UvA - DARE ( Digital Academic Repository ) The relative impact of respiratory muscle activity on tidal flow and lung volume in infants

Introduction: Infants with chronic lung disease (CLD) have a high capacity to maintain normal functional lung volume despite their alterations in lung mechanics. We hypothesise that they achieve this by altering breathing pattern and dynamical elevation of lung volume, leading to differences in the relationship between respiratory muscle activity (rEMG), flow pattern and lung volume, whereby timing indices derived from rEMG could be new non-invasive bedside markers of altered lung mechanics in CLD. Methods: Lung function and transcutaneous rEMG were measured simultaneously in 20 infants with CLD (median postconceptional age 45 wks) and 39 healthy age matched controls during quiet sleep. We compared amplitude and coefficient of variation (CV) of rEMG and their temporal relationship to flow and lung volume (FRC) between these two groups. Results: The time between start of inspiratory muscle activity and resulting flow (tria) in relation to respiratory cycle time was significantly longer in infants with CLD. Although FRC was similar associations between FRC and tria and post-inspiratory activity corrected for respiratory cycle time, the breath to breath variability (CV) of the diaphragm tEMG and the response to a resistive load significantly differed between groups. Conclusion: The temporal relationship of rEMG to flow and the loss of adaptive variability provide additional information on coping mechanisms in infants with CLD not obvious in FRC measurements alone. This new technique could be used for noninvasive bedside monitoring of CLD as well as during EMG triggered ventilation in these infants in future trials.