Automated Versus Manual Oxygen Control in Preterm Babies on Respiratory Support

Overview

Babies admitted in the NICU (neonatal intensive care unit) frequently need supplemental oxygen to keep their oxygen saturation (SpO2) in target range (TR). Hypoxia and hyperoxia episodes should be avoided while working toward this goal. Preterm babies are particularly vulnerable to abnormal oxygen levels, and adverse effects of hyperoxia and oxygen toxicity may result in retinopathy of prematurity and bronchopulmonary dysplasia. Similarly, mortality may rise due to hypoxic events. In routine practice, the SpO2 target is usually achieved by manual adjustment of FiO2 (fraction of inspired oxygen), but it usually does not accomplish the desired SpO2 target, leading to episodes of hyperoxia and hypoxia and increased risk of complications. A study was conducted in multiple centers involving extremely preterm babies, the results of which depicted that the babies on manual control of FiO2 spent only 48% of their time with SpO2 in the target range, 16% below the target range, and 36% above it. The compliance of the SpO2 target range was also variable in these centers. There is a need to improve compliance by using automated oxygen control systems. At the Aga Khan University Hospital (AKUH) investigators have included SLE 6000 (SLE, Croydon, UK) ventilators in their NICU (neonatal intensive care unit) which have automated oxygen control device "Oxygenie" that continuously adjusts FiO2 (fraction of inspired oxygen) of the patient to keep SpO2 in the target range, avoiding abnormal oxygen levels. This also reduces the workload on staff and improves patient care. Investigators usually put preterm babies on these ventilators so that SpO2 can be kept most of the time in the target range. When the OxyGenie and SpO2 monitoring are added to the SLE 6000 ventilator, it becomes possible to accurately regulate and deliver closed loop oxygen to preterm infants. This automated oxygen control system limits episodes of both hypoxia and hyperoxia by using the VDL 1.1 algorithm that uses an adaptive Proportional-Integral-Derivative (PID) algorithm to control the FiO2 adjustments in response to changes in SpO2. This keeps SpO2 within a target range (TR) which user selects. A randomized crossover trial comparing two devices for automated oxygen control in preterm infants included the SLE 6000 ventilator as one of its devices.

Investigators will conduct a radomized cross-over trial. 24 Preterm babies will be sampled, and to account for attrition, 26 preterm babies will be enrolled. Preterm babies born at less than 37 weeks of gestation will be included in the study. For each of the twelve-hour periods, they will be randomized to either manually controlled oxygen or automated oxygen control. After 12-hour periods, they will be shifted to alternate interventions. The total duration will be 24 hours. Written consent will be obtained from the parent/guardian before recruitment. Block randomization will be done to randomize the babies. SLE 6000 ventilators will be used, and settings will be adjusted by the clinical team as per the clinical condition of the baby. The Radical neonatal pulse oximeter (Masimo) is used to automatically adjust FiO2 in order to maintain SpO2 within a designated target range. Before turning on oxygen, FiO2 is manually adjusted to achieve SpO2 in the target range. Once stable SpO2 is achieved in TR, oxygen is turned on, which then adjusts FiO2 to keep SpO2 within target range. The FiO2 changes and their frequency are determined by the SpO2 trend, whether the SpO2 is above, below, or within the target range, and all changes are proportionate to the baseline FiO2 level. The pulse oximeter's settings will include normal sensitivity, an average time of 2-4 seconds, a 20-second alarm delay, and an alarm limit of 89% and 95% SpO2. Whenever feasible, the right wrist is used to apply the Masimo neonatal probe. The user will be advised on screen if the SpO2 signal will be lost. Oxygenie would display in blue, waiting for a signal, and would remain on the current FiO2 value for the first 60 seconds. After this point, if the SpO2 is within TR, it will continue at the current FiO2 level. If the SpO2 is above the TR and the FiO2 is 10% above the reference range, it will slowly decrease to the reference value. If SpO2 is below TR and FiO2 is more than 5% below the reference FiO2, then it will slowly increase to the reference level. The reference FiO2 value is updated every 30 minutes and is based on the last 60-minute average.