Gerald Volker Dietrich

The use of an anesthesia information management system for prediction of antiemetic rescue treatment at the postanesthesia care unit.

We used an anesthesia information management system (AIMS) to devise a score for predicting antiemetic rescue treatment as an indicator for postoperative nausea and vomiting (PONV) in the postanesthesia care unit (PACU). Furthermore, we wanted to investigate whether data collected with an AIMS are suitable for comparable clinical investigations. Over a 3-yr period (January 1, 1997, to December 31, 1999), data sets of 27,626 patients who were admitted postoperatively to the PACU were recorded online by using the automated anesthesia record keeping system NarkoData® (IMESO GmbH, Hüttenberg, Germany). Ten patient-related, 5 operative, 15 anesthesia-related, and 4 postoperative variables were studied by using forward stepwise logistic regression. Not only can the probability of having PONV in the PACU be estimated from the 3 previously described patient-related (female gender, odds ratio [OR] = 2.45; smoker, OR = 0.53; and age, OR = 0.995) and one operative variables (duration of surgery, OR = 1.005), but 3 anesthesia-related variables (intraoperative use of opioids, OR = 4.18; use of N2O, OR = 2.24; and IV anesthesia with propofol, OR = 0.40) are predictive. In implementing an equation for risk calculation into the AIMS, the individual risk of PONV can be calculated automatically.

Increase of interleukin-6 plasma levels after elective craniotomy: Influence of interleukin-10 and catecholamines

SummaryAccidental and operative trauma are able to induce a systemic reaction of the organism characterized by fever, leukocytosis, catabolism, and an activation of the coagulation system. Interleukin-6 (IL-6) has been found to be an important mediator of this acute-phase response. In this study the influence of elective craniotomy on IL-6 plasma levels was evaluated. Blood samples were obtained from 20 patients undergoing elective craniotorny for vascular or tumorous diseases of the brain. IL-6 increased significantly (p < 0.05) from the pre-operative (0 (0–5.4) pg/ml) to the intraoperative (180 min after beginning of surgery) time-point (10.6 (0–18.5) pg/ml). The maximum was reached on the first postoperative morning (13.9 (4.3–45.0) pg/ml). Interleukin-10 (IL-10) is an anti-inflammatory cytokine which suppresses IL-6 synthesis in vitro in various cell lines. IL-10 plasma concentrations showed no alterations throughout the study period. Epinephrine plasma concentrations increased significantly from pre-operative values (15 (0–74) pg/ml) to the postoperative time-point (57 (9–459) pg/ml). A 4.5-fold increase (p < 0.05) of norepinephrine plasma concentrations was found when comparing the data obtained 60 min after beginning of surgery with the data of the first postoperative morning. In monocytes, which are a major source of plasma IL-6, an elevation of intracellular cAMP stimulates the IL-6 synthesis. The postoperative maximum of IL-6 in plasma could be due to a release of catecholamines. In conclusion this study demonstrated an elevation of IL-6 plasma concentrations during and after elective craniotomy. Increased plasma catecholamine concentrations as well as a damage in the blood-brain barrier due to the surgical trauma with a spill-over of IL-6 from brain tissue into plasma could have contributed to this result.

Platelet Function and Adrenoceptors during and after Induced Hypotension using Nitroprusside

Background Hypotension induced by sodium nitroprusside can minimize intraoperative blood loss. The release of endogenous catecholamines can influence adrenoceptors of platelets and thus might change the ability of platelets to aggregate. Methods Forty patients undergoing nasal septum, tympanoplastic, or sphenoid sinus surgery were randomly divided into two groups, those having controlled hypotension (A) and those serving as controls (B). Blood samples were drawn before the operation, after induction of anesthesia, 1 h after the start of the operation, and on the day after surgery. Results Epinephrine-induced platelet aggregation only increased in the controls on the day after surgery (A: from 49 +/- 25% to 47 +/- 29%; B: from 53 +/- 24% to 72 +/- 14%; mean +/- SD; P < 0.01). Spontaneous platelet aggregation increased in the controls from a median of 1.2 Ohm/h to 2.4 during the operation and 2.9 on the day after surgery but not after hypotension. On the day after surgery, alpha2 receptors reached their maximum (A: 238 +/- 164; B: 234 +/- 80 per platelet). During the operation, the norepinephrine concentrations were significantly greater in group A (median, 419 pg/ml) than in group B (median, 217 pg/ml; P < 0.05). Blood loss was greater in the controls (A: 180 +/- 75; B: 379 +/- 120 ml; P < 0.05). Conclusions Controlled hypotension using sodium nitroprusside reduces epinephrine-induced and spontaneous platelet aggregation. Even on the day after hypotension, the usual postoperative reactive increase in platelet aggregation did not occur. These results may be explained by the direct effect of nitroprusside on platelets, the augmented stress response, lower shear stress on platelets due to the lower blood pressure, or the decreased blood loss compared with the controls.

Indicators of Erythrocyte Damage after Microwave Warming of Packed Red Blood Cells

BACKGROUND Localized overheating of packed red blood cells (PRBCs) after microwave warming with consequent damage to erythrocytes has been reported. We therefore compared possible cellular markers of erythrocyte damage, as measured by flow cytometry, with laboratory indicators of hemolysis to evaluate the effects of microwave warming on PRBCs. METHODS PRBC samples were warmed to room temperature or to 37, 42, 47, 52, or 57 degrees C in a water bath. Flow cytometry was performed after fluorescein labeling using antibodies to spectrin, Ca(2+)-ATPase, and Na(+)-K(+)-ATPase. The forward-to-sideward scatter (FSC/SSC) ratio and antibody binding were evaluated. Plasma free hemoglobin (FHb) and alpha-hydroxybutyrate dehydrogenase (HBDH) were measured immediately after heating and after 48 h. In addition, all measurements were made before and after the heating of PRBCs to 35 degrees C by a microwave blood warmer. RESULTS Analysis of 15000 erythrocytes showed a decrease in the FSC/SSC ratio and antibody binding above 47 degrees C [at 37 degrees C, median (SD) of 94.2 (7.4) with 0.07 (0.05)% fluorescein-positive; at 52 degrees C, median (SD) of 177.0 (19.0) with 18.5 (6.4)% positively gated; P <0.001]. FHb [room temperature, 0.3 (0.2) g/L] was increased 2-fold at 37 and 42 degrees C, 4-fold at 47 degrees C, and 25-fold at 52 degrees C. HBDH increased in parallel. Hemolysis markers showed an additional twofold increase 48 h after heating to 42 and 47 degrees C. Microwave heating to 35 degrees C did not produce significant changes of any marker. CONCLUSIONS All markers of cellular damage were altered after heating to >47 degrees C, and a substantial part of hemolysis was delayed. The methodology can be used for future testing of other blood warming devices.

Temperature course and distribution during plasma heating with a microwave device.

Summary In spite of the much shorter thawing times, the use of microwave devices for heating units of fresh frozen plasma is still being discussed. Concerns about general and localised overheating are the main arguments against the use of microwave devices. We evaluated the warming of fresh frozen plasma using the recently introduced Transfusio‐therm 2000® microwave blood warmer. Units of fresh frozen plasma were weighed and the heating times were recorded. The surface temperature of the fresh frozen plasma bags during heating was recorded every 10 s. Temperature variation on the surface was examined by measuring the difference between peripheral and centrally placed temperature sensors. After heating, plasma temperature was determined using a calibrated thermometer. There were no signs of overheating during the heating process. The surface temperature of three units of fresh frozen plasma heated simultaneously (n = 45) was 34.0°C (SD, 1.5°C) after a mean heating time of 23.2 min (SD, 1.1 min). The mean (SD) temperature difference was −0.6 (0.5)°C and the mean (SD) plasma temperature was 33.6 (0.8)°C. Heating one fresh frozen plasma unit at a time (n = 20), the mean (SD) heating time was 6.3 (0.4) min. The surface temperature after heating was 34.3 (0.2)°C, the mean (SD) temperature difference was −0.6 (0.4)°C and the mean (SD) plasma temperature after heating 33.1 (0.6)°C. We conclude that no general or localised overheating of fresh frozen plasma occurs during or after heating with the microwave blood warmer.

What the neurosurgeon needs to know about the coagulation system

Intracranial surgery is often complicated by thromboembolic events including the life-threatening pulmonary embolism. After head trauma and in patients with brain tumors disseminated intravascular coagulation (DIC) can occur, characterized by the triggering of the coagulation cascade and the depletion of coagulation factors which ultimately leads to bleeding. The identification of patients at high risk as well as the early diagnosis of hemostatic problems uses routine laboratory parameters such as partial thromboplastin time and prothrombin time reflecting the intrinsic and the extrinsic pathway of the coagulation respectively. Thrombin antithrombin III complexes (TAT) and prothrombin fragment 1 + 2 (F1 + 2) are further indicators of an activation of the coagulation whereas fibrinogen degradation products (FDP) refer to the fibrinolytic system. The basic principles of coagulation and fibrinolysis are summarized as well as the changes of laboratory parameters accompanying DIC, hypercoagulability and hyperfibrinolysis.

Untersuchung über den in vitro Einfluß von α2-Agonisten auf die Thrombozytenfunktion und Dichte thrombozytärer α2-Rezeptoren

ZusammenfassungThrombozyten tragen α2-Rezeptoren auf der Zelloberfläche, deren Stimulation die Thrombozytenaggregation auslöst. Die vorliegende Untersuchung ging der Frage nach, ob α2-Agonisten die Dichte thrombozytärer α2-Rezeptoren vermindern und hierüber die Thrombozytenaggregation beeinträchtigen. Venöse Blutproben von 20 gesunden Probanden wurden über 24 h in vitro mit Clonidin und Dexmedetomidin inkubiert. Die Epinephrin- und Kollagen-induzierte Thrombozytenaggregation wurde mit Hilfe der Turbidometrie und die Dichte der thrombozytären α2-Rezeptoren in Radioliganden-Bindungsstudien mit3H-Yohimbin gemessen. Die klinisch relevanten Konzentrationen von 1 ng/ml Clonidin bzw. Dexmedetomidin führten zu keinen signifikanten Veränderungen der Thrombozytenaggregation oder der α2-Rezeptoren-Dichte. 10 ng/ml Dexmedetomidin verursachten eine signifikante (p<0,05) Abnahme der Epinephrin-induzierten Thrombozytenaggregation (16,0±5,4%, n=20, Mittelwert±SEM) verglichen mit der Kontrollprobe (46,0±1,3%, n=20). Für die α2-Rezeptorendichte ergaben sich keine signifikanten Unterschiede zur Kontrollprobe. Dieses Ergebnis zeigte, daß eine Desensitivierung der Epinephrin-induzierten Thrombozytenaggregation ohne quantitative Veränderung der α2-Rezeptoren auftreten kann.Abstractα2-Agonists are being used increasingly in anaesthesia and intensive care medicine because of their antihypertensive, analgesic and sedative properties. Platelets bear α2-receptors on the cell surface. Stimulation of these receptors by agonists induces platelet aggregation. The present study examined whether in vitro incubation of blood with the α2-agonists clonidine and dexmedetomidine decreases α2-receptor density and hereby influences platelet aggregation. Methods. Whole blood of 20 healthy volunteers was incubated over 24 h at 37° C with 1 ng/ml clonidine or 1 or 10 ng/ml dexmedetomidine. Induced platelet aggregation was determined by means of turbidometry. Epinephrine (22 μmol/l) or collagen (20 mg/l) served as inductors. The density of α2-receptors was measured in radioligand assays with 3H-Yohimbine. Phentolamine was used to assess unspecific binding. The data were analyzed with an analysis of variance. Results. Neither 1 ng/ml clonidine nor 1 ng/ml dexmedetomidine altered platelet aggregation or α2-receptor density in comparison with the control sample. As a major result we found that 10 ng/ml dexmedetomidine caused a significant (P<0.05) reduction in epinephrine-induced platelet aggregation (16.0± 5.4%, n=20, mean±SEM) compared with the control (46.0±1.3%, n=20). α2-Receptor density was not any different from the control. Conclusions. This in vitro study showed that clinically relevant concentrations of 1 ng/ml clonidine or dexmedetomidine did not alter platelet aggregation or α2-receptor density, even after 24 h exposure. However, 10 ng/ml dexmedetomidine was found to diminish significantly epinephrine-induced platelet aggregation, but did not change α2-receptor density. This result showed that desensitization of platelet aggregation can occur without quantitative changes in α2-receptors.

Risikofaktoren und Häufigkeiten von Nebenwirkungen bei autologen Blutentnahmen

ZusammenfassungFragestellung: Autologe Blutentnahmen vor elektiven, chirurgischen Eingriffen helfen das perioperative Risiko zu vermindern, können aber selbst Nebenwirkungen auslösen. Gibt es besondere Patientenmerkmale, die die Häufigkeit und den Schweregrad unerwünschter Ereignisse beeinflussen? Methodik: Offene prospektive Untersuchung bei 3603 autologen Blutentnahmen mit der Erfassung von Alter, Geschlecht, Größe, Gewicht, Vorerkrankungen des Patienten, Eingriff, Art der Entnahme (Eigenblutspende oder Plasmapherese) und des jeweiligen Risikoscores nach Böcker. Die beobachteten Nebenwirkungen wurden in Schweregrade eingeteilt und mit den erfaßten Parametern ausgewertet. Die Untersuchung erfolgte im Bereich Eigenblutspende der Abteilung Anaesthesiologie und Operative Intensivmedizin einer Universitätsklinik. Es wurden 1041 Patienten im Zeitraum vom 1. Januar 1995 bis 1. April 1997 untersucht, die sich einer präoperativen, autologen Blutentnahme unterzogen. Ergebnisse: Bei 7,4% der Patienten traten Nebenwirkungen auf. Hypotension und Bradykardie waren am häufigsten vertreten. 4,3% der Nebenwirkungen wurden als Schweregrad (SG) 1 (minimal), 2,4% als SG 2 (leicht) und 0,7% als SG 3 (mäßig) eingestuft. Die Häufigkeit von Nebenwirkungen war lediglich in der Gruppe der Patienten unter 25 Jahren erhöht. Für alle übrigen untersuchten Merkmale, einschließlich hohem Alter, kardialen oder pulmonalen Vorerkrankungen und hohem Risikoscore ließ sich kein erhöhtes Spenderisiko feststellen. Schlußfolgerungen: Nebenwirkungen bei autologer Blutentnahme sind seltene Ereignisse. Prädiktor für mögliche Nebenwirkungen ist niedriges Lebensalter (<25 Jahren). Bezüglich der anderen untersuchten Parameter und Risikofaktoren ist der Vorhersagewert gering. Somit benötigen alle Patienten zur autologen Blutentnahme gleichermaßen eine ärztliche Überwachung. Unter diesen Voraussetzungen kann selbst bei Patienten mit schweren Begleiterkrankungen die Eigenblutentnahme als sicheres Verfahren gelten.AbstractObjective: Autologous blood donation before elective surgery decreases the perioperative risk although donation itself can cause adverse effects. Are there specific donor characteristics, which influence the frequency and severity of adverse effects? Methods: We investigated in a prospective study 3603 autologous blood donations including registration of patient’s age, gender, height, weight, medical record and risk-score by Böcker. The adverse effects were divided into severity groups (SG). The Investigation took place in a Department of Anaesthesiology and Intensive Care Medicine in an university hospital. 1041 patients with preoperative autologous blood donation were in-vestigated between January 1995 and April 1997. Results: 7.4% of patients had adverse effects. Hypotension and bradycardia were the most frequent adverse effects. 4.3% of the adverse effects were graded as minimal (SG 1), 2.4% as mild (SG 2) and 0.7% as moderate (SG 3). The rate was higher in young donors (<25 years). For all other donor characteristics including older age, cardiac or pulmonary diseases and high risk-score no higher donation risk was observed. Conclusions: Adverse effects during and after autologous blood donation are rare. Predictor for reaction seems to be young age (<25 years). Referring to donor’s characteristics and predonation risk factors it is hardly possible to predict adverse effects. Thus, all autologous blood donors require adequate monitoring by a physician. Under these circumstances the autologous blood donation is a safe procedure, even in patients with severe risk factors.

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.

Beta 2-adrenoceptor density of human lymphocytes after nitroprusside-induced hypotension.

The present study was undertaken to assess the influence of nitroprusside-induced hypotension on beta2-adrenoceptor density. Twenty-four patients undergoing noseseptum corrections under general anesthesia were allocated randomly to a nitroprusside or control group. beta2-Receptor density on lymphocytes was measured by binding studies using (-)125 I-iodocyanopindolol. Lymphocyte subpopulations B, T, T (helper), Tsuppressor, and natural killer cells were determined simultaneously by flow cytometry. Five of 12 nitroprusside-treated patients developed significant intraoperative increases of epinephrine levels (+ 69% versus preoperatively) which were not seen in the remaining seven patients. In these five patients, beta2-receptor density of unfractionated lymphocytes was 26% lower (P < 0.05) on the first day after surgery compared with preoperative values. Since no changes in proportions of lymphocyte subpopulations were observed, these results are not caused by redistribution phenomena inducing a decrease of subsets with a high number of beta receptors. These findings suggest that beta2-adrenergic responsiveness might be diminished after nitroprusside treatment in some patients. (Anesth Analg 1995;81:1250-4)