PREDICTING OUTCOME IN CHILDREN WITH SEVERE ACUTE RESPIRATORY-FAILURE TREATED WITH HIGH-FREQUENCY VENTILATION

Objectives: a) To demonstrate the effect of high-frequency ventilation on gas exchange in children with severe acute respiratory failure unr esponsive to conventional ventilation; b) to identify patients at high risk of death early after institution of high-frequency ventilation. Setting: Tertiary care pediatric intensive care unit in a university h ospital.Design: A cross-sectional, observational study with factorial design. Patients: Thirty-one patients with severe acute respiratory fa ilure defined as a PaO2/FIO2 of <150 torr (<20 kPa) with a positive en d-expiratory pressure of greater than or equal to 8 cm H2O and/or PaCO 2 of >60 torr (>8 kPa) with an arterial pH <7.25. Interventions: Patie nts received either high-frequency oscillation or jet ventilation if r espiratory failure was unresponsive to conventional ventilation and if the underlying disease process was deemed reversible. Measurements an d Main Results: Thirty one children were managed with high-frequency v entilation, 11 children with jet and 20 children with oscillator, Arte rial blood gases and level of ventilatory support were recorded before and at 6, 24, 48, 72, and 96 hrs after institution of high-frequency ventilation. There was an improvement in an arterial pH. PaCO2, PaO2/F IO2, and PaO2/FIO2, 6 hrs after institution of high-frequency ventilat ion (p < .01). This improvement, along with decreased need for oxygen, was sustained through the subsequent course, Twenty three (74%) of 31 children treated with high-frequency ventilation survived, Survivors showed an increase in an arterial pH, PaO2, PaO2/FIO2, and a decrease in PaCO2 within 6 hrs, whereas nonsurvivors did not, Oxygenation index was the best predictor of outcome. A combination of an initial oxygen ation index of >20 and failure to decrease the oxygenation index by >2 0% by 6 hrs after initiation of high-frequency ventilation predicted d eath with 88% (7/8) sensitivity and 83% (19/23) specificity, with an o dds ratio of 33 (p = .0036, 95% confidence interval 3-365). Conclusion s: In patients with potentially reversible underlying diseases resulti ng in severe acute respiratory failure that is unresponsive to convent ional ventilation, high-frequency ventilation improves gas exchange in a rapid and sustained fashion. The magnitude of impaired oxygenation and its improvement after high-frequency ventilation can predict outco me within 6 hrs.