Artificial Intelligence-Based Detection of Pneumonia in Chest Radiographs.

Artificial intelligence is gaining increasing relevance in the field of radiology. This study retrospectively evaluates how a commercially available deep learning algorithm can detect pneumonia in chest radiographs (CR) in emergency departments. The chest radiographs of 948 patients with dyspnea between 3 February and 8 May 2020, as well as 15 October and 15 December 2020, were used. A deep learning algorithm was used to identify opacifications associated with pneumonia, and the performance was evaluated by using ROC analysis, sensitivity, specificity, PPV and NPV. Two radiologists assessed all enrolled images for pulmonal infection patterns as the reference standard. If consolidations or opacifications were present, the radiologists classified the pulmonal findings regarding a possible COVID-19 infection because of the ongoing pandemic. The AUROC value of the deep learning algorithm reached 0.923 when detecting pneumonia in chest radiographs with a sensitivity of 95.4%, specificity of 66.0%, PPV of 80.2% and NPV of 90.8%. The detection of COVID-19 pneumonia in CR by radiologists was achieved with a sensitivity of 50.6% and a specificity of 73%. The deep learning algorithm proved to be an excellent tool for detecting pneumonia in chest radiographs. Thus, the assessment of suspicious chest radiographs can be purposefully supported, shortening the turnaround time for reporting relevant findings and aiding early triage.

[Health literacy and nonurgent emergency department visits]. / Gesundheitskompetenz und Notfallverhalten.

Background: The number of patients with nonurgent health conditions using emergency departments (ED) is growing steadily. It is unclear however whether this is associated with limited health literacy of patients. Objectives: This study aims to explore the health literacy of patients with nonurgent conditions in an ED, compare it with the health literacy of the general population and identify relationships between health literacy and patients' views on emergency care. Materials and methods: A total of 448 patients with nonurgent conditions participated in a cross-sectional survey in the ED of a German university hospital. Results: The study shows that health literacy of nonurgent emergency patients is significantly lower than the health literacy of the German population. Patients with lower levels of health literacy perceive higher treatment urgency, are significantly less informed about treatment options other than the ED and are more likely to visit the ED or the outpatient walk-in practice for a second opinion after having seen their general practitioner. Conclusion: The results indicate a need for action to improve health literacy in Germany. In particular, current structural changes in emergency care in Germany have to be considered.

Performance of antigen testing for diagnosis of COVID-19: a direct comparison of a lateral flow device to nucleic acid amplification based tests.

OBJECTIVES: The gold standard for diagnosing an infection with SARS-CoV-2 is detection of viral RNA by nucleic acid amplification techniques. Test capacities, however, are limited. Therefore, numerous easy-to-use rapid antigen tests based on lateral flow technology have been developed. Manufacturer-reported performance data seem convincing, but real-world data are missing. METHODS: We retrospectively analysed all prospectively collected antigen tests results performed between 23.06.2020 and 26.11.2020, generated by non-laboratory personnel at the point-of-care from oro- or nasopharyngeal swab samples at the University Hospital Augsburg and compared them to concomitantly (within 24 h.) generated results from molecular tests. RESULTS: For a total of 3630 antigen tests, 3110 NAAT results were available. Overall, sensitivity, specificity, NPV and PPV of antigen testing were 59.4%, 99.0%, 98.7% and 64.8%, respectively. Sensitivity and PPV were lower in asymptomatic patients (47.6% and 44.4%, respectively) and only slightly higher in patients with clinical symptoms (66.7% and 85.0%, respectively). Some samples with very low Ct-values (minimum Ct 13) were not detected by antigen testing. 31 false positive results occurred. ROC curve analysis showed that reducing the COI cut-off from 1, as suggested by the manufacturer, to 0.9 is optimal, albeit with an AUC of only 0.66. CONCLUSION: In real life, performance of lateral-flow-based antigen tests are well below the manufacturer's specifications, irrespective of patient's symptoms. Their use for detection of individual patients infected with SARS-CoV2 should be discouraged. This does not preclude their usefulness in large-scale screening programs to reduce transmission events on a population-wide scale.

The voice of COVID-19: Acoustic correlates of infection in sustained vowels.

COVID-19 is a global health crisis that has been affecting our daily lives throughout the past year. The symptomatology of COVID-19 is heterogeneous with a severity continuum. Many symptoms are related to pathological changes in the vocal system, leading to the assumption that COVID-19 may also affect voice production. For the first time, the present study investigates voice acoustic correlates of a COVID-19 infection based on a comprehensive acoustic parameter set. We compare 88 acoustic features extracted from recordings of the vowels /i:/, /e:/, /u:/, /o:/, and /a:/ produced by 11 symptomatic COVID-19 positive and 11 COVID-19 negative German-speaking participants. We employ the Mann-Whitney U test and calculate effect sizes to identify features with prominent group differences. The mean voiced segment length and the number of voiced segments per second yield the most important differences across all vowels indicating discontinuities in the pulmonic airstream during phonation in COVID-19 positive participants. Group differences in front vowels are additionally reflected in fundamental frequency variation and the harmonics-to-noise ratio, group differences in back vowels in statistics of the Mel-frequency cepstral coefficients and the spectral slope. Our findings represent an important proof-of-concept contribution for a potential voice-based identification of individuals infected with COVID-19.

Typical Imaging Patterns in COVID-19 Infections of the Lung on Plain Chest Radiographs to Aid Early Triage.

PURPOSE: To evaluate imaging patterns of a COVID-19 infection of the lungs on chest radiographs and their value in discriminating this infection from other viral pneumonias. MATERIALS AND METHODS: All 321 patients who presented with respiratory impairment suspicious for COVID-19 infection between February 3 and May 8, 2020 and who received a chest radiograph were included in this analysis. Imaging findings were classified as typical for COVID-19 (bilateral, peripheral opacifications/consolidations), non-typical (findings consistent with lobar pneumonia), indeterminate (all other distribution patterns of opacifications/consolidations), or none (no opacifications/consolidations). The sensitivity, specificity, as well as positive and negative predictive value for the diagnostic value of the category "typical" were determined. Chi² test was used to compare the pattern distribution between the different types of pneumonia. RESULTS: Imaging patterns defined as typical for COVID-19 infections were documented in 35/111 (31.5 %) patients with confirmed COVID-19 infection but only in 4/210 (2 %) patients with any other kind of pneumonia, resulting in a sensitivity of 31.5 %, a specificity of 98.1 %, and a positive and negative predictive value of 89.7 % or 73 %, respectively. The sensitivity could be increased to 45.9 % when defining also unilateral, peripheral opacifications/consolidations with no relevant pathology contralaterally as consistent with a COVID-19 infection, while the specificity decreases slightly to 93.3 %. The pattern distribution between COVID-19 patients and those with other types of pneumonia differed significantly (p < 0.0001). CONCLUSION: Although the moderate sensitivity does not allow the meaningful use of chest radiographs as part of primary screening, the specific pattern of findings in a relevant proportion of those affected should be communicated quickly as additional information and trigger appropriate protective measures. KEY POINTS: · COVID-19 infections show specific X-ray image patterns in 1/3 of patients.. · Bilateral, peripheral opacities and/or consolidations are typical imaging patterns.. · Unilateral, peripheral opacities and/or consolidations should also raise suspicion of COVID-19 infection.. CITATION FORMAT: · Kasper J, Decker J, Wiesenreiter K et al. Typical Imaging Patterns in COVID-19 Infections of the Lung on Plain Chest Radiographs to Aid Early Triage. Fortschr Röntgenstr 2021; 193: 1189 - 1196.

Multitasking behaviors and provider outcomes in emergency department physicians: two consecutive, observational and multi-source studies.

BACKGROUND: Multitasking is a key skill for emergency department (ED) providers. Yet, potentially beneficial or debilitating effects for provider functioning and cognition are underexplored. We therefore aimed to investigate the role of multitasking for ED physicians' work stress and situation awareness (SA). METHODS: Two consecutive, multi-source studies utilizing standardized expert observations in combination with physicians' self-reports on stress and SA were set out in an academic ED. To control for ED workload, measures of patient acuity, patient counts, and ED staff on duty were included. Regression analyses estimated associations between observed proportion of time spent in multitasking with matched ED physicians' reports on stress (study 1) and SA (study 2). RESULTS: ED physicians engaged between 18.7% (study 1) and 13.0% (study 2) of their worktime in multitasking. Self-reported as well as expert-observed multitasking were significantly associated. This confirms the internal validity of our observational approach. After controlling for ED workload, we found that physicians who engaged more frequently in multitasking perceived higher work stress (Beta = .02, 95%CI .001-.03; p = .01). In study 2, ED physicians with more frequent multitasking behaviors reported higher SA (B = .08, 95%CI .02-.14; p = .009). CONCLUSIONS: Multitasking is often unavoidable in ED care. Our findings suggest that ED physicians' multitasking increases stress experiences, yet, may facilitate professional's experiences of situation awareness. Our results warrant further investigation into potentially ambivalent effects of ED providers' multitasking in effectively sharing time between competing demands while maintaining performance and safety.

Physicians' and nurses' work time allocation and workflow interruptions in emergency departments: a comparative time-motion study across two countries.

BACKGROUND: Globally, emergency department (ED) work is fast-paced and subject to interruptions, placing high coordination and communication demands on staff. Our study aimed to compare ED staffs' work time allocation and interruption rates across professional roles and two national settings. METHODS: We conducted a time-motion study with standardised expert observations of ED physicians and nurses in Germany and the USA. Observers coded ED staffs' activities and workflow interruptions. General and generalised linear models were used to examine differences in activities and interruption rates between countries and ED professions. RESULTS: 28 observations were conducted in the USA and 30 in Germany. Overall, the largest portion of time spent by ED staff in both settings was in documentation (22.0%). Physicians spent more time in verbal interaction with patients (9.9% vs 5.2% in nurses; p=0.006), in documentation (29.4% vs 15.6%; p<0.001) and other professional activities (13.0% vs 4.8%; p=0.002). Nurses allocated significantly more time to therapeutic (22.3% vs 6.0% in physicians; p<0.001) and organisational activities (20.4% vs 9.5%; p<0.001). Overall mean interruption rate per hour was 10.16 (US ED: 8.15, German ED: 12.04; p<0.001). American physicians and German nurses were most often disrupted by colleagues of the same profession (country: B=-.27, p=0.027; profession: B=0.35, p=0.006). German ED staff were interrupted more often by patients (B=-.78, p=0.001) and other sources (B=-.76, p<0.001) than American ED staff. DISCUSSION: Our findings corroborate that professional roles largely determine time allocation to specific activities. However, interruption rates indicate differences between countries, suggesting the need for context-specific solutions to work stressors.

Workflow disruptions and provider situation awareness in acute care: An observational study with emergency department physicians and nurses.

BACKGROUND: The fast-paced and rapidly changing environment of an Emergency Department (ED) requires providers to have a high level of situation awareness (SA). However, acute clinical care also encompasses a multitude of interruption-laden work processes that might degrade SA. It is therefore important to understand how frequent interruptions affect ED provider cognition in general and SA in particular. OBJECTIVE: We aimed to examine how sources and contents of provider workflow interruptions influence situation awareness of ED physicians and nurses. METHODS: This prospective, multi-method study combined standardized observations, self-reports of ED providers, and ED administrative data of staffing and patient load. Expert observers identified ED providers' workflow interruptions during 90min observation sessions. Afterwards, each provider reported perceived disruptiveness and situation awareness. Controlling for patient load, patient acuity and staffing, we conducted regression analyses to explore prospective associations between interruptions and provider outcomes. RESULTS: During 74 observation sessions of overall 110h and 40min, we observed 1205 workflow interruptions (mean rate: 10.9 interruptions/hour). Provider situation awareness was fairly high (M = 7.10; scale 0-10) with no difference between ED physicians and nurses. After controlling for ED workload data, we observed that high rates of interruptions were associated with lower levels of situation awareness (ß = -0.27). Further analyses revealed that particularly interruptions by telephone/beeper, technical malfunctions as well as interruptive communication related to completed cases were correlated to low SA. DISCUSSION: This study in a naturalistic ED setting shows that ED physicians and nurses continuously cope with disruptions and interruptions. Our findings reveal that highly interruptive workflow environments impede providers' situation awareness. Moreover, it sheds light on specific sources and contents of interruptions that influence providers' SA in acute care. CONCLUSION: Frequent workflow interruptions can degrade ED providers' situation awareness. A deeper understanding of how avoidable and unavoidable interruptions affect provider cognitions with particular focus on social and technology-related disruptions is required. Further emphasis should be placed on the effective application of work re-design in this context to foster safe and efficient patient care.

Effects of work conditions on provider mental well-being and quality of care: a mixed-methods intervention study in the emergency department.

BACKGROUND: Emergency departments (EDs) are highly dynamic and stressful care environments that affect provider and patient outcomes. Yet, effective interventions are missing. This study evaluated prospective effects of a multi-professional organizational-level intervention on changes in ED providers' work conditions and well-being (primary outcomes) and patient-perceived quality of ED care (secondary outcome). METHODS: A before and after study including an interrupted time-series (ITS) design over 1 year was established in the multidisciplinary ED of a tertiary referral hospital in Southern Germany. Our mixed-methods approach included standardized provider surveys, expert work observations, patient surveys, and register data. Stakeholder interviews were conducted for qualitative process evaluation. ITS data was available for 20 days pre- and post-intervention (Dec15/Jan16; Dec16/Jan17). The intervention comprised ten multi-professional meetings in which ED physicians and nurses developed solutions to work stressors in a systematic moderated process. Most solutions were consecutively implemented. Changes in study outcomes were assessed with paired t-tests and segmented regression analyses controlling for daily ED workload. RESULTS: One hundred forty-nine surveys were returned at baseline and follow-up (response at baseline: 76 out of 170; follow-up: 73 out of 157). Forty-one ED providers participated in both waves. One hundred sixty expert work observations comprising 240 observation hours were conducted with 156 subsequent work stress reports. One thousand four hundred eighteen ED patients were surveyed. Considering primary outcomes, respondents reported more job control and less overtime hours at follow-up. Social support, job satisfaction, and depersonalization deteriorated while respondents' turnover intentions and inter-professional interruptions increased. Considering the secondary outcome, patient reports indicated improvements in ED organization and waiting times. Interviews revealed facilitators (e.g., comprehensive approach, employee participation) and barriers (e.g., understaffing, organizational constraints) for intervention implementation. CONCLUSIONS: To the best of our knowledge, this is the first study to report prospective effects of an ED work system intervention on provider well-being and patient-perceived quality of ED care. We found inconsistent results with partial improvements in work conditions and patient perceptions of care. However, aspects of provider mental well-being deteriorated. Given the lack of organizational-level intervention research in EDs, our findings provide valuable insights into the feasibility and effects of participatory interventions in this highly dynamic hospital setting.

Provider interruptions and patient perceptions of care: an observational study in the emergency department.

BACKGROUND: Interruptions are endemic in healthcare work environments. Yet, they can have positive effects in some instances and negative in others, with their net effect on quality of care still poorly understood. We aimed to distinguish beneficial and detrimental forms of interruptions of emergency department (ED) providers using patients' perceptions of ED care as a quality measure. METHODS: An observational design was established. The study setting was an interdisciplinary ED of an academic tertiary referral hospital. Frequencies of interruption sources and contents were identified in systematic expert observations of ED physicians and nurses. Concurrently, patients rated overall quality of care, ED organisation, patient information and waiting times using a standardised survey. Associations were assessed with hierarchical linear models controlling for daily ED workload. Regression results were adjusted for multiple testing. Additionally, analyses were computed for ED physicians and nurses, separately. RESULTS: On 40 days, 160 expert observation sessions were conducted. 1418 patients were surveyed. Frequent interruptions initiated by patients were associated with higher overall quality of care and ED organisation. Interruptions relating to coordination activities were associated with improved ratings of ED waiting times. However, interruptions containing information on previous cases were associated with inferior ratings of ED organisation. Specifically for nurses, overall interruptions were associated with superior patient reports of waiting time. CONCLUSIONS: Provider interruptions were differentially associated with patient perceptions of care. Whereas coordination-related and patient-initiated interruptions were beneficial to patient-perceived efficiency of ED operations, interruptions due to case-irrelevant communication were related to inferior patient ratings of ED organisation. The design of resilient healthcare systems requires a thorough consideration of beneficial and harmful effects of interruptions on providers' workflows and patient safety.

Workflow interruptions and stress atwork: a mixed-methods study among physicians and nurses of a multidisciplinary emergency department.

OBJECTIVES: Dealing with multiple workflow interruptions is a major challenge in emergency department (ED) work. This study aimed to establish a taxonomy of workflow interruptions that takes into account the content and purpose of interruptive communication. It further aimed to identify associations of workflow interruptions with ED professionals' work stress. DESIGN: Combined data from expert observation sessions and concomitant self-evaluations of ED providers. SETTING: ED of an academic community hospital in Germany. PARTICIPANTS: Multidisciplinary sample of ED physicians and nurses. 77 matched observation sessions of interruptions and self-evaluations of work stress were obtained on 20 randomly selected days. OUTCOME MEASURES: ED professionals' stress evaluations were based on standardised measures. ED workload data on patient load, patient acuity and staffing were included as control variables in regression analyses. RESULTS: Overall mean rate was 7.51 interruptions/hour. Interruptions were most frequently caused by ED colleagues of another profession (27.1%; mean interruptions/hour rate: 2.04), by ED colleagues of the same profession (24.1%; 1.81) and by telephone/beeper (21%; 1.57). Concerning the contents of interruption events, interruptions most frequently occurred referring to a parallel case under care (30.3%, 2.07), concerning the current case (19.1%; 1.28), or related to coordination activities (18.2%, 1.24). Regression analyses revealed that interruptive communication related to parallel cases significantly increased ED providers' stress levels (ß=0.24, P=0.03). This association remained significant after controlling for ED workload. DISCUSSION: Interruptions that refer to parallel cases under care were associated with increased stress among ED physicians and nurses. Our approach to distinguish between sources and contents of interruptions contributes to an improved understanding of potential benefits and risks of workflow interruptions in ED work environments. Despite some limitations, our findings add to future research on the implications of interruptions for effective and safe patient care and work in complex and dynamic care environments.

Development of the competency-based medical curriculum for the new Augsburg University Medical School.

Aim: With the resolution from April 28, 2014, the Bavarian state government in Germany decided to found a new medical school at Augsburg University, thereby requiring the development of a competency-based medical curriculum. Methods: Two interdisciplinary groups developed a spiral curriculum (following Harden) employing the model of Thumser-Dauth & Öchsner. The curriculum focuses on specifically defined competencies: medical expertise, independent scientific reasoning, argumentation and scholarship, as well as communication skills. Results: The spiral curriculum was developed as a hybrid curriculum. Its modular structure incorporates the mandatory subjects required by the German regulations for medical licensure (Approbationsordnung) into organ- and system-centered blocks which are integrated both horizontally and vertically. Basic preclinical sciences are covered in the blocks "Movement," "Balance" and "Contact." The clinical sciences are organized according to six pillars (conservative medicine, surgical medicine, men's-women's-children's medicine, the senses, the nervous system and the mind, and general medicine) which students revisit three times each over the course of the program. A longitudinal clinical course incorporates interdisciplinary education. A particular focus is on scientific education encompassing a longitudinal course in the sciences (including interdisciplinary classes with other university departments), block practicums, and two scientific projects. Conclusion: It is not only the degree of integration und intensity of the Augsburg University undergraduate medical degree program, but also its targeted advancement of academic, social and communication skills that have not yet been realized to such an extent elsewhere in Germany. On July 8, 2016, the German Council of Science and Humanities unanimously gave this concept a positive evaluation. Future research will examine and evaluate the Augsburg medical curriculum and the impact of the new medical school on the hospital and university in Augsburg.

Hemodynamic efficacy of sequential hemoclip application using the Olympus HX-110/610 reloadable clipping device in spurting bleedings.

BACKGROUND: Hemoclip application in GI-hemorrhage has proven to be effective. Clinical experience shows that multiple clips are frequently necessary. In 2005, an easily reloadable clip-applicator was introduced. We evaluated the hemodynamic efficacy of this new device. MATERIAL/METHODS: We prospectively compared the new clipping device (Olympus HX 110/610) in a validated experimental setting using the compactEASIE®-simulator for GI bleeding. The artificial blood circulation system in the simulator was connected to a pressure transducer. Four investigators of different endoscopic experience (1000-6000 endoscopies) treated 12 bleeding sources each, with up to 6 clips for each bleeding location. Pressures were recorded to objectify the additive effects of sequential clip application on the reduction in vessel diameter. The intervention was abandoned if a maximum measurable pressure of 300 mmHg was achieved. RESULTS: Hemoclip application led to a significant increase of peak pressure (91±100 mmHg, p<0.001) and mean pressure (95±99 mmHg, p<0.001), representing a significant reduction in vessel diameter. Pooled data showed a significant stepwise increase in mean and maximum system pressure, resulting in reduction of vessel diameter up to the fifth hemoclip. On average, 5 clips (range 1-6) were used. More experienced endoscopists achieved a higher increase in mean pressure (167 and 118 mmHg vs 72 and 23 mmHg, p<0.05). Mean reloading time was 39 seconds (19-49 sec). CONCLUSIONS: Sequential application of multiple hemoclips led to an increasing effect, comparable to the results of previous clinical trials. The number of hemoclips applied correlated inversely, but not significantly, with the endoscopist´s experience. Expensive single-use clips appear dispensable in view of the short reloading time.

Genetic polymorphisms of manganese-superoxide dismutase and glutathione-S-transferase in chronic alcoholic pancreatitis.

Chronic alcohol consumption is a major risk factor for the development of chronic pancreatitis. However, chronic pancreatitis occurs only in a minority of heavy drinkers. This variability may be due to yet unidentified genetic factors. Several enzymes involved in the degradation of reactive oxidants and xenobiotics, such as glutathione-S-transferase P1 (GSTP1) and manganese-superoxide dismutase (MnSOD) reveal functional polymorphisms that affect the antioxidative capacity and may therefore modulate the development of chronic pancreatitis and long-term complications like endocrine and exocrine pancreatic insufficiency. Two functional polymorphisms of the MnSOD and the GSTP1 gene were assessed by polymerase chain reaction and restriction fragment length polymorphism in 165 patients with chronic alcoholic pancreatitis, 140 alcoholics without evidence of pancreatic disease and 160 healthy control subjects. The distribution of GSTP1 and MnSOD genotypes were in Hardy-Weinberg equilibrium in the total cohort. Genotype and allele frequencies for both genes were not statistically different between the three groups. Although genotype MnSOD Ala/Val was seemingly associated with the presence of exocrine pancreatic insufficiency, this subgroup was too small and the association statistically underpowered. None of the tested genotypes affected the development of endocrine pancreatic insufficiency. Polymorphisms of MnSOD and GSTP1 are not associated with chronic alcoholic pancreatitis. The present data emphasize the need for stringently designed candidate gene association studies with well-characterized cases and controls and sufficient statistical power to exclude chance observations.

Interventional endoscopic therapy in chronic pancreatitis including temporary stenting: a definitive treatment?

OBJECTIVE: In the past 15 years there have been tremendous advances in endoscopic management of chronic pancreatitis (CP). However, the value of endoscopic pancreatic stenting is still debatable. MATERIAL AND METHODS: In 98 patients suffering from symptomatic CP (84 M, 14 F, 49+/-12, age range 23-83 years) endotherapy including temporary stenting of the pancreatic duct was performed. After final stent removal, indicating the primary end-point of endotherapy, 96 patients were followed for 35+/-28 (8 days-111) months. All data were assessed retrospectively. RESULTS: As well as other endoscopic procedures, a total of 358 prostheses were inserted in the pancreatic duct and left in place for 3+/-1 (1 day-11) months. Total stent treatment time was 10+/-10 (6 days-49) months. At 46+/-27 (4-111) months after limited endotherapy, 57 patients had no need for secondary intervention, two-thirds were even without further pain sensations. In 22 patients, surgical treatment and in 17 patients further endoscopic therapy became necessary, which was significantly correlated with continued alcohol consumption. CONCLUSIONS: Temporary stent placement as a part of interventional endoscopic therapy in CP shows a high rate of technical and long-term clinical success, with no need for secondary treatment in a remarkable number of patients. Continued cessation of alcohol consumption supports the treatment benefit significantly.

Pancreatic endoprostheses in chronic pancreatitis: criteria to predict stent occlusion.

BACKGROUND: Good clinical results of main pancreatic duct (MPD) stent placement in chronic pancreatitis (CP) are clouded by early stent occlusion. The aim of this study was to increase knowledge about stent occlusion and its effects on clinical symptoms, and to define criteria that enable the prediction of clogging. METHODS: A total of 100 pancreatic endoprostheses of 47 patients (32 men, 15 women; mean age, 53 years; standard deviation, 9 years) with CP were bench tested by simulating the pathophysiologically increased MPD pressure. The main study parameter was the reduction of water flow through clogged stents in comparison with native endoprostheses of identical type, length, and diameter. Major stent occlusion was defined as flow reduction by > or = 75%. The association between time to stent occlusion and stent- or patient-related variables was evaluated. RESULTS: Occlusion took place in nearly all endoprostheses (97%). No significant association of occlusion with clinical or blood parameters was found. Multifactorial analysis proved 4 risk factors for major stent occlusion: (A) stent diameter > 8.5F, (B) stent length > 8 cm, (C) female gender, (D) exocrine pancreatic insufficiency that required regular oral enzyme supplementation. According to the relative risk, these factors were given the following scores: A, 3 points; B to D, 2 points. Stents in patients with a score sum > 5 showed a significantly higher risk of major stent occlusion within 90 days. CONCLUSIONS: Stent clogging in CP seems to be an inevitable phenomenon. Because clinical and laboratory data do not reliably indicate clogging, stent removal or exchange should be performed in high-risk patients (score sum > 5) within 3 months.

Composition of clogging material in pancreatic endoprostheses.

BACKGROUND: Endoscopic management of chronic pancreatitis (CP), especially pancreatic stent placement, has made tremendous advances. However, good clinical results are hampered by rapid occlusion. The objective of this study was to understand mechanisms and materials that cause stent occlusion. METHODS: The clogging material of 50 lyophilized pancreatic endoprostheses (length 8.5 cm, range 5-14 cm, diameter 7-11F) from patients with CP was completely removed and weighed. Protein solubilization was achieved at pH 8.0 by using sodium dodecyl sulfate (SDS) and 2-mercaptoethanol in the presence of proteasome inhibitors. Proteins were separated by using a SDS-polyacrylamide gel electrophoresis. Protein identification was performed by the Western blot technique, as well as by mass spectrometry. Insoluble components were examined by polarized light microscopy and after staining (periodic acid-Schiff [PAS]). RESULTS: Clogging material was found in 49 prostheses, mainly at the duodenal flap (80%). More than a third of the prostheses contained visible calcium carbonate calculi. Light microscopy and PAS staining showed plant debris (80%), crystals (73.5%), and mucopolysaccharides (100%). The dry weight of clogging material (18 +/- 13 mg, range 3-72 mg) correlated significantly with the stent diameter ( p = 0.029) but not with any other stent- or patient-related criteria. Albumin, its degradation products, and lithostathine were identified as the main proteinaceous components. CONCLUSIONS: Almost all pancreatic stents had clogging material, predominantly located at the duodenal flap, which contained plant material, mucopolysaccharides, and crystals, as well as visible calcium carbonate calculi. Albumin and lithostathine may play an important role in the development of stent occlusion.

Multifactorial risk analysis of bone marrow histiocytic hyperplasia with hemophagocytosis in critically ill medical patients--a postmortem clinicopathologic analysis.

OBJECTIVE: Systematic studies of the prevalence and risk factors of histiocytic hyperplasia with hemophagocytosis (HHH) in critically ill patients are lacking. The aim of our study was a) to determine the frequency and intensity of HHH in the bone marrow of patients who died on the medical intensive care unit; b) to analyze morphologic bone marrow changes; and c) to identify possible risk factors and their interactions in the pathogenesis of HHH. DESIGN: A retrospective observational analysis of clinical data and autopsy findings including histologic and immunohistological analysis of bone marrow to characterize cellularity, siderosis, hemophagocytosis, and T-cell infiltrates. SETTING: The medical intensive care unit of a university hospital. PATIENTS: Patients were 107 consecutive patients who died and underwent autopsy. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: HHH was identified in 69 of the 107 patients (64.5%). Moderate to severe HHH was present in 35 of the 107 bone marrows. Univariate risk factor analysis showed that HHH was associated with various intrinsic and extrinsic factors. However, multivariate analysis identified the intensity of therapeutic interventions--represented by the Therapeutic Intervention Scoring System--as the only positive, and cardiovascular disease as the only significant negative, predictor of HHH (p <.05). Routine laboratory tests were of no value in predicting the presence of HHH. The intensity of HHH correlated significantly with siderosis and T-cell infiltrates (p <.05) but not with bone marrow cellularity. CONCLUSIONS: HHH is common in medical intensive care unit nonsurvivors. Treatment intensity and a noncardiovascular cause of death are predictors of HHH. Sepsis and blood transfusion may have a synergistic effect on the triggering of HHH. HHH in bone marrow is associated with enhanced T-cell infiltrates, suggesting that T cells may play an important role in its mediation.