Interrupter technique for measurement of respiratory mechanics in anesthetized humans

Flow (V), volume (V), and tracheal pressure (Ptr) were measured throughout a series of brief (100 ms) interruptions of expiratory V in six patients during anesthesia (halothane-N2O) and anesthesia-paralysis (succinylcholine). For the latter part of spontaneous expiration and throughout passive deflation during muscle paralysis, a plateau in postinterruption Ptr was observed, indicating respiratory muscle relaxation. Under these conditions, passive elastance of the total respiratory system (Ers) was determined as the plateau in postinterruption Ptr divided by the corresponding V. The pressure-flow relationship of the total system was determined by plotting the plateau in Ptr during interruption against the immediately preceding V. Ers averaged 23.5 +/- 1.9 (SD) cmH2O X l-1 during anesthesia and 25.5 +/- 5.4 cmH2O X l-1 during anesthesia-paralysis. Corresponding values of total respiratory system resistance were 2.0 +/- 0.8 and 1.9 +/- 0.6 cmH2O X l-1 X s, respectively. Respiratory mechanics determined during anesthesia paralysis using the single-breath method (W.A. Zin, L. D. Pengelly, and J. Milic-Emili, J. Appl. Physiol. 52: 1266-1271, 1982) were also similar. Early in spontaneous expiration, however, Ptr increased progressively during the period of interruption, reflecting the presence of gradually decreasing antagonistic (postinspiratory) pressure of the inspiratory muscles. In conclusion, the interrupter technique allows for simultaneous determination of the passive elastic as well as flow-resistive properties of the total respiratory system. The presence of a plateau in postinterruption Ptr may be employed as a useful and simple criterion to confirm the presence of respiratory muscle relaxation.     

Cytochemical observations of hemocytes in decapod brachyuran crustacea (author's transl)]

Hemocytes from two species of crabs, Eriocheir sinensis and Carcinus maenas, have been submitted to different cytochemical reactions in order to bring out the nature of granules' content, either by specific coloration or be enzymatic digestion. Light as well as electron microscopy has been used. The granules appeared to be made essentially of basic proteins, rich in arginin and disulfide bridges but poor in tyrosin. These proteins are linked with nonglycogenic carbohydrates. Glycogen deposits of varied size are restricted to the cytoplasm in all the different cell-types but have never been detected inside the granules themselves. Lipids are poorly represented. The bulk of the granule material is made of neutral mucopolysaccharides although minute amounts of acid mucosubstances could be found in some instances.     

Effect of mechanical loading on displacements of chest wall during breathing in humans

Using a respiratory inductive plethysmograph (Respitrace) we studied thoracoabdominal movements in eight normal subjects during inspiratory resistive (Res) and elastic (El) loading. The magnitude of loads was chosen so as to produce a fall in inspiratory mouth pressure of 20 cmH2O. The contribution of rib cage (RC) to tidal volume (VT) increased significantly from 68% during quiet breathing (QB) to 74% during El and 78% during Res. VT and breathing frequency did not change significantly. During loading a phase lag was present on inspiration so that the abdomen led the rib cage. However, outward movement of the abdomen ceased in the latter part of inspiration, and the RC became the sole contributor to VT. These observations suggest greater recruitment of the inspiratory musculature of the RC than the diaphragm during loading, although changes in the mechanical properties of the chest wall may also have contributed. Indeed, an increase in abdominal end-expiratory and end-inspiratory pressures was observed in five out of six subjects, indicating abdominal muscle recruitment which may account for part of the reduction in abdominal excursion. Both Res and El increased the rate of emptying of the respiratory system during the ensuing unloaded expiration as a result of a reduction in rib cage expiratory-braking mechanisms. The time course of abdominal displacements during expiration was unaffected by loading.     

Etude cytochimique des hémocytes des crustacés décapodes brachyoures

Histochemistry and Cell Biology - Les hémocytes de deux espèces de crabes, Eriocheir sinensis et Carcinus maenas, ont été soumis à différentes réactions...