Oh Sheow Boon, Aguilan Apollo, Tan Herng Lee, Ma Yi-Jyun, Sultana Rehena, Lee Jan Hau, Wong Judith Ju Ming
Lee Kong Chian School of Medicine, Singapore, Singapore.
Children's Intensive Care Unit, Department of Pediatric Subspecialties, KK Women's and Children's Hospital, Singapore, Singapore.
Front Pediatr. 2022 Feb 28;10:814484. doi: 10.3389/fped.2022.814484. eCollection 2022.
Alveolar dead-space fraction (AVDSF), the volume of alveolar gas that does not participate in gas exchange, has been reported to predict mortality and morbidity in adults with acute respiratory distress syndrome (ARDS). This study aims to characterize AVDSF in patients with pediatric ARDS (PARDS), to determine its association with clinical outcomes and examine the validity of a previously studied cutoff (AVDSF > 0.25).
This was a prospective cohort study performed in the setting of a lung protective mechanical ventilation protocol. AVDSF was calculated by the equation: AVDSF = [partial pressure of arterial carbon dioxide (PCO) - end tidal carbon dioxide (etCO)]/PCO. Receiver operating curve and Youden index were used to identify an AVDSF cutoff associated with mortality, which characterized "high or low AVDSF" groups. Correlation between AVDSF and clinical indices of severity were determined [including daily oxygenation index (OI), admission Pediatric Index of Mortality 2 (PIM 2) and Pediatric Logistic Organ Dysfunction (PELOD) scores]. The primary outcome, mortality in PARDS patients, was compared between the high and low AVDSF groups and analyzed in a multivariable logistic regression adjusting for inotrope use and PIM 2 score. Secondary outcomes included 28-day ventilator-free (VFD) and intensive care unit-free (IFD) days.
Sixty-nine PARDS patients with a median (interquartile range) age of 4.5 (0.8, 10.6) years were included in this analysis. Daily AVDSF correlated with daily OI ( = 0.10; < 0.001). Mean AVDSF over the first 7 days of PARDS correlated with PIM 2 ( = 0.10; = 0.010) and PELOD ( = 0.12; = 0.004) scores. The greatest area under the curve identified an AVDSF cutoff of 0.22, which was close to the previously suggested 0.25. The high AVDSF group had higher mortality [7/19 (36.8%) vs. 5/50 (10.0%); = 0.009] and lower VFD [2 (0, 18) vs. 21 (15, 24); = 0.007] and IFD [0 (0, 16) vs. 16 (5, 21); = 0.013]. In the multivariable model, being in the high AVDSF group [adjusted odds ratio 4.67 (95% CI: 1.12, 19.39)] was significantly associated with mortality.
High AVDSF was independently associated with increased mortality and decreased VFD and IFD. AVDSF may be complementary to oxygenation indices in risk stratifying PARDS and warrant further study.
肺泡死腔分数（AVDSF），即不参与气体交换的肺泡气体体积，据报道可预测成人急性呼吸窘迫综合征（ARDS）的死亡率和发病率。本研究旨在描述儿童急性呼吸窘迫综合征（PARDS）患者的AVDSF特征，确定其与临床结局的关联，并检验先前研究的临界值（AVDSF>0.25）的有效性。
这是一项在肺保护性机械通气方案背景下进行的前瞻性队列研究。AVDSF通过以下公式计算：AVDSF = [动脉血二氧化碳分压（PCO）-呼气末二氧化碳分压（etCO）]/PCO。采用受试者工作特征曲线和尤登指数来确定与死亡率相关的AVDSF临界值，据此将患者分为“高或低AVDSF”组。确定AVDSF与严重程度的临床指标之间的相关性[包括每日氧合指数（OI）、入院时儿童死亡率指数2（PIM 2）和儿童逻辑器官功能障碍（PELOD）评分]。主要结局是PARDS患者的死亡率，在高AVDSF组和低AVDSF组之间进行比较，并在多变量逻辑回归分析中进行调整，以校正血管活性药物的使用和PIM 2评分。次要结局包括28天无呼吸机天数（VFD）和无重症监护病房天数（IFD）。
本分析纳入了69例PARDS患者，中位（四分位间距）年龄为4.5（0.8，10.6）岁。每日AVDSF与每日OI相关（ = 0.10； < 0.001）。PARDS前7天的平均AVDSF与PIM 2（ = 0.10； = 0.010）和PELOD（ = 0.12； = 0.004）评分相关。曲线下面积最大时确定的AVDSF临界值为0.22，接近先前建议的0.25。高AVDSF组的死亡率更高[7/19（36.8%）对5/50（10.0%）； = 0.009]，VFD更低[2（0，18）对21（15，24）； = 0.007]，IFD更低[0（0，16）对1（5，21）； = 0.013]。在多变量模型中，处于高AVDSF组[调整后的优势比为4.67（95%置信区间：1.12，19.39）]与死亡率显著相关。
高AVDSF与死亡率增加、VFD和IFD降低独立相关。AVDSF在PARDS风险分层中可能是氧合指数的补充，值得进一步研究。
