title: Multiple inert gas elimination technique by micropore membrane inlet mass spectrometry--a comparison with reference gas chromatography.
abstract: The mismatching of alveolar ventilation and perfusion (VA/Q) is the major determinant of impaired gas exchange. The gold standard for measuring VA/Q distributions is based on measurements of the elimination and retention of infused inert gases. Conventional multiple inert gas elimination technique (MIGET) uses gas chromatography (GC) to measure the inert gas partial pressures, which requires tonometry of blood samples with a gas that can then be injected into the chromatograph. The method is laborious and requires meticulous care. A new technique based on micropore membrane inlet mass spectrometry (MMIMS) facilitates the handling of blood and gas samples and provides nearly real-time analysis. In this study we compared MIGET by GC and MMIMS in 10 piglets: 1) 3 with healthy lungs; 2) 4 with oleic acid injury; and 3) 3 with isolated left lower lobe ventilation. The different protocols ensured a large range of normal and abnormal VA/Q distributions. Eight inert gases (SF6, krypton, ethane, cyclopropane, desflurane, enflurane, diethyl ether, and acetone) were infused; six of these gases were measured with MMIMS, and six were measured with GC. We found close agreement of retention and excretion of the gases and the constructed VA/Q distributions between GC and MMIMS, and predicted PaO2 from both methods compared well with measured PaO2. VA/Q by GC produced more widely dispersed modes than MMIMS, explained in part by differences in the algorithms used to calculate VA/Q distributions. In conclusion, MMIMS enables faster measurement of VA/Q, is less demanding than GC, and produces comparable results.
authors.affiliation: Department of Surgical Sciences, Anesthesia and Intensive Care, Uppsala University, Uppsala, Sweden;
authors.forename: Moritz
authors.initials: M
authors.lastname: Kretzschmar
authors.forename: Thomas
authors.initials: T
authors.lastname: Schilling
authors.forename: Andreas
authors.initials: A
authors.lastname: Vogt
authors.forename: Hans Ulrich
authors.initials: HU
authors.lastname: Rothen
authors.forename: João Batista
authors.initials: JB
authors.lastname: Borges
authors.forename: Thomas
authors.initials: T
authors.lastname: Hachenberg
authors.forename: Anders
authors.initials: A
authors.lastname: Larsson
authors.forename: James E
authors.initials: JE
authors.lastname: Baumgardner
authors.forename: Göran
authors.initials: G
authors.lastname: Hedenstierna
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002138:Calibration; D002849:Chromatography, Gas / Q000592:standards; D004195:Disease Models, Animal; D004867:Equipment Design; D008401:Gas Chromatography-Mass Spectrometry / Q000295:instrumentation / Q000379:methods / Q000592:standards; D006985:Hyperventilation / Q000097:blood / Q000209:etiology / Q000503:physiopathology; D055370:Lung Injury / Q000097:blood / Q000139:chemically induced / Q000503:physiopathology; D008365:Manometry; D008567:Membranes, Artificial; D008851:Micropore Filters; D005741:Noble Gases / Q000097:blood*; D019301:Oleic Acid; D010313:Partial Pressure; D016062:Porosity; D011652:Pulmonary Circulation; D011659:Pulmonary Gas Exchange; D012123:Pulmonary Ventilation; D012015:Reference Standards; D012121:Respiration, Artificial; D013552:Swine; D013997:Time Factors; D014692:Ventilation-Perfusion Ratio
chemical_list: D008567:Membranes, Artificial; D005741:Noble Gases; D019301:Oleic Acid
keywords: MIGET; gas chromatography; inert gases; mass spectrometry; membrane inlet; ventilation/perfusion distributions