Improved adhesion and proliferation of human endothelial cells on polyethylene precoated with monoclonal antibodies directed against cell membrane antigens and extracellular matrix proteins.

Endothelial cell seeding may improve the patency of synthetic vascular grafts provided that platelet reactivity of nonendothelialized sites is not increased. We have investigated if surface-adsorbed monoclonal antibodies directed against endothelial cell membrane proteins and against extracellular matrix proteins promote the adhesion and proliferation of cultured human endothelial cells, without causing platelet deposition at non-endothelialized sites. Adhesion of endothelial cells onto polyethylene coated with monoclonal antibodies directed against endothelial cell-specific membrane antigens, integrin receptors and glycoprotein CD31 was equal to or higher than adhesion onto fibronectin-coated polyethylene. Endothelial cells did not proliferate on these surface-adsorbed antibodies. However, pre-coating of polyethylene with mixtures of endothelial cell-specific monoclonal antibodies and monoclonal antibodies directed against fibronectin or von Willebrand factor, resulted in relatively high adhesion and optimal proliferation. Platelet reactivity of the polyethylene surface was found to significantly increase after adsorption of fibronectin, endothelial cell-specific monoclonal antibody or its Fc fragments. In contrast, adsorption of F(ab')2 fragments of endothelial cell-specific monoclonal antibody did not promote platelet deposition. Therefore, it is concluded that coating of vascular graft materials with mixtures of F(ab')2 fragments of monoclonal antibodies specifically directed against endothelial cells and against extracellular matrix proteins may be an effective way to both promote the growth of seeded endothelial cells and limit platelet-graft interaction.     

Multicenter Randomized Comparison of Xenon and Isoflurane on Left Ventricular Function in Patients Undergoing Elective Surgery

Background: Volatile anesthetics are commonly used for general anesthesia. However, these can induce profound cardiovascular alterations. Xenon is a noble gas with potent anesthetic and analgesic properties. However, it is uncertain whether xenon alters myocardial function. The aim of this study was therefore to investigate left ventricular function during anesthesia with xenon compared with isoflurane.

Methods: The authors performed a randomized multicenter trial to compare xenon with isoflurane with respect to cardiovascular stability and adverse effects in patients without cardiac diseases scheduled for elective surgery. Two hundred fifty-nine patients were enrolled in this trial, of which 252 completed the study according to the protocol. Patients were anesthetized with xenon or isoflurane, respectively. Before administration of the study drugs and at four time points, the effects of both anesthetics on left ventricular function were investigated using transesophageal echocardiography.

Results: Global hemodynamic parameters were significantly altered using isoflurane (P < 0.05 vs. baseline), whereas xenon only decreased heart rate (P < 0.05 vs. baseline). In contrast to xenon, left ventricular end-systolic wall stress decreased significantly in the isoflurane group (P < 0.05 vs. baseline). Velocity of circumferential fiber shortening was decreased significantly in the xenon group but showed a more pronounced reduction during isoflurane administration (P < 0.05 vs. baseline). The contractile index (difference between expected and actually measured velocity of circumferential fiber shortening) as an independent parameter for left ventricular function was significantly decreased after isoflurane (P < 0.0001) but unchanged using xenon.     

The use of antithrombotic drugs during various surgical procedures]

Neuraxial blockade has been shown to provide essential benefits in terms of reduced perioperative morbidity and mortality. Case series from recent years indicate that spinal epidural hematoma is more common than previously estimated, with incidences of 1:200,000 in obstetric patients and as high as 1:3,600 in female orthopedic patients. To lower this risk, societies worldwide have issued guidelines establishing recommended time intervals between administration of antithrombotic drugs and performance of neuraxial blockade. If adherence to these intervals imposes a high risk of theomboembolic complications, neuraxial blockade should be withheld in favor of continued antithrombotic therapy. In such patients an alternative plan for postoperative pain management such as patient-controlled intravenous analgesia or peripheral nerve blocks should be established. In patients on continued acetylsalicylic acid therapy, neuraxial blockade may be performed if thromboembolism prophylaxis is not administered concurrently.     

Monitoring patients in the anesthesia recovery room. Continuous transcutaneous O2 and CO2 measurements]

To establish whether continuous transcutaneous O2 and CO2 measurement in the recovery room is suitable for non-invasive monitoring of spontaneous respiration in patients newly operated upon, comparative transcutaneous and arterial pO2 and pCO2 investigations were carried out on 35 adults. There was a correlation coefficient of 0.66 between paO2 and tcpO2. The transcutaneous pO2 values measured were 45.3 mm Hg under the arterial values. When the transcutaneous CO2 values were compared with the arterial values, the correlation coefficient was 0.906. The mean transcutaneous pCO2 values measured lay around 0.7 mm Hg above the arterial values. On the basis of this slight deviation in CO2 values, the method appears to be suitable for continuous non-invasive determination of pCO2. The very large deviations in the O2 values indicate that transcutaneous measurement of oxygen partial pressure in this specific examination situation is not sufficiently reliable, which makes questionable the practice of using one piece of equipment for both measurements. In the clinical setting presented, transcutaneous O2 monitoring does not represent an alternative to close clinical observation and pulse oximetry.     

Die präoperative Evaluierung und Vorbereitung Die Sicht des Anästhesisten

Die Anaesthesiologie - Nicht zuletzt aus Kostengründen müssen auch die präoperativ veranlaßten Untersuchungen nach einem rationalen Konzept, adaptiert an das individuelle...     

Prolongierte Muskelschwäche des Intensivpatienten unter besonderer Berücksichtigung der sog. Intensiv-Polyneuromyopathie

Generalized muscle weakness in critically ill patients can result in prolonged periods of artificial ventilation and longer stays in the intensive care unit. Both neuropathic (critical illness polyneuropathy) and myopathic (critical illness myopathy) abnormalities seem to play an important role for this prolonged weakness. This article reviews its complex differential diagnosis with special emphasis on the current understanding of the neuromuscular syndromes. An efficient diagnostic plan is necessary for the exclusion of other curable causes of prolonged muscle weakness even in the presence of polyneuromyopathic changes. Psychological support of the patient and prophylaxis of secondary complications of prolonged immobilization are crucial when specific therapy is not possible.     

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Ohne Zusammenfassung     

Responsiveness of the cerebral circulation to acute alterations in mean arterial pressure during the administration of propofol

The responsiveness of the cerebral circulation to acute increases in mean arterial pressure was studied before and during the administration of propofol 3, 6, or 12 mg/kg/h in the anaesthetised baboon. Although mean arterial pressure increased significantly on each occasion, there were no significant changes in cerebral blood flow. This indicates that the physiological responsiveness of the cerebral circulation to alterations in mean arterial pressure was preserved during the administration of propofol in the concentrations studied.