Neurally adjusted ventilatory assistance in patients with critical illness polyneuromyopathy

Introduction

Neurally adjusted ventilatory assistance (NAVA) delivers pressure (Paw) in proportion to the electrical activity of the diaphragm (EAdi). It is not known whether EAdi adequately reflects the respiratory drive in patients with critical illness polyneuromyopathy (CIPM) and would be sufficient to deliver assistance using NAVA.

Methods

Fifteen invasively ventilated patients (median (quartiles): 66 (59; 73) years old, APACHE II score 19 (17; 24)) with electrophysiologically documented CIPM were studied. A level of adequate unloading (NAVA_AL) was identified daily based on the characteristic response in Paw and tidal volume (Vt) to stepwise increasing NAVA (titration) as previously described [1]. NAVA_AL was used for a maximum of 72 hours.

Results

NAVA_AL was implemented in 13 patients for 54 (40; 61) hours. Three patients were liberated from mechanical ventilation during the study. NAVA could not be used in two patients (diaphragm myoclonic; excessive respiratory drive). At NAVA_AL peak inspiratory EAdi was reduced by 30 (25; 40)% compared with the lowest NAVA level used during the titration. The breathing pattern, heart rate, and mean arterial pressure remained stable during NAVA. See Table 1.

Table 1

Conclusion

EAdi was sufficient to use NAVA in most of our patients with moderate to severe CIPM. Implementation of a titrated NAVA level for up to 72 hours resulted in low Vt, improved oxygenation over time, and stable cardiorespiratory function.