Chest
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Bronchoscopic phototherapy is available now for 2 distinct categories of tracheobronchial cancer: roentgenographically occult superficial squamous cell carcinoma and advanced malignancy causing significant airway obstruction. Laboratory and clinical experience show that the photodynamic effect of hematoporphyrin derivative phototherapy (HpD-PT) may be useful for treating superficial cancers that penetrate less than 5 mm into bronchial mucosa. The larger, obstructing cancers are better managed by high-power laser sources, such as the YAG laser, which are effective by hyperthermal photocoagulation, thermal necrosis, and tissue vaporization.
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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.