Precision Medicine Using Simultaneous Monitoring and Assessment with Imaging and Biomarkers to Manage Mechanical Ventilation in ARDS

Physiologic Comparison of Airway Pressure Release Ventilation and Low Tidal Volume Ventilation in ARDS: A Randomized Controlled Trial

BACKGROUND

The physiologic effects of different ventilation strategies on patients with ARDS)need to be understood better.

RESEARCH QUESTION

In patients with ARDS receiving controlled mandatory ventilation, does airway pressure release ventilation (APRV) improve lung ventilation/perfusion (V˙/Q˙) matching and ventilation homogeneity compared with low tidal volume (LTV) ventilation?

STUDY DESIGN AND METHODS

This study was a single-center randomized controlled trial. Patients with moderate to severe ARDS were ventilated randomly with APRV or LTV ventilation. Electrical impedance tomography (EIT) was used to assess lung ventilation and perfusion. EIT-based data and clinical variables related to respiratory and hemodynamic conditions were collected shortly before randomization (0 hours) and at 12 and 24 hours after randomization.

RESULTS

A total of 40 patients were included and randomized to the APRV or LTV ventilation group (20 per group). During the 24-hour trial period, patients receiving APRV exhibited significantly increased dorsal ventilation (difference value [24 hours minus 0 hours]: median, 10.82% [interquartile range (IQR), 2.62%-13.74%] vs 0.12% [IQR, -2.81% to 4.76%]; P = .017), decreased dorsal shunt (median, -4.67% [IQR, -6.83% to 0.59%] vs 1.73% [IQR, -0.95% to 5.53%]; P = .008), and increased dorsal V˙/Q˙ matching (median, 4.13% [IQR, -0.26% to 10.47%] vs -3.29% [IQR, -5.05% to 2.81%]; P = .026) than those receiving LTV ventilation. No difference in ventral dead space was observed between study groups (P = .903). Additionally, 2 indicators of ventilation distribution heterogeneity, global inhomogeneity index and center of ventilation, significantly decreased and significantly increased, respectively, in the APRV group compared with the LTV ventilation group. Patients receiving APRV showed significantly higher Pao2 to Fio2 ratio, higher respiratory system static compliance (Crs) and lower Paco2 than those receiving LTV ventilation at 24 hours. The cardiac output was comparable in both groups.

INTERPRETATION

APRV, as compared with LTV ventilation, could recruit dorsal region, reduce dorsal shunt, increase dorsal V˙/Q˙ matching, and improve ventilation homogeneity of the lungs, leading to better gas exchange and Crs in patients with moderate to severe ARDS.

CLINICAL TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT05767125; URL: www.

CLINICALTRIALS

gov.

Management of severe acute respiratory distress syndrome in Australia and New Zealand (SAGE-ANZ): An observational study

Objective

Acute respiratory distress syndrome (ARDS) is associated with significant mortality, morbidity, and cost. We aimed to describe characteristics and management of adult patients admitted to intensive care units (ICUs) in Australia and New Zealand with moderate-severe ARDS, to better understand contemporary practice.

Design

Bi-national, prospective, observational, multi-centre study.

Setting

19 ICUs in Australia and New Zealand.

Participants

Mechanically ventilated patients with moderate-severe ARDS.

Main outcome measures

Baseline demographic characteristics, ventilation characteristics, use of adjunctive support therapy and all-cause mortality to day 28. Data were summarised using descriptive statistics.

Results

200 participants were enrolled, mean (±SD) age 55.5 (±15.9) years, 40% (n = 80) female. Around half (51.5%) had no baseline comorbidities and 45 (31%) tested positive for COVID-19. On day 1, mean SOFA score was 9 ± 3; median (IQR) PaO2/FiO2 ratio 119 (89, 142), median (IQR) FiO2 70% (50%, 99%) and mean (±SD) positive end expiratory pressure (PEEP) 11 (±3) cmH2O. On day one, 10.5% (n = 21) received lung protective ventilation (LPV) (tidal volume ≤6.5 mL/kg predicted body weight and plateau pressure or peak pressure ≤30 cm H2O). Adjunctive therapies were received by 86% (n = 172) of patients at some stage from enrolment to day 28. Systemic steroids were most used (n = 127) followed by neuromuscular blockers (n = 122) and prone positioning (n = 27). Median ventilator-free days (IQR) to day 28 was 5 (0, 20). In-hospital mortality, censored at day 28, was 30.5% (n = 61).

Conclusions

In Australia and New Zealand, compliance with evidence-based practices including LPV and prone positioning was low in this cohort. Therapies with proven benefit in the treatment of patients with moderate-severe ARDS, such as lung protective ventilation and prone positioning, were not routinely employed.

Proprotein Convertase Subtilisin/Kexin Type 9 Induction in COVID-19 Is Poorly Associated with Disease Severity and Cholesterol Levels

SARS-CoV-2 infection was shown to induce proprotein convertase subtilisin/kexin type 9 (PCSK9) plasma levels in sepsis. Here, we investigate the association between serum PCSK9 levels and disease severity. PCSK9 was measured in serum of 55 controls, 40 patients with moderate and 60 patients with severe COVID-19 disease. Serum PCSK9 was elevated in moderate COVID-19 compared to controls and further increased in severe cases. PCSK9 levels were not associated with C-reactive protein, bacterial superinfections, interventions, or survival in patients with severe COVID-19. PCSK9 regulates circulating cholesterol levels, and 15 cholesteryl ester (CE) species and free cholesterol (FC) were quantified by direct flow injection analysis using a high-resolution hybrid quadrupole-Orbitrap mass spectrometer. Most CE species with shorter fatty acid chains were decreased in severe compared to moderate COVID-19, and none of the CE species were correlated with PCSK9 in patients with severe COVID-19. Levels of all CE species negatively correlated with C-reactive protein in severe COVID-19 patients. Notably, FC was induced in severe compared to moderate COVID-19. The FC/CE ratio correlated positively with inflammatory markers and was associated with non-survival. The current study suggests that the imbalance between CE and FC levels is associated with disease severity and mortality in patients with COVID-19.

Effects of mechanical ventilation on the interstitial extracellular matrix in healthy lungs and lungs affected by acute respiratory distress syndrome: a narrative review

BACKGROUND

Mechanical ventilation, a lifesaving intervention in critical care, can lead to damage in the extracellular matrix (ECM), triggering inflammation and ventilator-induced lung injury (VILI), particularly in conditions such as acute respiratory distress syndrome (ARDS). This review discusses the detailed structure of the ECM in healthy and ARDS-affected lungs under mechanical ventilation, aiming to bridge the gap between experimental insights and clinical practice by offering a thorough understanding of lung ECM organization and the dynamics of its alteration during mechanical ventilation.

MAIN TEXT

Focusing on the clinical implications, we explore the potential of precise interventions targeting the ECM and cellular signaling pathways to mitigate lung damage, reduce inflammation, and ultimately improve outcomes for critically ill patients. By analyzing a range of experimental studies and clinical papers, particular attention is paid to the roles of matrix metalloproteinases (MMPs), integrins, and other molecules in ECM damage and VILI. This synthesis not only sheds light on the structural changes induced by mechanical stress but also underscores the importance of cellular responses such as inflammation, fibrosis, and excessive activation of MMPs.

CONCLUSIONS

This review emphasizes the significance of mechanical cues transduced by integrins and their impact on cellular behavior during ventilation, offering insights into the complex interactions between mechanical ventilation, ECM damage, and cellular signaling. By understanding these mechanisms, healthcare professionals in critical care can anticipate the consequences of mechanical ventilation and use targeted strategies to prevent or minimize ECM damage, ultimately leading to better patient management and outcomes in critical care settings.

Serum Adiponectin Predicts COVID-19 Severity

Adiponectin is primarily known for its protective role in metabolic diseases, and it also possesses immunoregulatory properties. Elevated levels of adiponectin have been observed in various inflammatory diseases. However, studies investigating adiponectin levels in the serum of COVID-19 patients have yielded conflicting results. This study aimed to assess serum adiponectin levels in 26 healthy controls, as well as in 64 patients with moderate and 60 patients with severe COVID-19, to determine a potential association between serum adiponectin and the severity of COVID-19. Serum adiponectin levels in severe COVID-19 patients were significantly lower than in those with moderate disease and healthy controls, who exhibited similar serum adiponectin levels. Among patients with moderate disease, positive correlations were observed between serum adiponectin and C-reactive protein levels. Of note, serum adiponectin levels of severe COVID-19 cases were comparable between patients with and without dialysis or vasopressor therapy. Superinfection with bacteria did not exert a notable influence on serum adiponectin levels in patients with severe disease. Patients who were diagnosed with severe COVID-19 and vancomycin-resistant enterococci bacteremia showed a significant reduction in their serum adiponectin levels. An analysis conducted on the entire cohort, including both moderate and severe COVID-19 patients, showed that individuals who did not survive had lower serum adiponectin levels when compared to those who survived. In summary, this study highlights a decrease in serum adiponectin levels in severe COVID-19 cases, indicating the potential utility of adiponectin as an additional biomarker for monitoring disease severity in COVID-19 or critical illnesses in general.

Serum Insulin-like Growth Factor-Binding Protein-2 as a Prognostic Factor for COVID-19 Severity

Insulin-like growth factor-binding protein (IGFBP)-2 is a regulator of anabolic pathways, which become inactivated in severe illness. Here, we measured the serum IGFBP-2 levels of COVID-19 patients with moderate and severe disease as well as healthy controls to identify the associations of serum IGFBP-2 levels with disease severity. Patients with severe COVID-19 had higher serum IGFBP-2 levels than those with moderate disease and healthy controls, who had similar levels. Non-survivors of COVID-19 tended to have elevated serum IGFBP-2 levels compared to survivors. Increased serum IGFBP-2 levels were observed in patients requiring dialysis and vasopressor therapy. Serum IGFBP-2 was positively correlated with procalcitonin in both patient groups. Bacterial co-infection in severe COVID-19 patients did not influence serum IGFBP-2 levels. Patients with liver cirrhosis and obesity, showing increased and decreased serum IGFBP-2 levels, respectively, were excluded from the study. The present analysis showed that higher serum IGFBP-2 levels are associated with increased disease severity in COVID-19 patients. The similarity in serum IGFBP-2 levels between patients with moderate COVID-19 and healthy controls suggests that elevated IGFBP-2 is associated with critical illness rather than SARS-CoV-2 infection itself.

Redefining ARDS: a paradigm shift

Although the defining elements of "acute respiratory distress syndrome" (ARDS) have been known for over a century, the syndrome was first described in 1967. Since then, despite several revisions of its conceptual definition, it remains a matter of debate whether ARDS is a discrete nosological entity. After almost 60 years, it is appropriate to examine how critical care has modeled this fascinating syndrome and affected patient's outcome. Given that the diagnostic criteria of ARDS (e.g., increased pulmonary vascular permeability and diffuse alveolar damage) are difficult to ascertain in clinical practice, we believe that a step forward would be to standardize the assessment of pulmonary and extrapulmonary involvement in ARDS to ensure that each patient can receive the most appropriate and effective treatment. The selection of treatments based on arbitrary ranges of PaO2/FiO2 lacks sufficient sensitivity to individualize patient care.