Prone positioning in severe acute respiratory distress syndrome

Influence of Prone Position on Regional Ventilation/Perfusion Matching in Patients With ARDS Over Time: A Prospective Physiological Study

Background: We sought to investigate the short- and long-term effects of prone positioning (PP) on ventilation/perfusion matching in patients with ARDS using contrast-enhanced electrical impedance tomography (EIT). Methods: EIT measurements were performed in 18 mechanically ventilated subjects with ARDS before PP (supine position [SP]), 1 h after turning subjects to PP (PP1), 3 h after PP (PP3), 9 h after (PP9), 16 h after PP (PP16; the end of PP), and 3 h after returning to the supine position (Re-SP3). Results: The P a O 2 /F I O 2 increased gradually during the PP period (110.68 vs 158.44 vs 210.15 vs 215.22 vs 236.04 vs 163.77 mm Hg, mean values at SP, PP1, PP3, PP9, PP16, and Re-SP3, respectively, P < .001). Global ventilation/perfusion matched percent significantly increased within PP duration (54.13% vs 63.15% vs 63.02% vs 63.75% vs 66.63% vs 57.42, P < .005). Compared with SP, dorsal ventilation significantly increased at PP1 (P < .001) and increased gradually during PP. However, the dorsal flow commenced to improve at PP9 and persisted in enhancement until PP16 (40.61% vs 48.78% vs 50.56%, mean values at PP3, PP9, and PP16, respectively, P < .05). There was a significant reduction in global Shunt-EIT percentage within PP duration, primarily localized in the dorsal area. Dead Space-EIT percentage remained unchanged during PP. Conclusions: Oxygenation remained improved or maintained throughout the 16-h duration of PP. Ventilation is susceptible to immediate gravitational effects; however, changes in blood flow may occur later after 9 h, which supports prolonged PP treatment. The shunt continuously decreases, but no significant changes were observed for dead space. Trial registration: ClinicalTrials.gov, NCT04725227. Registered on January 25, 2021.

Severe Acute Respiratory Distress Syndrome in an Adult Patient With Human Metapneumovirus Infection Successfully Managed With Veno-Venous Extracorporeal Membrane Oxygenation

Human metapneumovirus (hMPV), a ubiquitous RNA virus of the Pneumoviridae family, has been associated with respiratory tract infections for decades in various age groups and populations. Though most of the infections, especially in children, are mild and self-limited, severe infections ranging from bronchiolitis or asthma exacerbation to severe pneumonia and acute respiratory distress syndrome (ARDS) have occasionally been reported. Among patients who require hospitalization for severe infections, treatment is supportive as no current antivirals or vaccines are effective or recommended. The following is a 45-year-old Caucasian man who developed severe ARDS complicating hMPV infection, and despite maximal medical support, he developed refractory life-threatening hypoxemia that required rescue therapy with veno-venous extracorporeal membrane oxygenation (V-V ECMO). After several days of ECMO support, the patient eventually recovered and was discharged home. This case highlights the importance of recognizing hMPV as an occasional culprit for severe respiratory infections, discusses the new global definition of ARDS, and delineates the updated recommended management, including the early application of V-V ECMO as a rescue therapy in severe cases with refractory, life-threatening respiratory failure.

A descriptive, retrospective single-centre study of air-leak syndrome in intensive care unit patients with COVID-19

BACKGROUND

Acute respiratory failure is the predominant presentation of intensive care unit (ICU) patients with COVID-19, and lung protective strategies are recommended to mitigate additional respiratory complications such as air-leak syndrome. The aim of this study is to investigate the prevalence, type, and timing of air-leak syndrome with regards to associated factors and patient outcome in patients with COVID-19 in ICUs at a large Swedish emergency hospital.

METHODS

This retrospective study included all adult patients admitted to an ICU for COVID-19-related respiratory failure at Södersjukhuset between March 6, 2020, and June 6, 2021. Primary outcomes were proportion of patients diagnosed with air-leak syndrome and its different types of manifestations, and timing of diagnoses in relation to ICU admission and initiation of invasive ventilation. Secondary outcomes included the highest level of respiratory support prior to the diagnosis of air-leak syndrome, patient characteristics and treatment variables associated with air-leak syndrome, and 90-day mortality for patients with air-leak syndrome compared to those without.

RESULTS

Out of a total of 669 patients, 81 (12%) were diagnosed with air-leak syndrome. Air-leak syndrome manifested as pneumomediastinum (PMD) (n = 58, 72%), pneumothorax (PTX) (n = 43, 53%), subcutaneous emphysema (SCE) (n = 28, 35%) and pneumatocele (PC) (n = 4, 4.9%). Air-leak syndrome was diagnosed at a median of 14 days (IQR 6-22) after ICU admission and 12 days (IQR 6-19) following the initiation of invasive ventilation. The highest respiratory support prior to diagnosis was invasive ventilation (IV) in 64 patients (79%), non-invasive ventilation in two patients (2.5%), and low- or high-flow oxygen in 15 patients (19%). Multiple logistic regression showed that pulmonary disease at baseline (OR 1.87, 95% CI 1.07-3.25), a lower body mass index (OR 0.95, 95% CI 0.9-0.99), admission later compared with earlier in the pandemic (OR 3.89, 95% CI 2.14-7.08), and IV (OR 3.92, 95% CI 2.07-7.44) were associated with an increased risk of air-leak syndrome. Compared with patients not diagnosed with air-leak syndrome, patients with air-leaks had a higher mortality at 90 days after ICU admission, 46% versus 26% (p <.001). However, the mortality rate differed with different air-leak manifestations, 47% for PMD, 47% for PTX, 50% for the combination of both PMD and PTX and 0% in patients with only SCE and/or PC, respectively.

CONCLUSION

In 669 ICU patients with COVID-19, 12% had one or more manifestations of air-leak syndrome. Notably, PMD, rather than PTX, was the most common manifestation, suggesting a potentially distinctive feature of COVID-19-related air-leak syndrome. Further research is needed to determine whether COVID-19 involves different pathophysiological or iatrogenic mechanisms compared with other critical respiratory conditions.

REGISTRATION OF CLINICAL TRIAL

Clinicaltrials.gov, identifying number, NCT05877443.

EDITORIAL COMMENT

This single-centre cohort study of air leakage into soft tissue in ventilated COVID cases presents findings for associated factors and clinical manifestations, including with different COVID-19 periods and treatments.

Acute Lung Injury in Immunocompromised Patients

Acute lung injury is a devastating complication when occurring in immunocompromised patients. The incidence appears to be increasing as more patients survive for longer in this susceptible state. Being aware of potential causes of acute lung injury may lead to earlier recognition and diagnosis. Infection is a common cause of acute lung injury and needs to be considered in the diagnostic algorithm. Management involves use of supportive ventilatory strategies and potentially pharmacologic therapies.

Clinical and biological advances of critical complications in acute myeloid leukemia

Managing acute myeloid leukemia (AML) and its critical complications requires understanding the complex interplay between disease biology, treatment strategies, and patient characteristics. Complications like sepsis, acute respiratory failure (ARF), hyperleukocytosis, coagulopathy, tumor lysis syndrome (TLS) and central nervous system (CNS) involvement present unique challenges needing precise evaluation and tailored interventions. Venetoclax-induced TLS and differentiation syndrome (DS) from IDH1/IDH2 or menin inhibitors highlight the need for ongoing research and innovative approaches. As the microbiological landscape evolves and new therapeutic agents emerge, adapting strategies to mitigate harmful pharmacological interactions is crucial. Advances in understanding the genetic profiles of patients with hyperleukocytosis contribute to better-targeted therapeutic strategies. Effective AML management relies on collaborative efforts from hematologists, specialized services, and intensive care units (ICUs). This review analyzes recent data on critical AML complications, identifies areas for further investigation, and proposes ways to advance clinical research and enhance patient care strategies.

Effect of prone position on ventilation-perfusion matching in patients with moderate to severe ARDS with different clinical phenotypes

BACKGROUND

ARDS is a heterogeneous syndrome involving different subphenotypes with different clinical features and different responses to treatment strategies. The prone position (PP) is an effective treatment for ARDS; however, whether the effects of prone positioning vary among ARDS patients with different subphenotypes remains unknown.

OBJECTIVES

To evaluated the impact of PP on ventilation-perfusion matching(VQ matching) by contrast-enhanced Electrical impedance tomography (EIT) in ARDS patients with different subphenotypes.

METHODS

This was a prospective, observational study at the medical ICU of Zhongda Hospital, Southeast University. ARDS patients undergoing mechanical ventilation were screened and allocated to different subphenotypes based on lung morphology (focal/non-focal) and D-dimer level (low/high D-dimer). EIT was used in the supine position and 3 h, 6 h, and 12 h after the PP during the first PP session.

RESULTS

From July 1, 2021, to July 1, 2022, 25 patients were included in this study. 10 patients (40%) were focal ARDS, and 15 were non-focal ARDS based on baseline morphology. 12 patients (48%) were high D-dimer ARDS, and 13 were low D-dimer ARDS based on baseline D-dimer levels. PaO2/FiO2 increased significantly 3 h after prone positioning in focal ARDS patients (130.30[109.94-147.30] vs. 213.50[176.00-256.50] mmHg, p < 0.001), while the effect of improved oxygenation was not apparent until 6 h after prone positioning in non-focal ARDS patients (104.60[95.20-127.00] vs. 190.20[160.10-213.20] mm Hg, p < 0.001). VQ matching improved after 3 h in the prone position in the focal ARDS group (69.93 ± 6.69 vs. 78.22 ± 5.07, p = 0.006) but improved after only 6 h in the prone position in the non-focal ARDS group (67.32 ± 4.78 vs. 78.70 ± 5.93, p < 0.001). In ARDS patients with varying levels of D-dimer, increased PaO2/FiO2 (126.60[99.30-146.20] vs. 185.20[112.10-236.00] mmHg, p = 0.013) and improved VQ matching (67.60 ± 4.60 vs. 72.97 ± 6.48, p = 0.023) were observed at 3 h in the PP in patients with low D-dimer ARDS. In contrast, increased PaO2/FiO2(105.20[95.20-124.10] vs. 195.2[183.20-213.20], p < 0.001) and improved VQ matching (67.19 ± 6.70 vs. 72.50 ± 6.37, p < 0.001) were revealed only after 6 h in the prone position in high D-dimer ARDS patients.

CONCLUSIONS

For moderate to severe ARDS patients, non-focal and high D-dimer ARDS patients need longer PP to improve oxygenation and VQmatching than the focal and low D-dimer patients.

CLINICAL TRIAL REGISTRATION

This was a prospective, observational study registered in the Chinese Clinical Trial Registry (ChiCTR2200055442, https://www.chictr.org.cn/ ), on June 30, 2021.

Optimization of physiology in organ donors in the intensive care unit - what you need to know

ABSTRACT

Optimizing the physiology of organ donors is a critical component of preserving the option for organ donation and addressing the shortage of organs available for transplantation. In this article, we review common physiologic alterations seen in organ donors with a focus on brain-dead organ donors. These physiologic alterations and recommended interventions to optimize the physiology of the brain-dead organ donor are discussed by organ system, providing a framework for trauma surgeons and intensivists involved in the care of organ donors.

A narrative review on the future of ARDS: evolving definitions, pathophysiology, and tailored management

Acute respiratory distress syndrome (ARDS) is a severe complication of critical illness, characterized by bilateral lung infiltrates and hypoxemia. Its clinical and pathophysiological heterogeneity poses challenges for both diagnosis and treatment. This review outlines the evolution of ARDS definitions, discusses the underlying pathophysiology of ARDS, and examines the clinical implications of its heterogeneity. Traditional ARDS definitions required invasive mechanical ventilation and relied on arterial blood gas measurements to calculate the PaO2/FiO2 ratio. Recent updates have expanded these criteria to include patients receiving noninvasive respiratory support, such as high-flow nasal oxygen, and the adoption of the SpO2/FiO2 ratio as an alternative to the PaO2/FiO2 ratio. While these changes broaden the diagnostic criteria, they also introduce additional complexity. ARDS heterogeneity-driven by varying etiologies, clinical subphenotypes, and underlying biological mechanisms-highlights the limitations of a uniform management approach. Emerging evidence highlights the presence of distinct ARDS subphenotypes, each defined by unique molecular and clinical characteristics, offering a pathway to more precise therapeutic targeting. Advances in omics technologies-encompassing genomics, proteomics, and metabolomics-are paving the way for precision-medicine approaches with the potential to revolutionize ARDS management by tailoring interventions to individual patient profiles. This paradigm shift from broad diagnostic categories to precise, subphenotype-driven care holds promise for redefining the landscape of treatment for ARDS and, ultimately, improving outcomes in this complex, multifaceted syndrome.

Double the Trouble: Successful Cannulation and Air Transportation of Two Obese Trauma Patients Requiring Extracorporeal Membrane Oxygenation

Acute Respiratory Distress Syndrome (ARDS) is a known and severe complication of thoracic trauma. Many patients, despite appropriate ventilator and medical support, continue to worsen requiring additional cardiopulmonary support with extracorporeal membrane oxygenation (ECMO). Additionally, obesity adds a layer of complexity in the management of trauma ARDS on ECMO. We describe the first U.S. Military air transportation mission via Critical Care Air Transport (CCAT) involving the cannulation and transportation of 2 obese trauma patients requiring ECMO support. We reviewed a cohort of 2 obese patients with ARDS secondary to trauma cannulated for venovenous ECMO and simultaneously transferred via Critical Care Air Transport to a DoD ECMO Center. We describe the logistics involved in the transport and management of obese trauma patients on ECMO. Both patients were safely cannulated and transported without complications, and survived their ECMO run and hospital stay. This is the first air transport of 2 obese ECMO patients simultaneously in U.S. Military history. This transport highlights the safety of cannulation and transportation of obese trauma patients, in addition to the flexibility and logistics needed to successfully complete an ECMO military transport.

The effect of prone positioning on ventilator parameters, blood gas levels, and ventilator-associated pneumonia in intensive care unit patients: a randomized controlled trial

OBJECTIVES

This study was planned to compare the prone position and non-prone position groups and to evaluate arterial blood gas results, mechanical ventilator values and ventilator-associated pneumonia (VAP) status before, during, and after patients were brought back to the non-prone position.

DESIGN

This study is a randomized controlled trial with a parallel-group design and a 1:1 allocation ratio. A block randomisation method was used to ensure balanced allocation between two groups.

SETTING

The research was conducted in the 14-bed and 26-bed general ICUs of two private hospitals on the European side of Istanbul.

PARTICIPANTS

The 94 eligible participants were randomly divided into two groups. 52 participants were assigned to the prone position group, while 42 participants were assigned to the non-prone position group, which served as the control group. In the end, 40 participants were in each group.

INTERVENTION

The intervention involved placing patients in the prone position and monitoring their arterial blood gas results, mechanical ventilator values, and VAP status at multiple stages: before, during, and after returning them to the non-prone position. Each patient was followed for a minimum of 5 days.

RESULTS

The majority of the participants were male (51.2%) and aged 45-64 (48.8%). The comparison of experimental and control groups indicated statistically significant difference in saturation, FiO₂, inspiratory-expiratory tidal volume, and blood gas levels of the patients in the treatment group (p = 0.001; p < 0.01).

CONCLUSIONS

The change in the experimental group was greater than in the control group. In conclusion, the mechanical ventilator parameters and blood gas levels of the patients in the treatment group were better than those of the patients in the control group. It is recommended as an effective practice in patients receiving prone position mechanical ventilation (MV).

CLINICAL TRIAL REGISTRATION NUMBER AND REGISTRATION DATE

NCT05760716/ March 6, 2023 (This trial was registered retrospectively at ClinicalTrials.gov (Registration Number: NCT05760716) after its completion due to demanded revisions. The integrity of the data and adherence to the study protocol were ensured throughout. The trial adhered to ethical standards (ethics committee approval, informed consent) even if it was not registered prospectively).

Limitations of SpO2 / FiO2-ratio for classification and monitoring of acute respiratory distress syndrome-an observational cohort study

BACKGROUND

The ratio of pulse-oximetric peripheral oxygen saturation to fraction of inspired oxygen (SpO2/FiO2) has been proposed as additional hypoxemia criterion in a new global definition of acute respiratory distress syndrome (ARDS). This study aims to evaluate the clinical and theoretical limitations of the SpO2/FiO2-ratio when using it to classify patients with ARDS and to follow disease progression.

METHODS

Observational cohort study of ARDS patients from three high-resolution Intensive Care Unit databases, including our own database ICU Cockpit, MIMIC-IV (Version 3.0) and SICdb (Version 1.0.6). Patients with ARDS were identified based on the Berlin criteria or ICD 9/10-codes. Time-matched datapoints of SpO2, FiO2 and partial pressure of oxygen in arterial blood (PaO2) were created. Severity classification followed the thresholds for SpO2/FiO2 and PaO2/FiO2 of the newly proposed global definition.

RESULTS

Overall, 708 ARDS patients were included in the analysis. ARDS severity was misclassified by SpO2/FiO2 in 33% of datapoints, out of which 84% were classified as more severe. This can be partially explained by imprecision of SpO2 measurement and equation used to transform SpO2/FiO2 to PaO2/FiO2. A high dependence of SpO2/FiO2-ratio on FiO2 settings was found, leading to major treatment effect and limited capability for tracking change in ARDS severity, which was achieved in less than 20% of events.

CONCLUSIONS

The use of SpO2/FiO2 interchangeably with PaO2/FiO2 for severity classification and monitoring of ARDS is limited by its inadequate trending ability and high dependence on FiO2 settings, which may influence treatment decisions and patient selection in clinical trials.

Outcomes of Prone Positioning in Mechanically Ventilated COVID-19 Patients

Background: Prone positioning in mechanically ventilated patients with severe ARDS is associated with reduced mortality. COVID-19 causes variable pulmonary involvement in some patients suffering from severe respiratory failure and ARDS. Although proning in the COVID-19 patient population is increasingly common, more data are needed to fully understand its utility in those with ARDS due to COVID-19. Methods: We conducted a single-center retrospective study, inclusive of 100 consecutive subjects intubated for ARDS from COVID-19, admitted to the ICU from September 2020 to December 2020. Data were collected daily from time of intubation for 7 d along with 30-d outcomes. Results: The study included a total of 53 subjects proned and 47 nonproned during their hospitalization. Proned subjects had a mean age of 61.8 years and 56.6% were male, compared with a mean age of 66.3 years and 57.4% male in the nonproned group. Age, sex, other baseline characteristics, and treatments were similar between groups, except that proned subjects had a higher body mass index than nonproned subjects (34.1 ± 7.5 vs 30.5 ± 7.4, kg/m2 P = .02) and lower initial P/F ratios (119.1 ± 54.5 vs 154.0 ± 92.7 mm Hg, P = .047). Proned subjects received more neuromuscular blockade (OR 6.63, 95% CI 3.25-13.12, P < .001) and higher sedation levels (two sedatives: OR = 3.00, 95% CI 1.77-5.08; ≥3 sedatives: OR = 7.13, 95% CI 3.96-12.81) with similar ICU stays, ventilator days, newly initiated renal replacement therapy, and 30-d outcomes including being alive, out of the ICU, or discharged from the hospital when compared with nonproned subjects. There were a total of 15 (28.3%) complications related to proning. Proned subjects were reintubated significantly less than the nonproned group (1.9% vs 19.1%, P = .006). Conclusions: Proning mechanically ventilated COVID-19 subjects was associated with more frequent use of neuromuscular blockade and sedation, and lower rates of re-intubation, for respiratory failure when compared with nonproned subjects.

Pathophysiological mechanisms of ARDS: a narrative review from molecular to organ-level perspectives

BACKGROUND

Acute respiratory distress syndrome (ARDS) remains a life-threatening pulmonary condition with persistently high mortality rates despite significant advancements in supportive care. Its complex pathophysiology involves an intricate interplay of molecular and cellular processes, including cytokine storms, oxidative stress, programmed cell death, and disruption of the alveolar-capillary barrier. These mechanisms drive localized lung injury and contribute to systemic inflammatory response syndrome and multiple organ dysfunction syndrome. Unlike prior reviews that primarily focus on isolated mechanisms, this narrative review synthesizes the key pathophysiological processes of ARDS across molecular, cellular, tissue, and organ levels.

MAIN BODY

By integrating classical theories with recent research advancements, we provide a comprehensive analysis of how inflammatory mediators, metabolic reprogramming, oxidative stress, and immune dysregulation synergistically drive ARDS onset and progression. Furthermore, we critically evaluate current evidence-based therapeutic strategies, such as lung-protective ventilation and prone positioning, while exploring innovative therapies, including stem cell therapy, gene therapy, and immunotherapy. We emphasize the significance of ARDS subtypes and their inherent heterogeneity in guiding the development of personalized treatment strategies.

CONCLUSIONS

This narrative review provides fresh perspectives for future research, ultimately enhancing patient outcomes and optimizing management approaches in ARDS.

Electrical impedance tomography to set positive end-expiratory pressure

PURPOSE OF REVIEW

To summarize the rationale and concepts for positive end-expiratory pressure (PEEP) setting with electrical impedance tomography (EIT) and the effects of EIT-based PEEP setting on cardiopulmonary function.

RECENT FINDINGS

EIT allows patient-specific and regional assessment of PEEP effects on recruitability and overdistension, including its impact on ventilation-perfusion (V̇/Q) mismatch. The overdistension and collapse (OD-CL) method is the most used EIT-based approach for PEEP setting. In the RECRUIT study of 108 COVID-19 ARDS patients, the PEEP level corresponding to the OD-CL crossing point showed low overdistension and collapse (below 10% and 5%, respectively) regardless of recruitability. In a porcine model of acute respiratory distress syndrome (ARDS), it was shown that at this crossing point, respiratory mechanics (compliance, ΔP) were consistent, with adequate preload, lower right ventricular afterload, normal cardiac output, and sufficient gas exchange. A recent meta-analysis found that EIT based PEEP setting improved lung mechanics and potentially outcomes in ARDS patients. EIT thus provides critical insights beyond respiratory mechanics and oxygenation for individualized PEEP optimization. EIT-based methods for PEEP setting during assisted ventilation have also been proposed.

SUMMARY

EIT is a valuable technique to guide individualized PEEP setting utilizing cardiopulmonary information that is not captured by respiratory mechanics and oxygenation response alone.

The Protective Effects of Sivelestat Sodium on the Basis of Corticosteroid Therapy in Patients With Moderate-to-Severe Acute Respiratory Distress Syndrome

Objective: We aimed to evaluate the protective effects of sivelestat sodium on the basis of corticosteroid therapy in patients with moderate-to-severe acute respiratory distress syndrome (ARDS). Methods: We retrospectively investigated 127 patients with confirmed moderate-to-severe ARDS treated in the intensive care unit (ICU) at Dazhou Central Hospital. Patients were divided into the control group (corticosteroids alone) and the combination therapy of steroids and sivelestat sodium (CTSSS) group according to the therapeutic interventions. The primary outcome was in-hospital mortality. And the baseline characteristics and laboratory findings of patients were collected for analysis. Results: The overall mortality rate in 127 patients was 48.8%. There was no statistically significant difference in in-hospital mortality between the CTSSS group and the control group (45.3% vs. 56.1%). In the subgroup of patients aged < 80 years or with an Acute Physiology and Chronic Health Evaluation (APACHE) II score < 30, CTSSS could reduce the risk of mortality (odds ratio [OR] = 0.41, 95% confidence interval [CI], 0.17-0.96, p=0.041; OR = 0.31, 95% CI, 0.13-0.77, p=0.012; respectively). Among patients aged 80 years or older, those with CTSSS exhibited a significantly elevated risk of mortality (OR = 13; 95% CI, 1.20-140.73; p=0.035). Conclusion: Compared with corticosteroids alone, CTSSS could improve oxygenation index, increase lymphocyte count, protect extrapulmonary organs and reduce in-hospital mortality rate in patients with moderate-to-severe ARDS in specific subgroups (age < 80 years or APACHE II score < 30). It might be advisable to avoid CTSSS in moderate-to-severe ARDS patients aged 80 years or older. Prospective studies involving larger sample sizes are needed to verify these findings.

Effect of early and later prone positioning on outcomes in invasively ventilated COVID-19 patients with acute respiratory distress syndrome: analysis of the prospective COVID-19 critical care consortium cohort study

BACKGROUND

Prone positioning of patients with COVID-19 undergoing invasive mechanical ventilation (IMV) is widely used, but evidence of efficacy remains sparse. The COVID-19 Critical Care Consortium has generated one of the largest global datasets on the management and outcomes of critically ill COVID-19 patients. This prospective cohort study investigated the association between prone positioning and mortality and in particular focussed on timing of treatment.

METHODS

We investigated the incidence, demographic profile, management and outcomes of proned patients undergoing IMV for COVID-19 in the study. We compared outcomes between patients prone positioned within 48 h of IMV to those (i) never proned, and (ii) proned only after 48 h.

RESULTS

3131 patients had data on prone positioning, 1482 (47%) were never proned, 1034 (33%) were proned within 48 h and 615 (20%) were proned only after 48 h of commencement of IMV. 28-day (hazard ratio 0.82, 95% confidence interval [CI] 0.68, 0.98, p = 0.03) and 90-day (hazard ratio 0.81, 95% CI 0.68, 0.96, p = 0.02) mortality risks were lower in those patients proned within 48 h of IMV compared to those never proned. However, there was no evidence for a statistically significant association between prone positioning after 48 h with 28-day (hazard ratio 0.93, 95% CI 0.75, 1.14, p = 0.47) or 90-day mortality (hazard ratio 0.95, 95% CI 0.78, 1.16, p = 0.59).

CONCLUSIONS

Prone positioning is associated with improved outcomes in patients with COVID-19, but timing matters. We found no association between later proning and patient outcome.

Early Prone Positioning As a Rescue Therapy for Moderate-to-severe Primary Graft Dysfunction After Bilateral Lung Transplant

OBJECTIVES

Primary graft dysfunction (PGD) affects survival after lung transplant (LT). The current hypothesis was that prone positioning (PP), proposed as a rescue maneuver to treat refractory hypoxemia due to PGD, may improve LT outcomes, especially when applied early.

DESIGN

Bilateral LT recipients developing moderate-to-severe PGD within 24 hours from intensive care unit admission were enrolled. From January 2020 to November 2021, patients developing PGD after LT were turned prone between 24 and 48 hours after diagnosis, only in case of radiological or oxygenation worsening ("late PP" group). After November 2021, patients were routinely turned prone within 24 hours from PGD diagnosis ("early PP"). A propensity score-weighted analysis, adjusted for clinically relevant covariates, was applied.

SETTING

Intensive care unit.

PARTICIPANTS

Bilateral LT recipients.

INTERVENTIONS

Early PP, late PP, or supine position.

MEASUREMENTS AND MAIN RESULTS

130 LT patients were screened and 67 were enrolled. A total of 25 (37%) recipients were treated in the supine position, 24 (36%) in early PP, and 18 (27%) in late PP. After propensity score weighting, both supine treatment (estimated effect for 1 ventilator-free day = 8.23, standard error: 2.97, p = 0.007) and early PP treatment (estimated effect = 9.42, standard error: 2.59, p < 0.001) were associated with greater 28-day ventilator-free days than late PP treatment (reference). Compared with late PP, early PP was also associated with better oxygenation, driving pressure, and static respiratory system compliance. Compared with supine recipients, the early PP group showed better oxygenation at 72 hours after PGD diagnosis.

CONCLUSIONS

Early PP in LT recipients with moderate-to-severe PGD seems to be associated with better 28-day ventilator-free days, oxygenation, and driving pressure than late PP.

Ventilator-associated pneumonia risk factors in patients with severe COVID-19 in southern Brazil: A retrospective observational study

BACKGOUND

During the SARS-CoV-2 pandemic, a significant number of critical patients required ventilatory assistance in health institutions. In this context, Ventilator-Associated Pneumonia (VAP) was the most prevalent nosocomial infection among critically ill patients. We aimed to analyze the occurrence of VAP in critically ill patients with SARS-CoV-2 and the risk factors associated with the outcome.

METHOD

This is a multicenter, retrospective cohort study which included patients ≥18 years old, diagnosed with COVID-19, admitted to intensive care units (ICU) and who received invasive mechanical ventilation (MV) for >2 consecutive days. The associations between the variables were initially tested, and those that showed potential associations (p<0.05) were included in the multivariate logistic regression model.

RESULTS

One third of patients had an episode of VAP, with an incidence density of 34.97 cases per 1000 MV days. In addition, 42.37% (50) of the microorganisms causing VAP were multidrug-resistant, predominantly gram-negative bacteria (61.32%). More than 50% of participants developed healthcare-associated infections and 243 (73.64%) died. The factors associated with greater chances of VAP were: prone position (OR= 3.77), BMI 25-29.9 kg/m2 (OR= 4.76), pressure injury (OR= 4.41), length of stay in the ICU (OR= 1.06), positive tracheal aspirate before VAP (OR= 5.41) and dyspnea (OR= 3.80).

CONCLUSIONS

Patients with COVID-19 are at high risk of VAP, which leads to an increased risk of death (OR = 2.18). Multiple factors increase the chances of VAP in this population, namely: work overload in health institutions, prone position, prolonged ICU time, infusion of multiple drugs, invasive devices, and in particular, immobility in bed.

Prone Positioning in a Pregnant Woman With Severe Acute Respiratory Distress Syndrome: A Case Report

INTRODUCTION

Prone ventilation is a standard treatment for acute respiratory distress syndrome, and its clinical benefits are well established. However, implementing prone positioning safely and effectively is challenging in patients who are pregnant, have intra-abdominal hypertension, or are in other high-risk groups.

CLINICAL FINDINGS AND DIAGNOSIS

A patient in the third trimester of pregnancy (28 weeks and 6 days of gestation) developed a body temperature of 39 °C and severe respiratory distress. She was transferred to the intensive care unit, received noninvasive ventilation, and ultimately underwent endotracheal intubation. Because her oxygenation index remained below 100, she received a diagnosis of severe acute respiratory distress syndrome.

INTERVENTIONS

The patient was safely placed in the prone position with a swim ring while receiving venovenous extracorporeal membrane oxygenation. During this period, her intra-abdominal pressure did not increase significantly.

OUTCOMES

The fetus was delivered by cesarean birth, and the patient was transferred to the general ward after extubation.

CONCLUSION

This case report describes the use of prone positioning in a pregnant patient. The report offers critical care nurses insights into the clinical management of patients who are pregnant or have intra-abdominal hypertension.

Oxygenation improvement and duration of prone positioning are associated with ICU mortality in mechanically ventilated COVID-19 patients

BACKGROUND

Prone position has been diffusely applied in mechanically ventilated COVID-19 patients. Our aim is ascertaining the association between the physiologic response and the length of the first cycle of prone position and intensive care unit (ICU) mortality.

METHODS

International registry including COVID-19 adult patients who underwent prone positioning. We measured the difference for arterial partial pressure of oxygen to inspired fraction of oxygen ratio (PaO2/FiO2), ventilatory ratio, and respiratory system compliance (Crs) between baseline supine position and at either the end of the first cycle of prone position (Delta-PP) or re-supination (Delta-PostPP).

RESULTS

We enrolled 1816 patients from 53 centers. Delta-PP and Delta-PostPP for PaO2/FiO2 were both associated with ICU mortality [OR (95% CI) 0.48 (0.38, 0.59), and OR (95% CI) 0.60 (0.52, 0.68), respectively]. Ventilatory ratio had a non-linear relationship with ICU mortality for Delta-PP (p = 0.022) and Delta-PostPP (p = 0.004). Delta-PP, while not Delta-PostPP, for Crs was associated with ICU mortality [OR (95% CI) 0.80 (0.65, 0.98)]. The length of the first cycle of prone position showed an inverse relationship with ICU mortality [OR (95% CI) 0.82 (0.73, 0.91)]. At the multivariable analysis, the duration of the first cycle of prone position, Delta-PP and Delta-PostPP for PaO2/FiO2, and Delta-PostPP for ventilatory ratio were independently associated with ICU mortality.

CONCLUSION

In COVID-19 patients with acute respiratory failure receiving invasive mechanical ventilation and prone positioning, the physiological response to prone position is associated with ICU mortality. Prolonging the duration of the first cycle of prone position is associated with improved survival.

Is prone positioning a valid intervention for ARDS in the deployed intensive care unit?

Prone positioning is an intervention used for patients with acute respiratory distress syndrome (ARDS) whose hypoxia is worsening despite conventional treatment. Previously used infrequently, it became an important treatment escalation strategy for hypoxia during the COVID-19 pandemic. Current evidence for prone positioning suggests increased survivability in intubated patients with moderate to severe ARDS who are prone for >12 hours a day. As a relatively low-cost, low-tech intervention with a growing evidence base, the viability of prone positioning in the deployed land environment is considered in this article. The practical technique of prone positioning is easy to teach to healthcare staff experienced in manual handling. However, it requires significant resources, in particular staff numbers, and time to execute and maintain, and necessitates a pressure-minimising mattress. Additionally, staff are placed at increased risk of musculoskeletal injuries and potential exposure to aerosolised microbes if there is a disconnection of the breathing system. We conclude that in the deployed 2/1/2/12 facility (or larger), with access to higher staff numbers and high-specification mattresses, prone positioning is a valid escalation technique for intubated hypoxic patients with ARDS. However, in smaller facilities where resources are constrained, its implementation is unlikely to be achievable.

Lung injury in myocardial infarction-associated cardiogenic shock supported by venoarterial extracorporeal membrane oxygenation: a scoping review

BACKGROUND

Acute lung injury and acute respiratory failure are frequent complications of cardiogenic shock and are associated with increased morbidity and mortality. Even with increased use of temporary mechanical circulatory support, such as venoarterial extracorporeal membrane oxygenation (VA-ECMO), acute lung injury related to cardiogenic shock continues to have a determinantal effect on patient outcomes.

OBJECTIVES

To summarize potential mechanisms of acute lung injury described in patients with cardiogenic shock supported by VA-ECMO and determine current knowledge gaps.

METHODS

We searched literature from January 1st, 2010, to December 31st, 2023, using MEDLINE, EMBASE, and Web of Science databases on February 27th, 2024. The search strategy was split into two main domains: (a) cardiogenic shock and ECMO and (b) Acute respiratory failure and ECMO.

RESULTS

The search yielded 2246 citations. After 743 duplicates were removed, 1465 citations remained. Of these studies, 1456 were excluded based on the exclusion criteria, leaving the final eight studies we included in our scoping review. We identified disruption of the pulmonary blood flow in patients with cardiogenic shock, with cardiac arrest being an extreme form of cardiogenic shock. Placing the patient on VA-ECMO could intensify this process of lung injury.

CONCLUSION

Acute lung injury in patients with cardiogenic shock, especially when supported by VA ECMO, is a significant complication that is associated with increased morbidity and mortality. There is a limited understanding of the underlying mechanisms that could represent opportunities for future research to mitigate its development and provide the best approach to protecting and monitoring lung function.

Prone Positioning for Acute Respiratory Failure after PEA: An Initial Experience

BACKGROUND

 We retrospectively analyzed patients who underwent prone positioning (PP) for acute respiratory failure after pulmonary endarterectomy (PEA).

METHODS

 A total of 125 patients underwent PEA and the outcome related to patients who underwent PP for acute respiratory failure after surgery was analyzed.

RESULTS

 In all 13 patients (10%) underwent PP at the mean duration of 28.2 ± 10.6 hours after surgery and the mean prone time was 29.4 ± 9.8 hours. Compared with the pre-prone values, there was a significant improvement in the mean arterial oxygen to fraction of inspired oxygen ratio at the end of PP (119.4 ± 12.4 versus 202 ± 58.3) (p = 0.0002). Eight patients (61%) revealed a significant improvement in oxygenation with PP. Five patients who remained unresponsive underwent extracorporeal membrane oxygenation and four of them were weaned off successfully. In multivariate logistic stepwise analysis, the need for a moderate inotropy (odds ratio [OR]: 3.1) and low preoperative cardiac index (OR: 0.2) were independent predictors of PP. Under PP, the most common complication was ventilator-associated pneumonia (n = 9, 70%) and PP was found to be an independent predictor of ventilator-associated pneumonia (OR: 10.3). Early mortality was seen in three patients (23%, sepsis in two and adult respiratory distress syndrome in one).

CONCLUSION

 In the early care of acute respiratory failure following PTE, PP may be a feasible option, despite an increased risk of ventilator-associated pneumonia. More research involving a larger sample size is necessary.

Assessing the Impact of the Prone Position on Acute Kidney Injury

Background: Prone positioning is a standard intervention in managing patients with severe acute respiratory distress syndrome (ARDS) and is known to improve oxygenation. However, its effects on other organs, particularly the kidneys, are less well understood. This study aimed to assess the association between prone positioning and the development of acute kidney injury (AKI), specifically in overweight and obese patients. Methods: A retrospective pre-post study was conducted on a cohort of 60 critically ill ARDS patients who were placed in the prone position during hospitalization. The development of AKI was assessed using the Acute Kidney Injury Network (AKIN) criteria, with AKI measured by both creatinine levels (AKINCr) and urine output (AKINUO). Patients were divided into two groups based on body mass index (BMI): overweight/obese (BMI ≥ 25) and non-obese (BMI < 25). Data were collected before and after prone positioning. Results: In overweight/obese patients (n = 39, 57 cases), both the median AKINCr and AKINUO scores increased significantly following prone positioning (from 0 to 1, median p < 0.01, and from 0 to 2, median p < 0.01, respectively). No statistically significant changes in AKIN scores were observed in non-obese patients nor were significant differences found in either group after repositioning to supine. Conclusions: Prone positioning is associated with an increased risk of acute kidney injury in overweight and obese ARDS patients. This may be due to the kidneys' susceptibility to intra-abdominal hypertension in these patients. Further research is needed to explore optimal proning strategies for overweight and obese populations.

Establishment and validation of predictive model of ARDS in critically ill patients

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a prevalent complication among critically ill patients, constituting around 10% of intensive care unit (ICU) admissions and mortality rates ranging from 35 to 46%. Hence, early recognition and prediction of ARDS are crucial for the timely administration of targeted treatment. However, ARDS is frequently underdiagnosed or delayed, and its heterogeneity diminishes the clinical utility of ARDS biomarkers. This study aimed to observe the incidence of ARDS among high-risk patients and develop and validate an ARDS prediction model using machine learning (ML) techniques based on clinical parameters.

METHODS

This prospective cohort study in China was conducted on critically ill patients to derivate and validate the prediction model. The derivation cohort, consisting of 400 patients admitted to the ICU of the Peking University Third Hospital(PUTH) between December 2020 and August 2023, was separated for training and internal validation, and an external data set of 160 patients at the FU YANG People's Hospital from August 2022 to August 2023 was employed for external validation. Least absolute shrinkage and selection operator (LASSO) and multivariate logistic regression were used to screen predictor variables. Multiple ML classification models were integrated to analyze and identify the best models. Several evaluation indexes were used to compare the model performance, including the area under the receiver-operating-characteristic curve (AUC) and decision curve analysis (DCA). SHapley Additive ex Planations (SHAP) is used to interpret ML models.

RESULTS

400 critically ill patients were included in the analysis, with 117 developing ARDS during follow-up. The final model included gender, Lung Injury Prediction Score (LIPS), Hepatic Disease, Shock, and combined Lung Contusion. Based on the AUC and DCA in the validation group, the logistic model demonstrated excellent performance, achieving an AUC of 0.836 (95% CI: 0.762-0.910). For external validation, comprising 160 patients, 44 of whom developed ARDS, the AUC was 0.799 (95% CI: 0.723-0.875), significantly outperforming the LIPS score alone.

CONCLUSION

Combining the LIPS score with other clinical parameters in a logistic regression model provides a more accurate, clinically applicable, and user-friendly ARDS prediction tool than the LIPS score alone.

The Mechanical Power in Patients with Acute Respiratory Distress Syndrome Undergoing Prone Positioning Can Predict Mortality

Background/Objectives: Mechanical power (MP) refers to ventilator-delivered energy to the lungs, which may induce lung injury. We examined the relationship between MP and mortality in patients with acute respiratory distress syndrome (ARDS) who underwent prone positioning. Methods: This multicenter retrospective study included data on all patients admitted to the intensive care units of eight referral hospitals in Taiwan from October 2015 to March 2016, and in Chang Gung Memorial Hospital Linkou branch from January 2017 to October 2023. The data were obtained from the electronic medical records of each hospital by using a standard case report form. MP was calculated as follows: MP (J/min) = 0.098 × VT × RR × (Ppeak - 1/2 × ΔP). Results: We included 135 patients who underwent prone positioning. Among them, 28-day survivors had significantly lower MP (22.6 ± 6.5 vs. 25.3 ± 6.2 J/min, p = 0.024), MP/predicted body weight (PBW) (396.9 ± 118.9 vs. 449.3 ± 118.8 10-3 J/min/kg, p = 0.018), MP/compliance values (0.8 ± 0.3 vs. 1.1 ± 0.4 J/min/mL/cmH2O, p = 0.048) after prone positioning, and significantly lower changes in MP, MP/PBW, and MP/compliance (-0.6 ± 5.7 vs. 2.5 ± 7.4 J/min, p = 0.007; -9.2 ± 97.5 vs. 42.1 ± 127.9 10-3 J/min/kg, p = 0.010; -0.1 ± 0.3 vs. 0.2 ± 0.3 J/min/mL/cmH2O, p < 0.001, respectively). Multivariate Cox regression revealed that the change in MP/compliance (HR: 7.972, p < 0.001) was an independent predictive factor for 28-day mortality. Conclusions: In ARDS patients treated with prone positioning, MP/compliance, and change in MP, MP/PBW, and MP/compliance after prone positioning differed significantly between 28-day survivors and nonsurvivors. Further randomized controlled research is required to elucidate the potential causality of decreased MP and improved clinical outcomes.

Monitoring response to prone positioning

PURPOSE OF REVIEW

The increasing use of prone position, in intubated patients with acute respiratory distress syndrome as well as in patients with acute hypoxemic respiratory failure receiving noninvasive respiratory support, mandates a better definition and monitoring of the response to the manoeuvre. This review will first discuss the definition of the response to prone positioning, which is still largely based on its effect on oxygenation. We will then address monitoring respiratory and hemodynamic responses to prone positioning in intubated patients. Finally, we will also discuss monitoring inspiratory effort in nonintubated patients with acute hypoxemic respiratory failure who breathe spontaneously and receive noninvasive respiratory support.

RECENT FINDINGS

The response to prone positioning should be enriched by data pertaining to lung protection beyond oxygenation. These include trans-pulmonary pressure, driving pressure, mechanical power, distribution of aeration and ventilation and assessment of potential for lung recruitment before the pronation.

SUMMARY

The implications of present findings are to: better select those patients who will benefit from proning in physiological terms, better indicate the timing of onset and end of the sessions, and strengthen the relationship between physiological response and patient outcome.

Association between increasing institutional experience with ECPR and outcomes in patients with out-of-hospital cardiac arrest: A nationwide multicenter observational study in Japan (the JAAM-OHCA registry)

AIM

To determine the association between institutional experience with extracorporeal cardiopulmonary resuscitation (ECPR) and outcomes after out-of-hospital cardiac arrest (OHCA).

METHODS

We analyzed data from the JAAM-OHCA registry, a nationwide multicenter database containing information on patients who experienced OHCA in Japan between June 2014 and December 2020. The study population consisted of patients with OHCA who were in cardiac arrest on hospital arrival and treated with extracorporeal membrane oxygenation (ECMO). Each patient was assigned a sequential number based on the order of initiation of ECPR at each facility. The primary outcome was 30-day survival and the secondary outcome was the interval between hospital admission and initiation of ECMO.

RESULTS

Data for a total of 2,315 patients with OHCA and cardiac arrest on hospital arrival who were treated with ECPR at any of 87 facilities were analyzed. On admission, 1,047 patients had shockable rhythm and 1,268 had non-shockable rhythm. The 30-day survival rate was not significantly associated with the accumulated case volume of ECPR. The interval between hospital arrival and initiation of ECMO decreased significantly with increasing experience of ECPR (p < 0.001, Jonckheere-Terpstra test). In non-shockable cases, 30-day survival tended to improve with increasing experience of ECPR (p = 0.04, Cochran-Armitage trend test).

CONCLUSION

Increasing institutional experience of ECPR did not significantly improve 30-day survival after OHCA but was associated with a shorter interval between hospital arrival and initiation of ECMO. In patients with non-shockable OHCA, increasing experience of ECPR improved 30-day survival. (246/250 words).

Awake prone positioning and ventilation distribution as assessed by electric impedance tomography in patients with non-COVID-19 acute hypoxemic respiratory failure: A prospective physiology study

Background

Awake prone positioning (APP) can reportedly reduce the need for intubation and help improve prognosis of patients with acute hypoxemic respiratory failure (AHRF) infected with COVID-19. However, its physiological mechanism remains unclear. In this study, we evaluated the effect of APP on lung ventilation in patients with moderate-to-severe AHRF to better understand the effects on ventilation distribution and to prevent intubation in non-intubated patients.

Methods

The prospective study was performed in the Department of Critical Care Medicine at Shanghai General Hospital, China, from January 2021 to November 2022. The study included patients with AHRF (partial pressure of oxygen [PaO2]/inspired oxygen concentration [FiO2] <200 mmHg or oxygen saturation [SpO2]/FiO2 <235) treated with high-flow nasal oxygen. Electrical impedance tomography (EIT) measurements including center of ventilation (COV), global inhomogeneity (GI) index, and regional ventilation delay (RVD) index were performed in the supine position (T0), 30 min after the start of APP (T1), and 30 min returning to supine position after the APP (T2). Clinical parameters like SpO2, respiratory rate (RR), FiO2, heart rate (HR), and ROX (the ratio of SpO2 as measured by pulse oximetry/FiO2 to RR) were also recorded simultaneously at T0, T1, and T2. To evaluate the effect of the time points on the variables, Mauchly's test was performed for sphericity and repeated measures analysis of variance was applied with Bonferroni's post hoc multiple comparisons.

Results

Ten patients were enrolled. The PaO2/FiO2 ratio was (111.4±33.4) mmHg at the time of recruitment. ROX showed a significant increase after initiation of APP {median (interquartile range [IQR]): T0: 7.5 (6.0-10.1) vs. T1: 7.6 (6.4-9.3) vs. T2: 8.3 (7.2-11.0), P=0.043}. RR (P=0.409), HR (P=0.417), and SpO2/FiO2 (P=0.262) did not change significantly during prone positioning (PP). The COV moved from the ventral area to the dorsal area (T0: 48.8%±6.2% vs. T1: 54.8%±6.8% vs. T2: 50.3%±6.1%, P=0.030) after APP. The GI decreased significantly after APP (T0: median=42.7 %, [IQR: 38.3%-47.5%] vs. T1: median=38.2%, [IQR: 34.6%-50.7%] vs. T2: median=37.4%, [IQR: 34.2%-41.4%], P=0.049). RVD (P=0.794) did not change after APP.

Conclusions

APP can improve ventilation distribution and homogeneity of lung ventilation as assessed by EIT in non-intubated patients with AHRF.Trail Registration Chinese Clinical Trial Registry Identifier: ChiCTR2000035895.

Optimizing Management of Acute Respiratory Distress Syndrome in Critically Ill Surgical Patients: A Systematic Review

INTRODUCTION

This systematic review aims to evaluate the optimal management of acute respiratory distress syndrome (ARDS) in critically ill surgical patients, specifically focusing on positioning, extracorporeal membrane oxygenation (ECMO) use, ventilation, fluid resuscitation, and pharmacological treatments.

METHODS

A systematic review was conducted utilizing four databases including PubMed, Google Scholar, EMBASE, and ProQuest. This study followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered with The International Prospective Register of Systematic Reviews. Studies published until May 20, 2024, that assessed the management of ARDS in critically ill surgical adult populations were included in our review. The primary outcome of interest was mortality, with secondary outcomes like intensive care unit (ICU) length of stay (LOS), ventilator days, and oxygenation also being considered.

RESULTS

A total of fifteen studies met inclusion criteria; four studies assessed positional interventions, four assessed treatments with ECMO, three assessed mechanical ventilation settings, and four assessed fluid resuscitation and medications. Prone position was found to decrease mortality, ICU LOS, ventilator days, and increased oxygenation (P < 0.001). ECMO utilization decreased the overall mortality rate when compared to patients without ECMO (36.4% versus 43.9%, P < 0.001). Maintaining a tidal volume ≤8 mL/kg body weight and plateau pressure ≤35 cm H2O on mechanical ventilation also decreased patient mortality (P < 0.001). Finally, conservative fluid management decreased ICU LOS, whereas methylprednisolone use demonstrated decreased mortality.

CONCLUSIONS

Prone positioning, ECMO utilization, lung protective ventilation settings, and methylprednisolone reduced mortality among surgical patients with ARDS. In addition, prone positioning and conservative fluid management were associated with decreased ICU LOS, ventilator days, and improved oxygenation status.

ARDS Ventilation, The Man Behind the Evolution

How to cite this article: Prayag S. ARDS Ventilation, The Man Behind the Evolution. Indian J Crit Care Med 2025;29(1):12-13.

Extracorporeal membrane oxygenation in trauma patient in France: A retrospective nationwide registry

BACKGROUND

Indications for Veno-venous (VV) or veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) after trauma rely on poor evidence. The main aims were to describe the population of trauma patients requiring either VV or VA ECMO and report their clinical management and outcomes.

METHODS

An observational multicentre retrospective study was conducted in 17 Level 1 trauma centres in France between January 2010 and December 2021. All patients admitted for major trauma were screened for inclusion, and those receiving either VV ECMO or VA ECMO were included. The primary outcome was in-hospital mortality.

RESULTS

Among the 52,851 patients screened, 179 were included, with 143 supported by VV ECMO (median [Q1-Q3] age 32 years [24-48]; men 83.5%; injury severity score [ISS] 33 [25-43] and 76 (53.6%) with a traumatic brain injury [TBI]) and 36 supported by VA ECMO (median age 39 years [25-55]; men 88.9%; ISS 36 [25-56] and 23 (63.9%) with a TBI). In the VV ECMO group, three indications for ECMO implementation were chest injuries (n = 68, 47.6%), ventilator-associated pneumonia (VAP; n = 57, 39.9%), and extra-respiratory acute respiratory distress syndrome (ARDS; n = 57, 39.9%). In the VV ECMO group, 45.8% (n = 65) died in the hospital, with 33 (48.5%) deaths following cannulation for chest injuries, 22 (39.3%) following cannulation for VAP, and 10 (55.6%) following cannulation for extrapulmonary ARDS. In the VA ECMO group, 75.0% (n = 27) died during their hospital stay.

CONCLUSIONS

In-hospital mortality of trauma patients requiring ECMO for refractory ARDS varied according to indications. The best prognosis was observed in the subgroup of pneumonia-induced ARDS patients.

Ultrasound-Guided Venous Catheter Placement in Prone Position

The prone position is often used for patients with adult respiratory distress syndrome and specific surgical postures. When performing venous cannulation in this position, it is important to have a structured review to introduce the available major veins and ultrasound-guided procedure. In this review, we discuss the techniques of ultrasound-guided cannulation and provide insights into various aspects, including the anatomical locations of veins, vein sizes, placement techniques, surrounding structures at risk, and reported experiences with catheter placements. Eight major veins can be accessed in the prone position: the internal jugular vein, external jugular vein, brachiocephalic vein, basilic vein, mid-thigh femoral vein, popliteal vein, posterior tibial vein, and small saphenous vein. To minimize the risk of venous thromboembolism, the ratio of catheter diameter to vessel diameter should be less than 0.67. The review also presents the minimal requirement of venous diameter for different catheters in a tabulated form. For larger veins, real-time ultrasound guidance with the long-axis view/in-plane technique is suggested, while for smaller vessels, the short-axis view/out-of-plane technique is recommended. The review includes sonographic illustrations of the two techniques and surrounding arteries and nerves for the eight major veins. The aim of this review is to help clinicians assess the eight major veins and safely insert various types of catheters for patients in the prone position.

Elastic static power, its correlation with acute respiratory distress syndrome severity: A Bayesian post-hoc analysis of the Mechanical Power Day cross-sectional trial

OBJECTIVE

The relationship between different power equations and the severity of acute respiratory distress syndrome (ARDS) remains unclear. This study aimed to evaluate various power equations: total mechanical power, total elastic power (comprising elastic static and elastic dynamic power), and resistive power, in a cohort of mechanically ventilated patients with and without ARDS. Bayesian analysis was employed to refine estimates and quantify uncertainty by incorporating a priori distributions.

DESIGN

A Bayesian post-hoc analysis was conducted on data from the Mechanical Power Day study.

SETTING

113 intensive care units across 15 countries and 4 continents.

PATIENTS

Adults who received invasive mechanical ventilation in volume-controlled mode, with (mild and moderate/severe ARDS) and without ARDS.

INTERVENTIONS

None.

MAIN VARIABLES OF INTEREST

ARDS, Elastic static power.

RESULTS

Elastic static power was 5.8 J/min (BF: 0.3) in patients with mild ARDS and 7.4 J/min (BF: 0.9) in moderate/severe ARDS patients. Bayesian regression and modeling analysis revealed that elastic static power was independently correlated with mild (a posteriori Mean: 1.3; 95% Credible Interval [Cred. Interval]: 0.2-2.2) and moderate/severe ARDS (a posteriori Mean: 2.8; 95% Cred. Interval: 1.7-3.8) more strongly than other power equations.

CONCLUSIONS

Elastic static power was found to have the strongest correlation with ARDS severity among the power equations studied. Prospective studies are needed to further validate these findings.

Predictive value of trendelenburg position and carotid ultrasound for fluid responsiveness in patients on VV-ECMO with acute respiratory distress syndrome in the prone position

Fluid administration is widely used to treat hypotension in patients undergoing veno-venous extracorporeal membrane oxygenation (VV-ECMO). However, excessive fluid administration may lead to fluid overload can aggravate acute respiratory distress syndrome (ARDS) and increase patient mortality, predicting fluid responsiveness is of great significance for VV-ECMO patients. This prospective single-center study was conducted in a medical intensive care unit (ICU) and finally included 51 VV-ECMO patients with ARDS in the prone position (PP). Stroke volume index variation (ΔSVI), pulse pressure variation (PPV), stroke volume variation (SVV), baseline carotid corrected flow time (FTcBaseline), and respirophasic variation in carotid artery blood flow peak velocity (ΔVpeakCA) were taken before and after the Trendelenburg position or volume expansion. Fluid responsiveness was defined as a 15% or more increase in stroke volume index as assessed by transthoracic echocardiography after the volume expansion (VE). In our study, 33 patients (64.7%) were identified as fluid responders. Stroke volume index variation induced by the Trendelenburg position (ΔSVITrend), FTcBaseline, and ΔVpeakCA demonstrated superior predictive performance of fluid responsiveness. ΔSVITrend had an AUC of 0.89 (95% CI, 0.80-0.98) with an optimal threshold of 14.5% (95% CI, 12.5-21.5%), with the sensitivity and specificity were 82% (95% CI, 66-91%) and 83% (95% CI, 61-94%). FTcBaseline had an AUC of 0.87 (95% CI, 0.76-0.98) with an optimal threshold of 332ms (95% CI, 318-335ms), the sensitivity and specificity were 85% (95% CI, 69-93%) and 83% (95% CI, 61-94%), respectively. ΔVpeakCA showed an AUC of 0.83 (95% CI, 72-95), with a 10% optimal threshold (95% CI, 9-13%), sensitivity was 82% (95% CI, 66-91%) and specificity 78% (95% CI, 55-91%). ΔSVITrend, FTcBaseline and ΔVpeakCA could effectively predict fluid responsiveness in VV-ECMO patients with ARDS in the PP. Compared to ΔSVITrend and ΔVpeakCA, FTcBaseline is easier and more direct to acquire, and it does not require Trendelenburg position or VE, making it a more accessible and efficient option for assessing fluid responsiveness.

Effects of innovative modular prone positioning tools in patients with acute respiratory distress syndrome due to COVID-19 during awake prone position: a prospective randomized controlled trial

OBJECTIVES

Our aim is to investigate the effects of a innovative modular prone positioning tools on patients with acute respiratory distress syndrome (ARDS) caused by COVID-19 during awake prone positioning (AW-PP).

METHODS

This prospective randomized controlled study initially enrolled 168 patients with COVID-19 due to ARDS. However, 92 were subsequently disqualified, leaving 76 patients who were randomly assigned to either the observation group (n = 38) or the control group (n = 38). The observation group utilized innovative modular prone positioning tools for non-invasive respiratory support (NIRS), while the control group used soft pillows for the same treatment. Data were collected on comfort levels, adverse events, and efficacy indicators. Additionally, the comfort, incidence of adverse events, and treatment efficacy in both groups were evaluated.

RESULTS

The observation group had shorter the daily duration spent on executing the AW-PP (2.74 ± 0.86 min vs. 4.64 ± 1.02 min, P < 0.001), longer the daily total AW-PP (8.52 ± 1.01 h vs. 6.03 ± 0.66 h, P < 0.001), longer the daily duration until the first position adjustment (59.89 ± 12.73 min vs. 36.57 ± 8.69 min, P < 0.001), and lower the daily frequency of position adjustments during the AW-PP (11.03 ± 2.67 vs. 17.95 ± 2.58, P < 0.001) in comparison with the control group. No significant differences were observed in intubation rates, mortality, the daily number of hours under HFNO and NIV, escalated to NIV from HFNO, and hospital length of stay between the groups (P > 0.05). However, the observation group experienced significantly fewer adverse events, including kinking NIRS circuit, pain, shortness of breath, dizziness, and pressure ulcers (P < 0.05).

CONCLUSION

Innovative modular prone positioning tools improved efficiency, comfort, and reduced adverse events during AW-PP but did not affect intubation rates or mortality.

Body Positions and Physical Activity Levels Modulate the Ratio of Abdominal to Thoracic Breathing and Respiratory Rate in Young Individuals

Background/Objectives: The COVID-19 pandemic highlighted that body positions substantially affected the mortality rate. We hypothesized that body position modulates the contribution of abdominal (AB) and thoracic breathing (TB) to the breathing cycle (BC), as well as respiratory rate (RR). In addition, we hypothesized that physical activity level can increase the contribution of abdominal breathing. Methods: Thus, we used plethysmography respiratory belts to measure changes in abdominal (AB) and thoracic (TB) circumferences, their ratio (AB/TB), and respiratory rate (RR) under resting conditions. Measurements were taken in four body positions-standing (St), sitting (Si), supine (Su), and prone (Pr)-for two groups of young adults (aged 21 ± 2 years) with different physical activity levels (low and high PA). Results: The AB/TB ratios significantly differed between the body positions (Si: 45.5/54.5%, St: 40.5/59.5%, Su: 56.8/43.2%, Pr: 52.2/47.8% (p < 0.001)). AB was significantly the highest in Su and lowest in Si and St (p < 0.001). There was a significant difference in respiratory rate (RR) between the four body positions (p = 0.005). RR in the four body positions was the following: Si: 15.1, St: 15.0, Su: 13.7, and Pr: 14.4. RR was the lowest in Su (13.7), where AB was the highest (56.8%), and RR was the highest in Si (15.1) and St (15.0), where TB was higher compared to Su (p < 0.001). PA significantly affected the various body positions' AB/TB ratio and RR. The high PA group showed a significant difference in the AB/TB ratio between the body positions (p < 0.001). The low PA group showed a significant difference in RR between the body positions (p = 0.025). Conclusions: In young, healthy adults, we found that body position significantly influenced the abdominal/thoracic breathing ratio during the breathing cycle. The supine position showed the highest contribution of abdominal breathing, which correlated with the lowest respiratory rate. Additionally, a higher level of physical activity increased the contribution of abdominal breathing in the Si, Su, and St positions, suggesting a more energy-efficient breathing pattern. These findings suggest the potentials for breathing pattern monitoring and position-based interventions to improve healthcare outcomes and enhance sports performance and recovery.

Awake prone positioning effectiveness in moderate to severe COVID-19 a randomized controlled trial

Background

Awake prone positioning (APP) may be beneficial in patients with respiratory failure who are not receiving mechanical ventilation. Randomized controlled trials of APP have been performed during peak COVID-19 periods in unvaccinated populations, with limited data on compliance or patient acceptability. We aimed to evaluate the efficacy and acceptability of APP in a lower-middle income country in an open-label randomized controlled trial using a dedicated APP implementation team and wearable continuous-monitoring devices.

Methods

The trial was performed at a tertiary level hospital in Ho Chi Minh City, Vietnam, recruiting adults (≥18 years) hospitalized with moderate or severe COVID-19 and receiving supplemental oxygen therapy via nasal/facemask systems or high-flow nasal cannula (HFNC). Patients were allocated by a computer-generated random number sequence in a 1:1 ratio to standard care or APP, where a dedicated team provided bedside support. Wearable devices continuously recorded pulse oximetry and body position continuously. Our primary outcome was escalation of respiratory support within 28 days of randomization.

Results

Ninety-three patients were enrolled in this study between March 2022 and March 2023. Eighty (86%) patients had received ≥2 doses of SARS-CoV2 vaccine. The study was terminated early because of a reduction in the number of eligible patients. Data from 46 patients allocated to APP and 47 to standard care were available for analysis. At baseline, 19/47 (40%) patients allocated to the standard care group and 14/46 (30%) patients allocated to the APP group received HFNC. Continuous monitoring data were available for all patients monitored with wearable devices. Significantly greater mean daily APP times were achieved in those allocated to APP, however, most achieved less than the target 8 h/day. We did not detect clear differences in the primary outcome (relative risk,RR, 0.85, 95% CI 0.40-1.78, p=0.67) or secondary outcomes, including intubation rate and 28-day mortality. Patients reported prone positioning was comfortable, although almost all patients preferred supine positioning. No adverse events associated with the intervention were observed.

Conclusions

APP was not associated with benefit, but there was no sign of harm. Continuous monitoring with wearable devices is both feasible and acceptable for patients. In our population, achieving prolonged APP time was challenging despite a dedicated support team, and patients preferred supine positioning.

Clinical Trials Registration

NCT05083130.

Lysophosphatidylcholine 14:0 Alleviates Lipopolysaccharide-Induced Acute Lung Injury via Protecting Alveolar Epithelial Barrier by Activation of Nrf2/HO-1 Pathway

Background

Acute lung injury (ALI) is characterized by diffuse alveolar injury and acute non-cardiac pulmonary edema, with high morbidity and mortality. Lysophosphatidylcholine 14:0 (LPC14:0) has anti-inflammatory and anti-oxidative effects in sepsis and bacteremia. We hypothesized that LPC14:0 could be a potential treatment for ALI. Therefore, the effects of LPC14:0 on lung epithelial cells and the underlying mechanism on ALI were investigated.

Methods

Lipopolysaccharide (LPS) was instilled intratracheally in vivo while the Murine Lung Epithelial-12 was stimulated by tert-butyl hydroperoxide (t-BHP) in vitro to induce the ALI model. In vivo, lung injury was evaluated by histopathological changes and pulmonary edema was assessed by wet/dry ratio. Evans blue infiltration in lung tissue, total protein content, total cell counts and inflammatory factors in bronchoalveolar lavage fluid were evaluated for alveolar permeability. In vitro, cell viability and cell death rate were assessed by cell counting kit-8 and Calcein-AM/PI stain respectively. The expression of ZO-1, Occludin, Nrf2, and HO-1 was evaluated by Western blot.

Results

LPC14:0 attenuated the LPS-stimulated lung injury and oxidative stress in vivo, and alleviated the t-BHP-induced cell damage in vitro. Moreover, LPC14:0 significantly inhibited the degradation of the tight junction proteins and activated the Nrf2/HO-1 signaling pathway both in vivo and in vitro. Mechanistically, ML385, the Nrf2 inhibitor, inhibited the protective effects of LPC14:0 on barrier function in vitro.

Conclusion

This study first demonstrated that LPC14:0 mitigated LPS-induced ALI and the destruction of tight junctions, at least in part through up-regulation of the Nrf2/HO-1 pathway.

Physiologic effects of prone positioning on gas exchange and ventilation-perfusion matching in awake patients with AHRF

BACKGROUND

Prone positioning (PP) improves oxygenation in awake patients with acute hypoxemic respiratory failure (AHRF). However, the underlying mechanisms remain unclear in patients with diverse lung morphology. We aimed to determine the short-term effects of awake prone positioning (APP) in AHRF patients with focal and non-focal lung morphology.

METHODS

This is a prospective physiological study. Twenty-four non-intubated patients with PaO2/FiO2 ≤ 300 mm Hg were included. Gas exchange, ventilation and perfusion distribution, and hemodynamics variables were recorded in the supine position (SP1), 2 h after PP, and 1 h after re-supine (SP2). Lung morphology was classified as focal and non-focal patterns using computed tomography.

RESULTS

Twelve of the included patients were classified to the focal group and 12 to the non-focal group. PaO2/FiO2 improved after PP in all patients (161 [137, 227] mmHg vs. 236 [202, 275] mmHg, p < 0.001). Ventilation-perfusion (V/Q) matching increased after PP in all patients (61.9 [53.9, 66.5] vs. 77.5 [68.3, 80.0], p < 0.001). Shunt exhibited a significant decrease in patients of the non-focal group (28.6 [22.5, 30.3] vs. 11.3 [9.0, 14.5], p < 0.001), whereas no difference was found in the focal group after PP. Dead space decreased significantly in patients of the focal group (25.6 [21.5, 28.4] vs. 12.0 [10.8, 14.1], p < 0.001), whereas no difference was found in the non-focal group after PP.

CONCLUSIONS

APP improves V/Q matching, and large-scale, bias-free studies are needed to find more definitive differences between patients with focal and non-focal lung morphyology.

TRIAL REGISTRATION

The study is registered in ClinicalTrials.gov (trial No. NCT04754113, date of registration: 2021-02-15).

Early physiologic changes after awake prone positioning predict clinical outcomes in patients with acute hypoxemic respiratory failure

PURPOSE

The optimal physiologic parameters to monitor after a session of awake prone positioning in patients with acute respiratory failure are not well understood. This study aimed to identify which early physiologic changes after the first session of awake prone positioning are linked to the need for invasive mechanical ventilation or death in patients with acute respiratory failure.

METHODS

We performed a secondary analysis of a prospective cohort study of adult patients with acute respiratory failure related to coronavirus disease 2019 (COVID-19) treated with awake prone positioning. We assessed the association between relative changes in physiological variables (oxygenation, respiratory rate, pCO2 and respiratory rate-oxygenation [ROX] index) within the first 6 h of the first awake prone positioning session with treatment failure, defined as endotracheal intubation and/or death within 7 days.

RESULTS

244 patients [70 female (29%), mean age 60 (standard deviation [SD] 13) years] were included. Seventy-one (29%) patients experienced awake prone positioning failure. ROX index was the main physiologic predictor. Patients with treatment failure had lower mean [SD] ROX index at baseline [5 (1.4) versus 6.6 (2.2), p < 0.0001] and within 6 h of prone positioning [5.6 (1.7) versus 8.7 (2.8), p < 0.0001]. After adjusting for baseline characteristics and severity, a relative increase of the ROX index compared to baseline was associated with lower odds of failure [odds ratio (OR) 0.37; 95% confidence interval (CI) 0.25-0.54 every 25% increase].

CONCLUSION

Relative changes in the ROX index within 6 h of the first awake prone positioning session along with other known predictive factors are associated with intubation and mortality at day 7.

Oxygenation through oral Ox66 in a two-hit rodent model of respiratory distress

Acute respiratory distress syndrome (ARDS) is a complication of pulmonary disease that produces life-threatening hypoxaemia. Despite ventilation and hyperoxic therapies, undetected hypoxia can manifest in capillary beds leading to multi-organ failure. Ox66™ is an ingestible, solid-state form of oxygen designed to supplement oxygen deficits. Twenty-four anaesthetized rats underwent a two-hit model of respiratory distress (ARDS), where a single dose (5 mg/kg) of lipopolysaccharide (LPS) was given intratracheally, and then the respiratory tidal volume was reduced by 40%. After 60 min, animals were randomized to receive Ox66™, or normal saline (NS; vehicle control) via gavage or supplemental inspired oxygen (40% FiO2). A second gavage was administered at 120 min. Cardiovascular function and blood oximetry/chemistry were measured alongside the peripheral spinotrapezius muscle's interstitial oxygenation (PISFO2). ARDS reduced mean arterial pressure (MAP) and PISFO2 compared to baseline (BL) for all treatment groups. Treatment with Ox66 or NS did not improve MAP, but 40% FiO2 caused a rapid return to BL. PISFO2 improved after treatment with Ox66™ and 40% FiO2 and remained elevated for both groups against NS until study conclusion. Both oxygen treatments also suppressed the inflammatory response to LPS, suggesting that Ox66™ can deliver therapeutically-impactful levels of oxygen in situations of pulmonary dysfunction.

Definitions of Acute Respiratory Distress Syndrome: Present Recommendations and Challenges

Acute respiratory distress syndrome (ARDS) is an acute inflammatory process resulting in diffuse lung injury precipitated by an underlying risk factor. However, current definitions may pose barriers to the accurate diagnosis of this syndrome. These include changes in risk factors and associated disease evolution of ARDS, changes in contemporary clinical practice, and access to diagnostic tools required to diagnose ARDS in resource-limited settings. A consensus conference has proposed changes for an expanded global definition of ARDS. In this review article, we review challenges in defining ARDS and present recommendations of the global definition of ARDS.

Future Directions in Therapies for Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is caused by a complex interplay among hyperinflammation, endothelial dysfunction, and alveolar epithelial injury. Targeted treatments toward the underlying pathways have been unsuccessful in unselected patient populations. The first reliable biological subphenotypes reflective of these biological disease states have been identified in the past decade. Subphenotype targeted intervention studies are needed to advance the pharmacologic treatment of ARDS.

Acute respiratory distress syndrome: A review of ARDS across the life course

Acute respiratory distress syndrome (ARDS) is a multifactorial, inflammatory lung disease with significant morbidity and mortality that predominantly requires supportive care in its management. Although initially described in adult patients, the diagnostic definitions for ARDS have evolved over time to accurately describe this disease process in pediatric and, more recently, neonatal patients. The management of ARDS in each age demographic has converged in the application of lung-protective ventilatory strategies to mitigate the primary disease process and prevent its exacerbation by limiting ventilator-induced lung injury. However, differences arise in the preferred ventilatory strategies or adjunctive pulmonary therapies used to mitigate each type of ARDS. In this review, we compare and contrast the epidemiology, common etiologies, pathophysiology, diagnostic criteria, and outcomes of ARDS across the lifespan. Additionally, we discuss in detail the different management strategies used for each subtype of ARDS and spotlight how these strategies were applied to mitigate poor outcomes during the COVID-19 pandemic. This review is geared toward both clinicians and clinician-scientists as it not only summarizes the latest information on disease pathogenesis and patient management in ARDS across the lifespan but also highlights knowledge gaps for further investigative efforts. We conclude by projecting how future studies can fill these gaps in research and what improvements may be envisioned in the management of NARDS and PARDS based on the current breadth of literature on adult ARDS treatment strategies.