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Biomedical subjects

Knut Kröger

Publications and source records attributed to Knut Kröger.

At least 19 recordsLinked to original sources
PubMed2006

Reliability and validity of pressure ulcer diagnosis and grading: an image-based survey.

BACKGROUND: The reliability and validity of pressure ulcer diagnosis and grading are major methodological issues in studies and reports on pressure ulcer frequency. OBJECTIVES: The aim of the study was to estimate the reliability and validity of pressure ulcer diagnosis and grading within the interdisciplinary pressure ulcer project of the University Clinics of Essen, Germany. DESIGN: Fifty images of wounds from the foot/heel region and 50 images of wounds from the buttock/hip region were classified using a 4-grade scale. A gold standard was established by consensus of two senior physicians. SETTINGS: The images were assessed PC-based, independently by each rater. PARTICIPANTS: Five nursing experts and two physicians participated. METHODS: Mean simple Kappa and per cent agreement were calculated to assess reliability and validity. RESULTS: Mean simple Kappa values showed a moderate interrater agreement for grading and a fair interrater agreement for diagnosis. The percentage of agreements was highest for pressure ulcer diagnosis in the buttock/hip region with 90.5% and lowest for pressure ulcer grading in the buttock/hip region with 63.5%. No differences could be found between nurses and physicians. CONCLUSIONS: The differentiation between pressure ulcers and other skin lesions is rather difficult. It is important to assign the lower grade when the available information does not definitely support the higher grade. The level of agreement found was intermediate in the range of published results. A substantial level of agreement should be obtainable through further standardisation and training. Future studies should control for dependency in the assessment situation and dispense with the category "uncertain".

Buttocks↗
PubMed2006

Coronary atherosclerosis and cardiovascular risk in masters male marathon runners. Rationale and design of the "marathon study".

BACKGROUND: Regular physical exercise is recommended to reduce cardiovascular mortality. And yet, atherosclerosis is the main cause of exercise-associated death in persons beyond age 35. The need for risk stratification in marathon runners is under discussion. The predictive value of modern imaging- and non-imaging-based markers of risk that can be used for risk stratification in masters endurance athletes still deserves exploration. METHODS: Male runners > 50 years who have completed at least five marathon races during the preceding 3 years and do not suffer from coronary artery disease, angina nor diabetes mellitus are studied to assess the predictive value of established and modern imaging- based and biochemical cardiovascular risk factors. Laboratory parameters including clinical chemistry, hematology and hormone measurements are determined. Lifestyle-related risk factors, psychosocial and socioeconomic variables are explored using standardized questionnaires. Coronary, carotid, femoral and aortic atherosclerosis is measured using electronbeam computed tomography and ultrasound. In addition, a resting ECG, a bicycle stress test and heart rate variability are performed. Myocardial morphology and function are assessed using echocardiography and magnetic resonance imaging. Participants are invited to compete in a marathon race to quantify the association of coronary atherosclerosis with marathon-related changes of cardiac troponin levels and the extent of marathon-induced inflammation. At the cellular level, the effect on the amount of circulating progenitor cells (EPCs) is determined by FACS analysis. Changes in laboratory parameters and hormone levels are also studied. Annual long-term follow-up including hospital records and death certificates is performed. Data are compared with those from a general unselected cohort from the Heinz Nixdorf Recall Study. CONCLUSION: This study should contribute to cardiovascular risk assessment in the growing number of masters marathon runners with a focus on assessing the predictive value of modern imaging techniques and biochemical markers for comprehensive risk stratification.

Adult↗
PubMed2006

Prevalence of peripheral arterial disease - results of the Heinz Nixdorf recall study.

BACKGROUND: This report presents population-based estimates of the prevalence of peripheral arterial disease (PAD), chronic critical limb ischemia (CLI), and Moenckeberg's medial calcinosis (MC) in Germany. PATIENTS AND METHODS: From the year 2000 to 2003, a total of 4,814 subjects aged 45-75 years were included in the study. In 30 of the subjects (0.6%), determination of the ankle brachial index (ABI) was not possible, leaving 4,735 subjects (99.4%) in the data set. PAD was considered present in all subjects with an ABI < 0.9 in one leg, and/or a history of prior treatment for PAD. CLI was considered present if the highest ankle artery pressure measured < 70 mmHg. Prevalence of MC was calculated for ABI cut-off values of 1.3 and 1.5. FINDINGS: The overall prevalence of PAD according to the ABI criteria was 6.4% among men and 5.1% among women. After accounting for history of PAD, the prevalence increased to 8.2% among men and 5.5% among women. Taking the ABI criteria and medical history into account, males had a higher prevalence of PAD, with large increases in males aged 65-69 and 70-75 years. Chronic CLI was rare in the investigated population, and was found in only five older subjects (0.1%). With the criterion of ABI > 1.3, about 13.3% of males and 6.9% of females had MC. In contrast to PAD, the prevalence of MC did not increase with age. With the criterion of ABI > 1.5, MC was present in only 1.1% and 0.5% of men and women, respectively, but only 30 (0.6%) subjects had incompressible ankle arteries with a cuff pressure > 260 mmHg. CONCLUSION: Prevalences of PAD based only on ABI generally underestimate the true prevalence of PAD in population-based studies. CLI predominantly affects older subjects. In addition, cut-off values for MC must be newly determined.

Aged↗
PubMed2006

Problem focused integration of information, quality and process management with empirical research: The example of the Essen Interdisciplinary Pressure Ulcer Project.

Issues of information management, quality management, process management, and empirical research are often seen independently from each other. In the Essen interdisciplinary pressure ulcer project, they were integrated to establish a synergy between quality of care, economics and research. The electronic documentation of events and supplementary information was done with the hospital wide patient administration system. Feedback and automatically requests were used for quality improvement. Codes for reimbursement are generated from the clinical documentation. Research studies had been based on the routine documentation. Prerequisite was the cooperation of all relevant groups, nurses, physicians, informaticians, theoreticians and medical controller. In the future, it will be necessary to extend the approach to other relevant nursing problems and to replace the redundant documentation (paper-based as well as electronic) by an electronic health record.

Empirical Research↗
PubMed2005

Total-body 3D magnetic resonance angiography influences the management of patients with peripheral arterial occlusive disease.

High-resolution total-body 3D MR angiography (MRA) has recently become available, revealing additional clinically relevant disease in patients with peripheral arterial occlusive disease (PAOD). However, the actual impact of total-body MRA on patient management in patients with PAOD has not been investigated so far. Two hundred forty-nine consecutive patients with angiographically proven PAOD were prospectively examined by means of contrast-enhanced total-body 3D MRA on a 1.5-T MR scanner. All correlative imaging studies performed within 60 days of total-body MRA were included in the efficacy analysis. Additional clinically relevant disease (luminal narrowing >50%, aneurysmal changes or dissections) was found in 73 segments (52 patients), including the renal arteries (36 segments), carotid arteries (28 segments), subclavian arteries (four segments) and abdominal aortic aneurysms (AAA) (five segments). Of the 73 segments, 36 were deemed necessary for further investigation by means of focused MRA examinations; the diagnosis was confirmed in all cases. Within the 60-day follow-up period, interventional or surgical therapy outside the peripheral arterial tree was performed in nine patients (11 segments), including carotid endatherectomy and renal artery angioplasty. The outlined total-body 3D MRA approach permits a comprehensive evaluation of the arterial system in patients with atherosclerosis and does indeed have an impact on patient management in patients with PAOD.

Adult↗
PubMed2005

Positron emission tomography/computed tomography improves diagnostics of inflammatory arteritis.

Based on the unique property of fluorine-18 fluorodeoxyglucose, localization and follow-up of hypermetabolic processes is possible with positron emission tomography (PET). The dual-modality PET/computed tomography (CT) systems provide intrinsically fused morphologic and functional data in a single examination. We report on two patients with inflammatory aortitis and positive PET/CT findings. A 57-year-old woman with an inflammatory process involving the thoracolumbal aorta with an aneurysm and a 48-year-old woman with an aneurysm of the thoracic aorta and pronounced fluorodeoxyglucose-uptake. The advantages in differentiation of vessel wall structures compared with PET or CT alone are pointed out.

Aortic Aneurysm↗
PubMed2005

Pressure ulcers in secondary care: incidence, prevalence, and relevance.

OBJECTIVE: To compare point and period prevalence rates. DESIGN: Descriptive, cohort, cross-sectional survey. PARTICIPANTS: From a cohort of 25,075 cases, information on pressure ulcer status on admission was recorded for 20,283 cases. From 3237 selected cases, the pressure ulcer team made 2234 assessments. MAIN OUTCOME MEASURES: Point prevalence, period prevalence, and incidence rates. MAIN RESULTS: The cohort showed a period prevalence rate of 1.4% and an incidence rate of 0.6%. Patients with a pressure ulcer were older, were more likely to have had surgery, had longer hospital stays, and had a higher cost weight. The cross-sectional survey revealed a point prevalence rate of 5.3%. Patients within the cross-sectional survey had longer lengths of stay, were more likely to have had surgery, and presented a higher cost weight in comparison with the cohort. CONCLUSIONS: In an unselected hospital sample one can expect a period prevalence rate of 2% and a point prevalence rate of 10%. As demonstrated by the present study, differences between the 2 prevalence measurements are mainly due to the confounding of point prevalence rates by length of stay. Length of stay determines the probability of inclusion in a cross-sectional study and should be considered in pressure ulcer trials in the future.

Adolescent↗
PubMed2004

MR imaging of apparent small-bowel perfusion for diagnosing mesenteric ischemia: feasibility study.

The purpose of this study, which was approved by the institutional review board, was to assess the differentiation of individuals with from those without mesenteric ischemia. All subjects provided written informed consent. Six healthy volunteers and six patients with documented chronic mesenteric ischemia underwent magnetic resonance (MR) imaging with and without oral caloric stimulation. After intravenous administration of paramagnetic contrast material, signal intensity values of the small-bowel wall were measured up to 130 seconds after contrast material injection. Volunteers and patients, respectively, had maximum enhancement of the bowel wall between 70 and 85 seconds after contrast material administration that amounted to 269% and 267% without and 425% and 333% with caloric stimulation. MR imaging assessment of small-bowel perfusion is possible and seems feasible for differentiating individuals with from those without mesenteric ischemia.

Adult↗
PubMed2004

Value of plasma fibrin D-dimers for detection of acute aortic dissection.

OBJECTIVES: The purpose of this research was to assess the value of systemic inflammatory biomarkers in the detection of acute aortic dissection (AD). BACKGROUND: Rapid diagnosis and initiation of treatment is pivotal for patients with acute AD. So far, there is no laboratory test to aid the diagnosis. METHODS: Plasma fibrin D-dimers, white blood cell (WBC) count, C-reactive protein (CRP), and fibrinogen were determined in 64 chest-pain (CP) patients (acute AD, n = 16; pulmonary embolism [PE], n = 16; acute myocardial infarction [AMI], n = 16; non-cardiac CP, n = 16); 32 asymptomatic patients with chronic AD served as a control group. RESULTS: All acute AD patients showed highly elevated D-dimer values that were similar to PE patients (2,238 +/- 1,765 microg/l vs. 1,531 +/- 837 microg/l, p = 0.15) but significantly higher than in chronic AD, AMI, or CP patients (p < 0.001). The WBC count was significantly increased in patients with acute AD compared with the other groups (p < 0.001); in addition, CRP values differed only non-significantly from PE patients(p = 0.71). There were no differences in the fibrinogen levels between the groups. CONCLUSIONS: D-dimers are highly elevated in both acute PE and acute AD. Patients with acute AD show significant systemic inflammatory reactions. Measurement of D-dimers may be a valuable addition to the current diagnostic work-up of patients with suspected AD.

Acute Disease↗
PubMed2004

[Role of lipid lowering therapy in patients with peripheral arterial occlusive disease].

BACKGROUND: Peripheral arterial occlusive disease (PAOD) is common in older age. PAOD is associated with an increased risk of vascular events (e. g. myocardial infarction or stroke). Therefore, the prevention and treatment of PAOD is important, especially at a time when the elderly population is increasing. There is an association between lipid abnormalities and the risk of developing PAOD. However, it is not yet definitively established if early intervention with lipid lowering drugs prevents the development of PAOD and improves outcome. RESULTS OF STUDIES: In a 5-year follow-up study, in which hypercholesterolemia was treated by partial ileal bypass (POSCH study), the incidence of claudication was reduced to 19% (n = 126) in the surgical treatment group vs. 33.6% (n = 119) in the control group (p < 0.01). Direct imaging of peripheral atherosclerosis was not performed and a partial ileal bypass operation is followed by considerable changes in nutrition. A 2-year follow-up study of 153 patients with femoral atherosclerosis treated with colestipol-niacin demonstrated a decreased progression of angiographically assessed femoral atherosclerosis (p < 0.02). A subgroup analysis of the Scandinavian Simvastatin Survival Study (n = 4,444) reported worsening symptoms in 3.6% in the placebo group as compared to 2.3% in the simvastatin group (p = 0.008). In an open trial lipid-lowering therapy with statins did not improve functional outcomes including 6 minutes walking distance and 4 minutes walking velocity in 392 men and women with an ankle-brachial-index (ABI) < 0.90. A summary performance score combined performance in walking speed, standing balance, and time for five repeated chair rises into an ordinal score ranging from 0 to 12 (12 = best) was improved (p < 0.001). A randomized placebo controlled prospective study with simvastatin including 43 patients in each group demonstrated an improved painfree and total walking distance as well as an increased ABI after 6 months. A second placebo controlled study investigated the effect of 10 mg and 80 mg atorvastatin in 354 patients after 12 months. Painfree walking time was only improved by 80 mg atorvastatin, maximum walking time and ABI remained unchanged. A questionnaire regarding physical activity showed improved results already for 10 mg atorvastatin, whereas quality of life did not change. Pathomechanistic explanations, such as regression of peripheral atherosclerosis, were not described. CONCLUSION: All in all the association between the progression of PAOD and lipid abnormalities is surprisingly inconclusive and the effects of lipid-lowering are not defined. Well designed long-term studies assessing primary and secondary prevention of PAOD with defined endpoints, such as amputation rate or number of vascular interventions are missing. The mechanisms improving physical activity whithout affecting PAOD outcome have to be investigated.

Anticholesteremic Agents↗
PubMed2004

Impact of age, height, and body mass index on arterial diameters in infants and children: a model for predicting femoral artery diameters prior to cardiovascular procedures.

PURPOSE: To measure common femoral artery (CFA) diameters in infants and children referred for cardiac catheterization and investigate if CFA diameters can be predicted upon the basis of age, body mass index (BMI), and height. METHODS: CFA diameters were measured in 84 infants and children (50 boys; age range 1- 220 months) referred for diagnostic or therapeutic cardiac interventions. Sonographic measurements were made in a supine position utilizing a 7.5-MHz linear transducer; diameters were defined as the intima to intima distance. Age was described in months and height in centimeters. The Spearman correlation coefficient (rho) was used to test the similarity of diameters between sides; the Pearson correlation coefficient (r) was used to analyze the influence of age, height, and BMI on CFA diameter. RESULTS: Diameters of the right and left CFA were similar (rho=0.951). Age and height were highly correlated (rho=0.956), but not BMI and height (rho=0.279). The best model was CFA diameter = -0.838 + 0.031 height + 0.046 BMI. Height was the most relevant determinant for CFA diameter (p<0.0001, 90% CI 0.027 to 0.036; BMI: p=0.093, 90% CI 0.001 to 0.090, and the intercept: p=0.032, 90% CI-1.475 to-0.200). CONCLUSIONS: Common femoral artery diameter can be sufficiently predicted from height and BMI of infants and children prior to femoral catheterization or surgical reconstruction.

Adolescent↗
PubMed2004

Biomechanical incompatibility of popliteal stent placement.

Peripheral stents or endografts in specific arterial segments are exposed to extreme mechanical stress. Despite high rates of primary technical success, mechanical bending due to knee joint flexion can limit long-term patency of stents or endografts in the popliteal artery or the femoropopliteal segment. Every stent or endograft responds differently to bending during knee joint flexion, which can be revealed only by functional investigation. Mechanical bending has to be considered in future studies to assess the influence of differences in stent design, material, or postinterventional drug treatment on the long-term patency of endoprostheses in the femoropopliteal segment. To demonstrate the concept of biomechanical incompatibility, we present several illustrations of different stent designs placed in the popliteal artery.

Arterial Occlusive Diseases↗
PubMed2004

Impact of gender on femoral access complications secondary to application of a collagen-based vascular closure device.

BACKGROUND: Vascular complications at the femoral access site continue to be a significant problem after cardiac catheterization procedures. It was the aim of the present study to assess the impact of gender on the incidence of severe femoral access complications following the application of a collagen-based vascular closure device after transfemoral catheterization procedures. METHODS: A total of 1,294 consecutive patients (977 male, 317 female) underwent closure of femoral access sites with 8F collagen-based vascular closure devices (Angioseal) immediately after diagnostic or interventional coronary catheterization procedures, independently of the coagulation status. All patients were closely monitored for the occurrence of complications during the following 24 hours. RESULTS: Between male and female patients, there was no difference in the technical performance of the device with successful deployment being achieved in 96.7% and 95.9%, respectively (p=0.60). Severe access complications were found to be significantly higher in female versus male patients (1.6% vs. 0.2%; Odds ratio 7.7, 95% confidence interval 1.5-40.1; p=0.015), although similar accomplishment of an immediate hemostasis was seen in 92.8% and 92.4% of male and female patients (p=0.98). CONCLUSION: Women show a significantly increased risk of developing severe femoral access complications secondary to the application of a collagen-based vascular closure device, although the overall incidence of these complications is relatively low. We speculate that the increased risk in women may be related to smaller arterial dimensions, which could be evaluated by femoral angiography prior to deployment of a closure device.

Adult↗
PubMed2003

Detection of atherosclerosis: systemic imaging for systemic disease with whole-body three-dimensional MR angiography--initial experience.

In 100 consecutive patients with peripheral vascular disease whole-body three-dimensional magnetic resonance (MR) angiography was performed by using the rolling table platform system with a 1.5-T MR unit and five three-dimensional MR angiographic data sets during 72 seconds (0.2 mol per kilogram of body weight of gadobenate dimeglumine). Apart from the proved peripheral vascular disease, additional clinically relevant disease was found in 33 segments in 25 patients as follows: renal arterial narrowing (n = 15), carotid arterial stenosis (n = 12), subclavian arterial stenosis (n = 2), and abdominal aortic aneurysms (n = 4). Confirmatory studies performed in 11 patients in this study revealed no false-positive or false-negative findings at examination.

Adult↗