First real-time imaging of bronchoscopic lung volume reduction by electrical impedance tomography.

Background: Bronchoscopic lung volume reduction (BLVR) with one-way endobronchial valves (EBV) has better outcomes when the target lobe has poor collateral ventilation, resulting in complete lobe atelectasis. High-inspired oxygen fraction (FO) promotes atelectasis through faster gas absorption after airway occlusion, but its application during BLVR with EBV has been poorly understood. We aimed to investigate the real-time effects of FO on regional lung volumes and regional ventilation/perfusion by electrical impedance tomography (EIT) during BLVR with EBV.

Effects of Lung Injury and Abdominal Insufflation on Respiratory Mechanics and Lung Volume During Time-Controlled Adaptive Ventilation.

Backgroud: Lung volume measurements are important for monitoring functional aeration and recruitment and may help guide adjustments in ventilator settings. The expiratory phase of airway pressure release ventilation (APRV) may provide physiologic information about lung volume based on the expiratory flow-time slope, angle, and time to approach a no-flow state (expiratory time [T]). We hypothesized that expiratory flow would correlate with estimated lung volume (ELV) as measured using a modified nitrogen washout/washin technique in a large-animal lung injury model.

System identification of proportional solenoid valve dynamics.

We present a system identification technique for the characterisation of the linearity and dynamic response of a PSOL valve and its corresponding electronic control unit (ECU) using bandlimited white noise, as well as pseudo random "non-sum non-difference" (NSND) waveforms consisting of mutually prime frequencies to mitigate the effects of nonlinear distortions. The parameters of several transfer function models were simultaneously estimated from the voltage-flow frequency response using a nonlinear gradient descent technique. Candidate transfer function models were assessed using the mean squared residual (MSR) criterion and the corrected Akaike information criterion (AICc).

Shared Ventilation in the Era of COVID-19: A Theoretical Consideration of the Dangers and Potential Solutions.

Background: The use of shared ventilation, or the simultaneous support of multiple patients connected in parallel to a single mechanical ventilator, is receiving considerable interest for addressing the severe shortage of mechanical ventilators available during the novel coronavirus pandemic (COVID-19). In this paper we highlight the potentially disastrous consequences of naïve shared ventilation, in which patients are simply connected in parallel to a ventilator without any regard to their individual ventilatory requirements. We then examine possible approaches for individualization of mechanical ventilation, using modifications to the breathing circuit that may enable tuning of individual tidal volumes and driving pressures during either volume-controlled ventilation (VCV) or pressure-controlled ventilation (PCV).