Chest
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We compared 11 patients with upper airway obstruction (obstruction at or proximal to the carina) to 22 patients with chronic obstructive pulmonary disease and to 15 normal subjects utilizing spirometry, lung volumes, airway resistance, maximal voluntary ventilation, single-breath diffusion capacity, and maximal inspiratory and expiratory flow-volume loops. Four values usually distinguished patients with upper airway obstruction: (1) forced inspiratory flow at 50 percent of the vital capacity (FIF50%) less than or equal to 100 L/min; (2) ratio of forced expiratory flow at 50 percent of the vital capacity of the FIR50% (FEF50%/FIF50%) larger than or equal to 1; (3) ratio of the forced expiratory volume in one second measured in milliliters to the peak expiratory flow rate in liters per minute (FEV1/PEFR) larger than or equal to 10 ml/L/min; and (4) ratio of the forced expired volume in one second to the forced expired volume in 0.5 second (FEV1/FEV0.5) larger than or equal to 1.5. The last ratio can be determined with a simple spirometer.
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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.