Bimodal dialysis: an integrated approach to renal replacement therapy.

BACKGROUND: Peritoneal dialysis (PD) and hemodialysis (HD) are both widely used as sole therapies for end-stage renal disease (ESRD). There is still controversy over which (if either) is superior in terms of patient outcomes. Peritoneal dialysis offers the advantages of long, slow, continuous ultrafiltration and potentially enhanced protection of residual renal function (RRF). In contrast, HD offers superior solute removal at the cost of undesirable cardiovascular tolerance of high rates of sodium and water removal. The aim of this study was to investigate the clinical feasibility of offering a combined treatment of both modalities [bimodal dialysis (BMD)] to incident patients reaching ESRD. We set out to investigate if it might be possible to utilize the intrinsic advantages of both modalities within a setting of good patient acceptability. METHODS: We prospectively studied 8 patients. They were recruited in the pre-ESRD phase from a specialist low clearance clinic. An arteriovenous fistula was formed and peritoneal catheters were inserted. The BMD consisted of 2, 3-hour, high efficiency, euvolemic HD sessions per week in combination with 2 PD exchanges per day to provide a degree of solute clearance and all of the ultrafiltration. Adequacy was measured independently for each modality. Patients were followed using the standard range of evaluations in addition to RRF (by creatinine clearance and EDTA clearance), echocardiography (left ventricular mass and ventricular performance), treatment outcomes, patient symptoms, and complications. RESULTS: Mean time on BMD was 346 +/- 74.9 (range 245 - 431) days. Peritonitis rate was 21 months per episode (mean 0.6 +/- 0.9, 0 - 2 episodes per patient). Mean peritoneal ultrafiltration volume was 1.58 +/- 0.32 (1.3 - 2.1) L per day. Delivered Kt/V and weekly PD Kt/V did not change significantly. Patients' RRF was maintained over the study period, as were serum albumin and control of serum phosphorus. Blood pressure was controlled with a reduction in the number of antihypertensive agents. Left ventricular mass index reduced over the treatment period, from a mean of 194 +/- 31.2 (161 - 265) to 156 +/- 21.2 (138 - 189) g/m2 (p = 0.05). Ventricular performance remained unchanged over the study [ejection fraction 50.4 +/- 11.1 (38 - 67) % to 48 +/- 8.0 (48 - 67) %]. Mean time during BMD spent on HD alone was 4.2 +/- 6.9 (0 - 16) days, and on PD alone 9.2 +/- 10.6 (0 - 25) days. CONCLUSION: This study suggests that BMD is a feasible treatment for ESRD. It is associated with adequate solute removal and good hemodynamic/volume control, and allows increased treatment flexibility for coping with complications normally requiring recourse to unplanned HD with temporary central venous access.     

Evaluation of the thyroid nodule.

BACKGROUND: Thyroid nodules are common, yet treatment modalities range from observation to surgical resection. Because thyroid nodules are frequently found incidentally during routine physical examination or imaging performed for another reason, physicians from a diverse range of specialties encounter thyroid nodules. Clinical decision making depends on proper evaluation of the thyroid nodule. METHODS: The current literature was reviewed and synthesized. RESULTS: Current evidence allows the formulation of recommendations and a general algorithm for evaluating the incidental thyroid nodule. CONCLUSIONS: Only a small percentage of thyroid nodules require surgical management. Diagnosis and treatment selection require a risk stratification by history, physical examination, and ancillary tests. Nodules causing airway compression or those at high risk for carcinoma should prompt evaluation for surgical treatment. In nodules larger than 1 cm, fine-needle aspiration biopsy is central to the evaluation as it is accurate, low risk, and cost effective. Subcentimeter nodules, often found incidentally on imaging obtained for another purpose, can usually be evaluated by ultrasonography. Other laboratory and imaging evaluations have specific and more limited roles. An algorithm for the evaluation of the thyroid nodule is presented.     

Distance-adjusted motor threshold for transcranial magnetic stimulation.

OBJECTIVE: To examine the relationship between coil-cortex distance and effective cortical stimulation using transcranial magnetic stimulation (TMS) in the left and right motor cortex. We also compare the effect of coil-cortex distance using 50 and 70 mm figure-eight stimulating coils. METHODS: Coil-cortex distance was manipulated within each participant using 5 and 10 mm acrylic separators placed between the coil and scalp surface. The effect of cortical stimulation was indexed by resting motor threshold (MT). RESULTS: Increasing distance between the coil and underlying cortex was associated with a steep linear increase in MT. For each additional millimetre separating the stimulating coil from the scalp surface, an additional approximately 2.8% of absolute stimulator output (approximately 0.062 T) was required to reach MT. The gradient of the observed distance effect did not differ between hemispheres, and no differences were observed between the 50 and 70 mm TMS coils. CONCLUSIONS: Coil-cortex distance directly influences the magnitude of cortical stimulation in TMS. The relationship between TMS efficacy and coil-cortex distance is well characterised by a linear function, providing a simple and effective method for scaling stimulator output to a distance adjusted MT. SIGNIFICANCE: MT measured at the scalp-surface is dependent on the underlying scalp-cortex distance, and therefore does not provide an accurate index of cortical excitability. Distance-adjusted MT provides a more accurate index of cortical excitability, and improves the safety and efficacy of MT-calibrated TMS.     

A novel mutation in the last exon of ATRX in a patient with α-thalassemia myelodysplastic syndrome

Abstract:  We describe a patient with acquired alpha-thalassemia myelodysplastic syndrome (ATMDS). A previously healthy 66-year-old man presented with hemoglobin of 9.3 g/dL, mean corpuscular volume 59 fL, and a bone marrow aspirate with increased erythroid precursors and hypolobulated megakaryocytes. Hemoglobin H inclusions were seen in most red cells after 1% brilliant cresyl blue supravital stain of the peripheral blood. At the molecular level, we identified of a novel mutation in the most 3' exon of the ATRX gene ( C GA→ T GA substitution in codon 2407) resulting in a premature termination codon (p.R2407X). This case provides further evidence for a link between ATRX mutations and ATMDS, and suggests a possible role for the conserved Q-box element in ATRX function.     

Intracranial Angioplasty and Stenting in the Awake Patient

BACKGROUND AND PURPOSE: Endovascular treatment for intracranial atherosclerosis is evolving, but complications remain an issue. Most interventions are performed under general anesthesia, preventing intraprocedural clinical evaluations. We describe our approach to intracranial angioplasty and stenting, using local rather than general anesthesia, and intraprocedural neurological assessment. METHODS: We prospectively collected procedural and outcome information on all patients undergoing intracranial angioplasty and stenting. Patients underwent interventions under local anesthesia with mild intravenous sedation or analgesia only if needed. Intraoperative neurological evaluations were performed, and symptomatology was used to guide the interventional technique. RESULTS: Forty-eight arteries in 40 patients with a mean age of 65.2 years were treated. Thirty-two anterior and 16 posterior circulation segments were treated. Technical success was achieved in 100% of patients with reduction of the mean pretreatment stenosis from 85 +/- 8.6% to 7 +/- 10.1%. Stents were deployed in 40 segments; five patients were treated with drug-eluting stents. The cobalt-chromium coronary stents were the easiest to deliver. Thirty-seven patients were treated under local anesthesia and, of those, 61.4% experienced intraprocedural symptoms that led to some alteration of the interventional technique. Headache was the most common symptom, and, when persistent, it heralded the occurrence of subarachnoid hemorrhage. There were seven total neurological complications, but only five (10.5%) led to permanent morbidity (4 strokes) or mortality (1 death). CONCLUSIONS: Intracranial angioplasty and stenting can be successfully performed using coronary techniques and equipment including drug-eluting stents. Local anesthesia permits neurological evaluations and often leads to the adjustment of the interventional technique, potentially making the procedure safer.     

EEG source imaging: correlating source locations and extents with electrocorticography and surgical resections in epilepsy patients.

SUMMARY: It is desirable to estimate epileptogenic zones with both location and extent information from noninvasive EEG. In the present study, the authors use a subspace source localization method (FINE), combined with a local thresholding technique, to achieve such tasks. The performance of this method was evaluated in interictal spikes from three pediatric patients with medically intractable partial epilepsy. The thresholded subspace correlation, which is obtained from FINE scanning, is a favorable marker, which implies the extents of current sources associated with epileptic activities. The findings were validated by comparing the results with invasive electrocorticographic (ECoG) recordings of interictal spike activity. The surgical resections in these three patients correlated well with the epileptogenic zones identified from both EEG sources and ECoG potential distributions. The value of the proposed noninvasive technique for estimating epileptiform activity was supported by satisfactory surgery outcomes.     

Respiratory sinus arrhythmia during speech production.

The amplitude of the respiratory sinus arrhythmia (RSA) was investigated during a reading aloud task to determine whether alterations in respiratory control during speech production affect the amplitude of RSA. Changes in RSA amplitude associated with speech were evaluated by comparing RSA amplitudes during reading aloud with those obtained during rest breathing. A third condition, silent reading, was included to control for potentially confounding effects of cardiovascular responses to cognitive processes involved in the process of reading. Calibrated respiratory kinematics, electrocardiograms (ECGs), and speech audio signals were recorded from 18 adults (9 men, 9 women) during 5-min trials of each condition. The results indicated that the increases in respiratory duration, lung volume, and inspiratory velocity associated with reading aloud were accompanied by similar increases in the amplitude of RSA. This finding provides support for the premise that sensorimotor pathways mediating metabolic respiration are actively modulated during speech production.