We compared the efficacy of a Drager Narkomed GS (North American Drager, Telford, PA) equipped with an adult circle system with two free-standing infant ventilator systems (Servo 300; Siemens Medical Systems, Danvers, MA and Babylog 8000; North American Drager) to deliver minute ventilation (V(E)) using pressure-limited ventilation to a test lung set to low compliance. To simulate a wide variety of potential patterns of ventilation, V(E) was measured 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; the average was used for data analysis using the multiple regression technique. Delivered V(E) was positively correlated with both PIP (P = 0.001) and RR (P = 0.001). Only minimal differences in V(E) were observed between the circle and the two free- standing systems. At lower RR and PIP, the Babylog 8000 system delivered slightly higher V(E) than the circle system, whereas at higher RR and PIP, the Babylog 8000 delivered slightly lower V(E) than the circle system; these differences in V(E) were not statistically significant (P = 0.45). The Servo 300 delivered slightly higher V(E) than the circle system in all test conditions, but these differences were not statistically significant (P = 0.09). None of the differences in delivered V(E) between the Servo 300 and the circle system are of clinical importance. Implications: Our laboratory investigation suggests that pressure-limited ventilation delivered by a standard adult circle system compares favorably with that of freestanding infant ventilators used in pressure-limited mode. Changing from an adult circle system to a free-standing pressure-limited ventilator may not substantially improve ventilation of a low-compliance infant lung; the efficacy of such a practice should be investigated.
ASJC Scopus subject areas
- Anesthesiology and Pain Medicine