Analysis of peak inflating pressure and inflating pressure limit during neonatal volume guaranteed ventilation.

OBJECTIVES: To report how peak inflating pressure (PIP), tidal volume (VT) and low-tidal volume alarms are affected by maximum allowed inflating pressure (Pmax ) during volume guarantee (VG) ventilation.

STUDY DESIGN: Ventilation data were analysed with 1 Hz sampling rate from 25 neonates receiving synchronised intermittent positive pressure ventilation with VG for >12 h.

RESULTS: The difference between Pmax and PIP (Pdiff ) ranged between 5 and 20 mbar (median = 11 mbar) despite a protocol to keep Pmax 5 mbar above the "working PIP". Pmax was reached in 5.2% of inflations. Computational modelling demonstrated that had Pdiff been kept at 5 mbar more consistently, >10% of inflations would have reached Pmax . The frequency of low-tidal volume alarms showed inverse correlation with Pdiff .

CONCLUSIONS: It is difficult to implement a simple Pmax strategy due to variability of PIP. Setting Pmax close to the "working PIP" limits VT delivery and triggers frequent alarms.