Hering-Breuer reflex, lung volume and position in prematurely born infants

Objectives To investigate the effect of position on the strength of the Hering–Breuer reflex in prematurely born infants and determine whether any differences seen were related to differences in lung or tidal volume between positions. Working Hypothesis Position related differences in the strength of the Hering–Breuer reflex relate to differences in lung or tidal volume. Study Design Prospective observational study. Patient/Subject Selection Eighteen infants, median gestational age 30 (range 25–32) weeks were studied. Methodology Infants were examined in the supine and prone position, each position was maintained for 2 hr. At the end of each 2‐hr period, the strength of the Hering–Breuer reflex was assessed by determining the prolongation of expiration following an end inspiratory occlusion. In addition, tidal volume and functional residual capacity (FRC) were assessed in each position. Results The strength of the Hering–Breuer reflex was greater (P = 0.01) and the mean FRC was higher (P