Acute respiratory distress syndrome (ARDS) is characterized by severe hypoxemia, low lung compliance, and marked regional heterogeneity of aeration, making the lung highly vulnerable to injurious mechanical forces. Mechanical ventilation is essential to maintain gas exchange. However, excessive stress and strain may contribute to ventilator-induced lung injury (VILI). The progressive transition to partial ventilatory support introduces an additional risk: patient self-inflicted lung injury (P-SILI), driven by vigorous inspiratory efforts, large transpulmonary pressure swings, pendelluft, and heterogeneous regional strain. Advances in monitoring, imaging, and physiology-based management offer the potential to reduce lung injury and improve outcomes in mechanically ventilated patients with ARDS. This review aims to summarize the clinical-physiological background of VILI and P-SILI, describe protective strategies during controlled and partially assisted ventilation, and discuss monitoring tools to personalize mechanical ventilation in ARDS.

Double cycling with breath-stacking (DC/BS) during controlled mechanical ventilation is considered potentially injurious, reflecting a high respiratory drive. During partial ventilatory support, its occurrence might be attributable to physiological variability of breathing patterns, reflecting the response of the mode without carrying specific risks. This secondary analysis of a crossover study evaluated DC/BS events in hypoxemic patients resuming spontaneous breathing in cross-over under neurally adjusted ventilatory assist (NAVA), proportional assist ventilation (PAV +), and pressure support ventilation (PSV). DC/BS was defined as two inspiratory cycles with incomplete exhalation. Measurements included electrical impedance signal, airway pressure, esophageal and gastric pressures, and flow. Breathing variability, dynamic compliance (CLdyn), and end-expiratory lung impedance (EELI) were analyzed. Twenty patients under assisted breathing, with a median of 9 [5–14] days on mechanical ventilation, were included. DC/BS was attributed to either a single (42

Pendelluft and expiratory muscle activity during spontaneous breathing should be minimized to reduce potential harmful effects. This study aimed to describe pendelluft and expiratory muscle activity in hypoxemic patients recovering spontaneous breathing after ≥ 72 h of lung-protective, fully controlled mechanical ventilation (MV) and assess the effect of pressure support ventilation (PSV) and positive end-expiratory pressure (PEEP). A physiological, randomized crossover study was conducted in hypoxemic patients receiving three levels of PSV: 5, 10, and 15 cmH₂O, and two PEEP levels: based on electrical impedance tomography before spontaneous breathing (PEEPEIT) or according to PEEP-FiO2 tables (PEEPARDS). Pendelluft was defined as the percentage of volume displaced from non-dependent to dependent lung regions during inspiration. Expiratory muscle activity was assessed by the expiratory rise in gastric pressure (ΔPgaEXP), and inspiratory effort was estimated using muscular pressure (Pmus). Statistical analyses included linear mixed-effects models and mediation analyses. Fifteen patients were enrolled (mean PaO2/FiO2 ratio: 262 ± 51 mmHg; median duration of MV: 9 [5–13] days; 6 females). PEEPEIT was 11 [10–13] cmH₂O and PEEPARDS 6 [5–7] cmH₂O. Expiratory muscle activity was observed in 13 patients. Compared to PS 5 cmH2O, PS to 10 and 15 cmH2O, adjusted for PEEP, significantly reduced both pendelluft and ΔPgaEXP (p < 0.001). When adjusted for PS, PEEPEIT was associated with a slight reduction in pendelluft (p = 0.039) but a concomitant increase in ΔPgaEXP (p = 0.007) compared to PEEPARDS. The mediation analysis revealed a significant negative mediating effect of ΔPgaEXP on the relationship between PEEPEIT and pendelluft (p < 0.001). Pmus, which was also significantly associated with pendelluft magnitude (p < 0.001), mediated the effect of PS on reducing pendelluft (p = 0.048), but not that of PEEP (p = 0.46). In patients with ARDS transitioning to spontaneous breathing, increasing PS reduces pendelluft and expiratory muscle activity. Higher PEEP can decrease pendelluft, but its effect can be counteracted by increased expiratory activity.

In the acute distress respiratory syndrome (ARDS), specific lung regions can be exposed to excessive strain due to heterogeneous disease, gravity-dependent lung collapse and injurious mechanical ventilation. Computed tomography (CT) is the gold standard for regional strain assessment. An alternative tool could be the electrical impedance tomography (EIT). We aimed to determine whether EIT-based methods can predict the dynamic relative regional strain (DRRS) between two levels of end-expiratory pressure (PEEP) in gravity-non-dependent and dependent lung regions. Fourteen ARDS patients underwent CT and EIT acquisitions (at end-inspiratory and end-expiratory) at two levels of PEEP: a low-PEEP based on ARDS-net strategy and a high-PEEP titrated according to EIT. Three EIT-based methods for DRRS were compared to relative CT-based strain: (1) the change of the ratio between EIT ventilation and end-expiratory lung impedance in arbitrary units ([ΔZAU low-PEEP/EELIAU low-PEEP]/[ΔZAU high-PEEP/EELIAU high-PEEP]), (2) the change of ΔZ/EELI ratio calibrated to mL ([ΔZml low-PEEP/EELIml low-PEEP]/[ΔZml high-PEEP/EELIml high-PEEP]) using CT data, and (3) the relative change of ∆ZAU (∆ZAU low-PEEP/∆ZAU high-PEEP). We performed linear regressions analysis and calculated bias and limits of agreement to assess the performance of DRRS by EIT in comparison with CT. The DRRS assessed by (ΔZml low-PEEP/EELIml low-PEEP)/(ΔZml high-PEEP/EELIml high-PEEP) and ∆ZAU low-PEEP/∆ZAU high-PEEP showed good relationship and agreement with the CT method (R2 of 0.9050 and 0.8679, respectively, in non-dependent region; R2 of 0.8373 and 0.6588, respectively, in dependent region; biases ranging from − 0.11 to 0.51 and limits of agreement ranging from − 0.73 to 1.16 for both methods and lung regions). Conversely, DRRS based on EELIAU ([ΔZAU low-PEEP/EELIAU low-PEEP]/[ΔZAU high-PEEP/EELIAU high-PEEP]) exhibited a weak negative relationship and poor agreement with the CT method for both non-dependent and dependent regions (R2 0.3; bias of 3.11 and 2.08, and limits of agreement of − 2.13 to 8.34 and from − 1.49 to 5.64, respectively). Changes in DRRS during a PEEP trial in ARDS patients could be monitored using EIT, based on changes in ΔZmL/EELIml and ∆ZAU. The relative change ∆ZAU offers the advantage of not requiring CT data for calibration.

BACKGROUND: Patient -ventilator asynchrony is common in patients undergoing mechanical ventilation. The proportion of health-care professionals capable of identifying and effectively managing different types of patient -ventilator asynchronies is limited. A few studies have developed specific training programs, but they mainly focused on improving patient -ventilator asynchrony detection without assessing the ability of health-care professionals to determine the possible causes. METHODS: We conducted a 36-h training program focused on patient -ventilator asynchrony detection and management for health-care professionals from 20 hospitals in Latin America and Spain. The training program included 6 h of a live online lesson during which 120 patient -ventilator asynchrony cases were presented. After the 6-h training lesson, health-care professionals were required to complete a 1-h training session per day for the subsequent 30 d. A 30 -question assessment tool was developed and used to assess health-care professionals before training, immediately after the 6-h training lecture, and after the 30 d of training (1 -month follow-up).RESULTS: One hundred sixteen health-care professionals participated in the study. The median (interquartile range) of the total number of correct answers in the pre -training, post -training, and 1 -month follow-up were significantly different (12 [8.75-15], 18 [13.75-22], and 18.5 [14-23], respectively). The percentages of correct answers also differed significantly between the time assessments. Study participants significantly improved their performance between pre -training and post -training (P < .001). This performance was maintained after a 1 -month follow-up (P 5 .95) for the questions related to the detection, determination of cause, and management of patient -ventilator asynchrony. CONCLUSIONS: A specific 36-h training program significantly improved the ability of health-care professionals to detect patient -ventilator asynchrony, determine the possible causes of patient -ventilator asynchrony, and properly manage different types of patient -ventilator asynchrony.

Background Internal redistribution of gas, referred to as pendelluft, is a new potential mechanism of effort-dependent lung injury. Neurally-adjusted ventilatory assist (NAVA) and proportional assist ventilation (PAV +) follow the patient’s respiratory effort and improve synchrony compared with pressure support ventilation (PSV). Whether these modes could prevent the development of pendelluft compared with PSV is unknown. We aimed to compare pendelluft magnitude during PAV + and NAVA versus PSV in patients with resolving acute respiratory distress syndrome (ARDS). Methods Patients received either NAVA, PAV + , or PSV in a crossover trial for 20-min using comparable assistance levels after controlled ventilation (> 72 h). We assessed pendelluft (the percentage of lost volume from the non-dependent lung region displaced to the dependent region during inspiration), drive (as the delta esophageal swing of the first 100 ms [ΔP es 100 ms ]) and inspiratory effort (as the esophageal pressure–time product per minute [PTP min ]). We performed repeated measures analysis with post-hoc tests and mixed-effects models. Results Twenty patients mechanically ventilated for 9 [5–14] days were monitored. Despite matching for a similar tidal volume, respiratory drive and inspiratory effort were slightly higher with NAVA and PAV + compared with PSV (ΔP es 100 ms of –2.8 [−3.8–−1.9] cm H 2 O, −3.6 [−3.9–−2.4] cm H 2 O and −2.1 [−2.5–−1.1] cm H 2 O, respectively, p < 0.001 for both comparisons; PTP min of 155 [118–209] cm H 2 O s/min, 197 [145–269] cm H 2 O s/min, and 134 [93–169] cm H 2 O s/min, respectively, p < 0.001 for both comparisons). Pendelluft magnitude was higher in NAVA (12 ± 7%) and PAV + (13 ± 7%) compared with PSV (8 ± 6%), p < 0.001. Pendelluft magnitude was strongly associated with respiratory drive (β = -2.771, p-value < 0.001) and inspiratory effort ( β = 0.026, p < 0.001), independent of the ventilatory mode. A higher magnitude of pendelluft in proportional modes compared with PSV existed after adjusting for PTP min ( β = 2.606, p = 0.010 for NAVA, and β = 3.360, p = 0.004 for PAV +), and only for PAV + when adjusted for respiratory drive (β = 2.643, p = 0.009 for PAV +). Conclusions Pendelluft magnitude is associated with respiratory drive and inspiratory effort. Proportional modes do not prevent its occurrence in resolving ARDS compared with PSV.

Prone positioning is an evidence-based treatment for patients with moderate-to-severe acute respiratory distress syndrome. Lung recruitment has been proposed as one of the mechanisms by which prone positioning reduces mortality in this group of patients. Recruitment-to-inflation ratio (R/I) is a method to measure potential for lung recruitment induced by a change in positive end-expiratory pressure (PEEP) on the ventilator. The association between R/I and potential for lung recruitment in supine and prone position has not been studied with computed tomography (CT) scan imaging. In this secondary analysis, we sought to investigate the correlation between R/I measured in supine and prone position with CT and the potential for lung recruitment as measured by CT scan. Among 23 patients, the median R/I did not significantly change from supine (1.9 IQR 1.6-2.6) to prone position (1.7 IQR 1.3-2.8) (paired t test p = 0.051) but the individual changes correlated with the different response to PEEP. In supine and in prone position, R/I significantly correlated with the proportion of lung tissue recruitment induced by the change of PEEP. Lung tissue recruitment induced by a change of PEEP from 5 to 15 cmH(2)O was 16% (IQR 11-24%) in supine and 14.3% (IQR 8.4-22.6%) in prone position, as measured by CT scan analysis (paired t test p = 0.56). In this analysis, PEEP-induced recruitability as measured by R/I correlated with PEEP-induced lung recruitment as measured by CT scan, and could help to readjust PEEP in prone position.

At the beginning of the COVID-19 pandemic in Chile, in March 2020, a projection indicated that a significant group of patients with pneumonia would require admission to an Intensive Care Unit and connection to a mechanical ventilator. Therefore, a paucity of these devices and other supplies was predicted. The initiative "Un respiro para Chile" brought together many people and institutions, public and private. In the course of three months, it allowed the design and building of several ventilatory assistance devices, which could be used in critically ill patients.

Editor—In dual-patient ventilation, the tidal volume (VT) delivered to patients depends on their respiratory mechanics, which can vary significantly between them.1–4 Thus, dual-patient ventilation might provide non-protective high VT to one patient, while supplying inadequate ventilation to the other because of low VT.5,6 To address this issue, splitters capable of regulating VT individually through implementation of valves and flow limiters have been devised. Dual-patient ventilation has been used in patients with similar respiratory mechanics, both without and with a splitter.

At the beginning of the COVID-19 pandemic in Chile, in March 2020, a projection indicated that a significant group of patients with pneumonia would require admission to an Intensive Care Unit and connection to a mechanical ventilator. Therefore, a paucity of these devices and other supplies was predicted. The initiative "Un respiro para Chile" brought together many people and institutions, public and private. In the course of three months, it allowed the design and building of several ventilatory assistance devices, which could be used in critically ill patients.

The transition from controlled to partial support ventilation is a challenge in acute respiratory distress syndrome (ARDS) patients due to the risks of patient-self-inflicted lung injury. The magnitude of tidal volume (V T ) and intrapulmonary dyssynchrony (pendelluft) are suggested mechanisms of lung injury. We conducted a prospective, observational, physiological study in a tertiary academic intensive care unit. ARDS patients transitioning from controlled to partial support ventilation were included. On these, we evaluated the association between changes in inflammatory biomarkers and esophageal pressure swing (ΔP es ), transpulmonary driving pressure (ΔP L ), V T , and pendelluft. Pendelluft was defined as the percentage of the tidal volume that moves from the non-dependent to the dependent lung region during inspiration, and its frequency at different thresholds (− 15, − 20 and − 25%) was also registered. Blood concentrations of inflammatory biomarkers (IL-6, IL-8, TNF-α, ANGPT2, RAGE, IL-18, Caspase-1) were measured before (T 0 ) and after 4-h (T 4 ) of partial support ventilation. Pendelluft, ΔP es , ΔP L and V T were recorded. Nine out of twenty-four patients (37.5%) showed a pendelluft mean ≥ 10%. The mean values of ΔP es , ΔP L , and V T were − 8.4 [− 6.7; − 10.2] cmH 2 O, 15.2 [12.3–16.5] cmH 2 O and 8.1 [7.3–8.9] m/kg PBW, respectively. Significant associations were observed between the frequency of high-magnitude pendelluft and IL-8, IL-18, and Caspase-1 changes (T 0 /T 4 ratio). These results suggest that the frequency of high magnitude pendelluft may be a potential determinant of inflammatory response related to inspiratory efforts in ARDS patients transitioning to partial support ventilation. Future studies are needed to confirm these results.

To describe the main factors associated with proper recognition and management of patient–ventilator asynchrony (PVA). An analytical cross-sectional study was carried out. An international study conducted in 20 countries through an online survey. Physicians, respiratory therapists, nurses and physiotherapists currently working in the Intensive Care Unit (ICU). Univariate and multivariate logistic regression models were used to establish associations between all variables (profession, training in mechanical ventilation, type of training program, years of experience and ICU characteristics) and the ability of HCPs to correctly identify and manage 6 PVA. A total of 431 healthcare professionals answered a validated survey. The main factors associated to proper recognition of PVA were: specific training program in mechanical ventilation (MV) (OR 2.27; 95%CI 1.14–4.52; p = 0.019), courses with more than 100 h completed (OR 2.28; 95%CI 1.29–4.03; p = 0.005), and the number of ICU beds (OR 1.037; 95%CI 1.01–1.06; p = 0.005). The main factor influencing the management of PVA was the correct recognition of 6 PVAs (OR 118.98; 95%CI 35.25–401.58; p < 0.001). Identifying and managing PVA using ventilator waveform analysis is influenced by many factors, including specific training programs in MV, the number of ICU beds, and the number of recognized PVAs. Describir los factores asociados al correcto reconocimiento y manejo de la asincronía paciente-ventilador (APV). Estudio analítico transversal. Estudio internacional realizado en 20 países mediante una encuesta a través de Internet. Médicos, terapeutas respiratorios, enfermeras/os y fisioterapeutas que trabajan actualmente en unidades de cuidados intensivos (UCI). Se utilizó un análisis uni y multivariado para describir la asociación entre todas las variables (profesión, formación en ventilación mecánica, tipo de programa de formación, años de experiencia y características de la UCI en la cual trabajan los profesionales) con la correcta identificación y manejo de 6 APV. Un total de 431 profesionales respondieron una encuesta validada previamente. Los factores asociados a una correcta identificación de 6 APV fueron: haber completado un programa de formación específico sobre ventilación mecánica (OR: 2,27; IC 95%: 1,14-4,52; p = 0,019), programa de formación con más de 100 h (OR: 2,28; IC 95%: 1,29-4,03; p = 0,005) y el número de camas de UCI (OR: 1,037; IC 95%: 1,01-1,06; p = 0,005). El principal factor asociado a un adecuado manejo de la APV fue la correcta identificación de 6 APV (OR: 118,98; IC 95%: 35,25-401,58; p < 0,001). La identificación y el manejo de la asincronía paciente-ventilador, mediante el análisis de las curvas del ventilador está influenciada por programas de formación, específicos sobre ventilación mecánica, el número de camas de la UCI y el número de asincronías identificadas correctamente.

RationaleCyclic strain may be a determinant of ventilator‐induced lung injury. The standard for strain assessment is the computed tomography (CT), which does not allow continuous monitoring and exposes to radiation. Electrical impedance tomography (EIT) is able to monitor changes in regional lung ventilation. In addition, there is a correlation between mechanical deformation of materials and detectable changes in its electrical impedance, making EIT a potential surrogate for cyclic lung strain measured by CT (StrainCT).ObjectivesTo compare the global StrainCT with the change in electrical impedance (ΔZ).MethodsAcute respiratory distress syndrome patients under mechanical ventilation (VT 6 mL/kg ideal body weight with positive end‐expiratory pressure 5 [PEEP 5] and best PEEP according to EIT) underwent whole‐lung CT at end‐inspiration and end‐expiration. Biomechanical analysis was used to construct 3D maps and determine StrainCT at different levels of PEEP. CT and EIT acquisitions were performed simultaneously. Multilevel analysis was employed to determine the causal association between StrainCT and ΔZ. Linear regression models were used to predict the change in lung StrainCT between different PEEP levels based on the change in ΔZ.Main resultsStrainCT was positively and independently associated with ΔZ at global level (P < .01). Furthermore, the change in StrainCT (between PEEP 5 and Best PEEP) was accurately predicted by the change in ΔZ (R2 0.855, P < .001 at global level) with a high agreement between predicted and measured StrainCT.ConclusionsThe change in electrical impedance may provide a noninvasive assessment of global cyclic strain, without radiation at bedside.

BACKGROUND: Auscultation is a fundamental part of the physical examination, but its utility has been questioned due to the low inter-rater concordance. We therefore sought to evaluate the concordance of the discrimination of lung sound recordings between experienced physiotherapists. METHODS: Lung sound recordings were selected and validated by an expert panel when Fleiss kappa concordance was > 0.75. Eleven recordings were played for subject recognition using a portable computer in their workplace. Results were analyzed using Fleiss kappa when looking for concordance between physiotherapists. Univariate regression was performed to determine if there was an association with clinical training, years of experience, academic accomplishment, or university affiliation. RESULTS: Sixty-nine physiotherapists with a median of 4 years of working experience (interquartile range 2-6 y) completed the study. There was moderate concordance (kappa = 0.562; 95% CI 0.462- 0.605) for overall lung sound recording discrimination. For continuous and noncontinuous lung sound recordings, discrimination concordance was substantial (kappa = 0.63 and kappa = 0.76, respectively). A bivariate analysis revealed that years of experience presented an inverse association with stridor recognition. CONCLUSIONS: Concordance between physiotherapists in discriminating recorded lung sounds was moderate. The ability to recognize stridor was inversely associated with years of work experience.

Due to the evidence of the oral consumption for tetrahidrocannabinol (THC) and/or cannabidiol (CBD) in patients with multiple sclerosis is still contradictory, a systematic review was performed to summarize its effects. The efficacy and safety of oral THC and/or CBD in patients with multiple sclerosis (MS) was assessed compared to standard treatment or placebo or no treatment in spasticity, through a systematic review (SR). Search algorithms were established for Cochrane Library, Pubmed, LILACS and Imbiomed. Meta-analysis (MA), randomized clinical trials (RCT) and cohort studies (CS) published until July 2019 were collected. The risk of bias was assessed by PRISMA, Cochrane GRADE and Consort methodology for MA, RCT and EC, respectively. A total of 296 studies were found, one MA, five RCTs and five CS met the inclusion criteria and demonstrated the use of THC and/or CBD in spasticity. The use of THC and/or CBD showed a significant decrease in spasticity in 9 out of 11 studies. These studies had a duration between 12 weeks and 1.5 years. The highest dose was 28 mg for both cannabinoids. One RCT assessed the efficacy of the cannabinoids in 538 patients who did not respond to their actual treatments. In general, the administration of cannabinoids improve the decrease of spasticity in ≥30%. Seven studies reported that patients who received cannabinoids struggle less to fall asleep than placebo arm. Cannabinoids were well tolerated and the main adverse events were dizziness and psychoactive effects. Short and long-term studies support the efficacy and safety profile of cannabinoids to decrease the frequency of spasticity in comparison to placebo.