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At least 163 records · Page 9Linked to original sources
PubMed1984

Principles of photometry of the papilla.

To enhance the qualitative information gained by photographing the optic nerve head, we built a silicon photovoltaic detector (photodiode) in the image plane of a fundus camera (Zeiss). It permitted quantitative evaluation of the relative brightness of the illuminated papilla. Following construction of the device and during the early course of more than 260 measurement sessions (on more than 130 subjects), several heretofore unknown sources of error were encountered and subsequently dealt with, resulting in a margin of error for the entire system of between 0.3% and 1.2%. Pallor of the optic nerve head induced by artificial ocular hypertension can be well reproduced by this method.

Humans↗
PubMed1998

[Prothrombin time and thromboplastin time. On-site measurement of the prothrombin time and activated partial thromboplastin time of surgical patients with laser photometry].

UNLABELLED: Turnaround time for analysis of prothrombin time (PT) and activated partial thromboplastin time (APTT) by standard laboratory methods ranges between 40 min and several hours. The delay in obtaining the test results limits their clinical utility for treatment of perioperative coagulation disorders and adequate anti-coagulation therapy. In this study, we compared on-site coagulation testing (OCT) of whole blood, which takes about 3 min, with standard laboratory plasma coagulation tests by our institutional laboratory (LAB) to assess the accuracy of the OCT in a clinical setting (abdominal and postcardiac surgery). METHODS: PT of 62 patients with abdominal surgery was measured intra- and postoperatively using both LAB (KC 40, Thromborel S, Centeon) and OCT (CoaguChek Plus, Boehringer Mannheim) systems. APTT was determined by LAB-(KC 40, Pathromtin, Centeon) and OCT-methods in 53 patients who underwent cardiac surgery requiring cardiopulmonary bypass. RESULTS: Linear regression demonstrated a strong and significant (p = 0.0001) correlation of OCT- and LAB-determinations both for PT (r = 0.92) and APTT (r = 0.91). For PT testing, bias analyses showed an agreement between OCT- and LAB-International Normalized Ratio (INR) (bias = 0.24; relative error = 14.6%) that was considered clinically acceptable, with 95% of the INR-differences lying between -0,26 and +0,74 (mean +/- 2 SD). Although commercial APTT-reagents usually differ in their sensitivity to heparin, we also found an acceptable agreement between OCT- and LAB-APTT values (bias = 6.7 s +/- 22 s; mean +/- 2 SD; relative error = 12%). CONCLUSION: On-site coagulation monitoring provides a rapid, convenient, and accurate assessment of coagulation that can both guide specific anti-coagulation therapy and optimize therapy control of coagulation disorders after cardiac and abdominal operations. As a consequence, OCT offers a valuable tool to reduce the inappropriate use of fresh frozen plasma and to improve cost-effectiveness.

Humans↗
PubMed2001

Comparative study of the determination of peroxomonosulfate, in the presence of other oxidants, by capillary zone electrophoresis, ion chromatography, and photometry.

Several methods for quantitative determination of peroxomonosulfate in detergents, in the presence of other oxidants, have been investigated. The photometric technique applied was based on the well-known starch-iodine reaction. The oxidizing agent was quantified by determining the amount of iodine produced. The influence of other oxidants present was examined. Ion analysis was performed by capillary zone electrophoresis (CZE) and ion chromatography (IC). Because peroxomonosulfate in detergents is always accompanied by sulfate, the main goal was to separate the sulfur species without causing the decomposition of the unstable peroxomonosulfate ion. The sulfur species could be separated within less than 4 min by CZE with a pyromellitic acid electrolyte at pH 3.5 to 5.0. Sulfate and peroxomonosulfate were separated by IC within 11 min by use of a phthalic acid mobile phase at pH 3.0. The peroxomonosulfate content was determined by calibration. The calibration plot was linear from 5 to 50 microg mL(-1) SO5(2-) for IC and from 7.3 to 182.3 microg mL(-1) SO5(2-) (corresponding to 20 to 500 microg mL(-1) triple salt) for CZE.

Chromatography, Ion Exchange↗