Metrology in medicine: from measurements to decision, with specific reference to anesthesia and intensive care.

Metrology is the science of measurements. Although of critical importance in medicine and especially in critical care, frequent confusion in terms and definitions impact either interphysician communications or understanding of manufacturers' and engineers' instructions and limitations when using devices. In this review, we first list the terms defined by the International Bureau of Weights and Measures regarding quantities and units, measurements, devices for measurement, properties of measuring devices, and measurement standards. The traditional tools for assessing the most important measurement quality criteria are also reviewed with clinical examples for diagnosis, alarm, and titration purposes, as well as for assessing the uncertainty of reference methods

Day and night home closed-loop insulin delivery in adults with type 1 diabetes: three-center randomized crossover study.

OBJECTIVE: To evaluate the feasibility of day and night closed-loop insulin delivery in adults with type 1 diabetes under free-living conditions. RESEARCH DESIGN AND METHODS: Seventeen adults with type 1 diabetes on insulin pump therapy (means ± SD age 34 ± 9 years, HbA1c 7.6 ± 0.8%, and duration of diabetes 19 ± 9 years) participated in an open-label multinational three-center crossover study. In a random order, participants underwent two 8-day periods (first day at the clinical research facility followed by 7 days at home) of sensor-augmented insulin pump therapy (SAP) or automated closed-loop insulin delivery. The primary end point was the time when sensor glucose was in target range between 3.9 and 10.0 mmol/L during the 7-day home phase. RESULTS: During the home phase, the percentage of time when glucose was in target range was significantly higher during closed-loop compared with SAP (median 75% [interquartile range 61-79] vs. 62% [53-70], P = 0.005). Mean glucose (8.1 vs. 8.8 mmol/L, P = 0.027) and time spent above target (P = 0.013) were lower during closed loop, while time spent below target was comparable (P = 0.339). Increased time in target was observed during both daytime (P = 0.017) and nighttime (P = 0.013). CONCLUSIONS: Compared with SAP, 1 week of closed-loop insulin delivery at home reduces mean glucose and increases time in target without increasing the risk of hypoglycemia in adults with relatively well-controlled type 1 diabetes.This is the author accepted manuscript. The final version can be found published here: http://care.diabetesjournals.org/content/37/7/1931.abstract

Phenolics from Rhagadiolus stellatus (Asteraceae, Cichorieae)

Rhagadiolus stellatus Gaertn., a Mediterranean member of the Cichorieae tribe of the Asteraceae family used as a food plant, was analyzed for its spectrum of phenolic compounds. Kaempferol 3-O-β-glucoside 1, kaempferol 3-O-β-rutinoside (nicotiflorin) 2, quercetin 3-O-β-glucoside 3, and luteolin 4 were isolated from the n-butanol layer of a methanolic extract of whole plants of Rh. stellatus of Spanish origin by repeated Sephadex LH-20 column chromatography. Structures were determined based on NMR and MS data as well as by comparison with literature data. Additionally, chlorogenic acid 5 and 3,5-dicaffeoylquinic acid 6 were detected by HPLC/DAD and HPLC/MS. Chemosystematic implications of the presented findings are discussed in comparison with other members of the Cichorieae tribe

A prolonged run-in period of standard subcutaneous microdialysis ameliorates quality of interstitial glucose signal in patients after major cardiac surgery

We evaluated a standard subcutaneous microdialysis technique for glucose monitoring in two critically ill patient populations and tested whether a prolonged run-in period improves the quality of the interstitial glucose signal. 20 surgical patients after major cardiac surgery (APACHE II score: 10.1 ± 3.2) and 10 medical patients with severe sepsis (APACHE II score: 31.1 ± 4.3) were included in this investigation. A microdialysis catheter was inserted in the subcutaneous adipose tissue of the abdominal region. Interstitial fluid and arterial blood were sampled in hourly intervals to analyse glucose concentrations. Subcutaneous adipose tissue glucose was prospectively calibrated to reference arterial blood either at hour 1 or at hour 6. Median absolute relative difference of glucose (MARD), calibrated at hour 6 (6.2 (2.6; 12.4) %) versus hour 1 (9.9 (4.2; 17.9) %) after catheter insertion indicated a significant improvement in signal quality in patients after major cardiac surgery (p < 0.001). Prolonged run-in period revealed no significant improvement in patients with severe sepsis, but the number of extreme deviations from the blood plasma values could be reduced. Improved concurrence of glucose readings via a 6-hour run-in period could only be achieved in patients after major cardiac surgery

A new eudesmane derivative from Leontodon tuberosus

Besides the known compounds 2,4,6-trihydroxyacetophenone 4-O-β -D-glucopyranoside and syringaresinol 4&apos;-O-β -D-glucopyranoside, the novel sesquiterpenoid 1,2-dehydro-3-oxocostic acid β -D-glucopyranoside ester was isolated from Leontodon tuberosus L. and its structure established by mass spectrometry and 1D-and 2D-NMR spectroscopy. Additionally, a number of fatty and phenolic acids was identified in the crude methanolic extract by HPLC-DAD and HPLC-MS. The chemosystematic impact of the new sesquiterpenoid is discussed briefly

Clinical Evaluation of Subcutaneous Lactate Measurement in Patients after Major Cardiac Surgery

Minimally invasive techniques to access subcutaneous adipose tissue for glucose monitoring are successfully applied in type1 diabetic and critically ill patients. During critical illness, the addition of a lactate sensor might enhance prognosis and early intervention. Our objective was to evaluate SAT as a site for lactate measurement in critically ill patients. In 40 patients after major cardiac surgery, arterial blood and SAT microdialysis samples were taken in hourly intervals. Lactate concentrations from SAT were prospectively calibrated to arterial blood. Analysis was based on comparison of absolute lactate concentrations (arterial blood vs. SAT) and on a 6-hour lactate trend analysis, to test whether changes of arterial lactate can be described by SAT lactate. Correlation between lactate readings from arterial blood vs. SAT was highly significant (r2 = 0.71, P < .001). Nevertheless, 42% of SAT lactate readings and 35% of the SAT lactate trends were not comparable to arterial blood. When a 6-hour stabilization period after catheter insertion was introduced, 5.5% of SAT readings and 41.6% of the SAT lactate trends remained incomparable to arterial blood. In conclusion, replacement of arterial blood lactate measurements by readings from SAT is associated with a substantial shortcoming in clinical predictability in patients after major cardiac surgery