A clinical audit on maintenance of optimal peripheral oxygen saturation in preterm neonates needing mechanical ventilation at a level III neonatal intensive care unit

Abstract

Introduction: With increasing survival of preterm neonates, oxygen therapy has become an integral part of neonatal respiratory support. In Sri Lanka survival rate of extremely preterm babies is nearly 70%. Most recent studies show oxygen saturations (SpO2) of 91-95% in preterm neonates maximize survival while minimizing side effects such as retinopathy of prematurity. Oxygenation can be optimized by controlling ventilator settings-i.e. fraction of inspired oxygen (FiO2), inspiratory time and mean airway pressure. Objective: To study the SpO2 trend maintained in ventilated (both invasive and non-invasive) preterm babies at the neonatal intensive care unit of Sri Jayewardenepura General Hospital. Method: Study was done in March 2018 on ventilated preterm babies <34 weeks gestation and birth weight <1.5kg. Neonates with pulmonary hypertension, bronchopulmonary dysplasia, cyanotic heart disease, major congenital anomalies and neonates on palliative care were excluded. SpO2 trend and related ventilator settings i.e. FiO2, peak inspiratory pressure / pressure support, and positive end expiratory pressure, were recorded daily at 8am and 2pm. SpO2 trend was observed for 10 minutes and the most persisting value taken to minimize observation bias. Data were analysed using SPSS 20. Results: Ten preterm neonates with 211 observations were studied. Maturity ranged from 27-33 weeks. Mean birth weight was 1.24 kg (SD=0.43) and 5 (50%) babies were extremely low birth weight. In 158 (74.9%) observations, SpO2 was >95%. Optimal SpO2 was noted only in 52/211 (24.6%) observations. In observations with SpO2 >95% where invasive ventilation was used, 35/120 (29.1%) had minimum ventilator settings i.e. PiP-14H2Ocm and FiO2-21%. Among babies with noninvasive modes, 68.4% of observations had a FiO2 of 21% with a PEEP of 5. Therefore, in 59.5% there was no room to reduce FiO2 further and in 29.1% of the instances with invasive ventilation there was no room for reducing ventilator settings. SpO2 was <89% only on 1 occasion. Conclusions: Even though in most of the instances minimum ventilator settings were used still there was room for further reduction.