Electrocardiogram failure in the operating room - bench testing to prevent bed-side disaster.

Electrocardiogram (ECG) false alarms are common in electrically-hostile peri-operative environments. Newer integrated monitoring, with sophisticated hardware and software, has the potential to minimise artefacts. However, monitoring issues continue to occur, with the potential for critical incidents and unnecessary and harmful interventions. We describe the root cause analysis of a series of apparent ECG flatline asystolic events that appeared in the operating room shortly after the introduction of new intra-operative monitoring systems. Clinical events and biomedical laboratory testing revealed complete loss of ECG signal with increasing resistance. The new ECG systems had incorporated both software and hardware changes to improve the fidelity of signal acquisition and display, but had become much more sensitive to impedance changes. After we alerted the manufacturer, they added software and hardware updates that resulted in resolution of all incidents of ECG loss-of-signal.

[Total knee arthroplasty in the elderly]. / Kniegelenkersatz des älteren Menschen.

BACKGROUND: The number of total knee arthroplasties in elderly patients is increasing in accordance with the demographic shift in the population. OBJECTIVE: Analysis of the special situation in the elderly, conservative treatment options, perioperative risk factors, preoperative preparation, special intraoperative features and outcome. METHODS: Analysis of currently available scientific data and presentation of own scientific study results. RESULTS: Total knee arthroplasty in elderly patients is related to an increased perioperative risk of complications. A thorough interdisciplinary preparation is required to reduce risk factors. Ligament stability of the knee does not correlate with age. The postoperative outcome after total knee arthroplasty in elderly patients is decisively influenced by the preoperative function and psychosocial parameters. CONCLUSION: Total knee arthroplasty in elderly patients is particularly challenging for orthopedic surgeons and requires close interdisciplinary cooperation.

Central X-ray beam correction of radiographic acetabular cup measurement after THA: an experimental study.

PURPOSE: Accurate assessment of cup orientation on postoperative radiographs is essential for evaluating outcome after THA. However, accuracy is impeded by the deviation of the central X-ray beam in relation to the cup and the impossibility of measuring retroversion on standard pelvic radiographs. METHOD: In an experimental trial, we built an artificial cup holder enabling the setting of different angles of anatomical anteversion and inclination. Twelve different cup orientations were investigated by three examiners. After comparing the two methods for radiographic measurement of the cup position developed by Lewinnek and Widmer, we showed how to differentiate between anteversion and retroversion in each cup position by using a second plane. To show the effect of the central beam offset on the cup, we X-rayed a defined cup position using a multidirectional central beam offset. According to Murray's definition of anteversion and inclination, we created a novel corrective procedure to balance measurement errors caused by deviation of the central beam. RESULTS: Measurement of the 12 different cup positions with the Lewinnek's method yielded a mean deviation of [Formula: see text] (95 % CI 1.3-2.3) from the original cup anteversion. The respective deviation with the Widmer/Liaw's method was [Formula: see text] (95 % CI 2.4-4.0). In each case, retroversion could be differentiated from anteversion with a second radiograph. Because of the multidirectional central beam offset ([Formula: see text] cm) from the acetabular cup in the cup holder ([Formula: see text] anteversion and [Formula: see text] inclination), the mean absolute difference for anteversion was [Formula: see text] (range [Formula: see text] to [Formula: see text] and [Formula: see text] (range [Formula: see text] to [Formula: see text] for inclination. The application of our novel mathematical correction of the central beam offset reduced deviation to a mean difference of [Formula: see text] for anteversion and [Formula: see text] for inclination. CONCLUSION: This novel calculation for central beam offset correction enables highly accurate measurement of the cup position.

Digital Planning Software Fails to Reflect Stem Torsion on Plain Radiographs after Total Hip Arthroplasty.

PURPOSE: The purpose of this study was to evaluate the validity of commercially available planning software on plain radiographs after THA compared to CT scans as the gold standard. PATIENTS AND METHODS: In a prospective clinical study, anteroposterior (AP) radiographs and three-dimensional CT scans (3D-CT) were obtained for 121 patients, who underwent minimally invasive, cementless THA with a straight tapered stem, in a lateral decubitus position. For measuring SV, we used digital planning software (TraumaCad 2.0, BrainLAB Feldkirchen, Germany). Two independent raters repeated the analysis after a six-week interval. Radiological measurements were compared with 3D-CT measurements by an independent, blinded external institute. This investigation was approved by the local ethics commission (no. 10 -121- 0263) and is a secondary analysis of a larger project (DRKS00 000 739, German Clinical Trials Register May-02 - 2011). RESULTS: The radiograph measurements showed very high intra- and interrater agreement. The intra-class correlation (ICC) of the intrarater agreement was 0.97 for rater 1 and 0.98 for rater 2. The intrarater reliability was 0.99 using the mean values of both rater measurements. The mean difference between the average radiograph measurement and the 3D-CT-based measurement was 0.41° (SD 11.24°) (range: -33.85°-22.50°; 95 % limits of agreement: -21.63 - 22.45), but there was no correlation found between both methods. CONCLUSION: Measuring stem version with the help of commercially available digital planning software on plain radiographs after THA has high intra- and interrater reliability but clinically inacceptable validity and reliability when compared to 3D-CT scans. KEY POINTS: • Measuring stem torsion after THA on plain radiographs with digital planning software is not valid. Citation Format: • Worlicek M, Weber M, Zeman F et al. Digital Planning Software Fails to Reflect Stem Torsion on Plain Radiographs after Total Hip Arthroplasty. Fortschr Röntgenstr 2016; 188: 763 - 767.

Difference in periprosthetic acetabular bone mineral density: Prior total hip arthroplasty: Osteonecrosis of the femoral head versus primary osteoarthritis.

BACKGROUND: Total hip arthroplasty (THA) could be associated with a higher failure rate in patients after osteonecrosis of the femoral head (ONFH) compared to a patient population with primary osteoarthritis prior THA, especially regarding the acetabular component. One major reason could be the compromised acetabular bone quality. Therefore, we performed a retrospective case matched study to assess: 1) Is there a difference in periprosthetic bone mineral density between patients with an ONFH prior THA and controls? 2) Do patients with an ONFH prior THA have a lower bone mineral density compared to controls? 3) Which region in the periprosthetic bone stock is more likely to present differences in periprosthetic bone mineral density between both groups? HYPOTHESIS: We hypothesized that there is a poorer bone mineral density (BMD) in the periacetabular bone stock in patients with an ONFH prior THA compared to controls receiving a THA due to primary osteoarthritis. PATIENTS AND METHODS: We compared the BMD of 50 patients with ONFH to 50 controls with primary osteoarthritis prior THA using the same implant in mean 5 years after surgery by means of dual energy X-ray absorptiometry (DXA). We analysed 3 acetabular ROIs according to DeLee and Charnley in a modified measurement technique. RESULTS: In ROI 3, representing acetabulum's upper aspect, statistically significant lower BMD values for the ONFH group could be found (P < 0.05). No difference was found for the modified ROIs 1 and 2 (respectively medial and lower acetabulum). DISCUSSION: The results indicate a poorer periacetabular BMD in patients with ONFH prior THA, which might be responsible for premature loosening of the acetabular cup in THA. Due to a lack of literature, further clinical investigations are required to confirm our results. LEVEL OF EVIDENCE: III: retrospective case-control study.

[Bone defect adjusted strategy in revision arthroplasty of the hip : Wich implant in wich situation? Innovations and approved methods]. / Defektadaptierte Rekonstruktionsstrategien in der Hüftrevisionsendoprothetik : Welches Implantat in welcher Situation? Innovationen und Bewährtes.

BACKGROUND: Revision total hip arthroplasty is of rising importance, with 35,000 procedures a year in Germany. OBJECTIVES: Primary stability of the revision implant, reconstruction of the anatomical hip center, reconstruction of bone stock, and permanent secondary integration are the main priorities. METHODS: Current literature and examples from our own experience are presented. RESULTS AND CONCLUSIONS: Novel developments from basic research and industrial partners extend the possibilities for treating affected patients. For an integrated therapy concept in implant selection criteria, such as situation and structure of the defect, combination with any remaining implants, causes of loosening and failure, implant allergy, and patient-specific parameters should be taken into consideration.

[Painful total knee arthroplasty. A treatment algorithm]. / Die schmerzhafte Knieprothese. Ein Behandlungsalgorithmus.

BACKGROUND: Persisting and newly occurring complaints after implantation of a total knee endoprosthesis (TKE) are common problems for orthopaedic surgeons in clinics and private practices. The search for the cause and the diagnostics are often difficult due to the many possible influencing factors. Painful TKE requires patience from the orthopaedic surgeon as well as from the patient. THERAPY MODALITIES: The indications for surgical revision should basically be considered with caution and conservative therapeutic procedures can contribute to a considerable improvement in complaints. The treatment algorithm presented in this article helps to adopt a therapeutic direction and if necessary in assessing the indications for revision or replacement surgery. The algorithm offers the possibility of a systematic classification according to clinical, radiological and laboratory testing aspects and assists in the decision for further procedures depending on the four differential diagnoses of limitations in movement, instability, loosening and infection. CONCLUSION: Revision operations should be performed in specialized centers and should be tailored to the individual patient. A comprehensive knowledge of knee joint biomechanics and experience with the large spectrum of modular and axis-linked revision systems are essential for revision surgeons.

[Principles and new concepts in computer-navigated total hip arthroplasty]. / Grundlagen und neue Konzepte in der computernavigierten Hüftendoprothetik.

Combined component placement of cup and stem is closely correlated to stability, functionality and wear in total hip replacement (THA). Computer-navigated orthopedic surgery offers a reliable control method for a complex three-dimensional situation. Imageless navigation systems without the need of preoperative or intraoperative image acquisition and exposure to radiation have been proven to increase the accuracy of positioning the acetabular component and measure intraoperative leg length and offset changes precisely. A new development in this field is the noninvasive external femoral reference marker array system in conjunction with an imageless measurement technique. The future generation of imageless navigation systems will switch from simple measurement tasks to an integral part of the surgical process in navigated THA. The aim will be to find an optimized complementary component orientation with improved postoperative functionality and optimized range of motion without impingement.

[Minimally invasive surgery in total hip arthroplasty : Surgical technique of the future?]. / Minimalinvasive Operationstechniken in der Hüftgelenktotalendoprothetik : Operationstechniken der Zukunft?

AIM: A selective analysis of the latest literature was carried out including prospective clinical controlled studies on the comparison between minimally invasive total hip arthroplasty (MIS) and the conventional technique. METHODS: An online data base search for controlled study designs within the last 3 years (2009-2011) which compared MIS with standard procedures was performed. Data such as operation time, blood loss, Harris hip score, complications and implant positioning were compared. RESULTS: A total of 11 studies which compared the results of 387 MISs and 264 operations on hips with the standard technique were analyzed. In the majority of the studies reduced levels of creatine kinase and myoglobin as well as reduced intraoperative blood loss were reported. In the early postoperative period up to postoperative week 6 significant advantages in the Harris hip score were reported for the MIS patients. Postoperative complications and implant positioning were comparable in both groups. The operation time was significantly longer in the MIS group for some studies. CONCLUSIONS: Minimally invasive techniques in total hip arthroplasty are nowadays no longer seen as just cosmetically attractive but rather as a real improvement for the clinical outcome. In this respect prospective clinically controlled studies within the last 3 years showed advantages in the early postoperative period.

[Femur first in hip arthroplasty--the concept of combined anteversion]. / Femur first beim Hüftgelenksersatz--Das Konzept der kombinierten Anteversion.

BACKGROUND: The concept of combined anteversion for total hip arthroplasty (THA) proposes a relationship between the cup and stem components that theoretically maximises the postoperative range of motion and minimises the risk for impingement of the joint. Using computer-assisted navigation tools, an anteversion angle of the cup component can be made to be dependent on the antetorsion angle of the stem component (or vice versa). We studied how this functional concept would be different from the traditional cup placement according to the Lewinnek safe zone. PATIENTS AND METHODS: We prospectively reviewed 42 patients (42 hips) who underwent imageless, computer-assisted THA with cementless implants due to osteoarthritis between May and October 2008. Using computer navigation, we determined the cup anteversion with optimised containment and measured femoral stem antetorsion. Our goal was to implant the original implants with a combined anteversion of 37 degrees. RESULTS: Mean cup anteversion was 22.5 degrees, mean combined anteversion was 35.2 degrees. Femoral antetorsion ranged from -13 to 38 degrees (mean: 18 degrees). Mean anteversion of the trial cup with optimised containment was 15.9 degrees and therefore close to the recommendation according to the Lewinnek safe zone. The total postoperative range of motion (flexion, extension, abduction, internal/external rotation) as measured with the navigation system intraoperatively was 209 degrees compared to 94 degrees measured clinically preoperatively. No THA dislocation occurred during the test. CONCLUSION: The combined anteversion concept results in a cup position with more anteversion when compared to the traditional cup placement according to the Lewinnek safe zone. In this context, modern navigation techniques open a new frontier for an optimised component position. Placing the cup and stem in relation to the anteversion for both components allows consideration of the patient-specific biomechanics.

A comparative study of doped and un-doped sol-gel TiO2 and P25 TiO2 (photo)electrodes.

Doped and undoped titanium dioxide films have been deposited on indium tin oxide glass using the sol-gel technique. The percentage of rutile in the prepared TiO2, calcined at 823 K and determined by X-ray diffraction, was 23% compared to 24% of rutile in P25-TiO2. Cerium doped TiO2 showed mainly the anatase phase, as characterised by both X-ray diffraction and Raman spectroscopy. The electrochemical and photoelectrochemical properties of the films were studied by cyclic voltammetry and electrochemical impedance spectroscopy. The (photo)electrochemical characteristics of the different films are reported and discussed.

New insights into the mechanisms of the thermal Fenton reactions occurring using different iron(II)-complexes.

Although the Fenton reagent (a mixture of hydrogen peroxide and an iron(II) salt) has been known for more than a century, the manifold mechanisms occurring during the thermal Fenton reaction are still under discussion. Indeed, this discussion served as a powerful driving force for the steadily increasing insight into the field of inorganic radical and electron transfer chemistry. In this work, an experimental approach towards the elucidation of the first steps taking place in the reaction between several iron(II)-complexes and hydrogen peroxide (H2O2) in water at pH = 3.0 is presented. 2,4-xylidine (2,4-dimethylaniline) reacts differently with reactive intermediates via the addition or hydrogen abstraction by the hydroxyl radical (HO*) or electron transfer reactions to higher valent iron-species, such as a hydrated ferryl-complex (Fe(IV)). The chemical reactivity of the employed iron(II)-complexes with H2O2 differed strongly depending on their ground-state one-electron oxidation potentials. The results are interpreted in accordance with the paradigm originally developed by Goldstein et al. which is based on the evidence obtained from the Marcus theory that outer-sphere electron transfer reactions between metal complexes are not likely to occur because they are too slow. Therefore, most of the "Fenton-reagents" form transient metal complexes, which can be described as [LnFe-H2O2]m+. They form, depending on the reaction conditions, either the hydroxyl radical or higher-valent iron complex species.

Technical development of UV-C- and VUV-photochemically induced oxidative degradation processes.

Technical development work is presented, where the VUV photochemically induced oxidative degradation is used: (i) for analytic purposes, and (ii) for small to medium scale (< 10 m2/d) waste water treatment processes or ultrapure water production. In the first case, small Xe-excimer radiation sources with an integrated reaction space designed for optimal conditions, as far as incident photon flux density, turbulence and concentration of dissolved molecular oxygen are concerned, have been built and tested. Under conditions of exhaustive oxidation and/or mineralization of pollutants in a continuous regime, they may be used for sample pre-treatment modules prior TOC, TOX and electrochemical trace metal analysis. Under conditions of partial oxidation or mineralization, the same lamp/reactor combination may be used for functionalization purposes prior to e.g. GC or HPLC analyses. In the second case, mass transfer limitations between the non-irradiated bulk volume and the irradiated volume are overcome by the electrochemical generation of molecular oxygen within or close to the irradiated volume and by the design of the photochemical part of the reactor.

[Use of solid phase extraction for rapid sample preparation in the determination of food constituents. I. Quinine in beverages]. / Anwendung der Festphasenextraktion zur raschen Probenvorbereitung bei der Bestimmung von Lebensmittelinhaltsstoffen. I. Chinin in Getränken.

A routine method was developed for the determination of quinine in spirits and alcohol-free beverages. Using ion pair chromatography quinine was separated from interfering substances by high-performance liquid chromatography on a RP 18 phase and analysed by UV and fluorescence detection. In contrast to the analysis of alcohol-free beverages, sample preparation was necessary in the study of alcoholic beverages. Solid-phase extraction on phenyl sorbens was found to be a rapid, specific and simple technique.

An experimental in vivo study of the canine internal mammary artery and its response to vasoactive drugs.

The internal mammary artery is clearly the preferred conduit for most patients undergoing coronary artery bypass grafting. However, the hemodynamic responses of this graft to vasoactive agents immediately after bypass have not been documented. We have therefore studied blood flow in the canine internal mammary artery after anastomosis to the left anterior descending artery, and its response to epinephrine, metaraminol, isoproterenol, and calcium chloride. Blood flow in the internal mammary artery clearly paralleled changes in systolic blood pressure with perfusion pressure being of prime importance in maintaining flow in the internal mammary artery. No deleterious effect of systemic vasoconstricting agents was demonstrated. We suggest that the administration of these drugs is safe in patients with internal mammary artery grafts.

Reliability of estimation of pulmonary artery wedge pressures during coronary artery bypass surgery.

The ability to reliably estimate pulmonary artery wedge pressure measurements using the clinical and basic cardiovascular parameters was assessed in fifty-six patients having elective coronary artery bypass surgery. The patients were divided into three groups: Group 1 had normal left ventricular function (22 patients), Group 2 had moderate left ventricular dysfunction (20 patients) and Group 3 had more severe left ventricular dysfunction (14 patients). The percentages of correct pulmonary artery wedge pressure estimations were 55%, 56% and 52% in Groups 1, 2 and 3 respectively. We conclude that pulmonary artery wedge pressure measurements can only be reliably estimated from the clinical situation and basic cardiovascular parameters on about 50% of occasions and that the reliability of the estimation does not vary between groups with different left ventricular performance.

Radial artery cannulation--the influence of method on blood flow after decannulation.

A prospective randomised study of two hundred patients undergoing open-heart surgery was carried out to determine if the method of radial artery cannulation (direct threading or transfixion) had any influence on the incidence of abnormal flow after decannulation. A standard 20-gauge non-tapered teflon-coated cannula was used and the groups were well matched for age, sex, wrist circumference, duration of cannulation and haematoma formation, all of which have been postulated to influence thrombosis rate. We were unable to demonstrate a statistically significant difference between the two methods of cannulation. The overall abnormal flow rate at five days assessed by Doppler ultrasound was low at 5%.