Chest
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The inflated cuffed endotracheal tube produces a significant depression of tracheal mucous velocity in anesthetized dogs after one hour. This effect occurs with bot low and high compliance cuffs but is not observed with an uncuffed tube. This phenomenon is another factor that must be considered in establishing criteria for the frequency of cuff deflation in patients supported by mechanical ventilators.
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Blood utilization in 400 consecutive adult patients undergoing a wide variety of cardiovascular operations requiring cardiopulmonary bypass was documented following institution of: 1) complete oxygenator hemodilution; 2) intraoperative phlebotomy and autologous transfusion; 3) infusion of residual oxygenator red cells; and 4) use of reconstituted frozen cells in patients whose blood type was uncommon. These techniques have resulted in an average utilization of 4.8 units of blood per adult patient. Fourteen patients required no blood at all and a total of 259 patients required less than 5 units of blood during their entire hospital course. Physiologic effects of this blood program and hemodilution were evaluated in ten patients and the results indicate that marked reduction of red cell mass by hemodilution with hypothermia and low flow perfusion is not detrimental to satisfactory whole blood oxygenation during open heart surgery.
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Although tracheal tube cuffs are well known to injure the trachea, attempts to design safer cuff systems have been only partially successful. In 14 dogs, we compared three models of high residual volume, low pressure cuffs, which are considered to be among the safest. Two were air-filled cuffs -- a maintained pressure cuff and a balloon reservoir cuff -- and the third was foam-filled. Tracheal dilatation was considerably more severe with mechanical ventilation than with spontaneous breathing, but the foam cuff produced significantly less dilatation (P less than .005) than the air-filled cuffs.