Oxygen and carbon dioxide, transfer

Weissman MH and Mockros LF. Oxygen and carbon dioxide transfer in membrane oxygenators. Med. Biol. Eng. 1969 7(2) 169-184. 

In a heart-lung device generally higher partial oxygen feed pressures are applied, i.e. P02 = 0.9 bar. Silicone membranes with a thickness of 100 pm and a P02 = 600 Barrer and a PC02 = 3200 Barrer are used for the oxygen and carbon dioxide transfer Calculate the oxygen flux... 

Cor pulmonare Heart disease developed as a result of pulmonary insufficiency latter part of the disease sequence of asbestosis reflecting the impaired transfer of oxygen and carbon dioxide through the blood vessels of the lung. 

Resistances to the mass transfer of oxygen and carbon dioxide (and also of substrates and products) at the cell surface can be neglected because of the minute size of the cells, which may be only a few microns. The existence of liquid films or the renewal of a liquid surface around these fine particles is inconceivable. The compositions of the broths in well-mixed fermentors can, in practical terms, be assumed uniform. In other words, mass transfer resistance through the main body ofthe broth maybe considered negligible. 

The use of membrane introduction mass spectrometry (MIMS) was first reported in 1963 by Hoch and Kok for measuring oxygen and carbon dioxide in the kinetic studies of photosynthesis [46], The membrane module used in this work was a flat membrane fitted on the tip of a probe and was operated in the MIS mode. The permeated anaytes were drawn by the vacuum in the MS through a long transfer line. Similar devices were later used for the analysis of organic compounds in blood [47], Memory effects and poor reproducibility plagued these earlier systems. In 1974, the use of hollow-fiber membranes in MIMS was reported, which was also operated in the MIS mode [48], Lower detection limits were achieved thanks to the larger surface area provided by hollow fibers. However, memory effects caused by analyte condensation on the wall of the vacuum transfer line remained a problem. 

The key components for process monitoring were selected according to these data and some additional information. The in situ monitoring of the DO as well as the oxygen and carbon dioxide concentrations in the off gas allowed the evaluation of the oxygen transfer rate (OTR), the C02 production rate (CPR) and the respiratory quotient (RQ). The control of the pH-value and the DO was the prerequisite for the maintenance of the optimal growth and product formation conditions. 

The second generation of nonporous membranes was silicon based which displayed increased CO2 permeabilities. In 1965, Bramson et al. commercialized the first nonporous membrane BO [18]. Since the diffusion coefficient of oxygen and carbon dioxide in air is about four orders of magnitude higher than in blood, the gas side mass-transfer resistance was negligible. The major resistance to respiratory gas transfer was due to the membrane and the liquid side concentration boundary layer [19]. Though nonporous membrane BOs reduced blood damage, up to 5.5 m membrane surface area was often required to ensure adequate gas transfer rates. 

Mass transfer equations for oxygen and carbon dioxide ... 

Liquid membrane of fluorocarbons can be formed encapsulating oxygen bubbles in blood. The transfer of oxygen and carbon dioxide through the liquid membrane to and from the blood, respectively, have been shown. Very similar transfer rates with and without liquid membranes indicate that the resistance of the liquid membranes is small. 

Oxygen Transfer—Ot and C02 Response. During the run, a fetal p02 dropping below 14 mm Hg seemed to indicate an inadequate perfusion. If the oxygen supply is eliminated on the maternal side, then resumed, the fetal oxygen tension was observed to successively decrease, then rise to its previous value. At the end of the run, the response of the fetal vessels to oxygen and carbon dioxide was checked to establish the... 

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