Preliminary study of the effect of acute antemortem haemorrhage on postmortem abdominal impedance in rats.
Studies over many years have revealed a consistent, inverse relationship between extracellular impedance of the rat abdomen and postmortem interval (PMI). Recent studies have shown that this relationship can be improved by correcting measured impedances to their theoretically predicted values at an arbitrarily chosen temperature of 40 degrees C, thus rendering them independent of the tissues' temperature at the time of impedance measurement. The present study, undertaken as a part of an ongoing effort to identify variables which might influence postmortem rate of change in abdominal impedance, was aimed at studying the possible effect of acute antemortem haemorrhage on abdominal impedance. Sudden loss of approximately 30% of the total blood volume, immediately prior to the death was without statistically significant effect on the pattern of postmortem change in abdominal impedance. Thus, in the control and experimental rats, respectively, impedance decreased progressively from 58.7 +/- 1.8 and 68.0 +/- 11.3 omega, 1 h postmortem, to 31.5 +/- 2.2 and 33.7 +/- 4.7 omega at a postmortem interval of 120 h (n = 6 in each group). In both groups, the relationship between impedance and postmortem interval was either linear or curvilinear. These findings are believed to mitigate in favour of continued effort to examine the potential usefulness of abdominal impedance, as an index of postmortem interval, under conditions encountered in routine forensic investigation.
Querido
David
D
Department of Human Biology, Wernher & Beit Building, (South), Faculty of Health Sciences, University of Cape Town Medical School, Cape Town, South Africa. dquerido@curie.uct.ac.za
D000005:Abdomen / Q000502:physiology*; D000818:Animals; D001823:Body Composition / Q000502:physiology; D001831:Body Temperature / Q000502:physiology; D017097:Electric Impedance; D005110:Extracellular Space / Q000502:physiology; D006470:Hemorrhage / Q000503:physiopathology*; D023421:Models, Animal; D008991:Monitoring, Physiologic; D011180:Postmortem Changes; D051381:Rats; D020318:Rats, Long-Evans; D013997:Time Factors