Prediction of prolonged ventilator dependence in preterm infants Abstract Volutrauma is an important factor in the pathogenesis of bronchopulmonary dysplasia (BPD). Our aims were to identify risk factors in the first 24 h for prolonged ventilator dependence and assess volume delivery and carbon dioxide levels in infants with evolving BPD. A retrospective study was undertaken of 41 infants born at less than 32 weeks of gestational age (GA). A higher tidal volume, minute volume and resistance and a lower GA, birth weight and compliance were associated with a significantly higher risk of ventilator dependence at 28 days. The strongest relationships were with birth weight (area under the receiver operating characteristic curve, AUROC = 0.771) and GA (AUROC = 0.813). Tidal volume remained significantly higher after adjusting for GA in those who remained ventilator dependent at 28 days. The 18 who remained ventilator dependent at 28 days had increased mean carbon dioxide (PCO2) levels with increasing age from a mean of 41 mmHg in the first 24 h to 65 mmHg at 28 days PMA (p < 0.001). The increase in PCO2 occurred despite increases in peak inflation pressures (p < 0.001), tidal volumes (p = 0.002) and minute volumes (p < 0.001). Conclusion: These results suggest that initial volutrauma may contribute to the development of chronic ventilator dependence. What is Known: • In prematurely born infants, excessive tidal volumes are important in the pathogenesis of bronchopulmonary dysplasia (BPD), but a tidal volume that is too low will increase the risk of atelectasis, work of breathing and energy expenditure. What is New: • A high tidal volume in the first 24 h was associated with an increased risk of ventilator dependence at 28 days, which remained significant after adjusting for gestational age. Carbon dioxide levels significantly increased over the first month despite increased pressures and volumes in those who remained ventilator dependent.