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Biomedical subjects

C Willy

Publications and source records attributed to C Willy.

At least 19 recordsLinked to original sources
PubMed2006

[Interface pressure measurement in the treatment of pressure sores. Comparison with subcutaneous pressure values measured in healthy volunteers].

BACKGROUND: Pressure relief is an important factor to determine the quality of anti-decubitus devices. Many studies have been carried out to measure the interface pressure, but because the results differed markedly, we made a study to assess the measurement devices. METHODS: The systems FSA, a device for internal use in the Lück company, the X-Sensor and an invasive subcutaneous pressure measurement over the os-sacrum (COACH: piezoelectric probe, MIPM) were tested on 20 healthy volunteers (average age 27 years, average BMI 21.8). RESULTS: The values of interface measurement showed obvious deviations from subcutaneous pressure in two cases (FSA +1.8%, Lück -33%, X-Sensor +65%) and some results showed extreme variations (FSA +18 mmHg, Lück -21 mmHg, X-Sensor +27 mmHg). CONCLUSIONS: The interface pressure measurement (with a few volunteers) is not suitable for a correct assessment of anti-decubitus devices. Furthermore, the use of this method is not necessary to monitor pressure relief in intensive care patients. These systems can, however be useful in the training of nursing staff.

Adult↗
PubMed2006

[Experimental principles of the V.A.C.-therapy -- pressure values in superficial soft tissue and the applied foam].

OBJECT OF THE STUDY: Measurement of the pressure during V.A.C.(R)-therapy in superficial parts of the affected soft tissue as well as at the soft tissue/foam-interface, measurement of pressure values along bigger distances in the foam and the comparison of pressure transfer between polyurethane and polyvinyl-alcohol foams. MATERIAL AND METHODS: A multi-channel electronic transducer-tipped catheter system based on the piezo-resistant principle was used. Measurement was performed on a plain table surface, at a bovine muscle as well as in human tibial anterior muscle of a patient after fasciotomy. Applied pressure values by V.A.C.(R)-therapy-units were 50 to 200 mm Hg (continuous suction modus). RESULTS: 100 % pressure transition through vacuum-therapy-foams to wound surface, almost 100 % pressure transition even along 60 cm in very large polyurethane-foams using only one trac-pad connector. Pressure values > 125 mm Hg using polyvinyl-alcohol-foams showed a reduction of up to 25 % in distances > 15 cm from trac-pad-connector. On the surface of the affected soft tissue there are negative and positive pressure values (25 % quartile: - 25 mm Hg; 75 % quartile: + 15 mm Hg). DISCUSSION: Pore walls of the foam can produce positive pressure conditions resulting in soft tissue compression and consecutively hypoperfusion or ischemia. V.A.C.(R)-therapy seems to produce an heterogeneity of pressure distribution at the wound ground leading to pressure gradients and facilitating drainage of interstitial fluid. This mechanism could explain the anti-edema effects of V.A.C.(R)-therapy resulting indirectly in an increased nutritive perfusion.

Animals↗
PubMed2005

[Indications and safety aspects of vacuum-assisted wound closure].

Problem wounds continue to challenge medical care. In recent times, good results have been achieved through the application of negative pressure wound therapy. This approach, known as vacuum-assisted wound closure (VAC) involves the use of a defined,controlled negative pressure over a polyurethane or polyvinyl sponge placed in the wound. The wound effluent is evacuated continuously. The result is an improvement of microcirculation, and wound healing is enhanced. Animal experiments have confirmed an increase in cell growth. The basis for surgical wound management continues to be appropriate debridement. In this connection, negative pressure therapy, as a supportive measure, has proved to have major advantages over traditional methods of wound management, advantages that need to be further investigated clinically and experimentally. Consideration of the safety aspects and risk factors associated with the procedure can contribute to the optimization of therapeutic safety.

Contraindications↗
PubMed2005

Intramuscular pressure, tissue oxygenation and EMG fatigue measured during isometric fatigue-inducing contraction of the multifidus muscle.

Simultaneous measurement of intramuscular pressure (IMP), tissue oxygen partial pressure (pO(2)) and EMG fatigue parameters in the multifidus muscle during a fatigue-inducing sustained muscular contraction. The study investigated the following hypotheses: (1) Increases in IMP result in tissue hypoxia; (2) Tissue hypoxia is responsible for loss of function in the musculature. The nutrient supply to muscle during muscle contraction is still not fully understood. It is assumed that muscle contraction causes increased tissue pressure resulting in compromised perfusion and tissue hypoxia. This tissue hypoxia, in turn, leads to muscle fatigue and therefore to loss of function. To the authors' knowledge, no study has addressed IMP, pO(2) and EMG fatigue parameters in the same muscle to gain a deeper sight into muscle perfusion during contraction. As back muscles need to have a constant muscular tension to maintain trunk stability during stance and locomotion, muscle fatigue due to prolonged contraction-induced hypoxia could be an explanation for low back pain. Sixteen healthy subjects performed an isometric muscular contraction exercise at 60% of maximum force until the point of localized muscular fatigue. During this exercise, the individual changes of IMP, pO(2) and the median frequency (MF) of the surface EMG signal of the multifidus muscle were recorded simultaneously. In 12 subjects with a documented increase in intramuscular pressure, only five showed a decrease in tissue oxygen partial pressure, while this parameter remained unchanged in six other subjects and even increased in one. A fall in tissue pO(2) was associated with a drop in MF in only five subjects, while there was no correlation between these parameters in the other 11 subjects. To summarize, an increase in IMP correlated with a decrease in pO(2) and a drop in MF in only five out of 16 subjects. High intramuscular pressure values are not always associated with a hypoxia in muscle tissue. Tissue hypoxia is not automatically associated with a median frequency shift in the EMG signal's power spectrum.

Adult↗
PubMed2005

[Clinical results with A new retrograde femoral nail with a radiographical-free proximal locking device. A prospective study with 50 fractures].

INTRODUCTION: Conventional retrograde nailing of the femur causes two important disadvantages: the proximal locking of the nail is difficult because of the anatomic conditions and a chondral defect was left into the knee. MATERIAL AND METHODS: After the retrograde implantation the new nail was lead through the greater trochanter. An additional proximal aiming device for proximal interlocking can be fixed. The entrance portal will be sealed by an osteochondral cylinder. 50 cases of femur fractures were selected for the prospective study. We recorded all intraoperative complications and technical difficulties. The cases were followed up for 52 weeks, both clinical and radiology examinations were performed. RESULTS: The mean follow up was 15.5+/-5 months. All fractures were healed. Knee movement was 125+/-14 degrees. The Leung Score was 84+/-12.6 points; HSS Score was 90+/-9 points. In two cases wound infections were developed. Mal-union was observed in three cases, in two cases nail brake down. CONCLUSIONS: The new retrograde interlocking nail could be used to manage femur fractures successfully. Two aiming devices enable a easy interlocking. Replacement of the osteochondral cylinder into the entry portal reduces cartilage damage.

Adolescent↗
PubMed2004

[Treatment of trans-symphyseal instability with an internal fixator. Outcome of a surgical technique on the basis of a case report].

Treatment of traumatic trans-symphyseal instability by internal plate fixation is the most common procedure. Besides the trauma-induced muscle damage, the implantation induces additional damage at the symphyseal origin of the m. rectus abdominis. The aim of this clinical case study was to examine whether it is possible to reduce the iatrogenic soft tissue damage while correcting trans-symphyseal instability using an internal fixator. After a transverse skin incision, two pedicle screws were drilled into the corpus ossis pubis next to the symphysis. Afterwards the crossbar was implanted and fixed. Generally, implantation of two self-trapping pedicle screws using a skin incision with a length of 6 cm is possible. Additional detachment of the m. rectus abdominis is not necessary. As a result of the mobility of the skin and subcutaneous tissue, the implantation of the crossbar beneath the m. rectus abdominis is possible. Stabilization of traumatic trans-symphyseal instability by internal fixation is a safe and easy method. Additional soft tissue damage can be prevented, but to achieve multidirectional stability some small modifications of the implant are necessary.

Bone Plates↗
PubMed2004

[Pressure conditions under VVS-foams - an experimental in-vitro- and in-vivo-analysis].

The aim of this study was to determine the pressure conditions in the tissue beneath and on the surface of wounds. This was done in vitro both on a plain surface and on a bovine muscle. In comparison we measured the pressure of the anterior tibial muscle of a patient with compartment syndrome. Besides, we applied negative pressure using just one drape connector and measured the pressure in different distances to look if the pressure is constant in large V.A.C.(R) dressings. Both polyurethane and polyvinyl alcohol foams were used.

Animals↗
PubMed2003

[Drainage in soft tissue surgery. What is "evidence based"?].

Due to the advanced technical possibilities, there are now up to 30 different drainage systems available for soft tissue surgery. The differences between these systems involve the mode of drainage (open into the bandage, closed into bag/bottle), the kind of suction (gravity drainage, low-vacuum and high-vacuum up to 900 mbar) and the material of the tube (PVC, silicone or polyurethane). There also exists a marked controversy about the fundamental necessity for drainage after surgery. A survey of the literature indicates that there is a distinct discrepancy between scientific knowledge and daily routine action. For primarily uninfected wounds, the application of an open drainage system,with the secretion going directly into the bandage, is obsolete. Gravity drainage systems guarantee just as effective secretion drainage in comparison to high vacuum drainage according to Redon. In soft tissue wounds, high-vacuum suction leads to the sucking in of tissue and blood,whereby comparatively elevated quantities of secretion can be produced. During the removal of Redon-drainage, there is stronger pain than on the removal of gravity drainage systems consisting of silicone or polyurethane. Prophylactic insertion of drainage in uncomplicated thyroid surgery and for hernia repair is not necessary. Insertion of drainage for up to 72 h is not accompanied by an elevated infection rate. The routine microbiological examination of the tip of the drainage tube is not recommended.

Drainage↗
PubMed2001

[Intracompartmental pressure measurement in in acute compartment syndrome. Results of a survey of indications, measuring technique and critical pressure value].

The early diagnosis of acute compartment syndrome is very important, compartment monitoring is advocated. There is however still some controversy regarding the use of compartment pressure measurement devices in the diagnosis of acute compartment syndrome. We present the results of a survey that was designed to explore this issue in Germany. In the case of suspected acute compartment syndrome 50.9% (n = 214) of the surgeons perform intracompartmental pressure measurement. Pressure measurement is of lower significance for 61.8% (n = 215) surgeons questioned. Additional apparative diagnostics is performed by 41.7% of the surgeons. A large majority apply the Stryker device (63.1%, n = 135), followed by the Coach device (12.1%, n = 26). The pressure threshold for intervention is recommended by 51.4% (n = 110) of the traumatologists as an absolute compartment pressure value. The remaining 48.6% (n = 104) include haemodynamic parameters in their decision. The surgeons employ widely differing methods of approach in the diagnosis of acute compartment syndrome. Some of these are extremely different from the methods recommended in the literature.

Acute Disease↗
PubMed2001

[Radiation and burn trauma (combined injury). Considerations in surgical treatment].

Combined injury syndrome (CIS) is defined as mechanical and/or thermal trauma associated with radiation injury. Each of these injuries is characterized by several systemic reactions, influencing especially the immune system and fluid balance. Experiences gained during World War II, the clinical observations after radiation accidents and experimental studies demonstrate that CIS can be considered as an own entity of disease characterized by increased mortality due to additive effects of the combined injuries. Up to now, our knowledge concerning the pathomechanisms of combined injuries is not sufficient. Nevertheless, there is a growing body of evidence that two basically different effects compromise organ function: (i) resembling or identical reactions of each trauma type simply added up to an increased systemic damage and (ii) posttraumatic alterations, where the effect of one kind of trauma synergistically increases the totally different effect of the other. Due to the associated acute radiation syndrome and the special pathophysiology of CIS, surgical treatment has to be considerably different from that of conventional multiple injured patients. Initial surgical procedures must be completed during the short time period of 48-72 h before onset of radiation-induced neutropenia and thrombocytopenia. This includes primary wound closure, management of all the abdominal, thoracical and vascular injuries as well as definite osteosynthesis. Later, all invasive procedures must be avoided due to the high risk of opportunistic infections and possible massive hemorrhage. When hematopoietic recovery begins, subsequent steps of surgical treatment can be taken into consideration. However, it is important, that as in conventional trauma, resuscitation and emergency care have priority and should be performed independent of the degree of radiation injury.

Burns↗
PubMed2001

[Acute compartment syndrome. Results of a clinico-experimental study of pressure and time limits for emergency fasciotomy].

BACKGROUND: Acute compartment syndrome of the leg is to be regarded as a traumatological emergency. Most specialists already agree that only a timely operative decompression of the afflicted compartment can prevent serious tissue damage. What still remains subject to discussion, however, is the precise tissue pressure above which the operation becomes imperative. Experimental human studies focusing on tissue pressure and muscle oxygenation have not yet been carried out. It was thus the aim of the present study to analyze oxygen partial pressure of the anterior tibial muscle and peroneal action potential in a model compartment syndrome in man. METHODS: In 22 healthy, normotensive volunteers, constant pressure values from 0 to 100 mmHg were induced in the anterior tibial muscle with antishock trousers. Over a period of up to 6 h measurements were made of (1) tissue pressure, (2) intramuscular oxygen partial pressure (pO2), and (3) muscle response potential (MRP) of the n. peroneus profundus by electroneurography. RESULTS: We achieved a 97.7% (Q25%/Q75%: 89.2/99.8) transfer of the pneumatic pressure to the lower leg. Already at intramuscular tissue pressures of 30-40 mmHg, hypoxia and reduction of MRP appeared. A reduction of the MRP to zero and pO2 < 1 mmHg was observed from a pressure of 50 mmHg. Tissue pressure values of over 75 mmHg resulted almost without exception in anoxia of the muscle. CONCLUSIONS: Even under normal perfusion conditions, already slight increases in pressure of above 30 mmHg lead to reduced tissue oxygenation and neural function. We have to consider that with additionally traumatized muscle the ischemic tolerance is markedly reduced and due to unknown influences such as local vasoreactivity and capacity of autoregulation the nutritive perfusion cannot be determined. In the case of a severely injured muscle, to be on the safe side decompressive fasciotomy should therefore be carried out if pressure values remain above 30 mmHg.

Adult↗
PubMed2001

Transforming growth factor-beta1-induced Smad signaling, cell-cycle arrest and apoptosis in hepatoma cells.

Transforming growth factor-beta1 (TGFbeta) is involved in the regulation of liver cell proliferation and apoptosis, and escape of hepatoma cells from the growth restraining signals of TGFbeta has been suggested to contribute to tumor development. TGFbeta modulates gene transcription by receptor-mediated activation of Smad proteins which act as transcription factors. TGFbeta-mediated primary signaling responses as well as effects on the cell cycle and apoptosis were investigated in the human hepatoblastoma line HepG2, the rat hepatoma line FTO-2B and the mouse hepatoma line 55.1c. Activation of a Smad (Sma and Mad homolog) response-element-driven luciferase reporter by TGFbeta was very similar in all three cell lines, indicating functionality of the primary TGFbeta signaling pathway. Moreover, TGFbeta-inducible early gene was transiently activated by TGFbeta in all cell lines as shown by RT-PCR. HepG2 cells, however, were completely resistant to TGFbeta-induced growth arrest and apoptosis and 55.1c cells were only slightly susceptible to TGFbeta-induced apoptosis. By contrast, treatment of FTO-2B cells with TGFbeta led to a partial G0/G1 arrest and a strong induction of apoptosis. TGFbeta-induced apoptosis of FTO-2B cells was inhibited by dexamethasone, insulin, phenobarbital and dieldrin. Of these agents, only insulin led to a significant reduction of TGFbeta-stimulated Smad-reporter activity, suggesting that the other compounds interfere with TGFbeta-induced apoptosis downstream of Smad-mediated primary transcriptional responses at a level that may be constitutively altered in apoptosis-resistant hepatoma cell lines.

Apoptosis↗
PubMed2001

Complexity and non-linearity in shock research: reductionism or synthesis?

The various analytical techniques used to explain the many supposed mediators of sepsis and septic shock have outpaced the integrative approaches that simplify this complexity for the physiologist and the clinician. In this article we discuss the pros and cons of reductionism and its limitations in the field of shock research and emphasize the need for synthesis research. Taking account of the historical development of natural science, we will discuss the question of how far a reductionist approach can help to explain biological phenomena and conclude that reductionism, although essential to the scientific process, reduces the evidence absurdity if exaggerated. The part is never the whole, and it is impossible to understand the whole through limited dissections of its parts. The understanding of complex systems requires approaches other than those of explanatory reductionism. We emphasize a different approach-systems thinking. Systems scientists are not interested in the underlying components; they describe and characterize complex relations. Other disciplines that use systems thinking should be studied. However, to follow the concept of synthesis, reductionists must describe the components of the system. Reductionism and synthesis are therefore the two sides of a coin. Professional synthesis research is a serious challenge in shock research.

Animals↗
PubMed2000

DNA damage in human leukocytes after ischemia/reperfusion injury.

Leukocytes have been shown to play an important role in the development of tissue injury after ischemia and reperfusion (I/R). In the present study, the effects of tourniquet-ischemia on induction of DNA damage in peripheral leukocytes and on respiratory burst of neutrophils in humans were examined. The DNA damage was measured as increased migration of DNA using the single-cell gel-electrophoresis technique (comet assay). Intracellular production of reactive oxygen species by neutrophils was measured flow-cytometrically using dihydrorhodamine 123 as indicator. Postischemic, significantly increased migration of DNA was found in leukocytes of 20 patients (tourniquet-ischemia of the lower limb for 65-130 min, anterior-cruciate-ligament-reconstruction) and in 10 experiments (1 volunteer, repeated tourniquet-ischemia of the upper limb for 60 min, no operation). DNA effects were most pronounced 5-30 min after tourniquet release, and then declined over a 2 h period, but did not return to preischemic baseline values. A similar time course showed the oxidative status of unstimulated granulocytes during reperfusion. Simultaneously, opposing changes were measured in formyl peptide (f-MLP)- or phorbol ester (PMA)-stimulated granulocytes, which showed a significantly declined respiratory burst reaction after tourniquet-release indicating preactivation of neutrophils by IR. Our data suggest that IR induces genotoxic effects in human leukocytes presumably in response to oxidative stress during reperfusion.

Adult↗
PubMed2000

The chronic venous compartment syndrome.

BACKGROUND: A chronic exertional compartment syndrome has only been observed in athletes and soldiers. In the vast majority, the disease affects the anterior compartment and the fibular muscle group, and only rarely the lateral and dorsal muscle compartments. Muscle tissue necrosis does not occur. In the course of venous diseases with a severe chronic venous stasis syndrome, a chronic venous compartment syndrome develops that differs considerably from the familiar functional syndrome. The predominant symptom is an uncurable cuff ulceration on the lower leg. PATIENTS AND METHODS: From 1993 to 1996 a total of 16 patients with a chronic fascial compression syndrome underwent surgery on 18 extremities. The crural fascia was resected and a mesh graft was applied. RESULTS: In the group of ten controls with healthy veins the average pressure in the deep compartment was 13.6 mmHg (range 9-17 mmHg) lying down and 29.9 mmHg (range 15-42 mmHg) standing up. In 14 patients with chronic fascial compression syndrome, the average pressure was higher, measuring 21.1 mmHg (range 8-47 mmHg) lying down and 62.5 mmHg (range 33-87) standing up. After surgery, the pressure dropped to 15.5 mmHg (range 5-24 mmHg) lying down and 34.5 mmHg (range 10-58 mmHg) standing up, but did not fall as low as the average values recorded in the control group or in the patient's healthy leg. The results from the standing up position were statistically significant (p = 0.003). Computed tomography showed major changes in the muscles indicating muscle atrophy and fatty degeneration. The crural fascia seemed to be incorporated in the scars of the subcutaneous tissue in large areas. After crural fasciectomy and healing of the ulceration, the tissue structure of the muscles recovered. CONCLUSIONS: In chronic fascial compression syndrome, the trellis arrangement of the collagen fibres becomes disordered. This results in a loss of flexibility during muscle contraction. Every step causes an increase of intracompartmental pressure and microstructural injury. The consequence is resection of the crural fascia.

Amputation, Surgical↗
PubMed2000

Leukocyte depletion of red cell components prevents exposure of transfusion recipients to neutrophil elastase.

BACKGROUND: Polymorphonuclear leukocytes contain a large number of enzymes and bactericidal proteins stored in granules. Neutrophil activation induces degranulation and immediate release of these bioactive substances, including human neutrophil elastase (HNE) also known as elastase-2 (ELA2), which may contaminate whole blood units and blood components. MATERIALS AND METHODS: The HNE concentration was determined in the supernatants of blood components with a commercial enzyme-linked immunosorbent assay (ELISA). The effect of leukocyte depletion and storage was evaluated by testing whole blood, buffy-coat-reduced, and leukocyte-depleted red cell units. Buffy-coat-derived platelets and plasma were also tested. RESULTS: HNE concentrations at day 1 were about 50 microg/l in all types of red cell components with the exception of leukocyte-depleted red cells (<0.26 microg/l). In leukocyte-depleted red cells, platelets and plasma, no significant increase was observed during storage. In whole-blood units and buffy-coat-reduced red cells, the HNE concentrations increased steadily and often exceeded 1,000 microg/l when the units expired. CONCLUSION: Leukocyte depletion may limit the inadvertent infusion of bioactive substances derived from polymorphonuclear leukocytes, of which HNE is but one example. The accumulation of HNE in buffy-coat-reduced red cells may be greater than that of whole blood units. HNE accumulates during storage and its quantity may have pathophysiologic significance. Platelets and plasma derived from buffy coats contain some HNE, but leukocyte-depleted red cells virtually none. However, we consider the accumulation of HNE in these components not to be clinically important. The quantities, kinetics, and occurrence in various blood components of HNE contamination differ from those observed with cytokines.

Biological Assay↗