Extubation generates lung volume inhomogeneity in preterm infants

Abstract

ObjectiveTo evaluate the feasibility of electrical impedance tomography (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 study.SettingSingle-centre tertiary neonatal intensive care unit.PatientsPreterm infants born <32 weeks’ gestation who were being extubated to nasal continuous positive airway pressure as per clinician discretion.InterventionsEIT measurements were taken in supine infants during elective extubation from synchronised positive pressure ventilation (SIPPV) before extubation, during and then at 2 and 20 min after commencing nasal continuous positive applied pressure (nCPAP). Extubation and pressure settings were determined by clinicians.Main outcome measuresGlobal and regional ΔEELV and ΔVT, 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) cm H2O. SpO2/FiO2 ratio was a mean (95% CI) 50 (35, 65) lower 20 min after nCPAP compared with SIPPV. EELV was lower at all points after extubation compared with SIPPV, and EELV loss was primarily in the ventral lung (p=0.04). VT was increased immediately after extubation, especially in the central and ventral regions of the lung, but the application of nCPAP returned VT to pre-extubation patterns.ConclusionsEIT was able to describe the complex lung conditions occurring during extubation to nCPAP, specifically lung volume loss and greater use of the dorsal lung. EIT may have a role in guiding peri-extubation respiratory support.