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HFOV Versus CV for RDS
Prospective Randomized Multicenter Comparison of High Frequency Oscillatory Ventilation and Conventional Ventilation in Preterm Infants Less Than 30 Weeks With Respiratory Distress Syndrome. Moriette G, Paris-Llado J, Walti H, et al. Pediatrics 2001; 107 : 363 – 72.
273 preterm infants, 24-29 weeks gestation, with RDS were randomly assigned to receive high-frequency oscillatory ventilation (HFOV) or conventional ventilation (CV). There was no significant differences between groups with respect to EGA, birth weight, or age at enrollment. HFOV compared with CV was associated with a 2-fold reduction in the requirement for > 1 dose of surfactant (30% vs 62%; odds ratio = 0.27; 95% CI = .16 - .44). There was no significant difference in pulmonary outcome (O2 need at 36 weeks PMA). The incidence of severe IVH was 24% in the HFOV group and 14% in the CV group (adjusted odds ratio = 1.5; 95% CI 0.68-3.3).
Comment. The first multicenter trial of HFOV for HMD was by the HIFI Study Group in 1989. That study was terminated early due to concerns of an increased incidence of severe IVH in the HFOV group. Critics have maintained that the failure of HFOV in that study was due to the low lung volume strategy employed. At least 2 randomized controlled trails (by Clark in 1992, and Gerstmann in 1996) using the Sensormedics 3100 HFOV with a lung volume recruitment strategy, have shown increased survival without CLD with HFOV, and no difference in the incidence of severe IVH. Now the present study further confuses the issue by failing to demonstrate improved respiratory outcome using HFOV with a lung volume recruitment strategy, and renewed concerns about the possibility of more babies with severe IVH with HFOV treatment. The discrepancies in the results between these studies may be more technical than real. First of all, the studies are not directly comparable. The HFOV device used in the present trial (called OHF1) differs from the Sensormedics 3100 in that the OHF1 uses a fixed I/E ratio of 1:1. This could contribute to air trapping, which may result in cerebral venous congestion. Furthermore, after correcting for confounding variables, the improvement in pulmonary outcome in the HFOV group nearly reached statistical significance. It should also be noted that, after correcting for confounding variables, the differences in severe IVH between groups in the present study was not even close to achieving statistical significance. I guess the debate about the potential risks and benefits of prophylactic use of HFOV for RDS will continue