The Annals of thoracic surgery
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The etiology and incidence of neurologic injury occurring after cardiac operations employing cardiopulmonary bypass is reviewed. Results of studies demonstrating the role of microemboli generated by pump oxygenators, and evidence for the efficacy of arterial line filtration to decrease delivery of emboli into the cerebral circulation and to decrease postoperative neuropsychological dysfunction, are similarly reviewed. The impact of different strategies for management of pH during moderate hypothermic cardiopulmonary bypass on cerebral blood flow and coupling of cerebral flow and metabolism, as well as their impact on the incidence of postoperative cognitive dysfunction, are also discussed, along with the results of studies examining the efficacy of various agents including thiopental, nimodipine, and nafamostat to decrease cognitive dysfunction subsequent to bypass.
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The primary goal of monitoring cerebral blood flow and metabolism is to improve our understanding of the association with cardiopulmonary bypass and deep hypothermic circulatory arrest so that effective brain protection strategies can be developed and employed. A review of our cerebral blood flow/cardiopulmonary bypass database, presently totaling 275 neonates and infants, for the purposes of this publication, reveals certain trends and some conclusions that can be drawn. Deep hypothermic circulatory arrest continues to be a factor in the delayed recovery of cerebral blood flow and metabolism in these patients. ⋯ We have also examined in our series of 275 patients selective neuroprotection strategies for their potential for improving recovery of cerebral blood flow and cerebral metabolism. Duration of cooling on cardiopulmonary bypass correlates directly with suppression of metabolism due to hypothermia. Low-flow cardiopulmonary bypass instead of deep hypothermic circulatory arrest, and topical brain cooling with ice during deep hypothermic circulatory arrest, improve cerebral blood flow and cerebral metabolic recovery.
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Comparative Study Clinical Trial
Postoperative pain-related morbidity: video-assisted thoracic surgery versus thoracotomy.
One hundred thirty-eight consecutive, nonrandomized patients, with equivalent demographic and preoperative physiologic parameters, underwent either a video-assisted thoracic surgical (VATS) approach (n = 81) or a limited lateral thoracotomy (LLT) approach (n = 57) to accomplish pulmonary resection for peripheral lung lesions (< or = 3 cm in diameter). Wedge resection was done in 74 VATS patients and 19 LLT patients. Seven patients underwent VATS lobectomy and 38 patients had lobectomy performed through an LLT. ⋯ Shoulder girdle strength was equally impaired at day 3, but function was more improved in VATS patients at 3 weeks (p = 0.01). Patients undergoing wedge resection alone by LLT had greater impairment in early (day 3) pulmonary function (forced expiratory volume in 1 second) (p = 0.002); this difference from VATS was not sustained at 3 weeks. Video-assisted thoracic surgery is associated with reduced pain, shoulder dysfunction, and early pulmonary impairment compared with LLT for select patients requiring pulmonary resection.
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Profound hypothermic circulatory arrest and profound hypothermia with continuous low-flow cardiopulmonary bypass are used to facilitate repair of complex congenital heart lesions. Extended periods of profound hypothermic arrest may impair cerebral function and metabolism and produce ischemic brain injury. Low-flow bypass has been advocated as preferable to profound hypothermic arrest with respect to neurologic outcome as it maintains continuous cerebral circulation during repair of heart defects. ⋯ Transcranial Doppler sonography has enabled the noninvasive study of cerebral perfusion during operations using either circulatory arrest or low-flow bypass. Although these studies have demonstrated the presence of cerebral perfusion at low perfusion pressures, evidence exists to suggest that cerebral perfusion abruptly ceases at cerebral perfusion pressures of 7 to 9 mm Hg and is unrelated to pump flow rate. Transcranial Doppler sonography is a useful tool for monitoring cerebral perfusion during low-flow bypass, and future studies with this modality may help to develop improved modes of cerebral protection during repair of complex congenital heart lesions.
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We describe a new noninvasive method using near-infrared spectroscopy for monitoring cerebral hemodynamics during cardiopulmonary bypass in children. All patients were undergoing open heart operations for repair of congenital heart defects. Standardized anesthesia, an alpha-stat method of blood gas management, and nonpulsatile flow were used in all cases. ⋯ During hypothermic bypass (25 degrees C), CBVR was significantly reduced to 0.05 +/- 0.02 mL x 100 g-1 x kPa-1. In addition, there were three values at mean arterial pressure of lower than 40 mm Hg in which CBVR was negative (-0.04 +/- 0.01 mL x 100 g-1 x kPa-1). We conclude that near-infrared spectroscopy is useful for the noninvasive investigation of cerebral hemodynamics during cardiopulmonary bypass.