Olegård Cecilia, Söndergaard Sören, Houltz Erik, Lundin Stefan, Stenqvist Ola
Department of Anesthesiology and Intensive Care, Sahlgrenska University Hospital, S-413 45 Gothenburg, Sweden.
Anesth Analg. 2005 Jul;101(1):206-12, table of contents. doi: 10.1213/01.ANE.0000165823.90368.55.
We developed a modified nitrogen washin/washout technique based on standard monitors using inspiratory and end-tidal gas concentration values for functional residual capacity (FRC) measurements in patients with acute respiratory failure (ARF). For validation we used an oxygen-consuming lung model ventilated with an inspiratory oxygen fraction (Fio(2)) between 0.3 and 1.0. The respiratory quotient of the lung model was varied between 0.7 and 1.0. Measurements were performed changing Fio(2) with fractions of 0.1, 0.2, and 0.3. In 28 patients with ARF, duplicate measurements were performed. In the lung model, an Fio(2) change of 0.1 resulted in a value of 103 +/- 5% of the reference FRC value of the lung model, and the precision was equally good up to an Fio(2) of 1.0 with a value of 103 +/- 7%. In the patients, duplicate measurements showed a bias of -5 mL with a 95% confidence interval [-38; 29 mL ]. A comparison of a change in Fio(2) of 0.1 with 0.3 showed a bias of -9 mL and limits of agreement of [-365; 347 mL]. This study shows good precision of FRC measurements with standard monitors using a change in Fio(2) of only 0.1. Measurements can be performed with equal precision up to an Fio(2) of 1.0.
我们基于标准监测仪开发了一种改良的氮冲洗/洗脱技术，利用吸气和呼气末气体浓度值来测量急性呼吸衰竭（ARF）患者的功能残气量（FRC）。为进行验证，我们使用了一个吸氧肺模型，其吸入氧分数（Fio₂）在0.3至1.0之间进行通气。肺模型的呼吸商在0.7至1.0之间变化。测量时，Fio₂以0.1、0.2和0.3的幅度进行改变。对28例ARF患者进行了重复测量。在肺模型中，Fio₂变化0.1时，测量值为肺模型参考FRC值的103±5%，直至Fio₂为1.0时精度同样良好，测量值为103±7%。在患者中，重复测量显示偏差为 -5 mL，95%置信区间为[-38; 29 mL]。Fio₂变化0.1与0.3的比较显示偏差为 -9 mL，一致性界限为[-365; 347 mL]。本研究表明，使用标准监测仪，仅将Fio₂改变0.1即可实现FRC测量的良好精度。直至Fio₂为1.0时均可进行精度相同的测量。
