Explore the vast range of titles available.

Background In ARDS, the PEEP level associated with the best respiratory system compliance is often selected; however, intra-tidal recruitment can increase compliance, falsely suggesting improvement in baseline mechanics. Tidal lung hysteresis increases with intra-tidal recruitment and can help interpreting changes in compliance. This study aims to assess tidal recruitment in ARDS patients and to test a combined approach, based on tidal hysteresis and compliance, to interpret decremental PEEP trials. Methods A decremental PEEP trial was performed in 38 COVID-19 moderate to severe ARDS patients . At each step, we performed a low-flow inflation-deflation manoeuvre between PEEP and a constant plateau pressure, to measure tidal hysteresis and compliance. Results According to changes of tidal hysteresis, three typical patterns were observed: 10 (26%) patients showed consistently high tidal-recruitment, 12 (32%) consistently low tidal-recruitment and 16 (42%) displayed a biphasic pattern moving from low to high tidal-recruitment below a certain PEEP. Compliance increased after 82% of PEEP step decreases and this was associated to a large increase of tidal hysteresis in 44% of cases. Agreement between best compliance and combined approaches was accordingly poor (K = 0.024). The combined approach suggested to increase PEEP in high tidal-recruiters, mainly to keep PEEP constant in biphasic pattern and to decrease PEEP in low tidal-recruiters. PEEP based on the combined approach was associated with lower tidal hysteresis (92.7 ± 20.9 vs. 204.7 ± 110.0 mL; p  < 0.001) and lower dissipated energy per breath (0.1 ± 0.1 vs. 0.4 ± 0.2 J; p  < 0.001) compared to the best compliance approach. Tidal hysteresis ≥ 100 mL was highly predictive of tidal recruitment at next PEEP step reduction (AUC 0.97; p  < 0.001). Conclusions Assessment of tidal hysteresis improves the interpretation of decremental PEEP trials and may help limiting tidal recruitment and energy dissipated into the respiratory system during mechanical ventilation of ARDS patients.

Neuromuscular blocking agents (NMBAs) inhibit patient-initiated active breath and the risk of high tidal volumes and consequent high transpulmonary pressure swings, and minimize patient/ ventilator asynchrony in acute respiratory distress syndrome (ARDS). Minimization of volutrauma and ventilator-induced lung injury (VILI) results in a lower incidence of barotrauma, improved oxygenation and a decrease in circulating proinflammatory markers. Recent randomized clinical trials did not reveal harmful muscular effects during a short course of NMBAs. The use of NMBAs should be considered during the early phase of severe ARDS for patients to facilitate lung protective ventilation or prone positioning only after optimising mechanical ventilation and sedation. The use of NMBAs should be integrated in a global strategy including the reduction of tidal volume, the rational use of PEEP, prone positioning and the use of a ventilatory mode allowing spontaneous ventilation as soon as possible. Partial neuromuscular blockade should be evaluated in future trials.

This book examines ephemeral exhibitions from 1750 to 1918. In an era of acceleration and elusiveness, these transient spaces functioned as microcosms in which reality was shown, simulated, staged, imagined, experienced and known. They therefore had a dimension of spectacle to them, as the volume demonstrates. Against this backdrop, the different chapters deal with a plethora of spaces and spatial installations: the wunderkammer, the spectacle garden, cosmoramas and panoramas, the literary space, the temporary museum, and the alternative exhibition space.

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.

Purpose There is significant variability in the application of positive end-expiratory pressure (PEEP) in patients undergoing invasive mechanical ventilation. There are numerous studies assessing methods of determining optimal PEEP, but many methods, patient populations, and study settings lack high-quality evidence. Guidelines make no recommendations about the use of a specific method because of equipoise and lack of high-quality evidence. We conducted a scoping review to determine which methods of determining optimal PEEP have been studied and what gaps exist in the literature. Source We searched five databases for primary research reports studying methods of determining optimal PEEP among adults undergoing invasive mechanical ventilation. Data abstracted consisted of the titration method, setting, study design, population, and outcomes. Principle findings Two hundred and seventy-one studies with 17,205 patients met the inclusion criteria, including 73 randomized controlled trials (RCTs) with 10,733 patients. We identified 22 methods. Eleven were studied with an RCT. Studies enrolled participants within an intensive care unit (ICU) (216/271, 80%) or operating room (55/271, 20%). Most ICU studies enrolled patients with acute respiratory distress syndrome (162/216, 75%). The three most studied methods were compliance (73 studies, 29 RCTs), imaging-based methods (65 studies, 11 RCTs), and use of PEEP-F I O 2 tables (52 studies, 20 RCTs). Among ICU RCTs, the most common primary outcomes were mortality or oxygenation. Few RCTs assessed feasibility of different methods ( n  = 3). The strengths and limitations of each method are discussed. Conclusion Numerous methods of determining optimal PEEP have been evaluated; however, notable gaps remain in the evidence supporting their use. These include specific populations (normal lungs, patients weaning from mechanical ventilation) and using alternate outcomes (ventilator-free days and feasibility) and they present significant opportunities for future study. Study registration Open Science Framework ( https://osf.io/atzqc ); first posted, 19 July 2022.

Background Whether respiratory physiology of COVID-19-induced respiratory failure is different from acute respiratory distress syndrome (ARDS) of other etiologies is unclear. We conducted a single-center study to describe respiratory mechanics and response to positive end-expiratory pressure (PEEP) in COVID-19 ARDS and to compare COVID-19 patients to matched-control subjects with ARDS from other causes. Methods Thirty consecutive COVID-19 patients admitted to an intensive care unit in Rome, Italy, and fulfilling moderate-to-severe ARDS criteria were enrolled within 24 h from endotracheal intubation. Gas exchange, respiratory mechanics, and ventilatory ratio were measured at PEEP of 15 and 5 cmH 2 O. A single-breath derecruitment maneuver was performed to assess recruitability. After 1:1 matching based on PaO 2 /FiO 2 , FiO 2 , PEEP, and tidal volume, COVID-19 patients were compared to subjects affected by ARDS of other etiologies who underwent the same procedures in a previous study. Results Thirty COVID-19 patients were successfully matched with 30 ARDS from other etiologies. At low PEEP, median [25th–75th percentiles] PaO 2 /FiO 2 in the two groups was 119 mmHg [101–142] and 116 mmHg [87–154]. Average compliance (41 ml/cmH 2 O [32–52] vs. 36 ml/cmH 2 O [27–42], p  = 0.045) and ventilatory ratio (2.1 [1.7–2.3] vs. 1.6 [1.4–2.1], p  = 0.032) were slightly higher in COVID-19 patients. Inter-individual variability (ratio of standard deviation to mean) of compliance was 36% in COVID-19 patients and 31% in other ARDS. In COVID-19 patients, PaO 2 /FiO 2 was linearly correlated with respiratory system compliance ( r  = 0.52 p  = 0.003). High PEEP improved PaO 2 /FiO 2 in both cohorts, but more remarkably in COVID-19 patients ( p  = 0.005). Recruitability was not different between cohorts ( p  = 0.39) and was highly inter-individually variable (72% in COVID-19 patients and 64% in ARDS from other causes). In COVID-19 patients, recruitability was independent from oxygenation and respiratory mechanics changes due to PEEP. Conclusions Early after establishment of mechanical ventilation, COVID-19 patients follow ARDS physiology, with compliance reduction related to the degree of hypoxemia, and inter-individually variable respiratory mechanics and recruitability. Physiological differences between ARDS from COVID-19 and other causes appear small.

Older patients undergoing laparoscopic radical rectal cancer surgery under general anesthesia with mechanical ventilation face an increased risk of postoperative pulmonary atelectasis due to the Trendelenburg position and pneumoperitoneum. This study aims to assess whether lung ultrasound-guided individualized positive end-expiratory pressure(PEEP) ventilation can reduce postoperative atelectasis in older patients. Forty patients aged > 65 years scheduled for elective laparoscopic radical rectal cancer surgery were randomly assigned to two groups: the ultrasound-guided group (Group P) received individualized PEEP titrated by lung ultrasound, and the control group (Group C) maintained a fixed PEEP of 5 cmH 2 O. PEEP was maintained until extubation in both groups. Post-extubation, lung ultrasound assessed 12 regions in both lungs. Ultrasound-guided individualized PEEP values varied significantly between individuals [median (IQR): 11 (7-11.75) ]. Compared with the PEEP with a fixed 5 cmH 2 O, the incidence of postoperative pulmonary atelectasis (postoperative day 1: 0 vs. 25%; P  = 0.047) and severity [lung ultrasound score (LUS):8.5 (6-9.75) vs. 12.5 (10-13.75); P  < 0.001)] were lower in the patients undergoing the lung ultrasound PEEP titration strategy. Meanwhile, the intraoperative drive pressure(ΔP) (6.5 ± 2.8 vs. 10.4 ± 5.8; P  = 0.01) and the incidence of postoperative pulmonary complications(PPCs) (5% vs. 35%; P  = 0.044) were lower in the ultrasound-guided group, and intraoperative oxygenation index(OI) (461.5 ± 39.5 vs. 415.7 ± 69.1; P  = 0.014) and dynamic compliance(Cdyn) (36.4 ± 8.2 vs. 25.8 ± 8.9; P  < 0.001) were elevated. The perioperative hemodynamic characteristics were comparable between the two groups. Lung ultrasound-guided individualized PEEP decreased the incidence and severity of postoperative atelectasis in older patients undergoing laparoscopic rectal cancer surgery. This strategy improved intraoperative respiratory mechanics (Cdyn, ΔP, OI) and reduced PPCs without hemodynamic compromise. Trial registration This clinical trial was registered at the Chinese Clinical Trial Registry (Registration No.:ChiCTR2300078385, 07/12/2023, www.chictr.org.cn ).

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 PaO 2 /FiO 2 , higher arterial pH and lower PaCO 2 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.

Electrical Impedance Tomography (EIT) is a non-invasive imaging technique that uses changes in electrical conductivity to create images of the lungs. The utility of Electrical Impedance Tomography (EIT)-guided Positive End-Expiratory Pressure (PEEP) titration in improving outcomes in with Acute Respiratory Distress Syndrome (ARDS) patients in comparison to traditional PEEP titration methods. Extensive electronic database screening was done until 1st April 2023. Randomized Controlled Trials (RCT) evaluating the impact of the EIT-guided PEEP titration were included in this meta-analysis. Our search retrieved six RCTs with a total of 475 patients. No significant difference in P/F ratio [MD = −6.35;95%CI -19.32 to-6.6; I2 = 0%], driving pressure requirement [MD = −0.29;95%CI -0.84 to 0.25; I2 = 0%], PEEP optimization [MD = 0.05;95%CI -0.46 to 0.56; I2 = 87%], and successful weaning [OR = 1.35; 95% CI 0.8–2.2, I2 = 51%] with the application of EIT-guided PEEP titration. EIT-guided PEEP titration is a novel alternative, further well designed studies are needed for substantiating it's utility.