The Multiple Inert Gas Elimination Technique: Current Methodology at the U.S. Army Institute of Surgical Research
ARMY INST OF SURGICAL RESEARCH FORT SAMHOUSTON TX
Pagination or Media Count:
The intrapulmonary causes of hypoxemia include alveolar hypoventilation, ventilation- perfusion VAQ 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 VAQ inequality VAQ 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 VAQ 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 VAQ 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 instruments 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.
- Medicine and Medical Research