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


METHODS
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.


RESULTS
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.


CONCLUSIONS
Oscillation with simultaneous multiple frequencies may be a more efficient ventilator modality in premature lungs compared with traditional single-frequency HFOV.
From the Departments of Anesthesia, Biomedical Engineering, and Radiology (D.W.K.) and Department of Biomedical Engineering (J.H.), University of Iowa, Iowa City, Iowa; Neonatal Research, Murdoch Childrens Research Group, Melbourne, Victoria, Australia (C.E.Z.); Department of Paediatrics, University of Melbourne, and Neonatal Research, Murdoch Childrens Research Institute, and Department of Neonatology, Royal Children's Hospital, Melbourne, Victoria, Australia (D.G.T.); Neonatal Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia, and NICU, Fondazione IRCCS Ca'Granda, Ospedale Maggiore Policlinico Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy (A.L.); School of Anatomy, Physiology, and Human Biology, and Centre for Neonatal Research and Education, School of Paediatrics and Child Health, University of Western Australia, Perth, Western Australia, Australia (P.B.N.); and School of Anatomy, Physiology, and Human Biology and Centre for Neonatal Research and Education, School of Paediatrics and Child Health, University of Western Australia, and Neonatal Clinical Care Unit, Women and Newborn Health Service, Perth, Western Australia, Australia (J.J.P.).
David W
DW
Kaczka
Jacob
J
Herrmann
C Elroy
CE
Zonneveld
David G
DG
Tingay
Anna
A
Lavizzari
Peter B
PB
Noble
J Jane
JJ
Pillow
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001784:Blood Gas Analysis / Q000706:statistics & numerical data; D018592:Cross-Over Studies; D017097:Electric Impedance; D006612:High-Frequency Ventilation / Q000379:methods*; D008168:Lung / Q000503:physiopathology*; D012119:Respiration; D012131:Respiratory Insufficiency / Q000517:prevention & control*; D015656:Respiratory Mechanics / Q000502:physiology; D012756:Sheep; D016896:Treatment Outcome