Abstract
BACKGROUND: To evaluate changes in end-expiratory lung impedance (EELI), a surrogate for end-expiratory lung volume (EELV), during a minimal-handling extubation protocol in very preterm infants in prone position. The protocol aimed to minimize interruptions in positive end-expiratory pressure (PEEP) delivery. METHODS: This was a prospective observational study including preterm infants born before 32 weeks' gestation who underwent elective extubation without conditions negatively impacting lung aeration or perfusion. Participants were recruited at the University Hospital Zurich (June 2023-March 2024). We compared a novel extubation protocol that minimizes infant handling to a conventional protocol. Lung volume changes were continuously monitored noninvasively via electrical impedance tomography (EIT), capturing end-expiratory lung impedance (EELI) as a proxy for end-expiratory lung volume (EELV). The pulse rate (PR), oxygen saturation (SpO2), and inspired oxygen fraction (FiO(2)) were recorded continuously. Changes in EELI and cardiorespiratory parameters were compared to those at baseline (before the infant was first handled). RESULTS: Fifteen extubations were analysed. At initiation of non-invasive ventilation (NIV), the median EELI decreased by -0.68 AU/kg (IQR: -0.99 to -0.21), reflecting a median EELV loss of 27.7 ml/kg (IQR: -40.6 to -8.6). The greatest EELI loss occurred during tape removal (-0.24 AU/kg, p(adj) = 0.025), whereas the greatest recovery occurred during stabilization (0.31 AU/kg, p(adj) = 0.025). The duration of extubation was 1.7 min (IQR: 1.3-2.0), with a 2-second median interval (IQR: 1-4) between tube removal and NIV. Oxygen saturation remained stable (p(adj) = 0.32). CONCLUSIONS: While minimal handling did not prevent lung volume loss during extubation, a stabilization period preceding extubation facilitated partial lung volume restoration.