Rees Stephen Edward, Kjaergaard Søren, Perthorgaard Per, Malczynski Jerzy, Toft Egon, Andreassen Steen
Center for Model Based Medical Decision Support, Aalborg University, Denmark.
J Clin Monit Comput. 2002 Jan;17(1):43-52. doi: 10.1023/a:1015456818195.
Clinical measurements of pulmonary gas exchange abnormalities might help prevent hypoxaemia and be useful in monitoring the effects of therapy. In clinical practice single parameters are often used to describe the abnormality e.g., the "effective shunt." A single parameter description is often insufficient, lumping the effects of several abnormalities. A more detailed picture can be obtained from experiments where FiO2 is varied and two parameters estimated. These experiments have previously taken 30-40 minutes to complete, making them inappropriate for routine clinical use. However with automation of data collection and parameter estimation, the experimental time can be reduced to 10-15 minutes.
A system has been built for non-invasive, Automatic, Lung Parameter Estimation (ALPE). This system consists of a ventilator, a gas analyser with pulse oximeter, and a computer. Computer programs control the experimental procedure, collect data from the ventilator and gas analyser, and estimate pulmonary gas exchange parameters. Use of the ALPE system, i.e. in estimating gas exchange parameters and reducing experimental time, has been tested on five normal subjects, two patients before and during diuretic therapy, and on 50 occasions in patients before and after surgical intervention.
The ALPE system provides estimation of pulmonary gas exchange parameters from a simple, clinical, non-invasive procedure, automatically and quickly. For normal subjects and in patients receiving diuretic therapy, data collection by clinicians familiar with ALPE took (mean +/- SD) 13 min 40 sec +/- 1 min 23 sec. For studies on patients before and after surgery, data collection by an intensive care nurse took (mean +/- SD) 10 min 47 sec +/- 2 min 14 sec. Parameter estimates were: for normal subjects, shunt = 4.95% +/- 2.64% and fA2 = 0.89 +/- 0.01; for patients with heart failure prior to diuretic therapy, patient 1, shunt = 11.50% fA2 = 0.41, patient 2 shunt = 11.61% fA2 = 0.55; and during therapy: patient 1, shunt = 11.51% fA2 = 0.71, patient 2, shunt = 11.22% fA2 = 0.49.
The ALPE system provides quick, non-invasive estimation of pulmonary gas exchange parameters and may have several clinical applications. These include, monitoring pulmonary gas exchange abnormalities in the ICU, assessing post-operative gas exchange abnormalities, and titrating diuretic therapy in patients with heart failure.
对肺气体交换异常进行临床测量可能有助于预防低氧血症，并有助于监测治疗效果。在临床实践中，常使用单一参数来描述异常情况，例如“有效分流”。单一参数描述往往不够充分，它将多种异常情况的影响混为一谈。通过改变吸入氧分数（FiO₂）并估算两个参数的实验，可以获得更详细的情况。此前，这些实验需要30 - 40分钟才能完成，因此不适合常规临床使用。然而，随着数据收集和参数估算的自动化，实验时间可缩短至10 - 15分钟。
构建了一个用于无创自动肺参数估算（ALPE）的系统。该系统由一台呼吸机、一台带有脉搏血氧仪的气体分析仪和一台计算机组成。计算机程序控制实验过程，从呼吸机和气体分析仪收集数据，并估算肺气体交换参数。已在5名正常受试者、2名接受利尿剂治疗前后的患者以及50例手术干预前后的患者身上测试了ALPE系统在估算气体交换参数和缩短实验时间方面的应用。
ALPE系统能通过简单、临床、无创的程序自动且快速地估算肺气体交换参数。对于正常受试者和接受利尿剂治疗的患者，熟悉ALPE的临床医生收集数据的时间为（均值±标准差）13分40秒±1分23秒。对于手术前后患者的研究，重症监护护士收集数据的时间为（均值±标准差）10分47秒±2分14秒。参数估算结果为：正常受试者，分流率 = 4.95%±2.64%，fA₂ = 0.89±0.01；利尿剂治疗前的心力衰竭患者，患者1，分流率 = 11.50%，fA₂ = 0.41，患者2，分流率 = 11.61%，fA₂ = 0.55；治疗期间：患者1，分流率 = 11.51%，fA₂ = 0.71，患者2，分流率 = 11.22%，fA₂ = 0.49。
ALPE系统能快速、无创地估算肺气体交换参数，可能有多种临床应用。这些应用包括，在重症监护病房监测肺气体交换异常、评估术后气体交换异常以及调整心力衰竭患者的利尿剂治疗。
