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Biomedical subjects

R Vonthein

Publications and source records attributed to R Vonthein.

At least 19 recordsLinked to original sources
PubMed2006

Differentiation between malignant and benign solitary pulmonary nodules with proton density weighted and ECG-gated magnetic resonance imaging.

OBJECTIVE: To estimate performance of MRI for differentiating malignant from benign solitary pulmonary nodules (SPN) using morphological characteristics. MATERIAL AND METHODS: MRI in 46 patients with SPN (mean diameter: 19 mm) was carried out on 1.0 Tesla scanner using ECG-gated, gradient echo sequence. Morphological signs of SPN were determined and compared with previously performed helical-CT, where final diagnosis served as reference with 52% frequency of malignancy. Furthermore, three observers evaluated all images. RESULTS: Significant differences between the two groups were found for nodules shape, margin, inhomogeneity and the vessel-sign in MRI, nodules shape, margin, the vessel-sign, and presence of spicules in CT. Using these signs, AUC were 0.746 for MRI and 0.765 for CT. The mean sensitivity, specificity, and accuracy of observers for MRI/CT were 89%/95%, 42%/41%, 66%/68%, respectively. CONCLUSIONS: Despite discrepancies in morphologic appearance, no significant difference of accuracy between MRI and CT was determined. Further investigations are necessary to demonstrate the clinical use in combination with functional parameters, establishing MRI as a comprehensive diagnostic modality for SPN.

Adult↗
PubMed2006

Effect of visual restitution training on absolute homonymous scotomas.

The authors examined 16 patients with stable homonymous visual field defects (HVFDs) with static automated perimetry (SAP). Training effect E was defined as difference of the proportions of absolutely defective locations in all test locations, before and after visual restitution training (VRT). E was 0.05 +/- 0.05 (mean +/- SD). The authors observed a relevant training effect (E >or= 0.12) in two subjects, but only monocularly. VRT has little effect on absolute HVFDs in SAP.

Adult↗
PubMed2006

Remifentanil or sufentanil for coronary surgery: comparison of postoperative respiratory impairment.

BACKGROUND AND OBJECTIVE: High-dose opioid anaesthesia contributes to decreasing metabolic and hormonal stress responses in patients undergoing cardiac surgery. However, the increase in context-sensitive half-life of opioids given as a high-dose regimen can affect postoperative respiratory recovery. In contrast, remifentanil can be given in high doses without prolonging context-sensitive half-life due to its rapid metabolism. Therefore, we performed a prospective, randomized trial to compare anaesthesia consisting of propofol/remifentanil or propofol/sufentanil with regard to postoperative respiratory function and outcome. METHODS: Patients undergoing coronary artery bypass grafting were randomized to a propofol/remifentanil (0.5-1.0 microg kg(-1) min(-1)) or propofol/sufentanil (30-40 ng kg(-1) min(-1)) based anaesthetic. Carbon dioxide response, forced expiratory volume in one second, vital capacity, and functional residual capacity were measured 1 day prior to the operation, 1 h before extubation, 1, 24 and 72 h after extubation. In addition, the incidence of atelectasis, pulmonary infiltrates, intensive care unit and postoperative length of stay were compared. Patients and physicians were blinded to the treatment group. RESULTS: Twenty-five patients in each treatment group completed the study. There was no difference between patients of the treatment groups regarding demographics, risk- or pain scores. In all patients, carbon dioxide response, forced expiratory volume in one second, vital capacity and functional residual capacity were decreased postoperatively compared to baseline. Patients randomized to remifentanil had less depression of carbon dioxide response, less atelectasis and shorter postoperative length of stay (12 d vs. 10 d) than after sufentanil (P < 0.05). CONCLUSIONS: Intraoperative use of high-dose remifentanil for coronary artery bypass grafting may be associated with improved recovery of pulmonary function and shorter postoperative hospital length of stay than sufentanil.

Aged↗
PubMed2005

Is standardised (18)F-FDG uptake value an outcome predictor in patients with stage III non-small cell lung cancer?

PURPOSE: Recent studies have demonstrated the relevance of (18)F-FDG uptake as an independent prognostic factor for recurrence of operable non-small cell lung cancer (NSCLC). This corresponds with the experimental finding that FDG uptake correlates with the proliferative activity of tumour cells (Higashi et al., J Nucl Med 2000;41:85-92). On the basis of these observations, we studied the influence of FDG uptake on prognosis and occurrence of distant metastases in patients with advanced NSCLC. METHODS: One hundred and fifty-nine patients with NSCLC of UICC stage IIIA or IIIB were included in the study. In all patients, neoadjuvant treatment was planned to achieve operability. FDG PET was performed as an additional staging procedure prior to the initiation of therapy. Clinical outcome data in terms of overall survival, disease-free survival and incidence of distant metastases could be obtained for 137 patients and were correlated with the average standardised uptake value of the tumour (SUV(avg)). Furthermore, other factors influencing SUV(avg) and patient outcome (histological tumour type, grading, UICC stage, tumour size) were analysed. RESULTS: SUV(avg) was significantly influenced by tumour histology, UICC stage and tumour size. No significant difference could be shown for grading. In 38 out of the 159 patients (24%), FDG PET revealed previously unsuspected distant metastases. The incidence of distant metastases significantly correlated with SUV(avg). Overall survival tended to decrease with increasing SUV(avg); however, significance was only reached when a cut-off of 12.0 was applied (p=0.05). CONCLUSION: FDG uptake is an independent prognostic factor in patients with UICC stage III NSCLC, although less distinctively so than has been reported for stage I/II tumours.

Adult↗
PubMed2005

[Comparison of conventional full spine radiographs and fluoroscopic scanning method in young patients with idiopathic scoliosis].

PURPOSE: Evaluation of low-dose full spine radiographs using fluoroscopic images for the assessment of the Cobb angle measurement in patients with scoliosis. MATERIAL AND METHODS: Twenty-one consecutive patients (aged 10 - 27 years, mean age 14 years) with a conventional full spine examination (film speed class 800) underwent a follow-up exam using digital pulsed fluoroscopy (Multi Diagnost 4, Philips Medical Systems, Eindhoven, The Netherlands). The mean follow-up was 9 months. During a synchronized scan with a C-arm speed of 4 cm/sec fluoroscopic images were stored with a pulsed frequency of 3 images per second. The single images were merged and reconstructed to one image with the software Easy Spine (Philips medical Systems, Eindhoven, The Netherlands). The corresponding dose-area product values (DAP) of both methods were compared. Three independent observers assessed Cobb angles and image quality for each technique. RESULTS: The mean DAP values for conventional imaging was 94.9 cGy x cm (2) and for fluoroscopy 7.8 cGy x cm (2), respectively. A significant dose reduction of 91.8 % (CI 91 % to 95 %) was calculated. The average absolute angle difference between the observers was found to be 2.7 degrees for conventional imaging and 2.4 degrees for the fluoroscopic method. Interobserver standard deviation of 2.9 degrees was lower than the 5.3 degrees for conventional images. Image quality was better in the conventional images. CONCLUSION: Using the scanning method, we could achieve a mean reduction of the radiation dose of 92 %, while the accuracy of the Cobb angle measurements was comparable for both techniques despite of reduced image quality of digital fluoroscopy.

Adolescent↗
PubMed2005

Olivocochlear activity and temporary threshold shift-susceptibility in humans.

STUDY OBJECTIVES: Animal studies (guinea pig, cat, chinchilla) have shown that activity of the medial olivocochlear efferents can exert noise-protective effects on the cochlea. It is not yet known whether such effects are also existent in humans. Olivocochlear activity can be estimated indirectly by contralateral suppression (CS) of otoacoustic emissions (OAE). MATERIAL AND METHODS: We measured Input/Output functions of distortion products of OAE (DPOAE), with and without contralateral acoustic stimulation by white noise, in 94 normal hearing young male subjects. Seven stimuli with L2 between 20 and 60 dB SPL and L1 = 39 dB + 0.4 L2 ("scissor paradigm") were used at f2 = 2, 3, 4, 5, and 6 kHz. The measurement was repeated 2 weeks later. In 83 subjects of the same group, pure tone audiometry was registered before and 6 minutes after shooting exercises to evaluate individual susceptibility to develop a temporary threshold shift (TTS). RESULTS: Test-retest repeatability of CS was generally good. CS averaged 0.98 dB SPL (SD 1.19 dB, median 0.56 dB). As expected, CS was greatest at low stimulus levels (median 1.06 dB at L2 = 20 dB, as compared with 0.33 dB at L2 = 60 dB). The smallest average CS was found at 4 kHz, and the greatest CS appeared at 2 kHz. A TTS occurred in 7 of 83 (8.5%) subjects. Statistical analysis did not reveal any correlation between the amount of CS and individual TTS susceptibility. CONCLUSIONS AND OUTLOOK: 1) Measurement of CS of DPOAE using an extensive measurement paradigm revealed good test-retest repeatability, confirming the reliability of this audiologic tool. 2) CS of DPOAE does not predict individual susceptibility to mild TTS induced by impulse noise in humans. Possible explanations for the missing association are discussed. Future perspectives include longitudinal studies to further elucidate the association between medial olivocochlear bundle-activity and permanent threshold shift in humans. The goal is to develop a diagnostic tool for the prediction of individual noise vulnerability in humans, thereby preventing noise-induced hearing loss.

Acoustic Impedance Tests↗
PubMed2005

Does visual restitution training change absolute homonymous visual field defects? A fundus controlled study.

AIM: To examine whether visual restitution training (VRT) is able to change absolute homonymous field defect, assessed with fundus controlled microperimetry, in patients with hemianopia. METHODS: 17 patients with stable homonymous visual field defects before and after a 6 month VRT period were investigated with a specialised microperimetric method using a scanning laser ophthalmoscope (SLO). Fixation was controlled by SLO fundus monitoring. The size of the field defect was quantified by calculating the ratio of the number of absolute defects and the number of test points; the training effect E was defined as the difference between these two ratios before and after training. A shift of the entire vertical visual field border by 1 degrees would result in an E value of 0.14. RESULTS: The mean training effect of all right eyes was E = 0.025 (SD 0.052) and all left eyes E = 0.008 (SD 0.034). In one eye, a slight non-homonymous improvement along the horizontal meridian occurred. CONCLUSIONS: In one patient, a slight improvement along the horizontal meridian was found in one eye. In none of the patients was an explicit homonymous change of the absolute field defect border observed after training.

Adult↗
PubMed2005

Invasive pulmonary aspergillosis: frequency and meaning of the "hypodense sign" on unenhanced CT.

The purpose of this study was to establish the diagnostic value of central hypointensity ("hypodense sign") in lung consolidations or nodules, in severely immunocompromised or neutropenic patients, suspected of having invasive pulmonary aspergillosis (IPA), and to assess its recognition on unenhanced CT scans. Serial CT scans of the lung were retrospectively reviewed in 43 consecutive immunosuppressed patients with IPA, and assessed for the presence of the hypodense sign using standard mediastinal and lung windowing settings, as well as a special, narrower window setting (width 110-140 HU; level 15-40 HU). The temporal relationship between the occurrence of the first CT-finding suspicious of IPA and the appearance of the hypodense sign, as well as between this and the occurrence of the crescent sign, cavitation or reduction in lesion size, was evaluated. Additionally, CT-scans from 89 immunocompromised patients with viral (n=45) or bacterial (n=44) pneumonia, investigated in the same time period at our institution were reviewed, with respect to the presence of the "hypodense" sign. Unenhanced CT scans revealed the hypodense sign in 11 neutropenic patients and 2 severely immunocompromised patients, out of a total of 43 patients with IPA evaluated in this study (30.2%). The mean time between the appearance of the first CT-findings of IPA (large nodule or consolidation +/- positive halo sign) and the hypodense sign was 7.8 days, while the time interval between the hypodense sign and the occurrence of crescent sign, cavitation, or decrease of the lesion's size was 8.3 days. The hypodense sign did not occur in any of the patients with viral or bacterial pneumonia, in the control series. We consider the hypodense sign to be a supplementary tool in the diagnosis of IPA. Its sensitivity was low in our series, but the high specificity makes it valuable in predicting IPA, anticipating the occurrence of cavitation or crescent sign, which are considered specific, but late findings of IPA. The hypodense sign is recognizable also on unenhanced CT, when a narrower lung window setting is used.

Adolescent↗
PubMed2004

Influence of human recombinant interferon-alpha2a (rhIFN-alpha2a) on altered lymphocyte subpopulations and monocytes in Behcet's disease.

OBJECTIVE: In Behçet's disease (BD), several abnormalities of lymphocyte subpopulations have been described. Standard treatment comprises immunosuppressive drugs. We successfully treated 50 patients with ocular BD with interferon-alpha2a (IFN-alpha2a) (response rate 92%), although this is counterintuitive because IFN-alpha is immunostimulatory and can sometimes even induce autoimmune diseases such as systemic lupus erythematosus or rheumatoid arthritis. The aim of the present study was to elucidate the immunomodulatory effects that IFN-alpha might exert on peripheral blood mononuclear cells (PBMC) in BD by examining changes in the distribution of lymphocyte subpopulations under IFN-alpha2a treatment. METHODS: Fourteen patients with ocular BD were evaluated before and at weeks 4 and 24 of IFN-alpha treatment and compared with 10 healthy controls. PBMC were stained with monoclonal antibodies and measured by flow cytometry. RESULTS: Compared with the controls there is a significant elevation of monocytes (CD14(+)), CD8(+)/gammadelta T cells, CD3(+)/gammadelta T cells, natural killer (NK) cells (CD56(+)/CD16(+)) and activated/regulatory T cells (CD4(+)/CD25(+) and CD8(+)/CD25(+)) in patients with active BD before treatment with IFN-alpha2a. Numbers of naïve T cells (CD8(+)/CD45(+)RA(+)/RO(-), CD4(+)/CD45(+)RA(+)/RO(-)) were significantly lower. Under therapy, NK cells, CD8(+)/gammadelta T cells and CD3(+)/gammadelta T cells decreased significantly, whereas B cells increased. The previously reduced expression of HLA class I on monocytes in HLA-B51-positive patients rose to levels comparable to HLA-B51-negative patients. CONCLUSION: These results implicate the participation of NK cells and gammadelta T cells, especially CD8(+)/gammadelta T cells, in the pathogenesis of BD and may explain one mechanism by which IFN-alpha2a exerts therapeutic effects. Alternatively, they may result indirectly from remission induction by IFN-alpha2a. The reduced expression of HLA class I on monocytes in HLA-B*51-positive patients might reflect an impaired expression of and antigen presentation by HLA-B*51.

Adult↗
PubMed2004

[Evaluation of different 16-row CT colonography protocols using a porcine model].

PURPOSE: To develop and to test an easily produced biological colon model with simulated polypoid lesions. Application of this phantom for the selection of an optimized scan protocol of 16-row CT colonography (CTC) for clinical use. METHODS AND MATERIAL: Six polypoid lesions (1 - 6 mm) were simulated with sutures on the inner face of a porcine colon segment (20 cm). After distending the colon segment with air, the phantom was placed in a water quench and CT scans were performed on a MDCT-scanner (Somatom Sensation 16, Siemens, Forchheim). At constant values for collimation (16x0.75 mm) and voltage (120 kV), 54 different combinations of mAs values (50, 75 and 100 mAs), pitch factors (1, 1.25 and 1.5) and slice thicknesses (0.75, 1.0, 1.5, 2.0, 3.0 and 5.0 mm) were tested systematically. The phantom was scanned in the longitudinal and transverse axis to simulate the different orientation of the colon in the abdomen. Axial slice images and virtual endoscopic views of all data sets were presented separately to 2 radiologists who independently determined number and size of detectable polyps. Dose exposure was measured with an Alderson phantom. RESULTS: The colon model offered a realistic imitation of a polyp-covered, human colon. The experimental set-up allowed a systematic evaluation of polyp detection related to lesion size, orientation of the colon and CTC parameters, with other influencing factors mostly excluded. Polyps were significantly better detected in the longitudinal than in the transverse orientation of the colon. For the detection of lesions of at least 3 mm, a low dose (50 mAs) 16-row CTC should be combined with a pitch of 1.5 and a maximum slice thickness of 3 mm. For the depiction of polyps smaller than 3 mm, slice thickness and pitch should amount to 1 mm and 1.0, respectively. Effective dose of this low dose protocol is 4.08 mSv. CONCLUSION: The porcine colon phantom represents a realistic and easily produced alternative to other colonography models. It allows a preselection of a CTC-protocol for subsequent clinical testings. If the high in vitro performance of the low-dose 16-row CTC-protocol is confirmed on a human collective, the use of 16-row technique would represent a big step for CTC toward a screening method.

Animals↗
PubMed2003

Human recombinant interferon alfa-2a for the treatment of Behçet's disease with sight threatening posterior or panuveitis.

BACKGROUND: Behçet's disease is a multisystem vasculitis of unknown origin. Standard treatment mainly comprises systemic immunosuppressive agents. Ocular involvement, mostly posterior uveitis with retinal vasculitis, leads to blindness in 20-50% of the involved eyes within 5 years. The efficacy of interferon alfa-2a was studied in patients with sight threatening posterior uveitis or retinal vasculitis. METHODS: 50 patients were included in this open, non-randomised, uncontrolled prospective study. Recombinant human interferon alfa-2a (rhIFNalpha-2a) was applied at a dose of 6 million units subcutaneously daily. Dose reduction was performed according to a decision tree until discontinuation. Disease activity was evaluated every 2 weeks by the Behçet's disease activity scoring system and the uveitis scoring system. RESULTS: Response rate of the ocular manifestations was 92% (three non-responder, one incomplete response). Mean visual acuity rose significantly from 0.56 to 0.84 at week 24 (p<0.0001). Posterior uveitis score of the affected eyes fell by 46% every week (p<0.001). Remission of retinal inflammation was achieved by week 24. Mean Behçet's disease activity score fell from 5.8 to 3.3 at week 24 and further to 2.8 at week 52. After a mean observation period of 36.4 months (range 12-72), 20 patients (40%) are off treatment and disease free for 7-58 months (mean 29.5). In the other patients maintenance IFN dosage is three million units three times weekly. CONCLUSIONS: rhIFNalpha-2a is effective in ocular Behçet's disease, leading to significant improvement of vision and complete remission of ocular vasculitis in the majority of the patients.

Adult↗
PubMed2003

Chlamydia pneumoniae IgA seropositivity is associated with increased risk for atherosclerotic vascular disease, myocardial infarction and stroke in dialysis patients.

BACKGROUND: Atherosclerotic cardiovascular disease is the major cause of morbidity and mortality in patients with chronic renal failure undergoing dialysis therapy. Aim of the study was to evaluate whether there is a correlation between a past infection with Chlamydia pneumoniae inducing antibody production and the manifestation of symptomatic atherosclerotic disease in patients with chronic renal failure on hemodialysis. METHODS: A retrospective study was designed including 151 dialysis patients with a clinical apparent atherosclerotic disease (case subjects) and 116 dialysis patients without any symptomatic atherosclerotic manifestation (control group). An ELISA was used to measure seropositivity for IgA and IgG titers. RESULTS: Elevated IgA titers against Chlamydia pneumoniae were found in 67% of the case subjects, but only in 29% of the controls (OR 5.34, CI 2.98-9.56). Forty-five patients of the case subjects had a history of myocardial infarction (OR 5.14, CI 2.38-11.09). Prior stroke was found in 30 patients in case subjects (OR 4.37, CI 1.73-11.01). The follow-up after 3 years showed that only 20 patients died from cardiovascular disease in the control group in comparison to 57 patients in the case group (OR 2.51). IgG seropositivity revealed an OR of 1.02 (CI 1.0-2.1). CONCLUSION: These results indicate that IgA seropositivity is associated with an increased frequency of symptomatic atherosclerotic manifestations. Especially an increased number of patients was found with prior myocardial infarction or stroke when elevated IgA titers were detected. IgA positivity seems to be a separate prospective risk factor in patients with chronic renal failure and hemodialysis for premature cardiovascular death.

Aged↗
PubMed2002

[Imaging diagnosis of solitary pulmonary nodules on an open low-field MRI system--comparison of two MR sequences with spiral CT].

OBJECTIVE: To evaluate and compare two fast gradient-echo sequences (GRE) concerning the visualization of solitary pulmonary nodules with an open low-field MRI system in comparison to computed tomography. MATERIALS AND METHODS: Fourteen patients with solitary pulmonary nodules detected by spiral CT ranging in size from 6 mm to 42 mm (mean 20 mm) underwent MRI on an open 0.2 T scanner using a spoiled 2D GRE (2D FLASH; TR/ TE/Flip = 100 ms/7.5 ms/30 degrees ) and a totally refocused 2D steady-state GRE (True-FISP; TR/TE/FA = 7.3 ms/3.5 ms/80 degrees ). The image quality concerning artifacts (by flow, breathing and susceptibility) and the morphologic characteristics of the nodules were scored and compared with CT by two independent radiologists. The diameters of the nodules measured by MRI were compared with CT measurements. The sequences were also evaluated with regard to the signal-to-noise ratio (SNR) of the lesion. RESULTS: All lesions were detected with the 2D FLASH sequence. True-FISP failed to find a granuloma with a size of 6 mm. The 2D FLASH was rated significantly superior to true FISP concerning image quality artifacts by susceptibility as well as concerning to CT the presentation of nodule characteristics. In MR images, the size of lesions was significantly smaller than in CT images for both sequences: for 2D FLASH the mean difference was 0.9 mm and for true FISP 2.6 mm. The SNR of the nodules was significantly higher for the 2D FLASH than for the true FISP. CONCLUSION: In low field MRI, the 2D FLASH sequence is superior to the 2D true FISP sequence in imaging of pulmonary nodules. With the 2D FLASH sequence nodules of 6 mm or larger in size can be visualized.

Aged↗
PubMed2001

Reaction time in automated kinetic perimetry: effects of stimulus luminance, eccentricity, and movement direction.

PURPOSE: To determine the effects of stimulus eccentricity and luminance level on the reaction time (RT) of young normal volunteers during automated kinetic campimetry. METHODS: We used a specially designed video-campimetric device equipped with a continuous infrared (IR) pupillographic fixation control (Tübingen Computer Campimeter) and recorded reaction times upon presenting horizontally moving small circular stimuli (size 26'; constant angular velocity 2 degrees /s) starting at 16 locations within the central 30 degrees -radius of the visual field. Two different levels of stimulus luminance were used (41.6 cd/m(2) and 110 cd/m(2)), while background luminance was 10 cd/m(2). Each stimulus was presented a total of six times in a randomized order. Subjects were 12 healthy young individuals (aged 21-30 years) with normal ophthalmic examinations. An analysis of variance (ANOVA) was performed on the data. RESULTS: RTs showed considerable inter- and intra-individual variation with individual least squares means (LSM, fitted values of a linear model) ranging from 305 to 454 ms, and residual standard deviation (R.S.D.) 66 ms. Reaction times did not differ significantly as a function of stimulus direction (P>0.6). Higher luminance levels produced significantly reduced reaction times for all stimulus locations and directions (mean reduction: 16 ms; P<0.0001). Reaction times increased with increasing eccentricity, in the mean by 1.8 ms per degree of visual angle, from 365+/-4 ms (S.E.M.) foveally, to 407+/-2 ms at 30 degrees eccentricity; (P<0.0001). CONCLUSIONS: Automated kinetic perimetry should be designed to cope with significant, variable interindividual response characteristics. Other stimulus related factors, such as eccentricity or luminance level, have a significant but comparatively small effect on reaction time within the central 30 degrees -radius visual field in healthy young individuals.

Adult↗
PubMed2001

Enhanced detection criteria in implantable cardioverter defibrillators: sensitivity and specificity of the stability algorithm at different heart rates.

The lack of specificity in the detection of ventricular tachyarrhythmias remains a major clinical problem in the therapy with ICDs. The stability criterion has been shown to be useful in discriminating ventricular tachyarrhythmias characterized by a small variation in cycle lengths from AF with rapid ventricular response presenting a higher degree of variability of RR intervals. But RR variability decreases with increasing heart rate during AF. Therefore, the aim of the study was to determine if the sensitivity and specificity of the STABILITY algorithm for spontaneous tachyarrhythmias is related to ventricular rate. Forty-two patients who had received an ICD (CPI Ventak Mini I, II, III or Ventak AV) were enrolled in the study. Two hundred ninety-eight episodes of AF with rapid ventricular response and 817 episodes of ventricular tachyarrhythmias were analyzed. Sensitivity and specificity in the detection of ventricular tachyarrhythmias were calculated at different heart rates. When a stability value of 30 ms was programmed the result was a sensitivity of 82.7% and a specificity of 91.4% in the detection of slow ventricular tachyarrhythmias (heart rate < 150 beats/min). When faster ventricular tachyarrhythmias with rates between 150 and 169 beats/min (170-189 beats/min) were analyzed, a stability value of 30 ms provided a sensitivity of 94.5% (94.7%) and a specificity of 76.5% (54.0%). For arrhythmia episodes > or = 190 beats/min, the same stability value resulted in a sensitivity of 78.2% and a specificity of 41.0%. Even when other stability values were taken into consideration, no acceptable sensitivity/specificity values could be obtained in this subgroup. RR variability decreases with increasing heart rate during AF while RR variability remains almost constant at different cycle lengths during ventricular tachyarrhythmias. Thus, acceptable performance of the STABILITY algorithm appears to be limited to ventricular rate zones < 170 beats/min.

Aged↗
PubMed2001

Self-reported exercise before age 40: influence on quantitative skeletal ultrasound and fall risk in the elderly.

OBJECTIVES: To compare musculoskeletal factors with bone structure, as measured by quantitative ultrasound (QUS) at the calcaneus, and their potential to predict fall risk in geriatric inpatients. DESIGN: Longitudinal. SETTING: Two geriatric hospitals in Switzerland. PARTICIPANTS: A total of 134 of 207 long-stay geriatric patients (96 women, 38 men) who were able to perform the timed up and go (TUG) test. INTERVENTIONS: Five musculoskeletal tests: 2 functional tests (TUG, for mobility; functional reach test, for balance), and 3 muscle strength tests (knee flexor, knee extensor, grip). Falls were monitored prospectively in a subgroup of 94 mobile subjects of 1 geriatric hospital throughout each individual length of stay (median, 31.4wk: interquartile range, 16-56.4wk). MAIN OUTCOME MEASUREMENTS: Functional and strength tests, mobility status, and self-reported exercise before age 40 were musculoskeletal factors to be compared with QUS. RESULTS: QUS was higher in mobile subjects without walking aid (p < .0001) and correlated significantly with muscle strength (knee flexor: r = .36; knee extensor: r = .30) and functional tests (TUG: r = -.25; functional reach: r = .16). Women who reported regular exercise before age 40 had higher QUS (p = .01) and fewer falls (p = .01). Falls were less frequent in subjects with walking aid (p = .03). No single musculoskeletal test, but rather a combination of demographic variables, musculoskeletal factors, and QUS could predict 76% of total variation of fall risk. CONCLUSION: This study showed the important impact of current mobility and muscle strength status on bone structure, as measured by QUS at the calcaneus. In addition, a beneficial effect of former exercise on QUS and fall risk at advanced age could be documented in women. Both findings support life-long engagement in exercise, which might be particularly meaningful for women.

Accidental Falls↗
PubMed2001

[Evaluation of extensive visual field defects with computer-assisted kinetic perimetry].

BACKGROUND: Conventional kinetic perimetry is of especial use in case of advanced scotoma. However, examiner dependency is a major drawback. Purpose of this study was to evaluate the clinical feasibility and intraindividual scatter of computer-assisted kinetic perimetry in monitoring advanced visual field defects of various origins. METHODS: Examinations were carried out with the Tuebingen Computer Campimeter (background lumincance 10 cd/m2). In an initial session, the localization of the scotoma border is estimated with conventional manual kinetic perimetry. In the subsequent computer assisted kinetic mode, an individually adjusted set of vectors is designed. Each vector crosses the manually assessed visual field defect border almost perpendicularly, starting approximately 3 degrees within the scotoma. Each individual set of vectors can be stored and recalled for follow-up. Stimuli move along these vectors with identical characteristics as in manual kinetic perimetry. Stimulus presentations are repeated six times in a randomized order. Patients' responses are recorded and additionally corrected for mean individual reaction time. A "local kinetic threshold" (mean) and a related parameter for dispersion (standard deviation) are assessed. RESULTS: Four subjects with advanced visual field loss of various origin (retinitis pigmentosa, vigabatrin-associated visual field defect, glaucomatous nerve fibre layer defect, and postgeniculate visual pathway defect) participated in this study. Maximal difference between manual-kinetic and automated kinetic thresholds reaches from 1.7 degrees to 5 degrees. Local scatter (standard deviation) of kinetic threshold, assessed by computer-assisted perimetry, varies between 0.1 degree and 3.0 degrees. CONCLUSION: Computer assisted kinetic perimetry is a new, useful, examiner-independent, reliable method for effective evaluation and monitoring of advanced visual field loss.

Adult↗