W. Isselhard

Miniature equipment for the perfusion of rat limbs

SummaryA simple, reliable and efficient miniaturized extracorporeal circulation system for the use in small animals, especially for the perfusion of rat hind limbs, has been described. The system consists of a newly devised bubble oxygenator and heat exchanger and of commercially available roller pumps, polyethylene cannulas and silicone tubes. The minimal and maximal priming volume of the entire system is 4.7 and 16.7 ml, respectively. The efficiency of the system is reflected in a high value of oxygen uptake in the range of 0.061 ml O2·min−1·ml−1 blood, a heat transfer coefficient ranging from 0.96 to 0.31 at flow rates between 1 and 20 ml·min−1, a low pulsation amplitude of the roller pump, a constant flow resistance at the arterial cannula, which implies optimal flow conditions, and in a low blood trauma with plasma hemoglobin concentrations of 47.5 ± 5mg dl−1 after 60min of in vitro perfusion.

Eine modifizierte Farbstoffverdünnungsmethode zur Überprüfung der Kreislaufisolierung der Extremität während regionaler Perfusion

SummaryIn experiments on dogs (n = 13) we tested a procedure for estimating leakage during regional perfusion of the extremity by means of a dye dilution method. After systematic application of 0.5% Evans blue solution (0.1 ml/kg b.w.) we measured the dye concentration in plasma by means of a spectral photometer. The plasma volume (5.5 ml/100 g b.w.) and the disappearance rate of the dye (10%/h) were calculated. In a second procedure the supplying artery and vein of the extremity were proximally clamped and distally connected to an extracorporeal circulation unit consisting of oxygenator, pump, and heat exchanger, and the isolation of the extremity was tested. By simulation of leakage it was possible to detect a little amount of shunt of about 1% escaping from isolated region into the systemic circulation. There were no hints to toxicity when the same dye concentration was applied.The standardized method was used during 132 cytostatic hyperthermic perfusions in man. In 20 patients we determined shunts of less than 5%, in 104 patients shunts between 5 and 10%, and in eight patients shunts of 10–20% of the extracorporeal circulation.The benefits of the described method are simplicity to carry out and missing of toxicity or radiation.ZusammenfassungIm Tierexperiment am Hund (n = 13) prüften wir die Anwendung des Farbstoffes Evans blau als Indikator zur Kontrolle der Kreislaufisolierung einer Extremität während regionaler Perfusion. Nach i.v. Gabe von 0,1 ml/kg Körpergewicht einer 0,5%igen Evans-Blau-Lösung in den Körperkreislauf bestimmten wir die Plasmakonzentration des Farbstoffes mittels eines Spektralsphotometers. Wir ermittelten das Plasmavolumen (5,5 ml/100 g Körpergewicht) und die Eliminationsgeschwindigkeit des Farbstoffes (10%/h). Im zweiten Arbeitsansatz wurde nach Anschluß der versorgenden Gefäße der Extremität an eine extracorporale Kreislaufeinheit, bestehend aus Rollerpumpe, Oxygenator und Wärmeaustauscher, die Kreislaufisolierung der Extremität geprüft und die Situation eines Lecks nachgeahmt. Mit dieser modifizierten Farbstoffverdünnungsmethode war es uns möglich, „Shunt-Mengen“ von 1% des extracorporalen Kreislaufvolumens nachzuweisen. Bei der verwendeten Farbstoffkonzentration ergaben sich keine Hinweise für Toxizität.Das im Tierexperiment standardisierte Verfahren verwendeten wir bei 132 Patienten während regionaler hyperthermer Perfusion der Extremitäten. Bei 20 Patienten bestimmten wir ein Leck von weniger als 5%, bei 104 Patienten 5–10%, bei acht Patienten ein Leck von 10–20% des extracorporalen Kreislaufvolumens.Die Vorteile dieser Methode sind die einfache Handhabung, die fehlende Toxizität und Strahlenbelastung und der geringe finanzielle Aufwand.

Involvement of oxygen in harvesting injury of the liver: An experimental study including substrate free organ persufflation to evaluate a specific therapeutic approach

SummaryThe present study was undertaken to assess the role of oxygen free radicals relating to cell damage upon reoxygenation of the ischemically altered isolated rat liver. Livers were excised and flushed via the portal vein with Ringers solution and Euro-Collins solution, to which superoxide dismutase (SOD) was added in the experimental group. After warm ischemia at 37°C and cold storage at 4°C, the livers were reperfused via the portal vein with carbogensaturated Krebs-Henseleit solution. Other livers were subjected to a retrograde persufflation via the infrahepatic caval vein with either oxygen or nitrogen and then rinsed with Ringers solution. During reperfusion, SOD-treated livers showed markedly reduced vascular resistance, lower enzyme release and enhanced VO2 accordingly, energy charge at the end of reperfusion was significantly higher in the treated group. With reference to the tissue content of malondialdehyde, SOD-treated livers showed significantly less damage than the controls. Our experiments with substrate-free persufflation provided sound corroboration for these data. Enzyme activities in the eluate were significantly reduced under anoxic conditions as well as in the presence of SOD. We conclude from these data that oxygen free radicals do exert a detrimental impact on the reoxygenated liver, which could be specifically suppressed by application of exogenous SOD.

Absence of mitochondrial enhancement in the remnant liver after partial hepatectomy in cirrhotic rats

SummaryChanges in energy metabolism after 70% partial hepatectomy were investigated in normal and carbon-tetrachloride-(CCl4)-induced-cirrhotic rats by evaluating hepatic mitochondrial ATP synthesizing activity as well as liver tissue levels of adenine nucleotides and lipid peroxide. Preoperative concentrations of ATP and total adenine nucleotides (TAN: ATP+ADP+AMP) in μmol/g dry weight (dw) and the energy charge potential (ECP) in the cirrhotic livers were 8.53 SEM 0.25, 14.73 SEM 0.54, and 0.74 SEM 0.01, respectively, and were significantly lower than those of normal livers (12.04 SEM 0.34, 15.75 SEM 0.12, and 0.86 SEM 0.01,P<0.01 in TAN). There was no difference in the preoperative mitochondrial phosphorylation rate (PR=×10−10 mol ATP/sec per mg mitochondrial protein) between normal and cirrhotic livers (21.01 SEM 0.95 and 21.55 SEM 1.03, respectively). After hepatectomy, in the normal livers these values decreased slightly after 12 h, remained low until 48 h, and returned to the preoperative value at 72 h. PR was remarkably enhanced and reached the maximum level of 32.54 SEM 2.07 at 24 h (P<0.001, compared to the sham-operated rats) adn gradually returned to the preoperative value at 72 h. In the cirrhotic livers, ATP and ECP levels were drastically decreased at 12 h and recovered to the preoperative levels within 24 h, while TAN level remained unchanged. Enhancement of PR was not observed in any of the cirrhotic livers during the experiment. Lipid peroxidation was transiently increased postoperatively with no difference between normal and cirrhotic livers both in the sham-operated and the hepatectomized rats. These findings suggest that the energy status was more depressed in the cirrhotic livers than in normal livers both before and after hepatectomy. This depressed energy status might be attributed to the low preoperative tissue levels of adenine nucleotides and ECP level in the cirrhotic livers as well as to the absence of the enhancement of PR in the remnant livers.

355. Reduktion der Tierversuche in der Chirurgie. Entwicklung und Erprobung einer neuen chirurgischen Methode am Modell

SummaryFor the development, testing and further modification of surgical techniques, experiments with animals are not always vitally necessary. The example of the new method for the “transanal endoscopic operation” will demonstrate how phantom models can replace the tests formerly required. Since 1983, successful rectal operations have been performed by this new surgical method, which was developed using the phantom model technique.ZusammenfassungFür die Entwicklung, Erprobung und Weiterbildung in der Chirurgie sind Tierversuche nicht immer zwingend erforderlich. Am Beispiel der neuen Methode zur „Transanalen Endoskopischen Operation” wird gezeigt, wie Phantommodelle sinnvoll die oben aufgeführte Aufgabenstellung übernehmen können. Mit der so entwickelten Technik sind seit 1983 85 Rectumeingriffe am Menschen mit Erfolg durchgeführt worden.

Blut, Plasma, synthetische Lösungen als Vehikel zur Kardioplegie — Ein Vergleich an stillgestellten, ischämischen Herzen

Kardioplegie ist heute in der Klinik ein allgemein akzeptiertes Prinzip zur herzchirurgischen Myokardprotektion. Die Anwendung von mit Kalium angereichertem Blut in Kombination mit Hypothermie zur Kardioplegie wurde 1978 von FOLLETTE et al. (1) empfohlen und wird seitdem von zahlreichen Autoren als vorteilhaft angesehen (2). Die Beurteilung der Blutkardioplegie ist jedoch kontrovers (3), da der Blutkardioplegie auch nachteilige Auswirkungen zugeschrieben werden (z.B. Mikrozirkulationsstorungen).

372. Die endoskopische Operation in der Rectumhöhle

SummaryThe use of newly designed instruments allows surgical operations in the rectum up to 20 cm from the dentate line under endoscopic control. The rectum has to be widened by a combination of mechanical and pneumatic dilatation. The stereoscopic oblique-angle instrument is adjusted to the operation-area. We can use up to four instruments simultaneously. After injection of POR (ornipressin) into the mucosa we have excised areas 3 cm in diameter. The defect is closed by continuous suture.ZusammenfassungWir können mit einem neu entwickelten Instrumentarium unter endoskopischer Kontrolle in der Rectumhöhle differenzierte, chirurgische Eingriffe bis in 20 cm Höhe durchführen. Dazu wird die Rectumhöhle unter kombinierter mechanischer und pneumatischer Dehnung entfaltet und der zu operierende Prozeß mit einer stereoskopischen Winkeloptik eingestellt. Für die Operation können bis zu 4 Instrumente gleichzeitig eingesetzt werden. Wir haben Schleimhautexcisionen von 3 cm Durchmesser nach POR (Ornipressin)-Unterspritzung vorgenommen und den entstandenen Defekt mit einer fortlaufenden Naht verschlossen.

[A new method for isolated regional perfusion of the liver in vivo. Experimental studies (author's transl)].

SummaryThe canine liver was isolated from its blood supply and perfused for one hour normothermically by means of a new catheter and a perfusion system consisting of oxygenator, pump and heat-exchanger. Hemodynamic parameters, blood gas analyses, and tissue metabolites were evaluated during the experiments. The venous return from the lower body and portal vein (1.113 1/min) could be maintained with the catheter system so that the mean systemic arterial pressure was within normal limits. With a perfusion rate through the liver of 0,55 ml/min/g and perfusion pressure of 10 cm H2O there was an adequate tissue perfusion; this was also shown by blood gas analyses and tissue metabolite concentrations. Using dye dilution methods the isolation of the liver was tested. This showed a leakage of 6–7% of the total perfusion volume. This new method makes it possible to carry out an isolated, normothermic, liver perfusion for one hour without irreversible tissue damage.ZusammenfassungDie Leber des Hundes wurde von der Gefäßversorgung abgeriegelt, mit Hilfe eines neu entwickelten Kathetersystems und eines Perfusionsaggregates 1 h normotherm und in Rezirkulation perfundiert. Kreislaufparameter, Blutgasanalysen und Gewebsgehalte der Stoffwechselmetabolite wurden zur Beurteilung der Methode herangezogen. Das venöse Blut aus der unteren Körperhälfte und dem portalen Stromgebiet (1,113 l/min) konnten über das Kathetersystem zum Herzen zurückgeführt werden, so daß der mittlere arterielle Systemdruck im Normbereich blieb. Bei einem Perfusionsfluß durch die Leber von 0,55 ml/min/g und einem Perfusionsdruck von 10 cm H2O war eine ausreichende Sauerstoffzufuhr gewährleistet, welcher auch in den Blutgasanalysen und in den Stoffwechseluntersuchungen zum Ausdruck kam. Mit der Anwendung einer Farbstoffverdünnungsmethode wurde die Kreislaufisolierung der Leber geprüft; dabei waren lediglich Leckmengen von 6–7% des gesamten Perfusionskreislaufvolumens festzustellen. Das neue Verfahren ermöglicht eine einstündige, normotherme, isolierte Leberperfusion ohne das gesunde Gewebe irreversibel zu schädigen.