A. Sablotzki

Plasma levels of immunoinhibitory cytokines interleukin-10 and transforming growth factor-beta in patients undergoing coronary artery bypass grafting.

OBJECTIVEnCardiovascular surgery with extracorporeal circulation causes a systemic inflammatory response, which can lead to organ failure and increased postoperative morbidity. Advances in knowledge about the interactions between markers of cellular and humoral immunity involved in the inflammatory response to cardiopulmonary bypass (CPB) may reduce the deleterious effects and improve the outcome for patients undergoing cardiac surgery.nnnMETHODSnTo determine the release of immunoinhibiting cytokines during CPB, we measured plasma levels of interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta) in 30 patients undergoing elective coronary artery bypass grafting. Arterial blood samples were collected at eight time points before, during and after CPB, using a standardized ELISA-technique.nnnRESULTSnPlasma IL-10 and TGF-beta increased significantly after weaning off CPB (P < 0.05) and peaked respectively at time of skin closure (IL-10, 308 +/- 180 pg/ml; TGF-beta, 1860 +/- 906 pg/ml; mean peak +/-S.D.). Postoperatively, 6 h, IL-10 decreased to 19.8 +/- 9.8 pg/ml (P < 0.05) and TGF-beta decreased to 1133 +/- 547 pg/ml (P < 0.05).nnnCONCLUSIONSnBoth cytokines are major immunoregulatory factors with negative influence on T cell-mediated immunologic response. The significantly elevated levels at the end of CPB indicate that IL-10 and TGF-beta may be important factors of immunologic dysregulation following CPB.

Quantitative determination of free intracellular amino acids in single human polymorphonuclear leucocytes. Recent developments in sample preparation and high-performance liquid chromatography

The described procedure allows quantitative, highly precise and reproducible analysis of free amino acid concentrations in single polymorphonuclear leucocytes (PMLs). This method is superior to previously described procedures with regard to sample size, PML separation, sample preparation and stability, as well as the chosen fluorescence high-performance liquid chromatography procedure, and can satisfy the high demands for ultra-sensitive and comprehensive amino acid analysis, especially for the continuous surveillance of severe diseases and organ dysfunction.

[Tamm-Horsfall protein, alpha-1- and beta-2-microglobulin as kidney function markers in heart surgery].

ZusammenfassungOperationen am offenen Herzen gehen in bis zu 4% der Fälle mit zeitweiligen Nierenfunktionsstörungen einher. Eine Lokalisation der Schädigung ist nur invasiv mit der Feinnadelbiopsie möglich. Die Ausscheidung des Nierentubulusproteins Tamm-Horsfall (THP) und der Mikroglobuline α-1 (α-1 MG) und β-2 (β-2 MG) wurden bei insgesamt 30 Patienten untersucht. Eine Einteilung in 2u2005Gruppen erfolgte nach der präoperativen Kreatinin-Clearance (ClKrea). Alle Patienten wurden vor und bis zum 2.u2005Tag postoperativ beobachtet. Die Gruppe der präoperativ Nierengesunden umfaßte 15 Patienten (13u2005m/2u2005w, Diagnosen: 14mal ACB, 3mal Klappenersatz). Das THP zeigte einen gleichbleibenden Verlauf mit einer Korrelation von 0,7 zur ClKrea (p<0,001). α-1 MG aus dem spätdistalen Tubulus wies parallele Veränderungen auf. Bei β-2 MG wurden trotz Schwankungen eine deutliche Entwicklung zu pathologischen Werten postoperativ und eine hohe Korrelation zum α-1-MG gefunden (r= 0,76; p<0,0001). Die Gruppeu2005II umfaßte ebenfalls 15 Patienten (13u2005m/2u2005w, Diagnosen: 9mal ACB, 4mal Klappenersatz, 4mal Kombinationseingriffe, 1mal HTX). Parallel zur ClKrea verhielt sich auch in dieser Gruppe der Verlauf des THP. α-1- und β-2-MG stiegen von 32,8 (0,73)u2005mg als leicht pathologische Werte als Zeichen einer massiven tubulären Schädigung postoperativ stark an. Hier konnte gezeigt werden, daß Operationen am offenen Herzen häufig transiente Nierenfunktionsstörungen verursachen, besonders bei vorbestehenden Schäden. Außerdem wurde gezeigt, daß mit empfindlichen Parametern tubuläre und glomeruläre Schäden verifiziert werden können.AbstractAfter cardiac surgery, transient renal dysfunction often occurs. Regional differentiation of these processes is possible only using invasive techniques, including renal biopsy. Approximately 30u2005different plasma protein components have been identified in the urine of healthy individuals by means of qualitative and quantitative immunochemical methods. The detection of microalbuminuria has high diagnostic relevance for the early diagnosis of renal damage at a reversible stage. One typical urinary protein is Tamm-Horsfall protein (THp). After histochemical staining of human kidney sections, activity is seen in the loop of Henle and initial distal tubule. The assay of α-1 microglobulin (MG) in urine is considered one of the most efficient laboratory parameters for the diagnosis of tubular lesions. Serum concentrations of α-1 MG are less dependent on extrarenal changes than are those of other low-molecular-weight proteins. β-2 MG is also one of the standards used in recent years for diagnostic relevance. Urinary albumin excretion, normaly less than 30u2005mg per day, sometimes increases after glomerular damage. Some renal function tests are used daily in many intensive care units, e.g. creatinine clearance (CCr) or urea and sodium excretion. Renal dysfunction should, however, be further examined to localise regional damage and to seek new clinical standards in addition to the conventional tests.nn Methods. After obtaining the agreement of the local ethics committee, 30u2005patients were divided into two groups of 15 each: groupu2005I without renal dysfunction and CCr more than 60u2005ml/min; and groupu2005II with CCr below 60u2005ml/min. THp and α-1 MG were measured pre- and postoperatively after open heart surgery with the ELISA and β-2 MG with the nephelometric technique. These parameters were compared with clinical standards such as albumin excretion, blood urea nitrogen (BUN), urea clearance, and fractional sodium excretion.nn Results. The CCr did not change in groupu2005I from the pre- to postoperative period (81.5 to 85.1 and 91.4u2005ml/min), nor did excretion of THp (20.1 to 25.0 and 24.8u2005mg/day), correlation r=0.7; P<0.001). The elimination of α-1 and β-2 MG was significantly higher in the postoperative period in this group (α-1: 7.2 to 44.1 and 100.6u2005mg/day; β-2: 0.3 to 2.1 and 3.2u2005mg/day). In groupu2005II CCr showed pathological values (36.8 to 31.1 and 36.3u2005ml/min), as did simultaneous THp (13.5 to 9.7 and 12.7u2005mg/day). α-1 and β-2 MG values became more pathological in the postoperative period than in groupu2005I (α-1: 32.8 to 113.9 and 198.5u2005mg/day; β-2: 0.7 to 5.8 and 16.9u2005mg/day).nn Discussion. Measurement of the excretion of THp and α-1 and β-2 MG is a useful addition to present clinical standards for recognising early changes in renal function. The increases in the postoperative period after cardiac surgery showed tubular damage even in patients without predictive risk factors or clinical signs. In patients with renal dysfunction open heart surgery and extracorporeal circulation led to significant tubular damage.

Dysregulation of immune response following neurosurgical operations.

Background: Postoperative infections are common and potentially fatal complications in neurosurgical intensive care medicine. An impairment of immune function has been described after central nervous system surgery and in patients harboring malignant brain tumors. The aim of our study was to investigate whether differences in cell‐mediated immunity can be found in patients undergoing craniotomy for surgery of glioblastoma or clipping of an intracerebral aneurysm.

Impairment of renal function after cardiopulmonary bypass is not influenced by dopexamine.

Introduction: The objective of this study was to evaluate the effects of dopexamine on renal function in 4 groups of patients either with or without renal dysfunction. Transient renal dysfunction is often not clinically relevant in patients with normal renal function, but it is an important clinical factor in patients with pre-existing renal failure. Dopexamine (DX) is a commonly used catecholamine which probably exerts a selective effect at the splanchnic bed. Material and Methods: 24 patients with normal renal function and 24 patients with impaired renal function (creatinine in serum ≥ 1.5 mg/dL) were each randomly allocated to 2 groups. Group 1 (control) without renal dysfunction and group 3 (control/dysfunction) with renal dysfunction were considered as control groups, while the patients in DX and DX/dysfunction groups received 1 μg/kg/min dopexamine until the end of surgery. Kidney function was investigated using standard parameters and by investigating specific proteins and enzymes. Results: All patients showed pathologic excretions of the investigated parameters during cardiopulmonary bypass (CPB) with no differences between the study groups. The distal tubule, the lysosomal regions, Henles loop and the glomerular tuft were all damaged. Heart rate and cardiac index increased significantly in the DX-groups, first until the end of surgery, second until the start of ECC. Conclusion: Dopexamine at a dose of 1 μg/kg/min had no influence on renal function and protein excretion and cannot be regarded as a kidney function protecting substance.

Cerebral blood flow velocity during isovolemic hemodilution and subsequent autologous blood retransfusion.

PurposeTo quantify the influence of hematocrit on cerebral blood flow velocity (CBFV) in healthy volunteers undergoing acute isovolemic hemodilution (HD) with hydroxyethyl starch 10% (HES) and subsequent autologous whole blood retransfusion (RT).MethodsIn 11 volunteers 20 ml · kg−1 blood was withdrawn over 30 min and simultaneously replaced with HES 10%. Thirty min later, RT was started at a constant rate over 30 min. Recorded parameters included: CBFV pulsatility-index (Pl) and resistance-index (Rl) of the middle cerebral artery (MCA). Blood pressure (BP), heart rate (HR), hemoglobin (Hb), hematocrit (Hc) peripheral O2-saturation (SpO2), PET · CO2, arterial oxygen content (CaO2) and cerebral arterial O2 -transport (CE-DO2= CaO2 × Vm-MCA) were monitored.ResultsAn average of 1570 total blood was withdrawn which resulted in a decrease in Hb from 14.5 mg · dl−1 to 10.3 mg · dl−1; He (and CaO2) decreased from 41.8 % (19.8 ml · dl−1) to 29.6% (14.2 ml · dl−1;P < 0.01). Vm-MCA increased from 61.2 cm · sec−1 to 77.3 cm · sec−1 (P < 0.01). Following RT Vm-MCA decreased again, but remained higher than baseline (P < 0.01). PI decreased by 13% following RT (P < 0.05), There were no changes in RI, HR, BP, SpO2 and PETCO2. Regression lines could be fitted between He and Vm-MCA, Vm-MCA and CaO2 and between He and CEDO2.ConclusionsTranscranial Doppler changes in blood flow velocities correlated with the simultaneously recorded systemic He and CaO2 values. We found a 2% increase in CBFV for each 1 % decrease in He and CaO2.RésuméObjectifQuantifier l’influence de l’hématocrite sur la vitesse du flux sanguin cérébral (VFSC) chez des volontaires en santé qui subissent une hémodilution isovolémique aiguë (HD) avec de l’amidon hydroxyéthyle 10% (AHE) et une retransfusion (RT) de sang autologue complet.MéthodeOn a prélevé 20 ml · kg−1 de sang chez 11 volontaires pendant 30 min et on l’a remplacé simultanément par de l’AHE 10%. Trente minutes plus tard, on a amorcé la RT à vitesse constante pendant 30 min. Les paramètres enregistrés comprennent: VFSC, l’indice de pulsatilité (IP) et l’indice de résistance (IR) de l’artère cérébrale moyenne (ACM). La tension artérielle (TA), la fréquence cardiaque (FC), l’hémoglobine (Hb), l’hématocrite (Ht), la saturation en O2 du sang périphérique (SpO2), la PETCO2, la concentration en oxygène du sang artériel (CaO2) et le transport d’O2 artériel cérébral (CE-DO2= CaO2 × Vm-ACM) ont été mesurés.RésultatsEnviron 1570 ml de sang total ont été prélevés, ce qui a provoqué une hausse de l’Hb de 14,5 mg · dl−1 à 10,3 mg · dl−1; l’Ht (et la CaO2) ont diminué de 41,8 % (19,8 ml · dl−1) à 29,6 % (14,2 ml · dl−1;P < 0,01). Vm-ACM a augmenté de 61,2 cm · sec−1 à 77,3 cm · sec−1 (P < 0,01). Après la RT Vm-ACM a subi une autre baisse, mais est demeuré plus haut que la donnée de base (P < 0,01). LIP a diminué de 13 % après la RT (P < 0,05). Il n’y a pas eu de changement d’IR, FC, TA, SpO2 et PETCO2. Les courbes de régression se situaient entre Ht et Vm-ACM, Vm-ACM et CaO2 et entre Ht et CEDO2.ConclusionLes changements au Doppler transcrânien des vitesses du flux sanguin correspondent aux enregistrements simultanés de l’Ht générale et des valeurs de CaO2. Nous avons noté une augmentation de VFSC de 2% pour chaque baisse d’Hc et de CaO2 de 1%.

Concentration of cefamandole in plasma and tissues of patients undergoing cardiac surgery: the influence of different cefamandole dosage.

OBJECTIVEnTo develop an improved regimen of antibiotic prophylaxis in cardiac surgery, three antibiotic prophylactic regimens for patients scheduled to have elective cardiothoracic surgery involving a median sternotomy were evaluated.nnnDESIGNnA prospective, randomized, unblinded study.nnnSETTINGnA university teaching hospital.nnnPARTICIPANTSnSixty-nine men scheduled for elective coronary artery bypass grafting (CABG) with extracorporeal circulation (ECC) were included in the study.nnnINTERVENTIONSnThe patients were selected at random to receive 2 g of cefamandole (CM) at induction of anesthesia (group 1, n = 24), or 2 g of CM at the beginning of anesthesia followed by an additional dose (2 g) immediately after onset of cardiopulmonary bypass (CPB) (group 2, n = 22), or 4 g of CM just at the initiation of anesthesia (group 3, n = 23). Samples from the mammary artery, sternum, and plasma were obtained at various intervals after injection of the antibiotic (10 minutes intravenously) to compare antibiotic levels, assayed for CM concentrations, with high-pressure liquid chromatography (HPLC) and plasma bactericidal activity as well as infectious complications in these sites as a function of time for the three groups.nnnMEASUREMENTS AND MAIN RESULTSnThere were no significant differences in biometric data, duration of hospitalization, or management of cardiopulmonary bypass, including urinary tract drainage and infusion volume. The mean plasma t1/2 (distributive or alpha-phase) before bypass was 51.7 +/- 16.7 minutes for group 1 and 2 patients and 54.9 +/- 15.9 minutes for group 3 patients. CM plasma values were significantly higher in group 2 (170.3 +/- 105.8 micrograms/mL) than in groups 1 and 3 (111.8 +/- 42.2 micrograms/mL, 101.2 +/- 57.2 micrograms/mL) at the end of bypass periods (p < 0.05). The antibiotic contents of mammary artery and sternum samples of group 2 (15.6 +/- 4.7 micrograms/mL, 9.5 +/- 4.7 micrograms/mL) were significantly higher after completion of CPB compared with group 1 (5.7 +/- 1.9 micrograms/mL, 3.8 +/- 2.9 micrograms/mL) and group 3 (6.3 +/- 3.5 micrograms/mL, 3.6 +/- 1.8 micrograms/mL) (p < 0.05). There were no significant differences in distribution of micro-organisms among the three groups, but two patients of groups 1 and 3 with plasma and tissue CM levels below minimal inhibitor concentration (MIC90) for Hemophilus influencea, E coli, Proteus ssp and Klebsiella ssp after completion of CPB, respectively, developed a pneumonia postoperatively caused by Hemophilus influencea (1), E coli (1) and Klebsiella ssp (2) (p < 0.05).nnnCONCLUSIONSnIt would be preferable to infuse the antibiotic shortly before the operative procedure. However, to keep tissue and plasma CM values more than MIC90 for common pathogens during the time period studied, a second infusion of 2 g of CM administered after onset of CPB suggests better protection against the risk of microbial infections. Therefore, the findings might be important for the choice of antibiotic prophylaxis, particularly for high-risk patients.

Akutes Nierenversagen Noninvasive Frühdiagnostik des akuten Nierenversagens bei operativen Intensiv-patienten*

ZusammenfassungBei 21 Patienten der Operativen Intensivstation wurden an 5 aufeinanderfolgenden Tagen tubuläre und glomeruläre Proteine und Enzyme, die Messung der glomerulären Filtrationsrate und des renalen Plasmaflusses sowie die in der klinischen Routine durchgeführten Bestimmungen der Retentionsstoffe Kreatinin und Harnstoff untersucht. 7 dieser Patienten wurden während der letzten 5 Tage vor Beginn eines akuten Nierenversagens erfaßt und mit einer Kontrollgruppe verglichen. Es konnte mit hoher Wahrscheinlichkeit ein zirkulatorisches Nierenversagen bei den 7 Patienten mit fast gleichzeitigem Untergang tubulärer und glomerulärer Strukturen und Funktionen festgestellt werden. α-1 Mikroglobulin, Angiotensinase A, Tamm-Horsfall-Protein, die PAH-Clearance und die FeNa zeigten 2 bis 3 Tage vor dem Abfall der Kreatininclearance und dem Anstieg des Serumkreatinins und -harnstoffs pathologische Werte. Anhand der Sensitivität und Spezifität der Tests bezüglich der Diagnose „Akutes Nierenversagen” werden diese Ergebnisse mit Literaturangaben verglichen.AbstractAcute renal failure is a common and severe complication in ICU. Renal laboratory examinations like creatinine and urea are late signs of renal dysfunction: Most of the functional abilities are reduced and there is no time for therapeutical interventions. The aim of this study was to find some earlier sensitive parameters of renal dysfunction and the order of appearance, the cause of acute renal failure and the value of the measured parameters.nn Methods: After agreement of the local ethic committe, 21 patients of the ICU were investigated. They were devided into two groups: 1st (n=14) with no signs of renal dysfunction and were regarded as control group and 2nd (n=7) were examined until the beginning of acute renal failure. For five days the glomerular filtration rate, proteinuria (immunglobulin G, Tamm-Horsfall protein, α-1- and β-2 microglobulin, lysozyme), the brush border enzymes angiotensinase A and the lysosomal enzyme N-acetyl-β-d-glucosaminidase were daily measured and compared with clinical standards like the excretion of albumin, the clearances of creatinine and urea and the fractional excretion of sodium.nn Results: Both groups were comparable with respect to drug therapy, APACHE-II-score (with the exception of the last day before ARF), and infusion therapy. There were differences in tubular functions between the 2 groups. Patients developing renal insufficiency showed an increased excretion of a-1-microglobulin, and decreased excretions of Tamm-Horsfall-protein, angiotensinase A as well as a low renal blood flow. Significant differences were also detectable in glomerular functions (glomerular filtration rate), albumin, and immunoglobulin G.nn Discussion: Only a short time intervall (1 to 2 days) between tubular and glomerular damage were detectable in patients with renal insufficiency. Renal failure must be due to circulatory problems because of the nearly simultaneous increase of tubular and glomerular parameters after RPF decreased. The parameters α1-microglobulin, angiotensinase A and Tamm-Horsfall-protein gave early indications for the acute renal failure. They showed satisfactory sensitivity and specifity, but the positive predictive value was poor.

Effects of etomidate on free intracellular amino acid concentrations in polymorphonuclear leucocytes in vitro

Background: Previous studies have shown the inhibitory effects of etomidate on polymorphonuclear leucocyte (PMN) function. No reports exist, however, regarding free intracellular amino acid metabolism, although physiological cell metabolism and basic cell functions rely upon a balanced intracellular amino acid content and the cell membrane‐mediated separation of cellular amino acids from the extracellular plasma amino acid pool. Thus, in the current study, we evaluated the effects of etomidate on free intracellular amino acid metabolism in PMN.

Perfusionsveränderungen bei Hämodilution Einfluß einer ausgedehnten isovolämischen Hämodilution mit Gelatine- und Hydroxyethylstärkelösungen auf die zerebrale Blutflußgeschwindigkeit und die kutane Mikrozirkulation beim Menschen

ZusammenfassungHintergrund: Ziel dieser Untersuchung war, den Einfluß einer ausgedehnten isovolämischen Hämodilution (NH) mit differenten kolloidalen Lösungen auf die Parameter der transkraniellen Dopplersonographie (TCD) und der kutanen Laser-Doppler-Flußmessung an wachen, unprämedizierten Probanden vergleichend zu quantifizieren. Methode: Der Blutverlust (20 ml/kg KG) wurde bei 7 Probanden randomisiert in 2 Sitzungen über einen Zeitraum von 30 min durchgeführt. Als isovolämischer Ersatz dienten Hydroxyethylstärke 6% (HES, 200000/0,5) bzw. eine 3%ige Gelatinelösung (GEL). 30 min später wurde das autologe Blut wiederum über einen Zeitraum von 30 min retransfundiert (RT). Ergebnisse: Eine NH mit einem durchschnittlichen Entnahmevolumen von 1498±85 ml (HES) und 1493±95 ml (GEL) induzierte Hämatokritreduktionen (Hk) von 40,9% auf 29,0% (HES) bzw. 39,8% auf 30,0% (GEL). Unter RT stiegen die Hk-Werte kontinuierlich an, blieben jedoch mit 34,2% (HES) und 34,5% (GEL) unter den Ausgangswerten. Der systemische Blutdruck sowie die Herzfrequenz waren insgesamt nicht verändert bzw. gruppendifferent. Die mittlere Blutflußgeschwindigkeit (Vm-MCA) stieg unter NH um 26% (HES) und 21% (GEL) linear an, fiel unter RT kontinuierlich ab und blieb nur in der HES-Gruppe (14%) auf einem gegenüber den Ausgangswerten höheren Niveau (3%, GEL). In Folge der NH kam es in der HES-Gruppe zu Anstiegen des kutanen Laser-Doppler-Flux (FLUX) und der mittleren Zellgeschwindigkeit (SPEED) um 61% und 38%. Nach RT lagen diese Parameter noch ca. 21% und 13% über den Ausgangswerten. Zu signifikant unterschiedlichen Effekten kam es in der GEL-Gruppe: Der FLUX bzw. der SPEED stiegen unter NH überdimensional um 291% und 114% an und zeigten unter RT eine derartige Abnahme, daß nach RT die Ergebnisse um 39% und 27% unter den Ausgangswerten lagen. Schlußfolgerung: Die gewonnenen Ergebnisse zeigen sowohl für HES wie auch für GEL eine enge inverse Korrelation der Blutflußgeschwindigkeitsveränderungen in der MCA mit den hämodilutions- und retransfusionsbedingten Änderungen bei systemischen Hämoglobin- und Hämatokritwerten. In der kutanen Mikrozirkulation kam es demgegenüber in beiden Untersuchungsgruppen zu überproportionalen bzw. nicht linearen Veränderungen und speziell dabei in der GEL-Gruppe zu extremen PerfusionsdifferenzenAbstractObjective: Quantifying the influence of extreme isovolemic hemodilution (NH) with different colloids on cerebral blood flow velocities (transcranial Doppler sonography) and cutaneous microcirculatory blood flow (laser Doppler flowmetry) in healthy, non-premedicated volunteers was the aim of this study. Methods: In seven volunteers (randomized cross-over design) 20 ml/kg blood was withdrawn within 30 min and simultaneously replaced with 6% hydroxyethyl starch (200000/0.5, HES) or 3% gelatin (GEL). Thirty minutes later, the autologous blood was retransfused (RT) within 30 min. Due to a severe allergic reaction to gelatin in one volunteer, only 6 GEL-NH were evaluated. Recorded parameters were: mean blood flow velocities (Vm-MCA) as well as the pulsatility index (PI) and the resistance index (RI) over the middle cerebral artery. In addition laser Doppler flux (FLUX), cell velocity (SPEED), mean arterial pressure (MAP), heart rate (HR), hemoglobin (Hb) and hematocrit (Hc) were monitored. Results: NH resulted in a withdrawal volume of 1498±85 ml (HES) and 1493±95 ml (GEL), (mean±SD) and induced a decrease in hemoglobin from 40.9 to 29.0% (HES) and from 39.8 to 30.0% (GEL). RT increased Hc to 34.2% (HES) and 34.5% (GEL). MAP and HR showed no significant alterations in both groups. Following NH, Vm-MCA rose almost the same way in either case (26% HES), 21% (GEL), but decreased continuously again during RT. After completing RT, only in the HES group Vm-MCA still remained higher than baseline values (14% HES, only 3% GEL). Similar inverse regression lines were found for the two groups between Hc and Vm-MCA: [Vm-MCAHES (cm/s)=−1.27×Hc+110.9; r=0.98, P<0.001 and Vm-MCAGEL (cm/s)= −1.32×Hc+110.9; r=0.91, P<0.001]. Furthermore, as a result of NH, FLUX and SPEED increased about 61% and 38% in the HES group and remained on higher values in comparison with starting positions (21% FLUX, 13% SPEED). However, the results in the GEL group were of a different kind: FLUX and SPEED increased stupendously to 291% and 114% combined with NH, but both were reduced by RT on a large scale (39 and 27% below baseline values). Whereas RI showed no group differences, there was a remarkable drop in PI during RT (17% HES, 12% GEL). Conclusion: The two plasma expanders studied show a close inverse correlation between the alterations of blood flow velocities in the middle cerebral artery and systemic hemoglobin and hematocrit values. In both groups the change in blood flow velocities is comparable. For the first time the results of relative changes in blood flow velocities following hemodilution and retransfusion in healthy volunteers are described that correspond closely by relative cerebral blood flow alterations found in animal studies as well. Moreover, a non-linear correlation of cutaneous microcirculation was shown by means of HES, but also by GEL. Obviously, there was the GEL group to be responsible for pronounced differences in cutaneous circulation.