BACKGROUND: Ventilators used for noninvasive ventilation (NIV) must be able to synchronize in the presence of system leaks. We compared the ability of 7 ICU ventilators and 3 dedicated NIV ventilators to compensate for leaks during pediatric NIV. METHODS: Using a lung simulator, we compared the Maquet Servo-i, Dräger V500, Dräger Carina, Covidien PB840, Respironics V60, Respironics Vision, GE Healthcare/Engström Carestation, CareFusion Avea, Hamilton C3, and Hamilton G5 during increasing (n ؍ 6) and decreasing leaks (n ؍ 6). With a lung simulator we tested 4 leak levels (baseline [BL] 2-3 L/min, L1 5-6 L/min, L2 9 -10 L/min, and L3 19 -20 L/min); 3 patient weights (10, 20, and 30 kg); and 3 lung mechanics scenarios (normal, obstructive, and restrictive). The ventilator settings were NIV mode, pressure support of 10 cm H 2 O, and PEEP of 5 cm H 2 O. The synchronization rate (synchronized cycles/total simulated respirations) was recorded for each ventilator and each leak scenario. Synchronization was defined as triggering without auto-triggering, miss-triggering, delayed cycling, or premature cycling. RESULTS: The mean synchronization rate across all ventilators was 68 ؎ 27% (range 23-96%) and marked differences existed between the ventilators (P < .001). Significant differences in synchronization rate were observed between the 10-kg model (mean 57 ؎ 30%, range 17-93%), the 20-kg model (69 ؎ 30%, 25-98%), and the 30-kg models (77 ؎ 22%, 28 -97%) (P < .001). The synchronization rate for the obstructive model (60 ؎ 30%, 9 -94%) was significantly different from the normal model (71 ؎ 29%, 18 -98%) and the restrictive model (72 ؎ 28%, 23-98%) (P < .001). The PB840 and the C3 had synchronization rates over 90% overall across all body weights, all lung mechanic profiles, and all leak levels. CONCLUSIONS: Leak compensation in NIV for pediatric use can partially compensate for leaks, but varies widely among ventilators, patient weights, and lung mechanics.