Supplementary Material for: Colorimetric CO2 Detector to Improve Effective Mask Ventilations in Very Preterm Infants: A Pilot Randomized Controlled Study

Introduction: End tidal CO2 (ETCO2) detector is currently recommended for confirmation of endotracheal tube placement during neonatal resuscitation. Whether it is feasible to use ETCO2 detectors during mask ventilation to reduce risk of bradycardia and desaturations, which are associated with increased risk of death in preterm babies, is unknown. Methods : This is a pilot randomized controlled trial ((NCT04287907) involving newborns 24+0/7 to 32+0/7 weeks gestation who required mask ventilation at birth. Infants were randomized into groups with or without colorimetric ETCO2 detectors. Combined duration of any bradycardia (<100bpm) and time below prespecified target oxygen saturations (SpO2) as measured by pulse oximetry were compared. Results : Fifty participants were randomized, 47 with outcomes analysed (2 incomplete data, 1 postnatal diagnosis of trachea-esophageal fistula). Mean gestational age and birthweight were 28.5±1.9 vs 29.4±1.6 weeks, (p=0.1) and 1252.7±409.7g vs 1334.6±369.1g, (p=0.5) in the intervention and control arm respectively. Mean combined duration of bradycardia and desaturation was 276.7±197.7s (intervention) and 322.7±277.7s (control),(p=0.6). Proportion of participants with any bradycardia or desaturation at 5 minutes were 38.1% (intervention) and 56.5% (control), (p=0.2). No chest compressions, epinephrine administration or death occurred in the delivery room. Conclusion: This pilot study demonstrates that the feasibility of a trial to evaluate colorimetric ETCO2 detectors during mask ventilation of very preterm infants to reduce bradycardia and low SpO2. Further assessment with a larger population will be required to determine if ETCO2 detectors usage at resuscitation reduces risk of adverse outcomes, including death and disability, in very preterm infants.引言：目前推荐在新生儿复苏过程中使用呼气末二氧化碳（End tidal CO2, ETCO2）检测仪来确认气管导管的置入位置。在面罩通气期间使用ETCO2检测仪以降低心动过缓和血氧饱和度下降的风险——此类事件与早产儿死亡风险升高相关——是否可行，目前尚不明确。 方法：本研究为一项先导性随机对照试验（临床试验注册号：NCT04287907），纳入妊娠24+0/7周至32+0/7周、出生时需接受面罩通气的新生儿。将受试者随机分为使用比色ETCO2检测仪的干预组与未使用的对照组。比较两组的心动过缓（心率<100次/分）时长与脉搏血氧饱和度（SpO2）低于预设目标值的时长之和。 结果：共随机纳入50名受试者，最终对47名的结局进行分析（2例数据不全，1例产后确诊为气管食管瘘）。干预组与对照组的平均胎龄分别为28.5±1.9周与29.4±1.6周（p=0.1），平均出生体重分别为1252.7±409.7g与1334.6±369.1g（p=0.5）。干预组与对照组的心动过缓合并血氧饱和度下降的平均总时长分别为276.7±197.7秒与322.7±277.7秒（p=0.6）。出生5分钟时出现心动过缓或血氧饱和度下降的受试者占比，干预组为38.1%，对照组为56.5%（p=0.2）。产房内未实施胸外按压、未给予肾上腺素，亦无新生儿死亡病例。 结论：本先导性研究证实，针对极早产儿面罩通气期间使用比色ETCO2检测仪以降低心动过缓与低SpO2风险的试验具备可行性。后续需纳入更大样本量的人群开展评估，以明确复苏期间使用ETCO2检测仪是否可降低极早产儿包括死亡与残疾在内的不良结局风险。