Table 1.

Methods of inspiratory assist titration in NAVA and PAV+ and their pros and cons

Method	Pros	Cons
NAVA preview
Pawpeak matching	Intuitive and straightforward Implemented in the ventilator Helpful for detecting asynchronies in PSV mode	Pawpeak matching does not guarantee similar assist levels due to differences in Paw profile Depends on quality of initial PSV titration Breath-by-breath variability in EAdi amplitude may make matching difficult Does not consider variation in EAdi caused by the change from PSV to NAVA
Pawmean matching	Same pros as above Results in more similar assist levels between PSV and NAVA	Depends on quality of initial PSV titration Breath-by-breath variability in EAdi amplitude may make matching difficult Does not consider potential variation in EAdi caused by the change from PSV to NAVA
Ventilation matching	Simple	Depends on quality of initial PSV titration One cannot control ventilation with NAVA Does not incorporate the EAdi signal
NAVA titration based on patient’s response
Two-phased response of Paw and VT	Physiologically sound Reflects changes in respiratory muscle output Shown to result in a more personalized level compared to using NAVA preview	May be difficult to perform at the bedside, especially when considering the curvilinear relationship between EAdi and respiratory muscle effort depending on the level of assist Achieving a two-phased response in patients with very high respiratory drive and/or an overwhelmed Hering–Breuer reflex can be difficult
60% of EAdimaxSBT	Physiologically sound Provides daily re-assessment of the NAVA level and EAdi. Can theoretically be applied during any assisted ventilation mode	Limited to the use during after a failed PS 7/PEEP 0 cmH2O SBT EAdimaxSBT may be different according to the SBT method (i.e., T-piece or CPAP trial) Does not take into account accessory respiratory muscles that are often recruited during SBT failure 60% target is arbitrarily chosen; this may result in high inspiratory efforts in patients with high respiratory drive
Unloading based on NVE	Physiologically sound Easy to perform at the bedside Recommended to use 40% unloading target	Limited to the weaning phase NVE reflects ventilatory efficiency and not directly breathing effort A zero-assist breath is not fully unassisted, as the ventilator always provides a minimum level of inspiratory pressure (2-3 cmH2O) that slightly overestimates NVE
PAV+ titration
Pawmean matching	Simple and intuitive	Depends on quality of initial PSV titration Paw matching does not guarantee similar assist levels due to differences in Paw profile
Inspiratory effort (Pmus, PTPmus)	Physiologically sound Grid incorporated in the ventilator	Target values may be difficult to achieve in patients with excessive respiratory drive

EAdi diaphragm electrical activity, EAdi_maxSBT maximum EAdi amplitude during a spontaneous breathing trial (SBT), CPAP continuous positive airway pressure, NAVA neurally adjusted ventilatory assist, NVE neuroventilatory efficiency index, Paw airway pressure, PEEP positive end-expiratory pressure, Pmus muscular pressure, PTP pressure–time product, PS pressure support, PSV pressure support ventilation, V_T tidal volume