Anesthesiology
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Comparative Study
Inspiratory work with and without continuous positive airway pressure in patients with acute respiratory failure.
To compare the effects of continuous positive airway pressure (CPAP) with those of ambient end-expiratory pressure (T-tube) on lung mechanics and blood gas exchange, transpulmonary pressure (Ptp), tidal volume (VT), respiratory frequency, and arterial oxygen and carbon dioxide tensions were measured in 16 spontaneously breathing patients recovering from acute respiratory failure. These variables were measured during breathing through a T-tube; with 18, 12, and 6 cmH2O CPAP; and again during breathing through a T-tube. During all levels of CPAP, mean effective lung compliance (Ceff) was higher and mean total pulmonary power during inspiration lower than during breathing through a T-tube before CPAP (P less than 0.05). ⋯ The authors conclude that CPAP, when adjusted to the appropriate levels, improves lung mechanics in patients recovering from acute respiratory failure. Continuous positive airway pressure reduces total pulmonary power during inspiration and at the same time improves oxygen and carbon dioxide exchange. In these respects, it is preferable to breathing through a T-tube without CPAP.
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The effects on fertility and reproductive wastage of 110 female Swiss/Webster mice and postnatal survival of their offspring were examined after exposure to either air, 0.4% isoflurane, or 0.1% isoflurane. Treatments were for 4 h daily for 2 weeks before and during pregnancy. ⋯ The lack of toxicity of isoflurane is consistent with the results of other reproductive studies in animals that have examined chronic intermittent exposure to subanesthetic concentrations of halothane, enflurane, methoxyflurane, and nitrous oxide. They suggest that these and lower (trace) levels of anesthetic gases may not be the cause of the harmful reproductive effects said to occur in operating room personnel.