Do newer monitors of exhaled gases, mechanics, and esophageal pressure add value?

Acute Respiratory Distress Syndrome; A Review of Recent Updates and a Glance into the Future

Acute respiratory distress syndrome (ARDS) is a rapidly progressive form of respiratory failure that accounts for 10% of admissions to the ICU and is associated with approximately 40% mortality in severe cases. Despite significant mortality and healthcare burden, the mainstay of management remains supportive care. The recent pandemic of SARS-CoV-2 has re-ignited a worldwide interest in exploring the pathophysiology of ARDS, looking for innovative ideas to treat this disease. Recently, many trials have been published utilizing different pharmacotherapy targets; however, the long-term benefits of these agents remain unknown. Metabolomics profiling and stem cell transplantation offer strong enthusiasm and may completely change the outlook of ARDS management in the near future.

The relationship between oxidative stress markers in exhaled breath condensate and respiratory problems in patients with repaired esophageal atresia

AIM

To evaluate the relationship between respiratory problems and oxidative stress markers in exhaled breath condensate (EBC) of patients with esophageal atresia (EA).

METHODS

EA cases with respiratory problems were evaluated retrospectively for age, gender, the type of atresia, surgical treatment, outcome and respiratory symptoms. The results of gastroesophageal reflux (GER) treatment including the use of proton pump inhibitor (PPI) and fundoplication were also documented. EBC samples of 500-1000 μl were obtained by Ecoscreen machine in all cases. The levels of Glutathione (Glut), 8-isoprostane (8-iso), cysteinyl-leukotriene (Cys-LT) were measured with ELISA. Results were compared with healthy control subjects (CG, n = 26) and the relationship between oxidative stress markers and respiratory symptoms was evaluated. The results of GER treatment and oxidative stress markers in EBC were also correlated.

RESULTS

Twenty-nine patients with a mean age of 8.8 years (3-14 years) were included. The male/female ratio was 16:13. The EA presented with distal fistula in 27 cases. While no fistula was observed in 1 case, both proximal and distal fistulae were present in another single case. Associated anomalies, most of which were cardiovascular anomalies, were observed in 65.5% (n = 19) of cases. The median Glut level was 1.03 mM/ml (0.93-1.15), iso-8 was 38.8 pg/mL (32.03-76.2) and Cys-LT was 0.44 pg/mL (20.17-61.3) in patients with EA. The median levels of oxidative markers in CG were 1.23 mM/mL (1.13-1.36), 66.3 pg/mL (33.5-106.7), and 56.9 pg/mL (27.4-80.1), respectively. Glut levels were significantly lower in EA cases compared to CG (p = 0.01). There was no significant difference between the groups regarding 8-iso and CYS-LT levels (p = 0.9, p = 1.0). Cys-LT levels were significantly lower in patients with PPI treatment [21.7 pg/mL (18.6-48.1)], when compared to patients without PPI treatment [41.1 pg/mL (22.5-83.1)] (p = 0.04) and healthy subjects [56.9 pg/mL (27.4-80.1)] (p = 0.017). The 8-iso levels were significantly decreased in cases with fundoplication compared to the patients without fundoplication (p = 0.02).

CONCLUSION

Glut - an antioxidant agent - levels were significantly lower in EBC of EA cases. The decrease in Cys-LT levels in cases with PPI treatment and in 8-iso levels in patients with fundoplication suggests that the oxidative damage in EBC of EA cases may be correlated with GER and its management.

TYPE OF STUDY

Case control study LEVEL OF EVIDENCE: Level III.

Systems Biology ARDS Research with a Focus on Metabolomics

Acute respiratory distress syndrome (ARDS) is a clinical syndrome that inflicts a considerably heavy toll in terms of morbidity and mortality. While there are multitudes of conditions that can lead to ARDS, the vast majority of ARDS cases are caused by a relatively small number of diseases, especially sepsis and pneumonia. Currently, there is no clinically agreed upon reliable diagnostic test for ARDS, and the detection or diagnosis of ARDS is based on a constellation of laboratory and radiological tests in the absence of evidence of left ventricular dysfunction, as specified by the Berlin definition of ARDS. Virtually all the ARDS biomarkers to date have been proven to be of very limited clinical utility. Given the heterogeneity of ARDS due to the wide variation in etiology, clinical and molecular manifestations, there is a current scientific consensus agreement that ARDS is not just a single entity but rather a spectrum of conditions that need further study for proper classification, the identification of reliable biomarkers and the adequate institution of therapeutic targets. This scoping review aims to elucidate ARDS omics research, focusing on metabolomics and how metabolomics can boost the study of ARDS biomarkers and help to facilitate the identification of ARDS subpopulations.

Evolution of ARDS biomarkers: Will metabolomics be the answer?

To date, there is no clinically agreed-upon diagnostic test for acute respiratory distress syndrome (ARDS): the condition is still diagnosed on the basis of a constellation of clinical findings, laboratory tests, and radiological images. Development of ARDS biomarkers has been in a state of continuous flux during the past four decades. To address ARDS heterogeneity, several studies have recently focused on subphenotyping the disease on the basis of observable clinical characteristics and associated blood biomarkers. However, the strong correlation between identified biomarkers and ARDS subphenotypes has yet to establish etiology; hence, there is a need for the adoption of other methodologies for studying ARDS. In this review, we will shed light on ARDS metabolomics research in the literature and discuss advances and major obstacles encountered in ARDS metabolomics research. Generally, the ARDS metabolomics studies focused on identification of differentiating metabolites for diagnosing ARDS, but they were performed to different standards in terms of sample size, selection of control cohort, type of specimens collected, and measuring technique utilized. Virtually none of these studies have been properly validated to identify true metabolomics biomarkers of ARDS. Though in their infancy, metabolomics studies exhibit promise to unfold the biological processes underlying ARDS and, in our opinion, have great potential for pushing forward our present understanding of ARDS.

Biomarkers in acute lung injury--marking forward progress

This article reviews the state of the art regarding biomarkers for prediction, diagnosis, and prognosis in acute lung injury. Biomarkers and the goals of biomarker research are defined. Progress along 4 general routes is examined. First, the results of wide-ranging existing protein biomarkers are reported. Second, newer biomarkers awaiting or with strong potential for validation are described. Third, progress in the fields of genomics and proteomics is reported. Finally, given the complexity and number of potential biomarkers, the results of combining clinical predictors with protein and other biomarkers to produce better prognostic and diagnostic indices are examined.

Severe hypoxemic respiratory failure: part 1--ventilatory strategies

Approximately 16% of deaths in patients with ARDS results from refractory hypoxemia, which is the inability to achieve adequate arterial oxygenation despite high levels of inspired oxygen or the development of barotrauma. A number of ventilator-focused rescue therapies that can be used when conventional mechanical ventilation does not achieve a specific target level of oxygenation are discussed. A literature search was conducted and narrative review written to summarize the use of high levels of positive end-expiratory pressure, recruitment maneuvers, airway pressure-release ventilation, and high-frequency ventilation. Each therapy reviewed has been reported to improve oxygenation in patients with ARDS. However, none of them have been shown to improve survival when studied in heterogeneous populations of patients with ARDS. Moreover, none of the therapies has been reported to be superior to another for the goal of improving oxygenation. The goal of improving oxygenation must always be balanced against the risk of further lung injury. The optimal time to initiate rescue therapies, if needed, is within 96 h of the onset of ARDS, a time when alveolar recruitment potential is the greatest. A variety of ventilatory approaches are available to improve oxygenation in the setting of refractory hypoxemia and ARDS. Which, if any, of these approaches should be used is often determined by the availability of equipment and clinician bias.