Chest
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After operative coronary revascularization, 14 consenting adults received conventional positive pressure ventilation (PPV). When they were hemodynamically stable, data were collected during PPV and then during airway pressure release ventilation (APRV). During APRV, airway pressure (Paw) was reduced periodically at the lowest frequency which produced normal PaCO2. ⋯ All patients were weaned from APRV without complication. Optimal ventilator design for patients with acute lung injury would provide CPAP as a primary intervention and secondarily would augment alveolar ventilation. The APRV supported oxygenation and ventilation in patients with mild acute lung injury, yet with much lower peak airway pressure than produced by PPV.
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Thirty-one patients with severe respiratory failure who were failing volume controlled conventional ratio ventilation were placed on pressure controlled inverse ratio ventilation (PC-IRV) for a total of 4,426 patient-hours. The PC-IRV resulted in a reduction of minute ventilation from 22 +/- 1.0 L/min (mean +/- SEM) to 15 +/- 0.7 L/min. Peak inspiratory pressure (PIP) was reduced from 66 +/- 2.3 cm H2O to 46 +/- 1.6 cm H2O and positive end expiratory pressures (PEEP) from 15 +/- 1.0 cm H2O to 2.5 +/- 0.5 cm H2O. ⋯ A lung compromise index (FIO2. PIP.10/PaO2) retrospectively distinguished between successful and unsuccessful PC-IRV episodes. These data suggest that PC-IRV can be successfully and safely implemented in critically ill patients with severe respiratory failure over prolonged periods of time resulting in significant improvement in oxygenation at lower minute volume, peak airway pressure and PEEP requirements.
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We measured the flow-resistance of five commercially available 10 cm H2O expiratory positive-pressure (EPP) valves (n = five per valve type) at bias flows of between 0 and 2,000 ml/s. We found that individual valves of each type and manufacturer functioned similarly. ⋯ We conclude that system pressure is not similar in all continuous positive airway pressure (CPAP) systems using bias flow and EPP valves. The work of breathing imposed by CPAP circuits will be increased in systems whose EPP valves have flow-dependent properties.
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Case Reports
Ten-year experience with extracorporeal membrane oxygenation for severe respiratory failure.
In the last ten years, 17 patients with respiratory failure refractory to standard ventilator therapy have been treated with extracorporeal membrane oxygenation (ECMO) at the Toronto General Hospital. One patient was treated with ECMO twice. Four perfusions were veno-arterial, the remainder veno-venous. ⋯ Multiple surgical procedures have been performed successfully during use of ECMO including lung lavage, open lung biopsy and three lung transplants. Major complications include hemorrhagic diatheses and sepsis. The technique involves a substantial commitment of time and personnel but remains a tenable option for presumed reversible life-threatening respiratory failure.
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Tracheobronchopathia osteochondroplastica (TO) is a rarely described disorder which historically has not been frequently recognized antemortem. Studies by computerized tomography (CT) and bronchoscopy now permit a definitive antemortem diagnosis and can obviate a more invasive diagnostic evaluation. We describe two cases of TO presenting as right middle lobe collapse, discuss the clinical and pathologic features, and outline an approach to its evaluation using CT and bronchoscopic study.