Zuzana Pacáková

Discard volume necessary for elimination of heparin flush effect on thromboelastography.

Heparin is commonly used to prevent obstruction of indwelling arterial catheters with blood clots. It is known to affect the outcomes of analysis of coagulation parameters with thromboelastography (TEG); therefore, it has been recommended to neutralize its effect with heparinase. However, heparinase may also neutralize the effect of low molecular weight heparin and endogenous heparinoids present in critically ill patients and thus yields unreliable results. The aim of this study was to evaluate the minimal discard blood volume needed to eliminate the effect of heparin flush on TEG parameters without the use of heparinase. Ten patients with indwelling arterial catheter were included in the study. Coagulation parameters were evaluated with kaolin-activated TEG. Blood samples were obtained after discarding 1, 2, 3, 4, 5 or 10 ml of blood to eliminate the effect of heparin. We investigated the influence of the discard volume on time until the first detectable clot (R), speed of clot development (α angle), maximal amplitude of the measured clot and time to maximal amplitude of the measured clot. We found an increase in coagulation (reflecting the heparin elimination) with the increasing discard volume between 1 and 4 ml. This was obvious from an increase in α angle and maximal amplitude of the measured clot and a decrease in R and time to maximal amplitude of the measured clot (P < 0.001). However, values obtained after discarding 4, 5 and 10 ml of blood did not differ markedly. To obtain valid information about TEG parameters, it is necessary to discard volume of at least 4 ml of blood (i.e., five times the volume of catheter dead space).

Individual human odor fallout as detected by trained canines

We tested the hypothesis that if odor fallout (the release of a humans odor onto an untouched object) in human subjects exists, then holding a hand above an absorbent will produce a detectable scent which will be subsequently matched in a detection test by trained canines. Scents were collected from seven males to sterile cotton absorbent squares. The left hand was used to get the control scent and the right hand served as the target scent. Each experimental subject was sitting; his left hand was laid down on a cotton square for 3 min. The right hand was held 5 cm above another cotton square for 3 min. The scent identification was done by two specially trained police German shepherds. These canines had routinely performed scent identification line-ups as part of criminal investigation procedures. Both canines performed 14 line-ups and correctly matched the collected scents of all test subjects. The results suggest the existence of human odor fallout, whereby a human scent trace is left by humans even if they do not touch an object.