Multifrequency Oscillatory Ventilation in the Premature Lung: Effects on Gas Exchange, Mechanics, and Ventilation Distribution

• Published in: Anesthesiology (Philadelphia) 2015-12, Vol.123 (6), p.1394-1403
• Main Authors: Kaczka, David W, Herrmann, Jacob, Zonneveld, C Elroy, Tingay, David G, Lavizzari, Anna, Noble, Peter B, Pillow, J Jane
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Animals; Animals, Newborn; Blood Gas Analysis - statistics & numerical data; Cross-Over Studies; Electric Impedance; High-Frequency Ventilation - methods; Lung - physiopathology; Respiration; Respiratory Insufficiency - prevention & control; Respiratory Mechanics - physiology; Sheep; Treatment Outcome
• ISSN: 1528-1175
• DOI: 10.1097/ALN.0000000000000898

Despite the theoretical benefits of high-frequency oscillatory ventilation (HFOV) in preterm infants, systematic reviews of randomized clinical trials do not confirm improved outcomes. The authors hypothesized that oscillating a premature lung with multiple frequencies simultaneously would improve gas exchange compared with traditional single-frequency oscillatory ventilation (SFOV). The goal of this study was to develop a novel method for HFOV, termed "multifrequency oscillatory ventilation" (MFOV), which relies on a broadband flow waveform more suitable for the heterogeneous mechanics of the immature lung. Thirteen intubated preterm lambs were randomly assigned to either SFOV or MFOV for 1 h, followed by crossover to the alternative regimen for 1 h. The SFOV waveform consisted of a pure sinusoidal flow at 5 Hz, whereas the customized MFOV waveform consisted of a 5-Hz fundamental with additional energy at 10 and 15 Hz. Per standardized protocol, mean pressure at airway opening ((Equation is included in full-text article.)) and inspired oxygen fraction were adjusted as needed, and root mean square of the delivered oscillatory volume waveform (Vrms) was adjusted at 15-min intervals. A ventilatory cost function for SFOV and MFOV was defined as (Equation is included in full-text article.), where Wt denotes body weight. Averaged over all time points, MFOV resulted in significantly lower VC (246.9 ± 6.0 vs. 363.5 ± 15.9 ml mmHg kg) and (Equation is included in full-text article.)(12.8 ± 0.3 vs. 14.1 ± 0.5 cm H2O) compared with SFOV, suggesting more efficient gas exchange and enhanced lung recruitment at lower mean airway pressures. Oscillation with simultaneous multiple frequencies may be a more efficient ventilator modality in premature lungs compared with traditional single-frequency HFOV.