Phytothérapie de la dépression

Editorial

Le changement     

Lésions d’ischémie-reperfusion rénale

Ischemia-reperfusion-induced renal injury due to profound decrease of renal blood flow followed by restoration of renal perfusion is frequent in critically ill patients. Ischemic-induced microcirculatory dysfunction and perfusion defects persist after reperfusion leading to extension of initial renal damage, renal fibrosis, and acute or chronic renal failure. Renal ischemia-reperfusion should not be regarded as a sole ischemic injury with acute tubular necrosis but involves renal inflammation with infiltration of immune cells with tubular necrosis and apoptosis. Despite numerous promising pre-clinical therapeutic interventions protecting the kidney from ischemic injury, such strategies have been mostly unsuccessful in the clinical setting. Multiplicity of factors involved with complexes mechanisms of injury in most clinical scenarios may explain such discrepancy.     

Réveil peropératoire et mémorisation au décours d’une césarienne sous anesthésie générale

Awareness with recall in association with general anaesthesia for caesarean section occurs more frequently than in other operations (0.1–0.2%). The 5th National Audit Project (NAP5) of the Royal College of Anaesthetists and the Association of Anaesthetists of Great Britain and Ireland identified many risk factors for awareness. These included: physiological changes during pregnancy such as higher cardiac output resulting in a wider distribution of drugs and thus lower blood levels of induction agents and volatile anaesthetics, omission of, or decrease in the dose of some drugs to minimize their effects on uterine tone and to avoid fetal exposure, a brief period between anaesthetic induction and start of surgery with little time for reinforcement of the intravenous in duction dose with a volatile agent, use of neuromuscular blocking drugs, difficult airway management, obesity and a high incidence of urgent/immediate surgery often performed out of hours, resulting in higher rates of nonconsultant care. The period from the start of induction of anaesthesia to the start of the surgical intervention, including induction of anaesthesia, is the time when awareness most commonly occurred. Such awareness with recall may cause severe postoperative psychological sequelae, including posttraumatic stress disorder, anxiety, neurosis, nightmares, fear of hospitals. Assessing depth of anesthesia remains a challenge for the anesthesia provider as clinical signs are unreliable, induction drugs vary in their ability to produce amnesia and the period of hypnotic effect is affected by the rate at which they are redistributed. After initiation of anesthesia, volatile anesthetics should be administered to a target of 0.7 minimum alveolar anesthetic concentration, which has been shown to consistently achieve mean Bispectral Index scores <60. Routine brain function monitoring of patients undergoing caesarean section under general anaesthesia does not guarantee unconsciousness as lower Bispectral Index goal of scores seems to be necessary in this population.     

Comprendre le deuil pour mieux accompagner les proches de patients décédés en réanimation

Intensive care unit (ICU) caregivers are regularly confronted with end-of-life and care for the patients’ relatives who will soon be bereaved persons. Bereavement is not a problem nor a pathology: it is a painful and intense period during which the bereaved person adjusts to living without his/her loved-one, while resuming his/her “normal” course of life. However, grieving can sometimes become a more complex process requiring professional help. This text is designed to understand individual grief and its social implications, its course and its mechanisms, but also its potential complications: the knowledge of this process will enable caregivers to understand the bereaved relatives of ICU patients and to attempt to prevent grieving complications associated with the ICU context and the dying and death process.     

Thérapeutiques dˈexception au cours des défaillances circulatoires et respiratoires dˈorigine toxique

Circulatory assist devices have rarely been used in poisonings. Their efficacy has been demonstrated in five animal studies of intoxication by cardiotropic drugs or tricyclic antidepressants. Twenty-five cases of human poisonings by antiarrhythmic drugs or other cardiotoxic products and treated by circulatory support (ECMO or IABP) have been reported. The use of circulatory assist devices allowed the recovery in 80% of those patients who presented shock (seven times) or cardiac arrest (18 times) refractory to maximal therapy. Although the indications are rare, these techniques may be life-saving if the medical and technical conditions are fulfilled. Respiratory support by ECMO has been used in some cases of acute respiratory distress syndrome due to hydrocarbons but their usefulness has not been demonstrated.     

Le décubitus ventral dans le syndrome de détresse respiratoire aiguë

It is now well established that prone position (PP) sessions can improve arterial oxygenation in the majority of patients with acute hypoxemic respiratory failure. The underlying mechanism of this beneficial response is not completely understood but is likely due to the alveolar recruitment of the dependent lung units which are atelectatic in supine position and remain still perfused in prone position. Some animal studies suggest that PP could reduce the extent of lung damage resulting from high tidal volumes applied during mechanical ventilation, and can increase the efficiency of recruitment manoeuvres, like sustained inflation, at lower levels of positive-end expiratory pressure. Optimal prone positioning is relatively easy to perform without any specific additional equipment. It requires, however, trained and motivated medical and nursing staff and an available written procedure. The impressive complications observed in the early days, such as endotracheal tube or central venous lines removal while changing positions, no longer occur. The overpressure-induced skin lesions can be significantly reduced by following precise recommendations. Some questions are still not resolved in the clinical practice, such as: when should PP be started from the onset of mechanical ventilation? Probably as early as possible. What should be the optimal duration of the PP session? For how long should we continue PP in a responder patient? One important issue, namely the impact of PP on patient outcome, is being tested in randomized control trials, which are ongoing in three European countries.     

Cathéters d’épuration extra-rénale aiguë

Acute catheters for renal replacement therapy (RRT) are used for immediate vascular access in ICU patients with acute renal failure. Most acute catheters are made of poly-urethane, but silicone catheters are also available. The primary determinants of catheter blood flow are the diameter of the catheter and its tip placement. The subclavian insertion site should not be used in a patient who may need permanent vascular access. Femoral catheters seem to be associated with a higher risk of bacteremia than internal jugular catheters. Femoral placement demands a longer length catheter (≥20 cm) for a regular blood flow with limited recirculation. In general, catheter blood flow problems that occur early after placement are related to catheter position while those that occur late are related to thrombosis. Following its use, proper flushing and anticoagulation of the catheter with concentrated heparin or citrate will serve to decrease the risk of internal thrombosis.     

CIVD et défaillance d’organes : arguments expérimentaux et cliniques

Disseminated intravascular coagulation (DIC) is thought to contribute to multiple organ failure in a variety of underlying conditions for several reasons. First, clinical studies have found that, in patients with severe sepsis or septic shock, those with DIC exhibited more acquired organ failures than those without DIC, and their mortality rate was higher. Second, experimental studies of DIC associated with sepsis or low-grade activation of coagulation have repeatedly indicated that effective inhibition of DIC can indeed reduce organ failures and mortality. The mechanisms by which this role could be effectuated, however, are not clearly understood. The repeatedly demonstrated microvascular fibrin deposition in tissues of patients who have died from an illness with evidence of DIC may deprive downstream cells of oxygen, and cellular hypoxia could be a mechanism by which cells are damaged. In contrast, many investigators currently believe that it is not fibrin formation itself that is harmful, but rather is the generation of serine proteases and their interactions with pro-inflammatory mediators that contributes to organ failure and death. With the emergence of powerful anticoagulant strategies, aspects involving ischemia-reperfusion damage and organ recovery become important to investigate.     

Décision d’extubation programmée en réanimation

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 the 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 the 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.     

Modèle animaux d’obésité

Animal models provide major contribution to our understanding of the physiological, environmental, genetic and epigenetic bases of obesity. Most rodent models of obesity have been investigated since the early fifties, but it??s only more recently that the mechanisms underlying their phenotype were identified, thanks to the development of molecular biology. This article reviews various models of rodent obesity, naturally occurring or created by researchers: nutritional obesity induced by a high fat diet, hypothalamic obesity resulting from lesions in areas controlling food intake and genetic obesity due to spontaneous mutations in crucial genes for energy balance, such as leptin and leptin receptor genes. Each model provides information related to specific aspects of human obesity, particularly in the field of monogenic obesities that are rare but often severe as in leptin-deficient patients. Models of obese rodents represent precious and necessary tools to explore the complexity of energy balance regulation and for innovative therapeutic intervention in obesity, of which the success of leptin treatment for leptin-deficient patients is a striking example.