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Biomedical subjects

T Kolobow

Publications and source records attributed to T Kolobow.

At least 19 recordsLinked to original sources
PubMed1992

[Acute respiratory failure--support of gas exchange using extracorporeal or implanted oxygenators--present status and future development].

In acute respiratory failure gas exchange can be supported or even maintained in an "alternative" way to mechanical ventilation using extracorporeal techniques (extracorporeal membrane oxygenation ECMO, extracorporeal CO2-removal ECCO2R), or intravenacaval oxygenators (IVOX). These techniques, which are currently in use in neonatology, pediatrics, and adult intensive care medicine, or techniques at present in clinical evaluation (IVOX), are reviewed with their indications, contraindications, differences, problems, worldwide results, and possible future applications.

Acute Disease↗
PubMed1979

The microscopic characterization of multinucleated giant cells formed on polymeric surfaces perfused with blood.

Multinucleated, foreign body giant cells were formed by the fusion of blood monocytes on polymeric membranes perfused with blood during extended extracorporeal circulation. In the current study, heparinized blood, flowing in an arteriovenous shunt in a sheep, perfused polycarbonate, polypropylene and silicone rubber membranes of a recently developed bioartificial tissue culture system. The multinucleated giant cells were studied by light, scanning electron, and transmission electron microscopy, after membrane perfusion for periods of one to two weeks. The giant cells, which were the predominant cellular components of the blood-polymer interface layer, contained from a few to more that one hundred nuclei and varied in diameter up to 400 microns. The cellular interaction with the three membrane types was similar, although fewer mononuclear cells were observed adhering to the silicone rubber membrane. The presence or absence of micropores in the membranes had no effect on the formation of giant cells, nor did the presence of foreign tissue in culture behind the microporous membranes. High blood flow rates and chronic anticoagulation with heparin permitted observation of this foreign body reaction of blood independent of thrombosis.

Animals↗
PubMed1979

Hemodynamic, mechanical and renal effects during "apneic oxygenation" with extracorporeal carbon dioxide removal, at different levels of intrapulmonary pressure in lambs.

It has been shown that apneic oxygenation can be safely performed for many days when metabolic carbon dioxide is removed by an extracorporeal membrane lung, and 100% oxygen is supplied directly into the trachea to keep the intrapulmonary pressure at 5 cm. H2O. The study was designed to find "best intrapulmonary pressure (IP)", analogous to "best PEEP" during continuous positive pressure ventilation. In the present study we have shown that when IP was progressively raised from 5cm H2O to 20 cm H2O the PaO2 rose significantly due to progressive decrease in QVA/Q. A linear positive correlation was found between CO and QVA/Q. There was a negative correlation between QVA/Q and FRC. Total static lung compliance and FRC increased significantly at 15--20 cm H2O IP. There was no significant change in urinary flow, urea and creatinine clearances. We conclude that in apneic oxygenation a more "optimal IP" is attained at an IP pressure of 20 cm H2O than at 5 cm H2O.

Animals↗
PubMed1978

Control of intermittent positive pressure breathing (IPPB) by extracorporeal removal of carbon dioxide.

Five lambs were anaesthetized, paralysed, mechanically ventilated and connected to a membrane "lung" to permit removal of carbon dioxide. When part of the carbon dioxide was removed in this manner, the tidal volume was decreased to keep PaCO2 constant. For example, when 70% of carbon dioxide was removed by the membrane lung, total ventilation was reduced by 50%, peak inspiratory pressure was decreased by 45%, and PaO2 was kept constant by increasing the inspired oxygen fraction from 0.21 to 0.27%. The removal of carbon dioxide by a membrane during positive pressure breathing could decrease barotrauma, particularly in poorly compliant lungs. Technically, the extracorporeal removal of carbon dioxide is relatively simple procedure.

Animals↗
PubMed1978

An alternative to breathing.

If carbon dioxide is removed by an extracorporeal membrane lung ventilated with room air, the natural lung can be used for oxygen transport alone; we have demonstrated this in lambs by maintaining lungs "inflated" with 100 percent oxygen at constant pressure and removing all carbon dioxide through the membrane lung. This process is a variant of "apneic oxygenation" without its disadvantages, because the arterial pH, PCO2, and PO2 all remain normal. No nitrogen washout is needed. These studies were carried out in five lambs anesthetized and paralyzed for 24 hours. For carbon dioxide removal, blood from the subclavin artery was pumped through an extracorporeal membrane lung and was returned into the external jugular vein. For oxygen delivery, the lungs were inflated through a tracheostomy tube with 100 percent oxygen to a pressure of 5 cm. H2O. There was no significant change in arterial blood PO2 after perfusion had begun or at the end of the perfusion 24 hours later. The arterial PCO2 remained steady, and there was no change in acid-base balance. The functional residual capacity (FRC) and static lung compliance remained unchanged. The total dead space was 10 to 15 ml. All animals recovered and survived in good health. At equilibrium, alveolar nitrogen partial pressure was always equal to the partial pressure of nitrogen in the ventilating gas of the membrane lung and was the sole determining factor in controlling alveolar oxygen concentration. Direct measurement of pulmonary gas showed alveolar gas at the level of the carina.

Animals↗
PubMed1978

The promise of the membrane artificial lung.

Membrane lungs are more physiologic than bubble or disc blood oxygenators. Membrane lungs are indispensable in long term perfusions. Recently, there has been a noticeable trend toward use of the membrane lung in open heart surgery. Improper use of the membrane lung lowers its optimum potential and may lead to disenchantment on the part of the user. It is important to recognize that for optimum performance of the membrane lung it is necessary to learn to correctly use the membrane lung.

Artificial Organs↗
PubMed1978

High density tissue culture on microporous membranes perfused by blood: report of a new bioartificial system.

A new tissue culture system has been developed to support high density cell growth using the sheep as the host. Cellular nutrition is provided by plasma solutes as they diffuse from arterial blood across microporous polycarbonate membranes into a device attached to an arteriovenous shunt. Culture chambers are constructed with transparent polycarbonate to allow photomicroscopy of the tissue in situ. System performance is demonstrated by the high density growth of fetal sheep thymus allografts and rat soft tissue sarcoma xenografts.

Animals↗
PubMed1977

Blood compatibility of methyl, methyl vinyl, methyl phenyl, and trifluoropropylmethylvinyl silicone rubber without silica fillers in the spiral-coiled membrane lung.

Spiral-coiled membrane lungs of 0.6 m2 surface area were fabricated from silicone rubber membranes coated with four types of commercially available pure-gum polysiloxane rubber: 1) polytrifluoropropylmethylvinylsiloxane, 2) polymethylphenylsiloxane, 3) polymethylvinylsiloxane, and 4) polydimethylsiloxane. Membranes lungs were tested in an arteriovenous shunt without added heparin after bypass was begun. All group 4 had major rise in resistance to blood flow or clotting in over 33% of the membrane lungs studied, after 6 hr of bypass. Membrane lungs with polydimethylsiloxane (group 4) had no rise in resistance to blood flow during 24 hr of bypass and had the least amount of changes in blood platelet count.

Animals↗
PubMed1977

Control of breathing using an extracorporeal membrane lung.

Various amounts of carbon dioxide were removed through an extracorporeal membrane lung in spontaneously breathing lambs. The decrease in alveolar ventilation was proportional to the fraction of total carbon dioxide removed by the membrane lung. When extracorporeal CO2 removal approximated CO2 production (VCO2), alveolar ventilation almost ceased. Pulmonary ventilation can be controlled by extracorporeal carbon dioxide removal.

Animals↗