Stability In Whole Blood Research Articles

A biocompatible enzyme electrode for continuous in vivo glucose monitoring in whole blood

Electrode fouling and biocompatibility problems remain the greatest obstacles to developing a stable glucose sensor for continuous in vivo monitoring in whole blood. Nafion encapsulation successfully prevents electrode fouling, and substantially inproves the stability and performance of whole blood and plasma glucose sensors in vitro. Results are presented which indicate that Nafion also provides a biocompatible interface with the body, and hence offers the potential for use with implantable sensors. A biocompatible enzyme electrode system is proposed, based on Nafion polymer encapsulation, which has a suitable size and geometry to be tested as an implantable sensor for long-term use. A custom-designed CMOS integrated potentiost was used to evaluate the electrode response in whole blood.

Cholesterol and triglyceride stability in whole blood.

Cholesterol and triglyceride stability in whole blood.

Stability of arterial concentrations during continuous inhalation of C15O2 and 15O2 and the effects on computed values of CBF and CMRO2.

Stability of arterial whole blood and plasma concentrations is a basic requirement in the application of the oxygen-15 (15O2) steady-state inhalation technique for measuring regional cerebral blood flow and oxygen use. The level of stability obtainable in practice is reported in the form of retrospectively analysed blood data from 626 consecutive studies in patients with a range of clinical conditions. Serial arterial whole blood and plasma concentrations were measured during both C15O2 and 15O2 inhalations, and coefficients of variation were calculated. In addition, these concentrations were compared with the corresponding values recorded at the start of each study and maximum variations were calculated. For all four concentrations, mean and median coefficients of variation were around 5 and 4%, respectively. Mean and median maximum variations were around 9 and 7%, respectively. The effects of these variations on the calculations of regional cerebral blood flow, oxygen extraction, and oxygen use were estimated. Mean expected errors were found to be between 4 and 9%, and median expected errors between 3 and 6%. Inherent blood sampling errors were assessed from blood volume studies using 11CO-labeled red cells. These errors were found to be less than 3%.

Stability of catecholamines in whole blood, plasma, and platelets.

Checking catecholamine stability in whole blood, plasma, and platelets, we found that specimens stored at room temperature or frozen for periods ranging from 1.5 h to three weeks show no significant difference in measured catecholamine concentration. The implications of these findings are discussed.