Johannes L. Willems

Accuracy of bedside glucose measurement from three glucometers in critically ill patients

Objective:Implementation of strict glucose control in most intensive care units has resulted in increased use of point-of-care glucose devices in the intensive care unit. The aim of this study was to determine the reliability of point-of-care testing glucose meters among critically ill patients under intensive insulin treatment. Design:Prospective observational study. Patients:Intensive care unit and non-intensive care unit patients in a tertiary care teaching hospital. Measurements:A glucose oxidase method was used to validate the point-of-care testing devices. Three different point-of-care testing devices, Accu-Chek Sensor (Roche Diagnostics), Precision (Abbott Diagnostics), and HemoCue were tested. Glucose measurements were performed in duplicate by an experienced technician under standardized conditions in the hospitals laboratory, using arterial (intensive care unit patients) and arterial or venous (non-intensive care unit patients) heparinized whole blood samples. Main Results:A strong correlation was found between the glucose oxidase method and the Accu-Chek device (r2 = .9596, p < 0.001). Mean absolute difference between the glucose oxidase and Accu-Chek was −0.32 mmol/L (95% confidence interval −0.84 to 1.48 mmol/L). Using the International Organization for Standardization (ISO) criteria, 27 of 197 samples (13.7%) were inaccurate. In all samples that failed to meet the ISO criteria, glucose values measured by the Accu-Chek device were higher compared with the glucose oxidase method. In another set of experiments among intensive care unit patients, strong positive correlations were also found between the other point-of-care testing devices and the glucose oxidase method. However, paired samples from Accu-Chek, HemoCue, and Precision failed the ISO criteria in 9 of 82 (11.0%), 4 of 82 (4.9%), and 11 of 82 (13.4%) of cases, respectively. In non-intensive care unit patients paired samples from Accu-Chek, HemoCue, and Precision failed the ISO criteria in 3 of 120 (2.5%), 11 of 120 (9.2%), and 16 of 120 (13.3%) cases, respectively. Conclusions:Under standardized conditions, glucose results from three point-of-care testing devices were inaccurate in both intensive care unit and non-intensive care unit patients. Among intensive care unit patients, inaccurate glucose readings were most frequently falsely elevated, resulting in misinterpretation of high glucose values with subsequent inappropriate insulin administration or masking of true hypoglycemia.

Proteomic profiling and identification in peritoneal fluid of children treated by peritoneal dialysis

BACKGROUND Proteomic technologies offer a high-throughput analysis of the expression of proteins in biological samples. The global analysis of the proteins in peritoneal dialysis (PD) fluid will provide a better understanding of the biological processes of the peritoneal membrane. METHODS The dialysate of nine paediatric PD patients was collected from peritoneal equilibrium tests with 3.86% glucose. Proteins were separated on a 10% SDS-PAGE gel and in-gel digested with trypsin. Peptide mixtures were analysed using nanoLC-MS/MS and results were searched against the NCBI database. RESULTS A total number of 189 proteins were identified in the PD fluid of nine patients, with 88 proteins shared by all patients. These 88 proteins accounted for 47% of the identified proteins and >90% of the total protein content in the analysed samples. Proteins were subdivided into eight different classes according to function. CONCLUSIONS This study gives a representative overview of the proteins present in PD fluid. The proteins in PD fluid reflect plasma proteins as well as local peritoneal processes. Potentially interesting proteins are revealed.

Estimated glomerular filtration rate in the nephrotic syndrome

BACKGROUND Plasma creatinine concentration and creatinine-based equations are most commonly used as markers of glomerular filtration rate (GFR). The abbreviated MDRD formula is considered the best available formula. Altered renal handling of creatinine, which may occur in the nephrotic syndrome, will invalidate creatinine-based formulas. We have evaluated the abbreviated MDRD formula in a large cohort of patients with proteinuria. METHODS Data on a cohort of patients with glomerular diseases were available from a large database. We have studied the relationship between estimated GFR (MDRD formula), and plasma cystatin C (CysC) and plasma beta-2-microglobulin (β2m) as markers of GFR. RESULTS The final analysis included 142 patients (93 M/49 F), median age 48 years (±15), plasma creatinine 101 μmol/L (42-368), plasma albumin 28.0 g/L (10.0-47.0), proteinuria 6.4 g/day (0.03-37.9), eGFR-MDRD4 64 mL/min/1.73 m2 (15-165), β2m 3.43 mg/L (0.7-13.8) and CysC 1.14 mg/mL (0.56-4.00). As expected, we observed a hyperbolic relationship between eGFR and both β2m and CysC. In multivariable analysis, plasma albumin concentration proved to be the most important predictor of the relationship between eGFR and both CysC and β2m. In the presence of hypoalbuminaemia, eGFR was ~ 30-40% higher at equal levels of plasma CysC or β2m. Conclusions were similar when using the recently developed CKD-EPI formula. Plasma albumin concentration did not effect the relationship between eGFR estimated by the six-variable original MDRD formula and β2m. CONCLUSIONS Our data point to discrepancies between eGFR using the six-variable MDRD formula and eGFR using the abbreviated MDRD formula as well as the CKD-EPI formula in patients with hypoalbuminaemia. One should be aware of possible limitations of creatinine-based eGFR formulas in patients with a nephrotic syndrome.

Self-sustained Aeroacoustic Oscillations in Multiple Side-Branch Pipe Systems

ow along closed side branches of the pipe system. The investigation of this phenomenon is carried out on a scale model. Since the scale model shows an acoustic behavior similar to the compressor station it is used in order to characterize some of the design parameters that are inuencing the aeroacoustic behavior of the pipe network. These parameters are the shape of the edges at the junction between the side branches and the main pipe, the depth of the side branches and the geometrical symmetry of the system. The resonance modes of the pipe network are predicted by means of a plane wave acoustic model. A model for the evaluation of the global maximum pulsation amplitude from the knowledge of a local maximum pulsation amplitude is then presented.

CDC91L1 (PIG-U) mRNA expression in urothelial cell carcinomas.

CDC91L1 (PIG‐U) was recently discovered as a new oncogene in human bladder cancer and showed mRNA overexpression in 36% of primary bladder tumor tissues compared to normal urothelium. We further investigated CDC91L1 mRNA expression in 8 bladder cancer cell lines, 14 normal bladder tissues and 42 urothelial cell carcinomas by real‐time quantitative PCR. The prognostic value of CDC91L1 mRNA expression was also investigated. Surprisingly, only one (2.4%) tumor tissue showed overexpression compared to normal urothelium. No significant relationship of CDC91L1 mRNA expression with increasing pathologic stage (p = 0.962) or grade (p = 0.557) was observed. Median normalized CDC91L1 mRNA expression values were 0.19 for superficial tumors (n = 21) and 0.18 for invasive tumors (n = 21). Grade I, grade II and grade III tumors had median normalized expression values of 0.26, 0.18 and 0.33, respectively. CDC91L1 mRNA expression level was not indicative of early tumor recurrence (log rank p = 0.1629), tumor progression (log rank p = 0.9307) or overall and disease‐specific survival (log rank p = 0.9193 and 0.4710, respectively). Our results suggest, in contrast to those of Guo et al. (Nat Med 2004;10:374–81), that the oncogene CDC91L1 is not overexpressed at the mRNA level in urothelial cell carcinomas and cannot be used to predict the course of the disease.

PRE-TREATMENT OF DAIRY AND BREAST MILK WITH SEVELAMER HYDROCHLORIDE AND SEVELAMER CARBONATE TO REDUCE PHOSPHATE

♦ Introduction: Young children and infants with chronic kidney disease are at increased risk of hyperphosphatemia because of high intake of dairy products. Hyperphosphatemia leads to metastatic calcifications and an increased risk of cardiovascular complications. Sevelamer is an effective phosphate binder, but for children it has important practical disadvantages: it clogs enteral feeding tubes and can cause gastrointestinal complaints. Pre-treatment of dairy products to reduce their phosphate content might solve those problems. ♦ Methods: Sevelamer hydrochloride and sevelamer carbonate were suspended in various dairy products (cow’s milk, breast milk, baby formula, and tube-feeding formula). Each product was tested with varying concentrations of sevelamer. After suspension, each sample was stored for 10 minutes, allowing the sevelamer to precipitate. The supernatant was decanted and analyzed for pH and for phosphate, calcium, magnesium, potassium, sodium, and chloride content. ♦ Results: We observed a significant decrease in the phosphate content of all tested products. With sevelamer hydrochloride, the phosphate reduction was 48% - 91% in the various products, and with sevelamer carbonate, it was 22% - 87%. The highest effectiveness was found in breast milk. A pH increase was found in all products. With sevelamer hydrochloride, a significant increase in chloride occurred. Notably, a significant decrease in calcium content (-75%) was observed in treated breast milk. ♦ Conclusions: Pretreatment of a variety of dairy products with either sevelamer hydrochloride or sevelamer carbonate effectively reduced their phosphate content and might avoid troublesome ingestion of sevelamer in children. The change in pH with sevelamer hydrochloride was remarkable, reflecting buffering mechanisms. The reduction in the calcium content of breast milk is a potential concern and should be carefully considered and monitored during clinical use of sevelamer.

Cystatin C levels are unaltered in patients with diabetes mellitus and normal renal function.

To the Editor: In their recent article, Stevens et al.1 have reported that factors other than glomerular filtration rate (GFR) affect serum cystatin C (CysC) levels. Specifically, they mentioned the impact of diabetes mellitus, which was associated with 8.5% higher levels of CysC. However, proteinuria was also associated with CysC and, as admitted by the authors, diabetes and proteinuria were strongly associated in their patient cohorts. Thus, their data did not allow for determining the independent effects of diabetes mellitus or proteinuria. We have previously reported GFR data of a cohort of patients with normo-albuminuric diabetes type I and age- and sex-matched controls.2 From this cohort, we have selected 33 patients and 38 controls with matching GFR (inulin clearance) and evaluated the relationship between CysC and GFR.