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Biomedical subjects

T E Dudar

Publications and source records attributed to T E Dudar.

3 recordsLinked to original sources

Comparison of the microbial barrier properties of a needleless and a conventional needle-based intravenous access system.

BACKGROUND: Sporadic reports of increased infection rates involving concerning access systems, especially in home-care setting, have raised questions concerning the safety of all needleless systems. Addressing this concern, Baxter Healthcare Corporation and the Centers for Disease Control an d Prevention performed parallel laboratory studies comparing the microbial barrier properties of the Interlink (trademark of Baxter Healthcare Corporation, Deerfield, Ill) needleless system with a conventional intravenous access system. METHODS: Studies of needleless and conventional systems evaluated fluid path contamination introduced through injection site septa, which were intentionally inoculated with high levels of bacteria and subsequently punctured with a without alcohol swabbing disinfection before access. RESULTS: With disinfection, the combined effects of the disinfection technique and the barrier properties of the septa prevented the transfer of organisms into the fluid path in 94% to 96% of needleless test articles and 96% to 100% of conventional test articles. Without disinfection, the barrier properties of the septa alone prevented the transfer of organisms into the fluid path in 20% to 69% of needleless test article and 10% to 28% of conventional test articles. CONCLUSIONS: The data demonstrate the needless system performs as well as the conventional intravenous access system with respect to the risk of microbial contamination and reinforce the need for appropriate septum disinfection before accessing either system.

2-Propanol↗

Differential response of normal and tumor microcirculation to hyperthermia.

RBC velocity and vessel lumen diameter were measured in individual microvessels in normal (mature granulation) and neoplastic (VX2 carcinoma) tissues grown in a transparent rabbit ear chamber. Blood flow rates were determined before, during, and after local hyperthermia treatments at 40-52 degrees for 1 hr. Blood flow in normal tissue increased dramatically with temperature, but stasis occurred at higher temperatures and/or longer durations of heating. In tumors, blood flow rate did not increase as much, and stasis occurred at lower levels of hyperthermia. Both the magnitude and the time of maximum flow appeared to be bimodal functions of temperature. That is, both of these parameters increased with temperature up to a certain critical temperature, and then decreased at higher temperatures. This critical temperature was approximately 45.7 degrees in normal tissue and 43.0 degrees in tumors. Normal tissue required temperatures greater than 47 degrees to bring about vascular stasis in less than 1 hr, while stasis occurred in tumors in the same time frame at temperatures greater than 41 degrees. Normal tissue could increase its maximum flow capacity up to 6 times its preheating value, while neoplastic tissue could only double its maximum flow capacity. This differential flow response in individual microvessels was used to develop a theoretical framework relating various mechanisms of blood flow modifications due to hyperthermia.

Animals↗

Microcirculatory flow changes during tissue growth.

Red blood cell (RBC) velocities, lumen diameters, and volumetric flow rates were determined as functions of position and time in the microvessels of repairing tissue grown in a transparent rabbit ear chamber. By making repeated measurements in the same region, and in many instances, in exactly the same vessel over the entire growth period, we have discerned a distinct microcirculatory flow trend. The flow to a particular region (vessel) increases rapidly after an initial lag time, peaks out, and eventually decays to a steady-state level. This behavior is analogous to the vessel density pattern previously observed in this laboratory, but is delayed in time 1 to 2 weeks. These observations are consistent with mechanical, biochemical, and physiological mechanisms underlying neovascularization, tissue growth, and blood flow regulation, and provide a quantitative understanding of these processes.

Animals↗