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.
D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D008170:Lung Compliance; D008297:Male; D010993:Plethysmography, Whole Body; D012119:Respiration; D012126:Respiratory Dead Space