Current opinion in anaesthesiology
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Current reviews and consensus documents now recommend a more discriminating approach to the traditional practices of delivering liberal infusions of intravenous fluid to all major trauma patients with suspected or known major hemorrhage. The evolving evidence suggests that aggressive fluid resuscitation prior to hemostasis leads to additional bleeding through hydraulic acceleration of hemorrhage, soft clot dissolution, and dilution of clotting factors. ⋯ Although most clinicians still generally support fluid resuscitation for multisystem blunt trauma, particularly with head injury, the most recent experimental data have begun to challenge this traditional practice as well, suggesting a 'slow infusion' approach when there is risk for uncontrolled internal bleeding. By providing oxygen delivery with slow, limited infusion, new hemoglobin-based oxygen carriers might help to resolve the current dilemma of having to limit preoperative resuscitation when there is risk of uncontrolled hemorrhage.
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The goal of mechanical ventilation in patients with acute lung injury is to support gas exchange and mitigate ventilator-associated lung injury. High-frequency oscillatory ventilation relies on the generation of a constant distending pressure, small tidal volumes and rapid respiratory rates with the intent to recruit atelectatic lung, reduce peak inflating pressures and limit volutrauma. The utilization of high-frequency oscillatory ventilation has dramatically increased in neonatal and pediatric intensive care units. ⋯ High-frequency oscillatory ventilation has been used successfully to manage patients with severe respiratory failure who have failed conventional mechanical ventilation. When initiated early, high-frequency oscillatory ventilation has been shown to improve oxygenation and reduce acute and chronic lung injury in neonates, infants and children. Further trials are necessary to better delineate the benefits and risks of this therapy in various patient populations.
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Cervical spine injuries occur in 2-5% of blunt trauma patients, and 1-5% of these injuries are initially missed. Data from the large National Emergency X-Radiography Utilisation Study have helped to define the problem in some detail. There is a consensus on how to clear the cervical spine in patients who are alert, but in patients with altered mental status the choice of strategy for spinal clearance is more controversial. ⋯ As long as manual in-line neck stabilization is applied, rapid sequence induction of anaesthesia, followed by direct laryngoscopy and oral intubation appears to be safe in the patient with a cervical spine injury. If intubation is not urgent, an awake fibreoptic technique is a useful option. If intubation of the patient with a potential cervical spine injury fails, or appropriate experienced personnel are unavailable, the laryngeal mask airway or one of its various modifications are useful alternatives.
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In the last few years, video assisted thoracoscopy, which allows a wide variety of diagnostic and therapeutic procedures, has been introduced into clinical practice. A growing enthusiasm for minimally invasive surgical approaches and improvements in video endoscopic surgical equipment has resulted in the widespread use of this technique. Most video assisted thoracoscopy procedures require a well-collapsed lung and should only be included in the absolute indication for one-lung ventilation. ⋯ Finally, there are alternatives to the use of the double-lumen tube to achieve lung separation, such as the Univent tube or an independent bronchial blocker. In many situations the double-lumen tube cannot be inserted, due to a difficult airway or at the conclusion of the procedure changing the double lumen tube to a single lumen tube may result in loss of control over the airway. In such situations, it is essential for the anesthesiologists to be familiar with the existing alternatives to the double-lumen tube.
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Mechanical ventilation is a life-supporting process employed in the management of respiratory failure. Over the years, our understanding of the pathophysiology of lung injury has greatly improved, and has aided the technological development of ventilatory modes that are more patient 'sensitive' and less traumatizing to the lungs. This review will discuss the fundamental modes of mechanical ventilation, and present current concepts regarding patient-ventilator interaction that either promote lung healing and weaning from positive pressure ventilation or delay recovery because of the injudicious use of ventilatory modalities that are incapable of meeting the ventilatory demands of the patient on a breath-by-breath basis. In addition, the current strategy for mechanical ventilation in acute lung injury and acute respiratory distress syndrome will be summarized.