Kathryn Hibbert

Obesity and ARDS

Obesity prevalence continues to increase globally, with figures exceeding 30% of some populations. Patients who are obese experience alterations in baseline pulmonary mechanics, including airflow obstruction, decreased lung volumes, and impaired gas exchange. These physiologic changes have implications in many diseases, including ARDS. The unique physiology of patients who are obese affects the presentation and pathophysiology of ARDS, and patients who are obese who have respiratory failure present specific management challenges. Although more study is forthcoming, ventilator strategies that focus on transpulmonary pressure as a measure of lung stress show promise in pilot studies. Given the increasing prevalence of obesity and the variable effects of obesity on respiratory mechanics and ARDS pathophysiology, we recommend an individualized approach to the management of the obese patient with ARDS.

High-flow oxygen therapy and other inhaled therapies in intensive care units

In this Series paper, we review the current evidence for the use of high-flow oxygen therapy, inhaled gases, and aerosols in the care of critically ill patients. The available evidence supports the use of high-flow nasal cannulae for selected patients with acute hypoxaemic respiratory failure. Heliox might prevent intubation or improve gas flow in mechanically ventilated patients with severe asthma. Additionally, it might improve the delivery of aerosolised bronchodilators in obstructive lung disease in general. Inhaled nitric oxide might improve outcomes in a subset of patients with postoperative pulmonary hypertension who had cardiac surgery; however, it has not been shown to provide long-term benefit in patients with acute respiratory distress syndrome (ARDS). Inhaled prostacyclins, similar to inhaled nitric oxide, are not recommended for routine use in patients with ARDS, but can be used to improve oxygenation in patients who are not adequately stabilised with traditional therapies. Aerosolised bronchodilators are useful in mechanically ventilated patients with asthma and chronic obstructive pulmonary disease, but are not recommended for those with ARDS. Use of aerosolised antibiotics for ventilator-associated pneumonia and ventilator-associated tracheobronchitis shows promise, but the delivered dose can be highly variable if proper attention is not paid to the delivery method.

The hidden curriculum in radiology residency programs: A path to isolation or integration?

PURPOSE In this qualitative case study involving five academic Radiology centres across Canada, the authors seek to identify the hidden curriculum. METHODS A qualitative case study methodology was used for its potential to explore and provide rich descriptions and allow for the in-depth analysis of multiple data sources that include official institutional documents, surveys, observations and interviews (including undergraduate students, postgraduate, radiologists, imaging scientists, residents, faculty and administrators). This study relied on 48 interviews and involved primary data analysis by the core research team, and a secondary analysis by external examiners. RESULTS The results revealed that in four of the five major centres studied, a hidden curriculum of isolation prevailed, reinforcing an image of the radiologist as an independent operator within an organization dependent upon collaboration for optimal performance. The fifth site exhibited a hidden curriculum of collaboration and support, although the messages received were conflicting when addressing issues around teaching. CONCLUSIONS The authors conclude by noting two possibilities for medical imaging departments to consider that of isolation or that of integration. They examine the implications of each and propose a way forward that situates Radiology as the crossroads of medicine. As such, the need for a new, generative metaphor reasserts the importance of recognizing the role and function of scholarship in teaching and learning contexts across Canada.

Hypoxic Pulmonary Vasoconstriction Does Not Explain All Regional Perfusion Redistribution in Asthma

Rationale: Regional hypoventilation in bronchoconstricted patients with asthma is spatially associated with reduced perfusion, which is proposed to result from hypoxic pulmonary vasoconstriction (HPV). Objectives: To determine the role of HPV in the regional perfusion redistribution in bronchoconstricted patients with asthma. Methods: Eight patients with asthma completed positron emission tomographic/computed tomographic lung imaging at baseline and after bronchoconstriction, breathing either room air or 80% oxygen (80% O2) on separate days. Relative perfusion, specific ventilation (sV), and gas fraction (Fgas) in the 25% of the lung with the lowest specific ventilation (sVlow) and the remaining lung (sVhigh) were quantified and compared. Measurements and Main Results: In the sVlow region, bronchoconstriction caused a significant decrease in sV under both room air and 80% O2 conditions (baseline vs. bronchoconstriction, mean ± SD, 1.02 ± 0.20 vs. 0.35 ± 0.19 and 1.03 ± 0.20 vs. 0.32 ± 0.16, respectively; P < 0.05). In the sVlow region, relative perfusion decreased after bronchoconstriction under room air conditions and also, to a lesser degree, under 80% O2 conditions (1.02 ± 0.19 vs. 0.72 ± 0.08 [P < 0.001] and 1.08 ± 0.19 vs. 0.91 ± 0.12 [P < 0.05], respectively). The Fgas increased after bronchoconstriction under room air conditions only (0.99 ± 0.04 vs. 1.00 ± 0.02; P < 0.05). The sVlow subregion analysis indicated that some of the reduction in relative perfusion after bronchoconstriction under 80% O2 conditions occurred as a result of the presence of regional hypoxia. However, relative perfusion was also significantly reduced in sVlow subregions that were hyperoxic under 80% O2 conditions. Conclusions: HPV is not the only mechanism that contributes to perfusion redistribution in bronchoconstricted patients with asthma, suggesting that another nonhypoxia mechanism also contributes. We propose that this nonhypoxia mechanism may be either direct mechanical interactions and/or unidentified intercellular signaling between constricted airways, the parenchyma, and the surrounding vasculature.

Risk factors and outcomes associated with new-onset atrial fibrillation during acute respiratory distress syndrome ☆ ☆☆

PURPOSE Outcomes and risk factors associated with new-onset atrial fibrillation (AF) during acute respiratory distress syndrome (ARDS) are unclear. We investigated mortality and risk factors associated with new-onset AF during ARDS. MATERIALS AND METHODS We obtained data from the ARDS Network Albuterol for Treatment of Acute Lung Injury trial, which prospectively identified new-onset AF among patients with ARDS as an adverse event. We determined Acute Physiology and Chronic Health Evaluation III-adjusted associations between new-onset AF and 90-day mortality. We also examined associations between new-onset AF and markers of inflammation (interleukin 6 and interleukin 8), myocardial injury (troponin I), autonomic activation (epinephrine), and atrial stretch (central venous pressure) as well as other clinical characteristics. MEASUREMENTS AND MAIN RESULTS Of 282 patients (mean age, 51.6 years; 45% women; 77% white) enrolled in Albuterol for Treatment of Acute Lung Injury, 28 (10%) developed new-onset AF during the study. We did not identify associations between new-onset AF and baseline central venous pressure, plasma levels of troponin I, epinephrine, interleukin 6, or interleukin 8. New-onset AF during ARDS was associated with increased 90-day mortality (new-onset AF, 43% vs no new-onset AF, 19%; Acute Physiology and Chronic Health Evaluation-adjusted odds ratio, 3.09 [95% confidence interval, 1.24-7.72]; P = .02). CONCLUSION New-onset AF during ARDS is associated with increased mortality; however, its mechanisms require further study.

Plasma Concentrations of Soluble Suppression of Tumorigenicity-2 and Interleukin-6 Are Predictive of Successful Liberation From Mechanical Ventilation in Patients With the Acute Respiratory Distress Syndrome*

Objectives: Soluble suppression of tumorigenicity-2 and interleukin-6 concentrations have been associated with the inflammatory cascade of acute respiratory distress syndrome. We determined whether soluble suppression of tumorigenicity-2 and interleukin-6 levels can be used as prognostic biomarkers to guide weaning from mechanical ventilation and predict the need for reintubation. Design, Setting, and Patients: We assayed plasma soluble suppression of tumorigenicity-2 (n = 826) concentrations and interleukin-6 (n = 755) concentrations in the Fluid and Catheter Treatment Trial, a multicenter randomized controlled trial of conservative fluid management in acute respiratory distress syndrome. We tested whether soluble suppression of tumorigenicity-2 and interleukin-6 levels were associated with duration of mechanical ventilation, the probability of passing a weaning assessment, and the need for reintubation. Measurements and Main Results: In models adjusted for Acute Physiology and Chronic Health Evaluation score and other relevant variables, patients with higher day 0 and day 3 median soluble suppression of tumorigenicity-2 and interleukin-6 concentrations had decreased probability of extubation over time (day 0 soluble suppression of tumorigenicity-2: hazard ratio, 0.85; 95% CI, 0.72–1.00; p = 0.05; day 0 interleukin-6: hazard ratio, 0.64; 95% CI, 0.54–0.75; p < 0.0001; day 3 soluble suppression of tumorigenicity-2: hazard ratio, 0.64; 95% CI, 0.54–0.75; p < 0.0001; and day 3 interleukin-6: hazard ratio, 0.73; 95% CI, 0.62–0.85; p = 0.0001). Higher biomarker concentrations were also predictive of decreased odds of passing day 3 weaning assessments (soluble suppression of tumorigenicity-2: odds ratio, 0.62: 95% CI, 0.44–0.87; p = 0.006 and interleukin-6: odds ratio, 0.61; 95% CI, 0.43–0.85; p = 0.004) and decreased odds of passing a spontaneous breathing trial (soluble suppression of tumorigenicity-2: odds ratio, 0.45; 95% CI, 0.28–0.71; p = 0.0007 and interleukin-6 univariate analysis only: odds ratio, 0.55; 95% CI, 0.36–0.83; p = 0.005). Finally, higher biomarker levels were significant predictors of the need for reintubation for soluble suppression of tumorigenicity-2 (odds ratio, 3.23; 95% CI, 1.04–10.07; p = 0.04) and for interleukin-6 (odds ratio, 2.58; 95% CI, 1.14–5.84; p = 0.02). Conclusions: Higher soluble suppression of tumorigenicity-2 and interleukin-6 concentrations are each associated with worse outcomes during weaning of mechanical ventilation and increased need for reintubation in patients with acute respiratory distress syndrome. Biomarker-directed ventilator management may lead to improved outcomes in weaning of mechanical ventilation in patients with acute respiratory distress syndrome.

Deterioration of Regional Lung Strain and Inflammation during Early Lung Injury

Rationale: The contribution of aeration heterogeneity to lung injury during early mechanical ventilation of uninjured lungs is unknown. Objectives: To test the hypotheses that a strategy consistent with clinical practice does not protect from worsening in lung strains during the first 24 hours of ventilation of initially normal lungs exposed to mild systemic endotoxemia in supine versus prone position, and that local neutrophilic inflammation is associated with local strain and blood volume at global strains below a proposed injurious threshold. Methods: Voxel‐level aeration and tidal strain were assessed by computed tomography in sheep ventilated with low Vt and positive end‐expiratory pressure while receiving intravenous endotoxin. Regional inflammation and blood volume were estimated from 2‐deoxy‐2‐[(18)F]fluoro‐d‐glucose (18F‐FDG) positron emission tomography. Measurements and Main Results: Spatial heterogeneity of aeration and strain increased only in supine lungs (P < 0.001), with higher strains and atelectasis than prone at 24 hours. Absolute strains were lower than those considered globally injurious. Strains redistributed to higher aeration areas as lung injury progressed in supine lungs. At 24 hours, tissue‐normalized 18F‐FDG uptake increased more in atelectatic and moderately high‐aeration regions (>70%) than in normally aerated regions (P < 0.01), with differential mechanistically relevant regional gene expression. 18F‐FDG phosphorylation rate was associated with strain and blood volume. Imaging findings were confirmed in ventilated patients with sepsis. Conclusions: Mechanical ventilation consistent with clinical practice did not generate excessive regional strain in heterogeneously aerated supine lungs. However, it allowed worsening of spatial strain distribution in these lungs, associated with increased inflammation. Our results support the implementation of early aeration homogenization in normal lungs.

The practice of radiology education

A solution to get the problem off, have you found it? Really? What kind of solution do you resolve the problem? From what sources? Well, there are so many questions that we utter every day. No matter how you will get the solution, it will mean better. You can take the reference from some books. And the the practice of radiology education is one book that we really recommend you to read, to get more solutions in solving this problem.

Co-Constructed by Design: Knowledge Processes in a Fluid “Cloud Curriculum”

Two concurrent trends converge in contemporary education: the first acknowledges educational activities as social and situated prompting us to imagine new roles for community in teaching and learning; the second attends to our abilities to differentiate and individualize activities, to be responsive to learner needs. Multiliteracies theorists contend that learning can be understood as a process of “weaving” backward and forward across and between different pedagogical moves. Using “knowledge processes” as a theoretical lens, we explore the pedagogical moves possible when we take an award winning curricular approach to teaching Shakespeare and work with it in the context of a dynamic “cloud”; a generative, flexible and participatory space where learners, educators and developers are integral to the process of “curriculum making. ” We offer examples of the multiple opportunities for the pedagogies of “new teacher” and “new learning” to emerge when a space for invention is created.

Corrigendum to: "Risk factors and outcomes associated with new-onset atrial fibrillation during acute respiratory distress syndrome" [J Crit Care 2015;30(5):994-997].

a Department of Internal Medicine, Section of Hospital Medicine, Umass Memorial Medical Center, Worcester, MA b Department of Medicine, Division of General Internal Medicine, Boston University School of Medicine, Boston, MA c Department of Medicine, Section of Cardiovascular Medicine and Preventive Medicine, Boston University School of Medicine, Boston, MA d Department of Medicine, Pulmonary and Critical Care Unit, Massachusetts General Hospital, Boston, MA e Department of Medicine, Section of Pulmonary and Critical Care, The Pulmonary Center, Boston University School of Medicine, Boston, MA