Neumann Roland P, Pillow Jane J, Thamrin Cindy, Larcombe Alexander N, Hall Graham L, Schulzke Sven M
Department of Neonatology, University Children's Hospital Basel (UKBB), Basel, Switzerland.
Neonatology. 2015;107(1):43-9. doi: 10.1159/000366153. Epub 2014 Nov 6.
Ventilated preterm infant lungs are vulnerable to overdistension and underinflation. The optimal ventilator-delivered tidal volume (VT) in these infants is unknown and may depend on the extent of alveolarisation at birth.
We aimed to calculate respiratory dead space (VD) from the molar mass (MM) signal of an ultrasonic flowmeter (VD,MM) in very preterm infants on volume-targeted ventilation (VT target, 4-5 ml/kg) and to study the association between gestational age (GA) and VD,MM-to-VT ratio (VD,MM/VT), alveolar tidal volume (VA) and alveolar minute volume (AMV).
This was a single-centre, prospective, observational, cohort study in a neonatal intensive care unit. Tidal breathing analysis was performed in ventilated very preterm infants (GA range 23-32 weeks) on day 1 of life.
Valid measurements were obtained in 43/51 (87%) infants. Tidal breathing variables were analysed using multivariable linear regression. VD,MM/VT was negatively associated with GA after adjusting for birth weight Z score (p < 0.001, R(2) = 0.26). This association was primarily influenced by the appliance dead space. Despite similar VT/kg and VA/kg across all studied infants, respiratory rate and AMV/kg increased with GA.
VD,app rather than anatomical VD is the major factor influencing increased VD,MM/VT at a younger GA. A volume guarantee setting of 4-5 ml/kg in the Dräger Babylog® 8000 plus ventilator may be inappropriate as a universal target across the GA range of 23-32 weeks. Differences between measured and set VT and the dependence of this difference on GA require further investigation.
机械通气的早产婴儿肺部易出现过度扩张和通气不足。这些婴儿最佳的呼吸机输送潮气量（VT）尚不清楚，可能取决于出生时肺泡化程度。
我们旨在根据超声流量计的摩尔质量（MM）信号计算极早产儿在容量靶向通气（VT目标值为4 - 5 ml/kg）时的呼吸死腔（VD），并研究胎龄（GA）与VD、MM与VT的比值（VD,MM/VT）、肺泡潮气量（VA）和肺泡分钟通气量（AMV）之间的关系。
这是一项在新生儿重症监护病房进行的单中心、前瞻性、观察性队列研究。在出生第1天对机械通气的极早产儿（GA范围为23 - 32周）进行潮气呼吸分析。
在51名婴儿中的43名（87%）获得了有效测量结果。使用多变量线性回归分析潮气呼吸变量。在校正出生体重Z评分后，VD,MM/VT与GA呈负相关（p < 0.001，R(2) = 0.26）。这种关联主要受设备死腔影响。尽管所有研究婴儿的VT/kg和VA/kg相似，但呼吸频率和AMV/kg随GA增加。
设备死腔（VD,app）而非解剖学死腔是影响极早产儿胎龄较小时VD,MM/VT增加的主要因素。在德尔格Babylog® 8000 plus呼吸机中设置4 - 5 ml/kg的容量保证作为23 - 32周GA范围内的通用目标可能不合适。测量的VT与设定的VT之间的差异以及这种差异对GA的依赖性需要进一步研究。
