The Association between Prehospital Vulnerability, ARDS Development, and Mortality among At-Risk Adults. Results from the LIPS-A Clinical Trial

Mechanical Power: Using Ideal Body Weight to Identify Injurious Mechanical Ventilation Thresholds

Identifying the mechanisms of ventilator/ventilation-induced lung injury requires an understanding of the pulmonary physiology involved in the mechanical properties of the lung along with the involvement of the inflammatory cascade. Accurately measuring parameters that represent physiologic lung stress and lung strain at the bedside can be clinically challenging. Although surrogates for lung stress and strain have been proposed, such as plateau pressure and driving pressure, these values only represent a static variable in the ventilator breath. It has been proposed that a single variable could be used as a unifying parameter to identify a threshold for the safe application of mechanical ventilation. The concept of "mechanical power" applies an energy load transfer designation to the ventilator settings and output of tidal volume, airway pressures, and flow. However, there is a potential disconnect between the use of "absolute" mechanical power and the variability of body weight throughout a mixed medical population. Using ideal body weight as an influential factor to express mechanical power can potentially allow for a more accurate depiction of energy applied to the lungs and a potentially reliable injurious mechanical ventilation threshold indicator.

Assessment of bidirectional relationships between frailty and acute respiratory distress syndrome: a bidirectional Mendelian Randomization study

BACKGROUND

While previous observational studies have suggested a link between frailty and acute respiratory distress syndrome (ARDS), the causality of this connection remains unclear. The objective of this study was to explore the potential bidirectional causal links between frailty and ARDS.

METHODS

A two-sample univariable Mendelian randomization (MR) was performed to assess the causal relationship between frailty, as defined by frailty index (FI, n = 175,226) and fried frailty score (FFS, n = 386,565), and ARDS. The genome-wide association study (GWAS) data of frailty was from the UK Biobank and the ARDS data was from the FinnGen Database. Univariable MR analyses were conducted using inverse-variance weighted (IVW), weighted median, MR-Egger regression, and robust adjusted profile score (MR. RAPS). We also performed multivariable Mendelian randomization (MVMR) analysis including smoking initiation, alcohol consumption, body mass index (BMI), and cognitive performance.

RESULTS

This bidirectional MR analysis demonstrated no causal effect of FI (OR = 0.96, 95% CI 0.14-6.88) and FFS (OR = 1.95, 95%CI 0.14-28.16) on increased susceptibility of ARDS. Also, no evidence was found for an effect of ARDS on the risk of frailty. The MVMR analysis indicated higher BMI and poorer cognitive performance were associated with increased risk of ARDS.

CONCLUSIONS

The outcomes of our analysis imply a probable absence of a direct causal relationship between frailty and susceptibility to ARDS. To reinforce and expand upon these preliminary findings, it is imperative to conduct larger-scale genome-wide association studies.

Factors associated with acute respiratory distress syndrome in brain-injured patients: A systematic review and meta-analysis

PURPOSE

Acute respiratory distress syndrome (ARDS) is common in patients with acute brain injury admitted to the ICU. We aimed to identify factors associated with ARDS in this population.

METHODS

We searched MEDLINE, Embase, Cochrane Central, Scopus, and Web of Science from inception to January 14, 2022. Three reviewers independently screened articles and selected English-language studies reporting risk factors for ARDS in brain-injured adult patients. Data were extracted on ARDS incidence, adjusted and unadjusted risk factors, and clinical outcomes. Risk of bias was reported using the Quality in Prognostic Studies tool. Certainty of evidence was assessed using GRADE.

RESULTS

We selected 23 studies involving 6,961,284 patients with acute brain injury. The pooled cumulative incidence of ARDS after brain injury was 17.0% (95%CI 10.7-25.8). In adjusted analysis, factors associated with ARDS included sepsis (odds ratio (OR) 4.38, 95%CI 2.37-8.10; high certainty), history of hypertension (OR 3.11, 95%CI 2.31-4.19; high certainty), pneumonia (OR 2.69, 95%CI 2.35-3.10; high certainty), acute kidney injury (OR 1.44, 95%CI 1.30-1.59; moderate certainty), admission hypoxemia (OR 1.67, 95%CI 1.29-2.17; moderate certainty), male sex (OR 1.30, 95%CI 1.06-1.58; moderate certainty), and chronic obstructive pulmonary disease (OR 1.27, 95%CI 1.13-1.44; moderate certainty). Development of ARDS was independently associated with increased odds of in-hospital mortality (OR 3.12, 95% CI 1.39-7.00).

CONCLUSIONS

Multiple risk factors are associated with ARDS in brain-injured patients. These findings could be used to develop prognostic models for ARDS or as prognostic enrichment strategies for patient enrolment in future clinical trials.

Elevated Plasma Levels of Matrix Metalloproteinase-3 and Tissue-Inhibitor of Matrix Metalloproteinases-1 Associate With Organ Dysfunction and Mortality in Sepsis

BACKGROUND

Matrix Metalloproteinases (MMP) respond to tissue damage during sepsis. Higher plasma concentrations of MMPs and the tissue-inhibitor of matrix metalloproteinases (TIMP) have been reported in sepsis compared with healthy controls. The objective of this study was to examine if plasma levels of MMP-3, MMP-9, and TIMP-1 associate with mortality and organ dysfunction during sepsis.

METHODS

We conducted a prospective cohort study of critically ill patients with sepsis adjudicated per Sepsis-3 criteria at a tertiary academic medical center. We measured plasma concentrations of MMP-3, MMP-9, and TIMP-1 on intensive care unit admission. We phenotyped the subjects for shock, acute respiratory distress syndrome (ARDS), acute kidney injury (AKI), and mortality at 30 days. We used logistic regression to test the associations between the MMPs and TIMP-1 with shock, ARDS, AKI, and mortality.

RESULTS

Higher plasma TIMP-1 levels were associated with shock (odds ratio [OR] 1.51 per log increase [95% CI 1.25, 1.83]), ARDS (OR 1.24 [95% CI 1.05, 1.46]), AKI (OR 1.18 [95% CI 1.01, 1.38]), and mortality (OR 1.20 [95% CI 1.05, 1.46]. Higher plasma MMP-3 concentrations were associated with shock (OR 1.40 [95% CI 1.12, 1.75]) and mortality (OR 1.24 [95% CI 1.03, 1.48]) whereas MMP-9 levels were not associated with outcomes. Higher plasma TIMP-1 to MMP-3 ratios were associated with shock (OR 1.41 [95% CI 1.15, 1.72], P = 0.02).

CONCLUSION

Elevated plasma concentrations of TIMP-1 associate with organ dysfunction and mortality in sepsis. Higher plasma levels of MMP-3 associate with shock and mortality. Plasma MMP and TIMP-1 may warrant further investigation as emerging sepsis theragnostic biomarkers.

The long-lasting effects of the acute respiratory distress syndrome

Introduction: Acute respiratory distress syndrome (ARDS) is a severe form of acute lung injury common in critically ill patients and characterized by significant morbidity and mortality. It frequently manifests long-lasting effects beyond hospitalization, from cognitive impairment to physical weakness.Areas covered: Several complications of ARDS have been identified in patients after hospital discharge. The authors conducted literature searches to identify observational studies, randomized clinical trials, systematic reviews, and guidelines. A summary of is presented here to outline the sequelae of ARDS and their risk factors with a focus on the limited but growing research into possible therapies. Long term sequelae of ARDS commonly identified in the literature include long-term cognitive impairment, psychological morbidities, neuromuscular weakness, pulmonary dysfunction, and ongoing healthcare utilization with reduced quality of life.Expert opinion: Given the public health significance of long-term complications following ARDS, the development of new therapies for prevention and treatment is of vital importance. Furthering knowledge of the pathophysiology of these impairments will provide a framework to develop new therapeutic targets to fuel future clinical trials in this area of critical care medicine.