Evaluation of performance of two high-frequency oscillatory ventilators using a model lung with a position sensor

Abstract

Purpose: High-frequency oscillatory ventilation (HFOV) is thought to protect the lungs of acute respiratory distress syndrome (ARDS) patients. The performance and mechanical characteristics of high-frequency oscillatory ventilators, especially with regard to delivering appropriate tidal volume (V T) to compromised lungs, might affect the outcome of patients. We evaluated the performance of two such ventilators using a model lung with a position sensor. Methods: We tested the Metran R100 and SensorMedics 3100B. V T was measured using the model lung with the compliance set at 20 or 50 ml/cmH2O and the resistance at 0 or 20 cmH2O/l/s. Oscillator frequency was set at 5, 7, and 9 Hz, and amplitude was set at 25%, 50%, 75%, and 100% (100% being maximum amplitude available at each setting configuration). Results: At each model lung setting, R100 delivered greater V T at 5 Hz. V T differences between the ventilators decreased as frequency increased and were negligible at 9 Hz. At each model lung setting and frequency, as amplitude increased from 25% to 100%, V T increased proportionally more with R100. With an I:E ratio of 1:1, 3100B delivered greater V T than with 1:2. Conclusion: Because it is able to deliver comparably greater V T, R100 may be a better choice for HFOV in critical ARDS patients. Better proportionality may be a result of more effective amplitude titration for adjusting PaCO2 during oscillation. © 2010 Japanese Society of Anesthesiologists.