Assisted mechanical ventilation using resistive and elastic unloading

Abstract

During assisted mechanical ventilation with respiratory unloading, the applied airway pressure follows quasi-instantaneously the infant's pattern of spontaneous breathing. This allows the infant to fully control the amplitude and timing of each breath. The ventilator receives the flow signal of spontaneous breathing as input and quasi-instantaneously provides an airway pressure output in proportion to the volume signal and/or the airflow signal of spontaneous breathing. With elastic unloading, the airway pressure increases during inspiration in proportion to the volume signal to oppose lung elastic recoil pressure. During resistive unloading, the airway pressure increases above baseline (PEEP) in proportion to inspiratory airflow. This decreases resistive work of breathing. The clinician adjusts the gain of the assist (the ratios of airway pressure per unit of volume and/or airflow) to tailor the pressure waveforms to the type (restrictive and/or obstructive) and degree of lung disease.