Atom Interferometry in a Warm Vapor.

We demonstrate matter-wave interference in a warm vapor of rubidium atoms. Established approaches to light-pulse atom interferometry rely on laser cooling to concentrate a large ensemble of atoms into a velocity class resonant with the atom optical light pulse. In our experiment, we show that clear interference signals may be obtained without laser cooling. This effect relies on the Doppler selectivity of the atom interferometer resonance. This interferometer may be configured to measure accelerations, and we demonstrate that multiple interferometers may be operated simultaneously by addressing multiple velocity classes.

From intra- to extra-uterine: early phase design of a transfer to extra-uterine life support through medical simulation.

Introduction: Extra-uterine life support technology could provide a more physiologic alternative for the treatment of extremely premature infants, as it allows further fetal growth and development ex utero. Animal studies have been carried out which involved placing fetuses in a liquid-filled incubator, with oxygen supplied through an oxygenator connected to the umbilical vessels. Hence, by delaying lung exposure to air, further lung development and maturation can take place. This medical intervention requires adjustments to current obstetric procedures to maintain liquid-filled lungs through a so-called transfer procedure. Methods: Our objective was to develop obstetric device prototypes that allow clinicians to simulate this birth procedure to safely transfer the infant from the mother's uterus to an extra-uterine life support system. To facilitate a user-centered design, implementation of medical simulation during early phase design of the prototype development was used. First, the requirements for the procedure and devices were established, by reviewing the literature and through interviewing direct stakeholders. The initial transfer device prototypes were tested on maternal and fetal manikins in participatory simulations with clinicians. Results & discussion: Through analysis of recordings of the simulations, the prototypes were evaluated on effectiveness, safety and usability with latent conditions being identified and improved. This medical simulation-based design process resulted in the development of a set of surgical prototypes and allowed for knowledge building on obstetric care in an extra-uterine life support context.

Transcardial perfusion fixation of the CNS by means of a compressed-air-driven device.

In the present report we describe the construction of a systemic vascular perfusion device designed to perfuse small mammals with fixatives under a constant, controlled hydrostatic pressure. The device is powered by compressed-air. The construction of the device allows the interchange of vessels containing various perfusates during the perfusion, without having to interrupt the flow or alter the hydrostatic pressure. Large volumes of fixatives can be perfused in a relatively short time, leading to good preservation of brain tissue, both for light and electron microscopical purposes.

Measurement of intracompartmental pressure with use of a new electronic transducer-tipped catheter system.

Laboratory and clinical tests were carried out to determine the clinical usefulness, validity, and safety of a new self-calibrating, battery-powered monitoring system for the measurement of intramuscular pressure with use of an electronic transducer-tipped catheter. The eight probes accurately recorded applied pressures ranging from zero to 160 millimeters of mercury (zero to 21.33 kilopascals). The system registered little temperature-induced drift (maximum, 1.25 millimeters of mercury [0.17 kilopascal]) between dry room temperature and 40 degrees Celsius. There were also minimum variations (range, -0.14 to 0.81 millimeter of mercury [0.02 to 0.11 kilopascal]) in the pressures recorded during a twenty-four-hour period. The resting pressure in the tibialis anterior muscle of twenty volunteers who had normal limbs was a mean (and standard deviation) of 13.1+/-8.3 millimeters of mercury (1.75+/-1.11 kilopascals). There was a good correlation between externally applied pressures (zero, twenty, forty, sixty, eighty, and 100 millimeters of mercury [zero, 2.67, 5.33, 8.00, 10.66, and 13.33 kilopascals] applied with use of antishock trousers) and the pressures measured in the tibialis anterior muscle of four volunteers (r = 0.997 to 0.999). The injection of sterile saline solution into the tibialis anterior muscle of a volunteer and the use of high-frequency recording during muscular activity showed a high degree of responsiveness and sensitivity to changes in intramuscular pressure. We also prospectively evaluated the clinical usefulness of the system and found it to be easy to assemble, calibrate, and use. Thus, this reusable, electronic transducer-tipped catheter system, which is based on a noninfusion technique, is simple, minimally traumatic, and highly precise. It is free of hydrostatic pressure artifacts and provides dynamic responses to changes in intramuscular pressure.

Step and ramp induction of myocardial ischemia: comparison of in vivo and in silico results.

This study tested the robustness of our computational model of myocardial metabolism by comparing responses to two different inputs with experimental data obtained in pigs under similar conditions. Accordingly, an abrupt and a gradual reduction in coronary flow of similar magnitude were implemented and used as model input. After flow reductions reached 60% from control values, ischemia was kept constant for 60 min in both groups. Our hypotheses were that: (1) these two flow-reduction profiles would result in different transients (concentrations and flux rates) while having similar steady-state values and (2) our model-simulated responses would predict the experimental results in an anesthetized swine model of myocardial ischemia. The two different ischemia-induction patterns resulted in the same decrease in steady-state MVO2 and in similar steady-state values for metabolite concentrations and flux rates at 60 min of ischemia. While both the simulated and experimental results showed decreased glycogen concentration, accumulation of lactate, and net lactate release with ischemia, the onset of glycogen depletion and the switch to lactate efflux were more rapid in the experiments than in the simulations. This study demonstrates the utility of computer models for predicting experimental outcomes in studies of metabolic regulation under physiological and pathological conditions.

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.

Development and experimental validation of a three-dimensional finite element model of the human scapula.

A new modelling approach, using a combination of shell and solid elements, has been adopted to develop a realistic three-dimensional finite element (FE) model of the human scapula. Shell elements were used to represent a part of the compact bone layer (i.e. the outer cortical layer) and the very thin and rather flat part of the scapula--infraspinous fossa and supraspinous fossa respectively. Solid elements were used to model the remaining part of the compact bone and the trabecular bone. The FE model results in proper element shapes without distortion. The geometry, material properties and thickness were taken from quantitative computed tomography (CT) data. A thorough experimental set-up for strain gauge measurement on a fresh bone serves as a reference to assess the accuracy of FE predictions. A fresh cadaveric scapula with 18 strain gauges fixed at various locations and orientations was loaded in a mechanical testing machine and supported at three locations by linkage mechanisms interconnected by ball joints. This new experimental set-up was developed to impose bending and deflection of the scapula in all directions unambiguously, in response to applied loads at various locations. The measured strains (experimental) were compared to numerical (FE) strains, corresponding to several load cases, to validate the proposed FE modelling approach. Linear regression analysis was used to assess the accuracy of the results. The percentage error in the regression slope varies between 9 and 23 per cent. It appears, as a whole, that the two variables (measured and calculated strains) strongly depend on each other with a confidence level of more than 95 per cent. Considering the complicated testing procedure on a fresh sample of scapula, the high correlation coefficients (0.89-0.97), the low standard errors (29-105 micro epsilon) and percentage errors in the regression slope, as compared to other studies, strongly suggest that the strains calculated by the FE model can be used as a valid predictor of the actual measured strain. The model is therefore an alternative to a rigorous three-dimensional model based on solid elements only, which might often be too expensive in terms of computing time.

Functional evaluation of the 10-year outcome after modified Evans repair for chronic ankle instability.

The Evans tenodesis is an operative treatment for chronic ankle instability with good short-term results. The disadvantage of impaired hind foot kinematics and restricted motion has been described, and only few reports of long-term results can be found. No techniques have been used to assess the outcome objectively. We wanted to determine whether a modified Evans procedure led to a satisfactory clinical and functional outcome. Nineteen patients were available at a 10-year follow-up. The clinical examination included a detailed questionnaire and stress radiographs. Foot function was evaluated with plantar pressure distribution measurements during walking and peroneal reaction time measurements elicited on a rapidly tilting platform (recorded with surface electromyography). High subjective patient satisfaction was contrasted with a high rate of residual instability, pain, and swelling. The radiographs showed an increased number of exostoses. The gait analysis revealed reduced peak pressures under the lateral heel and increased values under the longitudinal arch. The reaction times of the peroneal muscles were shorter on the operated side (significant: peroneus longus). The persistent clinical problems as well as the functional changes indicate that the disturbed ankle joint kinematics permanently alter foot function and may subsequently support the development of arthrosis. Therefore, the Evans procedure should only be applied if anatomical reconstruction of the lateral ankle ligaments is not feasible.

Computer-assisted training program for simulation of triage, resuscitation, and evacuation of casualties.

The purpose of this paper is to introduce a multimedia computer software package that has been developed for the Federal Armed Forces of Germany to train military physicians in trauma management. The program presents different groups of casualties with characteristic wounds and multiple injuries on a CD-ROM and provides many clinical options at each decision point. Automatically evaluating the decisions for accuracy, the objective of the program is to train for triage, resuscitation, and evacuation of wounded in combat under pressure of time. The computer-assisted instruction program is inexpensive and allows easily accessible self-instruction as a supplement to formal classroom training. Using this teaching software, it may be possible to teach a standardized emergency case-management algorithm for battlefield trauma. There was a high level of acceptance for this type of instruction. This is encouraging for medical educators involved in producing multimedia packages for teaching emergency medicine.

[Drainage in soft tissue surgery. What is "evidence based"?]. / Drainagen in der Weichteilchirurgie. Was ist "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.

Long-term results of the modified Evans repair for chronic ankle instability.

We treated 19 patients for chronic ankle instability with a modified Evans procedure. All patients were evaluated after an average follow up of 128 months with detailed questionnaire, clinical examination, and stress radiographs. Although the subjective results were reported as 8 excellent, 7 good, and 4 fair, residual pain was reported by 11 patients. There was a significantly increased number of osteophytes in the treated ankle joint. Stress radiographs demonstrated significantly improved stability in the operated ankle joint. Range of motion was significantly reduced in hindfoot inversion. The results showed that the modified Evans procedure achieved sufficient joint stability at the expense of inversion range of motion. This reconstruction method apparently did not prevent the development of arthrosis.

Scaling and suppression of anomalous heating in ion traps.

We measure and characterize anomalous motional heating of an atomic ion confined in the lowest quantum levels of a novel rf ion trap that features moveable electrodes. The scaling of heating with electrode proximity is measured, and when the electrodes are cooled from 300 to 150 K, the heating rate is suppressed by an order of magnitude. This provides direct evidence that anomalous motional heating of trapped ions stems from microscopic noisy potentials on the electrodes that are thermally driven. These observations are relevant to decoherence in quantum information processing schemes based on trapped ions and perhaps other charge-based quantum systems.

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.

[Possibilities of telemedicine within the scope of military medical interventions at foreign posts]. / Möglichkeiten der Telemedizin im Rahmen sanitätsdienstlicher Auslandseinsätze.

Telemedicine is the investigation, monitoring and management of patients and staff using systems which allow ready access to expert advice and patient information, no matter where the patient or the information is located. Telemedicine and teleconsulting have the potential to improve out-of-area military medical care by increasing patient/provider access to specialized medical facilities, services and talent. Similarly, telemedicine can help reduce medical costs by reducing the cost of traveling to and from remotely located medical facilities and services. The Army medical telemedicine effort allows electronic transmission of medical information from remote sites to a designated hub where the transmitted information is available for electronic diagnosis and consultation by health care specialists.

[Femur osteosynthesis in the polytrauma patient--considerations for reasonable surgery time frame from the viewpoint of military service medical treatment]. / Femur-Osteosynthese beim Polytraumatisierten--Uberlegungen zum günstigsten OP-Zeitpunkt aus der Sicht der sanitätsdienstlichen Einsatzmedizin.

OBJECT: What are the concepts of secondary osteosynthesis in polytrauma patients? What are indicators underlying these concepts? Are there consequences for Military Medicine? RESULTS: Conservative stabilization techniques are unsuitable. The intramedullary nail is considered to be large-scaled and technically demanding. It leads to additional stress for the patient (second hit). The following parameters are not suitable: General status, soft-tissue condition, lung fluid, thrombocytes, PNM elastase, cathepsine, lactate, CRP, neopterin, AT III, t-PA-inhibitor, PFI-index, bilirubin. CONCLUSIONS: An objective parameter for the choice of the proper timing of definitive fracture treatment does not exist. In the literature, only few parameters are enumerated. Inconsistent recommendations are hardly discussed. Therefore, from the viewpoint of Military Medicine, we recommend external fixation for primary stabilization. Finally, the systemic inflammatory response has eased off after 5-7 days. Then the definitive operative procedure--intramedullary nailing--should be planned.

[Intracompartmental pressure measurement in in acute compartment syndrome. Results of a survey of indications, measuring technique and critical pressure value]. / Intrakompartimentelle Druckmessung beim akuten Kompartmentsyndrom. Ergebnisse einer Umfrage zu Indikation, Messtechnik und kritischem Druckwert.

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.

[The internet--its uses in traumatology]. / Das Internet--Nutzen für die Traumatologie.

No other words have obtained such meaning in the computer world as the catchwords "Online" and "Internet". The possibilities are innumerable, even in the medical field, and therefore we must consider whether trauma and orthopedic surgeons can also benefit from this new telecommunications medium. As a result of this inquiry, a pilot program has been initiated through an Internet connection at the computer center in the University of Ulm to test and define the possibilities of the Internet in routine clinical applications and for scientific projects. For the surgeon, there is already an abundance of information available: (1) A medical search register consisting of more than 20 million words has been comprised. the source of such searches could be clinics, individuals publications, or even an e-mail answer from a patient's "Help" inquiry. (2) The literature can be researched without difficulty on the data highway. (3) It has become possible to communicate transfer figures, texts, sound and video data within seconds to any connected physician throughout the world over the e-mail system. (4) Included in the many scientific news-letters presented in the Internet ae also several specified for the surgical field. (5) It has also become apparent that a few of the rare German-speaking institutions available on the Internet (for example, the AO Institute in Davos, some university departments and a few research institutes) offer very detailed "Home Pages". In comparison to the American institutions, however, the majority of the German surgical world is not yet connected to the Internet. The Internet offers an enormous information service that is always available and is accessible worldwide. This information can already be used in clinical and scientific applications.

Drainage systems in thyroid surgery: a randomised trial of passive and suction drainage.

OBJECTIVE: To investigate the effectiveness of high-vacuum and passive drainage systems after elective thyroid resection. DESIGN: Prospective randomised clinical study and multicentre postal survey. SETTING: Military hospital, Germany. PATIENTS: 80 patients, treated with passive closed drains (n = 40) or high-vacuum systems (n = 40). INTERVENTIONS: 1. Measuring the amount of blood collected during drainage and the extent of residual haematoma on ultrasonography. 2. Survey in Austria, Germany and Switzerland of annual number of bilateral thyroid resections, type of drainage used, and volume of postoperative drainage. RESULTS: 799 of the 1698 hospitals surveyed replied (47.2%). 785 (98.2%) of the 799 surgeons said that they used drainage systems of whom 766 (97.6%) used high-vacuum systems. In the 40 patients in whom passive closed drainage was used, the median volume drained was 34 ml (range 0-175) compared with 115 ml (40-346) in the high vacuum group (p < 0.01). In the passive drainage group the extent of residual haematoma measured by us was 4.4 ml (range 0-21.7) compared with 5.3 ml (0.6-24.9) in the high vacuum group. CONCLUSIONS: The high-vacuum drainage that is most commonly used in Austria, Germany, and Switzerland results in increased blood loss with no reduction in the extent of residual wound haematoma and offers no additional advantage over passive drainage systems in thyroid surgery.

[The significance of intracompartmental pressure values for the diagnosis of chronic functional compartment syndrome. A meta-analysis of research studies of pressures in anterior M. tibialis during exercise stress]. / Die Bedeutung intrakompartimenteller Druckwerte für die Diagnose des chronisch-funktionellen Kompartmentsyndroms. Eine Metaanalyse von Studien des Druckverlaufs im M. tibialis anterior während einer Ubungsbelastung.

INTRODUCTION: The chronic exertional compartment syndrome of the musculus tibialis anterior is thought to be responsible for a major part of complaints of the lower leg among active sportsmen. There is an important role of tissue pressure measurement in diagnosing chronic anterior compartment syndrome during muscular activity. However, there is a controversial debate about the relevant parameters. METHODS: Metaanalysis of all the 21 studies (1979-1998) measuring intracompartmental pressures during muscular activity. Parameters of analysis: type of exercise, catheter technique, recommendations of diagnostic criteria. RESULTS: Analysis of literature shows that there has been no standardisation concerning the type of muscular exertion (isometrics for 5-10 min, exercise on the treadmill between 3.2 and 12 km/h). In 8 of the 21 studies the results have been attained through the unsuitable Wick-catheter-technique. In the overall view none of the suggested criterions for diagnosis is taken up by other teams. There are considerable variations up to 500% regarding the recommended parameters. CONCLUSIONS: From all studies no uniform recommendation for parameters of diagnostic relevance can be derived. On this background it should be demanded that future research is conducted by a uniform regimen for examination and modern technique of measuring with a high temporal resolution. Under these standardised conditions the investigated parameters of the intracompartmental pressure curve should be reconsidered once more regarding diagnostic predictability by calculations of specifity and sensitivity.

[Reduced muscular oxygen tension and nerve impulse transmission from antishock hose. Reduction of oxygen tension in the tibial muscle and impulse transmission in the peroneal nerve from pneumatic -1 pressure from antishock hose]. / Muskuläre Sauerstoffspannung und nervale Impulsfortleitung bei Einsatz der Antischockhose. Verminderung der Sauerstoffspannung im M. tibialis anterior und Einschränkung der Impulsfortleitung im N. peronaeus profundus infolge pneumatischer Druckeinwirkung durch Antischockhose.

OBJECT OF THE STUDY: The aim of the study was to assess, whether the pneumatic pressure of an antishock-trouser (AST) of 20-40 mm Hg induces a decreased oxygenation of the anterior tibial muscle and attenuates muscular response potential (MRP) of n. peronaeus profundus? METHODS: Among 22 normotensive, healthy volunteers the AST were tested by applying pressure values between 0 and 100 mm Hg and measuring the intracompartmental pressure, the muscular oxygen pressure as well as the MRP by electroneurographic means within a period of 6 hours. RESULTS: The median initial intracompartmental pressure value of the m. tibialis anterior was 12.0 mm Hg (Q25%/Q75%: 8.9/17.3), the muscular oxygen pressure 14.8 mm Hg (Q25%/Q75%: 11.5/22.0). Transmission of the pneumatic AST-leg segment pressure to the muscle: 97.7% (Q25%/Q75%: 89.2/99.8). Already in the low AST pressure field (20-40 mm Hg) a severe hypoxia occurred in one case. A reduction of MRP was noticed at an AST pressure rate of 10 mm Hg. In 5 of 6 cases AST pressure values of 60 mm Hg led to pathological pO2-values within 5-20 minutes. Almost without exception AST-pressure rates < 60 mm Hg resulted in an anoxia of the muscle and loss of the MRP. CONCLUSIONS: We should demand that the AST are only applied with models where the pressure generated within the single segments can be controlled by pressure gauge. The application of the AST seems to be justified for polytraumatised in severe haemorrhagic shock where the risk of a local tissue ischemia with systemical consequences must deliberately be accepted.