CT arthrography of the glenohumeral joint: CT fluoroscopy versus conventional CT and fluoroscopy--comparison of image-guidance techniques.

PURPOSE: To compare examination time with radiologist time and to measure radiation dose of computed tomographic (CT) fluoroscopy, conventional CT, and conventional fluoroscopy as guiding modalities for shoulder CT arthrography. MATERIALS AND METHODS: Glenohumeral injection of contrast material for CT arthrography was performed in 64 consecutive patients (mean age, 32 years; age range, 16-74 years) and was guided with CT fluoroscopy (n = 28), conventional CT (n = 14), or conventional fluoroscopy (n = 22). Room times (arthrography, room change, CT, and total examination times) and radiologist times (time the radiologist spent in the fluoroscopy or CT room) were measured. One-way analysis of variance and Bonferroni-Dunn posthoc tests were performed for comparison of mean times. Mean effective radiation dose was calculated for each method with examination data, phantom measurements, and standard software. RESULTS: Mean total examination time was 28.0 minutes for CT fluoroscopy, 28.6 minutes for conventional CT, and 29.4 minutes for conventional fluoroscopy; mean radiologist time was 9.9 minutes, 10.5 minutes, and 9.0 minutes, respectively. These differences were not statistically significant. Mean effective radiation dose was 0.0015 mSv for conventional fluoroscopy (mean, nine sections), 0.22 mSv for CT fluoroscopy (120 kV; 50 mA; mean, 15 sections), and 0.96 mSv for conventional CT (140 kV; 240 mA; mean, six sections). Effective radiation dose can be reduced to 0.18 mSv for conventional CT by changing imaging parameters to 120 kV and 100 mA. Mean effective radiation dose of the diagnostic CT arthrographic examination (140 kV; 240 mA; mean, 25 sections) was 2.4 mSv. CONCLUSION: CT fluoroscopy and conventional CT are valuable alternative modalities for glenohumeral CT arthrography, as examination and radiologist times are not significantly different. CT guidance requires a greater radiation dose than does conventional fluoroscopy, but with adequate parameters CT guidance constitutes approximately 8% of the radiation dose.

L'hémodialyse intermittente aux soins intensifs = [Intermittent hemodialysis in the intensive care setting]

Acute renal failure is a frequent and potentially lethal disease in intensive care units. Renal replacement therapy (RRT) is often required. Either intermittent or continuous methods of RRT can be used. When to start a RRT and which method to use is not always clearly defined and a global evaluation of the clinical situation is required. The choice of the modality of RRT will be up to the general clinical context, hemodynamic stability, the type of molecules to be cleared and the haemorrhagic risk as much as habits and available resources. No study currently showed a superiority of either continuous or intermittent renal replacement therapy. The collaboration between intensive care specialists and nephrologists allows an optimized choice for a given patient and allow better move from one technic to another if required.

Parameters for successful monthly extended dosing of darbepoetin-alpha in patients undergoing hemodialysis.

AIM: To document the feasibility and report the results of dosing darbepoetin-alpha at extended intervals up to once monthly (QM) in a large dialysis patient population. MATERIAL: 175 adult patients treated, at 23 Swiss hemodialysis centres, with stable doses of any erythropoiesis-stimulating agent who were switched by their physicians to darbepoetin-alpha treatment at prolonged dosing intervals (every 2 weeks [Q2W] or QM). METHOD: Multicentre, prospective, observational study. Patients' hemoglobin (Hb) levels and other data were recorded 1 month before conversion (baseline) to an extended darbepoetin-alpha dosing interval, at the time of conversion, and once monthly thereafter up to the evaluation point (maximum of 12 months or until loss to follow-up). RESULTS: Data for 161 evaluable patients from 23 sites were included in the final analysis. At 1 month prior to conversion, 73% of these patients were receiving darbepoetin-alpha weekly (QW) and 27% of the patients biweekly (Q2W). After a mean follow-up of 9.5 months, 34% received a monthly (QM) dosing regimen, 52% of the patients were receiving darbepoetin-alpha Q2W, and 14% QW. The mean (SD) Hb concentration at baseline was 12.3 +/- 1.2 g/dl, compared to 11.9 +/- 1.2 g/dl at the evaluation point. The corresponding mean weekly darbepoetin-alpha dose was 44.3 +/- 33.4 microg at baseline and 37.7 +/- 30.8 microg at the evaluation point. CONCLUSIONS: Conversion to extended darbepoetin-alpha dosing intervals of up to QM, with maintenance of initial Hb concentrations, was successful for the majority of stable dialysis patients.

Wide-pulse-high-frequency neuromuscular stimulation of triceps surae induces greater muscle fatigue compared with conventional stimulation.

We compared the extent and origin of muscle fatigue induced by short-pulse-low-frequency [conventional (CONV)] and wide-pulse-high-frequency (WPHF) neuromuscular electrical stimulation. We expected CONV contractions to mainly originate from depolarization of axonal terminal branches (spatially determined muscle fiber recruitment) and WPHF contractions to be partly produced via a central pathway (motor unit recruitment according to size principle). Greater neuromuscular fatigue was, therefore, expected following CONV compared with WPHF. Fourteen healthy subjects underwent 20 WPHF (1 ms-100 Hz) and CONV (50 μs-25 Hz) evoked isometric triceps surae contractions (work/rest periods 20:40 s) at an initial target of 10% of maximal voluntary contraction (MVC) force. Force-time integral of the 20 evoked contractions (FTI) was used as main index of muscle fatigue; MVC force loss was also quantified. Central and peripheral fatigue were assessed by voluntary activation level and paired stimulation amplitudes, respectively. FTI in WPHF was significantly lower than in CONV (21,717 ± 11,541 vs. 37,958 ± 9,898 N·s P<0,001). The reductions in MVC force (WPHF: -7.0 ± 2.7%; CONV: -6.2 ± 2.5%; P < 0.01) and paired stimulation amplitude (WPHF: -8.0 ± 4.0%; CONV: -7.4 ± 6.1%; P < 0.001) were similar between conditions, whereas no change was observed for voluntary activation level (P > 0.05). Overall, our results showed a different motor unit recruitment pattern between the two neuromuscular electrical stimulation modalities with a lower FTI indicating greater muscle fatigue for WPHF, possibly limiting the presumed benefits for rehabilitation programs.

Intravenous streptomycin dosing regimen in a patient undergoing hemodialysis: Plasma level monitoring and pharmacokinetic simulation

Introduction: Streptomycin, as other aminoglycosides, exhibits concentration-dependent bacterial killing but has a narrow therapeutic window. It is primarily eliminated unchanged by the kidneys. Data and dosing information to achieve a safe regimen in patients with chronic renal failure undergoing hemodialysis (HD) are scarce. Although main adverse reactions are related to prolonged, elevated serum concentrations, literature recommendation is to administer streptomycin after each HD. Patients (or Materials) and Methods: We report the case of a patient with end-stage renal failure, undergoing HD, who was successfully treated with streptomycin for gentamicin-resistant Enterococcus faecalis bacteremia with prosthetic arteriovenous fistula infection. Streptomycin was administered intravenously 7.5 mg/kg, 3 hours before each dialysis (3 times a week) during 6 weeks in combination with amoxicillin. Streptomycin plasma levels were monitored with repeated blood sampling before, after, and between HD sessions. A 2-compartment model was used to reconstruct the concentration time profile over days on and off HD. Results: Streptomycin trough plasma-concentration was 2.8 mg/L. It peaked to 21.4 mg/L 30 minutes after intravenous administration, decreased to 18.2 mg/L immediately before HD, and dropped to 4.5 mg/L at the end of a 4-hour HD session. Plasma level increased again to 5.7 mg/L 2 hours after the end of HD and was 2.8 mg/L 48 hours later, before the next administration and HD. The pharmacokinetics of streptomycin was best described with a 2-compartment model. The computer simulation fitted fairly well to the observed concentrations during or between HD sessions. Redistribution between the 2 compartments after the end of HD reproduced the rebound of plasma concentrations after HD. No significant toxicity was observed during treatment. The outcome of the infection was favorable, and no sign of relapse was observed after a follow-up of 3 months. Conclusion: Streptomycin administration of 7.5 mg/kg 3 hours before HD sessions in a patient with end-stage renal failure resulted in an effective and safe dosing regimen. Monitoring plasma levels along with pharmacokinetic simulation document the suitability of this dosing scheme, which should replace current dosage recommendations for streptomycin in HD.

Salt subtraction in patients on maintenance hemodialysis. Efficacy and limitations.

In 6 hypertensive patients with terminal renal failure maintained on hemodialysis, the effects of 'salt subtraction' and of sequential ultrafiltrating were evaluated. Following each of 3 weekly hemodialysis sessions, salt subtraction was carried out by ultrafiltrating 1 liter and simultaneously infusing an equal volume of 5% dextrose. This resulted in a net sodium loss without hypovolemia. After a 2-week period of this procedure, the blood pressure prior to dialysis was lower (156/76 +/- 12/5 mm Hg) than after a comparable number of sequential ultrafiltration sessions (181/88 +/- 10/6 mm Hg; mean +/- SEM). This difference was not statistically significant. At the same time, body weight was comparable at 64.4 +/- 3 and 64.7 +/- 4 kg, respectively. Neither plasma renin activity nor plasma catecholamines responded with a clear increase to either procedure. The limited effect on blood pressure and the renin system of a marked sodium removal during salt subtraction suggests that sodium must still be present in excess in these patients. The procedure of salt subtraction appears safe and subjectively well tolerated, but it can probably not be used as the sole means of decreasing total body sodium without associating dietary measures to reduce sodium intake.

In vivo transformation of mouse conventional CD8alpha+ dendritic cells leads to progressive multisystem histiocytosis

Division and proliferation of dendritic cells (DCs) have been proposed to contribute to homeostasis and to prolonged antigen presentation. Whether abnormal proliferation of dendritic cells causes Langerhans cell histiocytosis (LCH) is a highly debated topic. Transgenic expression of simian virus 40 (SV40) T antigens in mature DCs allowed their transformation in vivo while maintaining their phenotype, function, and maturation capacity. The transformed cells were differentiated splenic CD8 alpha-positive conventional dendritic cells with increased Langerin expression. Their selective transformation was correlated with higher steady-state cycling compared with CD8 alpha-negative DCs in wild-type and transgenic mice. Mice developed a DC disease involving the spleen, liver, bone marrow, thymus, and mesenteric lymph node. Surprisingly, lesions displayed key immunohistologic features of Langerhans cell histiocytosis, including expression of Langerin and absence of the abnormal mitoses observed in Langerhans cell sarcomas. Our results demonstrate that a transgenic mouse model with striking similarities to aggressive forms of multisystem histiocytosis, such as the Letterer-Siwe syndrome, can be obtained by transformation of conventional DCs. These findings suggest that conventional DCs may cause some human multisystem LCH. They can reveal shared molecular pathways for human histiocytosis between humans and mice

Fish oil for prevention of sudden death in hemodialysis patients?

Friedman et al. report that hemodialysis patients with the highest levels of n-3 fatty acids had impressively low odds of sudden cardiac death. The study is limited by a small sample size, and the analysis relies on only a single baseline measurement of blood levels. Recent randomized evidence indeed fails to support that n-3 fatty acids may prevent sudden death in nonrenal patients. More evidence is needed to advocate fish oil in this setting.

Robotic Gait Training Is not Superior to Conventional Treadmill Training in Parkinson Disease: A Single-Blind Randomized Controlled Trial.

BACKGROUND: The use of robots for gait training in Parkinson disease (PD) is growing, but no evidence points to an advantage over the standard treadmill. METHODS: In this randomized, single-blind controlled trial, participants aged <75 years with early-stage PD (Hoehn-Yahr <3) were randomly allocated to 2 groups: either 30 minutes of gait training on a treadmill or in the Lokomat for 3 d/wk for 4 weeks. Patients were evaluated by a physical therapist blinded to allocation before and at the end of treatment and then at the 3- and 6-month follow-up. The primary outcome measure was the 6-minute walk test. RESULTS: Of 334 screened patients, the authors randomly allocated 30 to receive gait training with treadmill or the Lokomat. At baseline, the 2 groups did not differ. At the 6-month follow-up, both groups had improved significantly in the primary outcome measure (treadmill: mean = 490.95 m, 95% confidence interval [CI] = 448.56-533.34, P = .0006; Lokomat: 458.6 m, 95% CI = 417.23-499.96, P = .01), but no significant differences were found between the 2 groups (P = .53). DISCUSSION: Robotic gait training with the Lokomat is not superior to treadmill training in improving gait performance in patients with PD. Both approaches are safe, with results maintained for up to 6 months.

Asymptomatic high flow subclavian steal in a patient with hemodialysis access.

Subclavian steal phenomenon due to proximal subclavian artery stenosis or occlusion is not un-common but often remains asymptomatic. We describe the case of a 66-year-old man with end-stage renal disease hemodialysed through a brachio-brachial loop graft of the left forearm. Echo-Doppler precerebral examination showed a high reversed flow of 570 ml/min in the ipsilateral vertebral artery. After successful endovascular recanalization of the subclavian artery, access blood flow increased and vertebral flow decreased to 30 ml/min. Complete neurological examination was normal both before and after endovascular treatment. This case demonstrates how high a subclavian steal can be without causing symptoms and how well precerbral and cerebral circulation can adapt to hemodynamic changes.

Intermittent hemodialysis treatment in cefepime-induced neurotoxicity: Case report, pharmacokinetic modeling, and review of the literature.

Cefepime is a broad-spectrum cephalosporin indicated for in-hospital treatment of severe infections. Acute neurotoxicity, an increasingly recognized adverse effect of this drug in an overdose, predominantly affects patients with reduced renal function. Although dialytic approaches have been advocated to treat this condition, their role in this indication remains unclear. We report the case of an 88-year-old female patient with impaired renal function who developed life-threatening neurologic symptoms during cefepime therapy. She was treated with two intermittent 3-hour high-flux, high-efficiency hemodialysis sessions. Serial pre-, post-, and peridialytic (pre- and postfilter) serum cefepime concentrations were measured. Pharmacokinetic modeling showed that this dialytic strategy allowed for serum cefepime concentrations to return to the estimated nontoxic range 15 hours earlier than would have been the case without an intervention. The patient made a full clinical recovery over the next 48 hours. We conclude that at least 1 session of intermittent hemodialysis may shorten the time to return to the nontoxic range in severe clinically patent intoxication. It should be considered early in its clinical course pending chemical confirmation, even in frail elderly patients. Careful dosage adjustment and a high index of suspicion are essential in this population.

Virtual anthropology: A comparison between the performance of conventional X-ray and MDCT in investigating the trabecular structure of long bones.

Recently, modern cross-sectional imaging techniques such as multi-detector computed tomography (MDCT) have pioneered post mortem investigations, especially in forensic medicine. Such approaches can also be used to investigate bones non-invasively for anthropological purposes. Long bones are often examined in forensic cases because they are frequently discovered and transferred to medico-legal departments for investigation. To estimate their age, the trabecular structure must be examined. This study aimed to compare the performance of MDCT with conventional X-rays to investigate the trabecular structure of long bones. Fifty-two dry bones (24 humeri and 28 femora) from anthropological collections were first examined by conventional X-ray, and then by MDCT. Trabecular structure was evaluated by seven observers (two experienced and five inexperienced in anthropology) who analyzed images obtained by radiological methods. Analyses contained the measurement of one quantitative parameter (caput diameter of humerus and femur) and staging the trabecular structure of each bone. Preciseness of each technique was indicated by describing areas of trabecular destruction and particularities of the bones, such as pathological changes. Concerning quantitative parameters, the measurements demonstrate comparable results for the MDCT and conventional X-ray techniques. In contrast, the overall inter-observer reliability of the staging was low with MDCT and conventional X-ray. Reliability increased significantly when only the results of the staging performed by the two experienced observers were compared, particularly regarding the MDCT analysis. Our results also indicate that MDCT appears to be better suited to a detailed examination of the trabecular structure. In our opinion, MDCT is an adequate tool with which to examine the trabecular structure of long bones. However, adequate methods should be developed or existing methods should be adapted to MDCT.