Neonatal assisted ventilation: Predictors, frequency, and duration in a mature managed care organization

Objectives. Reference data are lacking on the frequency and duration of ass isted ventilation in neonates. This information is essential for determinin g resource needs and planning clinical trials. As mortality becomes uncommo n, ventilator utilization is increasingly used as a measure for assessing t herapeutic effect and quality of care in intensive care medicine. Valid com parisons require adjustments for differences in a patient's baseline risk f or assisted ventilation and prolonged ventilator support. The aims of this study were to determine the frequency and length of ventilation (LOV) in pr eterm and term infants and to develop models for predicting the need for as sisted ventilation and length of ventilator support. Methods. We performed a retrospective, population-based cohort study of 77 576 inborn live births at 6 Northern California hospitals with level 3 inte nsive care nurseries in a group-model managed care organization. The gestat ional age-specific frequency and duration of assisted ventilation among sur viving infants was determined. Multivariable regression was performed to de termine predictors for assisted ventilation and LOV. Results. Of 77 576 inborn live births in the study, 11 199 required admissi on to the neonatal intensive care unit and of these, 1928 survivors require d ventilator support. The proportion of infants requiring assisted ventilat ion and the median LOV decreased markedly with increasing gestational age. In addition to gestational age, admission illness severity, 5-minute Apgar scores, presence of anomalies, male sex, and white race were important pred ictors for the need for assisted ventilation. The ability of the models to predict need for ventilation was high, and significantly better than birth weight alone with an area under the receiver operating characteristic curve of .90 versus .70 for preterm infants, and .88 versus .50 for term infants . For preterm infants, gestational age, admission illness severity, oxygena tion index, anomalies, and small-for-gestational age status were significan t predictors for LOV, accounting for 60% of the variance in the length of a ssisted ventilation. For term infants, oxygenation index and anomalies were significant predictors but only accounted for 29% of the variance. Conclusions. Considerable variation exists in the utilization of ventilator support among infants of closely related gestational age. In addition, a n umber of medical risk factors influence the need for, and length of, assist ed ventilation. These models explain much of the variance in LOV among pret erm infants but explain substantially less among term infants.