Weighing the evidence: energy determinations across the spectrum of kidney disease.

Evidence based guidelines for medical nutrition therapy (MNT) in chronic kidney disease (CKD) recommend a range of caloric levels, dependent on age and level of kidney function. Recent literature has explored whether current research findings still support these earlier conclusions, and if new energy determinations for CKD are warranted. This review will take a brief look at the history of the controversy, examine the research evidence at the time of practice guideline development, investigate emerging research, and discuss implications for additional scientific inquiry.     

Adiabatic refocusing pulses for volume selection in magnetic resonance spectroscopic imaging.

Because of their excellent slice profiles and high immunity to RF inhomogeneity, adiabatic full passage (AFP) pulses are ideal for use in spatial localization. The nonlinear, position-dependent phase of a single AFP pulse generated during refocusing of transverse magnetization traditionally is eliminated by using identical pairs of AFP pulses, at the expense of increased RF power deposition and increased echo time (TE). Here it is shown that one can achieve significant phase refocusing by executing single AFP pulses along non-equivalent spatial axes. When used for volume selection in MR spectroscopic imaging (MRSI) the remaining nonlinear phase becomes inconsequential when the phase across a spectroscopic volume is small. Selection of rectangular and octagonal volumes is demonstrated with half the number of AFP pulses used in the traditional approach. It is shown that octagonal volume selection in the human brain provides excellent suppression of extracranial lipids, and thus allows multislice (1)H MRSI at 4 Tesla to be performed within the guidelines for RF power deposition.     

Randomized comparison between two microlaparoscopic techniques for partial salpingectomy.

OBJECTIVE: We compared 2 techniques for performing a partial salpingectomy by using microlaparoscopy and either bipolar coagulation or loop ligation. METHODS: A 3-mm transumbilical laparoscope with secondary midline port sites midway and suprapubically was used to perform a partial salpingectomy in 109 women desiring permanent sterilization. Each patient was randomly assigned to undergo a tubal resection either after Pomeroy ligation (n= 54) or after bipolar coagulation with Kleppinger forceps (n=55). Postoperative pain, as assessed using a 10-point visual analog scale, was the primary comparison endpoint. RESULTS: No technical difficulties with either technique required conversion to a minilaparotomy. The mean time to remove both tubal segments was not different between techniques (7 minutes, 21 seconds; range, 4 minutes, 25 seconds to 15 minutes, 43 seconds). Each segment (mean, 1.6 cm; range, 0.8 to 3.5 cm) was confirmed in the operating room, then histologically. Postoperative pain at 6 hours was scored similarly (median, ligation 4.6, coagulation 4.0 of 10). Outpatient recovery was the same, unless pelvic pain required overnight observation (ligation, 4 patients; coagulation, 2 patients). CONCLUSION: Partial salpingectomy, using microlaparoscopy with either bipolar coagulation or loop ligation, was performed with comparable ease, confirmation of the removed tube, and similar postoperative discomfort.     

Successful outcome with extended allograft ischemic time in pediatric heart transplantation.

BACKGROUND: Many cardiac transplant programs have liberalized donor eligibility criteria in an attempt to maximize donor supply and to accommodate increasing demand. Although many studies have evaluated the potential adverse effects of prolonged donor ischemic time (DIT) in adults undergoing cardiac transplantation, relatively few have focused specifically on pediatric recipients that include a substantial number of patients and long-term follow-up. The focus of this study was to examine the effect of extended DIT on mortality after pediatric heart transplantation. METHODS: We conducted a retrospective review of our pediatric cardiac transplant experience in the past 11 years, comparing patients who received allografts and had ischemic times >240 minutes with those who had ischemic times <240 minutes. RESULTS: A total of 129 pediatric patients (<19 years) underwent orthotopic heart transplantation, of whom 78 (60.5%) had DIT <240 minutes and 51 (39.5%) had DIT >240 minutes. We found no statistically significant difference in age, sex, race, height, weight, or donor age between the groups (p = not significant). Post-transplant survival at 1, 5, and 10 years was similar for both groups: 91.2%, 88.0%, and 85.2%, respectively, for patients with DIT <240 minutes vs 89.6%, 87.2%, and 79.8%, respectively, for patients with DIT >240 minutes (p = 0.433). Additionally, using Cox proportional hazard models, extended DIT >240 minutes was not a statistically significant independent predictor of post-transplant mortality (odds ratio, 0.655; 95% confidence interval, 0.518-0.972; p = 0.684; standard error = 0.468). CONCLUSION: Procurement of hearts from distant locations with associated extended DIT is justified in the setting of increased demand and a fixed donor population.     

Risk factors for decreased total body and regional bone mineral density in hemodialysis patients with severe secondary hyperparathyroidism.

Hyperparathyroidism contributes significantly to decreased bone mineral density (BMD) in end-stage renal disease patients, but this negative influence is not homogeneous throughout the skeleton. We studied the BMD by dual-energy X-ray absorptiometry on total body and on different regions of the skeleton in 42 patients with severe hyperparathyroidism on hemodialysis. We also evaluated the relationship between different risk factors and BMD found on the regions examined in these patients. The legs and other sites where cortical bone predominate were mostly affected, whereas trabecular bone was relatively preserved. This is probably the result of the different effects of hyperparathyroidism on cortical and trabecular bone, but we cannot rule out the interference of ectopic calcifications and sclerotic lesions of vertebral end-plates falsely increasing lumbar spine BMD. The main determinants of low total-body BMD were, in order of importance, immobility, high intact parathyroid hormone levels, low body mass index, and low albumin. Eleven patients presented with pathologic fractures, mainly in the legs, and BMD was lower in this group than in patients without fractures. In conclusion, our study makes clear that hyperparathyroidism is a great threat to bone density in hemodialysis patients, mainly in the legs, the site mostly affected by fragility fractures in our patients. Physicians must worry not only with high parathyroid hormone levels, but also with the nutritional state of these patients.     

Quality assurance, efficiency indicators and cost-utility of the evaluation workup for liver transplantation.

We report the results of a retrospective review of the outpatient pretransplantation workup for United Network for Organ Sharing (UNOS) 3 patients adopted at a liver transplantation (LT) center and illustrate the efficiency indicators used for quality evaluation and cost-analysis. A single-center, pre-LT evaluation workup was performed on an outpatient basis at a cost per patient evaluation of 2,770 Euros (). Objective measures were: the number of patients admitted to and excluded from each phase of the algorithm; the rate of patients admitted to pre-LT evaluation out of the total of referred patients (the referral efficiency rate); the rate of waitlisted patients out of those admitted to pre-LT evaluation (the evaluation efficiency rate); the rate of waitlisted patients out of those referred for LT (the process efficiency rate); and the cost per waitlisted patient, as the ratio of the cost per patient evaluation to the evaluation efficiency rate. From January 1, 1996, to October 1, 2004, 1,837 patients were referred for LT on an outpatient basis. Based on preemptive evaluation of the available clinical data, 412 patients (22.4%) were excluded from pre-LT evaluation and 1,425 (77.6%) were admitted to preliminary consultation. Among these, 603 (42.3%) were excluded from and 822 (57.7%) were admitted to pre-LT evaluation with a referral efficiency rate of 44.7% (822 of 1,837). Out of the patients evaluated for LT, 484 were waitlisted with a cost-utility and evaluation efficiency rate of 58.8% each (484 of 822). Of the 1,837 patients originally addressed for LT 484 were waitlisted, yielding a process efficiency rate of 26.3% (484 of 1,837) and a cost per waitlisted patient of 4,710.8. In conclusion, the 3 indicators allowed monitoring of the efficiency of the pre-LT evaluation algorithm. The current process efficiency rate at our center is low (26.3%), but avoiding early referrals we might increase it to 31.6%, with a 12% net saving on costs per waitlisted patient (from 4,710.8 to 4,165.4).     

Morphology of corneal nerves in soft contact lens wear. A comparative study using confocal microscopy

The aim of this study was to evaluate corneal innervation in soft contact lens wearers using the Tomey Confoscan confocal microscope (40x/0.75 objective lens). Three distinct age- and sex-matched subject groups were involved, including extended soft (hydrogel and silicone-hydrogel) contact lens wearers, overnight soft (hydrogel) contact lens wearers, and non contact lens wearers. A number of variables were objectively measured, subjectively evaluated, or graded in order to investigate the distribution and morphology of corneal nerves. For most of the evaluated parameters, no statistically significant differences were found. However, qualitative observations showed noticeable differences in corneal nerve appearance among the different subject groups; the degree of corneal oedema was suggested as the main causative factor. In conclusion, neither the short-term (overnight wear) nor the long-term (12-month extended wear) soft contact lens wear appeared to affect the morphology and/or distribution of corneal nerves as viewed with confocal microscopy.