Vitamin C requirements in parenteral nutrition.

Some biochemical functions of vitamin C make it an essential component of parenteral nutrition (PN) and an important therapeutic supplement in other acute conditions. Ascorbic acid is a strong aqueous antioxidant and is a cofactor for several enzymes. The average body pool of vitamin C is 1.5 g, of which 3%-4% (40-60 mg) is used daily. Steady state is maintained with 60 mg/d in nonsmokers and 140 mg/d in smokers. Shocked surgical, trauma, and septic patients have a drastic reduction of circulating plasma ascorbate concentrations. These low concentrations require 3-g doses/d to restore normal plasma ascorbate concentrations, questioning the recommended PN dose of 100 mg/d. Determination of intravenous requirements is usually based on plasma concentrations, which are altered during the inflammatory response. There is no clear indicator of deficiency: serum or plasma ascorbate concentrations <0.3 mg/dL (20 micromol/L) indicates inadequate vitamin C status. On the basis of available pharmacokinetic data the 100 mg/d dose for patients receiving home PN and 200 mg/d for stable adult patients receiving PN are adequate, but requirements have been shown to be higher in perioperative, trauma, burn, and critically ill patients, paralleling oxidative stress. One recommendation cannot fit all categories of patients. Large vitamin C supplements may be considered in severe critical illness, major trauma, and burns because of increased requirements resulting from oxidative stress and wound healing. Future research should distinguish therapeutic use of high-dose ascorbic acid antioxidant therapy from nutritional PN requirements.

Bioimpedance for oedema evaluation after total knee arthroplasty.

BACKGROUND AND PURPOSE: Electrical bioimpedance spectroscopy (BIS) allows the evaluation of limb extracellular fluid (R0) and total fluid (Rinf). BIS could facilitate post-surgical oedema evaluation after total knee arthroplasty (TKA), as it is easily performed and is non-invasive. However, neither its applicability in this context nor the influence of metallic implants on measurement has been evaluated. The aim of this study was to evaluate the influence of TKA implants on the BIS R0 and Rinf variables used for oedema evaluation. METHOD: This was a prospective non-randomized comparative clinical trial. One oedema-free group of patients with TKA was compared with a group presenting similar characteristics except for the arthroplasty, to assess the influence of the implant on BIS measurement in the absence of oedema. The TKA group included 15 patients who had undergone surgery more than a year previously, and the control group included 19 patients awaiting TKA surgery. Volume and perimeter measurements served as reference criterions. The lower limb percentage differences for BIS, knee perimeter and volume were calculated. The significance of differences between groups was calculated for all measurement methods, using the Mann-Whitney test. The setting was a Department of Orthopedic Surgery and Traumatology in a university hospital. RESULTS: The differences between groups were not significant for R0, Rinf, volume and perimeter. R0 showed the smallest mean difference in limb percentage difference between groups [means (SD): TKA 3.98 (8.09), controls 3.97 (5.16)]. CONCLUSIONS: The lower-leg percentage difference in the TKA group is comparable with that of healthy subjects. R0 can be used for oedema evaluation following TKA surgery, as there was no sign of alteration from the metallic implant. These findings indicate the potential for early oedema evaluation after TKA. More research is warranted to extensively validate the application of BIS for oedema evaluation after TKA. Copyright © 2012 John Wiley & Sons, Ltd.

Investigating barriers in HIV-testing oncology patients. The IBITOP study: phase I.

BACKGROUND: Since the advent of combined antiretroviral therapy (ART), the incidence of non-AIDS-defining cancers (non-ADCs) among HIV-positive patients is rising. We previously described HIV testing rates of <5% in our oncology centre, against a local HIV prevalence of 0.4% (1). We have since worked with the Service of Oncology to identify, how HIV testing can be optimized, we have conducted a study on investigating barriers in HIV-testing oncology patients (IBITOP) among treating oncologists and their patients. METHODS: After an initial two-month pilot study to examine feasibility (2), we conducted the first phase of the IBITOP study between 1st July and 31st October 2013. Patients of unknown HIV status, newly diagnosed with solid-organ non-AIDS-defining cancer, and treated at Lausanne University Hospital were invited to participate. Patients were offered HIV testing as a part of their initial oncology work-up. Oncologist testing proposals and patient acceptance were the primary endpoints. RESULTS: Of 235 patients with a new oncology diagnosis, 10 were excluded (7 with ADCs and 3 of known HIV-positive status). Mean age was 62 years; 48% were men and 71% were Swiss. Of 225 patients, 75 (33%) were offered HIV testing. Of these, 56 (75%) accepted, of whom 52 (93%) were tested. A further ten patients were tested (without documentation of being offered a test), which gave a total testing rate of 28% (62/225). Among the 19 patients who declined testing, reasons cited included self-perceived absence of HIV risk, previous testing and palliative care. Of the 140 patients not offered HIV testing and not tested, reasons were documented for 35 (25%), the most common being previous testing and follow-up elsewhere. None of the 62 patients HIV tested had a reactive test. CONCLUSIONS: In this study, one third of patients seen were offered testing and the HIV testing rate was fivefold higher than that of previously observed in this service. Most patients accepted testing when offered. As HIV-positive status impacts on the medical management of cancer patients, we recommend that HIV screening should be performed in settings, where HIV prevalence is >0.1%. Phase II of the IBITOP study is now underway to explore barriers to HIV screening among oncologists and patients following the updated national HIV testing guidelines which recommend testing in non-ADC patients undergoing chemotherapy.

Intérêt du bleu de méthylène dans la chirurgie de l'hyperparathyroïdism primaire [Methylene blue in surgery of primary hyperparathyroidism]

Is surgery for primary hyperparathyroidism easier when methylene blue (MB) is given preoperatively? This retrospective study compares the durations of interventions for primary hyperparathyroidism carried out after i.v. MB administration to those when no MB was given. Over a period of 20 years (June 1976 to December 1996), 175 consecutive patients (56 men and 119 women, with ages ranging from 16 to 92, mean 59.6) were operated upon for primary hyperparathyrodism; 55 were operated before February 1986--the period when BM was introduced routinely, and 120 after. Thirty-two other patients were excluded from the study: 14 had had a previous cervicotomy and 18 another procedure in addition to the parathyroidectomy (usually on the thyroid gland), two conditions which prolonged the time devoted to parathyroid identification and excision. Preoperative calcemia averaged 2.97 mmol/L (2.34 to 4.59) and mean preoperative PTH was equal to 2.6 times the upper normal limit (0.5 to 24.1). Both groups were similar for as age, sex, preoperative calcium and PTH, and histologies. Methylene blue was administered intravenously (5 mg/kg diluted in 500 cc of 5% glucose) over a period of time of one hour starting two hours prior to surgery. All 175 procedures were performed by two surgeons and duration of surgery was recorded from the anesthesiologist's notes. There were 149 adenomas (85%), 24 hyperplasias (14%), a combination of both in two, and unspecified in two others. Except for a case of acute lower back pain synchronous to the injection of the dye (which was immediately stopped), MB was well tolerated. Mean duration for the 55 interventions performed without MB was 68 minutes (35 to 140, median 60), compared to 49 minutes for the 120 procedures carried out after MB had been given (20 to 155, median 45). Differences in operative, times were highly significant (p < 10(-6) and represented a gain of time of 27%. Surgery for primary hyperparathyroidism was significantly shorter when it was preceded by the administration of MB, a dye which facilitates the identification of pathologic parathyroid gland(s).