Evaluation of daily environmental cleaning and disinfection practices in veterans affairs acute and long-term care facilities: A mixed methods study

OBJECTIVES

To describe daily environmental cleaning and disinfection practices and their associations with cleaning rates while exploring contextual factors experienced by healthcare workers involved in the cleaning process.

METHODS

A convergent mixed methods approach using quantitative observations (ie, direct observation of environmental service staff performing environmental cleaning using a standardized observation form) and qualitative interviews (ie, semistructured interviews of key healthcare workers) across 3 Veterans Affairs acute and long-term care facilities.

RESULTS

Between December 2018 and May 2019 a total of sixty-two room observations (N = 3602 surfaces) were conducted. The average observed surface cleaning rate during daily cleaning in patient rooms was 33.6% for all environmental surfaces and 60.0% for high-touch surfaces (HTS). Higher cleaning rates were observed with bathroom surfaces (Odds Ratio OR = 3.23), HTSs (OR = 1.57), and reusable medical equipment (RME) (OR = 1.40). Lower cleaning rates were observed when cleaning semiprivate rooms (OR = 0.71) and rooms in AC (OR = 0.56). In analysis stratified by patient presence (ie, present, or absent) in the room during cleaning, patient absence was associated with higher cleaning rates for HTSs (OR = 1.71). In addition, the odds that bathroom surfaces being cleaned more frequently than bedroom surfaces decreased (OR = 1.97) as well as the odds that private rooms being cleaned more frequently than semi-private rooms also decreased (OR = 0.26; 0.07-0.93). Between January and June 2019 eighteen qualitative interviews were conducted and found key themes (ie, patient presence and semiprivate rooms) as potential barriers to cleaning; this supports findings from the quantitative analysis.

CONCLUSION

Overall observed rates of daily cleaning of environmental surfaces in both acute and long-term care was low. Standardized environmental cleaning practices to address known barriers, specifically cleaning practices when patients are present in rooms and semi-private rooms are needed to achieve improvements in cleaning rates.

Quantitative microbial risk assessment of human norovirus infection in environmental service workers due to healthcare-associated fomites

BACKGROUND

Healthcare-associated norovirus outbreaks place a large burden on healthcare staff. Environmental service workers (ESWs), however, remain understudied despite high contact with potentially contaminated surfaces. Understanding the magnitude of the risk of norovirus infection in healthcare ESWs can protect workers and improve infection control.

AIM

This study simulated the risk of norovirus infection for unprotected ESWs after a single fomite contact, assuming no disinfection or protective equipment, in norovirus-positive patient rooms. In addition, the risk of secondary surface transmission from norovirus-exposed ESWs was simulated.

METHODS

A quantitative microbial risk assessment employing two-dimensional Monte Carlo simulation with parameters extracted from the literature was used to estimate norovirus infection from multiple fomite contact scenarios defined by: norovirus source (patient vomit/diarrhoea), location (bathroom/patient room) and target outcome (ESW/secondary illness).

FINDINGS

Unprotected ESWs have a maximum estimated risk of norovirus infection of 33% (1:3) for a single fomite contact in a room where a norovirus-positive patient had a diarrhoeal event. Patient vomit events lead to fomite contact risk estimates that are four orders of magnitude lower than those for diarrhoeal events. The estimated risk of secondary illness from touching a common surface is as high as 25% (1:4) after single fomite exposure following a diarrhoeal event.

CONCLUSIONS

A single fomite contact may lead to sizable risk of norovirus infection in ESWs if personal protective equipment and disinfection are not used appropriately. ESWs can also transfer virus to secondary surfaces, initiating further infections. Interventions are needed to reduce fomite transfer of norovirus, and protect patients and staff from nosocomial infections.

Quasi-Static Tensile Properties of Unalloyed Copper Produced by Electron Beam Powder Bed Fusion Additive Manufacturing

Mechanical properties of powder bed fusion processed unalloyed copper are reported majorly in the as-fabricated condition, and the effect of post-processes, common to additive manufacturing, is not well documented. In this study, mechanical properties of unalloyed copper processed by electron beam powder bed fusion are characterized via room temperature quasi-static uniaxial tensile test and Vickers microhardness. Tensile samples were extracted both perpendicular and parallel to the build direction and assigned to three different conditions: as-fabricated, hot isostatic pressing (HIP), and vacuum annealing. In the as-fabricated condition, the highest UTS and lowest elongation were obtained in the samples oriented perpendicular to the build direction. These were observed to have clear trends between sample orientation caused primarily by the interdependencies between the epitaxial columnar grain morphology and dislocation movement during the tensile test. Texture was insignificant in the as-fabricated condition, and its effect on the mechanical properties was outweighed by the orientation anisotropy. The fractographs revealed a ductile mode of failure with varying dimple sizes where more shallow and finely spaced dimples were observed in the samples oriented perpendicular to the build direction. EDS maps reveal that grain boundary oxides coalesce and grow in HIP and vacuum-annealed specimens which are seen inside the ductile dimples and contribute to their increased ductility. Overall, for the post-process parameters chosen in this study, HIP was observed to slightly increase the sample’s density while vacuum annealing reduced the oxygen content in the specimens.

Glycation and Serum Albumin Infiltration Contribute to the Structural Degeneration of Bioprosthetic Heart Valves

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Two novel and interacting mechanisms contributing to BHV SVD are reported: glycation and serum albumin infiltration.

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Glycation product formation and serum albumin deposition were observed in 45 clinical BHV explanted due to SVD as well as BHV tissue subcutaneously implanted in rats.

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In vitro exposure to glycation and serum albumin elicited collagen network misalignment similar to that seen in clinical and rat explant BHV tissue.

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Glycation was sufficient to impair BHV hydrodynamic function in ISO-5840-compliant pulse duplication testing and concomitant serum albumin infiltration exacerbated these effects.

Valvular heart diseases are associated with significant cardiovascular morbidity and mortality, and often require surgical and/or percutaneous repair or replacement. Valve replacement is limited to mechanical and biological prostheses, the latter of which circumvent the need for lifelong anticoagulation but are subject to structural valve degeneration (SVD) and failure. Although calcification is heavily studied, noncalcific SVD, which represent roughly 30% of BHV failures, is relatively underinvestigated. This original work establishes 2 novel and interacting mechanisms—glycation and serum albumin incorporation—that occur in clinical valves and are sufficient to induce hallmarks of structural degeneration as well as functional deterioration.

Epidemiology of invasive pneumococcal disease and vaccine provision in a tertiary referral center

Invasive pneumococcal disease (IPD) has an all-cause mortality of 5-35 % in the developed world. Pneumococcal vaccination is recommended for at-risk groups, including those infected with human immunodeficiency virus (HIV) and those over 65 years of age. However, adherence to vaccination guidelines is low. We reviewed all cases of IPD in our tertiary referral hospital from 2006 to 2010. IPD was defined as the isolation of Streptococcus pneumoniae from a normally sterile site with a compatible clinical syndrome. Demographics, risk factors, susceptibilities, pneumococcal serotype, mortality, and vaccination status for each patient were analyzed. There were 127 IPD episodes in 122 patients. The overall case fatality rate was 21.2 %. Seventy-two percent of the patients had two or more risk factors that should have prompted pneumococcal vaccination. However, the overall pneumococcal vaccination provision was only 9 %: 64.6 % of all typed isolates were contained in the pneumococcal polysaccharides vaccine 23 (PPV23), 48.8 % in the 7-valent pneumococcal conjugate vaccine (PCV7), and 60.1 % in PCV13. All isolates were fully sensitive to penicillin and cefotaxime. Recurrent IPD was seen in 11 % of the HIV-infected patients, highlighting a particular at-risk group. IPD has a high mortality rate. There is low vaccine provision in our study, although most IPD patients had risk factors that should have prompted vaccination. HIV-positive people are particularly at risk; vaccinating those with persisting CD4 counts less than 200 cells/mm(3) and the use of "prime-boost" strategies may decrease incidence in the future. Newer models of care such as a dedicated vaccine clinic as described in this study may help increase vaccine provision and uptake.

Hydrogen peroxide is a common signal for darkness- and ABA-induced stomatal closure in Pisum sativum

The requirement for hydrogen peroxide (H₂O₂) generation and action during stomatal closure induced by darkness and abscisic acid (ABA) was investigated in pea (Pisum sativum L.). Stomatal closure induced by darkness or ABA was inhibited by the H₂O₂-scavenging enzyme catalase or the antioxidant N-acetyl cysteine (NAC), or by diphenylene iodonium (DPI), an inhibitor of the H₂O₂-generating enzyme NADPH oxidase. Exogenous H₂O₂ induced stomatal closure in a dose- and time-dependent manner, and H₂O₂ was also required for ABA-inhibition of stomatal opening in the light. H₂O₂ accumulation in guard cells was increased by darkness or ABA, as assessed with the fluorescent dye dichlorodihydrofluorescein diacetate (H₂-DCFDA) and confocal microscopy. Such increases were inhibited by catalase, NAC or DPI, consistent with the effects of these compounds on stomatal apertures. Employing polymerase chain reaction (PCR) with degenerate oligonucleotide primers, several NADPH oxidase homologues were identified from pea genomic DNA that had substantial identity to the Arabidopsis thaliana (L.) Heynh. rboh (respiratory burst oxidase homologue) genes. Furthermore, an antibody raised against the tomato rboh identified immunoreactive proteins in epidermal, mesophyll and guard cells.

[Computed tomography in the diagnosis of inflammatory bowel disease -- methodology of MSCT and clinical results]

PURPOSE

This paper discusses the diagnostic yield of multislice computed tomography (MSCT) in inflammatory bowel disease.

METHODS

Contrast media are administered intraluminally (colon, small intestine) and intravenously (triple contrast CT). Filling of small bowel is achieved by means of jejunal tube ("Sellink CT") or via the oral route. Pharmacological relaxation of the intestine decreases motion artifact. Intraluminal contrast media consist of either hyperdense, "positive" or hypodense, "negative" liquids.

RESULTS

Thin-slice MSCT of the entire abdomen allows high-quality post processing (MPR, thin-slice MIP). Due to superior distension, Sellink CT improves estimation of stenosis or changes in thickness and contrast of bowel wall. Positive contrast is superior in the detection and preoperative localization of abscess, fistula or conglomerate tumour, because it accurately differentiates between intra- and extraluminal structures.However, negative contrast facilitates quantitative evaluation of bowel wall thickening or enhancement and demonstrates gastrointestinal bleeding.

CONCLUSION

MSCT of the small intestine is superior to conventional enteroclysis, especially in the diagnosis of mesenterial or other extraintestinal disease. As a side effect, the colon is assessed in the same examination. Radiation dose is less in MSCT (7.8-13.3 mSv) than in conventional fluoroscopy (13.99+/-7.57 mSv). MSCT can be performed as an alternative or adjunct to colonoscopy, if endoscopic access is restricted. It is already the imaging modality of choice in acute diverticulitis.

[Radiological interventions in inflammatory bowel disease]

INTRODUCTION

Abscesses, fistulas,hemorrhages and stenoses are common complications of inflammatory bowel diseases. This study provides an overview on various methods of radiological intervention and the clinical usefulness of these methods is analyzed.

METHODS

The success rate of percutaneous abscess drainage (PAD), embolisation of hemorrhages and dilatation of bowel stenoses is reviewed and current literature is addressed. Success rate is defined in terms of cure rate and need for subsequent surgery.

RESULTS

After PAD, surgery can be avoided during the observation period in about 50% of patients with abscesses due to Crohn's disease and diverticulitis. Preoperative PAD reduces the degree of invasiveness and thus the risk of surgery. Abscess recurrence is found with the same frequency following surgery or PAD. Bowel dilatation can be performed both with radiological and with endoscopic guidance.Embolisation of GI-hemorrhage is technically feasible, but the indication should be limited to strictly selected cases.

CONCLUSIONS

In treating abscesses and fistulas associated with Crohn's disease and diverticulitis, PAD is a valuable treatment option. Embolisation or dilatation are restricted to rare cares.

[Structured radiologic diagnosis in polytrauma]

PURPOSE

Development of a concept for structured diagnostic imaging in patients with multiple trauma.

MATERIAL AND METHODS

Evaluation of data from a prospective trial with over 2400 documented patients with multiple trauma. All diagnostic and therapeutic steps, primary and secondary death and the 90 days lethality were documented. Structured diagnostic imaging of multiple injured patients requires the integration of an experienced radiologist in an interdisciplinary trauma team consisting of anesthesia, radiology and trauma surgery. Radiology itself deserves standardized concepts for equipment, personnel and logistics to perform diagnostic imaging for a 24-h-coverage with constant quality.

RESULTS

This paper describes criteria for initiation of a shock room or emergency room treatment, strategies for documentation and interdisciplinary algorithms for the early clinical care coordinating diagnostic imaging and therapeutic procedures following standardized guidelines. Diagnostic imaging consists of basic diagnosis, radiological ABC-rule, radiological follow-up and structured organ diagnosis using CT. Radiological trauma scoring allows improved quality control of diagnosis and therapy of multiple injured patients.

CONCLUSION

Structured diagnostic imaging of multiple injured patients leads to a standardization of diagnosis and therapy and ensures constant process quality.

[Focal secondary malignant liver lesions: MnDPDP-enhanced MRT at 0.2 tesla vs. helical CT-arterioportography]

PURPOSE

Prospective evaluation of the efficacy of MnDPDP- enhanced MRI using an open low-field scanner for the detection of focal malignant liver lesions in comparison with helical CT- arterioportography (CT AP).

MATERIAL AND METHODS

As part of a phase III study, 27 consecutive patients we enrolled for comparison, with seven patients later eliminated for failing the inclusion criteria. Native and MnDPDP-enhanced MRI of the liver at a field-strength of 0.2 Tesla (Siemens Magnetom Open) and DSA with helical CT AP (Siemens Somatom Plus 4) were performed within one week. The lesions were compared collectively and after categorization by size: (a) < 1 cm, (b) 1 - 2 cm, and (c) > 2 cm. For statistical evaluation, the sign test with a significance level of p < 0.05 was used.

RESULTS

CT AP depicted 114 lesions, whereas native MRI detected 62 and MnDPDP-enhanced MRI revealed 69 lesions. Significant differences were shown for collective comparison and for selective comparison of category (b), and of categories (a) and (b) combined. No significant differences were found between native and contrast-enhanced MRI.

CONCLUSION

MnDPDP should be reserved for high-field strengths since low field strengths cannot be expected to confirm or exclude malignant liver lesions reliably.

[The value of magnetic resonance cholangiography for the expedient diagnosis of choledocholithiasis]

INTRODUCTION

Management of symptomatic cholecystolithiasis is vitally influenced by dilated biliary tract and choledocholithiasis. The objectives of this prospective pilot study were to evaluate the diagnostic value of preoperative magnetic resonance cholangiography (MRC) compared to diagnostic endoscopic retrograde cholangiography (ERC) and to establish an efficient algorithm for diagnostics and treatment of choledocholithiasis.

METHODS

All consecutive patients with cholecystolithiasis and dilated biliary tract proven by sonography as well as elevated liver function tests were enrolled within 12 months. Patients without evidence of bile duct calculi underwent preoperative MRC, whereas patients with choledocholithiasis immediate ERC.

RESULTS

58 patients (30 male, 28 female) with a median age of 59.4 years underwent preoperative MRC. In 18 patients (10 male, 8 female; median age 63.5 years) with evidence of choledocholithiasis we subsequently performed ERC and papillotomy. Bile duct stones were detected and removed after papillotomy in 10 patients, whereas calculi could not be found anymore in 8 patients. The remaining 40 patients without calculi evident on MRC were transferred to magnetic resonance tomography and ERC in case of suspected malignancy or to cholecystectomy and intraoperative cholangiography (IOC), which could definitely exclude choledocholithiasis. In comparison to ERC respectively IOC, MRC was able to detect bile duct stones with a sensitivity of 100% and a specificity of 83.3%.

CONCLUSIONS

Non-invasive MRC seems to replace diagnostic ERC concerning the presence of choledocholithiasis in case of cholecystolithiasis and dilated biliary tract with a high sensitivity. The preoperative ERC with stone extraction is still the therapy of choice in case of radiologically confirmed choledocholithiasis.

[Studies on image quality, high contrast resolution and dose for the axial skeleton and limbs with a new, dedicated CT system (ISO-C-3 D)]

PURPOSE

Evaluation of 3D-CT imaging of the axial skeleton and different joints of the lower and upper extremities with a new dedicated CT system (ISO-C-3D) based on a mobile isocentric C-arm image amplifier.

MATERIAL AND METHODS

27 cadaveric specimes of different joints of the lower and upper extremities and of the spinal column were examined with 3D-CT imaging (ISO-C-3D). All images were evaluated by 3 radiologists for image quality using a semiquantitative score (score value 1: poor quality; score value 4: excellent quality). In addition, dose measurements and measurements of high contrast resolution were performed in comparison to conventional and low-dose spiral CT using a high contrast phantom (Catphan, Phantom Laboratories).

RESULTS

Adequate image quality (mean score values 3 - 4) could be achieved with an applied dose comparable to low-dose CT in smaller joints such as wrist, elbow, ankle and knee. A remarkably inferior image quality resulted in imaging of the hip, lumbar and thoracic spine (mean score values 2 - 3) in spite of almost doubling the dose (dose increased by 85 percent). The image quality of shoulder examinations was insufficient (mean score value 1). Phantom studies showed a high-contrast resolution comparable to helical CT in the xy-axis (9 lp/cm).

CONCLUSION

Preliminary results show, that image quality of C-arm-based CT-imaging (ISO-C-3D) seems to be adequate in smaller joints. ISO-C-3D images of the hip and axial skeleton show a decreased image quality, which does not seem to be sufficient for diagnosing subtle fractures.

[Detection of tibial condylar fractures using 3D imaging with a mobile image amplifier (Siemens ISO-C-3D): Comparison with plain films and spiral CT]

PURPOSE

To analyze a prototype mobile C-arm 3D image amplifier in the detection and classification of experimental tibial condylar fractures with multiplanar reconstructions (MPR).

METHOD

Human knee specimens (n = 22) with tibial condylar fractures were examined with a prototype C-arm (ISO-C-3D, Siemens AG), plain films (CR) and spiral CT (CT). The motorized C-arm provides fluoroscopic images during a 190 degrees orbital rotation computing a 119 mm data cube. From these 3D data sets MP reconstructions were obtained. All images were evaluated by four independent readers for the detection and assessment of fracture lines. All fractures were classified according to the Müller AO classification. To confirm the results, the specimens were finally surgically dissected.

RESULTS

97 % of the tibial condylar fractures were easily seen and correctly classified according to the Müller AO classification on MP reconstruction of the ISO-C-3D. There is no significant difference between ISO-C and CT in detection and correct classification of fractures, but ISO-CD-3D is significant by better than CR.

CONCLUSION

The evaluation of fractures with the ISO-C is better than with plain films alone and comparable to CT scans. The three-dimensional reconstruction of the ISO-C can provide important information which cannot be obtained from plain films. The ISO-C-3D may be useful in planning operative reconstructions and evaluating surgical results in orthopaedic surgery of the limbs.

[Introduction of a new mobile C-arm/CT combination equipment (ISO-C-3D). Initial results of 3-D sectional imaging]

Preclinical evaluation of a new mobile C-arm image amplifier with an option for three-dimensional computed tomography (CT) imaging (prototype Iso-C3D) with respect to high-contrast resolution and possible clinical applications. Cadaveric specimens (n = 30) of different joints of the lower and upper extremities and specimens of the spinal column were examined with the Iso-C3D and evaluated for image quality. In addition, using a high-contrast phantom (Catphan, Phantom Laboratory, Salem, N.Y., USA) and a fracture model of the femoral bone, measurements of high-contrast resolution were performed in comparison to spiral CT. With the exception of the shoulder, all joint regions including the entire spinal column could be examined. Adequate image quality could be achieved in smaller joints such as the wrist, elbow, ankle, and knee, whereas a remarkably decreased image quality was found when imaging the hip as well as the lumbar and thoracic spine. Images of the phantom study and high-contrast fracture model showed a high-contrast resolution comparable to helical CT (9 Lp/cm in xy-axis). In smaller joints, the image quality of the mobile C-arm CT imaging system (Iso-C3D) is comparable to that of helical CT. Image quality in examinations of the hip and lumbar and thoracic spine seems to be sufficient for intraoperative control studies of osteosynthesis. Problems still occur in shoulder examinations.

[3-D imaging with a mobile surgical image enhancement equipment (ISO-C-3D). Initial examples of fracture diagnosis of peripheral joints in comparison with spiral CT and conventional radiography]

To analyze a prototype mobile C-arm image amplifier (Iso-C3D) in the evaluation of different joint fractures of the upper and lower limbs using multiplanar reconstruction (MPR). Different cadaver joint specimens (n = 14) were examined with a prototype (Iso-C3D, Siemens AG, Erlangen, Germany), plain radiographs (CR), and spiral computed tomography (CT). The motorized C-arm provides fluoroscopic images during a 190 degrees orbital rotation computing a 119-mm data cube. These three-dimensional data sets yielded MPR images, which were evaluated by two readers for the detection and extent of fracture lines. Initial data show that fractures were easily depicted and correctly classified on MPR images with the Iso-C3D and that there was no difference between the Iso-C and CT in the detection of fractures. The preliminary results suggest a remarkably good detection of joint fractures with the Iso-C3D. Studies in an adequate number of patients are required to elucidate whether these promising results can also be obtained in a clinical setting.

Noninvasive diagnosis of emphysema. Aerosol morphometry and aerosol bolus dispersion in comparison to HRCT

Aerosol-derived airway morphometry (ADAM) and aerosol bolus dispersion (ABD) test are altered in patients with emphysema. We examined the diagnostic power of these aerosol methods in comparison with the noninvasive "gold-standard" HRCT in 50 consecutive patients with various lung diseases. The severity of airflow limitation was mild to moderate in the group of patients without emphysema and moderate to severe in the group of patients with HRCT-confirmed emphysema (FEV(1), 78 +/- 23% pred versus 53 +/- 33% pred; p < 0. 001). Among all lung function parameters under consideration ADAM showed the highest sensitivity and specificity for separating patients with emphysema from those without emphysema (area under the operating characteristics curve: p(ROC), 0.92), followed by ABD (p(ROC), 0.90), a marker for ventilation inhomogeneities. In patients with HRCT-confirmed macroscopic emphysema, peripheral air-space dimensions (EAD) at a relative volumetric lung depth V(pr) of 0.20 measured by ADAM were 155% larger, and bolus dispersion (ABD) at a lung depth of V(p) 600 ml was 53% larger than those observed in patients with other lung diseases (EAD = 0.84 +/- 0.53 mm versus 0.33 +/- 0.10 mm, p < 0.0001; ABD = 706 +/- 154 cm(3) versus 462 +/- 109 cm(3); p < 0.0001). EAD showed a significant correlation with the HRCT visual score (r = 0.78, p = 0.01). ABD showed weak significant correlations with all HRCT parameters under consideration (visual score, pixel density, mean lung density) (r = 0.45 to 0.66; p < 0.05). ADAM and ABD are powerful tools for the noninvasive diagnosis of macroscopic emphysema.

[Temporary balloon occlusion as therapy of uncontrollable arterial hemorrhage in multiple trauma patients]

PURPOSE

Presentation of temporary balloon occlusion as an interventional radiological method for managing hemorrhage in multiply injured patients with uncontrollable loss of blood.

METHOD

Temporary, non-selective arterial occlusion by introduction of a balloon catheter contralaterally to the source of bleeding has been performed since 1992 on 7 patients with multiple injuries, hemorrhagic shock requiring reanimation, and angiographic demonstration of an arterial hemorrhage in the supply region of the internal iliac artery with complex pelvic fracture. In each case a PTA balloon catheter was introduced transfemorally, non-selectively positioned proximal to the bleeding source, and left in place for 24-48 h under manometric control. Control angiographies were performed prior to catheter removal.

RESULTS

The bleeding was stopped immediately in all 7 patients. The hemodynamic stability made transport and thus further surgical management and/or a short-term treatment in the intensive-care station possible. Control angiographies confirmed that the bleeding had stopped in all patients.

CONCLUSIONS

We recommend temporary balloon occlusion as a rapid and effective method for the management of bleeding in otherwise uncontrollable traumatic hemorrhages in the supply region of the internal iliac artery.

Indications, management, and complications of temporary inferior vena cava filters

PURPOSE

We describe the results of a preliminary prospective study using different recently developed temporary and retrievable inferior vena cava (IVC) filters.

METHODS

Fifty temporary IVC filters (Günther, Günther Tulip, Anthéor) were inserted in 47 patients when the required period of protection against pulmonary embolism (PE) was estimated to be less than 2 weeks. The indications were documented deep vein thrombosis (DVT) and temporary contraindications for anticoagulation, a high risk for PE, and PE despite DVT prophylaxis.

RESULTS

Filters were removed 1-12 days after placement and nine (18%) had captured thrombi. Complications were one PE during and after removal of a filter, two minor filter migrations, and one IVC thrombosis.

CONCLUSION

Temporary filters are effective in trapping clots and protecting against PE, and the complication rate does not exceed that of permanent filters. They are an alternative when protection from PE is required temporarily, and should be considered in patients with a normal life expectancy.

Radiation dose and image quality in spiral computed tomography: multicentre evaluation at six institutions

The purpose of this study was to evaluate the correlation of radiation dose with image quality in spiral CT. Seven clinical protocols were measured in six different radiological departments provided with four different types of high specification spiral CT scanners. Central and surface absorbed doses were measured in acrylic. The practical CT dose index (PCTDI) was calculated for seven clinical examination protocols and one standardized protocol using identical parameters on four different spiral CT scanners with a dedicated ionization chamber inserted into PMMA phantoms. For low contrast measurements, a cylindrical three-dimensional (3D) phantom (different sized spheres of defined contrast) was used. Image noise was measured with a cylindrical water phantom and high contrast resolution with a Perspex hole phantom. Image quality phantoms were scanned using the parameters of the clinical protocols. Images were randomized, blinded and read by six radiologists (one from each institution). PCTDI values for four different scanners varied up to a factor between 1.5 (centre) and 2.2 (surface) for the standardized protocol. A greater degree of variation was observed for seven clinical examination protocols of the six radiological departments. For example, PCTDI varied up to a factor between 1.7 (cerebrum protocol) and 8.3 (abdomen paediatric protocol). Low contrast resolution correlates closely with dose. An improvement in detection from 8 mm to 4 mm sized spheres needs approximately a ten-fold increase in dose. Noise shows a moderate correlation with PCTDI. High contrast resolution of clinical protocols is independent of PCTDI within a certain range. Differences in modern CT scanner technology seem to be of less importance for radiation exposure than selection of protocol parameters in different radiological institutes. Future discussion on guidelines regarding optimal (patient adapted) tube current for clinical protocols is desirable.

[Dosimetry in conventional and spiral CT in 8 spiral CT scanners of the latest generation]

PURPOSE

Measurement of scanner-dependent differences in PCTDI for conventional and spiral CT and evaluation of PCTDI/100 mAs in eight spiral CT scanners of the latest generation.

METHODS

Central PCTDI was evaluated in a PMMA phantom for different scan lengths of conventional and spiral CT in four scanners. Central and peripheral PCTDI/100 mAs, average dose and the quotient between peripheral and central PCTDI/100 mAs were measured with a dedicated 10 cm ionisation chamber positioned within a PMMA phantom using the parameters of a standardised liver protocol and a high-resolution inner ear protocol for eight spiral CT scanners.

RESULTS

Depending on scanner type and scan length PCTDI for the spiral mode is in a range between 11.3% higher and 4.3% lower than that for the conventional mode. PCTDI/100 mAs varies considerably between different CT scanners. For the standardised liver protocol PCTDI/100 mAs varies up to a factor of 2, for the inner ear protocol up to a factor of 4.

CONCLUSION

Even in comparable modern CT scanners there are considerable protocol and scanner-dependent differences in PCTDI/100 mAs. The values for his own scanner should be known to each CT user so that he can develop a dose-optimised, patient and problem-orientated examination strategy.

[Stress on the wrist joint in semilunar bone necrosis--a morphologic study in vivo]

The distribution of subchondral mineralization of the distal articular surface of the radius was examined by CT osteoabsorptiometry in both wrists of twelve patients showing different stages of Kienböck's disease. The pattern of density distribution had already been demonstrated in previous studies to be an adequate parameter for assessing axial loading across the wrist joint in the patients. Contrary to the anticipated presence of predominant stress in the lunate compartment, some patients showed identical stress in the compartment of the scaphoid, and the balanced loading of both compartments, as before. Even when in early stages of the disease the lunate type of mineralization appeared more often, it was still not possible to demonstrate general excessive stress on the lunate. We have therefore concluded that the main stress in the scaphoid compartment might be a secondary effect, which is to be regarded as the expression of the advancing destruction of the lunate and consequent loss of load transmission through this compartment. This hypothesis is also supported by the fact that, in progressive stages of Kienböck's disease, the density maximum in the fovea lunata, generally present in healthy people, is absent. Furthermore, in patients with necrosis of the lunate, the total mineralization in terms of the maximal density values in the distal joint surface of the radius is in the majority of cases less than in the normal subject. In two cases, even the density maximum was absent from the fovea lunata of the contralateral wrist joint, without there being any clinical signs suggesting a possible lunate necrosis on this side. We interpret these pathological changes in the unaffected wrist joint as a further indication that we are dealing with a congenital predisposition which affects both wrist joints.

Antioxidant nutrient supplementation reduces the susceptibility of low density lipoprotein to oxidation in patients with coronary artery disease

OBJECTIVE

This study sought to determine the effect of antioxidant supplementation on the susceptibility of low density lipoprotein (LDL) to oxidation in patients with established cardiovascular disease (CVD).

BACKGROUND

Data are inconsistent regarding the role of antioxidant nutrients in the prevention of CVD.

METHODS

The study design was a 12-week, double-blind, placebo-controlled clinical trial. Patients with CVD (n = 45) were randomized to 1) placebo control; 2) 400 IU of vitamin E, 500 mg of vitamin C, 12 mg of beta-carotene (mid-dose); or 3) 800 IU of vitamin E, 1,000 mg of vitamin C, 24 mg of beta-carotene (high dose) daily. Reduced susceptibility of LDL to oxidation was estimated by an increase in lag phase (minutes). Baseline and 6- and 12-week measurements of lipoproteins and lag phase were obtained. Plasma levels of antioxidants were measured at baseline and 12 weeks.

RESULTS

Concentrations of alpha-tocopherol, vitamin C and beta-carotene significantly increased in the mid- and high dose groups during the trial. Lag phase significantly increased from baseline (190.1 +/- 63.8 min [mean +/- SD]) to 12 weeks (391.1 +/- 153.0 min) in the high dose group (p < 0.01). A nonsignificant increase in lag phase in the mid-dose group was observed during the same time interval. A dose response was found for mean percent change from baseline to 12 weeks for lag phase for the placebo, mid- and high dose groups (p = 0.004 for trend).

CONCLUSIONS

A high dose combination of antioxidant nutrients reduces the susceptibility of LDL to oxidation in patients with CVD and may be useful in secondary prevention.

Direct comparison of contact areas, contact stress and subchondral mineralization in human hip joint specimens

X-ray densitometric and CT osteoabsorptiometric findings suggest that in the human hip subchondral mineralization patterns change from bicentric to monocentric as a function of age. It has been hypothesized that these changes indicate an alteration in the geometric configuration of the joint from incongruous to congruous, possibly associated with the onset of osteoarthrosis. The purpose of this study was therefore to directly compare contact rates, contact stress and subchondral mineralization in the hip joint. Twelve specimens without cartilage lesions (ages 34-86 years) were investigated. Simulating the mid-stance phase, the contact areas were determined by polyether casting and the contact stress with Fuji film. The distribution of subchondral mineralization was assessed non-invasively with CT osteoabsorptiometry. At small loads the load-bearing areas were located at the periphery of the lunate surface. In some joints they were found in the acetabular roof and expanded, with higher loads, to the center of the lunate surface and the anterior and posterior horns. In other joints, the contact areas were recorded at lower loads in the anterior and posterior horns, and only at higher forces they merged in the acetabular roof. The maximal contact stress ranged from 8 t 9 MPa at 300% body weight. Maxima of subchondral mineralization were recorded in the acetabular roof, in the anterior and posterior horns, or in all three locations. There was no clear correlation between the distribution of contact and pressure, and the pattern of subchondral bone density. Incongruity is shown to strongly affect the distribution of contact and pressure in the human hip joint. However, the pattern of subchondral mineralization cannot be readily explained in terms of the contact areas and contact stress during mid-stance. Incongruity may give rise to tensile stresses in the subchondral bone, and the construction of the pelvis as a whole may play an important role in subchondral bone loss loads and adaptation.

Altered patterns of subchondral bone mineralization in Kienböck's disease

The pattern of subchondral bone density, which is supposed to reflect the long-term distribution of stress, was investigated in both wrist joints of nine healthy young subjects and seven patients suffering from Kienböck's disease by means of CT osteoabsorptiometry. Two density maxima were found on the distal articular surface of the radius in the healthy subjects, corresponding to the position of the scaphoid and the lunate. Our relative quantitative results showed three different physiological types of stress indicated by the predominantly monocentric density maxima either on the scaphoid or the lunate surface of the radius and the symmetrical distribution of the mineralization. In Kienböck's disease no type of mineralization predominated. In the progressive stages the lunate density maximum was absent. The overall mineralization was generally less than in controls. Changes in the pattern of mineralization were also found on the contralateral side.

Changes in resting energy expenditure and body composition in anorexia nervosa patients during refeeding

Accurate prediction of the energy level necessary to promote weight restoration in patients with anorexia nervosa would be clinically useful. Resting energy expenditure (REE), respiratory quotient, and body composition were measured in 10 nonmedicated women with anorexia nervosa during a vigorous refeeding protocol. REE was measured three times per week by open-circuit indirect calorimetry after an overnight fast. Subjects ranged in age from 19 to 38 years and weighed 39.9 +/- 4.3 kg (mean +/- standard deviation) at admission. The refeeding protocol was as follows: phase 1, 1,200 kcal/day for 1 week (baseline); phase 2, an increase of 300 kcal/day for 1 week; phase 3, 3,600 kcal/day until target weight was reached; phase 4, 1,800 to 2,800 kcal/day (stabilization). REE was 30.0 +/- 6.4, 33.5 +/- 6.7, 37.3 +/- 6.6 and 34.5 +/- 4.4 kcal/kg body weight during phases 1, 2, 3, and 4, respectively. The Harris-Benedict equation overestimated phase 1 24-hour REE by a mean of 14% and underestimated REE in phases 2, 3, and 4 by a mean of 8%, 24%, and 23%, respectively. Skinfold measurements revealed percent body fat to be 12 +/- 4% at admission and 19 +/- 5% at discharge, with a mean of 48% of the weight gained during refeeding attributable to increased body fat. These findings indicate that refeeding in anorexia nervosa is associated with increased REE, which cannot be explained by increased body mass, and that caloric requirements for weight restoration in patients with anorexia nervosa are best determined by monitoring individual response.

[Intraperitoneal fetal small intestine transplantation in allogeneic rat strains]

We demonstrated the possibility of a successful transplant of foetal rat small intestine into the peritoneal cavity of adult rats. Several combinations of rat strains with defined genetic differences were chosen. On the whole, in more than 66 percent of the performed transplantations a successful adequate growth of the transplants was noted. Oral application of Cyclosporin A (20 mg/kg/d) as immunosuppressive to prevent allograft rejection was necessary only in the combination across major genetic barriers. The preoperative insertion of a 7-0 non-absorbable thread into the lumen of the transplant helped to develop a tubular segment of small intestine which can be anastomosed to the intestinal continuity of the host in a second stage operation.