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Biomedical subjects

L D Pengelly

Publications and source records attributed to L D Pengelly.

33 records · Page 2Linked to original sources
PubMed1977

Changes in lung mechanics induced by acute isocapnic hypoxia.

We measured lung mechanics in seven healthy males during acute isocapnic hypoxia (PAO2 = 40-50 Torr; PACO2 = 38-42 Torr). Hypoxia was accompanied by increases in total lung capacity (mean increase +/- SD; 0.40 +/- 0.24 liters; P less than 0.005) functional residual capacity (0.34 +/- 0.25 liters; P less than 0.01) and residual volume (0.56 +/- 0.44 liters; P less than 0.02) in all subjects. Specific conductance of the lung decreased during hypoxia (P less than 0.02). The static deflation pressure-volume curve of the lung was shifted upward during hypoxia in all subjects. Resting end-expiratory recoil pressure of the lung was slightly, but not significantly lower during hypoxtic expiratory lung compliance was greater during hypoxia (0.39 +/- 0.04 l/cmH2O) than control measurements (0.31 +/- 0.05 l/cmH2O; P less than 0.005). No change was noted in dynamic lung compliance. All changes in lung mechanics were reversed within three minutes of reoxygenation. We conclude that acute isocapnic hypoxia increases total lung capacity in man and suggest that this may be due to the effect of hypoxia on the airways and pulmonary circulation.

Adult↗
PubMed1975

Effect of added elastances on the first loaded breath in man.

Tidal volume together with end-inspiratory pressure was measured in four seated healthy men, during normal breathing and during single inspirations taken from a series of rigid containers which provided added elastances (range: 5-70 cmH2O/l). Experiments were performed both during quiet breathing and during ventilation increased by added dead space. Added elastic loads always resulted in a decreased tidal volume. This decrease was partly compensated by increased pressure developed by the inspiratory muscles; being more so with greater added elastance, control ventilation, or both. Analysis of our results indicates that the load-compensatory response may be attributed to changes in mechanical impedance of the ventilatory pump, due to the mechanical arrangement and the intrinsic properties of the inspiratory muscles (force-length and force-velocity relationships), changes in respiratory frequency with increasing ventilation, and to vagally mediated load compensation.

Adult↗
PubMedDate not supplied

Effects of ozone exposure in Canadians and Southern Californians. Evidence for adaptation?

Comparison of published reports on physiological effects of exposure to ozone (O3) suggests that Canadians are more reactive than southern Californians. Responses of subjects and experimental methods were compared in a cooperative investigation of this apparent difference in reactivity. Four Canadians and four Californians were exposed to 0.37 ppm O3 in purified air at 21 degrees C and 50% relative humidity for 2 hours with intermittent light exercise. Exposures to purified air alone served as controls. Responses of subjects were similar to those observed previously: Canadians on the average showed greater clinical and physiological reactivity to exposure than did Californians, who were no more than minimally reactive. Canadians also showed larger increases in erythrocyte fragility following exposure. No methodological differences sufficient to explain different results of previous studies were found. Although other possible explanations have not been ruled out entirely, adaptation of southern Californians to chronic ambient O3 exposure is a rational hypothesis to explain these results.

Acetylcholinesterase↗