An adult system versus a Bain system: comparative ability to deliver minute ventilation to an infant lung model with pressure-limited ventilation.

UNLABELLED

We compared the efficacy of an adult circle system versus a Bain system to deliver minute ventilation (V(E)) to an infant test lung model using pressure-limited ventilation. To simulate a wide variety of potential infant clinical states, V(E) was measured with two compliances: at peak inspiratory pressures (PIP) of 20, 30, 40, and 50 cm H2O and at respiratory rates (RR) of 20, 30, 40, and 50 breaths/min. Each measurement was made three times, and their average was used for analysis. Data were analyzed using the multiple regression technique. In both normal and low-compliance lung models, V(E) was nearly identical between adult circle and Bain systems (P = 0.67 for normal compliance model, P = 0.89 for low-compliance model). V(E) positively correlated with RR (P < 0.001), PIP (P < 0.001), and lung compliance (P < 0.001). Very high PIP or RR were required to deliver V(E) to the low-compliance lung model. The adult circle system is equivalent to the Bain system in its ability to ventilate an infant test lung over a wide range of RR, PIP, and two compliances during pressure-limited ventilation. V(E) is dependent of PIP, RR, and lung compliance. With low-compliance lungs, both systems require a high PIP. We conclude that both anesthetic systems deliver ventilation over a wide range of respiratory variables during pressure-limited ventilation in infants.

IMPLICATIONS

We obtained results from this infant test lung study that indicate that either an adult circle breathing system or the Bain system can reliably deliver ventilation over a wide range of respiratory variables during pressure-limited ventilation in infants.