The Annals of thoracic surgery
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The effects of oxygen and 60% nitrous oxide and oxygen on the pressure and volume of Portex low-pressure (LP) and high-pressure (HP) endotracheal tube cuffs were determined in 120 intubated patients undergoing thoracic surgical procedures. Cuffs were filled with either room air or a sample of the inspired gases. ⋯ Cuff gas analysis revealed that cuff volume changes were due to diffusion of oxygen and nitrous oxide into the cuff and failure of nitrogen to diffuse out. These findings suggest that cuff overexpansion during anesthesia or prolonged ventilation may be an important cause of tracheal trauma.
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Pulmonary mechanics and oxygenation were measured in 24 consecutive patients with posttraumatic flail chest requiring continuous mechanical ventilation. The mean duration of mechanical ventilation was fourteen days. Mortality was 38% for all patients, 29% if deaths from head injury are excluded. ⋯ Vital capacity and maximal inspiratory force measurements were useful in assessing chest wall stabilization. Total lung compliance correlated negatively with fatal outcome from respiratory failure. The alveolar-arterial oxygen gradient was not useful in assessing chest wall stabilization.
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Applying subdiaphragmatic compression has been successful in saving victims of food-choking and drowning by expelling the asphyxiating bolus or aspirated water. Sudden elevation of the diaphragm compresses the lungs, which explosively forces air out through the trachea, ejecting the obstructing object. The flow rate, pressure, and volume of air expelled were determined in 10 subjects and found to be substantial, providing confirmation of the effectiveness of the procedure.
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Activated clotting time (ACT) was used in 300 consecutive patients undergoing cardiac operations to determine the adequacy of heparin reversal. Mean ACT prior to protamine sulfate administration was 9 minutes 40 seconds. ⋯ Normal values for ACT usually coincided with clotting in the operative field. ACT proved to be a reliable guide to protamine sulfate administration.
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Comparative Study
Management of flail chest without mechanical ventilation.
The pathophysiology of flail chest is usually described only on the basis of paradoxical respiration, ignoring underlying pulmonary contusion. Two groups of comparable patients were treated either with early tracheal intubation and mechanical ventilation (Group 1), or with fluid restriction, diuretics, methylpredinisolone, albumin, vigorous pulmonary toilet, and intercostal nerve blocks, ignoring the paradox and treating only the underlying lung (Group 2). When tracheostomy and mechanical ventilation were not used the mortality rate went from 21% to O(p = 0.01), the complication rate from 100% to 20% (p = 0.005), and the average hospitalization from 31.3 to 9.3 days (p = 0.005). We conclude that most patients with flail chest do not need internal pneumatic stabilization if the underlying lung is treated appropriately and that tracheostomy and prolonged mechanical ventilation with a volume respirator, as practiced in most respiratory care centers, is usually a triumph of technique over judgment.