Proquitté Hans, Krause Susann, Rüdiger Mario, Wauer Roland R, Schmalisch Gerd
Clinic of Neonatology (Charité Campus Mitte), Humboldt-University, Berlin, Germany.
Pediatr Crit Care Med. 2004 Jan;5(1):75-80. doi: 10.1097/01.PCC.0000102384.60676.E5.
To investigate the suitability of volumetric capnography for assessing alveolar gas exchange in very small, surfactant-depleted lungs.
Prospective animal trial.
Animal laboratory in a university setting.
Twenty-one ventilated newborn piglets (age <12 hrs; median weight, 890 g; range, 560-1435 g).
Bronchoalveolar lavage with instillation of 30 mL/kg normal saline. Ventilatory, circulatory, and lung mechanic variables were measured before and 0, 30, and 60 mins after bronchoalveolar lavage.
The alveolar deadspace fraction calculated by the Bohr and the Bohr/Enghoff equations increased three-fold (p<.001) after bronchoalveolar lavage in capnograms with distinct alveolar plateau, whereas in capnograms without alveolar plateau no statistical significant difference was seen. The main problem of capnography in small and especially stiff lungs was the high number of discarded records exclusively caused by a missing alveolar plateau. Rates of discarded records of capnography were 9.5% before lavage and increased (p<.01) to 52.4%, 47.6%,42.8% after bronchoalveolar lavage (0, 30, and 60 mins). With decreasing exhalation time, the number of discarded records increased significantly. No plateau was seen in >75% of recorded files with exhalation times <200 msecs. The effect of bronchoalveolar lavage on all variables measured was quite different, with the highest impact on required ventilatory settings, calculated oxygenation variables, and compliance. The effect of bronchoalveolar lavage on arterio-alveolar CO2 difference, CO2 production, and alveolar deadspace was much lower and statistically significant only in capnograms with alveolar plateau.
Volumetric capnography is a useful tool to detect impaired alveolar gas exchange in surfactant-depleted small lungs. However, the method failed if there was no alveolar plateau in the volumetric capnogram especially in stiff lungs with short exhalation times.
探讨容积式二氧化碳描记法评估极小且缺乏表面活性剂的肺脏中肺泡气体交换的适用性。
前瞻性动物试验。
大学环境中的动物实验室。
21头通气的新生仔猪（年龄<12小时；中位体重890克；范围560 - 1435克）。
支气管肺泡灌洗，注入30毫升/千克生理盐水。在支气管肺泡灌洗前以及灌洗后0、30和60分钟测量通气、循环和肺力学变量。
在具有明显肺泡平台的二氧化碳图中，通过玻尔方程和玻尔/恩霍夫方程计算的肺泡死腔分数在支气管肺泡灌洗后增加了三倍（p<0.001），而在没有肺泡平台的二氧化碳图中未观察到统计学上的显著差异。在小的尤其是僵硬的肺脏中，二氧化碳描记法的主要问题是大量记录被舍弃，这完全是由于缺乏肺泡平台所致。二氧化碳描记法记录被舍弃的比例在灌洗前为9.5%，在支气管肺泡灌洗后（0、30和60分钟）增加（p<0.01）至52.4%、47.6%、42.8%。随着呼气时间的缩短，被舍弃记录的数量显著增加。呼气时间<200毫秒的记录文件中，超过75%没有观察到平台。支气管肺泡灌洗对所有测量变量的影响差异很大，对所需通气设置、计算的氧合变量和顺应性影响最大。支气管肺泡灌洗对动脉 - 肺泡二氧化碳差值、二氧化碳产生和肺泡死腔的影响要小得多，且仅在具有肺泡平台的二氧化碳图中有统计学意义。
容积式二氧化碳描记法是检测缺乏表面活性剂的小肺脏中肺泡气体交换受损的有用工具。然而，如果容积式二氧化碳图中没有肺泡平台，尤其是在呼气时间短的僵硬肺脏中，该方法则无法使用。
