Cycling the Breath in Noninvasive Home Ventilation

Spontaneous/timed (ST) mode is widely used for long-term noninvasive ventilation (NIV) in adults and children. It combines controlled, assisted, and spontaneous breaths. Cycling refers to the switch from inspiration to exhalation. In ST mode, different cycling mechanisms coexist. In spontaneous breathing, cycling is set by the expiratory trigger sensitivity (TgE) based on the inspiratory flow signal, which results in variable inspiratory times (Ti) and appears to be more physiological. In the case of controlled breathing or unintentional leaks, the cycling is time-dependent according to the set backup Ti or Ti max, respectively. Cycling is an important parameter to set adequately to avoid patient-ventilator asynchronies. This article gathers all the information about cycling in long-term NIV, presenting the cycling settings for different devices, addressing cycling issues, and detailing how to set the cycling criteria. Advanced monitoring with statistics and waveforms is discussed to detect early and delayed cycling.