Administration d’aérosols médicamenteux au cours de la ventilation mécanique

Mechanical ventilation was historically considered as a barrier to administer inhaled aerosolized drugs. Nowadays, inhaled aerosolized drug administration during mechanical ventilation is quite relevant, thanks to the understanding of the key factors ruling the complex interaction between the aerosol and mechanical ventilation. Availability of beta-2-mimetics and corticosteroids as metered-dose inhalers makes their delivery simple when using inhalation chambers dedicated to mechanical ventilation. Administration of other molecules like antibiotics requires the use of a nebulizer. The choice between pneumatic, ultra-sonic, and mesh nebulizers will be discussed. Several means allow optimizing nebulization performance, including the placement of continuous nebulizer 15?C40 cm before the Y piece, the reduction in inspiratory flow, and the use of inspiration-synchronized nebulizers. When performed during mechanical ventilation, they led to significant clinical results. Here, experimental and clinical data regarding beta-2-agonists, corticosteroids, and antibiotics efficiency when delivered as inhaled aerosols during mechanical ventilation, will be high-lightened. Consistently, inhaled treatment of ventilator associated pneumonia appears promising. Finally, recommendations for implementation of aerosol therapy during mechanical ventilation will be presented for the clinical practice.     

Nébulisation de médicaments sous ventilation mécanique

Nebulizing drugs is possible with small-volume nebulizers or metered-dose inhalers. Both required specific adaptations to be used during mechanical ventilation. Ventilator patterns have also to be adjusted to optimize the inhaled mass of drug. The best evidence favors the use of bronchodilatator agents in COPD or asthmatic patients. More clinical studies are needed to determine indications for using antiinfectious.     

Évaluation du pouvoir antimicrobien des huiles essentielles de sept plantes médicinales récoltées au Maroc

This study consist to evaluate the antimicrobial effectiveness of certain medicinal plants (Majorana hortensis, Myrtus communis, Mentha rotundifolia, Pelargonium graveolens, Salvia officinalis, Lavandula stoechas, Lavandula angustifolia) judged by the Moroccan traditional medicine have great anti-infective effect. In order to rationalize their use to apply as an alternative to antibiotics cure with the emergence of bacterial multidrug resistance and failure of antibiotic therapy.The essential oils of these plants were tested on seven pathogenic multidrug resistant microbial strains: five bacterial strains Gram (-) (Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Proteus rettgeri, Pseudomonas aeruginosa) one Gram (+) bacteria (Staphylococcus aureus); and Candida albicans as yeast.Very interesting antimicrobial properties of essential oils studied have been noted against the majority of tested germs. This antimicrobial activity on yeast and Gram (+) and Gram (-) multidrug-resistant bacteria, may contribute to fight against infectious diseases and eventually offer the possibility of using pomegranate leaves in food or pharmaceutical industry.     

Utilisation des filtres échangeurs de chaleur et d’humidité au cours de la ventilation mécanique des patients de réanimation

Adequate heating and humidifying of inspired gases is required for long-term mechanical ventilation of intensive care unit (ICU) patients. This process can be achieved by either a heated humidifier or by more recent disposable devices called heat and moisture exchangers (HME). The choice to use one method instead of the other depends on both technical and economic considerations. HMEs are more often used nowadays because they are simple to use and cost-effective. Their performances are for several models comparable to those of a heated humidifier. The vast majority of ICU patients can be ventilated with an HME. They are usually changed after 24 h of use. It has recently been shown that some HMEs can be changed only every 48 h and that at least one HME can be changed only once a week in some patients. Using HMEs instead of heated humidifiers has no clear impact on the rate of nosocomial pneumonia but considerably reduces the cost of mechanical ventilation and the number of septic procedures, thus improving quality of care.     

L'insuffisance respiratoire aiguë du syndrome de Guillain-Barré et de la myasthénie auto-immune. De la détection au sevrage de la ventilation mécanique

Guillain-Barré syndrome (GBS) and myasthenia gravis (MG) are the most common neuromuscular causes of acute respiratory failure. Their prognosis has been considerably improved by the advent of mechanical ventilation. However patients remain at risk of respiratory arrest, because the severity of respiratory failure is often underestimated as patients often have minimal symptoms. Aspiration pneumonia, nonspecific complications of mechanical ventilation and weaning failure may also occur. Respiratory failure may be due to weakness of inspiratory and/or expiratory muscles, which can be assessed by the measurement of vital capacity (VC) and static maximal pressures. Bulbar dysfunction may also be a contributory factor. Patients with respiratory symptoms, especially orthopnoea, a reduction of VC below 60% of the predicted value or bulbar weakness must be referred to intensive care, particularly since GBS follows a progressive course and MG is characterized by fluctuating motor deficit. Criteria for mechanical ventilation include signs of respiratory distress, hypoxemia, hypercapnia or a VC below 20% predicted, but because of the risk of aspiration, major bulbar weakness can also be considered to be an indication. Weaning should only be started if there has been neurological improvement and VC is above 20%. Extubation should be preceded by a prolonged trial of spontaneous ventilation. Measurement of VC is essential at each step of the evolution of neuromuscular respiratory failure.     

Les mécanismes de la conscience

Understanding mechanisms of consciousness is a neuroscientific challenge with potential important medical applications. Mechanisms of conscious state should be distinguished from those of conscious access. Regarding conscious state, arousal is a necessary condition for consciousness but it is not a sufficient one. A network of frontal and parietal heteromodal associative areas is also implicated in the emergence of awareness. The same network is necessary for conscious access to given information by the subject as well. Our understanding of consciousness mechanisms allows us to identify, prognosticate and stimulate reappearance of consciousness in a non-conscious patient.     

Intoxication au monoxyde de carbone et place de l’oxygénothérapie hyperbare

Hyperbaric oxygen (HBO) is used since more than 50 years for carbon monoxide poisoning. However, HBO protocols and indications are still debated. Neurological (coma and delayed neuropsychological sequelae) and cardiac (ischemic changes with normal coronary arteries) clinical scenarios are explained by complex mechanisms. Carboxyhemoglobin formation, cytochrome oxydase inhibition, oxidative stress, as well as ischemia-reperfusion phenomenon are among these mechanisms. Venous and arterial carboxyhemoglobin levels are not correlated with the patient’s final prognosis and thus not mandatory for indicating the treatment. Conversely, troponin IC measurement is strongly recommended if myocardial involvement is suspected. HBO treatment relies on mechanistic bases: earlier detoxification, anti-oxidant properties, and improvement in cerebral physiology (decrease in intracranial pressure and oedema, and ischemic penumbra preservation). Clinical basis is assessed by the results of the randomized clinical trials (RCTs). Four among the 5 RCTs using > 2 ATA OHB protocols were positive. Two RCTs at 2 ATA level were negative. Therefore, international guidelines recommend OHB with at least 2.5 ATA in patients at risk of delayed neuropsychological sequelae, whatever the objective neurological signs are, in pregnant women, and patients with myocardial involvement. If OHB is not required, normobaric oxygen with high flow rates during at least 8-12 hours is mandatory.