Pathogenesis of chronic venous insufficiency by obesity

Obesity (body mass index: BMI ≥30 kg/m2) is named as a risk factor for chronic venous insufficiency (CVI) in phlebologic studies, even though the mechanisms of effects are still unclear. Therefore we examined literature for current data and hypotheses and described them.

On the one hand, the correlation between obesity and CVI is explained by chronically inflammatory processes, affected by the lipometabolism of obese and the metabolic syndrome. On the other hand, this particular correlation is explained by a mechanical approach based on an elevated intraabdominal pressure (IAP), which is transmitted to the venous system of the lower extremities. Recent studies show that the chronically inflammatory processes promote the frequency and manifestation of thrombosis. In regard to the IAP, only the pressure of the elevated abdominal mass (paunch) seems to have a minimal effect in the supine position.

Several studies relativised the correlation between obesity and CVI because of the rising prevalence of venous disease with age, which correlates with a higher BMI as well. Furthermore, studies have shown the phenomena of so-called venous hydrostatic ulcerations in obese patients. That means those patients show the typical skin changes of the CVI without any venous reflux. Depending on the study, their proportion is estimated between 21% and 64% of venous leg ulcers. Additionally, it was shown that after weight loss the skin seems to regenerate from the typical signs of CVI. At the moment, the pathomechanism causing hydrostatic ulcers in obese is unclear.

Dorsal venous foot ulcer caused by an intermetatarsal perforating vein

This case report describes a woman (age: 79 years) with a recurrent venous ulcer located on the left dorsal foot. Duplex investigation showed that this ulcer was caused by an intermetatarsal insufficient perforating vein (PV). Finally Duplex-guided sclerotherapy of the causing PV has been chosen as therapy and the ulcer was successfully healed.

Aktive Bettruhe als Begleitmaßnahme für die erfolgreiche Chirurgie des Ulcus cruris venosum

Die aktive Bettruhe ist ein operationsbegleitendes Therapiekonzept bei Ulcus cruris venosum, zur präoperativen Konditionierung und postoperativen Konsolidierung. Ziel dieses Therapiekonzepts ist es, unter Bettruhe mit Beinhochlagerung und einem gezielten Trainingsprogramm optimierte Operationsbedingungen schaffen und das Therapieergebnis positiv zu beeinflussen. Patienten, Methoden: 88 Patienten (118 Beine) wurden mittels aktiver Bettruhe operationsbegleitend konditioniert. Neben der Methode werden klinischen Charakteristika, Compliance und Abheilungs-, Rezidiv- und Komplikationsrate beschrieben. Ergebnisse: Die aktive Bettruhe erfolgte durchschnittlich sieben Tage (Spannweite 1–38). Die Compliance hinsichtlich Zumutbarkeit und Nachvollziehbarkeit war sehr hoch. Eine hohe Abheilungs- und geringe Rezidiv- und Komplikationsraten unterstreichen die Bedeutung eines umfassenden Therapiekonzepts. Schlussfolgerung: Die Aktive Bettruhe eignet sich vor allem zur Schaffung optimaler Operationsbedingungen mit klinisch relevantem Einfluss auf das Gesamtergebnis sowie zur Steigerung der Compliance des Patienten mit einem sekundär-präventiven Effekt.

Lateral Fasciectomy Sparing the Superficial Peroneal Nerve with Simultaneous Mesh Graft in Non-healing Lateral Leg Ulcers of Diverse Vascular Origins: Surgical Technique, Short- and Long-term Results from 44 Legs

OBJECTIVES

The technique of lateral fasciectomy (LF) sparing the superficial peroneal nerve with mesh graft coverage is a novel treatment of non-healing lateral leg ulcers of various vascular origin affecting the fascia. We report short- and long-term results of LF for recalcitrant lateral leg ulcers.

DESIGN

This study is a single center, retrospective case series of consecutive patients treated by LF.

MATERIALS

From 827 ulcers treated at our institution, 44 recalcitrant lateral leg ulcers affecting the fascia (41 patients) underwent lateral fasciectomy between 2006 and 2013.

METHODS

Preoperative indications, step-by-step surgical procedures, and perioperative care methodologies are presented. Long-term effects of healing and recurrence were clinically investigated or obtained through telephone interviews with relatives and local practitioners.

RESULTS

Three discrete etiologies were identified: venous ulcers (n = 24), arterial-venous/mixed ulcers (n = 11), and arteriolar Martorell hypertensive leg ulcers (n = 9). Complete healing was achieved in 40 legs (91%) after 3 months, and in 43 of the affected legs (98%) in total. The median duration to complete healing was 64 days. There was no difference between the healing times of different etiologies. No local recurrence was observed during the follow-up period, which ranged from 1.8 to 8.7 years (median: 5.11, mean: 5.12). Twelve patients (27%) died within this period due to multimorbidity.

CONCLUSIONS

Following lateral fasciectomy and mesh graft coverage, 43 legs (98%) healed in previously treatment resistant lateral leg ulcers.

Different approaches for modelling of sewer caused urban flooding

The correct prediction of flooding in urban areas is an important challenge to secure the values and fulfil public regulations. Traditional sewer simulations deliver the basic information for a rudimental flood protection, but the interaction between sewer and surface runoff can only be considered by a bi-directional modelling. Therefore detailed information about the relevant structures on the surface is necessary, which can partially be delivered by airborne laser scan data. This data have to be refined to get as detailed information about the endangered areas as possible. But the plenitude of information leads to high requirements on computer capacity and performance. This paper shows different approaches to predict the sewer caused flooding in urban areas. The approaches have been checked on two testing areas in Germany and the developed tool will be implemented in a commercial software system soon. This approaches, which partially base on each other, make a stepwise refinement of the model and narrowing of the affected areas possible. The developed algorithms to thin the digital terrain model and the well proven method to parallelize the calculation on more than one processing units secure an effective calculating process.

Postembryonic fast muscle growth of teleost fish depends upon a nonuniformly distributed population of mitotically active Pax7+ precursor cells

Muscle development in teleost embryos has been shown to depend on myogenic cell recruitment from the dermomyotome (DM). However, little is known as to the cellular mechanisms that account for myotome growth after the dissociation of the DM. Here we combine immunolabeling for cell-specific markers with quantitative analysis to determine the sources and patterns of activation of myogenic cells in pearlfish larvae. Results demonstrate that appearance of mitotically active myogenic precursors inside the myotome coincides with the dissociation of the DM. Such cells are preferentially aggregated within the posterior lateral fast muscle. We therefore propose a growth model in which a pool of proliferative DM-derived precursors transferred to the posterior lateral fast muscle functions as an important source of myogenic cell spread to carry forward stratified fast muscle hyperplasia. This indicates that postembryonic teleost muscle growth includes a cellular mechanism that has no direct equivalent in the amniotes.

Venous reflux surgery promotes venous leg ulcer healing despite reduced ankle brachial pressure index

AIM

The aim of this study was to demonstrate that venous surgery promotes ulcer healing, even in the presence of peripheral arterial disease.

METHODS

In this retrospective study, 33 patients (49 legs) with venous leg ulcers and reduced arterial ankle brachial pressure index (< or = 0.8) were followed up 3 months to 7 years (median: 3.11 years) after venous surgery (group I). Venous reflux was considered to be the main cause of ulceration, and no attempt was made to restore the arterial circulation. The results were compared with those of patients with ulcers without arterial occlusive disease (n=190) who were treated following the same principles (group II). The surgical procedure consisted of interruption of reflux in the superficial and/or perforating veins. Additionally, shaving, fasciectomy, and mesh grafting was performed in 36 cases.

RESULTS

In group I, 21 legs were lost to follow-up, 16 due to death. The mortality rate was three times higher in group I than in group II. From 28 legs of group I seen after 0.4-6.7 years (median: 2.9 years), 19/28 legs (68%) were healed compared with 123/145 (85%) in group II after 0.2-7.2 years (median: 3.2 years) (not significant [NS]). Group I showed a significantly longer healing time than group II (P<0.05) (P<0.001). Recurrence was observed in 3/28 (11%) from group I and in 6/145 (4%) from group II (NS). The time course of recurrence showed no statistically significant difference between the groups.

CONCLUSION

Venous surgery produces beneficial results not only in pure venous ulcerations, but also in patients with accompanying arterial disease.

MyoD and Myogenin expression during myogenic phases in brown trout: a precocious onset of mosaic hyperplasia is a prerequisite for fast somatic growth

Muscle cell recruitment (hyperplasia) during myogenesis in the vertebrate embryo is known to occur in three consecutive phases. In teleost fish (including zebrafish), however, information on myogenic precursor cell activation is largely fragmentary, and comprehensive characterization of the myogenic phases has only been fully undertaken in a single slow-growing cyprinid species by examination of MEF2D expression. Here, we use molecular techniques to provide a comprehensive characterization of MyoD and Myogenin expression during myogenic cell activation in embryos and larvae of brown trout, a fast-growing salmonid with exceptionally large embryos. Results confirm the three-phase pattern, but also demonstrate that the second and third phases begin simultaneously and progress vigorously, which is different from the previously described consecutive activation of these phases. Furthermore, we suggest that Pax7 is expressed in myogenic progenitor cells that account for second- and third-phase myogenesis. These findings are discussed in relation to teleost myotome development and to teleost growth strategies.

Lebensqualität von Patienten mit Ulcus cruris venosum nach funktioneller Phlebochirurgie

Ziel: Messung der Lebensqualität (LQ) begleitend zur operativen Behandlung um festzustellen, ob diese für Patienten mit therapieresistenem Ulcus cruris venosum/mixtum, die neben einem hohem Durchschnittsalter zahlreiche Nebendiagnosen aufweisen, indiziert ist. Patienten, Methoden: Die prä- und postoperativen Daten von 120 Patienten (169 Beine) umfassen neben klinischen Charakteristika die Instrumente zur LQ-Messung, z. B. NHP (Nottingham Health Profile), VAS (Visual Analogue Scale), allgemeinen subjektiven Gesundheitszustand. Ergebnisse: Der NHP, VAS und allgemeine Gesundheitszustand zeigten eine statistisch signifikante Verbesserung zwischen dem prä- und postoperativen Zustand. Die größten präoperativen Einschränkungen der LQ betrafen den Bereich Schmerzen. Die hohe Patientenzufriedenheit drückte sich darin aus, dass 95% der Patienten angaben den Eingriff nicht zu bereuen. Schlussfolgerung: Im Falle der untersuchten Patienten stellt die chirurgische Ulkustherapie eine adäquate Behandlungsmethode dar, die zu signifikanter Verbesserung der Lebensqualität führte.

[Critical infusion incident caused by incorrect use of a patient-controlled analgesia pump]

We report on the case of a 17-year-old male patient who received a PCA pump after nephrectomy for postoperative analgesia. The syringe of the PCA pump was filled with 50 mg morphine and positioned about 25 cm above the heart. Since the piston of the syringe was not bolted while the pump was switched off, an unnoticed accidental evacuation of the whole content of the syringe into the intravenous line of the patient occurred because of gravity. This problem exists not only with PCA pumps, but can happen with syringe pumps in general. The incident, which can only be explained by strongly reduced venous pressure, was detected by chance. No harm resulted for the patient, but under different conditions it could have been lethal. This critical incident was caused by various factors: incorrect application in combination with insufficient experience or training, stress, inadequate handing-over of the patient and a lack of arrangements and instructions for procedures in routine situations. Suggestions for preventing such dangerous critical incidents are made and discussed. In particular, an algorithm for the correct procedure when inserting or changing the syringe of a syringe pump is presented.

[Simulation as a method for solving medical technical problems]

The present paper first presents a comprehensive overview of the methodological aspects of simulation. It lists the various approaches to the modelling of real-world systems and emphasizes the respective constraints on the interpretation of model data. For this purpose, a classification of typical applications of simulation models is given, and is followed by a discussion of three structurally different ways of constructing a model. The correct matching of these modelling concepts to the particular application problem in hand is discussed, with special consideration being given to the drawing of conclusions from, and the interpretation of, the simulation results. To round of the classification, the simulation models are differentiated in accordance with the nature of their implementation. By defining application type, modelling concept and model implementation, an understanding of the validity and appropriate application of any industrial model is derived.

[Development of a mathematical model for simulation of artificial ventilation]

This article describes a mathematical model for the simulation of artificial ventilation employing only the figures for air pressure and air flow between respirator and lungs. A discussion of methodological aspects of the problem shows that the model of the respiratory system can be reduced to an equivalent circuit diagram comprising only resistances and capacitances. The structure of the mathematical model is oriented to the elements of the real respiratory system, and its modularity permits ready adaptation to a variety of real-life situations. Particular emphasis was placed on the correct parametrization of the model with the aid of data originally collected from physical experiments. Finally, some selected model runs that demonstrate the range of validity and the accuracy of the model are presented.

[Measurement of O2 concentration in the fresh gas supply of the Kuhn system]

To accomplish the requirement of inspiratory O2-concentration measurement on the Ayre-T-piece modified by Kuhn we developed a special device. It is mounted in the fresh gas hose and then connected to the sensor of the O2-concentration measuring and warning instrument of the circle system.

[Comparative studies of CPAP systems using a respiration simulator. I. Evaluation criteria]

Assessment of the performance of modern ventilators that combine spontaneous breathing and mechanical ventilation is orientated not only towards the assessment of the inspiratory and expiratory resistance within the system, but also towards the functional criteria for the inspiratory and expiratory valves. This conclusion is particularly valid for CPAP procedures, as in this case patients must perform the entire work of breathing by themselves. As it has proved to be extremely problematic to carry out comparative testing of ventilators on patients in the intensive care unit, a breathing simulator has been developed, the use of which has enabled us to have a "patient" at our disposal who can tolerate the procedures for measuring the performance of ventilators with IMV and with CPAP without injury. The pressure-flow characteristics and the work of breathing can thus be measured under constant conditions and with various ventilation systems. Exact analysis of the pressure curve pattern under standardized conditions proved to be of value for assessing the suitability of CPAP in the case of both demand-valve systems and continuous flow systems. Appropriate assessment criteria have been worked out; the course of the test and the results for two ventilators are discussed as an example, using these criteria.