Abstract

A pneumatic capsule applied to the sub-xiphisternum provides a signal of spontaneous respiratory effort. Purpose-written software analyses this waveform to determine spontaneous inspiratory and expiratory times. Algorithms reject artefacts. The computerised system allows continuous measurement of spontaneous inspiratory and expiratory times to be made during intermittent positive pressure ventilation. The accuracy of the system was measured in 17 infants ventilated for respiratory distress syndrome: median (range) gestation and birth weight were 31 (25-38) weeks and 1195 (506-3260) g. The new technique can measure inspiratory time of individual breaths with a mean error of 5.4% and expiratory time with a mean error of 1.6%.