Extubation generates lung volume inhomogeneity in preterm infants

AbstractObjectiveTo evaluate the feasibility of EIT to describe the regional tidal ventilation (VT) and change in end-expiratory lung volume (EELV) patterns in preterm infants during the process of extubation from invasive to non-invasive respiratory support.DesignProspective observational studySettingSingle-centre tertiary neonatal intensive care unitPatientsPreterm infants born <32 weeks gestation who were being extubated to nasal continuous positive airway pressure (nCPAP) as per clinician discretion.InterventionsElectrical Impedance Tomography measurements were taken in supine infants during elective extubation from synchronised positive pressure ventilation (SIPPV) before extubation, during and then at 2 and 20 minutes after commencing nCPAP. Extubation and pressure settings were determined by clinicians.Main outcome measuresGlobal and regional ΔEELV and ΔVTwere measured. Heart rate, respiratory rate and oxygen saturation were measured throughout.ResultsThirty infants of median (range) 2 (1, 21) days were extubated to a median (range) CPAP 7 (6, 8) cmH2O. SpO2/FiO2ratio was mean (95% CI) 50 (35, 65) lower 20 minutes after nCPAP compared with SIPPV. EELV was lower at all points after extubation compared to SIPPV, and EELV loss was primarily in the ventral lung (p=0.04). VTwas increased immediately after extubation, especially in the central and ventral regions of the lung, but the application of nCPAP returned VTto pre-extubation patterns.ConclusionsLung behaviour during the transition from invasive positive pressure ventilation to CPAP at moderate distending pressures is variable and associated with lung volume loss in the ventral lung.