Current opinion in anaesthesiology
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Curr Opin Anaesthesiol · Jun 2002
Upper airway infection and pediatric anesthesia: how is the evidence based?
Anesthesia for the child with an upper respiratory infection remains one of the most common, yet contentious, issues facing the pediatric anesthesiologist. A general lack of evidence-based research has led to disparities in the manner in which children with upper respiratory infections have been traditionally managed. More recent research, however, suggests that children with uncomplicated infections can be managed safely, given that most complications can be anticipated, recognized, and treated. This review summarizes the evolving literature regarding cancellation of surgery for the child with an upper respiratory infection, perioperative outcomes, and anesthetic management.
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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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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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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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'Suspended animation for delayed resuscitation' is a new concept for attempting resuscitation from cardiac arrest of patients who currently (totally or temporarily) cannot be resuscitated, such as traumatic exsanguination cardiac arrest. Suspended animation means preservation of the viability of brain and organism during cardiac arrest, until restoration of stable spontaneous circulation or prolonged artificial circulation is possible. Suspended animation for exsanguination cardiac arrest of trauma victims would have to be induced within the critical first 5 min after the start of cardiac arrest no-flow, to buy time for transport and resuscitative surgery (hemostasis) performed during no-flow. ⋯ In the 1990s, the Pittsburgh group achieved survival without brain damage in dogs after cardiac arrest of up to 90 min no-flow at brain (tympanic) temperature of 10 degrees C, with functionally and histologically normal brains. These studies used emergency cardiopulmonary bypass with heat exchanger or a single hypothermic saline flush into the aorta, which proved superior to pharmacologic strategies. For the large number of normovolemic sudden cardiac death victims, which currently cannot be resuscitated, more research in large animals is needed.