Thermal response of rats to different types of trauma.
BACKGROUND
Hypothermia is commonly observed in victims of trauma, and it is generally combined with shock caused by either hemorrhagic or nonhemorrhagic mechanisms. This study deals with phenomena related to nonhemorrhagic mechanisms. The objective is to document through experimental evidence the existence of a natural mechanism in rats that compensates for the inadequate tissue perfusion in the presence of shock by reducing body temperature (hypothermia).


METHODS
Different types of trauma are analyzed (i.e., abdominal cavity and bowel exposure) and compared with other groups that suffered, additionally, femur fracture and partial hepatectomy. Further thermal alterations are also studied as consequences of vascular phenomena involving the elevation of intra-abdominal pressure and clamping of arteries and veins, such as the aorta and inferior vena cava. The loss of energy and temperature response of the animals is documented in time through charts with experimental uncertainties.


RESULTS
It is concluded that exposure of the bowels is the main factor involved in the genesis of hypothermia, regardless of the associated trauma. Plastic film is shown to be the most effective way to avoid heat loss in bowel exposure. An optimal intra-abdominal pressure, Popt congruent with 12 mm Hg, is found such that heat flux loss is minimum in pneumoperitoneal procedures.


CONCLUSIONS
Aortic and inferior vena cava clamping induces hypothermia at levels comparable to bowel exposure.
Colman
Daniel
D
Serviço de Cirurgia Geral do Hospital Universitário Cajuru, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil.
Vargas
José V C
JV
Brioschi
Marcos L
ML
Lorusso
Maria I C
MI
da Silva
Alexandre K
AK
D000005:Abdomen / Q000601:surgery; D000704:Analysis of Variance; D000818:Animals; D001833:Body Temperature Regulation; D004195:Disease Models, Animal; D005264:Femoral Fractures / Q000503:physiopathology; D006488:Hemostasis, Surgical / Q000009:adverse effects; D007035:Hypothermia / Q000209:etiology* / Q000503:physiopathology*; D007813:Laparotomy / Q000009:adverse effects; D008297:Male; D011027:Pneumoperitoneum / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar; D012769:Shock / Q000503:physiopathology*; D013514:Surgical Procedures, Operative / Q000009:adverse effects*; D015599:Trauma Severity Indices; D035501:Uncertainty; D014947:Wounds and Injuries / Q000503:physiopathology*