Ventilator performances for non-invasive ventilation: a bench study

Abstract

Introduction: A wide range of recent ventilators, dedicated or not, is available for non-invasive ventilation (NIV) in respiratory or intensive care units (ICU). We conducted a bench study to compare their technical performances.

Methods: Ventilators, including five ICU ventilators with NIV mode on, two dedicated NIV ventilators and one transport ventilator, were evaluated on a test bench for NIV, consisting of a 3D manikin head connected to an ASL 5000 lung model via a non-vented mask. Ventilators were tested according to three simulated lung profiles (normal, obstructive, restrictive), three levels of simulated air leakage (0, 15, 30 L/min), two levels of pressure support (8, 14 cmH₂O) and two respiratory rates (15, 25 cycles/min).

Results: The global median Asynchrony Index (AI) was higher with ICU ventilators than with dedicated NIV ventilators (4% (0; 76) vs 0% (0; 15), respectively; p<0.05) and different between all ventilators (p<0.001). The AI was higher with ICU ventilators for the normal and restrictive profiles (p<0.01) and not different between ventilators for the obstructive profile. Auto-triggering represented 43% of all patient-ventilator asynchrony. Triggering delay, cycling delay, inspiratory pressure-time product, pressure rise time and pressure at mask were different between all ventilators (p<0.01). Dedicated NIV ventilators induced a lower pressure-time product than ICU and transport ventilators (p<0.01). There was no difference between ventilators for minute ventilation and peak flow.

Conclusion: Despite the integration of NIV algorithms, most recent ICU ventilators appear to be less efficient than dedicated NIV ventilators. Technical performances could change, however, according to the underlying respiratory disease and the level of air leakage.

Keywords: COPD Exacerbations; Critical Care; Equipment Evaluations; Non invasive ventilation.

Figure 1. Comparison of Asynchrony Index (AI) between ventilators. Values are aggregated across the three lung models and the two pressure support levels, and expressed as median (point) and interquartile interval (bars). *p<0.05, **p<0.01.

Figure 2. Comparison of Asynchrony Index (AI) between ventilator categories. Values are aggregated across the three lung models and the two pressure support levels, and expressed as median (point, square, triangle) interquartile interval (bars). *p<0.05.

Figure 3. Comparison of Asynchrony Index (AI) between ventilators. Values are aggregated across the two pressure support levels, and expressed as median (point) and interquartile interval (bars). *p<0.05, **p<0.01. (A) Restrictive ventilatory pattern. (B) Normal ventilatory pattern. (C) Obstructive ventilatory pattern.

Figure 4. Comparison of inspiratory pressure time product (PTPt) between ventilators. Values are aggregated across the three lung models and the two pressure support levels, and expressed as median (point) and interquartile interval (bars). *p<0.05, **p<0.01.