Simma B, Skladal D, Falk M
Intensive Care Unit, Children's Hospital, Innsbruck, Austria.
Wien Klin Wochenschr. 2000 Sep 29;112(18):804-10.
This retrospective study identifies factors which may predict outcome in preterm infants and infants born at term, ventilated with high-frequency oscillation (HFO). In a 16-bed neonatal and paediatric intensive care unit (level III), 58 consecutive preterm and term infants with a median gestational age of 30 (24-41) weeks and a median birth weight of 1200 (520-3660) g suffered respiratory failure and were managed with HFO as rescue therapy. Forty-nine patients (84%) received exogenous surfactant before HFO which was initiated after a median interval of 20 (1-910) hours following birth. The overall survival rate was 70%. No significant differences existed between survivors and nonsurvivors in respect to demographic data. A greater proportion of patients with respiratory distress syndrome survived (76%) than with lung hypoplasia (20%) or with air-leak syndromes (pulmonary interstitial emphysema 60%, pneumothorax 28%). In survivors, the mean oxygenation index (OI) before HFO was significantly lower than that in nonsurvivors (16 +/- 1.3 vs. 26 +/- 3, p < 0.01) and showed a significant reduction of 32% within 4 hours. In contrast, mean OI increased to 68% over the first 4 hours in nonsurvivors and the difference between survivors and nonsurvivors remained significant during this time (after 2 hours: 15 +/- 1.5 vs. 30 +/- 6, p < 0.01; after 4 hours: 11 +/- 1 vs. 43 +/- 1, p < 0.01). A receiver of operator analysis revealed that an initial OI < 25 or alveolar-arterial oxygen difference (AaDO2) < 450 mmHg predicted survival with a sensitivity of 93% and a specificity of 41%. The positive predictive value was 79%; the negative predictive value, 70%.
A low OI and AaDO2 at the beginning of HFO, improvement in oxygenation over the first four hours of HFO ventilation and no development of air-leak syndromes were associated with a high predicted survival. This allows early identification of infants who may not survive and may benefit from established and alternative modes of respiratory support such as extracorporeal membrane oxygenation, nitric oxide and liquid ventilation.
