Classifying Different Types of Double Triggering Based on Airway Pressure and Flow Deflection in Mechanically Ventilated Patients

Identifying Patient-Ventilator Asynchrony Using Waveform Analysis

“…The main characteristic of ineffective efforts is to produce an airway pressure drop in the pressure/time waveform, caused by the inspiratory effort of the patient, which decreases the airway pressure and, a change in the expiratory flow (which tends to return to zero due to the inspiratory effort of the patient) without the delivery of a breath from the ventilator [4,14][ Figure 1]. This type of PVA is the most frequent and occurs more frequently during the expiratory phase (may also occur during the inspiratory phase), in all modes [4,15].…”

“…Thille et al found that factors associated with a high incidence of double-triggering were: a low pao2/FIO2 ratio, ACV (assist-control ventilation mode), a shorter inspiratory time, a high maximal inspiratory pressure, and a high level of PEEP [4,22]. Double trigger can be defined as "two cycles separated by a very short expiratory time, defined as less than one-half of the mean inspiratory time, the first cycle being patient-triggered" [4,15,24]. This type of PVA can occur when neural inspiratory time is longer than the inspiratory time set on the ventilator2.…”

“…It is important to realize that the first cycle delivered can be triggered by patient effort or the ventilator. Liao et al classified the double triggering in DT-P (double triggering where the patient triggers these first cycle), DT-A (double trigger where the first cycle is triggered byauto-triggering) and DT-V (when the first cycle is triggered by the ventilator according to the programmed criteria) [15]. The results in the same study showed that the DT-P is associated with short inspiratory time and that a correct programing of the inspiratory time decreases or even eliminate the presence of double triggering.…”

Patient-Ventilator Interaction During Noninvasive Ventilation in Simulated COPD

“…7 Furthermore, persistent inspiratory effort after pressure support ceases can lead to double-triggering, 7 resulting in discomfort, elevated tidal volumes (V T ), and volutrauma. 8 Cycling after the end of inspiratory effort shortens the expiratory time, causing intrinsic PEEP 9 and leading to increased work of breathing during triggering of the next breath. 10,11 SEE THE RELATED EDITORIAL ON PAGE 122 In former generations of ventilators, cycling criteria were fixed, usually to 25% of peak inspiratory flow.…”

“…10,11 SEE THE RELATED EDITORIAL ON PAGE 122 In former generations of ventilators, cycling criteria were fixed, usually to 25% of peak inspiratory flow. 8 Lack of synchronization is common with this setting. 4,5,[9][10][11] This problem is highlighted in patients with COPD 4,12 due to the long time constant.…”