Delivering Low Tidal Volume With Anesthesia and ICU Ventilators in a Neonatal Lung Model

Background: Mechanical ventilation of the neonate requires ventilators than can deliver precise and accurate tidal volume (V_T) and PEEP to avoid lung injury. Due to small neonatal V_T and the disproportionate effect of endotracheal tube leak in these patients, accomplishing precise and accurate V_T delivery is difficult. Whereas neonatal ICU ventilators are validated in this population, thorough studies testing the performance of anesthesia ventilators in delivering small V_T in neonates are lacking.

Methods: Three anesthesia ventilators, Dräger Apollo, GE Avance, and Getinge Flow-i; and 2 ICU ventilators, Medtronic PB980 and Nihon Kohden NKV-550, were tested under volume control mode at V_T of 5, 20, 40, and 60 mL. Three combinations of lung compliance and airway resistance were tested using a Servo ASL 5000 lung simulator.

Results: In a scenario without leak, the measured V_T was greater than the set V_T by > 10% in the Apollo (21.0% [18.8-26.0]); measured V_T was less than the set V_T by > 10% in the Flow-i (-19% [-20.8 to -18.7]). The Avance, PB980, and NKV-550 presented a volume error < 10% (-9.50% [-10.8 to -4.4], -5.8% [-11.8 to -3.5], and 5.4% [-4.5 to 18.9], respectively). Considering all combinations of set V_T, leaks, and respiratory mechanics, none of the anesthesia ventilators were able to deliver a median measured V_T within a 10% error. The bias between measured V_T and set V_T varied widely among ventilators (from 4.27 mL to -10.59 mL). Additionally, in the Apollo ventilator, PEEP was underdelivered with the largest leak value.

Conclusions: Our results suggest that in comparison with the 2 neonatal ICU ventilators tested, the anesthesia ventilators did not greatly differ in terms of V_T delivery in the presence of a gas leak.