Factors influencing humidification in high-frequency jet ventilation

A new method of water nebulization for high-frequency jet ventilation (HFJV) using a coaxial saline infusion is described. A bench study was performed to investigate how alteration of the HFJV variables affects humidity using this method of humidification. The variables examined included the water flow rate (0.1, 0.25, 0.5, and 1.0 ml/min), cannula OD 2.1 mm (14 ga) and 1.4 mm (17 ga), ventilation rate (60, 80, 100, and 120 beat/min), inspiratory/expiratory (I/E) ratio (0.25, 0.67, and 1.5), and driving pressure (600, 900, 1200, and 1500 torr). Increasing water flow rate increased humidity. Humidity decreased with increased driving pressure, I/E ratio, and cannula OD. Humidity is not much affected by ventilation rate.