Perceptions of diagnosis and management of patients with acute respiratory distress syndrome: a survey of United Kingdom intensive care physicians

Intensive care physicians' perceptions of the diagnosis & management of patients with acute hypoxic respiratory failure associated with COVID-19: A UK based survey

BACKGROUND

Whilst the management of Coronavirus disease-2019 (COVID-19) has evolved in response to the emerging data, treating such patients remains a challenge, and many treatments lack robust clinical evidence. We conducted a survey to evaluate Intensive Care Unit (ICU) management of COVID-19 patients with acute hypoxic respiratory failure and compared the results with data from a similar survey focusing on Acute Respiratory Distress Syndrome (ARDS) that was conducted in 2013.

METHODS

The questionnaire was refined from a previous survey of ARDS-related clinical practice using an online electronic survey engine (Survey Monkey®) and all UK intensivists were encouraged to participate. The survey was conducted between 16/05/2020 and 17/06/2020.

RESULTS

There were 137 responses from 89 UK centres. Non-invasive ventilation was commonly used in the form of CPAP. The primary ventilation strategy was the ARDSnet protocol, with 63% deviating from its PEEP recommendations. Similar to our previous ARDS survey, most allowed permissive targets for hypoxia (94%), hypercapnia (55%) and pH (94%). The routine use of antibiotics was common, and corticosteroids were frequently used, usually in the context of a clinical trial (45%). Late tracheostomy (>7 days) was preferred (92%). Routine follow-up was offered by 66% with few centres providing routine dedicated rehabilitation programmes following discharge. Compared to the ARDS survey, there is an increased use of neuromuscular agents, APRV ventilation and improved provision of rehabilitation services.

CONCLUSIONS

Similar to our previous ARDS survey, this survey highlights variations in the management strategies used for patients with acute hypoxic respiratory failure due to COVID-19.

Effects of the working experience, educational background, professional titles, and hospital grades of intensive care unit doctors on clinical glucocorticoid use in acute respiratory distress syndrome

ABSTRACT

Although glucocorticoids are commonly used for patients with acute respiratory distress syndrome in the intensive care unit, the exact attitudes of different intensive care unit (ICU) doctors about glucocorticoid usage are largely unknown. Herein, we investigated the practice of glucocorticoid application for acute respiratory distress syndrome (ARDS) by ICU doctors in China. Questionnaires were developed and sent to ICU doctors at 45 hospitals to perform statistics and analysis. ICU doctors with more working experience and professional titles had more knowledge of ARDS. Glucocorticoids were more likely to be used for ARDS caused by chemical inhalation. Doctors with longer working experience, better educational background, and higher professional titles used fewer glucocorticoids. In addition, 97.2%of the doctors considered using methylprednisolone or hydrocortisone first, 50.9% used glucocorticoids within 24hours of onset, and 37.1% insisted that steroid therapy should last 3 to 5days. Although ICU doctors with more working experience and professional titles have a better understanding of glucocorticoid use in ARDS, the majority of clinical practices and attitudes are similar among different doctors regardless of working experience, educational background, professional titles, or hospital grades.

Treatment with 7% and 10% CO2 enhanced expression of IL-1β, TNF-α, and IL-6 in hypoxic cultures of human whole blood

Objective

This study investigated whether hypercapnia influenced the inflammatory response of hypoxic blood.

Methods

Human whole blood was cultured with 0.2% oxygen (O₂) and treated with 5%, 7%, or 10% carbon dioxide (CO₂). Interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-6 were evaluated in whole blood cultures. Reactive oxygen species (ROS) production and expression levels of caspase-1 and IL-1β were evaluated in THP-1 monocytic cells.

Results

IL-1β, TNF-α, and IL-6 levels were higher in the hypoxia + 7% CO₂ group than in the hypoxia + 5% CO₂ group. The hypoxia + 10% CO₂ group had the highest IL-1β, TNF-α, and IL-6 levels, compared with the hypoxia + 7% CO₂ and hypoxia + 5% CO₂ groups. Expression levels of IL-1β, TNF-α, and IL-6 were significantly negatively correlated with pH levels in the cell culture medium. Treatment with 7% and 10% CO₂ increased the production of ROS and the expression of caspase-1 and IL-1β in hypoxia-activated THP-1 cells.

Conclusions

High levels of CO₂ treatment increased expression levels of IL-1β, TNF-α, and IL-6 in hypoxic whole blood cultures. High levels of CO₂-induced ROS overproduction and NLRP3 inflammasome activation in monocytes may comprise a target to mitigate the inflammatory response of hypoxic blood.

Hypercapnia promotes microglial pyroptosis via inhibiting mitophagy in hypoxemic adult rats

Background

Hypoxemia is a typical symptom of acute respiratory distress syndrome. To avoid pulmonary morbidity, low tidal volume ventilation is often applied. The ventilation strategy will certainly cause hypercapnia. This study aimed to explore whether hypercapnia would promote microglial pyroptosis via inhibiting mitophagy in adult rats with hypoxemia.

Methods

The cerebral oxygen extraction ratio (CERO₂) and partial pressure of brain tissue oxygen (PbtO₂) in a rat model of hypercapnia/hypoxemia were assessed. The reactive oxygen species (ROS) production and the expression of LC3‐II/I, p62, caspase‐1, gasdermin D‐N domains (GSDMD‐N), IL‐1β, and IL‐18 in microglial cells were detected.

Results

Hypercapnia decreased the PbtO₂ levels of the hypoxic rats, which was further evidenced by the increased levels of CERO₂. Expression levels of LC3‐II were reduced, while p62 expression was increased by hypercapnia in hypoxic microglia. Hypercapnia increased the production of ROS and the expression of caspase‐1, GSDMD‐N, IL‐1β, and IL‐18 in hypoxia‐activated microglia. Scavenging ROS inhibited microglial pyroptosis and expression of IL‐1β and IL‐18.

Conclusions

These results suggest that hypercapnia‐induced mitophagy inhibition may promote pyroptosis and enhance IL‐1β and IL‐18 release in hypoxia‐activated microglia.

Hypercapnia exacerbates the disruption of the blood‑brain barrier by inducing interleukin‑1β overproduction in the blood of hypoxemic adult rats

Refractory hypoxemia is the main symptom of acute respiratory distress syndrome (ARDS). Low tidal volume ventilation is routinely applied in clinical practice to correct hypoxemia, which aims to prevent ventilator‑induced lung injury. However, this ventilation strategy inevitably leads to hypercapnia. Our previous study demonstrated that hypercapnia aggravated cognitive impairment in hypoxemic rats; however, the underlying mechanism remains unclear. The aim of the present study was to investigate whether hypercapnia exacerbates the blood‑brain barrier (BBB) disruption through inducing interleukin (IL)‑1β overproduction in the blood of hypoxemic rats. The BBB permeability in a rat model of hypercapnia/hypoxemia was evaluated. The levels of IL‑1β in the blood of rats and human whole‑blood cultures were assessed. The expression of IL‑1 receptor 1 (IL‑1R1), phosphorylated IL‑1R1‑associated kinase (p‑IRAK‑1) and tight junctional proteins in cerebral vascular endothelial cells was examined in vitro and in vivo. In addition, IL‑1Ra, an IL‑1 receptor antagonist, was used to determine whether hypercapnia affects tight junctional protein expression in hypoxic cerebral vascular endothelial cells through inducing IL‑1β overproduction. It was observed that hypercapnia alone did not disrupt the BBB, but aggravated the damage to the BBB integrity in hypoxemic rats. Hypercapnia increased IL‑1β expression in the blood of hypoxemic rats as well as in hypoxic human whole‑blood cultures. IL‑1R1 and p‑IRAK‑1 expression was increased, while that of tight junctional proteins was reduced by hypercapnia in hypoxemic cerebral vascular endothelial cells in vitro and in vivo. Additionally, the expression of tight junctional proteins was markedly increased following treatment with IL‑1Ra. These results suggest that hypercapnia‑induced IL‑1β overproduction in the hypoxemic blood may decrease tight junctional protein expression in cerebrovascular endothelial cells via the IL‑1R1/p‑IRAK‑1 pathway, further disrupting BBB integrity, and eventually resulting in increased BBB permeability.

Acceptability of a German multicentre healthcare research study: a survey of research personnels' attitudes, experiences and work load

OBJECTIVES

The DACAPO study as a multicentre nationwide observational healthcare research study investigates the influence of quality of care on the quality of life in patients with acute respiratory distress syndrome. The aim of this study was to investigate the acceptability to the participating research personnels by assessing attitudes, experiences and workload associated with the conduct of the DACAPO study.

DESIGN, SETTING AND PARTICIPANTS

A prospective anonymous online survey was sent via email account to 169 participants in 65 study centres. The questionnaire included six different domains: (1) training for performing the study; (2) obtaining informed consent; (3) data collection; (4) data entry using the online documentation system; (5) opinion towards the study and (6) personal data. Descriptive data analysis was carried out.

RESULTS

A total of 78 participants took part (46%) in the survey, 75 questionnaires (44%) could be evaluated. 51% were senior medical specialists. 95% considered the time frame of the training as appropriate and the presentation was rated by 93% as good or very good. Time effort for obtaining consent, data collection and entry was considered by 41% as a burden. Support from the coordinating study centre was rated as good or very good by more than 90% of respondents. While the DACAPO study was seen as scientifically relevant by 81%, only 45% considered the study results valuable for improving patient care significantly.

CONCLUSION

Collecting feedback on the acceptability of a large multicentre healthcare research study provided important insights. Recruitment and data acquisition was mainly performed by physicians and often regarded as additional time burden in clinical practice. Reducing the amount of data collection and simplifying data entry could facilitate the conduct of healthcare research studies and could improve motivation of researchers in intensive care medicine.

TRIAL REGISTRATION NUMBER

NCT02637011; Pre-results.

Hypercapnia induces IL-1β overproduction via activation of NLRP3 inflammasome: implication in cognitive impairment in hypoxemic adult rats

Background

Cognitive impairment is one of common complications of acute respiratory distress syndrome (ARDS). Increasing evidence suggests that interleukin-1 beta (IL-1β) plays a role in inducing neuronal apoptosis in cognitive dysfunction. The lung protective ventilatory strategies, which serve to reduce pulmonary morbidity for ARDS patients, almost always lead to hypercapnia. Some studies have reported that hypercapnia contributes to the risk of cognitive impairment and IL-1β secretion outside the central nervous system (CNS). However, the underlying mechanism of hypercapnia aggravating cognitive impairment under hypoxia has remained uncertain. This study was aimed to explore whether hypercapnia would partake in increasing IL-1β secretion via activating the NLRP3 (NLR family, pyrin domain-containing 3) inflammasome in the hypoxic CNS and in aggravating cognitive impairment.

Methods

The Sprague-Dawley (SD) rats that underwent hypercapnia/hypoxemia were used for assessment of NLRP3, caspase-1, IL-1β, Bcl-2, Bax, and caspase-3 expression by Western blotting or double immunofluorescence, and the model was also used for Morris water maze test. In addition, Z-YVAD-FMK, a caspase-1 inhibitor, was used to treat BV-2 microglia to determine whether activation of NLRP3 inflammasome was required for the enhancing effect of hypercapnia on expressing IL-1β by Western blotting or double immunofluorescence. The interaction effects were analyzed by factorial ANOVA. Simple effects analyses were performed when an interaction was observed.

Results

There were interaction effects on cognitive impairment, apoptosis of hippocampal neurons, activation of NLRP3 inflammasome, and upregulation of IL-1β between hypercapnia treatment and hypoxia treatment. Hypercapnia + hypoxia treatment caused more serious damage to the learning and memory of rats than those subjected to hypoxia treatment alone. Expression levels of Bcl-2 were reduced, while that of Bax and caspase-3 were increased by hypercapnia in hypoxic hippocampus. Hypercapnia markedly increased the expression of NLRP3, caspase-1, and IL-1β in hypoxia-activated microglia both in vivo and in vitro. Pharmacological inhibition of NLRP3 inflammasome activation and release of IL-1β might ameliorate apoptosis of neurons.

Conclusions

The present results suggest that hypercapnia-induced IL-1β overproduction via activating the NLRP3 inflammasome by hypoxia-activated microglia may augment neuroinflammation, increase neuronal cell death, and contribute to the pathogenesis of cognitive impairments.

Adjuvants to Mechanical Ventilation for Acute Respiratory Failure. Adoption, De-adoption, and Factors Associated with Selection

RATIONALE

Adoption and de-adoption of adjuvant strategies to mechanical ventilation for acute respiratory failure (ARF), and factors associated with their selection, have not been extensively evaluated.

OBJECTIVES

To evaluate change in use of adjuvants to mechanical ventilation for ARF (2008-2013), the impact of landmark publications on adoption and de-adoption, and factors associated with use.

METHODS

Changes in use of four adjuvants for ARF from 2008 to 2013, the impact of landmark publications on use, and factors associated with use were evaluated with the Premier Database. Extracorporeal membrane oxygenation (ECMO), inhaled nitric oxide, inhaled epoprostenol, and continuous neuromuscular blockading agents (cNMBAs) in adult mechanically ventilated patients were identified on the basis of International Classification of Diseases, Ninth Revision, Clinical Modification codes and billing data.

MEASUREMENTS AND MAIN RESULTS

Among 514,913 patients with ARF, 11,567 (2.3%) were treated with at least one adjuvant. cNMBAs were the most frequently used adjuvants (n = 10,073, 2.1% in capable hospitals), followed by inhaled pulmonary vasodilators (n = 1,878, 1.0% in capable hospitals; 58% nitric oxide), and ECMO (n = 195, 0.2% in capable hospitals). There was an increase in ECMO and inhaled epoprostenol over time but no change in nitric oxide or cNMBAs. Segmented regression analysis was used to evaluate whether clinical practice was in accordance with emerging evidence from landmark studies. Using the relevant landmark publication dates, these analyses did not reveal any change in use over time after publication with the exception of inhaled epoprostenol-for which rates of growth decreased over time, possibly in response to the evidence. There was a significant amount of variability in patient and hospital factors associated with use with between adjuvants.

CONCLUSIONS

Between 2008 and 2013, there was an increase in use of ECMO and inhaled epoprostenol, and no change in use of inhaled nitric oxide or continuous intravenous infusion of a neuromuscular blocking agent. There was considerable variability in patient and hospital factors associated with use across different adjuvants.

Inhalation therapies in acute respiratory distress syndrome

The defining features of acute respiratory distress syndrome (ARDS) are an excessive inflammatory respiratory response associated with high morbidity and mortality. Treatment consists mainly of measures to avoid worsening lung injury and cannot reverse the underlying pathophysiological process. New pharmacological agents have shown promising results in preclinical studies; however, they have not been successfully translated to patients with ARDS. The lack of effective therapeutic interventions has resulted in a recent interest in strategies to prevent ARDS with treatments delivering medications directly to the lungs by inhalation and nebulization, hopefully minimizing systemic adverse events. We analyzed the effect of different aerosolized drugs such as bronchodilators, corticosteroids, pulmonary vasodilators, anticoagulants, mucolytics and surfactant. New therapeutic strategies and ongoing trials using carbon monoxide (CO) and AP301 peptide are also briefly reviewed.

One-year experience with an acute respiratory distress syndrome standard operating procedure on intensive care unit

PURPOSE

Mortality in acute respiratory distress syndrome (ARDS) patients remains unacceptable high, and there is substantial variation in the diagnostic and management strategies used. We recently established a standardized algorithm for the early identification and guideline conform therapy of ARDS on intensive care units (ICUs). We here present the results of a first-year observatory period after implementation of the ARDS bundle on our ICU.

METHODS AND RESULTS

A retrospective, observative, single-center case control study over a period of 4 years was performed. We analyzed the effects after implementation of an ARDS standard operating procedure (SOP) on prevalence of the diagnosis ARDS, mortality from ARDS, and therapy strategies. Implementation of the SOP led to an increased frequency of ARDS diagnosis (P < .05), increased application of early prone positioning (P < .05), and use of neuromuscular blockers (P < .02) in ARDS patients. An influence on mortality in ARDS patients could not be detected after implementation of the SOP (P = not significant).

CONCLUSION

A standardized ARDS bundle fundamentally increases awareness of this clinical picture on ICU and facilitates application of evidence-based therapies like prone positioning and use of neuromuscular blockers. These data encourage evaluating our ARDS SOP in a prospective trial to identify potential effects on mortality.

A national survey of the diagnosis and management of suspected ventilator-associated pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) affects up to 20% of patients admitted to intensive care units (ICU). It is associated with increased morbidity, mortality and healthcare costs. Despite published guidelines, variability in diagnosis and management exists, the extent of which remains unclear. We sought to characterise consultant opinions surrounding diagnostic and management practice for VAP in the UK.

METHODS

An online survey was sent to all consultant members of the UK Intensive Care Society (n=∼1500). Data were collected regarding respondents' individual practice in the investigation and management of suspected VAP including use of diagnostic criteria, microbiological sampling, chest X-ray (CXR), bronchoscopy and antibiotic treatments.

RESULTS

339 (23%) responses were received from a broadly representative spectrum of ICU consultants. All respondents indicated that microbiological confirmation should be sought, the majority (57.8%) stating they would take an endotracheal aspirate prior to starting empirical antibiotics. Microbiology reporting services were described as qualitative only by 29.7%. Only 17% of respondents had access to routine reporting of CXRs by a radiologist. Little consensus exists regarding technique for bronchoalveolar lavage (BAL) with the reported volume of saline used ranging from 5 to 500 mL. 24.5% of consultants felt inadequately trained in bronchoscopy.

CONCLUSIONS

There is wide variability in the approach to diagnosis and management of VAP among UK consultants. Such variability challenges the reliability of the diagnosis of VAP and its reported incidence as a performance indicator in healthcare systems. The data presented suggest increased radiological and microbiological support, and standardisation of BAL technique, might improve this situation.