Closed-loop oxygen control for critically ill patients--A systematic review and meta-analysis.

BACKGROUND: The impact of closed-loop control systems to titrate oxygen flow in critically ill patients, including their effectiveness, efficacy, workload and safety, remains unclear. This systematic review investigated the utilization of closed-loop oxygen systems for critically ill patients in comparison to manual oxygen titration systems focusing on these topics. METHODS AND FINDINGS: A search was conducted across several databases including MEDLINE, CENTRAL, EMBASE, LILACS, CINAHL, LOVE, ClinicalTrials.gov, and the World Health Organization on March 3, 2022, with subsequent updates made on June 27, 2023. Evidence databases were searched for randomized clinical parallel or crossover studies investigating closed-loop oxygen control systems for critically ill patients. This systematic review and meta-analysis was performed following the Preferred Reporting Items for Systematic Review and Meta-analysis guidelines. The analysis was conducted using Review Manager software, adopting the mean difference or standardized mean difference with a 95% confidence interval (95% CI) for continuous variables or risk ratio with 95% CI for dichotomous outcomes. The main outcome of interest was the percentage of time spent in the peripheral arterial oxygen saturation target. Secondary outcomes included time for supplemental oxygen weaning, length of stay, mortality, costs, adverse events, and workload of healthcare professional. A total of 37 records from 21 studies were included in this review with a total of 1,577 participants. Compared with manual oxygen titration, closed-loop oxygen control systems increased the percentage of time in the prescribed SpO2 target, mean difference (MD) 25.47; 95% CI 19.7, 30.0], with moderate certainty of evidence. Current evidence also shows that closed-loop oxygen control systems have the potential to reduce the percentage of time with hypoxemia (MD -0.98; 95% CI -1.68, -0.27) and healthcare workload (MD -4.94; 95% CI -7.28, -2.61) with low certainty of evidence. CONCLUSION: Closed-loop oxygen control systems increase the percentage of time in the preferred SpO2 targets and may reduce healthcare workload. TRIAL REGISTRATION: PROSPERO: CRD42022306033.

Intraoperative positive end-expiratory pressure and postoperative pulmonary complications: a patient-level meta-analysis of three randomised clinical trials.

BACKGROUND: High intraoperative PEEP with recruitment manoeuvres may improve perioperative outcomes. We re-examined this question by conducting a patient-level meta-analysis of three clinical trials in adult patients at increased risk for postoperative pulmonary complications who underwent non-cardiothoracic and non-neurological surgery. METHODS: The three trials enrolled patients at 128 hospitals in 24 countries from February 2011 to February 2018. All patients received volume-controlled ventilation with low tidal volume. Analyses were performed using one-stage, two-level, mixed modelling (site as a random effect; trial as a fixed effect). The primary outcome was a composite of postoperative pulmonary complications within the first week, analysed using mixed-effect logistic regression. Pre-specified subgroup analyses of nine patient characteristics and seven procedure and care-delivery characteristics were also performed. RESULTS: Complete datasets were available for 1913 participants ventilated with high PEEP and recruitment manoeuvres, compared with 1924 participants who received low PEEP. The primary outcome occurred in 562/1913 (29.4%) participants randomised to high PEEP, compared with 620/1924 (32.2%) participants randomised to low PEEP (unadjusted odds ratio [OR]=0.87; 95% confidence interval [95% CI], 0.75-1.01; P=0.06). Higher PEEP resulted in 87/1913 (4.5%) participants requiring interventions for desaturation, compared with 216/1924 (11.2%) participants randomised to low PEEP (OR=0.34; 95% CI, 0.26-0.45). Intraoperative hypotension was associated more frequently (784/1913 [41.0%]) with high PEEP, compared with low PEEP (579/1924 [30.1%]; OR=1.87; 95% CI, 1.60-2.17). CONCLUSIONS: High PEEP combined with recruitment manoeuvres during low tidal volume ventilation in patients undergoing major surgery did not reduce postoperative pulmonary complications. CLINICAL TRIAL REGISTRATION: NCT03937375 (Clinicaltrials.gov).

Effect of spontaneous breathing on ventilator-free days in critically ill patients-an analysis of patients in a large observational cohort.

BACKGROUND: Mechanical ventilation can injure lung tissue and respiratory muscles. The aim of the present study is to assess the effect of the amount of spontaneous breathing during mechanical ventilation on patient outcomes. METHODS: This is an analysis of the database of the 'Medical Information Mart for Intensive Care (MIMIC)'-III, considering intensive care units (ICUs) of the Beth Israel Deaconess Medical Center (BIDMC), Boston, MA. Adult patients who received invasive ventilation for at least 48 hours were included. Patients were categorized according to the amount of spontaneous breathing, i.e., ≥50% ('high spontaneous breathing') and <50% ('low spontaneous breathing') of time during first 48 hours of ventilation. The primary outcome was the number of ventilator-free days. RESULTS: In total, the analysis included 3,380 patients; 70.2% were classified as 'high spontaneous breathing', and 29.8% as 'low spontaneous breathing'. Patients in the 'high spontaneous breathing' group were older, had more comorbidities, and lower severity scores. In adjusted analysis, the amount of spontaneous breathing was not associated with the number of ventilator-free days [20.0 (0.0-24.2) vs. 19.0 (0.0-23.7) in high vs. low; absolute difference, 0.54 (95% CI, -0.10 to 1.19); P=0.101]. However, 'high spontaneous breathing' was associated with shorter duration of ventilation in survivors [6.5 (3.6 to 12.2) vs. 7.6 (4.1 to 13.9); absolute difference, -0.91 (95% CI, -1.80 to -0.02); P=0.046]. CONCLUSIONS: In patients surviving and receiving ventilation for at least 48 hours, the amount of spontaneous breathing during this period was not associated with an increased number of ventilator-free days.

Fluids in ARDS: more pros than cons.

In acute respiratory distress syndrome (ARDS), increased pulmonary vascular permeability makes the lung vulnerable to edema. The use of conservative as compared to liberal fluid strategies may increase the number of ventilator-free days and survival, as well as reduce organ dysfunction. Monitoring the effects of fluid administration is of the utmost importance; dynamic indexes, such as stroke volume and pulse pressure variations, outperform static ones, such as the central venous pressure. The passive leg raise and end-expiratory occlusion tests are recommended for guiding fluid management decisions. The type of intravenous fluids should also be taken into consideration: crystalloids, colloids, and human albumin have all been used for fluid resuscitation. Recent studies have also shown differences in outcome between balanced and non-balanced intravenous solutions. In preclinical studies, infusion of albumin promotes maintenance of the glycocalyx layer, reduces inflammation, and improves alveolar-capillary membrane permeability. Fluids in ARDS must be administered cautiously, considering hemodynamic and perfusion status, oncotic and hydrostatic pressures, ARDS severity, fluid type, volume and infusion rate, and cardiac and renal function. Of note, no guideline to date has recommended a specific fluid composition for use in ARDS; most physicians currently follow recommendations for sepsis.

Organizational factors associated with adherence to low tidal volume ventilation: a secondary analysis of the CHECKLIST-ICU database.

BACKGROUND: Survival benefit from low tidal volume (VT) ventilation (LTVV) has been demonstrated for patients with acute respiratory distress syndrome (ARDS), and patients not having ARDS could also benefit from this strategy. Organizational factors may play a role on adherence to LTVV. The present study aimed to identify organizational factors with an independent association with adherence to LTVV. METHODS: Secondary analysis of the database of a multicenter two-phase study (prospective cohort followed by a cluster-randomized trial) performed in 118 Brazilian intensive care units. Patients under mechanical ventilation at day 2 were included. LTVV was defined as a VT ≤ 8 ml/kg PBW on the second day of ventilation. Data on the type and number of beds of the hospital, teaching status, nursing, respiratory therapists and physician staffing, use of structured checklist, and presence of protocols were tested. A multivariable mixed-effect model was used to assess the association between organizational factors and adherence to LTVV. RESULTS: The study included 5719 patients; 3340 (58%) patients received LTVV. A greater number of hospital beds (absolute difference 7.43% [95% confidence interval 0.61-14.24%]; p = 0.038), use of structured checklist during multidisciplinary rounds (5.10% [0.55-9.81%]; p = 0.030), and presence of at least one nurse per 10 patients during all shifts (17.24% [0.85-33.60%]; p = 0.045) were the only three factors that had an independent association with adherence to LTVV. CONCLUSIONS: Number of hospital beds, use of a structured checklist during multidisciplinary rounds, and nurse staffing are organizational factors associated with adherence to LTVV. These findings shed light on organizational factors that may improve ventilation in critically ill patients.

Intraoperative immunomodulatory effects of sevoflurane versus total intravenous anesthesia with propofol in bariatric surgery (the OBESITA trial): study protocol for a randomized controlled pilot trial.

BACKGROUND: Obesity is associated with a chronic systemic inflammatory process. Volatile or intravenous anesthetic agents may modulate immune function, and may do so differentially in obesity. However, no study has evaluated whether these potential immunomodulatory effects differ according to type of anesthesia in obese patients undergoing laparoscopic bariatric surgery. METHODS/DESIGN: The OBESITA trial is a prospective, nonblinded, single-center, randomized, controlled clinical pilot trial. The trial will include 48 patients with a body mass index ≥ 35 kg/m2, scheduled for laparoscopic bariatric surgery using sleeve or a Roux-en-Y gastric bypass technique, who will be allocated 1:1 to undergo general inhalational anesthesia with sevoflurane or total intravenous anesthesia (TIVA) with propofol. The primary endpoint is the difference in plasma interleukin (IL)-6 levels when comparing the two anesthetic agents. Blood samples will be collected prior to anesthesia induction (baseline), immediately after anesthetic induction, and before endotracheal extubation. Levels of other proinflammatory and anti-inflammatory cytokines, neutrophil chemotaxis, macrophage differentiation, phagocytosis, and occurrence of intraoperative and postoperative complications will also be evaluated. DISCUSSION: To our knowledge, this is the first randomized clinical trial designed to compare the effects of two different anesthetics on immunomodulation in obese patients undergoing laparoscopic bariatric surgery. Our hypothesis is that anesthesia with sevoflurane will result in a weaker proinflammatory response compared to anesthesia with propofol, with lower circulating levels of IL-6 and other proinflammatory mediators, and increased macrophage differentiation into the M2 phenotype in adipose tissue. TRIAL REGISTRATION: Registro Brasileiro de Ensaios Clínicos, RBR-77kfj5 . Registered on 25 July 2018.

Effects of Protective Mechanical Ventilation With Different PEEP Levels on Alveolar Damage and Inflammation in a Model of Open Abdominal Surgery: A Randomized Study in Obese Versus Non-obese Rats.

Intraoperative positive end-expiratory pressure (PEEP) has been proposed to restore lung volumes and improve respiratory function in obesity. However, the biological impact of different PEEP levels on the lungs in obesity remains unknown. We aimed to compare the effects of PEEP = 2 cmH2O versus PEEP = 6 cmH2O during ventilation with low tidal volumes on lung function, histology, and biological markers in obese and non-obese rats undergoing open abdominal surgery. Forty-two Wistar rats (21 obese, 21 non-obese) were anesthetized and tracheotomized, and laparotomy was performed with standardized bowel manipulation. Rats were randomly ventilated with protective tidal volume (7 ml/kg) at PEEP = 2 cmH2O or PEEP = 6 cmH2O for 4 h, after which they were euthanized. Lung mechanics and histology, alveolar epithelial cell integrity, and biological markers associated with pulmonary inflammation, alveolar stretch, extracellular matrix, and epithelial and endothelial cell damage were analyzed. In obese rats, PEEP = 6 cmH2O compared with PEEP = 2 cmH2O was associated with less alveolar collapse (p = 0.02). E-cadherin expression was not different between the two PEEP groups. Gene expressions of interleukin (IL)-6 (p = 0.01) and type III procollagen (p = 0.004), as well as protein levels of tumor necrosis factor-alpha (p = 0.016), were lower at PEEP = 6 cmH2O than at PEEP = 2 cmH2O. In non-obese animals, PEEP = 6 cmH2O compared with PEEP = 2 cmH2O led to increased hyperinflation, reduced e-cadherin (p = 0.04), and increased gene expression of IL-6 (p = 0.004) and protein levels of tumor necrosis factor-alpha (p-0.029), but no changes in fibrogenesis. In conclusion, PEEP = 6 cmH2O reduced lung damage and inflammation in an experimental model of mechanical ventilation for open abdominal surgery, but only in obese animals.

Early versus delayed initiation of renal replacement therapy for acute kidney injury: an updated systematic review, meta-analysis, meta-regression and trial sequential analysis of randomized controlled trials. / Início precoce em comparação ao início tardio da terapia de substituição renal para lesão renal aguda: revisão sistemática atualizada, metanálise, metarregressão e análise sequencial de ensaios clínicos randomizados e controlados.

OBJECTIVE: To evaluate whether early initiation of renal replacement therapy is associated with lower mortality in patients with acute kidney injury compared to delayed initiation. METHODS: We performed a systematic review and meta-analysis of randomized controlled trials comparing early versus delayed initiation of renal replacement therapy in patients with acute kidney injury without the life-threatening acute kidney injury-related symptoms of fluid overload or metabolic disorders. Two investigators extracted the data from the selected studies. The Cochrane Risk of Bias Tool was used to assess the quality of the studies, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to test the overall quality of the evidence. RESULTS: Six randomized controlled trials (1,292 patients) were included. There was no statistically significant difference between early and delayed initiation of renal replacement therapy regarding the primary outcome (OR 0.82; 95%CI, 0.48 - 1.42; p = 0.488), but there was an increased risk of catheter-related bloodstream infection when renal replacement therapy was initiated early (OR 1.77; 95%CI, 1.01 - 3.11; p = 0.047). The quality of evidence generated by our meta-analysis for the primary outcome was considered low due to the risk of bias of the included studies and the heterogeneity among them. CONCLUSION: Early initiation of renal replacement therapy is not associated with improved survival. However, the quality of the current evidence is low, and the criteria used for -early- and -delayed- initiation of renal replacement therapy are too heterogeneous among studies.

OBJETIVO: Avaliar se, em comparação ao início tardio, o início precoce da terapia de substituição renal se associa com menor mortalidade em pacientes com lesão renal aguda. MÉTODOS: Conduzimos uma revisão sistemática e metanálise de ensaios clínicos randomizados e controlados, que compararam terapia de substituição renal com início precoce àquela com início tardio em pacientes com lesão renal aguda, sem sintomas relacionados à insuficiência renal aguda que oferecessem risco à vida, como sobrecarga hídrica ou distúrbios metabólicos. Dois investigadores extraíram os dados a partir de estudos selecionados. Utilizaram-se a ferramenta Cochrane Risk of Bias, para avaliar a qualidade dos estudos, e a abordagem Grading of Recommendations Assessment, Development and Evaluation (GRADE), para testar a qualidade geral da evidência. RESULTADOS: Incluíram-se seis estudos clínicos randomizados e controlados (1.292 pacientes). Não houve diferença estatisticamente significante entre o início precoce e tardio da terapia de substituição renal, no que se referiu ao desfecho primário (OR 0,82; IC95% 0,48 - 1,42; p = 0,488). Foi maior o risco de infecção da corrente sanguínea relacionada ao cateter quando a terapia de substituição renal foi iniciada precocemente (OR 1,77; IC95% 1,01 - 3,11; p = 0,047). A qualidade da evidência gerada por nossa metanálise para o desfecho primário foi considerada baixa, em razão do risco de viés dos estudos incluídos e da heterogeneidade entre eles. CONCLUSÃO: O início precoce da terapia de substituição renal não se associou com melhora da sobrevivência. Entretanto, a qualidade da evidência atual é baixa, e os critérios utilizados para início precoce e tardio da terapia de substituição renal foram demasiadamente heterogêneos entre os estudos.

Início precoce em comparação ao início tardio da terapia de substituição renal para lesão renal aguda: revisão sistemática atualizada, metanálise, metarregressão e análise sequencial de ensaios clínicos randomizados e controlados / Early versus delayed initiation of renal replacement therapy for acute kidney injury: an updated systematic review, meta-analysis, meta-regression and trial sequential analysis of randomized controlled trials

RESUMO Objetivo: Avaliar se, em comparação ao início tardio, o início precoce da terapia de substituição renal se associa com menor mortalidade em pacientes com lesão renal aguda. Métodos: Conduzimos uma revisão sistemática e metanálise de ensaios clínicos randomizados e controlados, que compararam terapia de substituição renal com início precoce àquela com início tardio em pacientes com lesão renal aguda, sem sintomas relacionados à insuficiência renal aguda que oferecessem risco à vida, como sobrecarga hídrica ou distúrbios metabólicos. Dois investigadores extraíram os dados a partir de estudos selecionados. Utilizaram-se a ferramenta Cochrane Risk of Bias, para avaliar a qualidade dos estudos, e a abordagem Grading of Recommendations Assessment, Development and Evaluation (GRADE), para testar a qualidade geral da evidência. Resultados: Incluíram-se seis estudos clínicos randomizados e controlados (1.292 pacientes). Não houve diferença estatisticamente significante entre o início precoce e tardio da terapia de substituição renal, no que se referiu ao desfecho primário (OR 0,82; IC95% 0,48 - 1,42; p = 0,488). Foi maior o risco de infecção da corrente sanguínea relacionada ao cateter quando a terapia de substituição renal foi iniciada precocemente (OR 1,77; IC95% 1,01 - 3,11; p = 0,047). A qualidade da evidência gerada por nossa metanálise para o desfecho primário foi considerada baixa, em razão do risco de viés dos estudos incluídos e da heterogeneidade entre eles. Conclusão: O início precoce da terapia de substituição renal não se associou com melhora da sobrevivência. Entretanto, a qualidade da evidência atual é baixa, e os critérios utilizados para início precoce e tardio da terapia de substituição renal foram demasiadamente heterogêneos entre os estudos.

ABSTRACT Objective: To evaluate whether early initiation of renal replacement therapy is associated with lower mortality in patients with acute kidney injury compared to delayed initiation. Methods: We performed a systematic review and meta-analysis of randomized controlled trials comparing early versus delayed initiation of renal replacement therapy in patients with acute kidney injury without the life-threatening acute kidney injury-related symptoms of fluid overload or metabolic disorders. Two investigators extracted the data from the selected studies. The Cochrane Risk of Bias Tool was used to assess the quality of the studies, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to test the overall quality of the evidence. Results: Six randomized controlled trials (1,292 patients) were included. There was no statistically significant difference between early and delayed initiation of renal replacement therapy regarding the primary outcome (OR 0.82; 95%CI, 0.48 - 1.42; p = 0.488), but there was an increased risk of catheter-related bloodstream infection when renal replacement therapy was initiated early (OR 1.77; 95%CI, 1.01 - 3.11; p = 0.047). The quality of evidence generated by our meta-analysis for the primary outcome was considered low due to the risk of bias of the included studies and the heterogeneity among them. Conclusion: Early initiation of renal replacement therapy is not associated with improved survival. However, the quality of the current evidence is low, and the criteria used for -early- and -delayed- initiation of renal replacement therapy are too heterogeneous among studies.

International multicenter observational study on assessment of ventilatory management during general anaesthesia for robotic surgery and its effects on postoperative pulmonary complication (AVATaR): study protocol and statistical analysis plan.

INTRODUCTION: Robotic-assisted surgery (RAS) has emerged as an alternative minimally invasive surgical option. Despite its growing applicability, the frequent need for pneumoperitoneum and Trendelenburg position could significantly affect respiratory mechanics during RAS. AVATaR is an international multicenter observational study aiming to assess the incidence of postoperative pulmonary complications (PPC), to characterise current practices of mechanical ventilation (MV) and to evaluate a possible association between ventilatory parameters and PPC in patients undergoing RAS. METHODS AND ANALYSIS: AVATaR is an observational study of surgical patients undergoing MV for general anaesthesia for RAS. The primary outcome is the incidence of PPC during the first five postoperative days. Secondary outcomes include practice of MV, effect of surgical positioning on MV, effect of MV on clinical outcome and intraoperative complications. ETHICS AND DISSEMINATION: This study was approved by the Institutional Review Board of the Hospital Israelita Albert Einstein. The study results will be published in peer-reviewed journals and disseminated at international conferences. TRIAL REGISTRATION NUMBER: NCT02989415; Pre-results.

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.

Associations between positive end-expiratory pressure and outcome of patients without ARDS at onset of ventilation: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: The aim of this investigation was to compare ventilation at different levels of positive end-expiratory pressure (PEEP) with regard to clinical important outcomes of intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) at onset of ventilation. METHODS: Meta-analysis of randomized controlled trials (RCTs) comparing a lower level of PEEP with a higher level of PEEP was performed. The primary outcome was in-hospital mortality. RESULTS: Twenty-one RCTs (1393 patients) were eligible. PEEP ranged from 0 to 10 cmH2O and from 5 to 30 cmH2O in the lower PEEP and the higher PEEP arms of included RCTs, respectively. In-hospital mortality was not different between the two PEEP arms in seven RCTs (risk ratio [RR] 0.87; 95% confidence interval [CI] 0.62-1.21; I 2 = 26%, low quality of evidence [QoE]), as was duration of mechanical ventilation in three RCTs (standardized mean difference [SMD] 0.68; 95% CI -0.24 to 1.61; I 2 = 82%, very low QoE). PaO2/FiO2 was higher in the higher PEEP arms in five RCTs (SMD 0.72; 95% CI 0.10-1.35; I 2 = 86%, very low QoE). Development of ARDS and the occurrence of hypoxemia (2 RCTs) were lower in the higher PEEP arms in four RCTs and two RCTs, respectively (RR 0.43; 95% CI 0.21-0.91; I 2 = 56%, low QoE; RR 0.42; 95%-CI 0.19-0.92; I 2 = 19%, low QoE). There was no association between the level of PEEP and any hemodynamic parameter (four RCTs). CONCLUSION: Ventilation with higher levels of PEEP in ICU patients without ARDS at onset of ventilation was not associated with lower in-hospital mortality or shorter duration of ventilation, but with a lower incidence of ARDS and hypoxemia, as well as higher PaO2/FiO2. These findings should be interpreted with caution, as heterogeneity was moderate to high, the QoE was low to very low, and the available studies prevented us from addressing the effects of moderate levels of PEEP.

Association between driving pressure and development of postoperative pulmonary complications in patients undergoing mechanical ventilation for general anaesthesia: a meta-analysis of individual patient data.

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<0·0001), whereas we detected no association for tidal volume (1·05, 0·98-1·13; p=0·179). PEEP did not have a large enough effect in univariate analysis to warrant inclusion in the multivariate analysis. In a mediator analysis, driving pressure was the only significant mediator of the effects of protective ventilation on development of pulmonary complications (p=0·027). In two studies that compared low with high PEEP during low tidal volume ventilation, an increase in the level of PEEP that resulted in an increase in driving pressure was associated with more postoperative pulmonary complications (OR 3·11, 95% CI 1·39-6·96; p=0·006). INTERPRETATION: In patients having surgery, intraoperative high driving pressure and changes in the level of PEEP that result in an increase of driving pressure are associated with more postoperative pulmonary complications. However, a randomised controlled trial comparing ventilation based on driving pressure with usual care is needed to confirm these findings. FUNDING: None.

Incidence and Mortality of Acute Respiratory Distress Syndrome in Children: A Systematic Review and Meta-Analysis.

OBJECTIVES: Our understanding of the acute respiratory distress syndrome in children is limited, and literature is dominated by investigations in adult patients. Recent preclinical studies suggest that the susceptibility to and severity of acute respiratory distress syndrome in children could differ from that in adults. We assessed the incidence and mortality of acute respiratory distress syndrome reported in children in studies published in the last two decades. DATA SOURCES: Medline, Embase, and CINAHL databases were searched up to August 2014. STUDY SELECTION: Articles reporting study data on population- or PICU-based incidence and mortality of acute respiratory distress syndrome in children (> 36 wk gestation and < 18 yr old) were selected. DATA EXTRACTION: Two authors independently collected data and assessed methodological quality and risk of bias of selected studies. Pooled estimates of incidence and mortality were calculated using random-effects models. To explore heterogeneity, influence of study characteristics, including median year of conduct, study location, inclusion and exclusion criteria, and study design and quality, was assessed by meta-regression analysis. DATA SYNTHESIS: Twenty-nine studies reported on incidence and 32 on mortality. Pooled weighted estimate of the population-based and PICU-based incidence of pediatric acute respiratory distress syndrome was 3.5 (95% CI, 2.2-5.7) cases per 100,000 person years and 2.3% (95% CI, 1.9-2.9), respectively. Pooled weighted mortality was 33.7% (95% CI, 28.6-39.7). There were no trends over time, but mortality was significantly associated with study location. CONCLUSIONS: This systematic review and meta-analysis shows a low incidence but a high mortality. Its results also indicate that both incidence and mortality of pediatric acute respiratory distress syndrome have not changed over the last two decades and that mortality depends on the geographic location of studies.