Evolution of practice patterns in the management of acute respiratory distress syndrome: A secondary analysis of two successive randomized controlled trials

Investigational pharmacological agents for the treatment of ARDS

INTRODUCTION

Acute Respiratory Distress Syndrome (ARDS) is a heterogeneous form of lung injury with severe hypoxemia and bilateral infiltrates after an inciting event that results in diffuse lung inflammation with a high mortality rate. While research in COVID-related ARDS has resulted in several pharmacotherapeutic agents that have undergone successful investigation, non-COVID ARDS studies have not resulted in many widely accepted pharmacotherapeutic agents despite exhaustive research.

AREAS COVERED

The aim of this review is to discuss adjuvant pharmacotherapies targeting non-COVID Acute Lung Injury (ALI)/ARDS and novel therapeutics in COVID associated ALI/ARDS. In ARDS, variable data may support selective use of neuromuscular blocking agents, corticosteroids and neutrophil elastase inhibitors, but are not yet universally used. COVID-ALI/ARDS has data supporting the use of IL-6 monoclonal antibodies, corticosteroids, and JAK inhibitor therapy.

EXPERT OPINION

Although ALI/ARDS modifying pharmacological agents have been identified in COVID-related disease, the data in non-COVID ALI/ARDS has been less compelling. The increased use of more specific molecular phenotyping based on physiologic parameters and biomarkers, will ensure equipoise between groups, and will likely allow more precision in confirming pharmacological agent efficacy in future studies.

An Update on Management of Adult Patients with Acute Respiratory Distress Syndrome: An Official American Thoracic Society Clinical Practice Guideline

Background: This document updates previously published Clinical Practice Guidelines for the management of patients with acute respiratory distress syndrome (ARDS), incorporating new evidence addressing the use of corticosteroids, venovenous extracorporeal membrane oxygenation, neuromuscular blocking agents, and positive end-expiratory pressure (PEEP). Methods: We summarized evidence addressing four "PICO questions" (patient, intervention, comparison, and outcome). A multidisciplinary panel with expertise in ARDS used the Grading of Recommendations, Assessment, Development, and Evaluation framework to develop clinical recommendations. Results: We suggest the use of: 1) corticosteroids for patients with ARDS (conditional recommendation, moderate certainty of evidence), 2) venovenous extracorporeal membrane oxygenation in selected patients with severe ARDS (conditional recommendation, low certainty of evidence), 3) neuromuscular blockers in patients with early severe ARDS (conditional recommendation, low certainty of evidence), and 4) higher PEEP without lung recruitment maneuvers as opposed to lower PEEP in patients with moderate to severe ARDS (conditional recommendation, low to moderate certainty), and 5) we recommend against using prolonged lung recruitment maneuvers in patients with moderate to severe ARDS (strong recommendation, moderate certainty). Conclusions: We provide updated evidence-based recommendations for the management of ARDS. Individual patient and illness characteristics should be factored into clinical decision making and implementation of these recommendations while additional evidence is generated from much-needed clinical trials.

American Association for the Surgery of Trauma/American College of Surgeons Committee on Trauma clinical protocol for management of acute respiratory distress syndrome and severe hypoxemia

LEVEL OF EVIDENCE

Therapeutic/Care Management: Level V.

Genetic Determinants of the Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a life-threatening lung condition that arises from multiple causes, including sepsis, pneumonia, trauma, and severe coronavirus disease 2019 (COVID-19). Given the heterogeneity of causes and the lack of specific therapeutic options, it is crucial to understand the genetic and molecular mechanisms that underlie this condition. The identification of genetic risks and pharmacogenetic loci, which are involved in determining drug responses, could help enhance early patient diagnosis, assist in risk stratification of patients, and reveal novel targets for pharmacological interventions, including possibilities for drug repositioning. Here, we highlight the basis and importance of the most common genetic approaches to understanding the pathogenesis of ARDS and its critical triggers. We summarize the findings of screening common genetic variation via genome-wide association studies and analyses based on other approaches, such as polygenic risk scores, multi-trait analyses, or Mendelian randomization studies. We also provide an overview of results from rare genetic variation studies using Next-Generation Sequencing techniques and their links with inborn errors of immunity. Lastly, we discuss the genetic overlap between severe COVID-19 and ARDS by other causes.

Impact of pharmacological interventions on intrapulmonary shunt during one-lung ventilation in adult thoracic surgery: a systematic review and component network meta-analysis

BACKGROUND

Intrapulmonary shunt is a major determinant of oxygenation in thoracic surgery under one-lung ventilation. We reviewed the effects of available treatments on shunt, Pao₂/FiO₂ and haemodynamics through systematic review and network meta-analysis.

METHODS

Online databases were searched for RCTs comparing pharmacological interventions and intrapulmonary shunt in thoracic surgery under one-lung ventilation up to March 30, 2022. Random-effects (component) network meta-analysis compared 24 treatments and 19 treatment components. The Confidence in Network Meta-Analysis (CINeMA) framework assessed evidence certainty. The primary outcome was intrapulmonary shunt fraction during one-lung ventilation.

RESULTS

A total of 55 RCTs were eligible for systematic review (2788 participants). The addition of N₂O (mean difference [MD]=-15%; 95% confidence interval [CI], -25 to -5; P=0.003) or almitrine (MD=-13%; 95% CI, -20 to -6; P<0.001) to propofol anaesthesia were efficient at decreasing shunt. Combined epidural anaesthesia (MD=3%; 95% CI, 1-5; P=0.005), sevoflurane (MD=5%; 95% CI, 2-8; P<0.001), isoflurane (MD=6%; 95% CI, 4-9; P<0.001), and desflurane (MD=9%; 95% CI, 4-14; P=0.001) increased shunt vs propofol. Almitrine (MD=147 mm Hg; 95% CI, 58-236; P=0.001), dopexamine (MD=88 mm Hg; 95% CI, 4-171; P=0.039), and iloprost (MD=81 mm Hg; 95% CI, 4-158; P=0.038) improved Pao₂/FiO₂. Certainty of evidence ranged from very low to moderate.

CONCLUSIONS

Adding N₂O or almitrine to propofol anaesthesia reduced intrapulmonary shunt during one-lung ventilation. Halogenated anaesthetics increased shunt in comparison with propofol. The effects of N₂O, iloprost, and dexmedetomidine should be investigated in future research. N₂O results constitute a research hypothesis currently not backed by any direct evidence. The clinical availability of almitrine is limited.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42022310313.

Personalized medicine targeting different ARDS phenotypes: The future of pharmacotherapy for ARDS?

INTRODUCTION

Acute respiratory distress syndrome (ARDS) still represents a major challenge with high mortality rates and altered quality of life. Many well-designed studies have failed to improve ARDS outcomes. Heterogeneity of etiologies, mechanisms of lung damage, different lung mechanics, and different treatment approaches may explain these failures. At the era of personalized medicine, ARDS phenotyping is not only a field of research, but a bedside consideration when implementing therapy. ARDS has moved from being a simple syndrome to a more complex area of subgrouping. Intensivists must understand these phenotypes and therapies associated with a better outcome.

AREAS COVERED

After a brief sum-up of the different type of ARDS phenotypes, we will present some relevant therapy that may be impacted by phenotyping. A focus on pharmacotherapy will be realized before a section on non-pharmaceutical strategies. Eventually, we will highlight the limits of our knowledge of phenotyping and the pitfalls of personalized medicine.

EXPERT OPINION

Biological and morphological ARDS phenotypes are now well studied. The future of ARDS therapy will go through phenotyping that allows a personalized medication for each patient. However, a better assessment of these phenotypes is required, and clinical trials should be conducted with an ad-hoc phenotyping before randomization.

The Physiological Basis of High-Frequency Oscillatory Ventilation and Current Evidence in Adults and Children: A Narrative Review

High-frequency oscillatory ventilation (HFOV) is a type of invasive mechanical ventilation that employs supra-physiologic respiratory rates and low tidal volumes (V_T) that approximate the anatomic deadspace. During HFOV, mean airway pressure is set and gas is then displaced towards and away from the patient through a piston. Carbon dioxide (CO₂) is cleared based on the power (amplitude) setting and frequency, with lower frequencies resulting in higher V_T and CO₂ clearance. Airway pressure amplitude is significantly attenuated throughout the respiratory system and mechanical strain and stress on the alveoli are theoretically minimized. HFOV has been purported as a form of lung protective ventilation that minimizes volutrauma, atelectrauma, and biotrauma. Following two large randomized controlled trials showing no benefit and harm, respectively, HFOV has largely been abandoned in adults with ARDS. A multi-center clinical trial in children is ongoing. This article aims to review the physiologic rationale for the use of HFOV in patients with acute respiratory failure, summarize relevant bench and animal models, and discuss the potential use of HFOV as a primary and rescue mode in adults and children with severe respiratory failure.