PREDICTORS OF FAILURE OF HIGH-FREQUENCY OSCILLATORY VENTILATION IN TERM INFANTS WITH SEVERE RESPIRATORY-FAILURE

Objective. To identify clinical factors in term neonates with severe r espiratory failure that predict which neonates are unlikely to respond to high-frequency oscillatory ventilation (HFOV). Design. This was a retrospective review of patient charts and medical records.Patients. W e studied 190 newborns treated with HFOV between July 1985 and Decembe r 1992. All patients were at least 35 weeks' estimated gestational age and had severe respiratory failure, defined as arterial to alveolar o xygen ratio (a/A ratio) of less than 0.2 or the need for peak inspirat ory pressure greater than 35 cm H2O on conventional ventilation. Resul ts. Of the 190 patients, 111 (58%) responded to HFOV (HFOV responders) , and 79 (42%) were placed on extracorporeal membrane oxygenation (ECM O) after HFOV failed to improve gas exchange (nonresponders). The two groups were similar in gender and birth weight. Factors associated wit h failure of HFOV to produce a sustained improvement in gas exchange w ere a diagnosis of congenital diaphragmatic hernia and more severe res piratory compromise as assessed by admission blood gas. Stepwise logis tic regression analysis showed that a diagnosis of congenital diaphrag matic hernia/lung hypoplasia (CDH/LH) and the a/A ratio at initiation of and after 6 hours of HFOV were the only significant independent pre dictors of the need for ECMO. Among all the patients, the presence of CDH/LH or an initial a/A ratio of 0.05 or lower yielded a sensitivity of 74% and specificity of 77% in correctly identifying neonates in who m HFOV failed to produce a sustained improvement in oxygenation. When neonates with CDH/LH were excluded from analysis, the most significant predictor of failure of HFOV was the a/A ratio after 6 hours of HFOV. In neonates without CHD/LH, a 6-hour a/A ratio of 0.08 or lower discr iminated responders from nonresponders tie, treatment with ECMO) with a sensitivity of 77% and specificity of 92%. Conclusions. In our patie nts, the presence of CDH/LH, severe respiratory failure (a/A ratio 0.0 5 or lower) at initiation of HFOV, and lack of improvement in oxygenat ion (a/A ratio 0.08 or lower after 6 hours of HFOV) were associated wi th failure of HFOV and treatment with ECMO. This information should he lp other centers to identify neonates who are at the greatest risk for requiring ECMO support and thus allow prompt transfer to an ECMO cent er.