The Multiple Inert Gas Elimination Technique: Current Methodology at the U.S. Army Institute of Surgical Research
Abstract
The intrapulmonary causes of hypoxemia include alveolar hypoventilation, ventilation- perfusion (VA/Q) inequality, shunt, and diffusion limitation to oxygen. In the late 1970s, P.D. Wagner developed the Multiple Inert Gas Elimination Technique (MIGET), a method of assessing VA/Q inequality (VA/Q mismatch) and shunt. It can also be used to measure diffusion limitation. In MIGET, the lung is considered as a set of 50 respiratory units, each with a different VA/Q ratio. Six inert gases of varying solubility are infused, and the arterial, mixed venous, and expired air concentrations of the gases are measured under steady-state conditions. Then, distribution of blood flow and ventilation to each of the 50 compartments is calculated. Although technically challenging, this method can be applied in a wide range of basic and clinical settings, and enables the evaluation Of VA/Q mismatch in a relatively low-risk, non-invasive fashion. This report describes the MIGET methodology from a technical standpoint, as currently performed at this Institute. General set-up; assessment of the gas chromatograph instrument's linearity; preparation and infusion of the 6-gas solution; specimen collection; specimen processing, and data analysis are covered in detail. Creation of a new, complex, multi-ramped GC program is described. Instructional videos form part of the multimedia CD-R0M version of this report.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 15, 2002
- Accession Number
- ADA411556
Entities
People
- Andriy I. Batchinsky
- Leopoldo Cancio
Organizations
- United States Army Institute of Surgical Research