[Obstacles and facilitators of conducting studies - the perspective of colorectal cancer centers' coordinators]

INTRODUCTION

Clinical trials and health services research are crucial pillars for improving patient care. This paper examines factors inhibiting and promoting the study activity and the knowledge and use of trial registries (e. g. DRKS, StudyBox) as an opportunity to learn about existing studies.

MATERIAL AND METHODS

The coordinators of 274 cancer center sites certified according to the requirements of the German Cancer Society were surveyed using a standardized online questionnaire. Data were analyzed using descriptive and bivariate statistics to identify associations with characteristics of the sites (e. g. patient volume, ownership, teaching status).

RESULTS

176 sites participated in the survey (64.2 %). The central obstacle to study participa-tion from the centers' view is the low number of existing studies. General knowledge of the population about studies was considered low. Trial registries are known to almost all respondents, but are rarely used.

DISCUSSION

The results of the survey suggest that comprehensive measures are needed to sustainably increase the study activity. These include, for example, better information about studies, for example through appropriate databases, and (industry-independent) research funding. One possible way to sensitize patients for studies could be the comprehensive education of the population about the purpose of studies.

Zertifizierte Darmkrebszentren aus Sicht der Zentrumsleitungen: Ergebnisse einer Schlüsselpersonenbefragung

Seit 2003 zertifiziert die Deutsche Krebsgesellschaft (DKG) Organkrebszentren in Deutschland: Nach 8 Jahren Praxis gibt es mehr als 600 zertifizierte Krebszentren, die eine wie im Nationalen Krebsplan geforderte „qualitätsgesicherte onkologische Versorgung“ in Deutschland ermöglichen. Dabei behandeln die mehr als 200 zertifizierten Darmkrebszentren rund 25 % aller Darmkrebsneuerkrankungen. In diesem Artikel wird der Frage nachgegangen, welche Veränderungen das Zertifizierungskonzept in die Zentren gebracht hat.

Neuroendocrine tumours (carcinoids) of the appendix

Neuroendocrine tumours (NETs) of the appendix (formerly 'carcinoids') are rare and are usually detected incidentally after appendectomy. Histopathologically they derive from a subepithelial cell population, which is different from NETs in other sites. They are preferentially located at the tip of the appendix. Tumours <1 cm hardly ever metastasize and are treated by appendectomy. Tumours >2 cm require right hemicolectomy because of a significant risk of metastatic spread. Treatment for lesions 1-2 cm is controversial and needs further characterization of the tumour (i.e. mesoappendiceal invasion, vascular invasion, mitotic activity, proliferation markers) and careful patient risk evaluation. Goblet-cell carcinoids have features resembling both carcinoid and adenocarcinoma and should be treated by hemicolectomy. Overall prognosis of small appendiceal NET is excellent in all ages.

Antibiotic prophylaxis influences cardiovascular stability in complicated surgery

OBJECTIVE

Antibiotic prophylaxis is used in many surgical procedures but there are frequent cardiovascular instabilities following antibiotics in perioperative period. A clinic modelling randomised trial (CMRT) in pigs was developed to compare the effects of 2 commonly used antibiotic combinations on cardiovascular stability during major surgery.

MATERIALS AND METHODS

Thirty pigs (both sexes) were randomised into 3 groups, receiving either saline (placebo), co-amoxiclav or cefuroxime/metronidazole in clinically relevant doses as antibiotic prophylaxis. A laparotomy was performed and the abdomen remained open. Surgical complications were simulated by removing one third of the blood volume. For fluid resuscitation, 500 ml hetastarch (HAES(TM)) were infused rapidly (therapy of complication) and polymyxin B (15 mg/kg bodyweight) was applied for induction of histamine release reactions (complication of therapy). The main end points were histamine release reactions, these were classified by 2 blinded investigators.

RESULTS

Neither cardiovascular changes nor histamine release reactions were detected immediately after the administration of antibiotics or placebo alone. Plasma histamine concentrations increased after bleeding in the co-amoxiclav group (p < 0.05). After fluid resuscitation and induction of anaphylactoid reactions, the median histamine release and cardiovascular changes were not significantly different between the groups. However, the incidence of typical histamine release related reactions differed significantly between the groups: 8/10 for the controls, 6/10 in the co-amoxiclav and 2/10 in the cefuroxime/metronidazole group (p < 0.05).

CONCLUSIONS

The stability and reproducibility of this model clearly demonstrated the concept of a 'clinic modelling randomised trial' as a useful tool. Antibiotic prophylaxis influences the organism's capability to cope with intraoperative bleeding and fluid resuscitation problems. Indeed antibiotic prophylaxis may be beneficial. These effects of antibiotics could only be demonstrated in complex surgical models. Thus new antibiotics should be investigated in complex animal models prior to prospective randomised clinical trials or usage in clinical practice.

Early and late histamine release induced by albumin, hetastarch and polygeline: some unexpected findings

OBJECTIVE

The perioperative use of colloidal plasma substitutes is still under discussion. We therefore conducted a prospective randomised study with three commonly used plasma substitutes to examine their histamine releasing effects in 21 volunteers. MATERIAL OR SUBJETS: 21 male volunteers were enrolled in this prospective, randomised, controlled clinical study. Endpoints were the incidence of early and late histamine release and the time course of the release kinetics. Normovolemic hemodilution technique was used with hydroxyethyl starch (n = 6), human albumin (n = 6) and polygeline (n = 9). Measurement and observation period was 240 min after the start of the plasma substitute infusion. Heart rate, blood pressure, SaO(2), clinical symptoms/signs and plasma histamine were measured during the observation period.

RESULTS

The incidence of histamine release over the whole observation period in all three groups was 100%. Histamine release occurred frequently in all three groups until 30 min (50%-78%) and up to 240 min (late release reaction: 67%-83%) after the start of infusion. Surprisingly even hydroxyethyl starch, which is regarded as a generally safe and effective plasma substitute, caused high incidences of late histamine release (67%). Histamine release is a well known side effect of polygeline and - to a lesser extent - also of albumin, but was a novel finding for hydroxyethyl starch.

CONCLUSIONS

We demonstrated for the first time histamine releasing effects of hydroxyethyl starch over a long period of time after administration. This perioperatively and for intensive care possibly relevant finding should make clinicians aware of late side effects not yet connected with the clinical use of these colloidal plasma substitutes.

Implementing a randomized controlled trial with granulocyte colony-stimulating factor prophylaxis to improve the outcome of high-risk patients with colorectal cancer in the complex clinical setting of multiple surgical interventions

Background

All large multicentre trials with immune modifiers in sepsis faded despite promising preclinical results. Several reasons for this have been discussed in the literature and include patient heterogeneity, different phases of pathophysiological state and trial errors. There are two additional and important points: the interaction of immune modifiers with the complex clinical management was not analysed preclinically and in multicentre trials the surgical management was not standardized.

Methods

Before implementing the clinical trial, the interaction of granulocyte colony-stimulating factor (G-CSF) with various surgical interventions was analysed in clinical modelling randomized trials (CMRTs) in rats, including different antibiotics, heparin, H1 and H2 antagonists, abdominal lavage, and management of preoperative and intraoperative bleeding. Good clinical practice rules were applied and the complexity of clinical reality was modelled in the CMRTs. In the clinical trial, high-risk patients (American Society of Anesthesiologists grades III and IV) with colorectal cancer were identified and randomized to the placebo and G-CSF groups (n = 40 per group). G-CSF prophylaxis (300 μg) was given subcutaneously 12 h before, and 12 and 36 h after operation. The three primary endpoints were health status measured with a modified McPeek index over 6 months, self-reported quality of life determined with the European Organization for the Research and Treatment of Cancer QLQ38 questionnaire and the true endpoint defined 6 months after operation.

Results

Implementation of the trial demonstrated that a high standardization of surgical management is not possible in multicentre trials since the surgical management of patients with colorectal cancer is heterogeneous and management of the most important complication, anastomotic leakage after colorectal surgery, is performed according to personal experience and is not based on high levels of evidence from clinical trials low evidence based medicine (EBM). For this reason the surgical management of patients in the trial should be defined, a centre-based clinical guideline for the management of anastomotic leakage applied and adherence to the guideline recorded.

Conclusion

Without CMRTs to analyse the interaction of immune modifiers in complex settings and defined clinical management of patients, no positive results will be obtained from such clinical trials.

Granulocyte colony-stimulating factor but not peritoneal lavage increases survival rate after experimental abdominal contamination and infection

BACKGROUND

The value of peritoneal lavage for intra-abdominal contamination and infection has never been proven scientifically. In contrast, the stimulation of host defence mechanisms with cytokines such as granulocyte colony-stimulating factor (G-CSF) has appeared promising in recent clinical trials.

METHODS

Clinic modelling randomized trials (CMRTs), which model the complexity of the clinical reality, were used in rats in which peritoneal contamination and infection (PCI) was produced with human stool bacteria. The following groups were compared: trial 1, intraoperative peritoneal lavage with saline versus taurolin (18 rats per group); trial 2, no lavage versus saline lavage versus saline lavage plus subcutaneous administration of G-CSF (18 rats per group); trial 3, lavage with saline versus no lavage (30 rats per group). The primary endpoint was mortality at 120 h. Secondary endpoints were the phagocytic activity of granulocytes, and systemic and peritoneal cytokine levels.

RESULTS

In trial 1 lavage with taurolin was not superior to that with saline (five of 18 versus eight of 18 animals survived; P = 0.32). In trial 2, six of 18 animals having no lavage and three of 18 receiving saline lavage survived. The combination of lavage and G-CSF increased the number of animals surviving to 11 of 18 (P < 0.05). Lavage combined with G-CSF stimulated granulocyte phagocytic activity (P < 0.01) and reduced the levels of interleukin (IL) 6 (P < 0.01) and tumour necrosis factor alpha (P < 0.05) in peritoneal fluid, as well as plasma levels of IL-6 (P < 0.05) and IL-10 (P < 0.01). In trial 3, survival was not significantly different in animals having lavage (14 of 30) and no lavage (19 of 30) (P = 0.14).

CONCLUSION

In these CMRTs of intra-abdominal contamination and infection, peritoneal lavage was not beneficial, but when lavage was combined with subcutaneous administration of G-CSF mortality was reduced and the local and systemic cytokine response was downgraded. Results from these CMRTs were used directly to define the trial conditions of a randomized clinical trial with G-CSF. Peritoneal lavage is not recommended.

Quality of life profile: from measurement to clinical application

Quality of life (QoL) can be assessed in an accurate, valid and reliable way by means of standardized QoL questionnaires and is an important endpoint in clinical trials today. The aim of this study is to implement quality of life as a diagnostic tool for problem-oriented follow-up care of cancer patients. This is done in the framework of an intervention study in the area of regional health care research using qualitative analysis and the methodological concept of barrier analysis. We developed the diagnostic tool by generating individual, graphic QoL profiles based on patients' responses to the EORTC QLQ-C30 and the corresponding disease-specific modules BR23 for breast cancer and CR38 for rectal cancer. The clinical application is investigated by assessing physicians' responses. The QoL profile is judged as a useful diagnostic tool by all participating physicians. It enables physicians to assess the QoL of the patient and incorporate the knowledge they gain in their daily practice. Especially in breast cancer follow-up care QoL profiles give added value to both patients and doctors. The next implementation steps have to extend the concept of QoL to larger groups of patients and physicians by overcoming the restraining factors as identified in the barrier analysis.

[Surgical therapy of rectal carcinoma. Portrayal of the current health care status within the scope of a district quality assurance study]

In an era of economic pressure, patient's participation in decision-making and evidence-based medicine, the need for quality assurance of medical processes in daily routine becomes increasingly important. The aim of this quality assessment study is to demonstrate the real state of surgical care of patients with rectal carcinoma in the context of a field study on quality management in oncology.

METHODS

Prolective cohort-study, small-area-analysis. Between 01.01.1997 and 31.12.1998, all patients with newly diagnosed rectal carcinoma and treatment in the county of Marburg-Biedenkopf (252.975 inhabitants, 3 hospitals) were included in the study. Documentation included all variables (n = 82) relevant for primary surgical therapy according to guidelines and standards.

RESULTS

146 consecutive patients fulfilled the inclusion criteria. 93% underwent resection of the tumor. In 6.6% of these cases rigid rectoscopy for determination of the tumor's distance from the anal verge was not performed. In 16.9% the colon was not examined completely. In 98.5% the state of distant metastases was documented preoperatively. 93% of the patients with tumors in the upper/middle third of the rectum and curative-intent surgery (n = 68) received a sphincter-saving operation. For all curative-intent procedures negative resection margins were confirmed histologically. Complication rates were 31.6% for anterior resection and 46.9% for abdominoperineal extirpation.

CONCLUSIONS

Comparative analysis of quality indicators revealed a predominantly good quality of care. Improving efforts can now be concentrated on few areas of suboptimal quality in the setting of internal quality management. Critical results require detailed analysis of the single cases. Thus, conditions requiring deviation from guidelines become apparent.

Nasogastric tube versus gastrostomy tube for gastric decompression in abdominal surgery: a prospective, randomized trial comparing patients' tube-related inconvenience

BACKGROUND

Perioperative decompression of the stomach is still a common procedure and can be achieved using either nasogastric tubes (NTs) or gastrostomy tubes (GTs). While both procedures appear to be equally effective, some authors believe that NTs are less convenient for patients than GTs. However, to date, no reliable prospective data are available on this issue.

METHODS

We conducted a prospective, randomized trial comparing NTs versus GTs with a total of 110 patients undergoing elective colon surgery. The primary outcome measure was the patient's tube-related inconvenience and pain, assessed in a standardized interview on day 2 after surgery and quantified by means of a visual-analog scale (VAS). A questionnaire including the EORTC QLQ-C30 and additional items regarding retrospective tube-related judgements was administered on the day of discharge and 4 weeks after discharge. Secondary endpoints were the therapy-related morbidity and general complications.

RESULTS

When patients were asked which of their drainage tubes (all patients had three or four drainage tubes, such as decompression drains, urinary drains, central venous line) was most inconvenient, 43% (CI 33-53%) in the NT group reported that the NT was most inconvenient, while only 4% (CI 1-10%) of the GT patients judged the GT most inconvenient ( P<0.001, Chi(2) test). This effect was also found in VAS ratings of inconvenience and discomfort ( P<0.01). Also postoperatively (p.o.), NT patients evidenced less preference for their tube system (day 2 p.o.: 71%, CI 61-80%; 4 weeks p.o.: 66%, CI 56-75%) than did GT patients (day 2 p.o.: 94%, CI 88-98%; 4 weeks p.o.: 91% CI 84-96%); again, these differences were statistically significant ( P<0.02; Chi(2) test). No differences between groups emerged regarding global quality of life or conventional clinical outcomes.

CONCLUSION

This prospective randomized trial supports the clinical observation that NT causes more subjective inconvenience than GT. In cases when a prolonged postoperative ileus is expected, decisions for a prophylactic decompressing tube system have to weigh up the possibilities of different averse clinical as well as subjective outcomes. It is then preferable to include patients' preferences in the individual decision making process (shared-decision making).

Granulocyte-colony stimulating factor in the prevention of postoperative infectious complications and sub-optimal recovery from operation in patients with colorectal cancer and increased preoperative risk (ASA 3 and 4). Protocol of a controlled clinical trial developed by consensus of an international study group. Part three: individual patient, complication algorithm and quality manage

GENERAL DESIGN

Presentation of a new type of a study protocol for evaluation of the effectiveness of an immune modifier (rhG-CSF, filgrastim): prevention of postoperative infectious complications and of sub-optimal recovery from operation in patients with colorectal cancer and increased preoperative risk (ASA 3 and 4). A randomised, placebo controlled, double-blinded, single-centre study is performed at an University Hospital (n = 40 patients for each group). This part presents the course of the individual patient and a complication algorithm for the management of anastomotic leakage and quality management.

OBJECTIVE

In part three of the protocol, the three major sections include: The course of the individual patient using a comprehensive graphic display, including the perioperative period, hospital stay and post discharge outcome. A center based clinical practice guideline for the management of the most important postoperative complication--anastomotic leakage--including evidence based support for each step of the algorithm. Data management, ethics and organisational structure.

CONCLUSIONS

Future studies with immune modifiers will also fail if not better structured (reduction of variance) to achieve uniform patient management in a complex clinical scenario. This new type of a single-centre trial aims to reduce the gap between animal experiments and clinical trials or--if it fails--at least demonstrates new ways for explaining the failures.

Granulocyte-colony stimulating factor in the prevention of postoperative infectious complications and sub-optimal recovery from operation in patients with colorectal cancer and increased preoperative risk (ASA 3 and 4). Protocol for a controlled clinical trial developed by consensus of an international study group. Part two: design of the study

GENERAL DESIGN

Presentation of a new type of a study protocol for evaluation of the effectiveness of an immune modifier (rhG-CSF, filgrastim): prevention of postoperative infectious complications and of sub-optimal recovery from operation in patients with colorectal cancer and increased preoperative risk (ASA 3 and 4). This part describes the design of the randomised, placebo controlled, double-blinded, single-centre study performed at an university hospital (n = 40 patients for each group).

OBJECTIVE

The trial design includes the following elements for a prototype protocol: * The study population is restricted to patients with colorectal cancer, including a left sided resection and an increased perioperative risk (ASA 3 and 4). * Patients are allocated by random to the control or treatment group. * The double blinding strategy of the trial is assessed by psychometric indices. * An endpoint construct with quality of life (EORTC QLQ-C30) and a recovery index (modified Mc Peek index) are used as primary endpoints. Qualitative analysis of clinical relevance of the endpoints is performed by both patients and doctors. * Statistical analysis uses an area under the curve (AUC) model for improvement of quality of life on leaving hospital and two and six months after operation. A confirmatory statistical model with quality of life as the first primary endpoint in the hierarchic test procedure is used. Expectations of patients and surgeons and the negative affect are analysed by social psychological scales.

CONCLUSION

This study design differs from other trials on preoperative prophylaxis and postoperative recovery, and has been developed to try a new concept and avoid previous failures.

Granulocyte-colony stimulating factor in the prevention of postoperative infectious complications and sub-optimal recovery from operation in patients with colorectal cancer and increased preoperative risk (ASA 3 and 4). Protocol of a controlled clinical trial developed by consensus of an international study group. Part one: rationale and hypothesis

GENERAL DESIGN

Presentation of a novel study protocol to evalue the effectiveness of an immune modifier (rhG-CSF, filgrastim): prevention of postoperative infectious complications and sub-optimal recovery from operation in patients with colorectal cancer and increased preoperative risk (ASA 3 and 4). The rationale and hypothesis are presented in this part of the protocol of the randomised, placebo controlled, double-blinded, single-centre study performed at an university hospital (n = 40 patients for each group).

OBJECTIVE

Part one of this protocol describes the concepts of three major sections of the study: Definition of optimum and sub-optimal recovery after operation. Recovery, as an outcome, is not a simple univariate endpoint, but a complex construction of mechanistic variables (i. e. death, complications and health status assessed by the surgeon), quality of life expressed by the patient, and finally a weighted outcome judgement by both the patient and the surgeon (true endpoint). Its conventional early assessment within 14-28 days is artificial: longer periods (such as 6 months) are needed for the patient to state: "I am now as well as I was before". Identification of suitable target patients: the use of biological response modifiers (immune modulators) in addition to traditional prophylaxes (i. e. antibiotics, heparin, volume substitutes) may improve postoperative outcome in appropriate selected patients with reduced host defence and increased immunological stress response, but these have to be defined. Patients classified as ASA 3 and 4 (American Society for Anaesthesiologists) and with colorectal cancer will be studied to prove this hypothesis. Choice of biological response modifier: Filgrastim has been chosen as an example of a biological response modifier because it was effective in a new study type, clinic-modelling randomised trials in rodents, and has shown promise in some clinical trials for indications other than preoperative prophylaxis. It has also enhanced host defence and has been anti-inflammatory in basic research.

CONCLUSION

The following hypothesis will be tested in patients with operations for colorectal cancer and increased preoperative risk (ASA 3 and 4): is the outcome as evaluated by the hermeneutic endpoint (quality of life expressed by the patient) and mechanistic endpoints (mortality rate, complication rate, relative hospital stay, assessed by the doctor) improved in the group receiving filgrastim prophylaxis in comparison with the placebo group? Quality of life will be the first primary endpoint in the hierarchical, statistical testing of confirmatory analysis.

Expression and NNK reducing activities of carbonyl reductase and 11beta-hydroxysteroid dehydrogenase type 1 in human lung

The tobacco specific nitrosamine 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK), which is found in high amounts in tobacco products, is believed to play an important role in lung cancer induction in smokers. NNK requires metabolic activation by cytochrome P450 mediated alpha-hydroxylation to exhibit its carcinogenic properties. On the other hand, NNK is inactivated by carbonyl reduction to its alcohol-equivalent 4-methylnitrosamino-1-(3-pyridyl)-1-butanol (NNAL) followed by glucuronidation and final excretion into urine or bile. Carbonyl reduction and alpha-hydroxylation are the predominant pathways in man, and it has been postulated that the extent of these competing pathways determines the individual susceptibility to lung cancer. Moreover, only a minor part of all habitual smokers develop lung cancer, suggesting the existence of susceptibility genes. Microsomal 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD 1) (EC 1.1.1.146) and cytosolic carbonyl reductase (CR) (EC 1.1.1.184) have been shown to be mainly responsible for NNAL formation in liver and lung. In the present study, we performed comparative investigations of human lung tissue samples from several patients with respect to the expression and activity of 11beta-HSD 1 and carbonyl reductase. We observed varying levels in 11beta-HSD 1 and carbonyl reductase expression in these patients, as revealed by RT-PCR and ELISA. Also, the tissue samples showed a different activity and inhibitor profile for both enzymes. According to our results, variations in the expression and activity of NNK carbonyl reducing enzymes may constitute a major determinant in the overall NNK detoxification capacity and thus may be linked to the great differences observed in the individual susceptibility of tobacco-smoke related lung cancer.

Parathyroid xenotransplantation without immunosuppression in experimental hypoparathyroidism: long-term in vivo function following microencapsulation with a clinically suitable alginate

Permanent hypoparathyroidism is one of the most difficult of all endocrine disorders to treat medically. Because this deficiency syndrome rarely is a life-threatening condition, systemic immunosuppression for recipients of transgenic transplants is not justified. An alternative would be protecting the tissue to be transplanted from the immunologic response (immunoisolation) by coating it with a semipermeable membrane- microencapsulation. Unfortunately, prior to the first clinical use, further analysis of the coating substance (alginate) demonstrated that it has potential cancerogenic properties. Using a purified amitogenic alginate suitable for clinical use, we accomplished allotransplantation in a long-term animal model and reported the first clinical cases without postoperative immunosuppression recently. In view of the potential clinical use, we investigated the ability of the microencapsulation technology with the novel amitogenic alginate in experimental hypoparathyroidism (80 parathyroidectomized rats) to enable transgenic transplantation across the highest immunologic barrier (xenotransplantation: human to rat) to ensure intact transplant function without immunosuppression. In a controlled, long-term animal study, the effect of microencapsulation on xenotransplanted human parathyroid tissue was evaluated over a period of 30 weeks (microencapsulated and naked hyperplastic parathyroid tissue, respectively). Functionally, human parathyroid tissue was able to replace that of rats. More than 6 months after xenotransplantation 32 of 40 animals that had received microencapsulated transplants were normocalcemic. In contrast, serum calcium concentrations dropped to postparathyroidectomy levels within 3 weeks in the animals that had received naked tissue only. Correspondingly, normocalcemic animals showed vital parathyroid tissue inside the microcapsules, which were surrounded by a small rim of fibroblasts. When combining microencapsulation with an improved tissue culture method, xenotransplantation of human parathyroid tissue and maintenance of its physiologic function is reproducibly achieved over the highest transplantation barrier. Using the amitogenic alginate may be a crucial step toward the first clinical use of this technique for parathyroid xenotransplantation without immunosuppression.

Are covered stents really effective at closing esophagotracheal fistulas? Results of an animal study

PURPOSE

To determine whether covered self-expanding metal stents successfully exclude experimentally created esophagotracheal fistulas.

METHODS

Esophagotracheal fistulas were surgically created in the upper third of the esophagus in 12 minipigs and immediately sealed by implantation of a covered self-expanding metal stent (20 mm expanded diameter) in the esophagus. Before the animals were killed, after 3, 7, 14, 28, 30, and 36 days, the position of the stent and the sealing of the fistula were monitored fluoroscopically. The esophagus, trachea, and both lungs were examined histologically.

RESULTS

Creation of an esophagotracheal fistula was successful in all cases. All fistulas were widely patent at autopsy. The technical success rate for stent deployment and initial sealing of the fistula was 100%. During follow-up, five stents migrated distally, but none into the stomach. Therefore, the fistula was no longer excluded in five animals. In seven animals the stent sealed the fistula until the death of the animal. Tracheal narrowing necessitated additional tracheal stenting in three animals. Two minipigs died due to aspiration of food. Histologic examination showed signs of aspiration in all animals with stents in place for longer than 2 weeks.

CONCLUSION

This experimental animal study revealed worse results for sealing of esophagotracheal fistulas with covered self-expanding metal stents than have been reported for the clinical use of these devices.

Platelet aggregation during abdominal surgery in an experimental pig model: the effects of presurgical antibiotic protocols and volume replacement with hydroxyethyl starch

The effect of presurgical antibiotic protocols in combination with hemodilution on platelet aggregation was studied. Thirty pigs were randomly assigned to three groups. Group 1 received amoxicillin/clavulanic acid, group 2 metronidazole+cefuroxime, and group 3, as a control, sodium chloride. They underwent laparotomy, massive blood loss, and volume replacement with hydroxyethyl starch 200, followed by an anaphylactoid reaction. Platelet aggregation was measured by the turbidometric method. Neither antibiotic protocols had any effect on platelet aggregation as compared with the control group. In all three groups, aggregation to ADP and collagen was significantly reduced after volume replacement with hydroxyethyl starch. In contrast, the sensitivity to the aggregating effects of collagen was increased as assessed by a higher frequency of responses to low concentrations of collagen and a shortened latency of the aggregation response after collagen addition. Further in vitro studies revealed that dilution of plasma with hydroxyethyl starch specifically induced the changes seen after in vivo volume replacement. The results suggest that the plasma substitute hydroxyethyl starch 200 increases the sensitivity to low doses of collagen, an effect never described before and considered of clinical relevance.

Carbonyl reduction of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) by cytosolic enzymes in human liver and lung

The tobacco specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a potent pulmonary carcinogen, independent of the route and type of administration. There are competing metabolic activation and detoxification pathways. NNK is activated by alpha-hydroxylation at either the methyl or methylene carbonyl adjacent to the N-nitroso group to yield intermediates that methylate and pyridyloxobutylate DNA. Detoxification of NNK in humans usually occurs via carbonyl reduction to its hydroxy product NNAL, which undergoes glucuronosylation and final excretion. In vitro studies on NNK metabolism have usually been performed with tissue homogenates, microsomal fractions and/or purified microsomal enzymes, but cytosolic metabolism of NNK has been ignored until today. The results of this study demonstrate that cytosolic fractions of human liver and lung also participate in NNK metabolism. We provide evidence that a substantial degree of NNK carbonyl reduction occurs by cytosolic enzymes and that these enzymes may contribute to NNK detoxification in human liver and lung. The relative contribution of cytosolic vs. microsomal NNK carbonyl reduction is nearly identical in liver, whereas it is more than 3-fold higher in lung microsomes compared to lung cytosol. The inhibition profile suggested that mainly carbonyl reductase (EC 1.1.1.184) was active in cytosol of both organs. The expression of carbonyl reductase mRNA in liver and lung was proven by reverse transcription-(RT)-PCR. In conclusion, the results of this study provide the first data on cytosolic enzymes participating in NNK detoxification in human liver and lung.

[Clinical guidelines as part of total quality management. Analysis of heterogenous treatment concepts of sepsis in various clinics with computer assisted generation, logical testing and complexity assessment of clinical algorithms]

Generation, local tailoring, implementation and evaluation of clinical guidelines is an integral part of quality management. Clinical guidelines are intimately related to the independency of physicians' decisions. By this the physicians should be responsible for guideline development and guarantee the use of adequate methods of total quality management and outcome assessment. Formal consensus finding and transparency of evidence are necessary to guarantee the use of guidelines. Clinical algorithms are highly formalized and they are well suited for generation and analysis by the software ALGO. Determination of complexity and comparison of the clinical contents of algorithms is done by the scores CASA (Clinical Algorithm Structural Analysis) and CAPA (Clinical Algorithm Patient Abstraction). In a study of 22 clinical departments on treatment management concepts in sepsis following anastomotic insufFiciency in colorectal carcinoma a considerable heterogeneity was shown using this program.

[The problem of interactions in perioperative prophylaxis: reducing the risk or increasing the risk?]

Risk research and risk analysis have to be modeled as a fairly complex system including multivariate regression modeling for risk factors in etiology, Markov models in pathogenesis, and a construct of mechanistic and hermeneutic variables for clinical outcome analysis. The McPeek index is proposed as an example. Several prophylaxes for risk reduction in the perioperative period produce risk reduction as well as risk augmentation in different types of outcome. These unexpected findings were observed not only in clinical trials, but also in animal experiments and in isolated tissues. This demonstrates a basic problem of handling complexity in the real clinical setting.

[Expenditure and reliability of ICD/ICPM-coding in routine surgery]

Because of the changing legal basis for hospital reimbursement German hospitals have to classify their cases by ICD-9- and an adapted ICPM code (OPS-301) and have to give an advance calculation of the Diagnosis Related Groups (DRG) starting from January 1996. From January 1st 1996 to the 31st of December 1996 all diagnoses and therapies in a general surgery hospital were classified according to ICD-9- and ICPM (OPS-301). This coding was not computer-assisted but was controlled in a multiple step process. As a consequence 4.6% incorrect codes were found which were irrelevant for reimbursement. 7.2% misclassifications relevant for funding were detected with an obvious learning curve within the first 6 months. The calculation of the distribution of diagnoses and therapies reveals that 80 to 85% of the total spectrum in a general surgery hospital (including vascular and thoracic surgery) were covered by 200 diagnostic and therapeutic codes, respectively. This investigation confirms the need for a physician-based control system of diagnostic and therapeutic coding to minimise economic risks.

Localization of the peritoneal reflection in the pelvis by endorectal ultrasound

BACKGROUND

Large adenomas and low-risk rectal carcinomas (T1) that are localized distal of the pelvic peritoneal reflection (PPR) are treated by transanal excision. However, the location of the PPR varies widely and cannot be detected reliably by preoperative methods. Therefore, we evaluated the value of endorectal ultrasound (EUS) for the prediction of an intraperitoneal location of rectal tumors.

METHODS

Fourteen patients with rectal tumors measuring </=15 cm from the anal verge were examined by EUS. If peristalsis beyond the rectal wall or any intraperitoneal fluid was seen at the proximal tumor edge, the lesion was classified as localized above or in the level of the PPR. During the operation, the surgeon determined whether the upper end of the tumor reached the PPR.

RESULTS

In each of our 14 patients, the prediction by EUS was correct. In two patients, a small rectal tumor was excised with an electric sling during rectoscopy, but the polyp bases were not free of dysplastic epithelial tissue. The point where these two polyps were removed could be visualized by endoscopy but not by EUS. Once the relevant area was marked with a titanic endoclip, EUS was able to predict the resection place in relation to the PPR in these two patients as well.

CONCLUSIONS

Although this knowledge would be very important for the therapeutic strategy of small rectal tumors, it is impossible to determine the location of a rectal tumor with regard to the PPR either clinically or by endoscopy. EUS provides this information with high reliability. Thus, we recommend EUS as the method of choice for predicting the location of the PPR.

[Reduction of cardiovascular disorders by preventive perioperative antihistamine administration in general surgery: are the drugs interchangeable?]

In clinical reality the drugs used for H1/H2-prophylaxis are not restricted to the combination of dimetinden/cimetidine, also only for this combination the effectiveness for preventing severe cardiorespiratory disturbances is proven in a randomised controlled clinical trial. However, it is almost impossible to conduct such an extended clinical trial in order to check all possible combinations. Instead of this, we developed a complex animal model featuring clinical variability and the principles of a well conducted randomised controlled clinical trial (CMRT = clinic modelling randomised trials), to evaluate different H1/H2 combinations. In this CMRT in pigs (four groups of 15 animals), the H1/H2 combination of dimetinden/cimetidine and dimetinden/famotidine showed an effectiveness similar to the randomised clinical trial. With dimetinden/ranitidine no significant prophylactic effect was observed. Two conclusions can be drawn: (1) CMRTs in animals are able to answer relevant clinical and research questions that otherwise only could be solved by clinical studies and may be a successful intermediate between basic research and clinical trials. (2) Drugs, even of the same substance class, may not be simply exchangeable. Hence, before changing a proven medication, trials in an adequate complex animal model (CMRT) should be mandatory.

[Heterologous transplantation of human parathyroid glands after microencapsulation with clinically suitable alginate : long-term function without immunosuppression in the animal model]

The role of parathyroid transplantation for the therapy of permanent hypoparathyroidism is undisputed. Because the parathyroid hormone deficiency syndromee rarely every is a vital thread to patients affected, systemic immunosuppression for transplant recipients is not justified. A technique of microencapsulation was modified for transplantation of parathyroid tissue. Using a core substance suitable for clinical use (amitogenic alginate), we accomplished allotransplantation of functioning parathyroid tissue in the long-term animal model and, very recently, reported first clinical cases without postoperative immunosuppression. In a controlled animal model of totally parathyroidectomized rats (PTX, two groups of n = 40), we investigated the ability of microencapsulation with the amitogenic alginate to enable transplantation across the highest immunological barrier (xenotransplantation: human-rat); to ensure intact transplant function and to protect from rejection. Rat parathyroid hormone (PTHRA i.S.) and serum calcium levels served as parameters of completeness of PTX; intact human PTH (PTHRA i.S.) and serum calcium levels of recipient animals were used to assess graft function. Also, tissue integrity within explanted capsules was assessed by histology. Cultured and microencapsulated parathyroid tissue resumes and maintains function in vivo, even if transplanted across the highest immunological barrier. Functionally, PTHHU i.S. replaced (PTHRA i.S.) in PTX animals entirely and restored normocalcemia. These results suggest, that xeno-transplantation of the parathyroids can be achieved without postoperative immuno-suppression in a long term animal model. These data also imply the possibility of clinical heterotransplantation of parathyroid glands.

[Effect of perioperative antibiotic prophylaxis on hemodynamic stability during surgery: detection of complex interaction in a simulated clinical randomized animal study]

In a clinic modelling randomised trial (CMRT) in three groups of 10 land-race pietren pigs each it could be shown that the influence of prophylactic antibiotic administration on intraoperative hemodynamic stability and histamine release is only evident, if by stepwise addition of complicating factors the overall complexity of the experimental setting is increased. Different antibiotic regimen for prophylaxis significantly affected the incidence of cardiovascular instabilities only after relevant blood loss, restoration of circulation and subsequent submaximal induction of anaphylactoid reactions by the histamine liberator Polymyxin B. In conclusion, preclinical testing of therapeutic agents in complex clinic modelling randomised trials should be mandatory to avoid the possible hazards of misconducted clinical trials.

[The longitudinal muscle of the anal canal]

The longitudinal muscle (LM) represents a strong muscular structure of the anal canal situated between the internal (IAS) and the external anal sphincter (EAS). Terminal fibres of this muscle insert at the submucosa of the anal canal, representing the m. canalis ani. Others cross the subcutaneous part of the EAS to become the m. corrugator ani. Thus, the LM connects the visceral and somatic parts of the anal sphincter complex. Histologically ganglionic cells and as Vater-Pacinian corpuscles can be identified inside the LM. Morphology, topography and histology of the LM suggest that this muscle participates in maintaining anorectal continence. It is mandatory that the exact functions of this muscular structure be to elaborated upon, if we are to understand the mechanism of anorectal continence.

The anatomical basis of anal endosonography. A study in postmortem specimens

PURPOSE

Anal endosonography is an imaging modality new to the diagnostic workup of incontinence. Interpretations even of normal endosonomorphologic findings now vary considerably. The conjoined longitudinal muscle (LM), a widely ignored structure, has until recently not been fully recognized by anal endosonography. The aim of this study, therefore, was to accurately determine the normal anatomy of the anal canal and correlate it with the findings obtained by anal endosonography.

METHODS

Eight postmortem specimens of the anal canal were examined by endosonography. The findings were correlated with macroscopical dissection and gross sectional histology of the same specimens.

RESULTS

The external echogenic ring is composed of two anatomical structures: the LM and the external anal sphincter (EAS). However, during anal endosonography the LM cannot always be differentiated from the EAS. Histologically, the relation of the diameters of the LM and the EAS ranged from 0.45:1 to 1.25:1. The narrow hyperechogenic ring between the inner hypoechoic layer and the external hyperechoic ring is an artificial finding that cannot be related to a distinct anatomical structure and most likely represents a sonographic interface.

CONCLUSIONS

This study exactly outlines the relation of diameters of the conjoined longitudinal muscle and external anal sphincter for the first time. Until now, the LM has been underestimated in its dimensions. The role of such a thick muscular structure should be included in the conception of anal continence in the future. Especially in view of the fact that anal endosonography is increasingly used in the diagnostic workup of incontinence and fistula in ano, it is essential to understand the anatomical basis of endosonography. This study accurately delineates the sonomorphology of the anal muscles. When viewed in light findings reported here, endosonographic findings in diseases of the anal canal are nor based on a correct idea of the correlation between endosonomorphology and anal anatomy.

[Aspiration-induced lung complications following emergency endoscopy in upper gastrointestinal hemorrhage: incidence and localization by thoracic radiography]

PURPOSE

Determination of incidence and mortality of pulmonary pathologies arising after gastroscopy for acute bleeding, of left to right ratio of pulmonary findings in postgastroscopic chest films, and determination of a possible relationship between bleeding activity and frequency of aspiration.

METHODS

174 patients with emergency gastroscopies for upper gastrointestinal haemorrhage with pre-/postendoscopy chest films, retrospective analysis. Of the pulmonary findings, infiltrates and atelectases were considered.

RESULTS

After emergency gastroscopy, 16% of patients had infiltrates or atelectases at chest radiography. Mortality within 30 days in the study group was 18%, and 39% among the subgroup with radiologically proven pulmonary complications. The distribution of chest findings between left and right side was 1:1,3. In the subgroup with gastroscopic signs of bleeding the share of postgastroscopic pulmonary findings was slightly superior to that of patients without direct signs of bleeding; however, the difference was statistically not significant.

CONCLUSION

Endoscopy-related aspirations do not seem to account for an increased rate of pulmonary complications after emergency gastroscopy.

Histamine release in sepsis: a prospective, controlled, clinical study

OBJECTIVE

To determine if histamine release occurs in clinical sepsis.

DESIGN

Prospective, controlled, clinical study.

SETTING

Interdisciplinary intensive care unit and trauma ward.

PATIENTS

Sepsis was confirmed in 20 patients (test group) by the criteria of the Veterans Administration Systemic Sepsis Cooperative Study Group (1987) and was verified by positive blood culture. In addition, patients were scored by the Elebute and Stoner Sepsis Score (1983), as modified by Dionigi et al (1985). A concomitant control group consisted of 20 postoperative patients with non-life-threatening trauma to the extremities and without signs of local or systemic infection.

INTERVENTIONS

Observational study. Blood samples were collected for determination of plasma histamine concentrations in both groups at the time of study entry and on five succeeding days.

MEASUREMENTS AND MAIN RESULTS

The patients were well matched, and the groups were not significantly different for all criteria known to influence histamine release. Comparison of the median values of each group on days 1 through 5 demonstrated significantly higher plasma histamine values in the test group on days 1 through 4, but these values were no longer significantly higher on day 5. While none of the nonseptic control patients achieved a plasma histamine concentration of > 1 ng/mL (the concentration of which was considered to be the pathologic cutoff point representing histamine release), these values (i.e., > 1 ng/ mL) were found in nine of 20 test group patients. In the test group, nonsurvivors (n = 9) had significantly higher plasma histamine concentrations than survivors (n = 11) throughout the whole study and eight of nine nonsurvivors showed a plasma histamine concentration of > 1 ng/mL. Correlation of plasma histamine concentrations on day 1 to sepsis severity (initial Sepsis Score) showed that all but one patient with a combined low Sepsis Score (< 20 points) and histamine concentration of < 1 ng/mL survived, while all patients with a Sepsis Score of > 20 points and histamine release (plasma histamine concentration of > 1 ng/mL) died.

CONCLUSION

Increased histamine concentrations were shown to be causally associated (contributory determinant) with sepsis.

Surgical management for carcinoid tumors of small bowel, appendix, colon, and rectum

Carcinoid tumors occur most frequently in the gastrointestinal tract. Despite their ability to produce hormones, most of the midgut and hindgut carcinoids covered in this study are clinically silent, and the diagnosis is often not made before emergency surgery or evaluation for liver metastases. Because the rate of lymph node involvement and the prognosis of carcinoid tumors depend on their site and size, surgery refers to these two factors too. Lymph node metastases are most commonly found with small bowel carcinoids (20-45%), providing the rationale for an extended resection including the adjacent lymph node drainage area. Carcinoid tumors of the appendix < 1 cm in diameter rarely metastasize, simply requiring appendectomy for treatment. Lesions > 2 cm should be treated by right hemicolectomy because of their approximately 30% risk of lymph node metastases. Resection should always be done for carcinoid tumors of the colon resection as for adenocarcinomas. Rectal carcinoids < 2 cm rarely metastasize, directing the conclusion that for these smaller lesions local excision is sufficient; for lesions >2 cm a standard cancer resection should be performed provided distant metastases are absent. In general, the younger the patient or the larger the primary tumor, the more aggressive the treatment should be.

[Interventional endoscopy with the argon plasma coagulator: experiences in general surgery]

The results of the application of argon plasma coagulation (APC) in surgical endoscopy on tumorous stenosis of the esophagus and trachea, angiodysplasia and gastrointestinal bleeding are presented here. Primary therapeutic goals were always achieved and complications were harmless except one loss after duodenal perforation. We conclude that APC is a useful and easily handled tool in the careful hands of an experienced endoscopist.

[The value of double contrast colon imaging in inadequate colposcopic diagnosis]

PURPOSE

Prospective evaluation of colon double-contrast enemas in patients with incomplete colonoscopy during routine examination.

MATERIALS AND METHODS

From 1. February 1993 through 31. January 1994 we prospectively evaluated all patients undergoing a double-contrast barium enema following incomplete colonoscopy in the endoscopy unit of the Department of Surgery of the University Hospital Marburg. The examination was carried out using the typical double-contrast technique at least 24 h after colonoscopy. The results of the barium enema were correlated with the findings at colonoscopy with regard to completion of the diagnostic procedure and additional pathological findings.

RESULTS

Of 448 colonoscopies 168 remained incomplete. Sixty patients underwent an additional double-contrast study of the colon. In 43 patients this study was sufficient to complete the diagnostic procedure. Unknown pathological diagnoses were found in 11 patients. In 2 patients an adenocarcinoma and in 9 patients polypoid lesions were detected.

CONCLUSION

After incomplete colonoscopy a double-contrast barium enema should be performed to complete the diagnostic examination of the whole colon and to reveal unknown additional pathological findings.

Nitinol prostheses for the treatment of inoperable malignant esophageal obstruction

PURPOSE

This uncontrolled prospective study was undertaken to evaluate a new nitinol stent in the treatment of dysphagia due to inoperable malignant esophageal obstruction.

PATIENTS AND METHODS

Eighteen consecutive patients (15 men, three women; mean age, 66 years +/- 15) with inoperable malignant obstructions of the esophagus or esophagogastric junction due to esophageal carcinoma (n = 14) or extrinsic obstruction (n = 4) were treated with self-expanding nitinol endoprostheses (diameter, 18 mm). Dysphagia score and activity index were assessed before and every 4 weeks after stent insertion.

RESULTS

Eighteen stents were deployed successfully. One stent expanded insufficiently and was removed inadvertently during retrieval of the application system. Mean time until complete expansion of the stent was 7.1 days +/- 5. Stent placement resulted in a significant decrease in the dysphagia score (2.7 +/- 0.7 before vs 0.6 +/- 0.7 after stent placement, P < .00005 by Wilcoxon matched-pairs test) and a significant increase in the activity index (2.6 +/- 1 before vs 1.7 +/- 0.9 after stent insertion; P < .005). There were no procedure-related complications. Follow-up period (mean, 155 days +/- 100) revealed recurrent dysphagia in four patients. Two patients experienced food bolus impaction, another two had tumor ingrowth through the mesh after 170 and 186 days. Fourteen patients died after a mean survival time of 158 days +/- 106, all with patent stents.

CONCLUSIONS

Self-expanding nitinol esophageal stents are safe and effective in the treatment of malignant esophageal obstructions.

Successful allotransplantation of microencapsulated parathyroids in rats

Allotransplantation of parathyroid tissue in humans is desirable for treating long-term hypoparathyroidism (e.g., after inadvertent removal of parathyroid glands during thyroid surgery). Until now, parathyroid allotransplantation was not used clinically because its advantages were outweighted by the need of immunosuppression. To overcome the immunogenicity of the tissue to be transplanted, we employed the method of microencapsulation; first tried in islet cell transplantation for experimental allotransplantation of parathyroid tissue. We have been able to achieve long-term success in a rat model. After isolation and tissue culture, tissue pieces from parathyroid glands of 280 Lewis rats were encapsulated in barium alginate and grafted into hypocalcemic DA rats. From the 7th to the 90th day after transplantation the recipient rats (DA rats) showed a normal serum calcium concentration. This is the first report of successful long-term survival and function of microencapsulated allotransplanted parathyroid tissue.

Incidence and clinical importance of perioperative histamine release: randomised study of volume loading and antihistamines after induction of anaesthesia. Trial Group Mainz/Marburg

Although histamine release is recognised as a common event during anaesthesia and surgery, few clinicians judge the resultant cardiorespiratory disturbances serious enough to warrant prophylaxis with antihistamines. We have assessed the incidence and importance of histamine release in a randomised 2 x 2 factorial study. 240 patients representing a routine throughput of major general surgery were studied during a standardised induction of anaesthesia and preoperative loading of the circulation with either Ringer solution or Haemaccel-35, with or without antihistamine prophylaxis with dimetindene (H1) plus cimetidine (H2). Cardiorespiratory disturbances were graded as detectable, clinically relevant, or life-threatening from observers' records of the anaesthesia and the actions taken by the anaesthetists. Disturbances that were accompanied by significant rises in plasma histamine were further designated histamine-related, and those that were not were designated histamine-unrelated. Anaesthetists, observers, and designators were blinded to whether or not the patients had received antihistamines and to which solution was used for circulatory volume loading. Clinically relevant or life-threatening histamine-related disturbances occurred in 8% of the patients who after induction of anaesthesia received Ringer without antihistamines, in 26% of those who received Haemaccel without antihistamines, and in 2% or less of those who received antihistamines (p < or = 0.0001). There were 4 life-threatening histamine-related disturbances, all in patients who received Haemaccel without antihistamines (p < 0.01). Histamine-unrelated disturbances occurred in 16% overall, with no obvious effect of Haemaccel or antihistamines. The histamine-related disturbances under anaesthesia were remarkable for their severity (even with small rises in histamine concentrations), for the prevalence of bradycardia, and for the absence of skin signs. Their likelihood and severity were increased in patients with tumours. The results of the trial make a case for routine prophylaxis with antihistamines as part of anaesthetic management.

[The initial results of the implantation of self-expanding nitinol stents into the esophagus in malignant dysphagia]

Nine patients (mean age 64, range 51-83 years), with dysphagia due to incurable malignant obstruction of the esophagus were treated by the introduction of 10 self-expanding metal endoprostheses (Nitinol stents). All cases were technically and functionally successful. In one patient the stent did not expand completely; it had to be removed and a second introduced. There were no other complications from the stent implantation. During the period of observation of 136 +/- 86 days one stent (11%) was reobstructed by tumor growing into the stent. Two patients died after 60 and 119 days, both with open stents. Early experience with the Nitinol stent indicates that good palliation of malignant dysphagia can be achieved with a much lower complication rate than results from tube implantation. The design and application system of the stent is capable of further improvement.

Perioperative nonspecific histamine release: a new classification by aetiological mechanisms and evaluation of their clinical relevance

As a consequence of the performance of a randomized controlled clinical trial on perioperative histamine release and cardiovascular and respiratory disturbances, several types of increases in plasma histamine had to be distinguished instead of only two which existed at the beginning of the study: drug-induced allergic and pseudoallergic reactions. First of all, the new classification by aetiology (clinical epidemiology) was derived from a meta-analysis (secondary analysis) of the most recent literature. According to that histamine release in the perioperative period has several, different causes and is involved in several, different disease manifestations. A clear distinction (classification), however, is necessary if histamine release as an unwanted (adverse) effect has to be recognized, value judged according to its clinical relevance and therefore also prevented by histamine antagonists. Histamine release by neuro-endocrine and neuro-inflammatory mechanisms, cytotoxic histamine release and local, cytokine induced histamine release have been distinguished from pseudoallergic histamine release, but its functions are not yet clear. It has been analysed in prospective trials which used special clinical situations as models: patients on a normal ward or before and during upper GI endoscopy without premedication, but also in specific phases of laparoscopic cholecystectomy (trocar phase and dissection phase). Their existence in the clinical reality is now very likely, but new trials must investigate the pathophysiological effects such as in metabolism, coagulation, pulmonary haemodynamics (shunt volume) and gastric acid secretion. Histamine release by pseudoallergic mechanisms, however, was identified in the very vulnerable post-induction phase of anaesthesia up to skin incision. Its incidence was much higher than ever expected and its clinical relevance was demonstrated by the severity of reactions and the intervention strategies of the anaesthetists who were blinded concerning the type of the plasma substitute given and the prophylaxis with antihistamines. Pseudoallergic histamine release was clearly unwanted (adverse). Its occurrence in the other phases of anaesthesia has to be further evaluated in the tedious procedure of data analysis of the Mainz-Marburg-trial. The overall incidence of histamine release in the trial was so incredible high (72% of all patients, some of them with up to 4 episodes of histamine release) that a distinction between pseudoallergic (unwanted) and other types of histamine release (possibly less unwanted or even beneficial) is urgently needed. In the phase of steady state (maintenance) of anaesthesia the H1-(+)H2-prophylaxis was highly effective. Further analysis must show whether this is also the case during the phases of induction of anesthesia.(ABSTRACT TRUNCATED AT 400 WORDS)