Seminars in cardiothoracic and vascular anesthesia
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Therapeutic hypothermia, introduced more than 5 decades ago, remains an important neuroprotective factor in the surgery for the correction of congenital heart disease, in particular when intraoperative circulatory arrest is required. Hypothermia decreases cerebral metabolism and energy consumption and reduces the extent of degenerative processes such as the excitotoxic cascade, apoptotic and necrotic cell death, microglial activation, oxidative stress, and inflammation. Neurological outcome has become the focus of several studies in the recent years, and deep hypothermic circulatory arrest durations of more than 40 minutes are associated with increased mid- and long-term disability. ⋯ Although evidence from animal studies suggests potential benefit from very low temperatures, postoperative development of choreoathetosis has been found to correlate with the degree of intraoperative hypothermia, recommending the use of central temperatures greater than 15 degrees C in the clinical practice. Cooling times longer than 20 minutes are needed to obtain homogeneous brain cooling and effective neuroprotection. Finally, there is evidence that the sites of temperature monitoring used in the clinical practice may underestimate brain temperature after cardiopulmonary bypass, with the risk of postoperative hyperthermic brain damage.
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Brain protection during cardiopulmonary bypass has been the subject of intense research. Deep hypothermic circulatory arrest (DHCA) continues to be used for that goal during complex aortic arch and large intracranial aneurysm surgeries. ⋯ Based on our experience and review of the current literature, the authors highlight the key areas of the anesthetic plan, discussing the risk factors associated with adverse neurologic outcome as well as the rationale for decisions regarding specific monitors and medications. In the conclusion an anesthetic protocol for adult patients undergoing DHCA is suggested.
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Semin Cardiothorac Vasc Anesth · Mar 2007
ReviewBleeding following deep hypothermia and circulatory arrest in children.
Deep hypothermic circulatory arrest (DHCA) is a technique of extracorporeal circulation commonly used in children with complex congenital heart defects undergoing surgical repairs. The use of profound cooling (20 degrees C) and complete cessation of circulation allow adequate exposure and correction of these complex lesions, with enhanced cerebral protection. ⋯ This review examines the impact of DHCA on bleeding and transfusion requirements in children and the pathophysiology of DHCA-induced platelet dysfunction. It also focuses on possible pharmacologic interventions to decrease bleeding following DHCA in children.
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Semin Cardiothorac Vasc Anesth · Mar 2007
ReviewSurrogate markers for neurological outcome in children after deep hypothermic circulatory arrest.
Improved survival for infants with congenital heart disease (CHD) has led to increased focus on the most significant morbidities that are neurodevelopmental. Neurologic injury in neurodevelopmental outcome may have many causes in children with complex CHD undergoing cardiopulmonary bypass and deep hypothermic circulatory arrest, including genetic syndromes, abnormal blood flow patterns, prenatal insults, and hemodynamic instability. Although gross neurological injury can be detected in the perinatal and postoperative period, more subtle injury may not be identified until much later. ⋯ Serologic proteins, seizures, magnetic resonance findings, cerebral oxygenation, and the neurologic examination have all been studied. Continuing innovation in the use of magnetic resonance imaging techniques and the application of physiologic measures including near-infrared spectroscopy currently pose the greatest potential for advances. This article summarizes the state of the art and an admission about how far we have yet to travel as we strive to make the neurodevelopmental outcomes of patients with CHD comparable to their healthy peers.
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Semin Cardiothorac Vasc Anesth · Dec 2006
ReviewInhaled milrinone: a new alternative in cardiac surgery?
The administration of milrinone through inhalation has been studied in only a few animal and human studies. Compared to the intravenous administration, inhaled milrinone has been shown to reduce pulmonary artery pressure without systemic hypotension. Therefore, this approach could represent an alternative to nitric oxide. This current state of knowledge of intravenous and inhaled milrinone is presented and summarized.