Abstract 1259 Poster Session I, Saturday, 5/1 (poster 38)

Studies have demonstrated the effectiveness of End Expiratory Pressure (EEP) in improving oxygenation in MAS (Pediatrics 1975;56:214-17, J Pediatr 1982;100:284-90). Yet there are concerns of its safety in terms of predisposing or exacerbating airleaks, and systemic hypotension. We have been using CPAP/EEP on IMV (Intermittent Mandatory Ventilation) of +5cm H2O in the management of MAS since 6/94. This retrospective study seeks to determine 1.incidence of airleaks and hypotension 2.oxygen dependency duration and survival till discharge, in these MAS infants. Method: Period of study:6/94 to 4/97. Only infants > 2kg birth weight were studied.MAS was diagnosed based on a history of meconium-stained liquor, respiratory distress, positive radiological features with or without positive endotracheal suctioning. These infants had delivery room resuscitation according to AAP guidelines. Infants were initially managed by nasal CPAP(Hudson) +5 cm H2O. IMV was indicated if PaO2 <50mmHg on 80% CPAP. On IMV, 'gentle ventilation' as described by Wung et al (Pediatrics 1985;76:488-94) was employed using a EEP of +5cm H2O. We aim to keep PaO2>50 mmHg/SaO2>87%. Airleaks were diagnosed by X-Ray and significant pneumothorax was evacuated by chest tube. Systemic hypotension was treated with saline (10-20 ml/kg) followed by inotropes (dopamine and dobutamine) if hypotension was persistent. Results: 62 consecutive infants were studied .48(77.4%) required only CPAP without IMV support. None of these 48 infants had significant airleak requiring chest tube. 14(22.6%) infants required IMV.4 of these 14 infants had airleaks requiring chest tube. The airleaks occurred whilst on high ventilatory pressures (max Peak Inspiratory Pressure:34.3+/-10.3(mean+/-SD), range:22-45 cm H2O). 11(17.7%) infants had hypotension requiring inotropic support (2 whilst on CPAP,9 whilst on IMV with concomitant PPHN). All infants survived.1 infant required home oxygen. Excluding this infant, oxygen dependency duration was 4.3+/-4.6(mean+/-SD)days. Conclusion: The majority (77%) of our MAS infants could maintain adequate oxygenation (PaO2>50mmHg) with CPAP+5cm H2O alone without IMV. This study suggests that the risk of significant airleak requiring chest tube is minimal whilst on CPAP. Significant airleaks may occur whilst on IMV especially whilst receiving high ventilatory pressures(4 of 14 infants in this study). Hypotension was mainly observed in infants with concomitant PPHN. We observed good survival rates (100%) using this strategy.