Factors affecting abnormal triggering with non-invasive ventilators: A before-and-after study

Introduction

Abnormal triggering of non‐invasive ventilator (NIV) is the main reason for increasing the possibility of patient intolerance and directly affecting the treatment effect.

Objective

To investigate factors that affect abnormal triggering of NIV.

Methods

Thirty health volunteers from August 2018 to August 2019 were recruited. Two kinds of NIVs, Curative Flexo ST30 and Resmed Stellar™ 150, were selected, with S/T mode, respiratory rate of 10 bpm and inspiration time of 1.0 s. Every volunteer received ventilation in two ventilators, five oxygen flows (5/10/15/20/25 L/min), five support pressures (independent inspired positive airway pressure/expired positive airway pressure [IPAP/EPAP]: 8/4; 10/4; 12/4; 16/6; 20/8 cm H₂O), two oxygen injection sites (proximal to the mask or the ventilator) and three masks (Curative: Bestfit™; Resmed: Mirage Quattro Full Face Mask™; Zhongshan: ZS‐MZ‐A™) for 60 min, respectively.

Results

All factors mentioned above affected normal triggering. With the increase of oxygen flow and support pressure, the frequency of auto‐triggering and ineffective‐triggering increased (P < 0.05). For Curative Flexo ST30 ventilator, when the oxygen injection site was proximal to the ventilator, the frequency of auto‐triggering and ineffective‐triggering is significantly lower than when it was proximal to the mask, whereas the result in Resmed Stellar™ 150 is totally different (P < 0.05).

Conclusion

When using Curative Flexo ST30 ventilator, the oxygen injection site should be proximal to the ventilator, whereas Resmed Stellar™ 150 ventilator is just the opposite. Attention should be paid to the effectiveness of ventilators when oxygen flow and support pressure settings are high, as abnormal triggers occur more frequently. Choosing the suitable mask is also important.

Cardiogenic Auto-Triggering as a Consequence of Hemoperitoneum

A 70-year-old woman presented with hemorrhagic shock secondary to hemoperitoneum following a paracentesis. On hospital day 3, she developed respiratory alkalosis and increased respiratory rates observed on the ventilator despite no spontaneous inspiratory effort. Converting to pressure support mode uncovered a cardiogenic oscillatory flow that had been auto-triggering the ventilator. This cardiogenic auto-triggering resolved with large-volume paracentesis. Cardiogenic auto-triggering leads to patient-ventilator dyssynchrony, respiratory alkalosis, lung distension, and difficulty with weaning from the ventilator, and it may be unrecognized in ICUs.