The Journal of thoracic and cardiovascular surgery
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J. Thorac. Cardiovasc. Surg. · Jun 1984
Hemodynamic response to positive end-expiratory pressure following right atrium-pulmonary artery bypass (Fontan procedure).
Thirteen patients were studied in the early postoperative period to determine the hemodynamic response to increasing levels of positive end-expiratory pressure (PEEP) following right atrium-pulmonary artery bypass (Fontan procedure). Hemodynamic data and arterial oxygen and carbon dioxide tensions were measured without PEEP and with PEEP = 3, 6, 9, and 12 cm H2O. Cardiac index decreased progressively with increasing levels of PEEP compared to PEEP = 0 (cardiac index = 2.7 +/- 1.2 L/min/m2), and the decrease was significant at PEEP = 9 (cardiac index = 2.2 +/- 0.8 L/min/m2, p less than 0.05) and 12 cm H2O (cardiac index = 2.0 +/- 0.7 L/min/m2, p less than 0.05). ⋯ From these data it appears that PEEP is an effective means of raising arterial oxygen tension after right atrium-pulmonary artery bypass. A progressive fall in cardiac index occurs with increasing PEEP, and the fall becomes significant at PEEP greater than 6 cm H2O. The fall in cardiac index appears to be mediated by a significant rise in pulmonary vascular resistance index.
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J. Thorac. Cardiovasc. Surg. · May 1984
Blood flow distribution in infant pigs subjected to surface cooling, deep hypothermia, and circulatory arrest. Deleterious effects in pigs with left-to-right shunts.
Surface cooling, deep hypothermia and circulatory arrest have been used effectively for correction of congenital heart defects in infancy. Which patients are best suited for this technique has not been addressed. The addition of surface cooling to deep hypothermia and circulatory arrest provides homogeneous cooling and avoids swelling due to reperfusion injury after circulatory arrest. ⋯ The distribution of cardiac output in Group I did not change with surface cooling; however, Group II pigs showed marked change in distribution of cardiac output, resulting in decreased renal, visceral, and pulmonary flow (p less than 0.05). Amylase determinations before and after surface cooling, deep hypothermia, and circulatory arrest were unchanged in Group I but elevated in Group II (p less than 0.05). These observations suggest altered cellular metabolism in visceral organs during the period of surface cooling which may be compounded by circulatory arrest and rewarming.
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J. Thorac. Cardiovasc. Surg. · May 1984
Relationship of brain blood flow and oxygen consumption to perfusion flow rate during profoundly hypothermic cardiopulmonary bypass. An experimental study.
A study was made of the relation of brain blood flow and oxygen consumption to changes in perfusion flow rate during cardiopulmonary bypass at 20 degrees C in nine cynomolgus monkeys. Four perfusion flow rates varying from 0.25 to 1.75 L X min-1 X m-2 were randomly instituted, each for a 10 minute period. At the end of each period, brain arteriovenous oxygen content difference was measured and 15 mu radioactive microspheres were injected into the arterial perfusion line. ⋯ There was a greater reduction of blood flow in the cortical white matter (p = 0.01) than in other regions of the brain. Brain oxygen consumption was the same (p = 0.5) at all perfusion flow rates, related to an increasing percent oxygen extraction with decreasing perfusion flow rate (p less than 0.0001). The data indicate that all areas of the brain remain perfused, even at low perfusion flow rates, during profoundly hypothermic cardiopulmonary bypass, and that brain oxygen consumption is maintained in part by increased oxygen extraction and in part by redistribution of the perfusate from the remaining body to the brain.
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J. Thorac. Cardiovasc. Surg. · May 1984
Surgical palliation of subaortic stenosis in the univentricular heart.
Seventeen patients with a univentricular atrioventricular connection and subaortic stenosis at the outlet foramen level were seen from 1974 until 1983. The ventricular anatomy was of a single left ventricle with an outlet chamber, and the great arteries were transposed. This condition often followed pulmonary artery banding (15 cases) but also occurred with pulmonic stenosis (one) or pulmonary atresia (one). ⋯ Thirteen patients had a resting gradient to 118 mm Hg and three a gradient only with isoprenaline infusion. The following surgical procedures have been performed: (1) insertion of a conduit between the left ventricle and aorta (one patient); (2) creation of an aorticopulmonary window proximal to the band and tightening of the band (three patients); (3) enlargement of the ventricular septal defect (three patients); (4) Fontan procedure (five patients); and (5) Fontan procedure plus arterial switch (two patients). All of the procedures but the last one have met with significant mortality in this difficult group of patients.
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Information on the role of the intensivist in postoperative cardiovascular patient care was obtained from a national survey of cardiac surgeons. The cardiac surgeon today retains overall responsibility for patient care. ⋯ Intensivists are less likely to practice in nonteaching hospitals and less likely to be present in those cardiac surgical units that are not combined with other services. Because of the preponderance of intensivists in training programs, the surgical resident's role in patient care may be reduced in the future.