Noninvasive Multiple Inert Gas Elimination Technique

描述（由申请人提供）：血液氧合不足（低氧血症）是ICU患者的常见症状，可能由四种不同病理的组合引起：1）肺泡通气减少（通气不足），2）氧气扩散受限，3）通气/灌注不均衡，4）分流。低氧血症可以通过以下任何生理参数进行评估：1）动脉PO 2和PCO 2，2）肺泡和动脉PO 2的差异，3）静脉混合（称为生理分流），以及4）生理死腔。然而，虽然这些参数在临床上是有用的，但它们提供的信息非常有限，并且在不满足基本假设时容易被误解。在大多数情况下，低氧血症的确切原因是难以区分在任何给定的患者使用目前可用的工具。20世纪70年代初引入了多重惰性气体消除技术（MIGET），作为克服上述经典方法所施加的许多限制的一种方式。MIGET的独特之处在于它使用惰性气体数据来量化急性疾病中O2和CO2气体交换的许多病理特征。利用应用于惰性气体（与O2和CO2相比）的更简单的气体交换模型，MIGET提供了通气和血流相对于V& / Q&比的定量分布。正是这些分布的获取形成了MIGET提供的O2和CO2气体交换参数的许多计算的基础。重要的是，MIGET的一个特殊优势是它将低V& A / Q&比的区域与不通气区域（分流）区分开，并且还将高V& A / Q&比的区域与未灌注的肺区分开。MIGET还允许对气体交换的额外见解，包括1）识别O2扩散限制的存在，以及2）定量肺外因素对动脉PO 2和PCO 2气体交换限制的作用。 然而，由于以下原因，MIGET从未从研究工具发展为临床管理工具：1）测量时间延迟; 2）操作复杂性;以及3）实质性侵入性。这项拟议工作的目标是开发和验证仪器和方法，提供复杂的V& / Q&分布和分析的MIGET -但没有提到的缺点。 公共卫生相关性：30多年来，MIGET（多种惰性气体消除技术）一直是用于了解和表征肺部异常的有价值的研究工具。来自该技术的生理信息可以大大改善重症监护室（ICU）的治疗，但高度侵入性的方法使其在任何临床环境中都不切实际。该建议的无创MIGET系统（NIMS）有可能提供MIGET信息，以改善ICU内外的患者管理。

DESCRIPTION (provided by applicant): Insufficient oxygenation of the blood (hypoxemia) is a common symptom in ICU patients, and may be caused by a combination of four different pathologies: 1) decreased alveolar ventilation (hypoventilation), 2) oxygen diffusion limitation, 3) inequality in ventilation/perfusion, and 4) shunts. Hypoxemia can be assessed by any of the following physiological parameters: 1) arterial PO2 and PCO2, 2) difference in alveolar and arterial PO2, 3) venous admixture (known as a physiological shunt), and 4) physiological dead space. However, while these parameters are clinically useful, they offer quite limited information and are subject to misinterpretation when the underlying assumptions are not met. For the most part, the exact causes of hypoxemia are difficult to distinguish in any given patient using presently available tools. A multiple inert gas elimination technique (MIGET) was introduced in the early 1970s as a way to overcome many of the limitations imposed by the classical methods mentioned above. The uniqueness of MIGET is its use of inert gas data to quantitate the many pathological features of O2 and CO2 gas exchange in the acutely ill. Taking advantage of simpler gas exchange models applied to inert gases (compared to O2 and CO2), MIGET provides quantitative distributions of ventilation and blood flow with respect to V& / Q& ratio. It is the acquisition of these distributions that form the basis for the many calculations of O2 and CO2 gas exchange parameters that MIGET provides. Importantly, a special strength of MIGET is that it distinguishes regions of low V& A / Q& ratio from unventilated regions (shunt), and also regions of high V& A / Q& ratio from unperfused lung. MIGET also allows additional insights into gas exchange, which include 1) identification of the presence of diffusion limitation for O2, and 2) quantification of the role of extrapulmonary factors on arterial PO2 and PCO2 gas exchange limitation. However, MIGET has never evolved from a research tool to a clinical management tool due to: 1) measurement time delays; 2) operational complexity; and 3) substantial invasiveness. The goal of this proposed work is to develop and validate the instrumentation and methodology that provides the complex V& / Q& distribution and analysis of MIGET - but without the cited disadvantages. PUBLIC HEALTH RELEVANCE: For over 30 years, MIGET (Multiple Inert Gas Elimination Technique) has been a valuable research tool used to understand and characterize lung abnormalities. Physiological information from this technique could greatly improve therapy in the Intensive Care Unit (ICU), but the highly invasive methods make it impractical in any clinical setting. This proposed Non-Invasive MIGET System (NIMS) has the potential to provide MIGET information to improve patient management both in and outside of the ICU.