Chest
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Earlier reports of a two wavelength oximeter suggested a tendency toward overestimation of arterial oxygen saturation (SaO2) at the lowest values examined. To investigate this possible inaccuracy, we compared oximeter readings to SaO2 over a wider range of laboratory-induced steady-state hypoxia than has previously been reported. ⋯ However, when SaO2 was less than 75 percent, the instrument readings were progressively higher than the SaO2 so that when SaO2 was approximately 50 percent, the oximeter reading was approximately 65 percent. These data show that the two wavelength oximeter displays falsely elevated readings when the arterial saturation falls below 75 percent.
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Comparative Study
Continuous positive airway pressure and expiratory positive airway pressure increase functional residual capacity equivalently.
The effect of continuous positive airway pressure (CPAP) and expiratory positive airway pressure (EPAP) on functional residual capacity (FRC) of ten healthy, spontaneously breathing, lightly anesthetized intubated mongrel dogs was studied. The CPAP and EPAP at 5, 10, 15, and 20 cm H2O were alternately applied to all animals. ⋯ Neither expiratory transpulmonary pressure nor delta FRC with CPAP differed significantly from that with EPAP at all levels (p greater than 0.05). These data suggest that CPAP and EPAP, when applied at the same expiratory pressure, result in an equivalent increase in FRC due to passive mechanical distention of the lungs.
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Case Reports
Persistent hypoxemia due to patent foramen ovale in a patient with adult respiratory distress syndrome.
This report describes a patient in the recovery phase of the adult respiratory distress syndrome in whom the persistence of severe hypoxemia was not corrected by a high fractional concentration of oxygen in the inspired gas and positive end-expiratory pressure. A right-to-left interatrial shunt was diagnosed by M-mode and cross-sectional echocardiography with saline injection, and the presence of a patent foramen ovale was confirmed at the time of cardiac surgery.
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Pulmonary mucormycosis is an uncommon, but important, opportunistic fungal pneumonia which is often diagnosed post-mortem. This review emphasizes clinical and pathologic characteristics of pulmonary mucormycosis that differentiate this infection from other fungal pneumonias. ⋯ Early consideration of this diagnosis, along with aggressive diagnostic evaluation, are critical to effective therapy and patient survival. While treatment with amphotericin B is the mainstay of therapy for pulmonary mucormycosis, diabetics with endobronchial disease may benefit from early, aggressive surgical resection of the involved lung tissue.
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Two patients with the adult respiratory distress syndrome (ARDS) were placed on pressure-controlled inverse-ratio ventilation (IRV) when their condition deteriorated despite optimal treatment with intermittent mandatory ventilation and positive end-expiratory pressure. In the first case, high peak airway pressure was reduced by 50 percent with the institution of IRV. In the second, refractory hypoxemia was eliminated by using an inspiratory-to-expiratory ratio of 4:1. These cases show that IRV may offer certain advantages in the treatment of severe ARDS.