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"Richard, Jean-Christophe"
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The politics of war : Canada's Afghanistan mission, 2001-14
\"When the Canadian government committed forces to join the American-led military mission in Afghanistan following the terrorist attacks of September 11, 2001, little did Canadians--or the government itself--foresee that this decision would involve Canada in a war-riven country for over a decade. The Politics of War explores how, as the mission became increasingly unpopular, Canadian politicians across the political spectrum began to use it to score political points against their opponents. This was \"politics\" with a vengeance. Through historical analysis of the public record and interviews with officials, Jean-Christophe Boucher and Kim Richard Nossal show how the Canadian government sought to frame the engagement in Afghanistan as a \"mission\" rather than what it was--a war. They examine the efforts of successive governments to convince Canadians of the rightness of Canada's engagement in Afghanistan, the parliamentary politics that resulted from the increasing politicization of the mission, and the impact of public opinion on Canada's engagement. They argue that the direction, duration, and nature of Canada's contribution to international stabilization efforts in Afghanistan were largely determined by domestic, politically motivated factors rather than by what was happening in Afghanistan itself. This contribution to the field of Canadian foreign policy analyzes the impact of political elites, parliament, and public opinion on the mission and demonstrates how much of Canada's long war in Afghanistan was shaped by the vagaries of domestic politics and political gamesmanship.\"-- Provided by publisher.
Book
The Decision to Extubate in the Intensive Care Unit
The day of extubation is a critical time during an intensive care unit (ICU) stay. Extubation is usually decided after a weaning readiness test involving spontaneous breathing on a T-piece or low levels of ventilatory assist. Extubation failure occurs in 10 to 20% of patients and is associated with extremely poor outcomes, including high mortality rates of 25 to 50%. There is some evidence that extubation failure can directly worsen patient outcomes independently of underlying illness severity. Understanding the pathophysiology of weaning tests is essential given their central role in extubation decisions, yet few studies have investigated this point. Because extubation failure is relatively uncommon, randomized controlled trials on weaning are underpowered to address this issue. Moreover, most studies evaluated patients at low risk for extubation failure, whose reintubation rates were about 10 to 15%, whereas several studies identified high-risk patients with extubation failure rates exceeding 25 or 30%. Strategies for identifying patients at high risk for extubation failure are essential to improve the management of weaning and extubation. Two preventive measures may prove beneficial, although their exact role needs confirmation: one is noninvasive ventilation after extubation in high-risk or hypercapnic patients, and the other is steroid administration several hours before extubation. These measures might help to prevent postextubation respiratory distress in selected patient subgroups.
Journal Article
Co-existence of congestion and preload-dependence identified by pulse pressure respiratory variations: right ventricular afterload might be the key
[...]other indices have been described to detect right ventricular afterload dependence when using pulse pressure variation such as low baseline tricuspid annular systolic velocity (Sta) and decrease of right ventricular ejection fraction following a fluid challenge [5, 6]. [...]PPV poorly predicts FR in patients with high baseline pulmonary artery pressure [6]. [...]the use of the ratio of early diastolic mitral inflow to average mitral annular tissue velocity (E/e’) to identify high left atrial pressures are limited in the critical care context due to the interactions existing (again) between preload, afterload, diastolic function and mechanical ventilation on the left side of the heart [13]. [...]interpreting separately a high intravascular central venous pressure measured in the superior vena cava may also lead to the false conclusion of venous congestion, in relation with the effect of set and intrinsic PEEP or intra-abdominal pressure on the transmural vena cava pressure. [...]the authors should be congratulated for drawing attention to the complex subject of fluid responsiveness and fluid toxicity in the challenging context of critical care.
Journal Article
Sonographic evaluation of the diaphragm in critically ill patients. Technique and clinical applications
The use of ultrasonography has become increasingly popular in the everyday management of critically ill patients. It has been demonstrated to be a safe and handy bedside tool that allows rapid hemodynamic assessment and visualization of the thoracic, abdominal and major vessels structures. More recently, M-mode ultrasonography has been used in the assessment of diaphragm kinetics. Ultrasounds provide a simple, non-invasive method of quantifying diaphragmatic movement in a variety of normal and pathological conditions. Ultrasonography can assess the characteristics of diaphragmatic movement such as amplitude, force and velocity of contraction, special patterns of motion and changes in diaphragmatic thickness during inspiration. These sonographic diaphragmatic parameters can provide valuable information in the assessment and follow up of patients with diaphragmatic weakness or paralysis, in terms of patient–ventilator interactions during controlled or assisted modalities of mechanical ventilation, and can potentially help to understand post-operative pulmonary dysfunction or weaning failure from mechanical ventilation. This article reviews the technique and the clinical applications of ultrasonography in the evaluation of diaphragmatic function in ICU patients.
Journal Article
Driving Pressure and Survival in the Acute Respiratory Distress Syndrome
This analysis of previously reported trials shows that low tidal volumes, a key component of safer ventilation strategies, confer a protective effect against complications only if the lower volume results in a lower pulmonary driving pressure.
Mechanical-ventilation strategies that use lower end-inspiratory (plateau) airway pressures, lower tidal volumes (V
T
), and higher positive end-expiratory pressures (PEEPs) — collectively termed lung-protective strategies — have been associated with survival benefits in randomized clinical trials involving patients with the acute respiratory distress syndrome (ARDS).
1
–
4
The different components of lung protection in those strategies, such as lower V
T
, lower plateau pressure, and higher PEEP, can all reduce mechanical stresses on the lung, which are thought to induce ventilator-induced lung injury.
5
–
9
Clinical trials, however, have reported conflicting responses to the manipulation of separate components of lung . . .
Journal Article
Potential bias and misclassification of using continuous cardiac output to identify fluid responsiveness compared to calibrated measurements
Discussion and conclusion In this single-center observational study, we identified that 1/ CCO measured immediately before CO recalibration after a FC demonstrated a small negative bias; 2/ ∆%CCO demonstrated intermediate trending capacity with potentially large bias between methods; and 3/ ∆%CCO had acceptable classifying performance to identify fluid responsiveness, with a risk of false negative results. [...]COTPTD measured by triplicate injection demonstrates a precision of ∽7% and least significant change (LSC) of ∽10%, which implies potentially inaccurate adjudication of fluid responsiveness using this technique [5]. [...]using CCO to evaluate fluid responsiveness in patients receiving a FC has the advantage of being efficient, but goes with the risk of misclassification and misleading clinical conclusions.
Journal Article
Esophageal Manometry and Regional Transpulmonary Pressure in Lung Injury
Esophageal manometry is the clinically available method to estimate pleural pressure, thus enabling calculation of transpulmonary pressure (Pl). However, many concerns make it uncertain in which lung region esophageal manometry reflects local Pl.
To determine the accuracy of esophageal pressure (Pes) and in which regions esophageal manometry reflects pleural pressure (Ppl) and Pl; to assess whether lung stress in nondependent regions can be estimated at end-inspiration from Pl.
In lung-injured pigs (n = 6) and human cadavers (n = 3), Pes was measured across a range of positive end-expiratory pressure, together with directly measured Ppl in nondependent and dependent pleural regions. All measurements were obtained with minimal nonstressed volumes in the pleural sensors and esophageal balloons. Expiratory and inspiratory Pl was calculated by subtracting local Ppl or Pes from airway pressure; inspiratory Pl was also estimated by subtracting Ppl (calculated from chest wall and respiratory system elastance) from the airway plateau pressure.
In pigs and human cadavers, expiratory and inspiratory Pl using Pes closely reflected values in dependent to middle lung (adjacent to the esophagus). Inspiratory Pl estimated from elastance ratio reflected the directly measured nondependent values.
These data support the use of esophageal manometry in acute respiratory distress syndrome. Assuming correct calibration, expiratory Pl derived from Pes reflects Pl in dependent to middle lung, where atelectasis usually predominates; inspiratory Pl estimated from elastance ratio may indicate the highest level of lung stress in nondependent \"baby\" lung, where it is vulnerable to ventilator-induced lung injury.
Journal Article
Antibodies against type I interferon: detection and association with severe clinical outcome in COVID‐19 patients
Objectives Impairment of type I interferon (IFN‐I) immunity has been reported in critically ill COVID‐19 patients. This defect can be explained in a subset of patients by the presence of circulating autoantibodies (auto‐Abs) against IFN‐I. We set out to improve the detection and the quantification of IFN‐I auto‐Abs in a cohort of critically ill COVID‐19 patients, in order to better evaluate the prevalence of these Abs as the pandemic progresses, and how they correlate with the clinical course of the disease. Methods The concentration of anti‐IFN‐α2 Abs was determined in the serum of 84 critically ill COVID‐19 patients who were admitted to ICU in Hospices Civils de Lyon, France, using a commercially available kit (Thermo Fisher, Catalog #BMS217). Results A total of 21 of 84 (25%) critically ill COVID‐19 patients had circulating anti‐IFN‐α2 Abs above cut‐off (> 34 ng mL−1). Among them, 15 of 21 had Abs with neutralising activity against IFN‐α2, that is 15 of 84 (18%) critically ill patients. In addition, we noticed an impairment of the IFN‐I response in the majority of patients with neutralising anti‐IFN‐α2 Abs. There was no significant difference in the clinical characteristics or outcome of with or without neutralising anti‐IFN‐α2 auto‐Abs. We detected anti‐IFN‐α2 auto‐Abs in COVID‐19 patients' sera throughout their ICU stay. Finally, we also found auto‐Abs against multiple subtypes of IFN‐I including IFN‐ω. Conclusions We reported that 18% of critically ill COVID‐19 patients were positive for IFN‐I auto‐Abs, whereas all mild COVID‐19 patients were negative, confirming that the presence of these antibodies is associated with a higher risk of developing a critical COVID‐19 form. We report here that 18% of severe COVID‐19 patients were positive for autoantibodies able to neutralize type I interferon (IFN). This finding further confirms the deleterious role of IFN‐I auto‐Abs in the antiviral immune response supporting the use of recombinant type I IFNs not targeted by the auto‐Abs (e.g. IFN‐β) in COVID‐19 patients with an impairment of the IFN‐I response.
Journal Article
Intrathoracic Airway Closure Impacts CO 2 Signal and Delivered Ventilation during Cardiopulmonary Resuscitation
End-tidal CO
(EtCO
) is used to monitor cardiopulmonary resuscitation (CPR), but it can be affected by intrathoracic airway closure. Chest compressions induce oscillations in expired CO
, and this could reflect variable degrees of airway patency.
To understand the impact of airway closure during CPR, and the relationship between the capnogram shape, airway closure, and delivered ventilation.
This study had three parts: 1) a clinical study analyzing capnograms after intubation in patients with out-of-hospital cardiac arrest receiving continuous chest compressions, 2) a bench model, and 3) experiments with human cadavers. For 2 and 3, a constant CO
flow was added in the lung to simulate CO
production. Capnograms similar to clinical recordings were obtained and different ventilator settings tested. EtCO
was compared with alveolar CO
(bench). An airway opening index was used to quantify chest compression-induced expired CO
oscillations in all three clinical and experimental settings.
A total of 89 patients were analyzed (mean age, 69 ± 15 yr; 23% female; 12% of hospital admission survival): capnograms exhibited various degrees of oscillations, quantified by the opening index. CO
value varied considerably across oscillations related to consecutive chest compressions. In bench and cadavers, similar capnograms were reproduced with different degrees of airway closure. Differences in airway patency were associated with huge changes in delivered ventilation. The opening index and delivered ventilation increased with positive end-expiratory pressure, without affecting intrathoracic pressure. Maximal EtCO
recorded between ventilator breaths reflected alveolar CO
(bench).
During chest compressions, intrathoracic airway patency greatly affects the delivered ventilation. The expired CO
signal can reflect CPR effectiveness but is also dependent on airway patency. The maximal EtCO
recorded between consecutive ventilator breaths best reflects alveolar CO
.
Journal Article
Early Corticosteroids in Severe Influenza A/H1N1 Pneumonia and Acute Respiratory Distress Syndrome
Despite their controversial role, corticosteroids are often administered to patients with adult respiratory distress syndrome (ARDS) secondary to viral pneumonia.
To analyze the impact of corticosteroid therapy on outcomes of patients having ARDS associated with influenza A/H1N1 pneumonia.
Patients from the French registry of critically ill patients with influenza A/H1N1v 2009 infection were selected if fulfilling criteria for ARDS, excluding patients having other indication for corticosteroids, or decompensated underlying disease as the primary cause for intensive care unit admission. Survival to hospital discharge was analyzed using Cox regression, accounting for the time to administration of steroids, and after adjustment on the propensity for receiving steroid therapy.
Of 208 patients with ARDS, 83 (39.9%) received corticosteroids (median initial dose of 270 mg equivalent hydrocortisone per day for a median of 11 d). Steroid therapy was associated with death, both in crude analysis (33.7 vs. 16.8%; hazard ratio, 2.4; 95% CI, 1.3-4.3; P = 0.004) and after propensity score-adjusted analysis (adjusted hazard ratio, 2.82; 95% CI, 1.5-5.4; P = 0.002), controlling for an admission severity Simplified Acute Physiology Score, version 3, greater than 50, initial administration of vasopressors, and immunodepression. Early therapy (≤ 3 d of mechanical ventilation) appeared more strongly associated with mortality than late administration. Patients receiving steroids had more acquired pneumonia and a trend to a longer duration of ventilation.
Our study provides no evidence of a beneficial effect of corticosteroids in patients with ARDS secondary to influenza pneumonia, but suggests that very early corticosteroid therapy may be harmful.
Journal Article