Bourgoin Pierre, Baudin Florent, Brossier David, Emeriaud Guillaume, Wysocki Marc, Jouvet Philippe
Pediatric Intensive Care Unit, Hopital Femme-Enfant-Adolescent, Centre Hospitalier Universitaire de Nantes, Nantes, France.
Centre Hospitalier Universitaire de Lyon, Lyon, France.
Respir Care. 2017 Apr;62(4):468-474. doi: 10.4187/respcare.05108. Epub 2017 Feb 21.
Recent findings suggest that using alveolar P (P ) estimated by volumetric capnography in the Bohr equation instead of P (Enghoff modification) could be appropriate for the calculation of physiological dead space to tidal volume ratio (V/V and V/V, respectively). We aimed to describe the relationship between these 2 measurements in mechanically ventilated children and their significance in cases of ARDS.
From June 2013 to December 2013, mechanically ventilated children with various respiratory conditions were included in this study. Demographic data, medical history, and ventilatory parameters were recorded. Volumetric capnography indices (NM3 monitor) were obtained over a period of 5 min preceding a blood sample. Bohr's and Enghoff's dead space, S2 and S3 slopes, and the S2/S3 ratio were calculated breath-by-breath using dedicated software (FlowTool). This study was approved by Ste-Justine research ethics review board.
Thirty-four subjects were analyzed. Mean V/V was 0.39 ± 0.12, and V/V was 0.47 ± 0.13 ( = .02). The difference between V/V and V/V was correlated with P /F and with S2/S3. In subjects without lung disease (P /F ≥ 300), mean V/V was 0.36 ± 0.11, and V/V was 0.39 ± 0.11 ( = .056). Two children with status asthmaticus had a major difference between V/V and V/V in the absence of a low P /F .
This study suggests that V/V and V/V are not different when there is no hypoxemia (P /F > 300) except in the case of status asthmaticus. In subjects with a low P /F , the method to measure V/V must be reported, and results cannot be easily compared if the measurement methods are not the same.
最近的研究结果表明，在玻尔方程中使用通过容积式二氧化碳描记法估算的肺泡P（P）而非P（恩霍夫修正法），可能适用于计算生理死腔与潮气量之比（分别为V/V和V/V）。我们旨在描述机械通气儿童中这两种测量方法之间的关系及其在急性呼吸窘迫综合征（ARDS）病例中的意义。
2013年6月至2013年12月，本研究纳入了患有各种呼吸疾病的机械通气儿童。记录人口统计学数据、病史和通气参数。在采集血样前5分钟内获取容积式二氧化碳描记法指标（NM3监测仪）。使用专用软件（FlowTool）逐次呼吸计算玻尔和恩霍夫死腔、S2和S3斜率以及S2/S3比值。本研究经圣贾斯汀研究伦理审查委员会批准。
对34名受试者进行了分析。平均V/V为0.39±0.12，V/V为0.47±0.13（P = 0.02）。V/V和V/V之间的差异与P/F以及S2/S3相关。在无肺部疾病（P/F≥300）的受试者中，平均V/V为0.36±0.11，V/V为0.39±0.11（P = 0.056）。两名哮喘持续状态患儿在P/F不低的情况下，V/V和V/V之间存在显著差异。
本研究表明，除哮喘持续状态外，在无低氧血症（P/F>300）时，V/V和V/V没有差异。在P/F较低的受试者中，必须报告测量V/V的方法，如果测量方法不同，则结果不易比较。
