Adaptive support ventilation prevents ventilator-induced diaphragmatic dysfunction: an in vivo piglet study

Introduction

Mechanical ventilation is a lifesaving supportive therapy for patients with acute respiratory failure. However, prolonged mechanical ventilation results in the complete absence of neural activation and mechanical activity of the diaphragm and has been shown to induce ventilator-induced diaphragmatic dysfunction (VIDD) [1]. Few studies have shown that maintaining spontaneous ventilation could prevent VIDD in in vitro animal studies [2]. Adaptive support ventilation (ASV) is an automatic ventilation mode that allowed pressure-controlled breaths in active patients able to trigger. The aim of our study was to compare ASV with controlled ventilation (CV) without paralysing agents on diaphragmatic contractile properties in an in vivo piglet study.

Methods

Two groups of six anesthetized piglets were ventilated during a 72-hour period. Piglets in the CV group (n = 6) were ventilated without any spontaneous ventilation and piglets in the ASV group (n = 6) were ventilated with the possibility of triggering spontaneous ventilation. The main endpoint was the transdiaphragmatic pressure (Pdi) (after bilateral, supramaximal, transjugular stimulation of the two phrenic nerves), which represents the in vivo contractile function of the diaphragm. A force-frequency curve was drawn after stimulation from 20 to 120 Hz of the phrenic nerves.

Results

The piglets in the ASV group were maintained with spontaneous ventilation during 80% of the study period instead of less than 1% in the CV group. At 72 hours, Pdi was decreased by 35% in the CV group although it was not modified in the ASV group (Figure 1).

Figure 1

Pdi evolution during the study. P < 0.05 CV vs. ASV group at 48 hours.

Conclusion

Spontaneous breathing with ASV prevents VIDD in comparison with totally CV in an in vivo healthy piglet model.