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Biomedical subjects

B H Culver

Publications and source records attributed to B H Culver.

23 records · Page 2Linked to original sources
PubMed1978

Pressure outside the extrapulmonary airway in dogs.

We have measured the static and dynamic transmural pressures of extrapulmonary airways during positive pressure lung inflation in anesthetized dogs suspended in the standing position. Thin, fluid-filled catheters measured pressures within and on the anterior surface of the airways in the mediastinum and neck. The change from mediastinal to cervical static extra-airway pressures (Pea) was not abrupt but occurred through the thoracic outlet and the root of the neck. The static Pea in the mediastinum was more positive than pleural pressure when lung volume was increased with positive pressures. During forced deflation equal pressure points (EPP) were in labor bronchi from which airway narrowing extended towards the mouth. Under these conditions, the dynamic mediastinal Pea mouthward of the EPP remained close to pleural pressures even at high volumes. This suggested that forces of restitution generated in the surrounding tissues by the narrowing of the airways did have a small effect in reducing the pressure affecting their anterior surface.

Animals↗
PubMed1977

Pulmonary arteriovenous fistulas: increase in shunt at high lung volume.

Intrapulmonary shunt measured in the sitting position by the oxygen breathing method increased at total lung capacity in 7 of 8 patients with pulmonary arteriovenous fistulas. This may explain the clinically noted increased murmur over a fistula on inspiration. The finding of an increased intrapulmonary shunt at total lung capacity might suggest the diagnosis in equivocal cases and provide a convenient test for follow-up after surgery.

Arteriovenous Fistula↗
PubMed1975

Cardiac limitation to maximal oxygen transport and changes in components after jogging across the US.

Observations were made before and 3-5 days after prolonged endurance jogging an average of 42 miles/day, 6 days/wk for 2.5 mo by a young male adult who voluntarily initiated a run across the United States. Both arterial PO2 and lactic acid increased. In each instance, the first limitation in circulatory delivery of oxygen was a plateau in stroke volume and cardiac output. Afterward, pulse deficit and systemic arterial pressure fell with exercise and heart rate accelerated. Although there was no change in oxygen transport (Q X CAO2), a reduction in stroke volume was exactly balanced by a rise in arterial oxygen content. Vital capacity, residual volume, and total lung capacity and diffusion capacity for carbon monoxide, hematocrit, and red cell mass increased, while plasma volume diminished and heart size and total blood volume were unchanged.

Adult↗