Expiratory Diaphragmatic Recruitment in Acute Respiratory Distress Syndrome. A Happy Coincidence or Much More?

• Published in: American journal of respiratory and critical care medicine Vol. 195; no. 12; pp. 1548 - 1550
• Main Authors: Laghi, Franco, Shaikh, Hameeda
• Format: Journal Article
• Language: English
• Published: United States American Thoracic Society 15-06-2017
• Subjects: Asthma; Humans; Investigations; Mechanics; Muscle function; Positive-Pressure Respiration; Respiratory distress syndrome; Respiratory Distress Syndrome, Adult; Respiratory therapy; Sepsis; Teleology; Ventilation
• ISSN: 1073-449X; 1535-4970
• DOI: 10.1164/rccm.201612-2503ED

[...]EELV cannot simply be the result of a balance between elastic recoil pressures of the lung and a relaxed chest wall. [...]lung volume does not fall to the level achieved by complete muscle relaxation, even in the absence of expiratory flow limitation (7). In this issue of the Journal, Pellegrini and colleagues (pp. 16081616) expand our understanding of postinspiratory inspiratory muscle activity by investigating a pig model of mild acute respiratory distress syndrome (8). [...]they had to rely on complex data processing to account for the movement of the diaphragm relative to the electrodes to eliminate the influence of the electrocardiogram, motion-induced disturbances, and background noise (10). Type la sensory fibers are facilitatory on a motoneurones (13). [...]a reduction in type la afferent discharge, if it occurred, could have participated in the PEEPassociated decrease of postinspiratory diaphragmatic activity (8). [...]an intensivist cannot know what gain factor to use when delivering PEEP according to the diaphragmatic electrical signal. [...]during exhalation, the diaphragm lengthens, making postinspiratory diaphragmatic activity an eccentric contraction. [...]although postinspiratory diaphragmatic contraction might be beneficial to the lung parenchyma and gas exchange (8), it could be detrimental to the muscle. While waiting for such research to bear fruit, physicians should strive to limit the duration of mechanical ventilation and, when possible, choose modes that require some degree of respiratory muscle activation, while avoiding excessive patient effort (16).