The Effect of Caffeine on Diaphragmatic Activity and Tidal Volume in Preterm Infants

Objective To determine the effect of caffeine on diaphragmatic activity, tidal volume (Vt ), and end-expiratory lung volume (EELV) in preterm infants. Study design Using transcutaneous electromyography of the diaphragm (dEMG), we measured diaphragmatic activity from 30 minutes before (baseline) to 3 hours after administration of an intravenous caffeine-base loading dose in 30 spontaneously breathing preterm infants (mean gestational age, 29.1 ± 1.3 weeks), most of whom were on noninvasive respiratory support. Diaphragmatic activity was expressed as the percentage change in dEMG amplitude, area under the curve, respiratory rate, and inspiratory and expiratory times. Using respiratory inductive plethysmography, we measured changes in Vt and EELV from baseline. These outcome variables were calculated at 8 fixed time points after caffeine administration (5, 15, 30, 60, 90, 120, 150, and 180 minutes) and compared with baseline. Results Caffeine administration resulted in rapid (within 5 minutes) increases in dEMG amplitude (median, 43%; IQR, 24%-63%; P