Carbon monoxide poisoning.

Carbon monoxide (CO) is a ubiquitous toxin that may reversibly bind various heme-containing proteins in the human body. These proteins (hemoglobin, myoglobin, cytochrome P450, cytochrome oxidase) may be bound by the CO at sites which are also responsible for O2 transport. Since the CO-heme bond is less dissociable than the O2-heme bond, severe disruption of normal O2 transport may occur.

Metastatic endotracheal tumor from ovarian carcinoma.

This report describes a patient with acute airways obstruction and respiratory failure secondary to a large endotracheal metastasis from a primary ovarian carcinoma first detected seven years previously. Associated airflow obstruction due to mucus impaction contributed significantly to the development of respiratory failure. The tumor responded to radiotherapy, and radiologic evidence for tracheal obstruction was no longer present five months after irradiation.

False negative biopsy in Pneumocystis carinii pneumonia.

Unlike most pneumonias, the diagnosis of Pneumocystis carinii pneumonia is based solely on identifying organisms by stain, usually with methenamine-silver. Because of technical problems involved with adequate staining, control samples usually are done concurrent with tissue specimens to be examined. Lung containing fungi often is used as a control.

Comparison of the effects of continuous negative external chest pressure and positive end-expiratory pressure on cardiac index in dogs.

Continuous negative external chest pressure was used to increase the functional residual capacity in 6 dogs, and the effects were compared with the effects of increasing functional residual capacity using positive end-expiratory pressure. Cardiac index and mixed venous O2 stauration each decreased from control values during positive end-expiratory pressure, but did not decrease with continuous negative external chest pressure. Continuous negative external chest pressure may provide an alternative to positive end-expiratory pressure for increasing the functional residual capacity of patients in whom the latter causes unacceptable decreases in venous return and cardiac output.

Exercise tolerance at 4 and 6 ATA.

Seven normal male subjects performed 5-min bicycle exercise ranging from 50-100% maximum oxygen uptake at 4 ATA and three were also studied at 6 ATA. At all pressures, the subjects breathed 0.2 ATA O2 plus nitrogen.