Why NIV setting definitions may be tricky: Trigger sensitivity

Noninvasive ventilation (NIV) is widely used in children. The spontaneous/timed (S/T) mode is the most common used mode for home NIV. Different devices are available, and the manufacturers are free to name the modes and define the settings, with no regulation. In particular, the definitions of the trigger sensitivities still differ between manufacturers and/or devices. The inspiratory trigger (TgI) sensitivity may be set according to a numerical or word-rating scale, while the expiratory trigger (TgE) sensitivity may be set as a percentage of the peak inspiratory flow, or using a numerical or word rating scale which correspond to specific predefined percentages of inspiratory flow. Moreover, the TgE sensitivity may be set according to the peak inspiratory flow or to the diminution of peak inspiratory flow, which may be very confusing. Patient-ventilator asynchrony (PVA) may be due to an inadequate comprehension of the settings by the user, which is challenging. We report here the cases of four children and adolescents with an incorrect setting of the TgI and/or TgE, leading to PVA. This pleads for a harmonization of the definitions of the settings, and in particular of the trigger sensitivities. In the meanwhile, NIV professionals should be aware of the different definitions to avoid setting errors leading to PVA.