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Biomedical subjects

D D Sommer

Publications and source records attributed to D D Sommer.

4 recordsLinked to original sources
PubMed1996

PCO2 affects tracheal tone during apnea in anesthetized dogs.

We hypothesized that CO2, like hypoxia and withdrawal of pulmonary slowly adapting receptor input, would cause tracheal constriction during neural apnea (absence of phrenic activity). In seven anesthetized paralyzed dogs ventilated to neural apnea, we increased arterial PCO2 (PaCO2) in steps by adding CO2 to the inspirate while keeping ventilation constant. Increases in PaCO2 caused tracheal constriction during neural apnea in all dogs; 69 +/- 26 (SD)% of the change in tracheal diameter occurred during neural apnea. Average sensitivity of tracheal diameter to CO2 was 0.44 mm/Torr PaCO2. Our data suggest that central chemoreceptor inputs to brain stem neurons controlling smooth muscle of the extrathoracic airway bypass central mechanisms generating inspiration.

Animals↗
PubMed1995

Dynamic measurement of tracheal diameter in dogs.

We describe and validate a new minimally invasive method for continuous measurement of tracheal diameter in anesthetized dogs. The method is based on measuring displacement of water into and out of a modified endotracheal tube cuff placed in the trachea. The system was calibrated to allow tracheal diameter to be calculated from known cuff volume. The resolution of the method in measuring changes in tracheal diameter is 0.1 mm over a range of approximately 10-25 mm. The apparatus was tested in five dogs by observing the response of the trachea to four stimuli previously shown to alter tracheal tone: stimulation of nasal mucosa, hyperinflation of the lungs, induction of hypocapnea, and infusion of atropine. The observed changes in tracheal diameter were generally consistent with those of previous studies. The direction and extent of changes in tracheal diameter in response to the test conditions were confirmed by fluoroscopy. We conclude that continuous measurement of volume changes in the cuff reflects corresponding changes in tracheal diameter.

Animals↗
PubMed1994

Improvised automatic lung ventilation for unanticipated emergencies.

OBJECTIVES: To design an improvised circuit that can be used to extend the capability of a single ventilator to ventilate two or more patients and that can be assembled from readily available parts in times of unanticipated emergency. DESIGN: Research and development, followed by technical analysis and evaluation. SETTING: Biomedical laboratory. MEASUREMENTS AND MAIN RESULTS: We describe two circuits that can be assembled from readily available inexpensive components to function as improvised ventilators. One circuit requires only a central mushroom valve driver and an additional source of fresh gas for each patient. The other circuit is configured as a number of secondary circuits in parallel, connected to a single ventilator. We constructed and tested the circuits using mechanical lung simulators. The secondary circuit configuration was more efficient in terms of fresh gas usage, but was more complex regarding operation and trouble-shooting. CONCLUSIONS: These two improvised circuits can extend the capability of a standard volume-cycled ventilator to provide automatic ventilation of the lungs in times of disaster.

Emergencies↗