Chest
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Case Reports
Bilateral ductus arteriosus in d-transposition of the great arteries with right aortic arch.
The rare anomaly of a right aortic arch, distal origin of the left subclavian artery, and posterior left ductus arteriosus (forming a vascular ring) plus a right ductus arteriosus is described in an infant with d-transposition of the great arteries with an intact septum. The presence of a right aortic arch and distal left subclavian artery with bilateral ductus arteriosus has not been described previously.
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A new cannula with a system of intermittent nasal flow was evaluated and compared with a standard constant-flow nasal cannula in 15 patients with chronic obstructive pulmonary disease. The intermittent-demand cannula released oxygen only when a negative pressure was detected in the nose (negative mode) or when a a positive pressure ceased to be detected in the nose (positive mode). At rates of flow varying from 0.63 to 5.60 L/min, the continuous-flow mode used 9 percent more oxygen than the negative mode and 31 percent more oxygen than the positive mode to achieve comparable improvement in arterial oxygen tension. The system using the intermittent-demand cannula was sensitive and reliable in over 150 hours of testing.