Ventilatory Values Measured in Normal Newborns by Respiratory Inductive Plethysmography

Abstract

Respiratory inductive plethysmography (RIP) is a method used to measure pulmonary function without physical connection of measuring devices to the airway. Wire coils sewn into elastic bands placed around the rib cage and abdomen transmit changes in self-inductance through an oscillator circuit. Changes in the cross-sectional area of the rib cage and abdomen as a result of ventilatory movement are calibrated to an integrated pneumotachograph signal so that the rib-cage and abdomen sum signal becomes a quantitative measurement of tidal volume. We measured the ventilatory pattern of 24 term newborn infants during a 1-minute steady-state period of quiet breathing during which no sedation was used. The following mean values, with standard deviations, were recorded: minute ventilation 1.58 ± 0.46 L, frequency 60.3 ± 17.4 breaths/min, and tidal volume 24.4 ± 4.20 ml. Additional breathing pattern components not previously reported to have been measured by noninvasive ventilatory monitoring of newborn infants were inspiratory time 0.41 ± 0.08 s, mean inspiratory flow 54.7 ± 17.1 ml/s, fractional inspiratory time 0.49 ± 0.04, expiratory time 0.50 ± 0.14 s, mean expiratory flow 54.1 ± 11.3 ml/s, and percentage of rib-cage contribution to tidal volume 30.8 ± 11.1%. (Respir Care 1985;30:174-178.)