The infection caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads worldwide and is considered a pandemic. The most common manifestation of SARS-CoV-2 infection (coronavirus disease 2019 - COVID-19) is viral pneumonia with varying degrees of respiratory compromise and up to 40% of hospitalized patients might develop acute respiratory distress syndrome. Several clinical trials evaluated the role of corticosteroids in non-COVID-19 acute respiratory distress syndrome with conflicting results. We designed a trial to evaluate the effectiveness of early intravenous dexamethasone administration on the number of days alive and free of mechanical ventilation within 28 days after randomization in adult patients with moderate or severe acute respiratory distress syndrome due to confirmed or probable COVID-19. Methods: This is a pragmatic, prospective, randomized, stratified, multicenter, open-label, controlled trial including 350 patients with early-onset (less than 48 hours before randomization) moderate or severe acute respiratory distress syndrome, defined by the Berlin criteria, due to COVID-19. Eligible patients will be randomly allocated to either standard treatment plus dexamethasone (Intervention Group) or standard treatment without dexamethasone (Control Group). Patients in the intervention group will receive dexamethasone 20mg intravenous once daily for 5 days, followed by dexamethasone 10mg IV once daily for additional 5 days or until intensive care unit discharge, whichever occurs first. The primary outcome is ventilator-free days within 28 days after randomization, defined as days alive and free from invasive mechanical ventilation. Secondary outcomes are all-cause mortality rates at day 28, evaluation of the clinical status at day 15 assessed with a 6-level ordinal scale, mechanical ventilation duration from randomization to day 28, Sequential Organ Failure Assessment Score evaluation at 48 hours, 72 hours and 7 days and intensive care unit -free days within 28.

Objective: To develop and apply a competency-based test to assess learning among internal medicine residents during a respiratory ICU rotation at a university hospital. Methods: We developed a test comprising 19 multiple-choice questions regarding knowledge of mechanical ventilation (MV) and 4 self-assessment questions regarding the degree of confidence in the management of MV. The test was applied on the first and last day of a 30-day respiratory ICU rotation (pre-rotation and post-rotation, respectively). During the rotation, the residents had lectures, underwent simulator training, and shadowed physicians on daily bedside rounds focused on teaching MV management. Results: Fifty residents completed the test at both time points. The mean score increased from 6.9 ± 1.2 (pre-rotation) to 8.6 ± 0.8 (post-rotation; p < 0.001). On questions regarding the approach to hypoxemia, the recognition of patient-ventilator asynchrony, and the recognition of risk factors for extubation failure, the post-rotation scores were significantly higher than the pre-rotation scores. Confidence in airway management increased from 6% before the rotation to 22% after the rotation (p = 0.02), whereas confidence in making the initial MV settings increased from 31% to 96% (p < 0.001) and confidence in adjusting the ventilator modes increased from 23% to 77% (p < 0.001). Conclusions: We developed a competency-based test to assess knowledge of MV among residents before and after an rotation in a respiratory ICU. Resident performance increased significantly after the rotation, as did their confidence in caring for patients on MV. RESUMO Objetivo: Desenvolver e aplicar um teste baseado em competências para avaliar o aprendizado de residentes de clínica médica em estágio na UTI respiratória de um hospital universitário. Métodos: Desenvolvemos um teste com 19 questões de múltipla escolha sobre conhecimento em ventilação mecânica (VM) e 4 questões de autoavaliação sobre o nível de confiança no manejo da VM. Os testes foram aplicados no primeiro (pré-estágio) e no último dia (pós-estágio) do estágio de 30 dias na UTI respiratória. Durante o estágio, os residentes tiveram aulas teóricas, treinamento com simulador e visitas diárias à beira do leito focadas no ensino de VM. Resultados: Cinquenta residentes completaram o teste nos dois momentos. A média de pontuação (0-10 pontos) aumentou de 6,9 ± 1,2 no pré-estágio para 8,6 ± 0,8 no pós-estágio (p < 0,001). Observamos um aumento significativo no pós-estágio comparado com o pré-estágio em questões sobre abordagem da hipoxemia, reconhecimento da assincronia paciente-ventilador e reconhecimento de fatores de risco para falha de extubação. A confiança na abordagem de vias aéreas aumentou de 6% para 22% ao final do estágio (p = 0,02). A confiança no ajuste inicial da VM subiu de 31% para 96% (p < 0,001), e a confiança no ajuste dos modos ventilatórios aumentou de 23% para 77% (p < 0,001). Conclusões: Desenvolvemos um teste baseado em competências para avaliar o conhecimento sobre VM entre residentes antes e depois de um estágio em UTI respiratória. O desempenho dos residentes ao final do estágio aumentou significativamente, assim como sua confiança para cuidar de pacientes sob VM.

Background The coronavirus disease (COVID-19) pandemic has brought significant challenges worldwide, with high mortality, increased use of hospital resources, and the collapse of healthcare systems. We aimed to describe the clinical outcomes of critically ill COVID-19 patients and assess the impact on the use of hospital resources and compare with critically ill medical patients without COVID-19. Methods and findings In this retrospective cohort study, we included patients diagnosed with COVID-19 admitted to a private ICU in Sao Paulo, Brazil from March to June 2020. We compared these patients with those admitted to the unit in the same period of the previous year. A total of 212 consecutive patients with a confirmed diagnosis of COVID-19 were compared with 185 medical patients from the previous year. Patients with COVID-19 were more frequently males (76% vs. 56%, p Conclusions COVID-19 required more hospital resources, including invasive and non-invasive ventilation, had a longer duration of mechanical ventilation, and a more prolonged ICU and hospital length of stay. There was no difference in all-cause mortality at 28 and 60 days, suggesting that health systems preparedness be an important determinant of clinical outcomes.

In acute respiratory distress syndrome (ARDS), atelectatic solid-like lung tissue impairs transmission of negative swings in pleural pressure (Ppl) that result from diaphragmatic contraction. The localization of more negative Ppl proportionally increases dependent lung stretch by drawing gas either from other lung regions (e.g., nondependent lung [pendelluft]) or from the ventilator. Lowering the level of spontaneous effort and/or converting solid-like to fluid-like lung might render spontaneous effort noninjurious.To determine whether spontaneous effort increases dependent lung injury, and whether such injury would be reduced by recruiting atelectatic solid-like lung with positive end-expiratory pressure (PEEP).Established models of severe ARDS (rabbit, pig) were used. Regional histology (rabbit), inflammation (positron emission tomography; pig), regional inspiratory Ppl (intrabronchial balloon manometry), and stretch (electrical impedance tomography; pig) were measured. Respiratory drive was evaluated in 11 patients with ARDS.Although injury during muscle paralysis was predominantly in nondependent and middle lung regions at low (vs. high) PEEP, strong inspiratory effort increased injury (indicated by positron emission tomography and histology) in dependent lung. Stronger effort (vs. muscle paralysis) caused local overstretch and greater tidal recruitment in dependent lung, where more negative Ppl was localized and greater stretch was generated. In contrast, high PEEP minimized lung injury by more uniformly distributing negative Ppl, and lowering the magnitude of spontaneous effort (i.e., deflection in esophageal pressure observed in rabbits, pigs, and patients).Strong effort increased dependent lung injury, where higher local lung stress and stretch was generated; effort-dependent lung injury was minimized by high PEEP in severe ARDS, which may offset need for paralysis.

Rationale: In acute respiratory distress syndrome (ARDS), atelectatic solid-like lung tissue impairs transmission of negative swings in pleural pressure (Ppl) that result from diaphragmatic contraction. The localization of more negative Ppl proportionally increases dependent lung stretch by drawing gas either from other lung regions (e.g., nondependent lung [pendelluft]) or from the ventilator. Lowering the level of spontaneous effort and/or converting solid-like to fluid-like lung might render spontaneous effort noninjurious. Objectives: To determine whether spontaneous effort increases dependent lung injury, and whether such injury would be reduced by recruiting atelectatic solid-like lung with positive end-expiratory pressure (PEEP). Methods: Established models of severe ARDS (rabbit, pig) were used. Regional histology (rabbit), inflammation (positron emission tomography; pig), regional inspiratory Ppl (intrabronchial balloon manometry), and stretch (electrical impedance tomography; pig) were measured. Respiratory drive was evaluated in 11 patients with ARDS. Measurements and Main Results: Although injury during muscle paralysis was predominantly in nondependent and middle lung regions at low (vs. high) PEEP, strong inspiratory effort increased injury (indicated by positron emission tomography and histology) in dependent lung. Stronger effort (vs. muscle paralysis) caused local overstretch and greater tidal recruitment in dependent lung, where more negative Ppl was localized and greater stretch was generated. In contrast, high PEEP minimized lung injury by more uniformly distributing negative Ppl, and lowering the magnitude of spontaneous effort (i.e., deflection in esophageal pressure observed in rabbits, pigs, and patients). Conclusions: Strong effort increased dependent lung injury, where higher local lung stress and stretch was generated; effort-dependent lung injury was minimized by high PEEP in severe ARDS, which may offset need for paralysis.

Background Electrical impedance tomography (EIT) is a noninvasive imaging method that identifies changes in air and blood volume based on thoracic impedance changes. Recently, there has been growing interest in EIT to measure stroke volume (SV). The objectives of this study are as follows: (1) to evaluate the ability of systolic impedance variations (ΔZsys) to track changes in SV in relation to a baseline condition; (2) to assess the relationship of ΔZsys and SV in experimental subjects; and (3) to identify the influence of body dimensions on the relationship between ΔZsys and SV. Methods Twelve Agroceres pigs were instrumented with transpulmonary thermodilution catheter and EIT and were mechanically ventilated in a random order using different settings of tidal volume (VT) and positive end-expiratory pressure (PEEP): VT 10 mL·kg and PEEP 10 cm H2O, VT 10 mL·kg and PEEP 5 cm H2O, VT 6 mL·kg and PEEP 10 cm H2O, and VT 6 mL·kg and PEEP 5 cm H2O. After baseline data collection, subjects were submitted to hemorrhagic shock and successive fluid challenges. Results A total of 204 paired measurements of SV and ΔZsys were obtained. The 4-quadrant plot showed acceptable trending ability with a concordance rate of 91.2%. Changes in ΔZsys after fluid challenges presented an area under the curve of 0.83 (95% confidence interval, 0.74-0.92) to evaluate SV changes. Conversely, the linear association between ΔZsys and SV was poor, with R from linear mixed model of 0.35. Adding information on body dimensions improved the linear association between ΔZsys and SV up to R from linear mixed model of 0.85. Conclusions EIT showed good trending ability and is a promising hemodynamic monitoring tool. Measurements of absolute SV require that body dimensions be taken into account.

Background Patients with acute decompensation of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) admitted to intensive care unit (ICU) have high in-hospital mortality. We hypothesized that pulmonary hypertension (PH) severity, measured by a simplified version of European Society of Cardiology/European Respiratory Society (ESC/ERS) risk assessment, and the severity of organ dysfunction upon ICU admission, measured by sequential organ failure assessment score (SOFA) were associated with in-hospital mortality in decompensated patients with PAH and CTEPH. We also described clinical and laboratory variables during ICU stay. Methods Observational study including adults with decompensated PAH or CTEPH with unplanned ICU admission between 2014 and 2019. Multivariate logistic regression models were used to evaluate the association of ESC/ERS risk assessment and SOFA score with in-hospital mortality. ESC/ERS risk assessment and SOFA score were included in a decision tree to predict in-hospital mortality. Results 73 patients were included. In-hospital mortality was 41.1%. ESC/ERS high-risk group (adjusted odds ratio = 95.52) and SOFA score (adjusted odds ratio = 1.80) were associated with in-hospital mortality. The decision tree identified four groups with in-hospital mortality between 8.1% and 100%. Nonsurvivors had a lower central venous oxygen saturation, higher arterial lactate and higher brain natriuretic peptide in the end of first week in the ICU. Conclusions High-risk on a simplified version of ERS/ESC risk assessment and SOFA score upon ICU admission are associate with in-hospital mortality. A decision tree based on ESC/ERS risk assessment and SOFA score identifies four groups with in-hospital mortality between 8.1% and 100%.

RATIONALE AND OBJECTIVES: Pulmonary atelectasis presumably promotes and facilitates lung injury. However, data are limited on its direct and remote relation to inflammation. We aimed to assess regional 2-deoxy-2-[(18)F]-fluoro-D-glucose ((18)F-FDG) kinetics representative of inflammation in atelectatic and normally aerated regions in models of early lung injury. MATERIALS AND METHODS: We studied supine sheep in four groups: Permissive Atelectasis (n=6)- 16h protective tidal volume (V(T)) and zero positive end-expiratory pressure; Mild (n=5) and Moderate Endotoxemia (n=6)- 20–24h protective ventilation and intravenous lipopolysaccharide (Mild=2.5 and Moderate=10.0 ng/kg/min), and Surfactant Depletion (n=6)- saline lung lavage and 4h high V(T). Measurements performed immediately after anesthesia induction served as controls (n=8). Atelectasis was defined as regions of gas fraction

Background Despite a robust physiological rationale, recruitment manoeuvres with PEEP titration were associated with harm in the Alveolar Recruitment for Acute Respiratory Distress Syndrome Trial (ART). We sought to investigate the potential heterogeneity in treatment effects in patients enrolled in the ART, using a machine learning approach. Methods The primary outcome was hospital mortality. Patients were clustered using baseline clinical and physiological data using the k-means for mixed large data method. The heterogeneity in treatment effect between clusters was investigated using Bayesian methods. We further investigated whether baseline driving pressure could modulate the association between treatment arm, cluster, and mortality. Results Data from all 1010 patients enrolled in the ART were analysed. Partitioning suggested that three clusters were present in the ART population. The largest cluster (Cluster 1) was characterised by patients with pneumonia and requiring vasopressor support. Recruitment manoeuvres with PEEP titration were associated with higher mortality in Cluster 1 (probability of harm of >98%), but this association was absent in Clusters 2 and 3 (probability of harm of 45% and 68%, respectively). Higher baseline driving pressure was associated with a progressive reduction in the association between alveolar recruitment with PEEP titration and mortality. Conclusions Recruitment manoeuvre with PEEP titration may be harmful in acute respiratory distress syndrome (ARDS) patients with pneumonia or requiring vasopressor support. Driving pressure appears to modulate the association between the ART study intervention, aetiology of ARDS, and mortality. This machine learning approach may help tailor future RCTs. Clinical trial registration NCT01374022.

Noninvasive ventilation (NIV) is commonly used to prevent endotracheal intubation in patients with acute respiratory distress syndrome (ARDS). Patients with hypoxemic acute respiratory failure who fail an NIV trial carry a worse prognosis as compared to those who succeed. Additional factors are also knowingly associated with worse outcomes: higher values of ICU severity score, presence of severe sepsis, and lower ratio of arterial oxygen tension to fraction of inspired oxygen. However, it is still unclear whether NIV failure is responsible for the worse prognosis or if it is merely a marker of the underlying disease severity. There is therefore an ongoing debate as to whether and which ARDS patients are good candidates to an NIV trial. In a recent paper published in JAMA, “Effect of Noninvasive Ventilation Delivered by Helmet vs. Face Mask on the Rate of Endotracheal Intubation in Patients with Acute Respiratory Distress Syndrome: A Randomized Clinical Trial”, Patel et al. evaluated ARDS patients submitted to NIV and drew attention to the importance of the NIV interface. We discussed their interesting findings focusing also on the ventilator settings and on the current barriers to lung protective ventilation in ARDS patients during NIV.

Purpose: Extracorporeal membrane oxygenation (ECMO) is a rescue therapy for patients with acute respiratory distress syndrome (ARDS). The aim of this study was to evaluate associations between ventilatory settings during ECMO for refractory hypoxemia and outcome in ARDS patients. Methods: In this individual patient data meta-analysis of observational studies in adult ARDS patients receiving ECMO for refractory hypoxemia, a time-dependent frailty model was used to determine which ventilator settings in the first 3 days of ECMO had an independent association with in-hospital mortality. Results: Nine studies including 545 patients were included. Initiation of ECMO was accompanied by significant decreases in tidal volume size, positive end-expiratory pressure (PEEP), plateau pressure, and driving pressure (plateau pressure − PEEP) levels, and respiratory rate and minute ventilation, and resulted in higher PaO2/FiO2, higher arterial pH and lower PaCO2 levels. Higher age, male gender and lower body mass index were independently associated with mortality. Driving pressure was the only ventilatory parameter during ECMO that showed an independent association with in-hospital mortality [adjusted HR, 1.06 (95 % CI, 1.03–1.10)]. Conclusion: In this series of ARDS patients receiving ECMO for refractory hypoxemia, driving pressure during ECMO was the only ventilator setting that showed an independent association with in-hospital mortality. © 2016, Springer-Verlag Berlin Heidelberg and ESICM.

Objective: The aim of this study was to explore the factors associated with blood oxygen partial pressure and carbon dioxide partial pressure. Methods: The factors associated with oxygen - and carbon dioxide regulation were investigated in an apneic pig model under veno-venous extracorporeal membrane oxygenation support. A predefined sequence of blood and sweep flows was tested. Results: Oxygenation was mainly associated with extracorporeal membrane oxygenation blood flow (beta coefficient = 0.036mmHg/mL/min), cardiac output (beta coefficient = -11.970mmHg/L/min) and pulmonary shunting (beta coefficient = -0.232mmHg/%). Furthermore, the initial oxygen partial pressure and carbon dioxide partial pressure measurements were also associated with oxygenation, with beta coefficients of 0.160 and 0.442mmHg/mmHg, respectively. Carbon dioxide partial pressure was associated with cardiac output (beta coefficient = 3.578mmHg/L/min), sweep gas flow (beta coefficient = -2.635mmHg/L/min), temperature (beta coefficient = 4.514mmHg/oC), initial pH (beta coefficient = -66.065mmHg/0.01 unit) and hemoglobin (beta coefficient = 6.635mmHg/g/dL). Conclusion: In conclusion, elevations in blood and sweep gas flows in an apneic veno-venous extracorporeal membrane oxygenation model resulted in an increase in oxygen partial pressure and a reduction in carbon dioxide partial pressure 2, respectively. Furthermore, without the possibility of causal inference, oxygen partial pressure was negatively associated with pulmonary shunting and cardiac output, and carbon dioxide partial pressure was positively associated with cardiac output, core temperature and initial hemoglobin.

Background Mounier-Kuhn syndrome or congenital tracheobronchomegaly is a rare disease characterized by dilation of the trachea and the main bronchi within the thoracic cavity. The predominant signs and symptoms of the disease include coughing, purulent and abundant expectoration, dyspnea, snoring, wheezing, and recurrent respiratory infection. Symptoms of the disease in some patients are believed to be pathological manifestations arising due to resident tracheobronchomalacia. Although treatment options used for the management of this disease include inhaled bronchodilators, corticosteroids, and hypertonic solution, there is no consensus on the treatment. The use of continuous positive airway pressure (CPAP) has been reported as a potential therapeutic option for tracheobronchomalacia, but no prospective studies have demonstrated its efficacy in this condition. Objective The purpose of this is to identify the presence of tracheobronchomalacia and an optimal CPAP pressure that reduces the tracheobronchial collapse in patients with Mounier-Kuhn syndrome and to analyze the repercussion in pulmonary ventilation. In parallel, we aim to evaluate the prevalence of obstructive sleep apnea/hypopnea syndrome. Methods This interventional, open-label, single-arm clinical trial will enroll patients who are diagnosed Mounier-Kuhn syndrome. Patient evaluation will be conducted in an outpatient clinic and involve 3 visits. Visit 1 will involve the collection and registration of social demographic, clinical, and functional data. Visit 2 will entail polysomnography, bronchoscopy for the evaluation of tracheobronchomalacia, titration of the optimal pressure that reduces the degree of collapse of the airway, and electrical impedance tomography. In visit 3, patients exhibiting a reduction in collapse areas will be requested to undergo chest computed tomography during inspiration and forced expiration with and without positive pressure (titrated to determine optimal CPAP pressure). Results This protocol is a doctorate project. The project was submitted to the institutional review board on January 24, 2017, and approval was granted on February 2, 2017 (Brazilian Research database number CAAE 64001317.4.000.0068). Patient evaluations started in April 2018. Planned recruitment is based on volunteers’ availability and clinical stability, and interventions will be conducted at least once a month to finish the project at the end of 2020. A preliminary analysis of each case will be performed after each intervention, but detailed results are expected to be reported in the first quarter of 2021. Conclusions There is no consensus on the best treatment options for managing Mounier-Kuhn syndrome. The use of positive pressure could maintain patency of the collapsed airways, functioning as a “pneumatic stent” to reduce the degree of airflow obstruction. This, in turn, could promote mobilization of thoracic secretion and improve pulmonary ventilation. Trial Registration ClinicalTrails.gov NCT03101059; https://clinicaltrials.gov/ct2/show/NCT03101059. International Registered Report Identifier (IRRID) DERR1-10.2196/14786

Esophageal manometry is the clinically available method to estimate pleural pressure, thus enabling calculation of transpulmonary pressure (Pl). However, many concerns make it uncertain in which lung region esophageal manometry reflects local Pl.To determine the accuracy of esophageal pressure (Pes) and in which regions esophageal manometry reflects pleural pressure (Ppl) and Pl; to assess whether lung stress in nondependent regions can be estimated at end-inspiration from Pl.In lung-injured pigs (n = 6) and human cadavers (n = 3), Pes was measured across a range of positive end-expiratory pressure, together with directly measured Ppl in nondependent and dependent pleural regions. All measurements were obtained with minimal nonstressed volumes in the pleural sensors and esophageal balloons. Expiratory and inspiratory Pl was calculated by subtracting local Ppl or Pes from airway pressure; inspiratory Pl was also estimated by subtracting Ppl (calculated from chest wall and respiratory system elastance) from the airway plateau pressure.In pigs and human cadavers, expiratory and inspiratory Pl using Pes closely reflected values in dependent to middle lung (adjacent to the esophagus). Inspiratory Pl estimated from elastance ratio reflected the directly measured nondependent values.These data support the use of esophageal manometry in acute respiratory distress syndrome. Assuming correct calibration, expiratory Pl derived from Pes reflects Pl in dependent to middle lung, where atelectasis usually predominates; inspiratory Pl estimated from elastance ratio may indicate the highest level of lung stress in nondependent "baby" lung, where it is vulnerable to ventilator-induced lung injury.

Objective:It is known that ventilator-induced lung injury causes increased pulmonary inflammation. It has been suggested that one of the underlying mechanisms may be strain. The aim of this study was to investigate whether lung regional strain correlates with regional inflammation in a porcine model

Acute respiratory distress syndrome (ARDS) is a clinical entity that acutely affects the lung parenchyma, and is characterized by diffuse alveolar damage and increased pulmonary vascular permeability. Currently, computed tomography (CT) is commonly used for classifying and prognosticating ARDS. However, performing this examination in critically ill patients is complex, due to the need to transfer these patients to the CT room. Fortunately, new technologies have been developed that allow the monitoring of patients at the bedside. Electrical impedance tomography (EIT) is a monitoring tool that allows one to evaluate at the bedside the distribution of pulmonary ventilation continuously, in real time, and which has proven to be useful in optimizing mechanical ventilation parameters in critically ill patients. Several clinical applications of EIT have been developed during the last years and the technique has been generating increasing interest among researchers. However, among clinicians, there is still a lack of knowledge regarding the technical principles of EIT and potential applications in ARDS patients. The aim of this review is to present the characteristics, technical concepts, and clinical applications of EIT, which may allow better monitoring of lung function during ARDS.

BACKGROUND Mechanical-ventilation strategies that use lower end-inspiratory (plateau) airway pressures, lower tidal volumes (V T ), and higher positive end-expiratory pressures (PEEPs) can improve survival in patients with the acute respiratory distress syndrome (ARDS), but the relative importance of each of these components is uncertain. Because respiratory-system compliance (C RS ) is strongly related to the volume of aerated remaining functional lung during disease (termed functional lung size), we hypothesized that driving pressure (ΔP = V T /C RS ), in which V T is intrinsically normalized to functional lung size (instead of predicted lung size in healthy persons), would be an index more strongly associated with survival than V T or PEEP in patients who are not actively breathing. METHODS Using a statistical tool known as multilevel mediation analysis to analyze individual data from 3562 patients with ARDS enrolled in nine previously reported randomized trials, we examined ΔP as an independent variable associated with survival. In the mediation analysis, we estimated the isolated effects of changes in ΔP resulting from randomized ventilator settings while minimizing confounding due to the baseline severity of lung disease. RESULTS Among ventilation variables, ΔP was most strongly associated with survival. A 1-SD increment in ΔP (approximately 7 cm of water) was associated with increased mortality (relative risk, 1.41; 95% confidence interval [CI], 1.31 to 1.51; P

Background Controlling blood pH during acute ventilatory failure and hypercapnia in individuals suffering from severe acute kidney injury (AKI) and undergoing continuous renal replacement therapy (CRRT) is of paramount importance in critical care settings. In this situation, the optimal concentration of sodium bicarbonate in the dialysate is still an unsolved question in critical care since high concentrations may worsen carbon dioxide levels and low concentrations may not be as effective in controlling pH. Methods We performed a randomized, non-blinded, experimental study. AKI was induced in 12 female pigs via renal hilum ligation and hypoventilation by reducing the tidal volume during mechanical ventilation with the goal of achieving a pH between 7.10–7.15. After achieving the target pH, animals were randomized to undergo isovolemic hemodialysis with one of two bicarbonate concentrations in the dialysate (40 mEq/L [group 40] vs. 20 mEq/L [group 20]). Results Hemodynamic, respiratory, and laboratory data were collected. The median pH value at CRRT initiation was 7.14 [7.12, 7.15] in group 20 and 7.13 [7.09, 7.14] in group 40 (P = ns). The median baseline PaCO2 was 74 [72, 81] mmHg in group 20 vs. 79 [63, 85] mmHg in group 40 (P = ns). After 3 h of CRRT, the pH value was 7.05 [6.95, 7.09] in group 20 and 7.12 [7.1, 7.14] in group 40 (P

Background Utilization of extracorporeal membrane oxygenation (ECMO) has increased worldwide, but its use remains restricted to severely ill patients, and few referral centers are properly structured to offer this support. Inter-hospital transfer of patients on ECMO support can be life-threatening. In this study, we report a single-center experience and a systematic review of the available published data on complications and mortality associated with ECMO transportation. Methods We reported single-center data regarding complications and mortality associated with the transportation of patients on ECMO support. Additionally, we searched multiple databases for case series, observational studies, and randomized controlled trials regarding mortality of patients transferred on ECMO support. Results were analyzed independently for pediatric (under 12 years old) and adult populations. We pooled mortality rates using a random-effects model. Complications and transportation data were also described. Results A total of 38 manuscripts, including our series, were included in the final analysis, totaling 1481 patients transported on ECMO support. A total of 951 patients survived to hospital discharge. The pooled survival rates for adult and pediatric patients were 62% (95% CI 57–68) and 68% (95% CI 60–75), respectively. Two deaths occurred during patient transportation. No other complication resulting in adverse outcome was reported. Conclusion Using the available pooled data, we found that patient transfer to a referral institution while on ECMO support seems to be safe and adds no significant risk of mortality to ECMO patients. Electronic supplementary material The online version of this article (doi:10.1186/s13613-016-0232-7) contains supplementary material, which is available to authorized users.

In patients with severe respiratory failure, either hypoxemic or hypercapnic, life support with mechanical ventilation alone can be insufficient to meet their needs, especially if one tries to avoid ventilator settings that can cause injury to the lungs. In those patients, extracorporeal membrane oxygenation (ECMO), which is also very effective in removing carbon dioxide from the blood, can provide life support, allowing the application of protective lung ventilation. In this review article, we aim to explore some of the most relevant aspects of using ECMO for respiratory support. We discuss the history of respiratory support using ECMO in adults, as well as the clinical evidence; costs; indications; installation of the equipment; ventilator settings; daily care of the patient and the system; common troubleshooting; weaning; and discontinuation. RESUMO Em pacientes com insuficiência respiratória grave (hipoxêmica ou hipercápnica), o suporte somente com ventilação mecânica pode ser insuficiente para suas necessidades, especialmente quando se tenta evitar o uso de parâmetros ventilatórios que possam causar danos aos pulmões. Nesses pacientes, extracorporeal membrane oxygenation (ECMO, oxigenação extracorpórea por membrana), que também é muito eficaz na remoção de dióxido de carbono do sangue, pode manter a vida, permitindo o uso de ventilação pulmonar protetora. No presente artigo de revisão, objetivamos explorar alguns dos aspectos mais relevantes do suporte respiratório por ECMO. Discutimos a história do suporte respiratório por ECMO em adultos; evidências clínicas; custos; indicações; instalação do equipamento; parâmetros ventilatórios; cuidado diário do paciente e do sistema; solução de problemas comuns; desmame e descontinuação.

Objective: To evaluate the satisfaction of the intensive care unit staff with a computerized physician order entry and to compare the concept of the computerized physician order entry relevance among intensive care unit healthcare workers. Methods: We performed a cross-sectional survey to assess the satisfaction of the intensive care unit staff with the computerized physician order entry in a 30-bed medical/surgical adult intensive care unit using a self-administered questionnaire. The questions used for grading satisfaction levels were answered according to a numerical scale that ranged from 1 point (low satisfaction) to 10 points (high satisfaction). Results: The majority of the respondents (n=250) were female (66%) between the ages of 30 and 35 years of age (69%). The overall satisfaction with the computerized physician order entry scored 5.74±2.14 points. The satisfaction was lower among physicians (n=42) than among nurses, nurse technicians, respiratory therapists, clinical pharmacists and diet specialists (4.62±1.79 versus 5.97±2.14, p

Bronchial stenosis can impair regional lung ventilation by causing abnormal, asymmetric airflow limitation. Electrical impedance tomography (EIT) is an imaging technique that allows the assessment of regional lung ventilation and therefore complements the functional assessment of the lungs. We report the case of a patient with left unilateral bronchial stenosis and a history of tuberculosis, in whom regional lung ventilation was assessed by EIT. The EIT results were compared with those obtained by ventilation/perfusion radionuclide imaging. The patient was using nasal continuous positive airway pressure (CPAP) for the treatment of obstructive sleep apnea syndrome. Therefore, we studied the effects of postural changes and of the use of nasal CPAP. The EIT revealed heterogeneous distribution of regional lung ventilation, the ventilation being higher in the right lung, and this distribution was influenced by postural changes and CPAP use. The EIT assessment of regional lung ventilation produced results similar to those obtained with the radionuclide imaging technique and had the advantage of providing a dynamic evaluation without radiation exposure.

1 Attending Physician, Department of Cardiorespiratory Diseases, Heart Institute, University of Sao Paulo School of Medicine Hospital das Clinicas, Sao Paulo, Brazil 2 Attending Physician, Respiratory Intensive Care Unit, University of Sao Paulo School of Medicine Hospital das Clinicas, Sao Paulo, Brazil 3 Attending Physician, Department of Cardiorespiratory Diseases, Heart Institute, University of Sao Paulo School of Medicine Hospital das Clinicas, Sao Paulo, Brazil Tracheobronchomalacia (TBM) is a disorder caused by weakness of the tracheal and bronchial walls, together with softening of the supporting cartilage, resulting in excessive expiratory collapse. (1) Although some individuals with TBM are asymptomatic, others present with symptoms such as dyspnea, hemoptysis, wheezing, and chronic cough.(1-3) Because the symptoms are nonspecific, TBM can be easily overlooked or misdiagnosed as other obstructive airway diseases, including asthma and COPD.(4) In TBM patients with acute respiratory failure, noninvasive ventilation is a therapeutic option, because positive end-expiratory pressure (PEEP) can prevent airway collapse.(5-7) Kandaswamy et al.(8) reported that, among patients with respiratory distress who failed weaning from mechanical ventilation or required reintubation in the ICU, the prevalence of TBM, identified on CT scans of the chest acquired only days before intubation, was 1.6%. However, to our knowledge, there have been no reports of TBM being diagnosed during invasive mechanical ventilation. Electrical impedance tomography (EIT) is a noninvasive, radiation-free monitoring tool that provides real-time imaging of ventilation at the bedside. Here, we report a case in which the combination of CT and EIT scans of the chest allowed us to make the diagnosis of TBM and to determine the best PEEP titration for preventing airway collapse in an intubated patient. A 66-year-old female was admitted to the emergency room complaining of breathlessness. She had a history of recurrent episodes of wheezing and dry cough, both of which partially improved after treatment with aminophylline and inhaled short-acting bronchodilators. Her past medical history included orotracheal intubation, for severe bronchospasm, five years prior. She reported no fever, sputum production, or other symptoms. She stated that she had not been exposed to any inhaled allergens, had no known allergies, and had no family history of asthma. She reported that she was not a tobacco user but had long been exposed to biomass smoke from cooking. On physical examination, she was in respiratory distress, presenting with accessory muscle use, her RR was 28 breaths/min, and her SpO2 was 96% while breathing room air. Examination of the lungs revealed prolonged expiration and diffuse wheezing. The results of the radiographic assessment and laboratory exams were unremarkable. Partial symptomatic relief was achieved after inhalation therapy with ipratropium bromide and fenoterol, together with intravenous hydrocortisone. She was discharged home but returned to the emergency room with bronchospasm minutes later. Although she was then treated with additional doses of inhaled bronchodilators, as well as intravenous magnesium sulfate, her dyspnea worsened. A few hours later, she became comatose, requiring orotracheal intubation and admission to the ICU. At ICU admission, the patient was deeply sedated with fentanyl and midazolam, was started on inhaled albuterol (400 μg/h), received

Background: Lung derecruitment is common during general anesthesia. Mechanical ventilation with physiological tidal volumes could magnify derecruitment, and produce lung dysfunction and inflammation. The authors used positron emission tomography to study the process of derecruitment in normal lungs ventilated for 16 h and the corresponding changes in regional lung perfusion and inflammation. Methods: Six anesthetized supine sheep were ventilated with VT = 8 ml/kg and positive end-expiratory pressure = 0. Transmission scans were performed at 2-h intervals to assess regional aeration. Emission scans were acquired at baseline and after 16 h for the following tracers: (1) 18F-fluorodeoxyglucose to evaluate lung inflammation and (2) 13NN to calculate regional perfusion and shunt fraction. Results: Gas fraction decreased from baseline to 16 h in dorsal (0.31 ± 0.13 to 0.14 ± 0.12, P < 0.01), but not in ventral regions (0.61 ± 0.03 to 0.63 ± 0.07, P = nonsignificant), with time constants of 1.5–44.6 h. Although the vertical distribution of relative perfusion did not change from baseline to 16 h, shunt increased in dorsal regions (0.34 ± 0.23 to 0.63 ± 0.35, P < 0.01). The average pulmonary net 18F-fluorodeoxyglucose uptake rate in six regions of interest along the ventral–dorsal direction increased from 3.4 ± 1.4 at baseline to 4.1 ± 1.5⋅10−3/min after 16 h (P < 0.01), and the corresponding average regions of interest 18F-fluorodeoxyglucose phosphorylation rate increased from 2.0 ± 0.2 to 2.5 ± 0.2⋅10−2/min (P < 0.01). Conclusions: When normal lungs are mechanically ventilated without positive end-expiratory pressure, loss of aeration occurs continuously for several hours and is preferentially localized to dorsal regions. Progressive lung derecruitment was associated with increased regional shunt, implying an insufficient hypoxic pulmonary vasoconstriction. The increased pulmonary net uptake and phosphorylation rates of 18F-fluorodeoxyglucose suggest an incipient inflammation in these initially normal lungs.

To review the new (Berlin) definition of the acute respiratory distress syndrome (ARDS) and to propose potential improvements.The Berlin definition resulted in the following modifications: a criterion of less than 7 days was used to define acute onset; the requirement of pulmonary artery wedge pressure was removed. Clinical judgment for characterizing hydrostatic pulmonary edema suffices, unless there is no apparent ARDS risk factor, in which case an objective evaluation is required; the category of acute lung injury was removed, and ARDS was divided into three categories of severity based on the P/F ratio - mild (from 201 to 300), moderate (from 101 to 200), and severe (≤100 mmHg). A positive end-expiratory pressure value of at least 5 cm H(2)O became required for the diagnosis of ARDS. In this review, we propose that both the use of P/F ratio after some stabilization (first 24 h) and the use of compliance stratified at 0.4 ml/cm H(2)O/kg ideal body weight might improve the stratification of patients.The Berlin definition brought improvement and simplification over the previous definitions. The use of data over the first 24 h to reclassify the severity of the disease and the use of compliance to stratify each oxygenation category might further improve the definition.

OBJECTIVES: The aim of this manuscript is to describe the first year of our experience using extracorporeal membrane oxygenation support. METHODS: Ten patients with severe refractory hypoxemia, two with associated severe cardiovascular failure, were supported using venous-venous extracorporeal membrane oxygenation (eight patients) or veno-arterial extracorporeal membrane oxygenation (two patients). RESULTS: The median age of the patients was 31 yr (range 14-71 yr). Their median simplified acute physiological score three (SAPS3) was 94 (range 84-118), and they had a median expected mortality of 95% (range 87-99%). Community-acquired pneumonia was the most common diagnosis (50%), followed by P. jiroveci pneumonia in two patients with AIDS (20%). Six patients were transferred from other ICUs during extracorporeal membrane oxygenation support, three of whom were transferred between ICUs within the hospital (30%), two by ambulance (20%) and one by helicopter (10%). Only one patient (10%) was anticoagulated with heparin throughout extracorporeal membrane oxygenation support. Eighty percent of patients required continuous venous-venous hemofiltration. Three patients (30%) developed persistent hypoxemia, which was corrected using higher positive end-expiratory pressure, higher inspired oxygen fractions, recruitment maneuvers, and nitric oxide. The median time on extracorporeal membrane oxygenation support was five (range 3-32) days. The median length of the hospital stay was 31 (range 3-97) days. Four patients (40%) survived to 60 days, and they were free from renal replacement therapy and oxygen support. CONCLUSIONS: The use of extracorporeal membrane oxygenation support in severely ill patients is possible in the presence of a structured team. Efforts must be made to recognize the necessity of extracorporeal respiratory support at an early stage and to prompt activation of the extracorporeal membrane oxygenation team.

We recently described how spontaneous effort during mechanical ventilation can cause "pendelluft," that is, displacement of gas from nondependent (more recruited) lung to dependent (less recruited) lung during early inspiration. Such transfer depends on the coexistence of more recruited (source) liquid-like lung regions together with less recruited (target) solid-like lung regions. Pendelluft may improve gas exchange, but because of tidal recruitment, it may also contribute to injury. We hypothesize that higher positive end-expiratory pressure levels decrease the propensity to pendelluft and that with lower positive end-expiratory pressure levels, pendelluft is associated with improved gas exchange but increased tidal recruitment.Crossover design.University animal research laboratory.Anesthetized landrace pigs.Surfactant depletion was achieved by saline lavage in anesthetized pigs, and ventilator-induced lung injury was produced by ventilation with high tidal volume and low positive end-expiratory pressure. Ventilation was continued in each of four conditions: positive end-expiratory pressure (low or optimized positive end-expiratory pressure after recruitment) and spontaneous breathing (present or absent). Tidal recruitment was assessed using dynamic CT and regional ventilation/perfusion using electric impedance tomography. Esophageal pressure was measured using an esophageal balloon manometer.Among the four conditions, spontaneous breathing at low positive end-expiratory pressure not only caused the largest degree of pendelluft, which was associated with improved ventilation/perfusion matching and oxygenation, but also generated the greatest tidal recruitment. At low positive end-expiratory pressure, paralysis worsened oxygenation but reduced tidal recruitment. Optimized positive end-expiratory pressure decreased the magnitude of spontaneous efforts (measured by esophageal pressure) despite using less sedation, from -5.6 ± 1.3 to -2.0 ± 0.7 cm H2O, while concomitantly reducing pendelluft and tidal recruitment. No pendelluft was observed in the absence of spontaneous effort.Spontaneous effort at low positive end-expiratory pressure improved oxygenation but promoted tidal recruitment associated with pendelluft. Optimized positive end-expiratory pressure (set after lung recruitment) may reverse the harmful effects of spontaneous breathing by reducing inspiratory effort, pendelluft, and tidal recruitment.

Background: Protective mechanical ventilation strategies using low tidal volume or high levels of positive end-expiratory pressure (PEEP) improve outcomes for patients who have had surgery. The role of the driving pressure, which is the difference between the plateau pressure and the level of positive end-expiratory pressure is not known. We investigated the association of tidal volume, the level of PEEP, and driving pressure during intraoperative ventilation with the development of postoperative pulmonary complications. Methods: We did a meta-analysis of individual patient data from randomised controlled trials of protective ventilation during general anesthaesia for surgery published up to July 30, 2015. The main outcome was development of postoperative pulmonary complications (postoperative lung injury, pulmonary infection, or barotrauma). Findings: We included data from 17 randomised controlled trials, including 2250 patients. Multivariate analysis suggested that driving pressure was associated with the development of postoperative pulmonary complications (odds ratio [OR] for one unit increase of driving pressure 1·16, 95% CI 1·13-1·19; p