Automatic Oxygen Control for Reducing Extremes of Oxygen Saturation (AreOS): A Randomised Control Trial

Overview

Oxygen treatment is common in babies born early (preterm) and requiring intensive care. Having too much or too little oxygen can increase the risk of damage to the eyes and lungs, and contribute to death or disability. Preterm infants because of their immaturity experience episodes of low oxygen levels. The low oxygen episodes are primarily due to pauses in their breathing (Apnoea of prematurity) and immaturity of their lung. These episodes persist for weeks. The lower the gestation at birth the longer the duration of these events. Studies have shown that these episodes of low oxygen saturations especially if frequent and prolonged is associated with poor developmental outcome, severe eye disease and lung disease. Traditionally, the oxygen delivery is manually adjusted when infant has low oxygen saturation. However previous studies have shown despite the best efforts the oxygen level can only be maintained less than half of the time and nearly a one-fifth of the time infant spends in low oxygen levels and nearly one third of the time in high oxygen levels. Now it is possible to maintain oxygen level in target range by using automatic control of oxygen delivery. With the proposed study, we would like to study the efficacy of automatic control of oxygen delivery in reducing the time spent in low oxygen levels.

Supplemental oxygen remains by far the most commonly used 'drug' in neonatal intensive care units. The goal of oxygen therapy is to maintain normal oxygenation while minimizing hypoxemia and hypoxemia. Preterm infants are particularly vulnerable to oxygen toxicity and oxidative stress leading to retinopathy of prematurity (ROP), bronchopulmonary dysplasia (BPD), and periventricular leukomalacia (PVL)\[1\]. It's also well known that preterm infants experience hypoxic events which are primarily linked to cardiovascular instability and apnea of prematurity. These events vary as the infant matures. Martin R et al showed in their study that these hypoxic events peaked around 2-4 weeks and decreases by 6-8 weeks in preterm infants (2). Exposure to prolonged and frequent hypoxemic episodes has been associated with increased morbidity and mortality \[3-5\]. Prolonged hypoxic events (Saturation less than 80% for more than 1 minute) have been associated with severe ROP and impaired neurodevelopmental outcome in survivors (2, 5). Peripheral oxygen saturation monitoring is standard of care in preterm infants. Traditionally oxygen saturation (SpO2) targeting is carried out by manual adjustment of fraction of inspired oxygen (FiO2) by the caregiver based on the monitored oxygen saturation. However, in practice this is only partially achieved during routine care\[6\]. Hagadorn et al conducted a study in 14 centers and showed that preterm infants under 28 weeks' gestation receiving oxygen spent on average only 48% of the time with SpO2 within the prescribed target range, about 36% of the time above and 16% of the time with SpO2 below the target range \[7\]. Preterm infants have frequent fluctuations in SpO2 due to their cardio-respiratory instability requiring frequent adjustments of FiO2 \[7\]. Consequently, these particularly vulnerable infants spend significant time with SpO2 outside intended range and are often exposed to extremes of hypoxemia and hyperoxaemia. It is now possible to have automated control of inspired oxygen using a device (CLiO2™) incorporated in Avea® ventilator. The device continuously monitors the oxygen saturation and adjusts the oxygen delivery to maintain oxygen saturation within the target range. The safety, feasibility and efficacy of this device have already been established \[9-14\]. There has been further improvement in the algorithm of the pulse oximeter incorporated in Avea® ventilator to achieve a better normative distribution around the median SpO2 value\[15\]. Automated control of FiO2 significantly improves compliance of oxygen saturation targeting and significantly reduces exposure to hypoxemia as well as hyperoxaemia \[9-14, 16,\]. Automatic control of oxygen delivery is available in both invasive and non-invasive mode of ventilation (17). The Avea ventilators are equipped with Automatic Oxygen control with invasive as well as non-invasive mode of ventilation. Previous studies looking at the efficacy of automated oxygen control mostly have been a crossover model and the study duration less than 48 hours. As previously mentioned, preterm infants experience hypoxic events for few weeks before cardiopulmonary maturation is established. Hence, it's important to study these events over a longer period of time. The objective of this randomised controlled trial is to evaluate the efficacy of the automatic oxygen control function in reducing the time spent in extremes of oxygen saturations (less than 80%), in preterm infants for the entire period of their respiratory support on invasive or non-invasive mode of ventilation.