137 A Non Invasive Approach to Assess Compliance of Preterm Newborns with Persistent Active Respiratory Movements During Synchronized Intermittent Mandatory Ventilation: Preliminary Results

Abstract

Background: The evaluation of respiratory mechanics of the preterm infant requiring mechanical ventilation is used to optimize the assisted ventilation settings and reduce baro-volo-traumatism. This is a difficult task when using synchronized intermittent mandatory ventilation (SIMV). Indeed the SIMV is currently used when weaning very preterm infants from assisted ventilation. Aims: We present preliminary results to assess a new, non invasive, approach to evaluate compliance, when active respiratory movements persist during synchronized intermittent mandatory ventilation. Design/Methods: Four premature newborns (1 male, 3 female, gestational age: 27,3 (26–33) wks, birth weight: 975 (635–1940) g, postnatal age: 3 (1–9) days), hospitalized for treatment of hyaline membrane disease (HMD), were explored for the evaluation of total respiratory compliance. The technique we used is non invasive and does not need any adaptation of the usual preterm care in the NICU. The airways pressure (Paw) and pulmonary flow were recorded from the respirator Babylog 8000®, Dräger. Tidal volume (TV) was obtained by numerical integration from the pulmonary flow signal for each respiratory cycle. Since patient inspiratory effort during spontaneous and mechanicals assisted respiratory cycles are considered equals, we estimated the mean tidal volume of passive cycles (TVp) as: TVp = mean TV assisted cycles–mean TV spontaneous cycles. The mechanical compliance of the respiratory system (Csr) was calculated by the relation: Csr = TVp/(max Paw –PEEP). Results are expressed as median (extremes). Results: TVp: 4,55 (2,7–12,2) ml; max Paw: 14,6 (14,3–19,6)cmH2O; PEEP: 3(2,6–3,6) cmH2O; Csr: 0,4 (0,33–0,57)ml/cmH2O/kg. Conclusions: These preliminary results agree with expected data for premature newborns with HMD. This new and non invasive technique could be used for further studies to evaluate the compliance during synchronized intermittent mandatory ventilation.