Lower back-up rates improve ventilator triggering during assist-control ventilation: a randomized crossover trial

Objective:the objective of this study is to compare the effects of back-up ventilation rates (burs) on triggered inflations and patient cardiorespiratory stability during assist-control/volume guarantee ventilation (ac/vg).study design:this study is a randomized crossover trial conducted in a neonatal unit in an australian tertiary nicu. in all, 26 stable preterm infants on ac/vg ventilation were studied at bur settings of 30, 40 and 50 min−1. inflation rate, triggering and cardiorespiratory measures of patient stability were compared during 20 min epochs with 10 min washout periods.result:the 26 infants studied were median (inter-quartile range) gestational age 27 (26, 30) weeks, birth weight 0.84 (0.75, 1.14) kg and fio2 0.24 (0.21, 0.31) and age 6 (4, 19) days. at burs of 30, 40 and 50, the proportions of inflations, which were triggered, were mean (s.d.) 85% (11), 75% (19) and 61% (25); p<0.01 for all comparisons. total delivered inflation rates were 56 (8), 58 (9) and 62 (8) min−1, respectively. cardiorespiratory parameters did not vary between the settings.conclusion:using a lower bur allows greater triggering of ventilator inflations. cardiorespiratory parameters including co2 levels were stable at all rates.