减速流机械通气与小儿急性呼吸窘迫综合征中方形流通气的比较。
Mechanical Power in Decelerating Flow versus Square Flow Ventilation in Pediatric Acute Respiratory Distress Syndrome.
机构信息
Department of Anesthesiology and Critical Care, Hospital of the University of Pennsylvania, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania.
Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania.
出版信息
Anesthesiology. 2024 Dec 1;141(6):1095-1104. doi: 10.1097/ALN.0000000000005209.
BACKGROUND
Mechanical power is a summary variable quantifying the risk of ventilator-induced lung injury. The original mechanical power equation was developed using square flow ventilation. However, most children are ventilated using decelerating flow. It is unclear whether mechanical power differs according to mode of flow delivery. This study compared mechanical power in children with acute respiratory distress syndrome who received both square and decelerating flow ventilation.
METHODS
This was a secondary analysis of a prospectively enrolled cohort of pediatric acute respiratory distress syndrome. Patients were ventilated on decelerating flow and then placed in square flow and allowed to stabilize. Ventilator metrics from both modes were collected within 24 h of acute respiratory distress syndrome onset. Paired t tests were used to compare differences in mechanical power between the modes.
RESULTS
This study enrolled 185 subjects with a median oxygenation index of 9.5 (interquartile range, 7 to 13) and median age of 8.3 yr (interquartile range, 1.8 to 14). Mechanical power was lower in square flow mode (mean, 0.46 J · min-1 · kg-1; SD, 0.25; 95% CI, 0.42 to 0.50) than in decelerating flow mode (mean, 0.49 J · min-1 · kg-1; SD, 0.28; 95% CI, 0.45 to 0.53) with a mean difference of 0.03 J · min-1 · kg-1 (SD, 0.08; 95% CI, 0.014 to 0.038; P < 0.001). This result remained statistically significant when stratified by age of less than 2 yr in square flow compared to decelerating flow and also when stratified by age of 2 yr or greater in square flow compared to decelerating flow. The elastic contribution in square flow was 70%, and the resistive contribution was 30%.
CONCLUSIONS
Mechanical power was marginally lower in square flow than in decelerating flow, although the clinical significance of this is unclear. Upward of 30% of mechanical power may go toward overcoming resistance, regardless of age. This is nearly three-fold greater resistance compared to what has been reported in adults.
背景
机械功率是量化呼吸机所致肺损伤风险的综合变量。原始机械功率方程是使用方波流量开发的。然而，大多数儿童使用减速流通气。目前尚不清楚机械功率是否因流量输送方式而异。本研究比较了急性呼吸窘迫综合征患儿接受方波和减速流通气时的机械功率。
方法
这是一项前瞻性纳入的小儿急性呼吸窘迫综合征队列的二次分析。患者先在减速流模式下通气，然后切换到方波模式并稳定 24 小时。在急性呼吸窘迫综合征发病后 24 小时内收集两种模式的呼吸机参数。采用配对 t 检验比较两种模式的机械功率差异。
结果
本研究纳入了 185 名患儿，其氧合指数中位数为 9.5（四分位距，7 至 13），年龄中位数为 8.3 岁（四分位距，1.8 至 14）。方波模式下的机械功率（均值，0.46 J·min-1·kg-1；标准差，0.25；95%置信区间，0.42 至 0.50）低于减速流模式（均值，0.49 J·min-1·kg-1；标准差，0.28；95%置信区间，0.45 至 0.53），平均差异为 0.03 J·min-1·kg-1（标准差，0.08；95%置信区间，0.014 至 0.038；P < 0.001）。与减速流相比，方波中年龄小于 2 岁的患儿之间以及方波中年龄大于等于 2 岁的患儿之间的差异均具有统计学意义。方波中的弹性贡献为 70%，阻力贡献为 30%。
结论
尽管其临床意义尚不清楚，但方波中的机械功率略低于减速流。超过 30%的机械功率可能用于克服阻力，无论年龄大小。与成人报道的相比，这一阻力几乎高了 3 倍。
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