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Biomedical subjects

R E Hyatt

Publications and source records attributed to R E Hyatt.

At least 109 records · Page 6Linked to original sources
PubMed1971

Ventilatory mechanics and expiratory flow limitation during exercise in patients with obstructive lung disease.

The interrelationships among transpulmonary pressure, flow, and volume during exhausting exercise were studied in 12 males with chronic obstructive lung disease. Expiratory pressure during exercise was compared with flow-limiting pressure (P(max)) measured at rest. In 11 patients, expiratory pressure during exercise exceeded P(max), indicating that ventilation became mechanically inefficient. P(max) values of the patients were lower than those of normal subjects. Evidence of expiratory flow augmentation during exercise was noted in two subjects. Since 10 subjects achieved maximal expiratory flow predicted from flow-volume curves when heart rate was not maximal, we conclude that exercise capacity in most subjects was clearly limited by the deranged ventilatory apparatus. Elevations in mean intrathoracic pressure during exercise also may interfere with venous return and impose an additional limitation.

Adult↗
PubMed1969

Ventilatory mechanics and expiratory flow limitation during exercise in normal subjects.

We have examined the interrelationships among transpulmonary pressure, flow, and volume during exhausting exercise in 10 normal adult males. Expiratory transpulmonary pressures during exercise were compared with flow-limiting pressures measured at rest by two techniques. In no case did pressures developed during exercise exceed to an appreciable extent the flow-limiting pressures. This indicates that, during near-maximal exercise, ventilation remains efficient as judged in terms of the pressure-volume relationships of the lung. The mechanical properties of the lung do not appear to limit ventilation during exhausting exercise in normal subjects. We could find no relationship between the magnitude of transpulmonary pressure and exercise limitation. There was no evidence that lung mechanics changed during exhausting exercise in normal subjects. The two methods for estimating expiratory flow-limiting pressures, the orifice technique and the isovolume pressure-flow method, gave similar results.

Adult↗