Search PubMed⌕ Search

Biomedical subjects

R Scherer

Publications and source records attributed to R Scherer.

At least 37 records · Page 2Linked to original sources
PubMed1996

[Integrated concept for implementing clinical training in emergency medicine].

Since 1993 special lectures in emergency medicine are part of curriculum in the study of medicine at German universities. To intensify practical teaching in this field an integrative concept was followed in performing emergency training, the experiences of which are described in this paper. Seminars dealing with the most important subjects of preclinical care were combined with practical training blocks such as attendance at operations of the preclinical emergency physician service, resuscitation training using computerised resuscitation models (Mega Code), and an anatomical training course for endotracheal intubation, coniotomy, thoracic drainage, or central venous catheterisation on a corpse. If supported by physicians, senior students may supervise groups of 4 to 5 students during the Mega Code training in a tutorial system, thus allowing to intensify practical education. Since the integrative concept is based on cooperation of different medical specialties, the students expect one or two physicians to be chiefly responsible for the entire course. Additional dates during the semester interfere with the students' leisure activities and require individual practical activity. This means giving up a passively receptive attitude. However, as reflected by the results of the exams and questionnaires, response to this step of improvement in Emergency Medical Education has been very positive. Future efforts are directed at including more physicians as practical supervisors, scattering of training dates, an increase in compulsory practical participation such as one-day attendance at an intensive care unit, and intensified exams on practical issues. However, the improvement of the quality of teaching is imperative in the job planning of the medical profession.

Clinical Clerkship↗
PubMed1996

Coefficient of variation: a powerful Doppler ultrasonographic parameter for detection of renal artery stenosis.

The aim of our study was to objectively compare the effectiveness of various Doppler parameters in the diagnosis of renal artery stenosis. In three sheep, variable degrees of renal artery stenosis were induced and renal segmental arteries were investigated using pulsed Doppler sonography. In each animal the standard deviation of the instantaneous peak velocity within one cardiac cycle normalized by the mean peak velocity (coefficient of variation) had significantly higher normalized regression coefficients (k* = -0.215, average of three animals) when compared to resistive index (k* = -0.090) and acceleration index (k* = -0.069). In each individual animal, coefficient of variation detected lower pressure gradients (6.3 mm Hg, average value) than did resistive index (13.4 mm Hg) or acceleration index (17.3 mm Hg). The coefficient of variation may detect the presence of pressure gradients in renal artery stenosis more accurately than acceleration index or resistive index.

Animals↗
PubMed1996

[Use of continuous veno-venous high volume hemofiltration (CVVHVH) in patients with multiple organ failure. Principle and applications].

Between 1987 and 1994 in 24 patients suffering from multiple organ failure the new method of continuous high-volume veno-venous hemofiltration (HVCVVH) was performed. Compared with the usual methods of dialysis and hemofiltration the HVCVVH has proven two advantages: at first, it was possible to obtain a high blood flow through the filter powered by a pump. Secondly the fluid withdrawal from the infracardiac body region and the controlled infusion of fluid into the supracardiac veins was possible without decreasing the cardiac preload in patients with severe disorders of volume distribution. 18 of 24 treated patients had a stable circulation without need of catecholamines after the filtration. In 14 of the 24 patients the FiO2 was reduced to 0.3 and decreased during filtration. 13 patients survived the observation time of 30 days, 2 patients died during the procedure of filtration.

Adult↗
PubMed1995

Influence of epidural analgesia on fetal and neonatal well-being.

Epidural analgesia is a frequently used method to reduce the pain of child-bearing. Concerns regarding the safety and potential hazards still persist in the medical community. This review intends to examine how epidural analgesia determines the various factors of fetal and neonatal well-being. Placental drug transfer of opiates like morphine, pethidine and fentanyl is rapid and can lead to neonatal depression. Sufentanil seems to be the safest opiate to administer epidurally. Local anaesthetics are transferred to the fetus in substantial amounts, but the reported effects are subtle and are probably inconsequential. Utero- and fetoplacental blood flow seems to be improved by epidural analgesia with local anaesthetics. Even when using stronger solutions for more extensive blockade in patients for caesarean section, no adverse effects could be demonstrated using pulsed Doppler technique as long as prolonged hypotension (> 2 min) is avoided. Hypotension is best prevented with 20-25 ml/kg crystalloid preload and prompt treatment with ephedrine or etilephrine. Addition of adrenaline to local anaesthetics is considered to be safe for the healthy mother and fetus but it should best be avoided in mothers with pregnancy induced hypertension. Fetal and neonatal acid-base balance and gas-exchange are not adversely affected by epidural analgesia. Many studies show that epidural analgesia can indeed protect the fetus if hypotension is prevented. Neonatal well-being evaluated by APGAR, BRAZELTON, SCANLON and NACS scores is not significantly influenced by local anaesthetics. Neonatal depression can occur however with epidural use of morphine, fentanyl and alfentanil. Sufentanil, again in doses up to 30 micrograms in association with bupivacaine seems to be devoid of depressive effects on the neonate. In summary, the anaesthetist has good arguments to reassure his obstetrical colleagues that providing epidural analgesia for pregnant women in labour is a justifiable intervention to support the natural process of child-bearing.

Analgesia, Epidural↗
PubMed1995

A clinical monitoring system for centrifugal blood pumps.

In clinical application of rotary blood pumps, flow obstruction as a result of suction of the inflow cannula, kinking of tubing, or thrombus formation occurs quite frequently. Early detection of such problems is essential to avoid hemolysis, tissue degradation, or release of thrombi to the patient. A program was developed for automatic observation of pump performance, tubing resistance, and suction effects, which requires only the measurement of already available parameters (i.e., pump speed, pump flow, aortic pressure). The software is based on Visual-C and provides a user surface formatted in Windows. Pump flow, its time derivate, and the relationship between the pulsatile component and the mean graft flow are observed to detect suction in the left atrium. Furthermore, the generated pressure head is predicted from pump speed, graft flow, and the resistance of tubing/cannula and compared with the actually measured aortic pressure. An alarm sounds if a given limit between prediction and measurement is exceeded. In a mock circulation, suction events were detected in more than 95% with a mean deviation of actual aortic pressure from its predicted value of less than 5%. For in vivo application, even incomplete suction could be detected reliably in more than 90% of events. This system improves and standardizes monitoring of pump performance; it should therefore lead to greater safety during application of such devices.

Algorithms↗
PubMed1995

Intrarenal Doppler ultrasonography: which vessel should be investigated?

The aim of our study was to determine whether the site of intrarenal Doppler measurement influences diagnosis of renal artery stenosis. In an experimental test, three sheep with variable degrees of renal artery stenosis were investigated. In each animal, the resistive index from renal segmental arteries correlated better with mean pressure gradient (r = 0.85, 0.71, 0.85) and had lower standard deviation (s = 0.02 to 0.05) than resistive index from interlobar arteries (r = 0.48, 0.54, 0.61) (s = 0.03 to 0.11). In two animals the difference was significant (correlation: P < or = 0.01, P = 0.13, P < or = 0.05; standard deviation: P < or = 0.01, P < or = 0.34, P < or = 0.05). For detecting renal artery stenosis, vessels within the renal sinus should be used for Doppler sampling.

Animals↗
PubMed1995

Extracellular matrix proteins in human bile and gallstones.

OBJECTIVE: To investigate the presence of extracellular matrix (ECM) proteins in human bile and gallstones and to determine whether they play a role in gallstone formation. METHODS: ECM components [procollagen-III-peptide (P-III-P), laminin, and hyaluronic acid] in bile from patients with (n = 22) and without (n = 6) gallstone disease were investigated by immunoassay. Bile, gallstones, and serum were assayed for extracellular matrix components in an additional 19 patients with gallstone disease and gallstones were analysed in a third set of 26 patients. The expression of hyaluronic acid synthetase in bile duct and gall bladder epithelia was investigated by immunocytochemistry. RESULTS: Hyaluronic acid levels were significantly elevated in hepatic and gall bladder bile, but not in the serum of patients with compared with those without gallstone disease (137 versus 81 micrograms/l, respectively; P < 0.05). No differences were found between hepatic and gall bladder bile. Procollagen-III-peptide and laminin were detected in the hepatic bile of patients in both groups. Laminin levels were higher in gall bladder bile than in serum in all patients and measurable amounts of hyaluronic acid were found in gallstones. The amount of hyaluronic acid was inversely correlated to the volume of the gallstone, i.e., the smallest gallstones contained the highest levels of hyaluronic acid. No procollagen-III-peptide or laminin was found in the gallstones. Immunocytochemistry of the epithelial cells of bile duct and gall bladder mucosa stained strongly for hyaluronic acid synthetase. CONCLUSIONS: Hyaluronic acid as a progenitor of ECM can be detected in bile and is significantly elevated in patients with gallstone disease. Small gallstones contain more hyaluronic acid than large stones, suggesting that hyaluronic acid may play a role in gallstone formation, particularly since it is produced by the epithelial lining of bile ducts and is found in gall bladder mucosa.

Adolescent↗
PubMed1994

Identifying relevant studies for systematic reviews.

OBJECTIVE: To examine the sensitivity and precision of Medline searching for randomised clinical trials. DESIGN: Comparison of results of Medline searches to a "gold standard" of known randomised clinical trials in ophthalmology published in 1988; systematic review (meta-analysis) of results of similar, but separate, studies from many fields of medicine. POPULATIONS: Randomised clinical trials published in 1988 in journals indexed in Medline, and those not indexed in Medline and identified by hand search, comprised the gold standard. Gold standards for the other studies combined in the meta-analysis were based on: randomised clinical trials published in any journal, whether indexed in Medline or not; those published in any journal indexed in Medline; or those published in a selected group of journals indexed in Medline. MAIN OUTCOME MEASURE: Sensitivity (proportion of the total number of known randomised clinical trials identified by the search) and precision (proportion of publications retrieved by Medline that were actually randomised clinical trials) were calculated for each study and combined to obtain weighted means. Searches producing the "best" sensitivity were used for sensitivity and precision estimates when multiple searches were performed. RESULTS: The sensitivity of searching for ophthalmology randomised clinical trials published in 1988 was 82%, when the gold standard was for any journal, 87% for any journal indexed in Medline, and 88% for selected journals indexed in Medline. Weighted means for sensitivity across all studies were 51%, 77%, and 63%, respectively. The weighted mean for precision was 8% (median 32.5%). Most searchers seemed not to use freetext subject terms and truncation of those terms. CONCLUSION: Although the indexing terms available for searching Medline for randomised clinical trials have improved, sensitivity still remains unsatisfactory. A mechanism is needed to "'register" known trials, preferably by retrospective tagging of Medline entries, and incorporating trials published before 1966 and in journals not indexed by Medline into the system.

Abstracting and Indexing↗
PubMed1994

[The value of duplex sonography after orthotopic liver transplantation. Experience with 44 patients].

In a prospective study, 44 patients (11 women, 33 men) who had received orthotopic liver transplants underwent a total of 196 consecutive duplex Doppler ultrasound examinations. The aim of the study was to evaluate the correlation between the pulsatile flow index (PFI) and the damping index (DI) as far as complications as rejection or cholangitis were concerned. The patients were examined five times each on average. The PFI and DI were measured in the hepatic artery, the portal vein and the hepatic veins. The findings were compared with the clinical course (cholangitis, rejection) and the histomorphological diagnosis as determined in biopsy specimens. In biopsy-proven rejection episodes, the sensitivity of the PFI in the hepatic artery was 69.4%, the specificity 72.2%. The sensitivity of the DI in the hepatic vein was 89.4%, the specificity 89.1%. Combining the two, specificity was more than 90%. PFI and DI in the portal vein bore no apparent relation to clinical course or histomorphological diagnosis. We found duplex Doppler ultrasound extremely beneficial in determining the timing and indication for liver biopsy. In addition, this simple examination, which can be performed as often as desired, accurately shows the transplanted liver's response to measures taken to counter rejection.

Adult↗
PubMed1994

Comparison of histidine-tryptophan-ketoglutarate (HTK) solution versus University of Wisconsin (UW) solution for organ preservation in human liver transplantation. A prospective, randomized study.

Over a 30-month period, 60 patients (30 in each group) suffering from end-stage liver disease or primary hepatic malignancy and scheduled for liver transplantation were enrolled in a prospective, randomized study to compare two methods of liver preservation: histidine-tryptophan-ketoglutarate (HTK) solution versus University of Wisconsin (UW) solution. Entry criteria for both groups were: age (18-65 years), elective surgery (transplantable or urgent category of the recipients), first transplantations and harvesting procedure performed by the same team. The parameters under investigation were the clinical and laboratory data pre- and post-transplantation, as well as follow-up data such as complications and survival. There were no significant differences in the two groups as far as the evaluation criteria were concerned, even when cold ischemia time was more than 15 h (n = 7). A slight, yet not significant, increase in late complications of the biliary anastomoses could be seen in the UW group. Hepatocellular injury (SGOT, SGPT, GLDH, lactate) appeared to be more marked in the HTK group. These results suggest that both HTK and UW solutions are appropriate for clinical use in liver transplantation, even if cold ischemia time is more than 15 h.

Adenosine↗
PubMed1994

[The effect of substitution with AT III- and PPSB-concentrates in patients with terminal liver insufficiency].

UNLABELLED: Patients with end-stage liver disease frequently develop combined coagulopathies due to increased procoagulant and fibrinolytic turnover as well as thrombocytopenia. The onset of clinical symptoms of a haemorrhagic diathesis requires balanced substitution of coagulation factors, since fresh frozen plasma alone does not always maintain a sufficient haemostatic potential in these patients. This substitution commonly follows standard rules based on the assumption that 0.5-1 IU of a coagulation factor or inhibitor concentrate given per kg body weight will increase its endogenous activity by 1%. We set out to investigate the validity of this standard regime in patients with end-stage liver disease scheduled for orthotopic liver transplantation. PATIENTS AND METHODS: Fifty-one adult patients were prospectively studied. In 37 patients with antithrombin III (AT III) activity < 70%, an AT III preparation (Kybernin, Behring, Marburg, Germany) was given preoperatively (mean dose 2616 +/- 207 IU) following standard calculations in order to increase endogenous activity to 80%. Twenty-seven of the patients had chronic hepatic failure (CHF group) with histologically proven cirrhosis and 10 had acute hepatic failure (AHF group). Blood samples were drawn prior to a 15-min infusion of AT III concentrate and 30 min thereafter. In 14 patients with prothrombin time (PT) < 40%, AT III levels had been corrected earlier during the clinical course to achieve activities > 70%. Prothrombin complex (PPSB, Beriplex, Behring, Marburg, Germany) was substituted (mean dose 2304 +/- 289 IU) to increase procoagulant activity to PT > 60%. Blood samples were drawn in the same fashion as in the AT III group. The amounts of AT III and PPSB concentrates (delta AT III, [IU/kg]; delta PPSB [IU/kg]) required to increase AT III activity and PT, respectively, by 1% were calculated. RESULTS: Standard calculations for AT III substitution indicated AT III recovery in all 37 patients who received AT III concentrate. However, there was a statistically significant difference between patients with CLF and ALF. In patients with CLF, delta AT III was found to be 0.8 IU/kg (+/- 0.1 SEM) and in those with ALF it was 1.5 IU/kg (+/- 0.1 SEM) (P < 0.05, t-test). In patients treated with PPSB concentrate, delta PPSB was 1.6 U/kg (+/- 0.2 SEM) for both CLF and ALF groups. CONCLUSIONS: In patients with end-stage liver disease standard rules for substitution with AT III-concentrate are adequate only for patients with CLF. In patients with ALF higher AT III doses are required to achieve the expected effect on endogenous AT III activity. Procoagulant activity, as reflected by PT, can be increased by 1% when 1.6 IU/kg PPSB concentrate is given. However, this study shows the effects of coagulation concentrates only 30 min after administration. An increased volume of distribution and increased turnover may explain the poor recovery of AT III activity in the ALF group, indicating that the dose of coagulation concentrate should be estimated against the background of the patient's clinical symptoms and diagnosis.

Adult↗
PubMed1994

[Diagnosis and therapy of disseminated intravascular coagulation].

Consumptive coagulation disorders are frequently observed in critically ill patients secondary to other underlying diseases. Initial hypercoagulability leads to subsequent hypocoagulability due to consumption of procoagulant proteins, inhibitors, and platelets. This process evolves in three distinct phases: an initial increase in coagulation activity is characterised by the activation of coagulation factors and platelets without any clinical symptoms of a haemorrhagic diathesis. The ongoing process of activation and accelerated consumption of coagulation factors and inhibitors causes a critical reduction in the haemostatic potential. The time of onset of the clinical symptoms of bleeding depends on the patient's underlying disease and its pharmacological management. Coagulation processes that are restricted locally under normal conditions become disseminated when the inhibitory potential--mainly represented by antithrombin III (AT III)--is exhausted. Therefore, thrombin formation occurs, especially in the microcirculation, where fibrin clot deposition begins to cause inhomogeneities of blood flow and thus to reduce oxygen delivery to the tissues. Hypocoagulability, reactive hyperfibrinolysis, and diffuse bleeding lead to an irreversible systemic breakdown of haemostatic mechanisms (disseminated intravascular coagulation, DIC). The laboratory diagnosis of accelerated consumption is based on the course of global coagulation tests (e.g., prothrombin time, activated partial thromboplastin time, platelet count) and more sensitive ("dynamic") activation parameters such as prothrombin fragment F1 + 2, thrombin-AT III complex, fibrin monomers, or d-dimer. Measurements of plasminogen, tissue plasminogen activator, plasminogen activator inhibitor 1, and alpha 2-antiplasmin-plasmin complex provide information on fibrinolytic turnover.(ABSTRACT TRUNCATED AT 250 WORDS)

Critical Care↗
PubMed1994

A new method of veno-venous bypass during human orthotopic liver transplantation.

Veno-venous bypass is commonly used during orthotopic liver transplantation, but there is some controversy as to whether it contributes to a better outcome. Low shunt flows frequently reduce the efficacy of portofemoro-axillary systems and so a percutaneous cannulation technique for the subclavian and femoral vein with large bore catheters was developed in order to facilitate bypass management. This study reports the performance and complications of a portofemoro-subclavian bypass system during the anhepatic phase of human orthotopic liver transplantation in 85 patients. A percutaneous cannulation technique and two 7 mm (subclavian and femoral) catheters, inserted pre-operatively, were used in a pump driven portofemoro-subclavian bypass system. Coagulation profiles, shunt flows, haemodynamic parameters, and peri-operative complications associated with bypass were recorded for each patient. Percutaneous cannulation of the left femoral and subclavian vein was successful in 78 patients (91.8%). Mean femoro-subclavian shunt flow was 1.45 l.min-1 (SD 0.37), and mean portofemoro-subclavian flow was 4.28 l.min-1 (SD 1.03). Although oxygen delivery was not maintained at pre-shunt levels (559.7 (SD 147) vs 506 (SD 107) ml.min-1.m-2, p < 0.05) renal perfusion pressure stayed above 50 mmHg (during shunt it was 56 (SD 9) mmHg). One intra-operative air embolism was observed (1.2%), and in one patient a myocardial infarction occurred during the anhepatic phase; neither complication was considered to be related to the percutaneous cannulation technique. There were no bleeding complications. After operation, all chest X rays were normal and clinical examination revealed no adverse effects of portofemoro-subclavian bypass.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Effects of hypertonic saline hydroxyethyl starch solution on collagen-induced platelet aggregation and ATP secretion.

OBJECTIVE: The purpose of this study was to investigate the effect of hypertonic (NaCl 7.5%) hydroxyethyl starch (HES 6%, molecular weight 200,000) (HHES) as used for small-volume resuscitation on global coagulation parameters and platelet function. DESIGN: Randomized, controlled clinical trial. SETTING: Intraoperative volume loading after induction of general anesthesia. PATIENTS: 27 consecutive patients [mean age 59 (22-76) years, mean body weight 69.8 (46-98) kg] undergoing abdominal surgery were studied. INTERVENTIONS: Global coagulation tests (aPTT: activated partial thromboplastin time; PT: prothrombin time; platelet count; thrombelastography: TEG), platelet aggregation and ATP release were measured before and 10 min after the application of 4 ml.kg-1 of HHES (study group H, n = 14) or HES (control group C, n = 13). RESULTS: The aPTT was prolonged and platelet count was significantly reduced in both study groups. In contrast to the HES group, clot formation time in the TEG was significantly prolonged and the maximum amplitude was reduced in the HHES group. Furthermore, platelet aggregation was significantly slowed down, whereas ATP release significantly increased in the HHES group. CONCLUSION: The changes in global coagulation parameters can be explained by dilutional effects of the infused solution. The hyperosmolar saline compound of the HHES solution obviously contributes to the slowing down of platelet aggregation. Osmotic stress and membrane pleating may aggravate HES-induced changes in membrane fluidity and microviscosity and thus explain this impaired interaction. The increase in ATP release suggests a change in receptor-second messenger interaction for delta granule release.

Abdomen↗
PubMed1994

[Liver complications of HELLP syndrome--an indication for emergency liver transplantation?].

Three patients were treated suffering from a severe HELLP-syndrome. The problems as far as the diagnostic and therapy are concerned are discussed. All three patients had to be operated on in an emergency state. The operations were performed due to acute and severe abdominal bleeding. Two of the patients needed liver transplantation as an emergency procedure, one of them died after hepatectomy waiting for a graft. Another one died seven weeks after successful transplantation due to prolonged sepsis. The third patient is more than one year after transplantation alive and doing well.

Adult↗
PubMed1994

[Liver complications in HELLP syndrome].

In a 5 years period 5 female patients suffering from a severe HELLP syndrome were treated. The problems concerning diagnostic and treatment are discussed. 3 patients had to be operated on in an emergency state. The operations were performed because of acute and severe abdominal bleeding. Two of the patients needed liver transplantation as an emergency procedure, one of them died after hepatectomy on the list. Another one died 7 weeks after successful transplantation in a state of prolonged sepsis. The two conservatively treated and the one transplanted patient are still alive and well.

Adult↗
PubMed1994

[Normal findings with duplex sonography of liver blood vessels--experience in the examination of 100 patients with healthy livers].

100 patients of our kidney transplantation program and uneventful as regards their liver history were indexed by the pulsatile flow (PFI) of the hepatic artery and the damp curve (DI) of the hepatic veins. The average age of the patients was 36 years (20-50y). The pulsatile flow index (PFI) was calculated as 0.4 to 0.7. The damp index (DI) as 0.3 to 0.54. In 10 of these volunteers the measurement was performed 3 times per day for 5 days: there was no difference to be found in comparison to the values of the total group. The presented values of the PFI and DI give the normal range and will be the basis for further investigations in patients after liver transplantation or suffering from liver diseases.

Adult↗